Judith K Brown

Interests

Teaching

Plant virology, Insect vector biology, RNAi / dsRNA technology for insect vector control

Research

Plant virology (DNA viruses), emerging outbreaks / insect-transmitted viruses/fastidious bacterial plant pathogens; molecular epidemiology and phylodynamics of DNA viruses; functional genomics of insect vector-pathogen interactions; microbiome/virome of soils and plants; beneficial viruses; international collaborative research and training

Courses

Scholarly Contributions

Books

• Brown, J. K. (2016). Vector-Plant Pathogen Interactions. St Paul, MN: APS Press.
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  BOOK EditorVector-Plant Pathogen Interactions. 2016. Ed. Brown, J.K. American Phytopathological Society Press, St Paul MN. 496pp
• Brown, J. K., Brown, J. M., & Brown, J. H. (2016). Vector-Mediated Transmission of Plant Pathogens. The American Phytopathological Society. doi:10.1094/9780890545355
• Brown, J. K. (2010). Taxonomy, molecular systematics, and gene flow in the Bemisia tabaci complex and Bemisia relatives. Springer Netherlands. doi:10.1007/978-90-481-2460-2

Chapters

• Parker, T. A., Gallegos, J. A., Beaver, J., Brick, M., Brown, J. K., Cichy, K., Debouck, D. G., Delgado-Salinas, A., Dohle, S., Ernest, E., de Jensen, C. E., Gomez, F., Hellier, B., Karasev, A. V., Kelly, J. D., McClean, P., Miklas, P., Myers, J. R., Osorno, J. M., , Pasche, J. S., et al. (2023). Genetic resources and breeding priorities in phaseolus beans: Vulnerability, resilience, and future challenges. In Plant Breeding Reviews(pp 289-420). Wiley Blackwell.
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  Genetic vulnerability refers to (sometimes catastrophic) actual or potential losses in the production of a crop (in quantity and/or quality), attributable to spatial or temporal reduction in the crop's biodiversity. Conversely, genetic resilience refers to the natural and anthropic capabilities of this biodiversity to mitigate these reductions in crop production. Here, an assessment is provided of genetic vulnerability and resilience of Phaseolus beans, which provide an abundant and sustainable source of protein and micronutrients for populations around the world. We provide an overview of the economic, nutritional, and cultural role of Phaseolus beans and phylogenetic and diversity analyses of the genus, its five domesticated species, and seven domestications, which provide key foundational information for this appraisal. We then assess the uniformity of the crop in the United States and the main drivers of genetic erosion in the centers of origin of the genus in the Americas. Next, the current and emerging breeding constraints are discussed for biotic and abiotic stresses, morphological and phenological traits, and dietary and cooking needs. To address these vulnerabilities, several resources have been developed and, which have been applied to increase the genetic resilience of Phaseolus beans. The resilience resources include genetic resources collections such as the global collection at the Centro Internacional de Agricultura Tropical (CIAT, Colombia), national collections in the United States, Brazil, the European Union, and elsewhere, which include wild and domesticated types across the genus but focus primarily on domesticated species. Resilience resources also include genome-wide reference DNA sequences for three of the five domesticated species, multiple diversity panels and recombinant inbred populations, and large sets of whole-genome diversity data based on single-nucleotide polymorphism (SNP) arrays, genotyping by sequencing, and whole-genome sequencing of germplasm sets. Numerous marker-trait associations and genes affecting agronomic traits have also been characterized in the genus. In turn, these resources have been successfully utilized to make Phaseolus beans more resistant against biotic and abiotic stresses (including those incurred by climate change) and to improve dietary and culinary quality through significant breeding efforts in the United States, at CIAT (mainly Latin America and Africa) and in national programs in Latin America and Eastern Africa. Future challenges remain, however, which include (1) a continued need for ex situ and in situ conservation of diversity, with agroecologically informed germplasm explorations and integration of farmers into conservation and breeding activities; (2) increased pre-breeding efforts involving gene bank curators and bean improvement scientists; (3) expansion of breeding of domesticated species other than common bean, where appropriate based on their potential adaptation to global climate change and consumer preferences; (4) an increased focus on culinary and dietary improvement; and (5) inclusion of microorganisms (both pathogenic and beneficial) in genetic conservation. We conclude that in the short term (~5 years), Phaseolus beans have limited genetic vulnerability. However, over the longer term, vulnerability due to several factors will increase, which can be addressed by a wide range of the resilience resources presented here.
• Parker, T., Gallegos, J., Beaver, J., Brick, M., Brown, J., Cichy, K., Debouck, D., Delgado-Salinas, A., Dohle, S., Ernest, E., de Jensen, C., Gomez, F., Hellier, B., Karasev, A., Kelly, J., McClean, P., Miklas, P., Myers, J., Osorno, J., , Pasche, J., et al. (2023). Genetic Resources and Breeding Priorities in Phaseolus Beans: Vulnerability, Resilience, and Future Challenges. In Plant Breeding Reviews Vol 46(pp 289-420). John Wiley & Sons, Inc. doi:10.1002/9781119874157.ch6
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  Genetic vulnerability refers to (sometimes catastrophic) actual or potential losses in the production of a crop (in quantity and/or quality), attributable to spatial or temporal reduction in the crop’s biodiversity. Conversely, genetic resilience refers to the natural and anthropic capabilities of this biodiversity to mitigate these reductions in crop production. Here, an assessment is provided of genetic vulnerability and resilience of Phaseolus beans, which provide an abundant and sustainable source of protein and micronutrients for populations around the world. We provide an overview of the economic, nutritional, and cultural role of Phaseolus beans and phylogenetic and diversity analyses of the genus, its five domesticated species, and seven domestications, which provide key foundational information for this appraisal. We then assess the uniformity of the crop in the United States and the main drivers of genetic erosion in the centers of origin of the genus in the Americas. Next, the current and emerging breeding constraints are discussed for biotic and abiotic stresses, morphological and phenological traits, and dietary and cooking needs. To address these vulnerabilities, several resources have been developed and, which have been applied to increase the genetic resilience of Phaseolus beans. The resilience resources include genetic resources collections such as the global collection at the Centro Internacional de Agricultura Tropical (CIAT, Colombia), national collections in the United States, Brazil, the European Union, and elsewhere, which include wild and domesticated types across the genus but focus primarily on domesticated species. Resilience resources also include genome-wide reference DNA sequences for three of the five domesticated species, multiple diversity panels and recombinant inbred populations, and large sets of wholegenome diversity data based on single-nucleotide polymorphism (SNP) arrays, genotyping by sequencing, and whole-genome sequencing of germplasm sets. Numerous marker–trait associations and genes affecting agronomic traits have also been characterized in the genus. In turn, these resources have been successfully utilized to make Phaseolus beans more resistant against biotic and abiotic stresses (including those incurred by climate change) and to improve dietary and culinary quality through significant breeding efforts in the United States, at CIAT (mainly Latin America and Africa) and in national programs in Latin America and Eastern Africa. Future challenges remain, however, which include (1) a continued need for ex situ and in situ conservation of diversity, with agroecologically informed germplasm explorations and integration of farmers into conservation and breeding activities; (2) increased pre-breeding efforts involving gene bank curators and bean improvement scientists; (3) expansion of breeding of domesticated species other than common bean, where appropriate based on their potential adaptation to global climate change and consumer preferences; (4) an increased focus on culinary and dietary improvement; and (5) inclusion of microorganisms (both pathogenic and beneficial) in genetic conservation. We conclude that in the short term (~5 years), Phaseolus beans have limited genetic vulnerability. However, over the longer term, vulnerability due to several factors will increase, which can be addressed by a wide range of the resilience resources presented here.
• Brown, J., & Khan, Z. (2022). Breeding cotton for cotton leaf curl disease resistance. In Cotton Breeding and Biotechnology Challenges and Opportunities(pp 171-198). CRC Press. doi:10.1201/9781003096856-11
• Brown, J. K., Cicero, J. M., & Fisher, T. J. (2016). Psyllid-transmitted Candidatus Liberibacter species infecting citrus and solanaceous hosts.. In Vector-Mediated Transmission of Plant Pathogens, ed. Brown, J.K.(pp 399-422). APS Press.
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  Brown, J.K., Cicero, J.M., and Fisher, T.J. 2016. Psyllid-transmitted Candidatus Liberibacter species infecting citrus and solanaceous hosts. Pages 399-422 in: Vector-Mediated Transmission of Plant Pathogens, (ed.) Brown, J.K. American Phytopathological Society Press, St. Paul, MN. 496 pp.
• Cicero, J. M. (2016). Whitefly-mediated transmission of begomoviruses: anatomical, biological, and cellular interactions.. In Vector-Mediated Transmission of Plant Pathogens, ed. Brown, J.K.(pp 211-230). St. Paul, MN: American Phytopathological Society Press.
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  Cicero, J.M., and Brown, J.K. 2016. Bemisia tabaci-mediated transmission of begomoviruses: History and anatomical, biological, and cellular interactions. Pages 211-230 in: Vector-Mediated Transmission of Plant Pathogens, (ed). Brown, J.K. American Phytopathological Society Press, St. Paul, MN. 496 pp.GALLEYS RETURNED FALL 2015
• Langham, M., & Brown, J. K. (2016). Plant Pathogenic Viruses. In Plant Pathology: Concepts and Laboratory Exercises, Third Edition, Editors: Trigiano and Ownley.(p. 576). CRC Press; Taylor & Francis Group, LLC.
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  Langham, M., and Brown, J.K. 2016. Plant Pathogenic Viruses. Chapter 14 in: Plant Pathology: Concepts and Laboratory Exercises, Third Edition, Editors: Trigiano and Ownley. Taylor & Francis Group, LLC. 576 pp. TEXT BOOKContinuing in the tradition of its predecessors, this new edition combines an informal, easy to read style with a thorough introduction to concepts and terminology of plant pathology. After reviewing fundamental concepts, the book discusses groups of plant pathogens and molecular tools for studying them, pathogen interactions, epidemiology and disease control, and special topics in plant pathology. The book details various disease-causing organisms, including viruses, fungi, prokaryotics, nematodes, and various biotic agents. It also examines various plant-pathogen interactions, molecular attack strategies, extracellular enzymes, host defenses, and disruption of plant function.
• Brown, J. (2010). Phylogenetic biology of the Bemisia tabaci sibling species group. In Bemisia: Bionomics and Management of a Global Pest(pp 31-67). Netherlands, Dordrecht: Springer. doi:10.1007/978-90-481-2460-2_2
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  Whiteflies are classified in the family Aleyrodidae (Sternorrhyncha: Hemiptera [suborder Homoptera]) (Mound 1984; Mound and Halsey 1978). The closest relatives to whiteflies are aphids, mealybugs, psyllids, and scales, which all feed using piercing and sucking mouthparts (Martin 1987, 2003; Martin and Mound 2007). © Springer Science+Business Media B.V. 2010.
• Brown, J. K., Brown, J. M., & Brown, J. H. (2010). Phylogenetic Biology of the Bemisia tabaci Sibling Species Group. In Bemisia: Bionomics and Management of a Global Pest.(pp 31-67). Netherlands, Dordrecht: Springer, Dordrecht. doi:10.1007/978-90-481-2460-2_2
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  Whiteflies are classified in the family Aleyrodidae (Sternorrhyncha: Hemiptera [suborder Homoptera]) (Mound 1984; Mound and Halsey 1978). The closest relatives to whiteflies are aphids, mealybugs, psyllids, and scales, which all feed using piercing and sucking mouthparts (Martin 1987, 2003; Martin and Mound 2007).
• Czosnek, H., & Brown, J. (2010). The whitefly genome-White paper: A proposal to sequence multiple genomes of Bemisia tabaci. In Bemisia: Bionomics and Management of a Global Pest(pp 5-29). doi:10.1007/978-90-481-2460-2_18
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  The whitefly, Bemisia tabaci (Gennadius 1889), complex (Brown et al. 1995) can cause extensive damage to crop and ornamental plants. Damage can be biotype specific, including induction of physiological disorders due to feeding alone. More importantly, whitefly transmitted plant viruses cause diseases, which affect fiber, vegetable, and ornamental crops. Most whiteflies in general colonize woody species, while very few utilize herbaceous plants. In this respect, B. tabaci is unique in colonizing herbaceous plant species. © Springer Science+Business Media B.V. 2010.
• Czosnek, H., Brown, J. K., Brown, J. M., & Brown, J. H. (2010). The Whitefly Genome – White Paper: A Proposal to Sequence Multiple Genomes of Bemisia tabaci. In Bemisia, Bionomics and Management of A Global Pest. Bionomics and Management of a Global Pest.(pp 503-532). Springer, Dordrecht. doi:10.1007/978-90-481-2460-2_18
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  The whitefly, Bemisia tabaci (Gennadius 1889), complex (Brown et al. 1995) can cause extensive damage to crop and ornamental plants. Damage can be biotype specific, including induction of physiological disorders due to feeding alone. More importantly, whitefly transmitted plant viruses cause diseases, which affect fiber, vegetable, and ornamental crops. Most whiteflies in general colonize woody species, while very few utilize herbaceous plants. In this respect, B. tabaci is unique in colonizing herbaceous plant species.
• Gill, R. J., Brown, J. K., Brown, J. M., & Brown, J. H. (2010). Systematics of Bemisia and Bemisia Relatives: Can Molecular Techniques Solve the Bemisia tabaci Complex Conundrum – A Taxonomist’s Viewpoint. In Bemisia: Bionomics and Management of a Global Pest.(pp 5-29). Netherlands: Springer, Dordrecht. doi:10.1007/978-90-481-2460-2_1
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  The whitefly, Bemisia tabaci (Gennadius), has a long history as a serious pest of agriculture worldwide. One of the most serious attacks began in 1985–1986 in Florida where very heavy populations infested ornamental and crop plants. By 1990, it had reached the fertile desert croplands of southern Arizona and California, where clouds of whiteflies could be seen flying over the desert valleys.
• Gill, R., & Brown, J. (2010). Systematics of Bemisia and Bemisia Relatives: Can Molecular Techniques Solve the Bemisia tabaci Complex Conundrum-A Taxonomist's Viewpoint. In Bemisia: Bionomics and Management of a Global Pest.(pp 5-29). doi:10.1007/978-90-481-2460-2_1
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  The whitefly, Bemisia tabaci (Gennadius), has a long history as a serious pest of agriculture worldwide. One of the most serious attacks began in 1985-1986 in Florida where very heavy populations infested ornamental and crop plants. By 1990, it had reached the fertile desert croplands of southern Arizona and California, where clouds of whiteflies could be seen flying over the desert valleys. © Springer Science+Business Media B.V. 2010.
• Hadjistylli, M., Brown, J., & Roderick, G. (2010). Tools and recent progress in studying gene flow and population genetics of the Bemisia tabaci sibling species group. In Bemisia: Bionomics and Management of a Global Pest(pp 69-103). doi:10.1007/978-90-481-2460-2_3
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  The use of molecular markers in the Bemisia tabaci complex has been a definitive step in identifying the enormous genetic diversity hidden behind the morphological likeness among its members (see Gill and Brown, Chapter 1), and in determining interrelationships. The presence of biologically-based biotypes in B. tabaci was first realized in the 1950s by Bird (Bird 1957; Bird and Maramorosch 1978), who found that morphologically indistinguishable populations of the whitefly differed substantially in biological and ecological traits, including host range, adaptability to different hosts, and plant virus-transmission efficiencies. Later studies used ecological and biological experiments to examine mating compatibilities as well as differences among distinct populations in phytotoxic induction, insecticide resistance, behavior (Brown et al. 1995b). © Springer Science+Business Media B.V. 2010.
• Hadjistylli, M., Brown, J. K., Roderick, G. K., Brown, J. M., & Brown, J. H. (2009). Tools and Recent Progress in Studying Gene Flow and Population Genetics of the Bemisia tabaci Sibling Species Group. In Bemisia: Bionomics and Management of a Global Pest(pp 69-103). Netherlands: Springer, Dordrecht. doi:10.1007/978-90-481-2460-2_3
  More info

  The use of molecular markers in the Bemisia tabaci complex has been a definitive step in identifying the enormous genetic diversity hidden behind the morphological likeness among its members (see Gill and Brown, Chapter 1), and in determining interrelationships. The presence of biologically-based biotypes in B. tabaci was first realized in the 1950s by Bird (Bird 1957; Bird and Maramorosch 1978), who found that morphologically indistinguishable populations of the whitefly differed substantially in biological and ecological traits, including host range, adaptability to different hosts, and plant virus-transmission efficiencies. Later studies used ecological and biological experiments to examine mating compatibilities as well as differences among distinct populations in phytotoxic induction, insecticide resistance, behavior (Brown et al. 1995b).
• Brown, J., & Brown, J. (2008). Plant Resistance to Viruses: Geminiviruses. In Encyclopedia of Virology(pp 164-170). Oxford: Elsevier. doi:10.1016/B978-012374410-4.00409-X
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  Geminiviruses are a novel group of plant viruses that contain circular, single-stranded DNA of 2.7–5.2 kbp in size. Their unique ‘geminate’ or paired particle sets them apart from other viruses. Geminiviruses are an emergent group of plant viruses characterized by the debilitating diseases they cause, and their ready transmission by one of several phloem-feeding insects. The Geminiviridae contains four genera that are distinguished by host plant type and vector. The largest genus contains the whitefly-transmitted begomoviruses, which are distributed worldwide in the Tropics, and as far north as the Mediterranean Sea and the southern USA. Geminiviruses rely on a host DNA polymerase for replication, and shift cells back into replication phase of the cell cycle to enable their own replication. Geminivirus ORFs (6 and 7) encode multifunctional proteins, including the coat protein that is required for symptom development in some virus–host combinations, and for vector-mediated transmission. Geminiviruses encode a protein enabling cell-to-cell movement, and another that suppresses host defenses, while also serving as a transcriptional activator. Some monopartite begomovirus species associate with a single-stranded DNA (ssDNA) satellite molecule (1.5 kbp) that encodes a silencing suppressor, enabling their debilitated ‘helper virus’ to be pathogenic. Geminiviruses employ recombination and reassortment for diversification and adapt readily to new hosts.
• Brown, J. K., Brown, J. M., & Brown, J. H. (2007). The Bemisia Tabaci Complex: Genetic and Phenotypic Variation and Relevance to TYLCV-Vector Interactions. In Tomato yellow leaf curl virus disease(pp 25-55). New York and Tokyo: Springer, Dordrecht. doi:10.1007/978-1-4020-4769-5_3

Journals/Publications

• Adegbola, R. O., Ilyas, M., Maheepala, D. C., Schuch, U. K., & Brown, J. K. (2025). First Complete Genome Sequence of Palo Verde Broom Emaravirus, Virus-Derived siRNA Signatures, and Phytohormone-Metabolite Profiling of Witches’ Broom-Affected Palo Verde Trees. Viruses, 17(Issue 8). doi:10.3390/v17081122
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  Witches’ broom disease of blue palo verde (Parkinsonia florida) was reported more than sixty years ago. Characteristic symptoms consist of dense clusters of shortened, brittle branches and stunted leaves. The suspect causal agent has been identified as palo verde broom virus (PVBV), genus, Emaravirus, family, Fimoviridae. Here, the first complete PVBV genome sequence was determined, and virus small interfering RNAs (vsiRNAs), primary metabolites, and phytohormone profiles were characterized from infected palo verde leaves, adventitious shoots, flowers, and seeds. Based on pairwise distances, PVBV RNAs 1–4 shared 54–65% nucleotide identity and 19–51% amino acid similarity, respectively, with other emaraviruses, while PVBV RNA 5 shared no sequence homology with any emaravirus. The 21–24-nt virus-derived vsiRNAs, indicative of post-transcriptional gene silencing (PTGS), represented nearly the entire PVBV genome in flowers, leaves, seeds, and adventitious shoots; however, PVBV RNA 3 and RNA 4 were most heavily targeted in all plant parts. Evidence that six major phytohormones were altered in PVBV-infected compared to virus-free trees indicated that emaravirus-infected trees mount classical defense responses to virus infection and/or eriophyid mite infestations. Detection of PVBV RNA genome segments 1–5, accumulation of predominantly 21-nt vsiRNAs, homologous to the PVBV genome and transcripts, and altered levels of phytohormones and metabolites in PVBV-infected trees strongly implicate PVBV as the causal agent of witches’ broom disease.
• Adegbola, R. O., Maheepala, D. C., Schuch, U. K., & Brown, J. K. (2025). Prevalence, host range, and characterization of multiple Palo verde broom emaravirus genomes and eriophyid mites from Parkinsonia spp. in Arizona. Virus Research, 361(Issue). doi:10.1016/j.virusres.2025.199643
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  The palo verde tree is native to the Sonoran Desert and consists of multiple species classified in the genus Parkinsonia, family, Fabaceae. Palo verde broom virus (PVBV), Fimoviridae, Emaravirus, is the suspect causal agent of witches’ broom disease of blue palo verde, P. florida. Here, PVBV was detected in four palo verde species and two hybrids by reverse transcription polymerase chain reaction (RT-PCR) amplification of a 679-base pair (bp) fragment of RNA3, which encodes the nucleocapsid gene (NP). The prevalence of witches’ broom symptoms among the different Parkinsonia species (n = 70), collected from naturally-occurring, nursery- or urban landscape trees was 54 %. Within-species PVBV infection spanned 50–100 % and 81 % across four species and two hybrids combined. The PVBV genome segments RNAs 1–5 were de novo and reference based-assembled from Illumina® RNAseq reads obtained from total RNA isolated from PVBV-positive trees. Pairwise nucleotide identity and amino acid identity for 29 field isolates and GenBank reference PVBV RNA1–5 segments/predicted proteins was 73–100 % and 68–100 %, respectively. Phylogenetic analysis of concatenated RNA1–5 segments resolved four sister clades with no basis in host range among the four palo verde species or hybrids. Five predicted recombinants were identified with breakpoints in either tfhe RNA1 or RNA5 genomic segment. Consistent recovery of PVBV full-length genomes from four Parkinsonia spp. and two hybrids indicated that additional Parkinsonia species and hybrids besides blue palo verde, the only previously reported host, harbored PVBV. Previous studies have linked emaravirus transmission with Eriophyidae mite vectors. Here, the palo verde mite Aculus cercidii Keifer (Eriophyidae) (1965) counts ranged from eight to >1000 per tree. Prolific or minimally-detectable colonization of PVBV-infected trees by A. cercidii, together with consistent detection of PVBV in symptomatic and asymptomatic trees implicate the palo verde mite as the vector of and PVBV as the causal agent of witches’ broom disease.
• Ashraf, M. A., Shahid, I., Brown, J. K., & Yu, N. (2025). An Integrative Computational Approach for Identifying Cotton Host Plant MicroRNAs with Potential to Abate CLCuKoV-Bur Infection. Viruses, 17(Issue 3). doi:10.3390/v17030399
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  Cotton leaf curl Kokhran virus-Burewala (CLCuKoV-Bur) has a circular single-stranded ssDNA genome of 2759 nucleotides in length and belongs to the genus Begomovirus (family, Geminiviridae). CLCuKoV-Bur causes cotton leaf curl disease (CLCuD) and is transmitted by the whitefly Bemisis tabaci cryptic species. Monopartite begomoviruses encode five open reading frames (ORFs). CLCuKoV-Bur replicates through a dsDNA intermediate. Five open reading frames (ORFs) are organized in the small circular, single-stranded (ss)-DNA genome of CLCuKoV-Bur (2759 bases). RNA interference (RNAi) is a naturally occurring process that has revolutionized the targeting of gene regulation in eukaryotic organisms to combat virus infection. The aim of this study was to elucidate the potential binding attractions of cotton-genome-encoded microRNAs (Gossypium hirsutum-microRNAs, ghr-miRNAs) on CLCuKoV-Bur ssDNA-encoded mRNAs using online bioinformatics target prediction tools, RNA22, psRNATarget, RNAhybrid, and TAPIR. Using this suite of robust algorithms, the predicted repertoire of the cotton microRNA-binding landscape was determined for a CLCuKoV-Bur consensus genome sequence. Previously experimentally validated cotton (Gossypium hirsutum L.) miRNAs (n = 80) were selected from a public repository miRNA registry miRBase (v22) and hybridized in silico into the CLCuKoV-Bur genome (AM421522) coding and non-coding sequences. Of the 80 ghr-miRNAs interrogated, 18 ghr-miRNAs were identified by two to four algorithms evaluated. Among them, the ghr-miR399d (accession no. MIMAT0014350), located at coordinate 1747 in the CLCuKoV-Bur genome, was predicted by a consensus or “union” of all four algorithms and represents an optimal target for designing an artificial microRNA (amiRNA) silencing construct for in planta expression. Based on all robust predictions, an in silico ghr-miRNA-regulatory network was developed for CLCuKoV-Bur ORFs using Circos software version 0.6. These results represent the first predictions of ghr-miRNAs with the therapeutic potential for developing CLCuD resistance in upland cotton plants.
• Goenaga, R., Brown, J. K., Rodriguez, J. L., & Serrato, L. M. (2025). Cacao Mild Mosaic Virus Infection of Cacao (Theobroma cacao) Plants in Puerto Rico Does Not Affect Yield. HortScience, 60(Issue 8). doi:10.21273/hortsci18746-25
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  Cacao mild mosaic virus (CaMMV), a member of the Badnavirus genus, has emerged as a prevalent virus in cacao (Theobroma cacao L.) trees in the Caribbean region, Central America, some cacao-producing locations in South America, and Indonesia. Eight cacao genotypes were grown on an Ultisol soil in Corozal, PR, and evaluated for 2 years of production under intensive management to determine their response to CaMMV infection. The results showed significant varietal effects (P < 0.01) on key parameters, including number of pods, dry bean yield, and pod index. The year and the genotype 3 year interaction did not show a significant effect except for pod index. Virus infection among experimental trees averaged 80%, ranging from 73.3% to 100% across genotypes. ‘TARS-9’ was the highest producer with 5544 kg·ha21 per year dry beans, followed by ‘SHRS-7’ (5002 kg·ha21). Despite high CaMMV infection, yield levels were remarkably high, indicating no adverse impact on production. This study marks the first formal report of extraordinary cacao yields reaching 5500 kg·ha21 per year.
• Hernández-Zepeda, C., & Brown, J. K. (2025). Disease Tolerance in ‘Anaheim’ Pepper to PepGMV-D Strain Involves Complex Interactions Between the Movement Protein Putative Promoter Region and Unknown Host Factors. Viruses, 17(Issue 2). doi:10.3390/v17020268
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  Pepper golden mosaic virus (PepGMV) is a bipartite begomovirus of pepper and tomato from North America. In ‘Anaheim’ pepper plants PepGMV-Mo strain (Mo) causes systemic yellow foliar mosaic symptoms, while PepGMV-D strain (D) causes distortion of 1st–6th expanding leaves, and asymptomatic infection of subsequently developing leaves, like other known ‘recovery’ phenotypes. Infections established with DNA-A Mo and D components expressing red-shifted green fluorescent protein in place of coat protein and in situ hybridization, showed PepGMV-Mo localized to phloem and mesophyll cells, while -D was mesophyll restricted. Alignment of PepGMV-Mo and -D DNA-B components revealed three indels upstream of the BC1 gene that encodes the movement protein (MP). To determine if this non-coding region (*BC1) D-strain MP putative promoter contributed to ‘recovery’, plants were inoculated with chimeric DNA-B Mo/D components harboring reciprocally exchanged *BC1, and wild-type DNA-A Mo and D components. Symptoms were reminiscent but not identical to wild-type -Mo or -D infection, respectively, suggesting ‘recovery’ cannot be attributed solely to the *BC1. Both BC1 and D*BC1 were targeted by post-transcriptional gene silencing; however, ‘recovered’ leaves accumulated fewer transcripts and 21–24 nt vsiRNAs. Thus, inefficient in planta movement of PepGMV-D is associated with a non-pepper-adapted ‘defective’ BC1 that facilitates hyper-efficient PTGS, leading to BC1 transcript degradation that in turn limits virus spread, thereby recapitulating disease ‘tolerance’.
• Khan, M. F., Hasan Naqvi, S. A., Iqbal, A., Steichen, S. A., Ali, A., Amir Gulzar, R. M., Brown, J. K., & Din Umar, U. U. (2025). Quantitative analysis of pathogenesis-related protein expression in Gossypium hirsutum L. to elicitor-induced resistance against cotton leaf curl disease and predicted in-silico protein-protein interactions. Physiological and Molecular Plant Pathology, 137(Issue). doi:10.1016/j.pmpp.2025.102611
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  Systemic acquired resistance (SAR) can offer an effective management strategy for plant diseases. Pathogenesis-related (PR) gene expression was investigated in Gossypium hirsutum plants in response to SAR induced by the exogenous application of salicylic acid, jasmonic acid, and benzothiadiazole as elicitors, followed by inoculation with Cotton leaf curl Multan virus (CLCuMuV). Expression of cotton, PR genes encoded on multiple loci were determined by qPCR. Primers were designed based on sequence regions conserved in each group of aligned gene targets in the annotated Gossypium hirsutum reference genome assembly. While designing primers for gene expression analysis, the copy number variation (CNV) was mitigated using bioinformatics and alignment tools to craft primers specific to their target genes. Gene expression of pathogenesis-related proteins such as PR1, PR4, PR5, β 1,3 glucanase, and chitinase was quantified by qPCR. In silico protein interactions were predicted between the five PR and begomoviral proteins using Phyre 2. The results indicated that all the PR genes were expressed on the 2nd date of analysis. The exogenous benzothiadiazole (BTH) application significantly increased all PR gene expression and suppressed the virus infection. The application of BTH after virus inoculation significantly enhanced systemic acquired resistance, which indicates that virus infection initially triggered SAR, and subsequent application of elicitor, i.e., BTH, further facilitated the signal transduction for the expression of PR genes. In silico interactions predicted significant interactions between CLCuMuV coat protein (AV1) gene and Chitinase, PR1, PR5, whereas the replication-associated gene, AC1, interacted with PR1. Results indicate that cotton PR genes suppress the CLCuMuV infection in G. hirsutum plants. The identified PR genes could be exploited to enhance resistance through genetic transformation in cotton plants to control CLCuMuV.
• Kotta-Loizou, I., De Rezende, I. M., Sacchetto, L., & Brown, J. K. (2025). Editorial: Women in fundamental virology. Frontiers in Virology, 5(Issue). doi:10.3389/fviro.2025.1621799
• Naveed, S., Brown, J. K., Mubin, M., Javed, N., & Nawaz-ul-Rehman, M. S. (2025). Potential for Duplexed, In-Tandem gRNA-Mediated Suppression of Two Essential Genes of Tomato Leaf Curl New Delhi Virus in Crop Plants. Pathogens, 14(Issue 7). doi:10.3390/pathogens14070679
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  Tomato leaf curl New Delhi virus (ToLCNDV) is among the most prevalent and widely distributed begomovirus infecting chili pepper (Capsicum annuum) and tomato in the Indian subcontinent. In this study, a guide RNA (gRNA) sequence-CRISPR-Cas9 approach was used to target and cleave two essential coding regions in the begomovirus genome. The gRNAs were designed to target conserved regions of the ToLCNDV replication-associated protein (rep) gene or ORF AC1, and/or the coat protein (cp) gene or AV1 ORF, respectively. Based on an alignment of 346 representative ToLCNDV genome sequences, all predicted single nucleotide polymorphisms off-target sites were identified and eliminated as potential gRNA targets. Based on the remaining genome regions, four candidate gRNAs were designed and used to build gRNA-Cas9 duplexed constructs, e.g., containing two gRNAs cloned in tandem, in different combinations (1–4). Two contained two gRNAs that targeted the coat protein gene (cp; AV1 ORF), while the other two constructs targeted both the cp and replication-associated protein gene (rep; AC1 ORF). These constructs were evaluated for the potential to suppress ToLCNDV infection in Nicotiana benthamiana plants in a transient expression-transfection assay. Among the plants inoculated with the duplexed gRNA construct designed to cleave ToLCNDV-AV1 or AC1-specific nucleotides, the construct designed to target both the cp (293–993 nt) and rep (1561–2324) showed the greatest reduction in virus accumulation, based on real-time quantitative PCR amplification, and attenuated disease symptoms, compared to plants inoculated with the DNA-A component alone or mock-inoculated, e.g., with buffer. The results demonstrate the potential for gRNA-mediated suppression of ToLCNDV infection in plants by targeting at least two viral coding regions, underscoring the great potential of CRISPR-Cas-mediated abatement of begomovirus infection in numerous crop species.
• Ponvert, N., Byrne, F., Rivera, M. J., Rohula, T., Olkowski, S., De Silva Weligodage, H., McRoberts, N., & Brown, J. K. (2025). Spatial and temporal detection of ‘Candidatus Liberibacter asiaticus’ in Diaphorina citri through optimized scouting, sampling, DNA isolation, and qPCR amplification in California citrus groves. PLoS ONE, 20(Issue 5). doi:10.1371/journal.pone.0323908
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  Huanglongbing (citrus greening disease) is caused by the bacterium ‘Candidatus Liberibacter asiaticus’ (CLas) (Alphaproteobacteria) and is one of the most destructive bacterial-vector diseases affecting the citrus industry. The bacterium is transmitted by the Asian citrus psyllid (ACP; Diaphorina citri). Early detection in citrus trees is challenging due to uneven distribution of CLas throughout the tree and a long pre-symptomatic phase of the disease. Due to these limitations, ACP sampling has been suggested as a more reliable early detection strategy. The objective of this study was to develop and optimize approaches for detecting CLas in ACP adults and nymphs collected in citrus groves in California using real-time quantitative PCR (qPCR) and droplet digital PCR (ddPCR). The goal was to establish the optimal number of ACP adults and nymphal instar life stages (stages 1–2, 3, or 4–5) that yielded the most reliable detection of CLas (Cq values ≤ 38). Results indicated that CLas detection correlated with psyllid developmental stage, with the 4th–5th instar nymphs (sample size of five to ten per tube) or adult ACP (sample size of three to ten per tube) providing the most consistent qPCR detection. While CLas detection rates increased with adult ACP age, nymphs were preferred for field sampling as adult ACP might have dispersed from non-infected trees, potentially misrepresenting the grove’s CLas status. Detection by droplet digital PCR confirmed the presence and genome copies of CLas in a subset of ACP across life stages. In field populations, detection rates in nymphs were consistent or stable throughout the year, whereas CLas detection in adults exhibited seasonal variation, with CLas detection and genome load peaking in January. These targeted ACP sampling strategies and optimized laboratory processing methods will facilitate CLas detection in psyllids for streamlining citrus greening disease management.
• Saberi, E., Qureshi, J. A., & Brown, J. K. (2025). Time-Course Gene Expression of ‘Candidatus Liberibacter solanacearum’, Prophage, and Wolbachia Genes in Bactericera cockerelli from Ingestion to in Planta Transmission. Microorganisms, 13(Issue 9). doi:10.3390/microorganisms13092120
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  Psyllids are vectors of fastidious plant pathogenic ‘Candidatus Liberibacter’ species that infect both the psyllid vector and plant host. Understanding the molecular and cellular basis of ‘Ca. Liberibacter’ interactions with the psyllid host will aid in identification of effectors involved in invasion and multiplication and facilitate transmission to the host plant. The differential expression of previously identified genes/loci with predicted involvement in tomato host–plant– ‘Ca. L. solanacearum’–prophage–Wolbachia endosymbiont dynamics was quantified by RT-qPCR amplification. Fifteen ‘Ca. Liberibacter solanacearum genes and/or prophage loci and four predicted Wolbachia spp. loci were analyzed in potato psyllids in a 14-day time-course study, post-48-h acquisition-access period by potato psyllids on ‘Ca. L. solanacearum’-infected tomato plants. The ‘Ca. L. solanacearum’-infected tomato host plants were used as an infected host ‘calibrator’ species lacking involvement of psyllid effectors. ‘Ca. L. solanacearum’ genes with predicted functions in adhesion, motility, transport, and virulence that are associated with the prophage lysogenic lifestyle were differentially expressed. In contrast, the prophage-loci expression was synchronous with early or late phase of psyllid-‘Ca. L. solanacearum’ infection, respectively. The observations are consistent with the previously in silico-predicted ‘Ca. L. solanacearum’ gene and prophage/Wolbachia loci functions and time-course global expression patterns. Knockdown of ‘Ca. L. solanacearum’ genes involved in invasion, biofilm formation, and colonization would be expected to impair the vertical and horizontal transmission of ‘Ca. L. solanacearum’ to psyllid offspring and host plants, respectively.
• Adegbola, R., Keith, C., Gutierrez, O., Goenaga, R., & Brown, J. (2024). Complete genome characterization of cacao leafroll virus, a newly described cacao-infecting polerovirus. Archives of Virology, 169(4), 83. doi:10.1007/s00705-024-06013-7
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  The complete genome sequence of cacao leafroll virus (CaLRV; family Solemoviridae, genus Polerovirus) was determined by high-throughput sequencing of total RNA isolated from symptomatic cacao Theobroma cacao L. plants (n = 4). The CaLRV genome sequences ranged from 5,976 to 5,997 nucleotides (nt) in length and contained seven open reading frames (ORFs). Nucleotide and amino acid (aa) sequence comparisons showed that, among selected well-characterized poleroviruses, the CaLRV genome shared the highest nt sequence identity of 62% with that of potato leafroll virus (PLRV, NC_076505). A comparison of the predicted aa sequence of the CaLRV coat protein indicated that cotton leafroll dwarf virus (CLRDV, NC_014545) and melon aphid-borne yellows virus (MABYV, NC_010809) were the closest relatives, sharing 57% aa sequence identity. Bayesian phylogenetic analysis based on complete genome sequences showed that CaLRV grouped with well-characterized poleroviruses that cause diseases of cereal and vegetable crops. During the course of publishing this work, the nearly complete genome sequence of a member of the same polerovirus species, referred to as “cacao polerovirus” (OR605721), with which CaLRV shares 99% nt sequence identity, was reported.
• Adegbola, R., Ponvert, N., & Brown, J. (2024). Genetic Variability Among U.S.-Sentinel Cotton Plot Cotton Leafroll Dwarf Virus and Globally Available Reference Isolates Based on ORF0 Diversity. Plant Disease, 108(4), 1-13. doi:10.1094/PDIS-02-23-0243-RE
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  The aphid-transmitted polerovirus, cotton leafroll dwarf virus (CLRDV), first characterized from symptomatic cotton plants in South America, has been identified in commercial cotton plantings in the United States. Here, the CLRDV intraspecific diversity was investigated by comparative sequence analysis of the most divergent CLRDV coding region, ORF0/P0. Bayesian analysis of ORF0 sequences for U.S. and reference populations resolved three well-supported sister clades comprising one U.S. and two South American lineages. Principal component analysis (PCA) identified seven statistically supported intraspecific populations. The Bayesian phylogeny and PCA dendrogram-inferred relationships were congruent. Population analysis of ORF0 sequences indicated most lineages have evolved under negative selection, albeit certain sites/isolates evolved under positive selection. Both U.S. and South American isolates exhibited extensive ORF0 diversity. At least two U.S. invasion foci were associated with their founder populations in Alabama-Georgia and eastern Texas. The Alabama-Georgia founder is implicated as the source of recent widespread expansion and establishment of secondary disease foci throughout the southeastern-central United States. Based on the geographically restricted distribution, spread of another extant Texas population appeared impeded by a population bottleneck. Extant CLRDV isolates represent several putative introductions potentially associated with catastrophic weather events dispersing viruliferous cotton aphids of unknown origin(s).
• Ameyaw, G., Kouakou, K., Iqbal, M., Wolf, V., Keith, C., Bi, B., Livingstone, D., Domfeh, O., Gyamera, E., Marelli, J., Brown, J., Belé, L., & Kouamé, C. (2024). Molecular Surveillance, Prevalence, and Distribution of Cacao Infecting Badnavirus Species in Côte d’Ivoire and Ghana. Viruses, 16(5). doi:10.3390/v16050735
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  The cacao swollen shoot disease (CSSD) caused by a complex of badnavirus species presents a major challenge for cacao production in West Africa, especially Ghana and Côte d’Ivoire. In this study, CSSD species detection efficiency, diversity, and geographic distribution patterns in cacao plantations in Ghana and Côte d’Ivoire were investigated through field surveillance, PCR detection assays, sequencing of positive amplicons, and phylogeographic clustering. Cumulatively, the detection efficiency of the tested CSSD primer sets that were targeting the movement protein domain of the virus ranged from 0.15% (CSSD-3 primer) to 66.91% (CSSD-1 primer) on all the symptomatic cacao leaf samples assessed. The identified CSSD species differed phylogenetically and overlapped in distribution, with the cacao swollen shoot Togo B virus (CSSTBV) (n = 588 sequences) being the most prevalent and widely distributed compared to the other CSSD species that were encountered in both countries. Geographically, the cacao swollen shoot CE virus (CSSCEV) species (n = 124 sequences) that was identified was largely restricted to the bordering regions of Ghana and Côte d’Ivoire. These results provide updated knowledge of the geographic distribution of the key CSSD species and their diagnostic efficiency and, thus, provide guidance in identifying locations for structured testing of cacao germplasm and optimal diagnostics for the predominant CSSD species in Ghana and Côte d’Ivoire.
• Ashraf, M., Brown, J., Iqbal, M., & Yu, N. (2024). Genome-Wide Identification of Cotton MicroRNAs Predicted for Targeting Cotton Leaf Curl Kokhran Virus-Lucknow. Microbiology Research, 15, 1-19. doi:10.3390/microbiolres15010001
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  Cotton leaf curl Kokhran virus (CLCuKoV) (genus, Begomovirus; family, Geminiviridae) is one of several plant virus pathogens of cotton (Gossypium hirsutum L.) that cause cotton leaf curl disease in Pakistan. Begomoviruses are transmitted by the whitefly Bemisia tabaci cryptic species group and cause economic losses in cotton and other crops worldwide. The CLCuKoV strain, referred to as CLCuKoV-Bur, emerged in the vicinity of Burewala, Pakistan, and was the primary causal virus associated with the second CLCuD epidemic in Pakistan. The monopartite ssDNA genome of (2.7 Kb) contains six open reading frames that encode four predicted proteins. RNA interference (RNAi)-mediated antiviral immunity is a sequence-specific biological process in plants and animals that has evolved to combat virus infection. The objective of this study was to design cotton locus-derived microRNA (ghr-miRNA) molecules to target strains of CLCuKoV, with CLCuKoV-Lu, as a typical CLCuD-begomovirus genome, predicted by four algorithms, miRanda, RNA22, psRNATarget, and RNA hybrid. Mature ghr-miRNA sequences (n = 80) from upland cotton (2n = 4x = 52) were selected from miRBase and aligned with available CLCuKoV-Lu genome sequences. Among the 80 cotton locus-derived ghr-miRNAs analyzed, ghr-miR2950 was identified as the most optimal, effective ghr-miRNA for targeting the CLCuKoV-Lu genome (nucleotide 82 onward), respectively, based on stringent criteria. The miRNA targeting relies on the base pairing of miRNA–mRNA targets. Conservation and potential base pairing of binding sites with the ghr-miR2950 were validated by multiple sequence alignment with all available CLCuKoV sequences. A regulatory interaction network was constructed to evaluate potential miRNA–mRNA interactions with the predicted targets. The efficacy of miRNA targeting of CLCuKoV was evaluated in silico by RNAi-mediated mRNA cleavage. This predicted targets for the development of CLCuD-resistant cotton plants.
• Ibrahim, Y., Al-Saleh, M., Widyawan, A., El Komy, M., Al Dhafer, H., & Brown, J. (2024). Identification and Distribution of the ‘Candidatus Liberibacter asiaticus’-Asian Citrus Psyllid Pathosystem in Saudi Arabia. Plant Disease, 108(4), 1083-1092. doi:10.1094/PDIS-07-23-1460-RE
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  Citrus greening disease was first reported in Saudi Arabia during the 1970s when characteristic foliar and fruit symptoms were observed in commercial citrus groves. However, ‘Candidatus Liberibacter asiaticus’ (CLas) was not detected in symptomatic trees until 1981 to 1984 when CLas-like cells were observed by transmission electron microscopy in leaves collected from symptomatic citrus groves in southwestern Saudi Arabia. Despite the anticipated establishment of the CLas-Asian citrus psyllid (ACP) (Diaphorina citri Kuwayama) pathosystem, CLas presence has not been verified in suspect trees nor have ACP infestations been documented. Given the recent expansion of citrus production in Saudi Arabia, a systematic country-wide survey was carried out to determine the potential CLas distribution in the 13 citrus-growing regions of the country. Citrus trees were surveyed for the presence of CLas-psyllid vector(s) and characteristic disease symptoms in commercial and urban citrus trees. Adult psyllids collected from infested citrus trees were identified as ACP based on morphological characteristics. Real-time quantitative PCR amplification (qPCR) of the CLas b-subunit of the ribonucleotide reductase (RNR) gene from citrus leaf and fruit samples and/or ACP adults revealed that trees were positive for CLas detection in 10 of the 13 survey regions; however, CLas was undetectable in ACP adults. Phylogenetic and single nucleotide polymorphism (SNP) analyses of a PCR-amplified, cloned fragment of the CLas 16S rRNA gene (~1.1 kbp) indicated Saudi Arabian isolates were most closely related to Florida, U.S.A., isolates. Analysis of climate variables indicated that the distribution of the ACP-CLas pathosystem observed in Saudi Arabia was consistent with published predictions of terrains most likely to support establishment.
• Johnson, L., Umaharan, P., Roye, M. E., Brown, J. K., & Tennant, P. (2024). First report of sweepoviruses infecting Ipomeas batatas L. cultivars and landraces in Trinidad. Plant Disease. doi:10.1094/pdis-01-24-0031-pdn
• Marchant, W., Brown, J., Gautam, S., Ghosh, S., Simmons, A., & Srinivasan, R. (2024). Non-Feeding Transmission Modes of the Tomato Yellow Leaf Curl Virus by the Whitefly Bemisia tabaci Do Not Contribute to Reoccurring Leaf Curl Outbreaks in Tomato. Insects, 15(10), 760. doi:10.3390/insects15100760
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  Tomato yellow leaf curl virus (TYLCV) causes significant yield loss in tomato production in the southeastern United States and elsewhere. TYLCV is transmitted by the whitefly Bemisia tabaci cryptic species in a persistent, circulative, and non-propagative manner. Unexpectedly, transovarial and sexual transmission of TYLCV has been reported for one strain from Israel. In this study, the potential contribution of the B. tabaci B cryptic species transovarial and sexual transmission of TYLCV (Israel strain, Georgia variant, Georgia, USA) to reoccurring outbreaks was investigated by conducting whitefly-TYLCV transmission assays and virus DNA detection using end point PCR, DNA quantitation via real-time PCR, and virion detection by immunocapture PCR. TYLCV DNA was detectable in four, two, and two percent of first-generation fourth-instar nymphs, first-generation adults, and second-generation adults, respectively, following transovarial acquisition. Post-mating between viruliferous counterparts, the virus’s DNA was detected in four percent of males and undetectable in females. The accumulation of TYLCV DNA in whiteflies from the transovarial and/or sexual experiments was substantially lower (100 to 1000-fold) compared with whitefly adults allowed a 48-hr acquisition-access period on plants infected with TYLCV. Despite the detection of TYLCV DNA in whiteflies from the transovarial and/or mating experiments, the virions were undetectable by immunocapture PCR—a technique specifically designed to detect virions. Furthermore, tomato test plants exposed to whitefly adults that presumably acquired TYLCV transovarially or through mating remained free of detectable TYLCV DNA. Collectively, the extremely low levels of TYLCV DNA and complete absence of virions detected in whiteflies and the inability of the B. tabaci cryptic species B to transmit TYLCV to test tomato plants following transovarial and mating acquisition indicate that neither transovarial nor sexual transmission of TYLCV are probable or epidemiologically relevant for TYLCV persistence in this pathosystem.
• Saberi, E., , ., Mondal, M., Paredes-Montero, J., Nawaz, K., Brown, J., & Qureshi, J. (2024). Optimal dsRNA Concentration for RNA Interference in Asian Citrus Psyllid. Insects, 15(1), 58. doi:10.3390/insects15010058
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  The Asian citrus psyllid (ACP) is a citrus pest and insect vector of “Candidatus Liberibacter asiaticus”, the causal agent of citrus greening disease. Double-stranded RNA (dsRNA) biopesticides that trigger RNA interference (RNAi) offer an alternative to traditional insecticides. Standardized laboratory screening of dsRNA requires establishing the minimal effective concentration(s) that result in effective RNAi “penetrance” and trigger RNAi, resulting in one or more measurable phenotypes, herein, significant gene knockdown and the potential for mortality. In this study, knockdown was evaluated for a range of dsRNA concentrations of three ACP candidate genes, clathrin heavy chain (CHC), vacuolar ATPase subunit A (vATPase-A), and sucrose non-fermenting protein 7 (Snf7). Gene knockdown was quantified for ACP teneral adults and 3rd instar nymphs allowed a 48 h ingestion-access period (IAP) on 10, 50,100, 200, and 500 ng/µL dsRNA dissolved in 20% sucrose followed by a 5-day post-IAP on orange jasmine shoots. Significant gene knockdown (p < 0.05) in ACP third instar nymphs and adults ranged from 12–34% and 18–39%, 5 days post-IAP on dsRNA at 10–500 and 100–500 ng/µL, respectively. The threshold concentration beyond which no significant gene knockdown and adult mortality was observed post-48 h IAP and 10-day IAP, respectively, was determined as 200 ng/µL, a concentration indicative of optimal RNAi penetrance.
• Saberi, E., Qureshi, J., & Brown, J. (2024). Differential expression of “Candidatus Liberibacter solanacearum” genes and prophage loci in different life stages of potato psyllid. Scientific Reports, 14(1), 16248. doi:10.1038/s41598-024-65156-4
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  Psyllid species, including the potato psyllid (PoP) Bactericera cockerelli (Sulc) (Triozidae) serve as host and vector of “Candidatus Liberibacter spp.” (“Ca. Liberibacter”), which also infects diverse plant hosts, including citrus and tomato. Psyllid transmission of “Ca. Liberibacter” is circulative and propagative. The time of “Ca. Liberibacter” acquisition and therefore vector life stage most competent for bacterial transmission varies by pathosystems. Here, the potato psyllid-“Ca. Liberibacter solanacearum” (CLso) pathosystem was investigated to dissect CLso-prophage interactions in the tomato plant and PoP-psyllid host by real-time quantitative reverse transcriptase amplification of CLso genes/loci with predicted involvement in host infection and psyllid-CLso transmission. Genes/loci analyzed were associated with (1) CLso-adhesion, -invasion, -pathogenicity, and -motility, (2) prophage-adhesion and pathogenicity, and (3) CLso-lysogenic cycle. Relative gene expression was quantified by qRT-PCR amplification from total RNA isolated from CLso-infected 1st–2nd and 4th–5th nymphs and teneral adults and CLso-infected tomato plants in which CLso infection is thought to occur without SC1-SC2 replication. Gene/loci expression was host-dependent and varied with the psyllid developmental stage. Loci previously associated with repressor-anti-repressor regulation in the “Ca Liberibacter asiaticus”-prophage pathosystem, which maintains the lysogenic cycle in Asian citrus psyllid Diaphorina citri, were expressed in CLso-infected psyllids but not in CLso-infected tomato plants.
• Thakre, N., Carver, M., Paredes-Montero, J., Mondal, M., Hu, J., Saberi, E., Ponvert, N., Qureshi, J., & Brown, J. (2024). UV-LASER adjuvant–surfactant-facilitated delivery of mobile dsRNA to tomato plant vasculature and evidence of biological activity by gene knockdown in the potato psyllid. Pest Management Science, 80(4). doi:10.1002/ps.7952
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  BACKGROUND: Double-stranded RNA (dsRNA) biopesticides are of interest for the abatement of insect vectors of pathogenic bacteria such as ‘Candidatus Liberibacter’, which infects both its psyllid and plant hosts. Silencing of genes essential for psyllids, or for Liberibacter, is anticipated to lead to mortality or impeded bacterial multiplication. Foliar delivery is preferred for biopesticide application; however, the cuticle impedes dsRNA penetration into the vasculature. Here, conditions were established for wounding tomato leaves using ultraviolet light amplification by stimulated emissions of radiation (UV-LASER) to promote dsRNA penetration into leaves and vasculature. RESULTS: UV-LASER treatment with application of select adjuvants/surfactants resulted in vascular delivery of 100-, 300- and 600-bp dsRNAs that, in general, were correlated with size. The 100-bp dsRNA required no pretreatment, whereas 300- and 600-bp dsRNAs entered the vasculature after UV-LASER treatment only and UV-LASER adjuvant/surfactant treatment, respectively. Of six adjuvant/surfactants evaluated, plant-derived oil combined with an anionic organosilicon compound performed most optimally. Localization of dsRNAs in the tomato vasculature was documented using fluorometry and fluorescence confocal microscopy. The biological activity of in planta-delivered dsRNA (200–250 bp) was determined by feeding third-instar psyllids on tomato leaves post UV-LASER adjuvant/surfactant treatment, with or without psyllid cdc42- and gelsolin dsRNAs. Gene knockdown was quantified by quantitative, real-time polymerase chain reaction with reverse transcription (RT–qPCR) amplification. At 10 days post the ingestion-access period, knockdown of cdc42 and gelsolin expression was 61% and 56%, respectively, indicating that the dsRNAs delivered to the tomato vasculature were mobile and biologically active. CONCLUSION: Results indicated that UV-LASER adjuvant/surfactant treatments facilitated the delivery of mobile, biologically active dsRNA molecules to the plant vasculature. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
• Thakre, N., Carver, M., Paredes‐Montero, J. R., Mondal, M., Hu, J., Saberi, E., Ponvert, N., Qureshi, J. A., & Brown, J. K. (2024). UV‐LASER adjuvant–surfactant‐facilitated delivery of mobile dsRNA to tomato plant vasculature and evidence of biological activity by gene knockdown in the potato psyllid. Pest Management Science, 80(4), 2141-2153. doi:10.1002/ps.7952
• Arad, N., Paredes-Montero, J. R., Mondal, M. H., Ponvert, N., & Brown, J. K. (2023). RNA interference-mediated knockdown of genes involved in sugar transport and metabolism disrupts psyllid Bactericera cockerelli (Order: Hemiptera) gut physiology and results in high mortality. Frontiers in Insect Science, 3(Issue). doi:10.3389/finsc.2023.1283334
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  Introduction: The causal agent of zebra chip of potato and vein-greening diseases of tomato is "Candidatus Liberibacter solanacearum" (CLso), a fastidious bacterium transmitted by the potato psyllid. In the absence of disease-resistant cultivars, disease management has relied on minimizing vector population size to reduce CLso transmission, which requires frequent insecticide applications. There is growing interest in the use of RNA interference (RNAi) technology to supplant traditional insecticides with biopesticides. This requires knowledge of genes essential for insect livelihood whose knockdown leads to significant mortality or other phenotypes. Such candidate genes can be evaluated by reverse genetics approaches to further corroborate predicted gene function. Methods: Here, five potato psyllid genes involved in sugar homeostasis in the potato psyllid gut, α-glucosidase1 (AGLU1), aquaporin2 (AQP2), facilitated trehalose transporter1 (TRET1), Trehalase1 (TRE1), and Trehalase2 (TRE2), were investigated as candidates for effective gene silencing. Potato psyllid dsRNAs were designed to optimize knockdown of gene targets. Third instar PoP nymphs were given a 48-hr ingestion-access period (IAP) on individual or groups of dsRNA in 20% sucrose. Mortality was recorded 0, 3, 5, 7, and 9 days post-IAP. Gene knockdown was analyzed 9 days post-IAP by quantitative real-time reverse-transcriptase polymerase chain reaction amplification. Results: The individual or stacked dsRNA combinations resulted in 20-60% and 20-40% knockdown, respectively, while subsequent psyllid mortality ranged from 20-40% to >60% for single and stacked dsRNA combinations, respectively. Reverse genetics analysis showed that simultaneous knockdown of the five selected candidate genes with predicted functions in pathways involved in sugar-homeostasis, metabolism, and -transport yielded the highest mortality, when compared with single or combinations of targets. Discussion: Results confirmed the functions afforded by psyllid gut genes responsible for osmotic homeostasis and sugar metabolism/transport are essential for livelihood, identifying them as potentially lucrative RNAi biopesticide targets and highlighted the translational relevance of targeting multiple nodes in a physiological pathway simultaneously.
• Ashraf, M. A., Murtaza, N., Brown, J. K., & Yu, N. (2023). In Silico Apple Genome-Encoded MicroRNA Target Binding Sites Targeting Apple Chlorotic Leaf Spot Virus. Horticulturae, 9(7), 808. doi:10.3390/horticulturae9070808
• Ashraf, M., Ali, B., Brown, J., Shahid, I., & Yu, N. (2023). In Silico Identification of Cassava Genome-Encoded MicroRNAs with Predicted Potential for Targeting the ICMV-Kerala Begomoviral Pathogen of Cassava. Viruses, 15(2). doi:10.3390/v15020486
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  Cassava mosaic disease (CMD) is caused by several divergent species belonging to the genus Begomovirus (Geminiviridae) transmitted by the whitefly Bemisia tabaci cryptic species group. In India and other parts of Asia, the Indian cassava mosaic virus-Kerala (ICMV-Ker) is an emergent begomovirus of cassava causing damage that results in reduced yield loss and tuber quality. Double-stranded RNA-mediated interference (RNAi) is an evolutionary conserved mechanism in eukaryotes and highly effective, innate defense system to inhibit plant viral replication and/or translation. The objective of this study was to identify and characterize cassava genome-encoded microRNAs (mes-miRNA) that are predicted to target ICMV-Ker ssDNA-encoded mRNAs, based on four in silico algorithms: miRanda, RNA22, Tapirhybrid, and psRNA. The goal is to deploy the predicted miRNAs to trigger RNAi and develop cassava plants with resistance to ICMV-Ker. Experimentally validated mature cassava miRNA sequences (n = 175) were downloaded from the miRBase biological database and aligned with the ICMV-Ker genome. The miRNAs were evaluated for base-pairing with the cassava miRNA seed regions and to complementary binding sites within target viral mRNAs. Among the 175 locus-derived mes-miRNAs evaluated, one cassava miRNA homolog, mes-miR1446a, was identified to have a predicted miRNA target binding site, at position 2053 of the ICMV-Ker genome. To predict whether the cassava miRNA might bind predicted ICMV-Ker mRNA target(s) that could disrupt viral infection of cassava plants, a cassava locus-derived miRNA–mRNA regulatory network was constructed using Circos software. The in silico-predicted cassava locus-derived mes-miRNA-mRNA network corroborated interactions between cassava mature miRNAs and the ICMV-Ker genome that warrant in vivo analysis, which could lead to the development of ICMV-Ker resistant cassava plants.
• Ashraf, M., Murtaza, N., Brown, J., & Yu, N. (2023). In Silico Apple Genome-Encoded MicroRNA Target Binding Sites Targeting Apple Chlorotic Leaf Spot Virus. Horticulturae, 9(7). doi:10.3390/horticulturae9070808
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  Apple chlorotic leaf spot virus (ACLSV) (genus, Trichovirus; family, Betaflexiviridae) is a widespread, deleterious, and the most damaging pathogen of pome and fruit trees including domesticated apple (Malus × domestica Borkh.), to which it is transmitted by grafting and pruning. The positive-sense, single-stranded RNA virus is 600–700 nm long and has a genome of 74.7–7.56 kbp in size, minus the poly-A tail and 3′- and 5′-untranslated regions. The genome has three overlapping open reading frames (ORFs) that encode a replication-associated protein (Rep), movement protein (MP), and coat protein (CP). RNA interference (RNAi)-mediated antiviral defense in eukaryotes has evolved to control infections in plant viruses. The objective of this study was to analyze locus-derived microRNAs (mdm-miRNAs) in the apple genome with potential for targeting ACLSV +ssRNA-encoded mRNAs, using a predictive approach that involves four algorithms. The goal is to mobilize the in silico-predicted endogenous mdm-miRNAs and trigger the RNAi pathway experimentally in apple trees to evaluate antiviral resistance to ACLSV. Experimentally validated apple (2n = 2X = 34) mdm-miRNAs (n = 322) were obtained from the miRBase database and aligned to the ACLSV genome (KU870525). Of the 322 targeting mature locus-derived mdm-miRNAs analyzed, nine apple mdm-miRNA homologs (mdm-miR395k, mdm-miR5225c, and mdm-miR7121 (a, b, c, d, e, f, g, h) were predicted by all “four algorithms”, whereas fifty-eight mdm-miRNAs were identified as consensus binding sites by the combined results of two algorithms. The miRanda, RNA22, and TAPIR algorithms predicted binding of mdm-miR395k at nucleotide position 4691 and identified it as the most effective interacting mdm-miRNA targeting the virus ORF1 sequence. An integrated Circos plot was generated to validate the accuracy of target prediction and determine if apple mdm-miRNAs could bind to the predicted ACLSV mRNA target(s). A genome-wide in silico-predicted miRNA-mediated target gene regulatory network was implicated to validate interactions necessary to warrant in vivo analysis. The availability of validated locus-derived microRNAs (mdm-miRNAs) with predicted potential to target ACLSV in infected apple trees represents the first step toward development of ACLSV-resistant apple trees.
• Ashraf, S., Ahmad, A., Khan, S., Jamil, A., Sadia, B., & Brown, J. (2023). LbCas12a mediated suppression of Cotton leaf curl Multan virus. Frontiers in Plant Science, 14. doi:10.3389/fpls.2023.1233295
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  Begomoviruses are contagious and severely affect commercially important fiber and food crops. Cotton leaf curl Multan virus (CLCuMuV) is one of the most dominant specie of Begomovirus and a major constraint on cotton yield in Pakistan. Currently, the field of plant genome editing is being revolutionized by the CRISPR/Cas system applications such as base editing, prime editing and CRISPR based gene drives. CRISPR/Cas9 system has successfully been used against biotic and abiotic plant stresses with proof-of-concept studies in both model and crop plants. CRISPR/Cas12 and CRISPR/Cas13 have recently been applied in plant sciences for basic and applied research. In this study, we used a novel approach, multiplexed crRNA-based Cas12a toolbox to target the different ORFs of the CLCuMuV genome at multiple sites simultaneously. This method successfully eliminated the symptoms of CLCuMuV in Nicotiana benthamiana and Nicotiana tabacum. Three individual crRNAs were designed from the CLCuMuV genome, targeting the specific sites of four different ORFs (C1, V1 and overlapping region of C2 and C3). The Cas12a-based construct Cas12a-MV was designed through Golden Gate three-way cloning for precise editing of CLCuMuV genome. Cas12a-MV construct was confirmed through whole genome sequencing using the primers Ubi-intron-F1 and M13-R1. Transient assays were performed in 4 weeks old Nicotiana benthamiana plants, through the agroinfiltration method. Sanger sequencing indicated that the Cas12a-MV constructs made a considerable mutations at the target sites of the viral genome. In addition, TIDE analysis of Sanger sequencing results showed the editing efficiency of crRNA1 (21.7%), crRNA2 (24.9%) and crRNA3 (55.6%). Furthermore, the Cas12a-MV construct was stably transformed into Nicotiana tabacum through the leaf disc method to evaluate the potential of transgenic plants against CLCuMuV. For transgene analysis, the DNA of transgenic plants of Nicotiana tabacum was subjected to PCR to amplify Cas12a genes with specific primers. Infectious clones were agro-inoculated in transgenic and non-transgenic plants (control) for the infectivity assay. The transgenic plants containing Cas12a-MV showed rare symptoms and remained healthy compared to control plants with severe symptoms. The transgenic plants containing Cas12a-MV showed a significant reduction in virus accumulation (0.05) as compared to control plants (1.0). The results demonstrated the potential use of the multiplex LbCas12a system to develop virus resistance in model and crop plants against begomoviruses.
• Brown, J. K. (2023). Genome-Wide Identification of Cotton MicroRNAs Predicted for Targeting Cotton Leaf Curl Kokhran Virus-Lucknow. Microbiology Research, 15(1), 1-19. doi:10.3390/microbiolres15010001
• Brown, J. K. (2023). Grape pomace's potential on semi‐arid soil health enhances performance of maize, wheat, and grape crops. Journal of Plant Nutrition and Soil Science, 186(3), 276-285. doi:10.1002/jpln.202200232
• Brown, J. K. (2023). Identification and distribution of the “Candidatus Liberibacter asiaticus”-Asian citrus psyllid pathosystem in Saudi Arabia. Plant Disease, 107(3). doi:10.1094/pdis-07-23-1460-re
• Brown, J. K. (2023). In Silico Identification of Cassava Genome-Encoded MicroRNAs with Predicted Potential for Targeting the ICMV-Kerala Begomoviral Pathogen of Cassava. Viruses, 15(2), 486. doi:10.3390/v15020486
• Brown, J. K. (2023). Knowledge Gaps, Research Needs, and Opportunities in Plant Disease Diagnostics Assay Development and Validation. PhytoFrontiers™, 3(1), 51-63. doi:10.1094/phytofr-05-22-0057-fi
• Brown, J. K. (2023). Native and Non-Native Bemisia tabaci NAFME Haplotypes Can Be Implicated in Dispersal of Endemic and Introduced Begomoviruses in Oman. Insects, 14(3), 268. doi:10.3390/insects14030268
• He, R., Fisher, T. W., Saha, S., Peiz-Stelinski, K., Willis, M. A., Gang, D. R., & Brown, J. K. (2023). Differential gene expression of Asian citrus psyllids infected with ‘Ca. Liberibacter asiaticus’ reveals hyper-susceptibility to invasion by instar fourth-fifth and teneral adult stages. Frontiers in Plant Science, 14(Issue). doi:10.3389/fpls.2023.1229620
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  The bacterial pathogen Candidatus Liberibacter asiaticus (CLas) is the causal agent of citrus greening disease. This unusual plant pathogenic bacterium also infects its psyllid host, the Asian citrus psyllid (ACP). To investigate gene expression profiles with a focus on genes involved in infection and circulation within the psyllid host of CLas, RNA-seq libraries were constructed from CLas-infected and CLas-free ACP representing the five different developmental stages, namely, nymphal instars 1-2, 3, and 4-5, and teneral and mature adults. The Gbp paired-end reads (296) representing the transcriptional landscape of ACP across all life stages and the official gene set (OGSv3) were annotated based on the chromosomal-length v3 reference genome and used for de novo transcript discovery resulting in 25,410 genes with 124,177 isoforms. Differential expression analysis across all ACP developmental stages revealed instar-specific responses to CLas infection, with greater overall responses by nymphal instars, compared to mature adults. More genes were over-or under-expressed in the 4-5th nymphal instars and young (teneral) adults than in instars 1-3, or mature adults, indicating that late immature instars and young maturing adults were highly responsive to CLas infection. Genes identified with potential for direct or indirect involvement in the ACP-CLas circulative, propagative transmission pathway were predominantly responsive during early invasion and infection processes and included canonical cytoskeletal remodeling and endo-exocytosis pathway genes. Genes with predicted functions in defense, development, and immunity exhibited the greatest responsiveness to CLas infection. These results shed new light on ACP-CLas interactions essential for pathogenesis of the psyllid host, some that share striking similarities with effector protein-animal host mechanisms reported for other culturable and/or fastidious bacterial- or viral- host pathosystems.
• Iqbal, M. J., Zia-Ur-Rehman, M., Ilyas, M., Hameed, U., Herrmann, H. W., Chingandu, N., Manzoor, M. T., Haider, M. S., & Brown, J. K. (2023). Sentinel plot surveillance of cotton leaf curl disease in Pakistan- a case study at the cultivated cotton-wild host plant interface. Virus Research, 333(Issue). doi:10.1016/j.virusres.2023.199144
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  A sentinel plot case study was carried out to identify and map the distribution of begomovirus-betasatellite complexes in sentinel plots and commercial cotton fields over a four-year period using molecular and high-throughput DNA ‘discovery’ sequencing approaches. Samples were collected from 15 study sites in the two major cotton-producing areas of Pakistan. Whitefly- and leafhopper-transmitted geminiviruses were detected in previously unreported host plant species and locations. The most prevalent begomovirus was cotton leaf curl Kokhran virus-Burewala (CLCuKoV-Bu). Unexpectedly, a recently recognized recombinant, cotton leaf curl Multan virus-Rajasthan (CLCuMuV-Ra) was prevalent in five of 15 sites. cotton leaf curl Alabad virus (CLCuAlV) and cotton leaf curl Kokhran virus-Kokhran, ‘core’ members of CLCuD-begomoviruses that co-occurred with CLCuMuV in the ‘Multan’ epidemic were detected in one of 15 sentinel plots. Also identified were chickpea chlorotic dwarf virus and ‘non-core’ CLCuD-begomoviruses, okra enation leaf curl virus, squash leaf curl virus, and tomato leaf curl New Delhi virus. Cotton leaf curl Multan betasatellite (CLCuMuB) was the most prevalent CLCuD-betasatellite, and less commonly, two ‘non-core’ betasatellites. Recombination analysis revealed previously uncharacterized recombinants among helper virus-betasatellite complexes consisting of CLCuKoV, CLCuMuV, CLCuAlV and CLCuMuB. Population analyses provided early evidence for CLCuMuV-Ra expansion and displacement of CLCuKoV-Bu in India and Pakistan from 2012-2017. Identification of ‘core’ and non-core CLCuD-species/strains in cotton and other potential reservoirs, and presence of the now predominant CLCuMuV-Ra strain are indicative of ongoing diversification. Investigating the phylodynamics of geminivirus emergence in cotton-vegetable cropping systems offers an opportunity to understand the driving forces underlying disease outbreaks and reconcile viral evolution with epidemiological relationships that also capture pathogen population shifts.
• Marchant, W., Mugerwa, H., Gautam, S., Al-Aqeel, H., Polston, J., Rennberger, G., Smith, H., Turechek, B., Adkins, S., Brown, J., & Srinivasan, R. (2023). Phylogenomic and population genetics analyses of extant tomato yellow leaf curl virus strains on a global scale. Frontiers in Virology, 3, 1221156. doi:10.3389/fviro.2023.1221156
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  Tomato yellow leaf curl virus (TYLCV) is a monopartite DNA virus with a genome size of ~ 2,800 base pairs. The virus belongs to the genus Begomovirus within the family Geminiviridae. Extant TYLCV strains are differentiated based on an established threshold of 94% genome-wide pairwise nucleotide identity. The phylogenetic relationships, diversification mechanisms, including recombination, and extent of spread within and from the center of origin for TYLCV have been reported in previous studies. However, the evolutionary relationships among strains, strains’ distribution and genomic diversification, and genetic mechanisms shaping TYLCV strains’ evolution have not been re-evaluated to consider globally representative genome sequences in publicly available sequence database, including herein newly sequenced genomes from the U.S. and Middle East, respectively. In this study, full-length genome sequences for the extant strains and isolates of TYLCV (n=818) were downloaded from the GenBank database. All previously published genome sequences, and newly sequenced TYLCV genomes of TYLCV isolates from Kuwait and USA, determined herein (n=834), were subjected to recombination analysis. To remove the ‘phylogenetic noise’ imparted by interspecific recombination, the recombinant genomes were removed from the data set, and the remaining non-recombinant genome sequences (n=423) were subjected to population genetics and Bayesian analyses. Results of the phylogeographical analysis indicated that the type strain, TYLCV-Israel, and TYLCV-Mild strain, were globally distributed, spanning Africa, America, Asia, Australia/Oceania, Europe, and New Caledonia, while the other TYLCV strains were prevalent only throughout the Middle East. The results of Bayesian evolutionary (ancestral) analysis predicted that TYLCV-Israel represents the oldest, most recent common ancestor (MRCA) (41,795 years), followed by TYLCV-Mild at 39,808 years. These were closely followed by two Iranian strains viz., TYLCV-Kerman and TYLCV-Iran at 37,529 and 36,420 years, respectively. In contrast, the most recently evolving strains were TYLCV-Kuwait and TYLCV-Kahnooj at 12,445 and 298 years, respectively. Results of the neutrality test indicated that TYLCV-Israel and TYLCV-Mild populations are undergoing purifying selection and/or population expansion, although statistically significant selection was documented for only TYLCV-Israel, based on positive selection acting on five codons.
• Mpanga, I., Neumann, G., Brown, J., Blankinship, J., Tronstad, R., & Idowu, O. (2023). Grape pomace's potential on semi-arid soil health enhances performance of maize, wheat, and grape crops. Journal of Plant Nutrition and Soil Science, 186(3), 76–285.2. doi:10.1002/jpln.202200232
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  Background: Grape pomace (GP) is a by-product of wineries after filtering the grape juice for wine production. GP contains seeds, pulp, skin, and stalks with acidic properties, and it is normally composted before using as a soil amendment. However, composting GP requires more time, labor, and equipment; furthermore, composting loses some of the desirable organic acids for arid soils. The acidic properties of these organic acids and the plant nutrients in GP make it a desirable amendment for arid soils in both non-composted and composted forms. Aim: This study investigates the potential of directly applying GP as a soil amendment and its impact on arid soil health and plant performance. Methods: To test the potential of non-composted GP as a soil amendment, greenhouse and field studies were conducted by combining GP with existing management practices (manure application for soil used in the greenhouse study and fertigation for the field study) to assess the effects of GP on soil health and crop (maize, wheat, and grape) performance. Results: Adding 5% GP to an alkaline soil significantly increased maize and wheat growth and shoot nutrient concentrations in the greenhouse and grapes in the field (48% yield increase). The significance of GP on maize, wheat, and grapes was associated with soil nutrient enhancements (i.e., nutrients supplied, increase in organic matter and microbial biomass increase, reduction in pH, and better nutrient mobilization). Conclusion: GP has the potential for direct use as a soil amendment for soil and crop health improvement, especially in arid soils with high pH and limited soil organic matter.
• Shahid, M., Paredes-Montero, J., Ashfaq, M., Al-Sadi, A., & Brown, J. (2023). Native and Non-Native Bemisia tabaci NAFME Haplotypes Can Be Implicated in Dispersal of Endemic and Introduced Begomoviruses in Oman. Insects, 14(3). doi:10.3390/insects14030268
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  Irrigated agriculture and global trade expansion have facilitated diversification and spread of begomoviruses (Geminiviridae), transmitted by the Bemisia tabaci (Gennadius) cryptic species. Oman is situated on major crossroads between Africa and South Asia, where endemic/native and introduced/exotic begomoviruses occur in agroecosystems. The B. tabaci ‘B mitotype’ belongs to the North Africa–Middle East (NAFME) cryptic species, comprising at least eight endemic haplotypes, of which haplotypes 6 and/or 8 are recognized invasives. Prevalence and associations among native and exotic begomoviruses and NAFME haplotypes in Oman were investigated. Nine begomoviral species were identified from B. tabaci infesting crop or wild plant species, with 67% and 33% representing native and exotic species, respectively. Haplotypes 2, 3, and 5 represented 31%, 3%, and 66% of the B. tabaci population, respectively. Logistic regression and correspondence analyses predicted ‘strong’- and ‘close’ virus–vector associations involving haplotypes 5 and 2 and the exotic chili leaf curl virus (ChiLCV) and endemic tomato yellow leaf curl virus-OM, respectively. Patterns favor a hypothesis of relaxed virus–vector specificity between an endemic haplotype and the introduced ChiLCV, whereas the endemic co-evolved TYLCV-OM and haplotype 2 virus–vector relationship was reinforced. Thus, in Oman, at least one native haplotype can facilitate the spread of endemic and introduced begomoviruses.
• Thakre, N., Carver, M., Paredes-Montero, J., Mondal, M., Hu, J., Saberi, E., Qureshi, J., & Brown, J. K. (2023). UV Laser-adjuvant-surfactant-facilitated delivery of mobile dsRNA to tomato plant vasculature and evidence of biological activity by knockdown in the potato psyllid. Journal of Pest Science. doi:doi 10.1002/ps.7952
• Widyawan, A., Ibrahim, Y. E., Komy, M. H., Al Dhafer, H. M., Brown, J. K., & Al-Saleh, M. A. (2023). Differentiation of ‘Candidatus Liberibacter asiaticus’ in Saudi Arabia based on tandem repeat variability in genomic locus. Journal of King Saud University - Science, 35(Issue 1). doi:10.1016/j.jksus.2022.102376
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  Citrus greening, or huanglongbing, is a destructive disease threatening many citrus worldwide, and drastically altering the global dynamics of the citrus industry. The disease is caused by one of several unculturable bacterial species belonging to ‘Candidatus Liberibacter’. The recent availability of complete genome sequences of ‘Candidatus Liberibacter asiaticus’ (CLas) has facilitated comprehensive assessments of genomic variability using a range of approaches, including short tandem repeat analysis. The objective of this study was to evaluate the genetic diversity of CLas populations in Saudi Arabia based on tandem repeat number (TRN) within the CLIBASIA_01645 locus, predicted to encode the bacteriophage C1 repressor protein. Results indicated that the genotype richness of the Saudi Arabian CLas isolates was conserved by 27% based on the TRN locus. Four different genotypes TRN2, TRN3, TRN4, and TRN5 were identified. However, the TRN2 and TRN5 were the most dominant genotypes. All four of the TRN genotypes were associated with CLas-positive mandarin (Citrus reticulata) or sweet orange (C. sinensis) citrus trees. The diversity (H = 0.69) and evenness (H'=0.914) were overall relatively high, with the northern region of Saudi Arabia harboring the highest diversity (0.7) and evenness score (0.9–1.0). Phylogenetic analysis of the CLas-bacteriophage C1 repressor protein of the Saudi Arabian isolates indicated CLas was more closely related to ‘Candidatus Liberibacter africanus’ than to ‘Candidatus Liberibacter americanus’.
• Ashraf, M. A., Shahid, A. A., Rao, A. Q., Brown, J. K., & Husnain, T. (2022). Development and Evaluation of the Cotton Leaf Curl Kokhran Virus-Burewala Bidirectional Promoter for Enhanced Cry1Ac Endotoxin Expression in Bt Transgenic Cotton. Applied Sciences (Switzerland), 12(Issue 21). doi:10.3390/app122111275
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  Fluctuation in Cry1Ac endotoxin levels expressed in transgenic Bacillus thuringiensis (Bt) cotton (Gossypium hirsutum L.) can result in a variation in efficacy throughout the growing season. Here, a green tissue-specific strong promoter of the cotton leaf curl Kokhran virus-Burewala (CLCuKoV-Bu) C1 gene is reported that can direct consistently high levels of Cry1Ac endotoxin expression in transformed cotton plants. The objective of this study was to investigate the capacities of the CLCuKoV-BuC1 promoter to drive transcription of Cry1Ac and stably express endotoxin in mature leaves and bolls of transgenic cotton plants, compared to the traditional CaMV35S promoter. The Cry1Ac gene expression cassettes were constructed under the control of a bidirectional promoter and transformed into cotton ‘MNK-786′. The expression of Cry1Ac constructs was evaluated in transient and stable expression systems using Nicotiana tabacum ‘Rustica’ and cotton plants, respectively. Accumulation of the Cry1Ac expressed in two resultant transgenic cotton plants harboring the constructs driven by the CLCuKoV-BuC1 and CaMV35S promoter, respectively, was analyzed using a commercially available enzyme-linked immunosorbent assay. In leaves and bolls of two cotton plants shown to express CLCuKoV-BuC1-Cry1Ac (CLCuV-Ac), the Cry1Ac protein accumulated at 400 and 300 ng g−1 per fresh tissue weight, respectively, whereas no toxin was detectable in the roots. In contrast, CaMV35S-Cry1Ac transgenic cotton plants accumulated three times less Cry1Ac protein than those transformed with CLCuV-Ac. Results indicate that the greatest amount of Cry1Ac endotoxin accumulated in transgenic cotton when expression was driven by the CLCuKoV-BuC1 compared to the CaMV35S promoter. Thus, the CLCuKoV-BuC1 promoter offered more robust transgene expression in cotton plants than the traditional CaMV35S promoter. The newly validated CLCuV-Ac promoter of begomoviral origin offers an exciting alternative as a robust promoter for genetic engineering of cotton and other plants.
• Bock, C. H., Brown, J. K., Cubero, J., Pierson, E. A., Roper, C., & Wang, N. (2022). ‘Candidatus Liberibacter’ Pathosystems at the Forefront of Agricultural and Biological Research Challenges. Phytopathology, 112(1), 7-10. doi:10.1094/phyto-12-21-0497-fi
• Brown, J. K. (2019). Analysis of 82 genomes associated with a global complex of badnavirus species infecting cacao reveals mixed infections, extensive genomic variability, and interspecific recombination.. Viruses.
• Brown, J. K. (2019). Association between algal productivity and phycosphere composition in an outdoor Chlorella sorokiniana reactor based on multiple longitudinal analyses. Microbiome.
• Brown, J. K. (2019). Discrimination of Bemisia tabaci (Hemiptera: Aleyrodidae) species variants and Trialeurodes vaporariorum using real-time melting curve analysis and helicase dependent amplification.. J. Econ. Entomol., 113(5), 2511-2520. doi:https://doi.org/10.1093
• Brown, J. K. (2019). Genetic variability, community structure, and horizontal transfer of Arsenophonus OTUs among three Asia II-Bemisia tabaci mitotypes in Pakistan.. Ecol. and Evol..
• Brown, J. K. (2019). Metabolic resistance to organophosphate insecticides in laboratory and field populations of the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) in Egypt.. J. Econ. Entomol..
• Brown, J. K. (2019). Phylo-biogeographical distribution of whitefly Bemisia tabaci mitotypes in Ecuador. Ecosphere.
• Brown, J. K. (2020). Distribution of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) mitotypes in commercial cotton fields in the Punjab province of Pakistan.. Florida Entomologist, in press.
• Brown, J. K. (2022). A molecular study on African cassava mosaic disease management in Côte d’Ivoire. Int. J. Plant Pathol, 14, 1-12. doi:10.3923/ijpp.2023.1.12
• Brown, J. K. (2022). Association of tomato yellow leaf curl virus - Oman strain with the leaf curl and yellow mosaic symptoms on papaya and wild poinsettia in Oman. Can. J. Phytopathol, 44(3), 465-472. doi:Doi 10.1080/07060661.2021.1995500
• Brown, J. K. (2022). Auxenochlorella protothecoides populations adapted to low phosphate conditions accumulated more non-phosphorus glycerolipids and biomass than wild type progenitors.. Plant Stress, 6, 1000115. doi:10.1016/j.stress.2022.100115
• Brown, J. K. (2022). Comparison of Auxenochlorella protothecoides and Chlorella spp. Chloroplast genomes: Evidence for endosymbiosis and horizontal virus-like gene transfer. Life, 12, 458. doi:10.3390/life12030458
• Brown, J. K. (2022). Development and Evaluation of the Cotton leaf curl Kokhran virus-Burewala bidirectional promoter for enhanced Cry1Ac endotoxin expression in Bt transgenic cotton. . Appl. Sci., 12, 11275. doi:https://doi.org/10.3390/app 122111275
• Brown, J. K. (2022). Differential transcriptional responses in two Old World Bemisia tabaci cryptic species post acquisition of Old and New World begomoviruses. Cells, 11, 2060. doi:https://doi.org/10.3390/cells11132060
• Brown, J. K. (2022). Differentiation of ‘Candidatus Liberibacter asiaticus’ in Saudi Arabia based on tandem repeat variability in genomic locus. J. King Saud Univ, 35(1), 102376. doi:10.1016/j.jksus.2022.102376
• Brown, J. K. (2022). Earlier than expected introductions of the Bemisia tabaci B mitotype in Brazil. Ecol and Evol, 12:e8557. doi:https://doi.org/10.1002/ece3.8557
• Brown, J. K. (2022). Monitoring insecticide resistance in Bemisia tabaci (Hemiptera: Aleyrodidae) field populations in the Punjab Province of Pakistan. Heliyon, 8(12), e12010.
• Brown, J. K. (2022). RNA interference-mediated knockdown of genes implicated in the synthesis of ecdysteroids, impairs molting in the potato psyllid, Bactericera cockerelli (Insecta: Hemiptera). Pest Mgmt. Sci., 78(6), 2204-2214. doi:10.1002/ps.6848
• Brown, J. K. (2022). Soil-health assessment of three semi-arid soil textures in an Arizona vineyard irrigated with reclaimed municipal water. . Water, 14(8). doi:10.3390/w14182922
• Brown, J. K., Adegbola, R. O., Keith, C. V., Gutierrez, O. A., & Goenaga, R. (2022). A Previously Undescribed Polerovirus (Solemoviridae) Infecting Theobroma cacao Germplasm. Plant Disease. doi:10.1094/pdis-06-22-1449-pdn
• Haq, Q. M., Haq, Q. M., Sohrab, S. S., Sohrab, S. S., Brown, J. K., Brown, J. K., Al-Harrasi, A., & Al-Harrasi, A. (2022). Association of tomato yellow leaf curl virus — Oman strain with the leaf curl and yellow mosaic symptoms on papaya and wild poinsettia in Oman. Canadian Journal of Plant Pathology, 44(Issue 3). doi:10.1080/07060661.2021.1995500
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  Begomoviruses (Geminiviridae) cause severe diseases in several crops, often causing significant losses due to reduced yield and quality. These viruses are easily transmitted by the whitefly (Bemisia tabaci) vector. Begomovirus-like symptoms were observed in wild poinsettia (Euphorbia cyathophora) and cultivated papaya (Carica papaya) plants in the Nizwa, Al-Dakhliya and Al-Batinah regions of Oman, where papaya is grown extensively. The aim of this study was to identify the suspected viral causal agent associated with yellow mosaic and leaf curl symptoms in the poinsettia and papaya plants. Symptomatic leaf samples were collected and subjected to DNA isolation followed by PCR amplification with begomovirus-coat protein specic primers. An amplicon of betasatellites was also amplified using betasatellite-specific primers. The amplicons were cloned and sequenced bi-directionally. The full-length begomoviral genome was determined to be 2766 and 2752 bp in length for the wild poinsettia and papaya isolates, respectively. The respective betasatellites were found to be 1354 and 1370 bp. Sequence analysis indicated that the papaya isolate, herein tomato yellow leaf curl virus (TYLCV)-Pap-Oman, shared 95.0% nucleotide identity with the wild poinsettia isolate, herein TYLCV-Poin-Oman, followed by 93.5% identity with TYLCV-Iran (GU076448). Phylogenetic analysis grouped TYLCV-Pap-Oman and TYLCV-Poin-Oman with TYLCV isolates previously reported from Iran, Saudi Arabia and Sudan, whereas the two betasatellites grouped them with TYLCB isolates previously reported from Oman. Based on the nucleotide sequence identity and phylogenetic tree analysis, the Begomovirus identified from papaya and wild poinsettia is considered an isolate of TYLCV from plant host species previously reported in the Arabian Peninsula.
• Ibrahim, Y., Paredes-Montero, J., Al-Saleh, M., Widyawan, A., He, R., El Komy, M., Al Dhafer, H., Kitchen, N., Gang, D., & Brown, J. (2022). Characterization of the Asian Citrus Psyllid-‘Candidatus Liberibacter Asiaticus’ Pathosystem in Saudi Arabia Reveals Two Predominant CLas Lineages and One Asian Citrus Psyllid Vector Haplotype. Microorganisms, 10(10), 1991. doi:10.3390/microorganisms10101991
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  In Saudi Arabia (SA), the citrus greening disease is caused by ‘Candidatus Liberibacter asiaticus’ (CLas) transmitted by the Asian citrus psyllid (ACP) Diaphorina citri. The origin and route(s) of the ACP-CLas pathosystem invasion in SA have not been studied. Adult ACP were collected from citrus trees in SA and differentiated by analysis of the mitochondrial cytochrome oxidase I (mtCOI) and nuclear copper transporting protein (atox1) genes. A phylogenetic analysis of the Wolbachia spp. surface protein (wsp) gene was used to identify the ACP-associated Wolbachia spp. A phylogenetic analysis of the atox1 and mtCOI gene sequences revealed one predominant ACP haplotype most closely related to the Indian subcontinent founder populations. The detection and identification of CLas in citrus trees were carried out by polymerase chain reaction (PCR) amplification and sequencing of the 16S rDNA gene. The CLas-integrated prophage genomes were sequenced, annotated, and used to differentiate CLas populations. The ML and ASTRAL trees reconstructed with prophages type 1 and 2 genome sequences, separately and concatenated, resolved two major lineages, CLas-1 and -2. The CLas-1 clade, reported here for the first time, consisted of isolates from SA isolates and Pakistan. The CLas-2 sequences formed two groups, CLas-2-1 and -2-2, previously the ‘Asiatic’ and ‘Floridian’ strains, respectively. Members of CLas-2-1 originated from Southeast Asia, the USA, and other worldwide locations, while CLas-2-2 was identified only in Florida. This study provides the first snapshot into the status of the ACP-CLas pathosystem in SA. In addition, the results provide new insights into the pathosystem coevolution and global invasion histories of two ACP-CLas lineages with a predicted center of origin in South and Southeast Asia, respectively.
• Mondal, M., Carver, M., & Brown, J. (2022). Characteristics of environmental RNAi in potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Psylloidea: Triozidae). Frontiers in Physiology, 13, 931951. doi:10.3389/fphys.2022.931951
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  RNA interference (RNAi) has potential to become a major tool for integrated management of insect pests of agricultural crops based on sequence-specificity and low doses of rapidly biodegradable dsRNA. Deploying ‘environmental RNAi’ for control of insect vectors of plant pathogens is of increasing interest for combatting emerging plant diseases. Hemipteran insect vectors, including psyllids, are vascular feeders, making their development difficult to control specifically by targeting with pesticidal chemistries. Psyllids transmit “Candidatus Liberibacter solanacearum” the causal organism of potato zebra chip and tomato vein greening diseases, transmitted, respectively, by the potato or tomato psyllid (PoP). Until now, the optimal effective concentration(s) of double-stranded RNA (dsRNA) required for significant gene knockdown and RNAi persistence in PoP have not been determined. The objective of this study was to optimize RNAi in young PoP adults and 3rd instars for screening by oral delivery of dsRNAs. The minimal effective dsRNA concentrations required for robust knockdown and persistence were evaluated by delivering seven concentrations spanning 0.1 ng/μL to 500 ng/μL over post ingestion-access periods (IAP) ranging from 48 h to 12 days. The PoP gene candidates evaluated as targets were vacuolar ATPase subunit A, clathrin heavy chain, and non-fermenting protein 7, which were evaluated for knockdown by qPCR amplification. The minimum and/or the second most effective dsRNA concentration resulting in effective levels of gene knockdown was 100 ng/μL for all three targets. Higher concentrations did not yield further knockdown, indicating potential RISC saturation at the higher doses. Gene silencing post-IAP of 100 ng/μL dsRNA persisted for 3–5 days in adults and nymphs, with the PoP 3rd instar, followed by teneral and mature adults, respectively, exhibiting the most robust RNAi-response.
• Mpanga, I. K., Sserunkuma, H., Tronstad, R., Pierce, M., & Brown, J. K. (2022). Soil Health Assessment of Three Semi-Arid Soil Textures in an Arizona Vineyard Irrigated with Reclaimed Municipal Water. Water (Switzerland), 14(Issue 18). doi:10.3390/w14182922
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  The depletion of freshwater supply is occurring at a faster rate than it is being replenished. The agriculture sector is the largest consumer of freshwater for irrigation and production-related processes. The use of reclaimed municipal water for the irrigation of crops offers a sustainable alternative solution for reducing the dependence of agriculture on freshwater. However, the long-term and continuous use of reclaimed water may contribute to soil salinity and sodicity limitations in agriculture production. The chemical and microbial properties of three different soil textures (all Alluvial soil with 60% clay: pH 8.6; 30% clay: pH 8.2; and 20% clay: pH 7.9) were evaluated in a vineyard irrigated using reclaimed water (126 mg/L Na+, 154 mg/L Cl−, 7.6 water pH, and 1.2 dS/m ECw). The results indicate that the reclaimed irrigation water significantly (p < 0.05) increased the pH (by 0.4 to 18%), nitrate-N (over 100%), electrical conductivity (EC) (over 100%), and sodium absorption ratio (SAR) in these arid soils. A significant decline in microbial respiration (48 to 80%) was also documented in the three different soil textures that received reclaimed water. Although using reclaimed water for crop irrigation may be a substitute for using limited freshwater resources and offer a partial solution to increasing water security for wine grape production, the development of innovative technologies is needed for the long-term use of reclaimed water to counter its undesirable effects on soil quality.
• Mugerwa, H., Gautam, S., Catto, M. A., Dutta, B., Brown, J. K., Adkins, S., & Srinivasan, R. (2022). Differential Transcriptional Responses in Two Old World Bemisia tabaci Cryptic Species Post Acquisition of Old and New World Begomoviruses. Cells, 11(Issue 13). doi:10.3390/cells11132060
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  Begomoviruses are transmitted by several cryptic species of the sweetpotato whitefly, Bemisia tabaci (Gennadius), in a persistent and circulative manner. Upon virus acquisition and circulative translocation within the whitefly, a multitude of molecular interactions occur. This study investigated the differentially expressed transcript profiles associated with the acquisition of the Old World monopartite begomovirus, tomato yellow leaf curl virus (TYLCV), and two New World bipartite begomoviruses, sida golden mosaic virus (SiGMV) and cucurbit leaf crumple virus (CuLCrV), in two invasive B. tabaci cryptic species, Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED). A total of 881 and 559 genes were differentially expressed in viruliferous MEAM1 and MED whiteflies, respectively, compared with their non-viruliferous counterparts, of which 146 genes were common between the two cryptic species. For both cryptic species, the number of differentially expressed genes (DEGs) associated with TYLCV and SiGMV acquisition were higher compared with DEGs associated with CuLCrV acquisition. Pathway analysis indicated that the acquisition of begomoviruses induced differential changes in pathways associated with metabolism and organismal systems. Contrasting expression patterns of major genes associated with virus infection and immune systems were observed. These genes were generally overexpressed and underexpressed in B. tabaci MEAM1 and MED adults, respectively. Further, no specific expression pattern was observed among genes associated with fitness (egg production, spermatogenesis, and aging) in viruliferous whiteflies. The weighted gene correlation network analysis of viruliferous B. tabaci MEAM1 and MED adults identified different hub genes potentially implicated in the vector competence and circulative tropism of viruses. Taken together, the results indicate that both vector cryptic species and the acquired virus species could differentially affect gene expression.
• Paredes-Montero, J. R., Arif, U., & Brown, J. K. (2022). Knockdown of ecdysteroid synthesis genes results in impaired molting and high mortality in Bactericera cockerelli (Hemiptera: Triozidae). Pest Management Science, 78(Issue 6). doi:10.1002/ps.6848
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  BACKGROUND: RNA-mediated interference (RNAi) has become a promising biopesticide technology with which to direct sequence-specific gene knockdown of key targets in the potato psyllid (PoP) Bactericera cockerelli, resulting in significant mortality. In this study, three strategically selected target genes, ATF4, C7 and D24, essential for the biosynthesis and regulation of ecdysteroids, were evaluated for knockdown and mortality using oral delivery of individual, paired and all three double-stranded RNAs (dsRNAs), in five replicated experiments. Knockdown was determined as the fold-change in gene expression using a quantitative polymerase chain reaction. RESULTS: Knockdown of the D24 target, at 39%–45%, resulted in 51% PoP mortality by 10 days post-ingestion (dpi) of dsRNA. Knockdown of C7, at 38%–61%, resulted in 53% mortality by 10 dpi, whereas dsD24 ingestion resulted in 65% mortality by 10 dpi when dsD24 and dsC7 were co-delivered. Three phenotypes, INCOMEC, PREMEC and SWOLLEN, were observed at a frequency of 4%–12%, and are consistent with incomplete ecdysis in immature and/or adult PoP. Adult PoP exhibiting INCOMEC survived for several days but were unable to mate or fly, whereas SWOLLEN and PREMEC were lethal to the immature instars. Knockdown of ATF4 did not result in the mortality or malformations in immature and adult PoP. CONCLUSIONS: Compared with knockdown of individual D24 and C7 targets, significantly greater RNAi penetrance was achieved following delivery of combined dsRNAs. The highest knockdown that resulted in incomplete ecdysis and/or mortality was obtained for targets with predicted involvement in the same or interacting pathway(s). Knockdown of ATF4 was apparently “rescued” by uncharacterized compensatory gene(s) or effects. © 2022 Society of Chemical Industry.
• Paredes-Montero, J. R., Rizental, M., Quintela, E. D., Abreu, A. G., & Brown, J. K. (2022). Earlier than expected introductions of the Bemisia tabaci B mitotype in Brazil reveal an unprecedented, rapid invasion history. Ecology and Evolution, 12(Issue 1). doi:10.1002/ece3.8557
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  During 1991, in Brazil, the presence of the exotic Bemisia tabaci B mitotype was reported in São Paulo state. However, the duration from the time of initial introduction to population upsurges is not known. To investigate whether the 1991 B mitotype outbreaks in Brazil originated in São Paulo or from migrating populations from neighboring introduction sites, country-wide field samples of B. tabaci archived from 1989–2005 collections were subjected to analysis of mitochondrial cytochrome oxidase I (mtCOI) and nuclear RNA-binding protein 15 (RP-15) sequences. The results of mtCOI sequence analysis identified all B. tabaci as the NAFME 8 haplotype of the B mitotype. Phylogenetic analyses of RP-15 sequences revealed that the B mitotype was likely a hybrid between a B type parent related to a haplotype Ethiopian endemism (NAFME 1–3), and an unidentified parent from the North Africa-Middle East (NAF-ME) region. Results provide the first evidence that this widely invasive B mitotype has evolved from a previously undocumented hybridization event. Samples from Rio de Janeiro (1989) and Ceará state (1990), respectively, are the earliest known B mitotype records in Brazil. A simulated migration for the 1989 introduction predicted a dispersal rate of 200–500 km/year, indicating that the population was unlikely to have reached Ceará by 1990. Results implicated two independent introductions of the B mitotype in Brazil in 1989 and 1990, that together were predicted to have contributed to the complete invasion of Brazil in only 30 generations.
• Park, S. H., Kyndt, J. A., & Brown, J. K. (2022). Comparison of Auxenochlorella protothecoides and Chlorella spp. Chloroplast Genomes: Evidence for Endosymbiosis and Horizontal Virus-like Gene Transfer. Life, 12(Issue 3). doi:10.3390/life12030458
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  Resequencing of the chloroplast genome (cpDNA) of Auxenochlorella protothecoides UTEX 25 was completed (GenBank Accession no. KC631634.1), revealing a genome size of 84,576 base pairs and 30.8% GC content, consistent with features reported for the previously sequenced A. protothecoides 0710, (GenBank Accession no. KC843975). The A. protothecoides UTEX 25 cpDNA encoded 78 predicted open reading frames, 32 tRNAs, and 4 rRNAs, making it smaller and more compact than the cpDNA genome of C. variabilis (124,579 bp) and C. vulgaris (150,613 bp). By comparison, the compact genome size of A. protothecoides was attributable primarily to a lower intergenic sequence content. The cpDNA coding regions of all known Chlorella species were found to be organized in conserved colinear blocks, with some rearrangements. The Auxenochlorella and Chlorella species genome structure and composition were similar, and of particular interest were genes influencing photosynthetic efficiency, i.e., chlorophyll synthesis and photosystem subunit I and II genes, consistent with other biofuel species of interest. Phylogenetic analysis revealed that Prototheca cutis is the closest known A. protothecoides relative, followed by members of the genus Chlorella. The cpDNA of A. protothecoides encodes 37 genes that are highly homologous to representative cyanobacteria species, including rrn16, rrn23, and psbA, corroborating a well-recognized symbiosis. Several putative coding regions were identified that shared high nucleotide sequence identity with virus-like sequences, suggestive of horizontal gene transfer. Despite these predictions, no corresponding transcripts were obtained by RT-PCR amplification, indicating they are unlikely to be expressed in the extant lineage.
• Saleem, M., Hussain, D., Hasan, M. u., Sagheer, M., Ghouse, G., Zubair, M., Brown, J. K., & Cheema, S. A. (2022). Differential insecticide resistance in Bemisia tabaci (Hemiptera: Aleyrodidae) field populations in the Punjab Province of Pakistan. Heliyon, 8(Issue 12). doi:10.1016/j.heliyon.2022.e12010
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  The cotton whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) has a propensity for developing high-level resistance to insecticides. Management of B. tabaci in cotton grown in Pakistan depends on insecticide use, resistance monitoring has become essential to minimize the development of resistance. In this study, resistance was monitored in adult whiteflies collected from cotton fields in the Bahawalpur, Faisalabad, Lodhran, Multan, and Vehari districts of the Punjab Province, Pakistan during 2017, 2018, and 2019. Resistance monitoring was carried out for two insect growth regulators (pyriproxyfen and buprofezin) four neonicotinoids acetamiprid, imidacloprid, thiamethoxam, thiacloprid, and the historically used pyrethroid, bifenthrin and organophosphate, chlorpyrifos. Results based on resistance ratio (RR) showed that moderate to high level of resistance against noenicitinoids insecticides have been observed in all four districts while whiteflies exhibited very low to low resistance to pyriproxyfen and buprofezin. The RRs for acetamiprid, imidacloprid, thiamethoxam, thiacloprid varied from 7.60 to 50.99, 19.32 to 65.72, 17.18 to 54.65 and 6.49–47.49-fold, respectively. Bifenthrin and chlorpyrifos showed very low toxicity against whiteflies in all districts except Faisalabad, with RRs of 12.28–50.56-fold and 7.94–26.24-fold, respectively. The results will facilitate ‘smart’ selection and guide rates of insecticide applications for whitefly management in cotton for effective whitefly management while also delaying the development of resistance.
• Steichen, S. A., Berim, A., Gang, D. R., & Brown, J. K. (2022). Auxenochlorella protothecoides populations adapted to low phosphate conditions accumulated more non-phosphorus glycerolipids and biomass than wild type progenitors. Plant Stress, 6(Issue). doi:10.1016/j.stress.2022.100115
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  Biodiesel produced by microalgae has great potential as a portable energy that can replace traditional hydrocarbon sources. One limitation of scaling up algal cultivation is the availability of macronutrients, particularly inorganic phosphate (Pi), which is a finite and dwindling resource. Here, Auxenochlorella protothecoides was adapted to low Pi conditions by continuous cultivation in growth media containing 100 times less Pi (17.15 µM PO4) than replete media for ∼ 40 generations. The low Pi-adapted A. protothecoides populations showed significantly higher growth rates, compared to wild type (WT) (natural, non-mutated) progenitor populations in batch experiments, with average maximum growth rates of 0.72 d−1 and 0.54 d−1, respectively. Total lipid profiling of the adapting A. protothecoides populations indicated a shift to non-phosphorus glycerolipids, based on UPLC/MS analyzes. The proportions of monogalactosyldiacylglycerol (MGDG) and sulfoquinovosyldiacyglycerol (SQDG) fluctuated during adaptation, accumulating 305% and 317% of the WT levels respectively by the final sampling. Time-course transcriptome profiling of A. protothecoides across all adaptation stages revealed initial increases in transcript levels, followed by global decreased expression. The short-term transcriptomic changes, prior to ∼ 11 generations, were associated with major metabolic pathways. The long-term changes indicated increased fatty acid turnover and a decrease in photosynthesis-related gene expression. Transcripts predicted to encode alternative oxidase and pyrophosphate-dependent phosphofructokinase fluctuated during adaptation. The selection of A. protothecoides under low Pi conditions resulted in a microalga variant that after only ∼40 generations utilized Pi more efficiently for growth than its wild type progenitor population, while also producing 1.22 times more biomass. The adaptive processes described herein produced commercially relevant strain material and provide avenues for future, targeted engineering of molecular pathways for increased Pi use efficiency in similar organisms.
• , ., Kuhn, J. H., Adkins, S., Agwanda, B. R., Al Kubrusli, R., Alkhovsky, S. V., Amarasinghe, G. K., Avšič-Županc, T., Ayllón, M. A., Bahl, J., Balkema-Buschmann, A., Ballinger, M. J., Basler, C. F., Bavari, S., Beer, M., Bejerman, N., Bennett, A. J., Bente, D. A., Bergeron, É., , Bird, B. H., et al. (2021). 2021 Taxonomic update of phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales. Archives of Virology, 166(Issue 12). doi:10.1007/s00705-021-05143-6
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  In March 2021, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. The phylum was expanded by four families (Aliusviridae, Crepuscuviridae, Myriaviridae, and Natareviridae), three subfamilies (Alpharhabdovirinae, Betarhabdovirinae, and Gammarhabdovirinae), 42 genera, and 200 species. Thirty-nine species were renamed and/or moved and seven species were abolished. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.
• , ., Kuhn, J. H., Adkins, S., Agwanda, B. R., Al Kubrusli, R., Alkhovsky, S. V., Amarasinghe, G. K., Avšič-Županc, T., Ayllón, M. A., Bahl, J., Balkema-Buschmann, A., Ballinger, M. J., Basler, C. F., Bavari, S., Beer, M., Bejerman, N., Bennett, A. J., Bente, D. A., Bergeron, É., , Bird, B. H., et al. (2021). Correction to: 2021 Taxonomic update of phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales (Archives of Virology, (2021), 166, 12, (3513-3566), 10.1007/s00705-021-05143-6). Archives of Virology, 166(Issue 12). doi:10.1007/s00705-021-05266-w
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  Unfortunately, the inclusion of original names (in non-Latin script) of the following authors caused problems with author name indexing in PubMed. Therefore, these original names were removed from XML data to correct the PubMed record. Mengji Cao, Yuya Chiaki, Hideki Ebihara, Jingjing Fu, George Fú Gāo, Tong Han, Jiang Hong, Ni Hong, Seiji Hongo, Masayuki Horie, Dàohóng Jiāng, Fujio Kadono, Hideki Kondō, Kenji Kubota, Shaorong Li, Longhui Li, Jiànróng Lǐ, Huazhen Liu, Tomohide Natsuaki, Sergey V. Netesov, Anna Papa, Sofia Paraskevopoulou, Liying Qi, Takahide Sasaya, Mang Shi, Xiǎohóng Shí, Zhènglì Shí, Yoshifumi Shimomoto, Jin‑Won Song, Ayato Takada, Shigeharu Takeuchi, Yasuhiro Tomitaka, Keizō Tomonaga, Shinya Tsuda, Changchun Tu, Tomio Usugi, Nikos Vasilakis, Jiro Wada, Lin‑Fa Wang, Guoping Wang, Yanxiang Wang, Yaqin Wang, Tàiyún Wèi, Shaohua Wen, Jiangxiang Wu, Lei Xu, Hironobu Yanagisawa, Caixia Yang, Zuokun Yang, Lifeng Zhai, Yong‑Zhen Zhang, Song Zhang, Jinguo Zhang, Zhe Zhang, Xueping Zhou. In addition, the publication call-out in the supplementary material was updated from issue 11 to issue 12. The original article has been corrected.
• Brown, J. K. (2021). Construction of an infectious clone of the badnavirus Cacao swollen shoot Ghana M virus and infectivity by gene gun- and Agrobacterium-mediated inoculation.. Front. Agron., 3, 774863.. doi:https://doi.org/10.3389/fagro.2021.774863
• Brown, J. K. (2021). Taxonomic update of Phylum Negarnaviricota (Riboviria: Orthornavirae), including the largest orders, Bunyavirales and Mononegavirales. Arch Virol.. doi:doi: 10.1007/s00705-021-05143-6.
• Brown, J. K. (2021). Taxonomic update of Phylum Negarnaviricota (Riboviria: Orthornavirae), including the largest orders, Bunyavirales and Mononegavirales.. Arch Virol, Aug31. doi:doi: 10.1007/s00705-021-05143-6. Epub PMID: 34463877.
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  Kuhn JH, Adkins S, Agwanda BR, Al Kubrusli R, Alkhovsky, SV, Amarasinghe GK, Avšič-Županc T, Ayllón MA, Bahl J, Balkema-Buschmann A, Ballinger MJ, Basler CF, Bavari S, Beer M, Bejerman N, Bennett AJ, Bente DA, Bergeron É, Bird BH, Blair CD, Blasdell KR, Blystad DR, Bojko J, Borth WB, Bradfute S, Breyta R, Briese T, Brown PA, Brown JK et al. 2021. Taxonomic update of Phylum Negarnaviricota (Riboviria: Orthornavirae), including the largest orders, Bunyavirales and Mononegavirales. Arch. Virol. Aug 31. doi: 10.1007/s00705-021-05143-6. Epub PMID: 34463877.
• Brown, J. K., Haq, Q. M., Sohrab, S. S., & Al-Harrasi, A. (2021). Association of tomato yellow leaf curl virus - Oman strain with the leaf curl and yellow mosaic symptoms on papaya and wild poinsettia in Oman.. Can J Phytopathol, 2021, 1-8. doi:10.1080/07060661.2021.1995500
• Brown, J. K., Keith, C. V., Ramos-Sobrinho, R., & Marelli, J. P. (2021). Construction of an infectious clone of the badnavirus Cacao swollen shoot Ghana M virus and infectivity by gene gun- and Agrobacterium-mediated inoculation.. Front Agron, 3, 774863. doi:10.3389/fagro.2021.774863
• Brown, J. K., Kouakou, K., Bolou, B. A., Keith, C. V., Dilby, L., Kouame, C., AKA, A. R., Marelli, J. P., & Ramos-Sobrinho, R. (2021). Molecular identification of Cacao swollen shoot badnavirus species by amplification with four PCR primer pairs, and evidence that Cacao swollen shoot Togo B virus-like isolates are highly prevalent in Côte d’Ivoire. Eur. J. Plant Pathol, 159, 941-947. doi:doi10.1007/s00705-021-05063-5
• Brown, J. K., Li, Z., She, X., Yu, L., Lv, L., & He, Z. (2021). Complete genome sequence of a previously undescribed monopartite begomovirus and betasatellite infecting Malvastrum coromandelianum in Cambodia.. Arch Virol, 166, 1789-1793.
• Brown, J. K., Paredes-Montero, J. R., & Haq, I. Q. (2021). Phylogeographic and SNPs analyses of Bemisia tabaci B mitotype populations reveal only two of eight haplotypes are invasive.. Biology, 10, 1048. doi:https://doi.org/10.3390/biology10101048
• Brown, J. K., Park, S. H., & Steichen, S. A. (2021). Single nucleotide polymorphism-mismatch primer development for rapid molecular identification of selected microalgal species. J Appl Phycol, 33, 1685-1694. doi:https://doi.org/10.1007/s10811-021-02409-z
• Brown, J. K., Ramos-Sobrinho, R., Adegbola, R. O., Lawrence, K., Schrimsher, D. W., Isakeit, T., & Alabi, O. J. (2021). Cotton leafroll dwarf virus US genomes comprise divergent subpopulations and harbor extensive variability. Viruses, 13, 2230. doi:10.3390/v13112230.
• Brown, J. K., Ramos-Sobrinho, R., Mayra, M. M., Ferro, M. M., Nagata, N., Puig, A. S., Keith, C. V., Gutierrez, O. A., & Marelli, J. P. (2021). Complete genome sequences of three newly discovered cacao mild mosaic virus isolates from Theobroma cacao L. in Brazil and Puerto Rico and evidence for recombination. Arch Virol, 166(7), 2027. doi:10.1007/s00705-021-05063-5
• Brown, J. K., Shah, S. H., Paredes-Montero, J. R., Malik, A., & Qazi, J. (2021). Distribution of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) mitotypes in commercial cotton fields in the Punjab province of Pakistan. Fl Entomol, 103(1), 41-47. doi:10.1653/024.103.0407.
• Brown, J. K., Shahid, M. S., & Briddon, R. W. (2021). Interaction of a Tomato leaf curl New Delhi virus with a betasatellite enhances symptom severity in field-infected tomato plants. Trop Pl Pathol, 46, 169-174. doi:10.1007/s40858-020-00414-0
• Brown, J. K., Shaurub, M. S., Paredes-Montero, J. R., Zein, H. S., & Mohamed, A. A. (2021). Metabolic resistance to organophosphate insecticides in natural populations of the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) in Egypt and molecular identification of mitotypes. Phytoparasitica, 49, 443-457. doi:10.1007/s12600-020-00858-9
• Cicero, J. M., & Brown, J. K. (2021). A STATIONARY TWEEZER PLATFORM FOR HIGH THROUGHPUT DISSECTIONS OF MINUTE ARTHROPODS AND EXTIRPATION OF THEIR MINUTE ORGANS. MethodsX, 8. doi:10.1016/j.mex.2021.101317
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  ABSTRACT A home-made platform satisfied the need for fast, efficient dissection of minute arthropods and extirpation of their key organs, such as salivary glands and midguts, involved in agricultural disease transmission pathways. With its implementation, ∼200 organs could be extirpated per 8hr workday while the subjects are submerged in protein or transcript protectant. A vacuum wand is used to capture insects and position them in the field of view. Two stationary tweezers are positioned on an adjustable scaffold that spans the microscope stage transversely such that their tips, and the insects they immobilize, can be submerged in select dissection media. High tensile strength fishlines are attached to the stationary tweezers for opening and closing with the 5th fingers while hand-held dissection tweezers load insects from the wand to their tines, then extirpate the target organs. Organs are lifted out with glass splints or plastic toothpicks into a final tube of select preservation media for freezing at session end. • Constructed from common retail materials • Adjustable design fits many microscopes • Can also be used in a wide variety of applications, including materials science
• Keith, C. V., Ramos-Sobrinho, R., Marelli, J. P., & Brown, J. K. (2021). Construction of an Infectious Clone of the Badnavirus Cacao Swollen Shoot Ghana M Virus and Infectivity by Gene Gun- and Agrobacterium-Mediated Inoculation. Frontiers in Agronomy, 3(Issue). doi:10.3389/fagro.2021.774863
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  Cacao swollen shoot disease (CSSD) is a damaging disease of Theobroma cacao L. associated with infection by a group of poorly characterized badnaviral species. To establish causality and characterize the symptomatology associated with infection by the badnavirus cacao swollen shoot Ghana M virus (CSSGMV), an infectious clone (1.3-mer) was constructed and used to inoculated cacao “Amelonado” seedlings by biolistic inoculation (BI; n = 18) and agroinoculation (AI; n = 15). Newly expanded leaves of BI (10/18) and AI (12/15) plants developed foliar mosaic and curling symptoms 30-days post inoculation (dpi), with chlorotic mottling and necrotic crinkling being evident by 90 dpi. By 120 dpi, three of 15 AI plants exhibited characteristic stem-swelling. Viral infection was verified by PCR-amplification and sequencing of a 1068 bp fragment of the CSSGMV ORF3 from newly expanding leaves 60 dpi. The PCR results indicated that 14 of 18 and 15 of 15 BI and AI plants, respectively, were systemically infected. The complete CSSGMV genome sequence was determined, by Illumina sequencing, from representative AI and BI plants and shared >99.5% pairwise nucleotide identity with CSSGMV-Nig9 (GenBank Accession No. MH785299). Based on the development of characteristic CSSD symptoms and recovery of partial and complete genome sequences of CSSGMV-Nig9 from systemically infected cacao plants, Koch's postulates have been fulfilled.
• Paredes-Montero, J. R., Imranul Haq, Q. M., Mohamed, A. A., & Brown, J. K. (2021). Phylogeographic and snps analyses of bemisia tabaci b mitotype populations reveal only two of eight haplotypes are invasive. Biology, 10(Issue 10). doi:10.3390/biology10101048
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  The Bemisia tabaci cryptic species contains 39 known mitotypes of which the B and Q are best recognized for having established outside their extant endemic range. In the 1980s, previously uncharacterized haplotype(s) of the B mitotype rapidly established in tropical and subtropical locales distant from their presumed center of origin, leading to displacement of several native mitotypes and extreme damage to crops and other vegetation particularly in irrigated agroecosystems. To trace the natural and evolutionary history of the invasive B haplotypes, a phylo-biogeographic study was undertaken. Patterns of single nucleotide polymorphisms (SNPs) and signatures potentially indicative of geographic isolation were investigated using a globally representative mitochondrial cytochrome oxidase I gene (mtCOI) sequence database. Eight haplotype groups within the North Africa-Middle East (NAFME) region were differentiated, NAFME 1–8. The NAFME 1–3 haplotypes were members of the same population that is associated with warm desert climate niches of the Arabian Peninsula and east coastal Africa-Ethiopia. The NAFME 4 and 5 haplotypes are endemic to warm and cold semi-arid niches delimited by the Irano-Turanian floristic region, itself harboring extensive biodiversity. Haplotypes 6 and 7 co-occurred in the Middle East along eastern Mediterranean Sea landmasses, while NAFME 8 was found to be endemic to Cyprus, Turkey, and desert micro-niches throughout Egypt and Israel. Contrary to claims that collectively, the B mitotype is invasive, NAFME 6 and 8 are the only haplotypes to have established in.
• Ramos-Sobrinho, R., Adegbola, R. O., Lawrence, K., Schrimsher, D. W., Isakeit, T., Alabi, O. J., & Brown, J. K. (2021). Cotton leafroll dwarf virus us genomes comprise divergent subpopulations and harbor extensive variability. Viruses, 13(Issue 11). doi:10.3390/v13112230
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  Cotton leafroll dwarf virus (CLRDV) was first reported in the United States (US) in 2017 from cotton plants in Alabama (AL) and has become widespread in cotton-growing states of the southern US. To investigate the genomic variability among CLRDV isolates in the US, complete genomes of the virus were obtained from infected cotton plants displaying mild to severe symptoms from AL, Florida, and Texas. Eight CLRDV genomes were determined, ranging in size from 5865 to 5867 bp, and shared highest nucleotide identity with other CLRDV isolates in the US, at 95.9–98.7%. Open reading frame (ORF) 0, encoding the P0 silencing suppressor, was the most variable gene, sharing 88.5–99.6% and 81.2–89.3% amino acid similarity with CLRDV isolates reported in cotton growing states in the US and in Argentina and Brazil in South America, respectively. Based on Bayesian analysis, the complete CLRDV genomes from cotton in the US formed a monophyletic group comprising three relatively divergent sister clades, whereas CLRDV genotypes from South America clustered as closely related sister-groups, separate from US isolates, patterns reminiscent of phylogeographical structuring. The CLRDV isolates exhibited a complex pattern of recombination, with most breakpoints evident in ORFs 2 and 3, and ORF5. Despite extensive nucleotide diversity among all available CLRDV genomes, purifying selection (dN/dS < 1) was implicated as the primary selective force acting on viral protein evolution.
• Ramos-Sobrinho, R., Ferro, M. M., Nagata, T., Puig, A. S., Keith, C. V., Britto, D. S., Gutierrez, O. A., Marelli, J. P., & Brown, J. K. (2021). Complete genome sequences of three newly discovered cacao mild mosaic virus isolates from Theobroma cacao L. in Brazil and Puerto Rico and evidence for recombination. Archives of Virology, 166(Issue 7). doi:10.1007/s00705-021-05063-5
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  To analyze the DNA virome associated with cacao (Theobroma cacao L.) trees showing virus-like symptoms in Brazil (BR) and Puerto Rico (PR) during 2018-2019, total DNA was isolated from symptomatic leaves and subjected to high-throughput Illumina sequencing. The assembled complete badnaviral genome sequences were verified by PCR amplification, cloning, and DNA sequencing. Based on pairwise distances and phylogenetic analysis, three badnaviral genomes were identified, and these viruses were found to be isolates of the previously described cacao mild mosaic virus (CaMMV). The three genomes were 7,520, 7,524, and 7,514 bp in size for the isolates CaMMV-BR321, CaMMV-BR322, and CaMMV-PR3, respectively. Each genome contained four predicted open reading frames: ORFs 1-3 and ORFY. The CaMMV-PR3 isolate was identified as a probable recombinant, with a CaMMV-BR-like virus as the major parent.
• Steichen, S. A., Park, S. H., Steichen, S. A., Park, S., & Brown, J. K. (2021). Single nucleotide polymorphism-mismatch primer development for rapid molecular identification of selected microalgal species. Journal of Applied Phycology, 1-10. doi:10.1007/s10811-021-02409-z
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  Microalgae have been a great source for food, cosmetic, pharmacological, and biofuel production. The adoption of effective diagnostic assays for monitoring all stages of algal cultivation has become essential. In addition to microscopy identification, molecular assays can aid greatly in the identification and monitoring of algal species of interest. In this study the 18S ribosomal RNA (rRNA) sequences of 12 microalgal species and/or strains were used to design algal identification primers. Sequence alignment revealed five highly variable regions and multiple unique single nucleotide polymorphisms (SNPs). To design target algae specific primers, a SNP identified as unique to each microalgal species was incorporated into the 3’-terminus of forward and reverse primer pairs, respectively. To further enhance primer specificity, transverse mutation was introduced into each primer at the third base upstream of the respective SNP. The SNP-mismatch primer pairs yield size-specific amplicons, enabling the rapid molecular detection of 12 microalgae by circumventing cloning and sequencing. To verify the primer specificity, two SNP-mismatch primer pairs designed for Chlorella sorokiniana DOE1412 and wildtype species of Scenedesmus were tested in the outdoor reactor run inoculated with C. sorokiniana DOE1412. The primer pairs were able to identify C. sorokiniana DOE1412 as well as the environmental invader Scenedesmus sp. Furthermore, the “relative concentration” of two microalgae was accessed throughout the entire cultivation run. The use of SNPs primers designed in this study offers a cost-effective, easy to use alternative for routine monitoring of microalgal cultures in laboratories, in scale-ups, and in cultivation reactors, independent of the production platform.
• Tang, Y., Li, Z., She, X., Yu, L., Lan, G., Lv, L., Brown, J. K., & He, Z. (2021). Complete genome sequence of a previously undescribed monopartite begomovirus and betasatellite infecting Malvastrum coromandelianum in Cambodia. Archives of Virology, 166(Issue 6). doi:10.1007/s00705-021-05016-y
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  A previously undescribed monopartite begomovirus was identified in Kampot province, Cambodia, in Malvastrum coromandelianum plants exhibiting yellow vein symptoms characteristic of begomovirus infections. The apparently full-length viral component was cloned and sequenced following enrichment of circular DNA by rolling-circle amplification and restriction enzyme digestion. The genome of the virus was 2737 nucleotides in length (KP188831) and exhibited an organization like that of other monopartite begomoviruses, sharing the highest nucleotide sequence similarity (87.7% identity) with ageratum yellow vein virus (AM940137). A satellite molecule was amplified from total DNA by PCR amplification, using the betasatellite-specific primer pair β01/β02. The satellite molecule (1346 nt, KP188832) had structural characteristics like those of other betasatellites associated with begomoviruses and shared the highest nucleotide sequence similarity (84.8% identity) with malvastrum yellow vein betasatellite (MN205547). According to the criteria established for species demarcation for classification of begomoviruses (family Geminiviridae) and betasatellites (family Tolecusatellitidae), respectively, the virus isolate from M. coromandelianum in Cambodia is a previously undescribed novel monopartite begomovirus, for which the name “malvastrum yellow vein Cambodia virus” (MaYVCV) is proposed, and the betasatellite is a previously undescribed novel betasatellite, for which the name “malvastrum yellow vein Cambodia betasatellite” (MaYVKHB) is proposed.
• Alabi, O. J., Isakeit, T., Vaughn, R., Stelly, D., Conner, K. N., Gaytán, B. C., Villegas, C., Hitzelberger, C., De Santiago, L., Monclova-Santana, C., & Brown, J. K. (2020). First report of Cotton leafroll dwarf virus Infecting Upland Cotton (Gossypium hirsutum) in Texas. Plant Disease, 104(Issue 3). doi:10.1094/pdis-09-19-2008-pdn
• Andreason, S. A., Arif, M., Brown, J. K., Ochoa-corona, F. M., & Wayadande, A. (2020). Exploring the Use of High-Resolution Melting Analysis and Helicase-Dependent Amplification for Discrimination of Bemisia tabaci (Hemiptera: Aleyrodidae) Cryptic Species and Trialeurodes vaporariorum.. Journal of economic entomology, 113(5), 2511-2520. doi:10.1093/jee/toaa180
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  The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera; Aleyrodidae), and greenhouse whitefly, Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae), are highly problematic plant pests and virus vectors with worldwide distributions. Identification of whitefly species is typically accomplished by observation of distinct morphological characters; however, because of morphological inconsistency and indistinguishability, the discrimination of B. tabaci species variants is dependent on molecular techniques based on genetic differences. New assays were designed for the detection of B. tabaci A, B, and Q mitotype groups, and T. vaporariorum. Specific primer sets were designed for amplification of the mitochondrial cytochrome c oxidase I gene of the four targets to perform in end-point PCR, real-time PCR coupled to high-resolution melting analysis (HRM), and the isothermal helicase-dependent amplification (HDA). Primer specificities were validated using end-point PCR, then tested in HRM and HDA. Bemisia tabaci A, B, and Q mitotypes, and T. vaporariorum-targeted primer sets discriminately amplified specimens of different populations within their target whitefly group. These tests provide three novel discrimination assays for the high-consequence, exotic B. tabaci B and Q groups, along with the native B. tabaci A group and T. vaporariorum.
• Avelar, S., Brown, J. K., Conner, K., Lawrence, K. S., Nichols, R. L., & Ramos-sobrinho, R. (2020). Characterization of the Complete Genome and P0 Protein for a Previously Unreported Genotype of Cotton Leafroll Dwarf Virus, an Introduced Polerovirus in the United States.. Plant disease, 104(3), 780-786. doi:10.1094/pdis-06-19-1316-re
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  Virus-like disease symptoms consisting of leaf cupping, shortened internodes, and overall stunting were observed in commercial cotton fields in Alabama in 2017 to 2018. To determine the complete genome sequence of the suspected causal polerovirus, symptomatic leaf samples were collected in Macon County, Alabama, and subjected to Illumina RNA sequencing. Based on BLASTn analysis, the Illumina contig of 5,771 nt shared the highest nucleotide identity (approximately 95%) with members of the species Cotton leafroll dwarf virus (CLRDV) (genus Polerovirus; family Luteoviridae) from Argentina and Brazil. The full-length viral genome sequence was verified by reverse transcription (RT)-PCR amplification, cloning, and Sanger sequencing. The complete CLRDV genome of 5,865 nt in length shared 94.8 to 95.2% nucleotide identity with six previously reported CLRDV isolates. The genome of the CLRDV isolate amplified from Alabama samples (CLRDV-AL) has seven predicted open reading frames (ORFs). Viral proteins 1 to 5 (P1 to P5) shared 91.9 to 99.5% amino acid identity with the six CLRDV isolates from Argentina and Brazil. However, P0, the suppressor of host gene silencing, shared 82.4 to 88.5% pairwise amino acid identity with the latter CLRDV isolates. Phylogenetic analysis of the seven full-length CLRDV genomes resolved three sister clades: CLRDV-AL, CLRDV-typical, and CLRDV-atypical, respectively. Three recombination events were detected by the recombination detection program among the seven CLRDV isolates with breakpoints occurring along the genome. Pairwise nucleotide identity comparisons of ORF0 sequences for the three CLRDV-AL field isolates indicated that they were >99% identical, suggesting that this previously unknown CLRDV genotype represents a single introduction to Alabama.
• Avelar, S., Ramos-Sobrinho, R., Conner, K., Nichols, R., Lawrence, K., & Brown, J. (2020). Characterization of the complete genome and P0 protein for a previously unreported genotype of cotton leafroll dwarf virus, an introduced polerovirus in the United States. Plant Disease, 104(3), 780-786. doi:10.1094/PDIS-06-19-1316-RE
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  Virus-like disease symptoms consisting of leaf cupping, shortened internodes, and overall stunting were observed in commercial cotton fields in Alabama in 2017 to 2018. To determine the complete genome sequence of the suspected causal polerovirus, symptomatic leaf samples were collected in Macon County, Alabama, and subjected to Illumina RNA sequencing. Based on BLASTn analysis, the Illumina contig of 5,771 nt shared the highest nucleotide identity (approximately 95%) with members of the species Cotton leafroll dwarf virus (CLRDV) (genus Polerovirus; family Luteoviridae) from Argentina and Brazil. The full-length viral genome sequence was verified by reverse transcription (RT)-PCR amplification, cloning, and Sanger sequencing. The complete CLRDV genome of 5,865 nt in length shared 94.8 to 95.2% nucleotide identity with six previously reported CLRDV isolates. The genome of the CLRDV isolate amplified from Alabama samples (CLRDV-AL) has seven predicted open reading frames (ORFs). Viral proteins 1 to 5 (P1 to P5) shared 91.9 to 99.5% amino acid identity with the six CLRDV isolates from Argentina and Brazil. However, P0, the suppressor of host gene silencing, shared 82.4 to 88.5% pairwise amino acid identity with the latter CLRDV isolates. Phylogenetic analysis of the seven full-length CLRDV genomes resolved three sister clades: CLRDV-AL, CLRDV-typical, and CLRDV-atypical, respectively. Three recombination events were detected by the recombination detection program among the seven CLRDV isolates with breakpoints occurring along the genome. Pairwise nucleotide identity comparisons of ORF0 sequences for the three CLRDV-AL field isolates indicated that they were >99% identical, suggesting that this previously unknown CLRDV genotype represents a single introduction to Alabama.
• Brown, J. K. (2020). First report of Cotton leafroll dwarf virus infecting upland cotton (Gossypium hirsutum L.) in Texas.. Plant Disease [First Report] on-line November 2019. doi:doi.org/10.1094/PDIS-09-19-2008-PDN
• Brown, J. K., Andreason, S. A., Arif, M., Ochoa-Corona, F., & Wayandande, A. (2020). Discrimination of Bemisia tabaci (Hemiptera: Aleyrodidae) species variants and Trialeurodes vaporariorum using real-time melting curve analysis and helicase dependent amplification.. J Econ Entomol, 113(5), 2511. doi:https://doi.org/10.1093
• Brown, J. K., Fondong, V. N., & Leke, W. N. (2020). First Report of Chayote Yellow Mosaic Virus (ChaYMV) and Its Associated Betasatellite Infecting Papaya (Carica papaya) in Cameroon. Plant Disease, 104(5), 1566-1566. doi:10.1094/pdis-11-19-2293-pdn
• Brown, J. K., Leke, W. N., Kvarnheden, A., & Avelar, S. (2020). Molecular characterization of two previously undescribed begomovirus-associated alphasatellite molecules infecting malvaceous species in Cameroon.. Arch Virol, 165(3), 1-5.
• Brown, J. K., Mondal, M., & Flynt, A. (2020). Exploiting somatic piRNAs in the whitefly, Bemisia tabaci enables a new mode of gene silencing through synthetic RNA feeding. Life Sciences Alliance, 3(10), 1-13. doi:10.26508/lsa.202000731
• Brown, J. K., Paredes Montero, J. R., Zia-Ur-Rehman, M., Hameed, U., Herrmann, H. W., Rasool, G., & Haider, M. S. (2020). Genetic variability, community structure, and horizontal transfer of Arsenophonus OTUs among three Asia II-Bemisia tabaci mitotypes in Pakistan. Ecol Evol, 10(6), 2928-2943. doi:https ://doi.org/10.1002/ece3.6107
• Brown, J. K., Paredes-Montero, J. R., Ibarra, M. A., Arias, M., & Paralta, E. (2020). Phylo-biogeographical distribution of whitefly Bemisia tabaci mitotypes in Ecuador. Ecosphere, 11(6). doi:e03154. 10.1002/ ecs2.3154
• Brown, J. K., Ramos-Sobrinho, R., Chingandu, N., Gutierrez, O., & Marelli, J. P. (2020). A complex of badnavirus species infecting cacao reveals mixed infections, extensive genomic variability, and interspecific recombination. Viruses, 12, 443. doi:10.3390/v12040443
• Brown, J. K., Roberts, A., Boeckman, C. J., Mühl, M., & Romeis, J. (2020). Sublethal endpoints in non-target organism testing for insect-active GE crops. Frontiers Bioeng Biotechnol, 8, 556. doi:10.3389/fbioe.2020.00556
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  Roberts, A., Boeckman, C.J., Mühl, M., Romeis, J., Teem, J.L., Hercos, Valicente, F., Brown, J.K., Edwards, M.G., Levine, S.L., Melnick, R.L., Rodrigues, T.B., Vélez, A.M., Zhou, X. and Hellmich, R.L.
• Gao, S., Steichen, S., Brown, J. K., & Waller, P. M. (2020). Association between algal productivity and phycosphere composition in an outdoor Chlorella sorokiniana reactor based on multiple longitudinal analyses.. Microbial biotechnology, 13(5), 1546-1561. doi:10.1111/1751-7915.13591
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  Microalgae as a biofuel source are of great interest. Bacterial phycosphere inhabitants of algal cultures are hypothesized to contribute to productivity. In this study, the bacterial composition of the Chlorella sorokiniana phycosphere was determined over several production cycles in different growing seasons by 16S rRNA gene sequencing and identification. The diversity of the phycosphere increased with time during each individual reactor run, based on Faith’s phylogenetic diversity metric versus days post‐inoculation (R = 0.66, P < 0.001). During summer months, Vampirovibrio chlorellavorus, an obligate predatory bacterium, was prevalent. Bacterial sequences assigned to the Rhizobiales, Betaproteobacteriales and Chitinophagales were positively associated with algal biomass productivity. Applications of the general biocide, benzalkonium chloride, to a subset of experiments intended to abate V. chlorellavorus appeared to temporarily suppress phycosphere bacterial growth, however, there was no relationship between those bacterial taxa suppressed by benzalkonium chloride and their association with algal productivity, based on multinomial model correlations. Algal health was approximated using a model‐based metric, or the ‘Health Index’ that indicated a robust, positive relationship between C. sorokiniana fitness and presence of members belonging to the Burholderiaceae and Allorhizobium–Neorhizobium–Pararhizobium–Rhizobium clade. Bacterial community composition was linked to the efficiency of microalgal biomass production and algal health.
• Leke, W. N., Kvarnheden, A., Avelar, S., & Brown, J. K. (2020). Molecular characterization of two previously undescribed begomovirus-associated alphasatellite molecules infecting malvaceous species in Cameroon. Archives of Virology, 165(Issue 3). doi:10.1007/s00705-020-04523-8
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  Two begomovirus-associated alphasatellites were isolated from okra and a malvastrum plant (Malvaceae) in Cameroon. The complete nucleotide sequences of the okra- and malvastrum-infecting alphasatellites were 1375 and 1416–1418 nucleotides, respectively, and both exhibited features characteristic of other alphasatellites. Based on pairwise sequence comparisons, these previously undescribed alphasatellites are members of distinct species in the genera Colecusatellite and Gosmusatellite and have been tentatively named “pepper yellow vein Mali alphasatellite” and “cotton leaf curl Gezira alphasatellite3”, respectively. Taken together with previous studies, alphasatellites endemic to Cameroon appear to be more diverse and infect plants of many more species and families than currently recognized.
• Mondal, M., Brown, J. K., & Flynt, A. (2020). Exploiting somatic piRNAs in Bemisia tabaci enables novel gene silencing through RNA feeding. Life Science Alliance, 3(Issue 10). doi:10.26508/lsa.202000731
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  RNAi promises to reshape pest control by being nontoxic, biodegradable, and species specific. However, due to the plastic nature of RNAi, there is a significant variability in responses. In this study, we investigate small RNA pathways and processing of ingested RNAi trigger molecules in a hemipteran plant pest, the whitefly Bemisia tabaci. Unlike Drosophila, where the paradigm for insect RNAi technology was established, whitefly has abundant somatic piwi-associated RNAs (piRNAs). Long regarded as germline restricted, piRNAs are common in the soma of many invertebrates. We sought to exploit this for a novel gene silencing approach. The main principle of piRNA biogenesis is the recruitment of target RNA fragments into the pathway. As such, we designed synthetic RNAs to possess complementarity to the loci we annotated. Following feeding of these exogenous piRNA triggers knockdown as effective as conventional siRNA-only approaches was observed. These results demonstrate a new approach for RNAi technology that could be applicable to dsRNA-recalcitrant pest species and could be fundamental to realizing insecticidal RNAi against pests.
• Paredes-Montero, J. R., Zia-Ur-Rehman, M., Hameed, U., Haider, M. S., Herrmann, H. W., & Brown, J. K. (2020). Genetic variability, community structure, and horizontal transfer of endosymbionts among three Asia II-Bemisia tabaci mitotypes in Pakistan. Ecology and Evolution, 10(Issue 6). doi:10.1002/ece3.6107
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  Endosymbionts associated with the whitefly Bemisia tabaci cryptic species are known to contribute to host fitness and environmental adaptation. The genetic diversity and population complexity were investigated for endosymbiont communities of B. tabaci occupying different micro-environments in Pakistan. Mitotypes of B. tabaci were identified by comparative sequence analysis of the mitochondria cytochrome oxidase I (mtCOI) gene sequence. Whitefly mitotypes belonged to the Asia II-1, -5, and -7 mitotypes of the Asia II major clade. The whitefly–endosymbiont communities were characterized based on 16S ribosomal RNA operational taxonomic unit (OTU) assignments, resulting in 43 OTUs. Most of the OTUs occurred in the Asia II-1 and II-7 mitotypes (r2 =.9, p
• Paredes-montero, J. R., Peralta, E. L., Paredes-montero, J. R., Ibarra, M. A., Brown, J. K., & Arias-zambrano, M. (2020). Phylo-biogeographical distribution of whitefly Bemisia tabaci (Insecta: Aleyrodidae) mitotypes in Ecuador. Ecosphere, 11(6). doi:10.1002/ecs2.3154
• Puig, A. S., Ramos-Sobrinho, R., Keith, C., Kitchen, N., Gutierrez, O., Goenaga, R., & Brown, J. K. (2020). First report of cacao mild mosaic virus associated with symptomatic commercial cacao (theobroma cacao) trees in puerto rico. Plant Disease, 104(Issue 11). doi:10.1094/pdis-04-20-0745-pdn
• Ramos-Sobrinho, R., Chingandu, N., Gutierrez, O. A., Marelli, J. P., & Brown, J. K. (2020). A complex of badnavirus species infecting cacao reveals mixed infections, extensive genomic variability, and interspecific recombination. Viruses, 12(Issue 4). doi:10.3390/v12040443
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  The incidence of cacao swollen shoot disease (CSSD) in cacao (Theobroma cacao L.) has increased in West Africa since ~2000. To investigate the genomic and species diversity of the CSSD-badnaviruses infecting cacao in Côte d’Ivoire and Ghana, symptomatic leaves were subjected to high-throughput sequencing. Among the 30 newly determined genomes, three badnaviruses were identified, Cacao swollen shoot Togo B virus (CSSTBV), Cacao swollen shoot CD virus, and Cacao swollen shoot CE virus (CSSCEV). The phylogenetic trees reconstructed for the reverse transcriptase (RT) and ribonuclease H (RNase H) sequences were incongruent with the complete viral genomes, which had the most robust statistical support. Recombination seems to be involved in the CSSD-badnavirus diversification. The genomic diversity varied among different CSSD-badnaviruses, with CSSTBV showing the lowest nucleotide diversity (π = 0.06236), and CSSCEV exhibiting the greatest variability (π = 0.21911). Evidence of strong purifying selection was found in the coding regions of the CSSTBV isolates.
• Shah, S. H., Paredes-Montero, J. R., Malik, A. H., Brown, J. K., & Qazi, J. (2020). Distribution of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) mitotypes in commercial cotton fields in the Punjab province of Pakistan. Florida Entomologist, 103(Issue 1). doi:10.1653/024.103.0407
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  The Bemisia tabaci (Gennadius) (Hemiptera: Aleyroridae) sibling species group is comprised of genetic variants defined by biological differences or a fragment of mitochondrial cytochrome oxidase I gene sequence (mitotype) that allows for phylogeographic affiliation. Some mitotypes may cause damage to crop plants by feeding and transmission of plant viruses. In Pakistan, cotton-vegetable agroecosystems are vulnerable to whitefly-transmitted virus (genus Begomovirus; family Geminiviridae) infection. The identity and distribution of the whitefly B. tabaci mitotypes associated with the cotton crop were studied in 8 districts in the Punjab Province from 2014 to 2016. Phylogenetic analysis of the 3?-fragment of the mitochondrial cytochrome oxidase I gene indicated the predominant haplotypes belonged to the Asia II-1 mitotype, with pairwise distances ranging from 0.15 to 3.2%. Pairwise distances showed that B. tabaci haplotype diversity varied by district, with the Khanewal harboring the highest divergence at 1.37%, compared to the lowest at 0.50% in the Dera Ghazi Khan district. The median-joining network analysis showed genetic expansion, or a 'recovery' trend, following the declining genetic diversity that occurred during the late 1990s to the early 2000s. The Asia II-1 mitotype group was the predominant whitefly vector species in Punjab Province. The haplotype network provides documentation of continued genetic expansion among the B. tabaci populations in the Punjab, which is consistent with previously reported trends among whiteflies sampled in the same or nearby districts from 2012 to 2014. Genetic expansion varied among districts and could be explained by factors unique to each district, i.e., management practices that influence B. tabaci mitotype composition, whitefly susceptibility to cotton leaf curl disease complex, and cotton genotype.
• Steichen, S. A., Gao, S., Waller, P., & Brown, J. K. (2020). Association between algal productivity and phycosphere composition in an outdoor Chlorella sorokiniana reactor based on multiple longitudinal analyses. Microbial Biotechnology, 13(Issue 5). doi:10.1111/1751-7915.13591
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  Microalgae as a biofuel source are of great interest. Bacterial phycosphere inhabitants of algal cultures are hypothesized to contribute to productivity. In this study, the bacterial composition of the Chlorella sorokiniana phycosphere was determined over several production cycles in different growing seasons by 16S rRNA gene sequencing and identification. The diversity of the phycosphere increased with time during each individual reactor run, based on Faith’s phylogenetic diversity metric versus days post-inoculation (R = 0.66, P < 0.001). During summer months, Vampirovibrio chlorellavorus, an obligate predatory bacterium, was prevalent. Bacterial sequences assigned to the Rhizobiales, Betaproteobacteriales and Chitinophagales were positively associated with algal biomass productivity. Applications of the general biocide, benzalkonium chloride, to a subset of experiments intended to abate V. chlorellavorus appeared to temporarily suppress phycosphere bacterial growth, however, there was no relationship between those bacterial taxa suppressed by benzalkonium chloride and their association with algal productivity, based on multinomial model correlations. Algal health was approximated using a model-based metric, or the ‘Health Index’ that indicated a robust, positive relationship between C. sorokiniana fitness and presence of members belonging to the Burholderiaceae and Allorhizobium–Neorhizobium–Pararhizobium–Rhizobium clade. Bacterial community composition was linked to the efficiency of microalgal biomass production and algal health.
• Steichen, S. A., Steichen, S. A., Starkenburg, S. R., Hovde, B. T., & Brown, J. K. (2020). Vampirovibrio chlorellavorus draft genome sequence, annotation, and preliminary characterization of pathogenicity determinants. Phycological Research, 68(1), 23-29. doi:10.1111/pre.12392
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  Vampirovibrio chlorellavorus is recognized as a pathogen of commercially‐relevant Chlorella species. Algal infection and total loss of productivity (biomass) often occurs when susceptible algal hosts are cultivated in outdoor open pond systems. The pathogenic life cycle of this bacterium has been inferred from laboratory and field observations, and corroborated in part by the genomic analyses for two Arizona isolates recovered from an open algal reactor. V. chlorellavorus predation has been reported to occur in geographically‐ and environmentally‐diverse conditions. Genomic analyses of these and additional field isolates is expected to reveal new information about the extent of ecological diversity and genes involved in host‐pathogen interactions. The draft genome sequences for two isolates of the predatory V. chlorellavorus (Cyanobacteria; Ca. Melainabacteria) from an outdoor cultivation system located in the Arizona Sonoran Desert were assembled and annotated. The genomes were sequenced and analyzed to identify genes (proteins) with predicted involvement in predation, infection, and cell death of Chlorella host species prioritized for biofuel production at sites identified as highly suitable for algal production in the southwestern USA. Genomic analyses identified several predicted genes encoding secreted proteins that are potentially involved in pathogenicity, and at least three apparently complete sets of virulence (Vir) genes, characteristic of the VirB‐VirD type system encoding the canonical VirB1‐11 and VirD4 proteins, respectively. Additional protein functions were predicted suggesting their involvement in quorum sensing and motility. The genomes of two previously uncharacterized V. chlorellavorus isolates reveal nucleotide and protein level divergence between each other, and a previously sequenced V. chlorellavorus genome. This new knowledge will enhance the fundamental understanding of trans‐kingdom interactions between a unique cosmopolitan cyanobacterial pathogen and its green microalgal host, of broad interest as a source of harvestable biomass for biofuels or bioproducts.
• Zhou, X., Velez, A. M., Valicente, F. H., Teem, J. L., Romeis, J., Rodrigues, T. B., Roberts, A., Muhl, M., Melnick, R. L., Levine, S. L., Hellmich, R. L., Edwards, M. G., Brown, J. K., & Boeckman, C. J. (2020). Sublethal Endpoints in Non-target Organism Testing for Insect-Active GE Crops.. Frontiers in bioengineering and biotechnology, 8, 556. doi:10.3389/fbioe.2020.00556
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  Historically, genetically engineered (GE) plants that have incorporated genes conferring insect protection have primarily used Cry proteins derived from Bacillus thuringiensis (Bt) to achieve their insecticidal phenotype. As a result, regulators have developed a level of familiarity and confidence in reviewing plants incorporating these insecticidal proteins. However, new technologies have been developed that produce GE plants that incorporate pest protection by triggering an RNA interference (RNAi) response or proteins other than Bt Cry proteins. These technologies have new modes of action. Although the overall assessment paradigm for GE plants is robust, there are ongoing discussions about the appropriate tests and measurement endpoints needed to inform non-target arthropod assessment for technologies that have a different mode of action than the Bt Cry proteins. As a result, increasing attention is being paid to the use of sublethal endpoints and their value for environmental risk assessment (ERA). This review focuses on the current status and history of sublethal endpoint use in insect-active GE crops, and evaluates the future use of sublethal endpoints for new and emerging technologies. It builds upon presentations made at the Workshop on Sublethal Endpoints for Non-target Organism Testing for Non-Bt GE Crops (Washington DC, USA, 4-5 March 2019), and the discussions of government, academic and industry scientists convened for the purpose of reviewing the progress and status of sublethal endpoint testing in non-target organisms.
• Attalah, S., Waller, P. M., Steichen, S., Brown, C., Gao, S., Ogden, K. L., & Brown, J. K. (2019). Application of deoxygenation-aeration cycling to control the predatory bacterium Vampirovibrio chlorellavorus in Chlorella sorokiniana cultures. Algal Research, 39. doi:https://doi.org/10.1016/j.algal.2019.101427
• Attalah, S., Waller, P. M., Steichen, S., Brown, C., Gao, S., Ogden, K. L., & Brown, J. K. (2019). Cost minimization of deoxygenation for control of Vampirovibrio chlorellavorus in Chlorella sorokiniana cultures. Algal Research, 42, 1061. doi:https://doi.org/10.1016/j.algal.2019.101615/
• Attalah, S., Waller, P. M., Steichen, S., Gao, S., Brown, J. K., & Ogden, K. L. (2019). Deoxygenation-aeration cycling-driven management of a predatory bacterium Vampirovibrio chlorellavorus in Chlorella sorokiniana algae culture.. Algal Research, 39. doi:https://doi.org/10.1016/j.algal.2019.101427
• Attalah, S., Waller, P., Steichen, S., Brown, C. C., Mehdipour, Y., Ogden, K., & Brown, J. K. (2019). Cost minimization of deoxygenation for control of Vampirovibrio chlorellavorus in Chlorella sorokiniana cultures. Algal Research, 42. doi:10.1016/j.algal.2019.101615
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  Deoxygenation is a strategy for preventing Vampirovibrio chlorellavorus infection of Chlorella sorokiniana cultures. Deoxygenation cost was minimized by sparging with nitrogen gas for only 1 h at the onset of night and relying on naturally-occurring dark-respiration to maintain low oxygen concentrations throughout the night. This technique substantially reduced V. chlorellavorus infection in laboratory co-cultures. The cost of the approach was evaluated in outdoor experiments with one pure water and one pathogen-free C. sorokiniana culture, grown in a 150-L sealed, vented, translucent-polyethylene reactor. Unlike the small laboratory reactors, which were also sealed and vented, the much larger outdoor reactor maintained the dissolved oxygen concentration in the C. sorokiniana culture at near zero concentration throughout the night cycle. This demonstrates that large covered tanks in commercial applications would keep oxygen concentration near zero for the entire night. The total nitrogen sparged, per night, per liter of algal culture, was determined for the 150-L reactor, and used to estimate the cost per m2 for large scale raceways. Onsite nitrogen generators are the most cost-effective method to supply a high flow of nitrogen gas to commercial scale raceways. The cost of deoxygenation treatment ranged from $16/ton AFDW algae for a shallow (2 cm) gravity flow system with 75% harvest prior to deoxygenation to over $1300/ton for a 20 cm depth raceway with plastic tanks.
• Attalah, S., Waller, P., Steichen, S., Gao, S., Brown, C. C., Ogden, K., & Brown, J. K. (2019). Application of deoxygenation-aeration cycling to control the predatory bacterium Vampirovibrio chlorellavorus in Chlorella sorokiniana cultures. Algal Research, 39. doi:10.1016/j.algal.2019.101427
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  A previously untested approach was evaluated to enable management of the predatory bacterium, Vampirovibrio chlorellavorus, a pathogen of Chlorella sorokiniana, in suspension cultures grown in a laboratory test reactor. Because V. chlorellavorus is an obligate aerobic bacterium, whereas C. sorokiniana grows under aerobic and anaerobic conditions, deoxygenation of the culture was expected to be detrimental to the pathogen, but not to the algal host. The effect of deoxygenation on the uninfected (healthy) C. sorokiniana suspension cells, compared to the C. sorokiniana-V. chlorellavorus co-culture, was studied in relation to biomass, dissolved oxygen, ratio of C. sorokiniana to V. chlorellavorus DNA, and visual and light microscopic observations. Preliminary experiments were conducted to test the effects of different deoxygenation-aeration cycling regimes on performance of V. chlorellavorus-free C. sorokiniana cultures. To an aerobic culture, pure nitrogen gas was introduced to create anoxic conditions, followed by the injection of ambient air to re-establish an aerobic environment. Under this repeated cycling regime, C. sorokiniana was shown to tolerate the anoxic conditions for extended timespans that ranged from 2 to 8 h over a 5-day test period. The analogous aerobic-anoxic cycling with the C. sorokiniana-V. chlorellavorus co-cultures resulted in ‘near-normal’ growth cycle and harvestable biomass, whereas the continuously-aerated (aerobic) co-cultures that were grown without the deoxygenation step in the cycle collapsed in 3 days. Visual and light microscopic observations revealed intact C. sorokiniana cells were present in the deoxygenated cultures, compared to the aerobically-grown, brown-colored algal cultures consisting of collapsed cells. Quantitative polymerase chain reaction analysis showed continuous increases in the ratio of V. chlorellavorus (16S rDNA) to C. sorokiniana (18S rDNA) DNA in the aerated co-cultures, with greater increases during dark periods, while the pathogen-to-host DNA ratio in the deoxygenated co-cultures was relatively low and algal cells did not collapse, as would be expected following pathogen attack.
• Bailey, B. A., Barreto, R. W., Brown, J. K., Evans, H. C., Guest, D. I., Junaid, M., Lisboa, D. O., Marelli, J., & Puig, A. S. (2019). Chocolate Under Threat from Old and New Cacao Diseases.. Phytopathology, 109(8), 1331-1343. doi:10.1094/phyto-12-18-0477-rvw
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  Theobroma cacao, the source of chocolate, is affected by destructive diseases wherever it is grown. Some diseases are endemic; however, as cacao was disseminated from the Amazon rain forest to new cultivation sites it encountered new pathogens. Two well-established diseases cause the greatest losses: black pod rot, caused by several species of Phytophthora, and witches' broom of cacao, caused by Moniliophthora perniciosa. Phytophthora megakarya causes the severest damage in the main cacao producing countries in West Africa, while P. palmivora causes significant losses globally. M. perniciosa is related to a sister basidiomycete species, M. roreri which causes frosty pod rot. These Moniliophthora species only occur in South and Central America, where they have significantly limited production since the beginnings of cacao cultivation. The basidiomycete Ceratobasidium theobromae causing vascular-streak dieback occurs only in South-East Asia and remains poorly understood. Cacao swollen shoot disease caused by Cacao swollen shoot virus is rapidly spreading in West Africa. This review presents contemporary research on the biology, taxonomy and genomics of what are often new-encounter pathogens, as well as the management of the diseases they cause.
• Brown, J. K. (2019). Application of deoxygenation-aeration cycling to control a predatory bacterium Vampirovibrio chlorellavorus in Chlorella sorokiniana cultures.. Algal Res., 39, 1427. doi:https://doi.org/10.1016/j.algal.2019.101427
• Brown, J. K. (2019). Characterization of the complete genome and P0 protein for a previously unreported strain of Cotton leafroll dwarf virus, an introduced polerovirus in the USA. Plant Disease, 103(4), 1302-1308. doi:https://doi.org/10.1094/PDIS-06-19-1316-RE
• Brown, J. K. (2019). Demographic expansion of the predominant Bemisia tabaci mitotypes associated with the cotton leaf curl virus pandemic in Pakistan. Ann. Entomol Soc. Am, 112(3), 265-280. doi:https://doi.org/10.1093/aesa/saz002
• Brown, J. K. (2019). First report of Chayote yellow mosaic virus and its associated betasatellite infecting papaya (Carica papaya) in Cameroon. Plant Disease [First Report], 104. doi:doi.org/10.1094/PDIS-11-19-2293-PDN.
• Brown, J. K. (2019). First report of Cotton leaf curl Gezira virus and its associated alphasatellite and betasatellite from disease affected okra plants in the United States.. Plant Disease [First Report], 103(12), 3291. doi:doi.org/10.1094/PDIS-12-18-2197-PDN
• Brown, J. K. (2019). First report of Cotton leafroll dwarf virus associated with cotton blue disease symptoms in Alabama. Plant Disease [First Report], 103, 592. doi:doi.org/10.1094/PDIS-09-18-1550-PDN
• Brown, J. K. (2019). First report of Cotton leafroll dwarf virus infecting cotton in Georgia, USA. Plant Disease [First Report], 203(5), 1094. doi:https://doi.org/10.1094/PDIS-12-18-2197-PDN
• Brown, J. K. (2019). Host-free biofilm culture of “Candidatus Liberibacter asiaticus,” the bacterium associated with Huanglongbing. Biofilm, 1, 1-8. doi:doi.org/10.1016/j.bioflm.2019.100005
• Brown, J. K. (2019). Molecular characterization and detection of Cacao red vein-banding virus, a previously unidentified badnavirus species associated with cacao swollen shoot disease in Nigeria.. Plant Disease, 103(4), 1302-1308. doi:https://doi.org/10.1094/PDIS-09-18-1561-RE; Erratum: Plant Dis. 103(6): 2147. https://apsjournals.apsnet.org/doi/10.1094/PDIS-09-18-1561.1-RE.
• Brown, J. K. (2019). Norovirus and human adenovirus occurrence and diversity in recreational water in a karst aquifer in the Yucatan Peninsula, Mexico. J. Applied Microbiol, 127, 1255-1269. doi:https://doi.org/10.1111/jam.14385
• Brown, J. K. (2019). Phylogenomics of the Bemisia tabaci complex of whiteflies using whole genome sequencing.. Diversity, 11, 151. doi:doi:10.3390/d11090151
• Brown, J. K. (2019). Real-time, quantitative detection of Vampirovibrio chlorellavorus, a bacterial pathogen of Chlorella sorokiniana.. J. Appl. Phycol., 31, 1117–1129. doi:doi.org/10.1007/s10811-018-1659-z
• Brown, J. K. (2019). The infection of bacterial plant pathogen Candidatus Liberibacter solanacearum is associated with altered physiology of its insect host.. Enzyme Microb. Technol., 129, 109358. doi:doi.org/10.1016/j.enzmictec.2019.109358
• Brown, J. K. (2019). Vampirovibrio chlorellavorus draft genome sequence, annotation, and preliminary characterization of pathogenicity determinants. Phycol. Res., 68, 23. doi:doi: 10.1111/pre.12392/
• Brown, J. K. (2020). Molecular characterization of two previously undescribed begomovirus-associated alphasatellite molecules infecting malvaceous species in Cameroon.. Arch. Virol., 165(1), 1-5. doi:doi.org/10.1007/s00705-020-04523-8
• Brown, J. K., Ogden, K. L., Mehdipour, Y., Brown, C., Steichen, S., Waller, P. M., & Attalah, S. (2019). Cost minimization of deoxygenation for control of Vampirovibrio chlorellavorus in Chlorella sorokiniana cultures. Algal Research, 42. doi:https://doi.org/10.1016/j.algal.2019.101615
• Chingandu, N., Dongo, L., Gutierrez, O. A., & Brown, J. K. (2019). The previously unidentified, divergent badnavirus species cacao red vein-banding virus is associated with cacao swollen shoot disease in Nigeria. Plant Disease, 103(Issue 6). doi:10.1094/pdis-09-18-1561-re
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  Cacao swollen shoot disease (CSSD) of Theobroma cacao was reported in Nigeria in 1944; however, no badnaviral genome sequences have been found associated with the symptomatic trees. In 2017, leaf samples (n = 18) were collected from cacao trees from Osun and Oyo, Nigeria showing foliar symptoms that included red vein-banding and shoot swelling, and variable secondary mosaic, mottling, and fern-like pattern symptoms. Abutting primers designed around previously determined 500-bp intergenic region sequences were used for polymerase chain reaction (PCR) amplification. Of the 18 samples, 9 yielded an approximately 7,000-bp, apparently genome-size product. The nine genomes were sequenced and found to encode four open reading frames, and to share 86 to 99% nucleotide identity. Pairwise analysis of the Nigerian genomes with 21 previously reported CSSD badnaviruses, at the complete genome and reverse-transcription ribonuclease H (1,230 bp) sequence levels, indicated 71 to 75 and 72 to 76% nucleotide identity, respectively. Phylogenetic analysis of the nine complete genomes indicated that the closest relatives of the divergent Nigerian isolates were previously described West African CSSD badnaviruses. Based on pairwise comparisons and phylogenetic analyses, the Nigerian CSSD isolates constitute a previously unrecognized Badnavirus sp., herein named Cacao red vein-banding virus (CRVBV). Primers designed based on the CRVBV genome sequences amplified a 1,068-bp fragment from 16 of 18 field samples tested by PCR, suggesting the possible existence of additional CRVBV variants.
• Ha, P. T., He, R., Killiny, N., Brown, J. K., Omsland, A., Gang, D. R., & Beyenal, H. (2019). Host-free biofilm culture of “Candidatus Liberibacter asiaticus,” the bacterium associated with Huanglongbing. Biofilm, 1(Issue). doi:10.1016/j.bioflm.2019.100005
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  Inability to culture the phloem-restricted alpha-proteobacterium “Candidatus Liberibacter asiaticus” (“Ca. L. asiaticus”) or the closely related species (“Candidatus Liberibacter americanus” and “Candidatus Liberibacter africanus”) that are associated with Huanglongbing (HLB) hampers the development of effective long-term control strategies for this devastating disease. Here we report successful establishment and long-term maintenance of host-free “Ca. L. asiaticus” cultures, with the bacterium growing within cultured biofilms derived from infected citrus tissue. The biofilms were grown in a newly designed growth medium under specific conditions. The initial biofilm-based culture has been successfully maintained for over two years and has undergone over a dozen subcultures. Multiple independent cultures have been established and maintained in a biofilm reactor system, opening the door to the development of pure culture of “Ca. L. asiaticus” and the use of genetics-based methods to understand and mitigate the spread of HLB.
• Molki, B., Ha, P. T., Cohen, A. L., Crowder, D. W., Gang, D. R., Omsland, A., Brown, J. K., & Beyenal, H. (2019). The infection of its insect vector by bacterial plant pathogen “Candidatus Liberibacter solanacearum” is associated with altered vector physiology. Enzyme and Microbial Technology, 129(Issue). doi:10.1016/j.enzmictec.2019.109358
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  Many bacterial and viral plant pathogens are transmitted by insect vectors, and pathogen-mediated alterations of plant physiology often influence insect vector behavior and fitness. It remains largely unknown for most plant pathogens whether, and how, they might directly alter the physiology of their insect vectors in ways that promote pathogen transmission. Here we examined whether the presence of “Candidatus Liberibacter solanacearum” (“Ca. L. solanacearum”), an obligate bacterial pathogen of plants and of its psyllid vector alters the physiochemical environment within its insect vector, the potato psyllid (Bactericera cockerelli). Microelectrodes were used to measure the local pH and oxygen tension within the abdomen of “Ca. L. solanacearum”-free psyllids and those infected with “Ca. L. solanacearum”. The hemolymph of infected psyllids had higher pH at 9.09 ± 0.12, compared to “Ca. L. solanacearum”-free psyllids (8.32 ± 0.11) and a lower oxygen tension of 33.99% vs. 67.83%, respectively. The physicochemical conditions inside “Ca. L. solanacearum”-free and –infected psyllids body differed significantly with the infected psyllids having a higher hemolymph pH and lower oxygen tension than “Ca. L. solanacearum”-free psyllids. Notably, the bacterial titer increased under conditions of higher pH and lower oxygen tension values. This suggests that the vector's physiology is altered by the presence of the pathogen, potentially, resulting in a more conducive environment for “Ca. L. solanacearum” survival and subsequent transmission.
• Ogden, K. L., Anderson, D. B., Simpson, S., Voorheis, W. V., Brown, J. K., Huesemann, M. H., Kacira, M., Skaggs, R. L., Skaggs, R., Waller, P. M., Waller, P., & Voorheis, W. V. (2019). RAFT FINAL REPORT Regional Algal Feedstock Testbed. https://www.osti.gov/servlets/purl/1492217/, 84 pages.
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  Final Project Report DOE funded Research
• Paredes-Montero, J. R., Hameed, U., Zia-Ur-Rehman, M., Rasool, G., Haider, M. S., Herrmann, H. W., & Brown, J. K. (2019). Demographic expansion of the predominant Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) mitotypes associated with the cotton leaf curl virus epidemic in Pakistan. Annals of the Entomological Society of America, 112(Issue 3). doi:10.1093/aesa/saz002
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  The association between Bemisia tabaci mitotypes and cotton leaf curl outbreaks in Pakistan was investigated using the mitochondria cytochrome oxidase I gene (COI) as a molecular marker. The 3′-651 base fragment has been used to resolve B. tabaci phylogenies. However, the 5′-618 base fragment was nearly unexplored. Phylogenetic analysis for 829 whiteflies from 11 districts in two provinces of Pakistan, indicated all haplotypes grouped on the Asia II major clade, with Asia II-1 mitotype predominating, at 84%, compared to Asia II-5 and II-7, at ~16%, combined. The 3′- and 5′-fragment tree topologies were similar, while the concatenated topology was unique in some respects. Comparisons of segregating sites within the 3′- and 5′-loci, at third codon positions, 71 and 47, and of transitions to transversions (Ti/Tv) ratio of 2.93 and 5.9, respectively, showed the 3′-locus was most informative, while nucleotide diversity (π) was highest for the 5′-end, indicating both fragments contributed to concatenated tree structure. The extent of haplotype diversity, measured by Tajima’s D, R2, and Fu’s F analyses, revealed significant demographic expansion for Asia II-1 and II-7 mitotypes. The bottleneck that preceded the expansions was evident in the temporal changes in mtCOI polymorphisms beginning in ~1990s, a timeframe known to have coincided with the adoption of a high-yield whitefly-susceptible cultivar in 1988, followed by pesticide overuse. These two cooperating phenomena appear to have exerted selection on the cotton leaf curl disease (CLCuD)-whitefly complex, resulting in the emergence of a resistance-breaking begomovirus as the polyphagous Asia II-1 mitotype underwent a genetic expansion that led to ‘a perfect storm’.
• Rosiles-González, G., Ávila-Torres, G., Moreno-Valenzuela, O. A., Cháidez-Quiroz, C., Hernández-Flores, C. I., Acosta-González, G., Brown, J. K., Betancourt, W. Q., Gerba, C. P., & Hernández-Zepeda, C. (2019). Norovirus and human adenovirus occurrence and diversity in recreational water in a karst aquifer in the Yucatan Peninsula, Mexico. Journal of Applied Microbiology, 127(Issue 4). doi:10.1111/jam.14385
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  Aims: To determine the seasonal occurrence and diversity of norovirus (NoV) and human adenovirus (HAdV) in groundwater from sinkholes, and brackish water used for recreational activities in the karst aquifer of the Yucatan Peninsula, Mexico. Methods and results: Hollow fibre ultrafiltration was used to concentrate viruses and standard plaque assay methods were used to enumerate somatic and F+ specific coliphages as viral indicators. Real-time quantitative polymerase chain reaction assays were used to estimate the number of genome copies for NoV strains GI, and GII, and HAdVs. The predominant NoV genotypes and HAdV serotypes were identified by comparative sequence analysis. Somatic and male F+ specific coliphages were detected at concentrations up to 94 and 60 plaque-forming units per 100 ml respectively. The NoV genogroup I (GI) was associated with 50% of the sampled sites during the rainy season only, at concentrations ranging from 120 to 1600 genome copies per litre (GC l−1). The NoV genogroup II (GII) was detected in 30 and 40% of the sampled sites during the rainy and dry seasons, respectively, at concentrations ranging from 10 to 290 GC l−1. During the rainy and dry seasons, HAdVs were detected in 20% of the sites, at concentrations ranging from 24 to 690 GC l−1. Identification of viral types revealed the presence of NoV GI.2, GII.Pe, GII.P16 and GII.P17, and HAdV F serotypes 40 and 41. Conclusions: These findings demonstrate that NoVs and HAdVs are prevalent as virus contaminants in the karst aquifer, representing potential health risks particularly during the rainy season, in one of the most important areas used for tourism in Mexico. Significance and Impact of the Study: This is one of the few studies conducted in karst aquifers that provide a foundational baseline of the distribution, concentrations and diversity of NoVs and HadVs in these particular environments.
• Steichen, S. A., & Brown, J. K. (2019). Real-time quantitative detection of Vampirovibrio chlorellavorus, an obligate bacterial pathogen of Chlorella sorokiniana. Journal of Applied Phycology, 31(Issue 2). doi:10.1007/s10811-018-1659-z
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  Vampirovibrio chlorellavorus is an obligate, predatory bacterial pathogen of the genus Chlorella. It is recognized as an important pathogen of Chlorella sorokiniana, field isolate DOE 1412, a highly-favored microalga for cultivation in outdoor reactors in the arid USA Southwest for feedstocks used in biofuel production. To determine the V. chlorellavorus titer, based on gene copy number, required to cause infection and mortality of C. sorokiniana in an experimental outdoor reactor, a multiplexed quantitative polymerase chain reaction (qPCR) assay was developed for pathogen detection, based on the 16S and 18S ribosomal RNA gene of V. chlorellavorus and C. sorokiniana, respectively. The assay was further used to establish the optimal effective concentration of benzalkonium chloride required to achieve a below “disease-threshold”-bacterial titer, while minimizing biocidal effects on algal growth and enable economic biomass production. Reactors treated with 2.0 ppm benzalkonium chloride at four-day intervals throughout the cultivation cycle experienced runs of 22 days or longer, compared to 12 days for the untreated control. The qPCR assay was used to estimate disease severity over time using the Area Under the Disease Progress Stairs (AUDPS) metric, indicating a severity rating of 0.016 and 62.308 in biocide-treated and untreated cultures, respectively. The near-real time assay detected as few as 13 copies of V. chlorellavorus, allowing for the recognition of its presence in the reactor just before algal cell density decreased, an indication of pathogen attack, while also informing the timing of biocide applications to minimize DOE 1412 infection such that harvestable biomass could be produced.
• Steichen, S. A., Brown, J. K., Li, X., Ogden, K. L., & Park, S. H. (2019). Association of Vampirovibrio chlorellavorus with decline and death of Chlorella sorokiniana in outdoor reactors. Journal of Applied Phycology, 31(2), 1131-1142. doi:10.1007/s10811-018-1633-9
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  The outdoor ARID raceway was established for optimizing the cultivation of microalgae for biofuel production. During the summers of 2014 and 2015, discoloration was observed in cultures of Chlorella sorokiniana (DOE1412), which shifted from a vibrant green color to yellow, followed by cell clumping, decline in density, and rapid death, resulting in 40–60% reduced biomass production. Total DNA was purified from the raceway samples and subjected to polymerase chain reaction (PCR) amplification using degenerate primers that amplify the 16S rRNA gene of eubacteria. BLASTn analysis of the cloned amplicon sequences revealed the presence of the Gram-negative, predatory bacterium, Vampirovibrio chlorellavorus. Scanning electron microscopic examination showed an abundance of coccoid cells, 0.3–0.6 μm in diameter, some of which were attached to C. sorokiniana cells. PCR amplification indicated the presence of V. chlorellavorus in raceway vessels, water lines, connective tubing, and in early, scaled-up DOE1412 cultures used to inoculate the raceway. Based on PCR detection, the decontamination of the equipment and water line with “Wal-Clean” more effectively eliminated V. chlorellavorus and delayed the onset of attack, compared to the chlorine disinfectant, trichloromelamine (TCM). Total DNA was isolated from soil samples collected monthly from the nearby Rillito River during 2014–2015 and subjected to PCR amplification using primers designed to amplify the 16S rRNA and 18S rRNA gene of V. chlorellavorus and C. sorokiniana, respectively. Results indicated that V. chlorellavorus and Chlorella spp. were present in most of the riverbed samples nearly year round, suggesting a possible naturally occurring reservoir of the predatory bacterium.
• Tabassum, A., Bag, S., Roberts, P., Suassuna, N., Chee, P., Whitaker, J. R., Conner, K. N., Brown, J., Nichols, R. L., & Kemerait, R. C. (2019). First report of cotton leafroll dwarf virus infecting cotton in Georgia, U.S.A.. Plant Disease, 103(Issue 7). doi:10.1094/pdis-12-18-2197-pdn
• Villegas, C., Ramos-Sobrinho, R., Jifon, J. L., Keith, C., Al Rwahnih, M., Sétamou, M., Brown, J. K., & Alabi, O. J. (2019). First report of cotton leaf curl gezira virus and its associated alphasatellite and betasatellite from disease affected Okra plants in the United States. Plant Disease, 103(Issue 12). doi:10.1094/pdis-06-19-1175-pdn
• Zakri, A. M., Idris, A. M., Brown, J. K., & Al-saleh, M. A. (2019). Minimal genomic variability in Merremia mosaic virus isolates endemic in Merremia spp and cultivated tomato in Puerto Rico.. Virusdisease, 30(1), 84-94. doi:10.1007/s13337-017-0412-6
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  Merremia mosaic virus (MerMV), a bipartite begomovirus, was identified for the first time as a pathogen of commercial tomato plantings. Infection of tomato by MerMV caused mild leaf curling and yellow foliar mosaic symptoms. Herein, the MerMV was identified in symptomatic Merremia quinquefolia and M. aegyptia (Convolvulaceae) plants exhibiting bright yellow or yellow-green foliar mosaic symptoms, respectively. The full-length begomoviral components were amplified from total DNA isolated from two wild species of Merremia and commercial tomato plants during 1991-1998. The DNA was subjected to rolling circle amplification, restriction digestion, and DNA sequencing. The resultant 19 and 26 apparently full-length DNA-A and DNA-B components were ~ 2557 and ~ 2492 bases, respectively. The 140-base common region was 97.9% identical between DNA-A and -B components, a predictive evidence for cognate DNA-A and -B components. Although the DNA-A components were highly conserved at 96-100%, the DNA-B components diverged at ~ 89 to 100%, respectively. The overall clonal genomic features strongly suggested that MerMV lineage has been under host-selection for some time, and only recently, has undergone a host-shift, putatively, from wild convolvulaceous species to tomato (Solanaceae). Phylogenetically, MerMV grouped with other bipartite begomoviruses indigenous to the Caribbean region, with MerMV DNA-A components forming three clusters, and the DNA-B components grouped in one clade. Both clades contained only one closet relative, an isolate of MerMV from Venezuela, MerMV-VE. Biolistic inoculation of M. quinquefolia and tomato seedlings with the DNA-A and -B components of PR68 and PR80 resulted in development of symptoms like those observed in naturally-infected species, respectively.
• Zia-ur-rehman, M., Hameed, U., Haider, M. S., Brown, J. K., & Ali, S. A. (2019). Invasion of previously unreported dicot plant hosts by chickpea chlorotic dwarf virus in Pakistan.. Virusdisease, 30(1), 95-100. doi:10.1007/s13337-018-0454-4
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  Members of the genus, Mastrevirus (family, Gemniviridae) transmitted by leafhopper vectors infect monocotyledonous or dicotyledonous plants, and infection of agricultural crops results in reduced yield and quality. During 2012, a study was undertaken in the Punjab and Sindh Provinces in Pakistan to determine the identity of suspect geminiviruses associated with symptomatic cotton and vegetable plants exhibiting foliar enations, leaf curling, mosaic, and stunting reminiscent of geminivirus infection. To determine suspect geminiviral identity, fifteen apparently full-length mastrevirus genome (~ 2600 base pairs) were amplified by rolling-circle amplification, digested, cloned into the plasmid vector, pGEM-3Zf+, and sequenced from cucumber, Gossypium arboreum L., Gossypium hirsutum L., okra and tomato. The mastrevirus full-length genome sequences obtained shared their highest pairwise nucleotide sequence identity, at 97.3-98.6%, with previously reported C and L strains of Chickpea chlorotic dwarf virus (CpCDV) from chickpea and cotton in Pakistan, respectively. However, CpCDV has not been previously identified from cucumber, G. arboreum, okra, or tomato. The association of CpCDV with four previously unreported plant hosts suggests that CpCDV strains C and strain L have a broader than expected host range, and therefore may be found to negatively affect vegetable crops, particularly, when grown in proximity to cotton.
• de Moya, R. S., Brown, J. K., Sweet, A. D., Kimberly, K. K., Paredes-Montero, J. R., Waterhouse, R. M., & Johnson, K. P. (2019). Nuclear orthologs derived from whole genome sequencing indicate cryptic diversity in the Bemisia tabaci (Insecta: Aleyrodidae) complex of whiteflies. Diversity, 11(Issue 9). doi:10.3390/d11090151
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  The Bemisia tabaci complex of whiteflies contains globally important pests thought to contain cryptic species corresponding to geographically structured phylogenetic clades. Although mostly morphologically indistinguishable, differences have been shown to exist among populations in behavior, plant virus vector capacity, ability to hybridize, and DNA sequence divergence. These differences allow for certain populations to become invasive and cause great economic damage in a monoculture setting. Although high mitochondrial DNA divergences have been reported between putative conspecifics of the B. tabaci species complex, there is limited data that exists across the whole genome for this group. Using data from 2184 orthologs obtained from whole genome sequencing (Illumina), a phylogenetic analysis using maximum likelihood and coalescent methodologies was completed on ten individuals of the B. tabaci complex. In addition, automatic barcode gap discovery methods were employed, and results suggest the existence of five species. Although the divergences of the mitochondrial cytochrome oxidase I gene are high among members of this complex, nuclear divergences are much lower in comparison. Single-copy orthologs from whole genome sequencing demonstrate divergent population structures among members of the B. tabaci complex and the sequences provide an important resource to aid in future genomic studies of the group.
• Brown, J. K. (2018). Association of Vampirovibrio chlorellavorus with decline and death of Chlorella sorokiniana in outdoor reactors. J. Appl. Phycol., 1-12. doi:https://doi.org/10.1007/s10811-018-1633-9
• Brown, J. K. (2018). First report of a Tomato yellow leaf curl virus isolate most closely related to a previously reported begomovirus in Iran-associated with symptomatic papaya trees in Oman. J Virol Antivir Res, 7. doi:DOI: 10.4172/2324-8955.1000180
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  Peer-reviewed Short Communication
• Brown, J. K. (2018). First report of an emaravirus associated with witches broom disease and eriophyid mite infestations of the blue palo verde tree in Arizona.. Plant Disease, 201(9), 1863. doi:https://doi.org/10.1094/PDIS-01-18-0124-PDN
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  Peer-reviewed short report (Disease note)
• Brown, J. K. (2018). Harvesting of chlorella sorokiniana by fungal-assisted palletization, and cellulase production: a case of study. J. Biobased Mater. Bioenergy, 12(6), 493-505. doi:doi.org/10.1166/jbmb.2018.1798/
• Brown, J. K. (2018). Harvesting of chlorella sorokiniana by fungal-assisted palletization, and cellulase production: a case of study. J. Biobased Mater. Bioenergy, 12(6), 493-505. doi:https://doi.org/10.1166/jbmb.2018.1798
• Brown, J. K. (2018). Invasion of previously unreported dicot plant hosts by Chickpea chlorotic dwarf virus in Pakistan. Virus Dis.. doi:https://doi.org/10.1007/s13337-018-0454-4
• Brown, J. K. (2018). Low-phosphate-selected Auxenochlorella protothecoides redirects phosphate to essential pathways while producing more biomass. PLoS One, 6(13). doi:https://doi.org/10.1371/journal.pone.0198953
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  Despite the capacity to accumulate ~70% w/w of lipids, commercially produced unicellular green alga A. protothecoides may become compromised due to the high cost of phosphate fertilizers. To address this limitation A. protothecoides was selected for adaptation to conditions of 100× and 5× lower phosphate and peptone, respectively, compared to ‘wild-type media’. The A. protothecoides showed initial signs of adaptation by 45–50 days, and steady state growth at ~100 days. The low phosphate (P)-adapted strain produced up to ~30% greater biomass, while total lipids (~10% w/w) remained about the same, compared to the wild-type strain. Metabolomic analyses indicated that the low P-adapted produced 3.3-fold more saturated palmitic acid (16:0) and 2.2-fold less linolenic acid (18:3), compared to the wild-type strain, resulting in an ~11% increase in caloric value, from 19.5kJ/g for the wild-type strain to 21.6kJ/g for the low P-adapted strain, due to the amounts and composition of certain saturated fatty acids, compared to the wild type strain. Biochemical changes in A. protothecoides adapted to lower phosphate conditions were assessed by comparative RNA-Seq analysis, which yielded 27,279 transcripts. Among them, 2,667 and 15 genes were significantly down- and up-regulated, at >999-fold and >3-fold (adjusted p-value
• Brown, J. K. (2018). Minimal genomic variability between Merremia mosaic virus from endemic Merremia spp. and cultivated tomato in Puerto Rico, is indicative of a recent host shift. Virus Dis.. doi:10.1007/s13337-017-0412-6.
• Brown, J. K. (2018). Real-time, quantitative detection of Vampirovibrio chlorellavorus, a bacterial pathogen of Chlorella sorokiniana. J. Appl. Phycol., 1-13. doi:https://doi.org/10.1007/s10811-018-1659-z
• Brown, J. K. (2019). First report of cotton leafroll dwarf virus associated with cotton blue disease symptoms in Alabama. Plant Dis.. doi:https://doi.org/10.1094/PDIS-09-18-1550-PDN (on-line Jan 21, 2019)
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  Peer-reviewed Short Report (Disease Note)
• Brown, J. K., Hameed, S., Raja, N. I., & Yasmin, S. (2018). First report of Tomato leaf curl virus and Croton yellow vein mosaic betasatellite infecting chilli plants in Pakistan.. New Disease Reports, 37(1), 10-10. doi:10.5197/j.2044-0588.2018.037.010
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  Leaf curl disease poses a major constraint to chilli (Capsicum annuum) production in Pakistan. In October 2014, chilli plants exhibiting geminivirus-like symptoms, including leaf curling and stunting were observed at the National…
• Gao, S., Samaniego, B., Steichen, S., Cervantes, D., Brown, J. K., Ogden, K. L., & Toscano, L. (2018). Harvesting of chlorella sorokiniana by fungal-assisted palletization, and cellulase production: a case of study. J. Biobased Mater. Bioenergy, 12, 493-505. doi:https://doi.org/10.1166/jbmb.2018.1798
• Ilyas, M., Avelar, S., Schuch, U. K., & Brown, J. K. (2018). First report of an emaravirus associated with witches’ broom disease and eriophyid mite infestations of the blue palo verde tree in Arizona. Plant Disease, 102(Issue 9). doi:10.1094/pdis-01-18-0124-pdn
• Park, S. H., Kyndt, J., Chougule, K., Park, J. J., & Brown, J. K. (2018). Low-phosphate-selected auxenochlorella protothecoides redirects phosphate to essential pathways while producing more biomass. PLoS ONE, 13(Issue 6). doi:10.1371/journal.pone.0198953
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  Despite the capacity to accumulate ~70% w/w of lipids, commercially produced unicellular green alga A. protothecoides may become compromised due to the high cost of phosphate fertilizers. To address this limitation A. protothecoides was selected for adaptation to conditions of 100× and 5× lower phosphate and peptone, respectively, compared to ‘wild-type media’. The A. protothecoides showed initial signs of adaptation by 45–50 days, and steady state growth at ~100 days. The low phosphate (P)-adapted strain produced up to ~30% greater biomass, while total lipids (~10% w/w) remained about the same, compared to the wild-type strain. Metabolomic analyses indicated that the low P-adapted produced 3.3-fold more saturated palmitic acid (16:0) and 2.2-fold less linolenic acid (18:3), compared to the wild-type strain, resulting in an ~11% increase in caloric value, from 19.5kJ/g for the wild-type strain to 21.6kJ/g for the low P-adapted strain, due to the amounts and composition of certain saturated fatty acids, compared to the wild type strain. Biochemical changes in A. protothecoides adapted to lower phosphate conditions were assessed by comparative RNA-Seq analysis, which yielded 27,279 transcripts. Among them, 2,667 and 15 genes were significantly down- and up-regulated, at >999-fold and >3-fold (adjusted p-value
• Ahmad, A., Zia-Ur-Rehman, M., Hameed, U., Rao, A. Q., Ahad, A., Yasmeen, A., Akram, F., Bajwa, K. S., Scheffler, J., Nasir, I. A., Shahid, A. A., Iqbal, M. J., Husnain, T., Haider, M. S., & Brown, J. K. (2017). Engineered disease resistance in cotton using RNA-interference to knock down Cotton leaf curl Kokhran virus-burewala and cotton leaf curl multan betasatellite expression. Viruses, 9(Issue 9). doi:10.3390/v9090257
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  Cotton leaf curl virus disease (CLCuD) is caused by a suite of whitefly-transmitted begomovirus species and strains, resulting in extensive losses annually in India and Pakistan. RNA-interference (RNAi) is a proven technology used for knockdown of gene expression in higher organisms and viruses. In this study, a small interfering RNA (siRNA) construct was designed to target the AC1 gene of Cotton leaf curl Kokhran virus-Burewala (CLCuKoV-Bu) and the βC1 gene and satellite conserved region of the Cotton leaf curl Multan betasatellite (CLCuMB). The AC1 gene and CLCuMB coding and non-coding regions function in replication initiation and suppression of the plant host defense pathway, respectively. The construct, Vβ, was transformed into cotton plants using the Agrobacterium-mediated embryo shoot apex cut method. Results from fluorescence in situ hybridization and karyotyping assays indicated that six of the 11 T1 plants harbored a single copy of the Vβ transgene. Transgenic cotton plants and non-transgenic (susceptible) test plants included as the positive control were challenge-inoculated using the viruliferous whitefly vector to transmit the CLCuKoV-Bu/CLCuMB complex. Among the test plants, plant Vβ-6 was asymptomatic, had the lowest amount of detectable virus, and harbored a single copy of the transgene on chromosome six. Absence of characteristic leaf curl symptom development in transgenic Vβ-6 cotton plants, and significantly reduced begomoviral-betasatellite accumulation based on real-time polymerase chain reaction, indicated the successful knockdown of CLCuKoV-Bu and CLCuMB expression, resulting in leaf curl resistant plants.
• Alabi, O. J., Al Rwahnih, M., Jifon, J. L., Sétamou, M., Brown, J. K., Gregg, L., & Park, J. W. (2017). A mixed infection of Lettuce chlorosis virus, papaya ringspot virus, and tomato yellow leaf curl virus-IL detected in a Texas papaya orchard affected by a virus-like disease outbreak. Plant Disease, 101(Issue 7). doi:10.1094/pdis-01-17-0118-re
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  Severe virus-like symptoms consisting of mosaic, distortion, yellowing, and brittleness were observed on papaya plants in a 20-ha orchard in South Texas during the 2014–15 growing season. Incidence of symptomatic plants increased from ∼40 to 100% within 6 months of the outbreak; the most severely affected plants were stunted, and fruit yield and quality were reduced compared with asymptomatic plants. The orchard papaya plant virome was explored using the Illumina NextSeq 500 platform and results were validated by Sanger DNA sequencing of complete viral genomes obtained by PCR amplification. The combined results revealed the presence of Papaya ringspot virus (PRSV; Potyvirus), Lettuce chlorosis virus (LCV; Crinivirus), and Tomato yellow leaf curl virus-IL (TYLCV-IL; Begomovirus). The RT-PCR analyses of leaves from 51 randomly sampled papaya plants indicated the presence of PRSV, LCV, and TYLCV-IL in 100, 39.2, and 15.7% of the samples, respectively. Plants infected with PRSV, in combination with LCV and/or TYLCV-IL, exhibited more severe symptoms compared with plants infected with PRSV alone. Furthermore, successful whitefly-mediated transmission of TYLCV-IL and LCV was accomplished by exposing virus-free papaya seedlings to viruliferous Bemisia tabaci (Genn.) under greenhouse conditions. The results of this study document a new host record for LCV and the first successful whitefly-mediated transmission of TYLCV-IL and LCV to papaya. As a perennial crop, infected papaya serving as an over-seasoning reservoir for TYLCV-IL and LCV, presents a new challenge to viral disease management in papaya orchards.
• Andreason, S. A., Arif, M., Brown, J. K., Ochoa-Corona, F., Fletcher, J., & Wayadande, A. (2017). Single-Target and Multiplex Discrimination of Whiteflies (Hemiptera: Aleyrodidae) Bemisia tabaci and Trialeurodes vaporariorum with Modified Priming Oligonucleotide Thermodynamics. Journal of Economic Entomology, 110(Issue 4). doi:10.1093/jee/tox125
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  The whitefly species Bemisia tabaci (Gennadius) and Trialeurodes vaporariorum (Westwood) are worldwide agricultural pests and virus vectors. Bemisia tabaci, in particular, is often transported internationally via trade routes leading to potential introductions of exotic whiteflies or plant viruses. Quick identification of agriculturally important whiteflies can facilitate interventions that prevent these cross-border introductions. Polymerase chain reaction (PCR) primers were designed to amplify the mitochondrial cytochrome oxidase I gene (mtCOI) sequence of members of the B. tabaci complex, MEAM1, MED, and NW, and T. vaporariorum. Primers incorporated an A/T-rich overhang sequence at the 5′ terminus (5′ flap) to test for increased primer sensitivity and assay efficiency. Single-target and multiplex endpoint PCR assays with the eight primer sets were performed using genomic DNA template extracted from individual adult whiteflies. Resultant PCR amplicons obtained for B. tabaci MEAM1, MED, and NW, and T. vaporariorum primers with the 5′ flap were 559-, 717-, 353-, and 258-bp, respectively, and without the 5′ flap were 550-, 712-, 329-, and 252-bp in length, respectively. In single-target and multiplex reactions, specific amplification was achieved using both the unmodified and 5′ flap-modified primers. Sequencing and phylogenetic analysis confirmed primer-target amplification specificity. Using these primer sets in single-target or multiplex PCR allows for quick discrimination and specific identification of B. tabaci complex members and T. vaporariorum, and the addition of 5′A/T-rich overhang sequences increases the sensitivity and amplification of some primer sets.
• Brown, J. K. (2017). A mixed infection of Lettuce chlorosis virus, Papaya ringspot virus, and Tomato yellow leaf curl virus-IL detected in a Texas papaya orchard affected by a virus-like disease outbreak. Plant Disease, 101, 1094-1102.
• Brown, J. K. (2017). Colonization and intrusive invasion of potato psyllid by ‘Ca. Liberibacter solanacearum’. Phytopathology, 107, 36-49. doi:10.1094/ PHYTO-03-16-0149-R.
• Brown, J. K. (2017). Diversity and distribution of the Bemisia tabaci complex in Pakistan. Journal of Economic Entomology, 110(6), 2295-2300. doi:10.1093/jee/tox221
• Brown, J. K. (2017). Engineered disease resistance in cotton using RNA-interference to knock down Cotton leaf curl Kokhran virus-Burewala and Cotton leaf curl Multan betasatellite expression. Viruses, 9(9), 257.
• Brown, J. K. (2017). Functional analysis of whitefly B biotype gut gene expression by RNAi knockdown and phenotypic analysis. PLoS One, 12(1), e0168921.doi:10.1371/journal.pone.016892.
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  Vyas, M., Raza, A., Ali, A.M., Ashraf, M.A., Mansoor, S., Ahmad, A.S., and Brown, J.K. 2017. Knock down of whitefly gut gene expression and mortality by orally delivered gut gene-specific dsRNA. PLoS ONE 12(1): e0168921.doi:10.1371/journal.pone.016892.
• Brown, J. K. (2017). Genome sequencing of the sweetpotato whitefly Bemsia tabaci MED/Q. GigaScience Database, 6(5), 1-7. doi:10.1093/gigascience/gix018
• Brown, J. K. (2017). Genome sequencing of the sweetpotato whitefly Bemsia tabaci MED/Q. Gigascience, 6(1-7). doi:10.1093/gigascience/gix018/ [Supporting data: doi 10.5524/100286].
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  Xie, W., Chen, C., Yang, Z., Guo, L., Yang, X., Wang, D., Chen, M., Huang, J., Wen, Y., Zeng, Y., Liu, Y., Xia, J., Tian, L., Cui, H., Wu, Q., Wang, S., Xu, B., Li, X., Xinqiu Tan, X., Ghanim, M., Qiu, B., Pan, H., Chu, D., Delatte, H., Maruthi, M.N., Ge, F., Zhou,X., Wang, X., Wan, F., Du, Y., Luo, C., Yan, F., Preisser, E.L., Jiao, X., Coates, B. S., Zhao, J., Gao, Q., Xia, J., Yin, Y., Yong Liu, Y., Brown, J.K, Zhou, X., and Zhang, Y. 2017. Genome sequencing of the sweetpotato whitefly Bemsia tabaci MED/Q.
• Brown, J. K. (2017). Knock down of whitefly gut gene expression and mortality by orally delivered gut gene-specific dsRNA. PLos ONE, 12(1). doi:10.1371/journal.pone.016892.
• Brown, J. K. (2017). Molecular characterization of a novel bipartite begomovirus isolated from Lycianthes biflora in China. Arch. Virol., 162(8), 2473-2476. doi:doi:10.1007/s00705-017-3333-1.
• Brown, J. K. (2017). Molecular diagnostic development for two begomovirus-betasatellite complexes undergoing diversification: A case study. Virus Research, 241, 29-41. doi:http://doi.org/10.1016/j.virusres.2017.04.014.
• Brown, J. K. (2017). Occurrence of Pepper mild mottle virus (PMMoV) in groundwater from a karst aquifer system in the Yucatan Peninsula, Mexico.. Food and Environmental Virology, 9(4), 487-497. doi:10.1007/s12560-017-9309-1.
• Brown, J. K. (2017). Previously-elusive badnaviruses associated with symptomatic cacao in Trinidad, the first cacao-infecting viruses in the New World. Arch. Virol., 162(5), 1363-1371. doi:10.1007/s00705-017-3235-2.
• Brown, J. K. (2017). Single-target and multiplex discrimination of whiteflies (Hemiptera: Aleyrodidae) Bemisia tabaci and Trialeurodes vaporariorum using modified priming oligonucleotide thermodynamics. J. Econ. Entomol, 110(4), 1-10. doi:https://doi.org/10.1093/jee/tox125.
• Brown, J. K. (2017). The proposed new species, Cacao red vein virus, and three previously recognized badnaviruses are associated with cacao swollen shoot disease. Virology Journal, 14(199). doi:10.1186/s12985-017-0866-6.
• Brown, J. K. (2017). Unexpected genome variability at multiple loci suggests Cacao swollen shoot virus comprises multiple, divergent molecular variants. J Emerg Virol, 3(1). doi:http://dx.doi.org/10.16966/2473-1846.128.
• Brown, J. K., Ur-Rehman, M. Z., Avelar, S., Chingandu, N., Hameed, U., Haider, S., & Ilyas, M. (2017). Molecular diagnostic development for begomovirus-betasatellite complexes undergoing diversification: A case study. Virus Research, 241(Issue). doi:10.1016/j.virusres.2017.04.014
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  At least five begomoviral species that cause leaf curl disease of cotton have emerged recently in Asia and Africa, reducing fiber quality and yield. The potential for the spread of these viruses to other cotton-vegetable growing regions throughout the world is extensive, owing to routine, global transport of alternative hosts of the leaf curl viruses, especially ornamentals. The research reported here describes the design and validation of polymerase chain reaction (PCR) primers undertaken to facilitate molecular detection of the two most-prevalent leaf curl-associated begomovirus-betasatellite complexes in the Indian Subcontinent and Africa, the Cotton leaf curl Kokhran virus-Burewala strain and Cotton leaf curl Gezira virus, endemic to Asia and Africa, respectively. Ongoing genomic diversification of these begomoviral-satellite complexes was evident based on nucleotide sequence alignments, and analysis of single nucleotide polymorphisms, both factors that created new challenges for primer design. The additional requirement for species and strain-specific, and betasatellite-specific primer design, imposes further constraints on primer design and validation due to the large number of related species and strains extant in ‘core leaf curl virus complex’, now with expanded distribution in south Asia, the Pacific region, and Africa-Arabian Peninsula that have relatively highly conserved coding and non-coding regions, which precludes much of the genome-betasatellite sequence when selecting primer ‘targets’. Here, PCR primers were successfully designed and validated for detection of cloned viral genomes and betasatellites for representative ‘core leaf curl’ strains and species, distant relatives, and total DNA isolated from selected plant species. The application of molecular diagnostics to screen plant imports prior to export or release from ports of entry is expected to greatly reduce the likelihood of exotic leaf curl virus introductions that could dramatically affect the production of cotton as well as vegetable and ornamental crop hosts.
• Chingandu, N., Kouakou, K., Aka, R., Ameyaw, G., Gutierrez, O. A., Herrmann, H. W., & Brown, J. K. (2017). The proposed new species, cacao red vein virus, and three previously recognized badnavirus species are associated with cacao swollen shoot disease. Virology Journal, 14(Issue 1). doi:10.1186/s12985-017-0866-6
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  Background: Cacao swollen shoot virus (CSSV), Cacao swollen shoot CD virus (CSSCDV), and Cacao swollen shoot Togo A virus (CSSTAV) cause cacao swollen shoot disease (CSSD) in West Africa. During 2000-2003, leaf and shoot-swelling symptoms and rapid tree death were observed in cacao in Cote d'Ivoire and Ghana. Molecular tests showed positive infection in only ~50-60% of symptomatic trees, suggesting the possible emergence of an unknown badnavirus. Methods: The DNA virome was determined from symptomatic cacao samples using Illumina-Hi Seq, and sequence accuracy was verified by Sanger sequencing. The resultant 14, and seven previously known, full-length badnaviral genomic and RT-RNase H sequences were analyzed by pairwise distance analysis to resolve species relationships, and by Maximum likelihood (ML) to reconstruct phylogenetic relationships. The viral coding and non-coding sequences, genome organization, and predicted conserved protein domains (CPDs) were identified and characterized at the species level. Results: The 21 CSSD-badnaviral genomes and RT-RNase H sequences shared 70-100% and 72-100% identity, respectively. The RT-RNase H analysis predicted four species, based on an ≥80% species cutoff. The ML genome sequence tree resolved three well-supported clades, with ≥70% bootstrap, whereas, the RT-RNase H phylogeny was poorly resolved, however, both trees grouped CSSD isolates within one large clade, including the newly discovered Cacao red vein virus (CRVV) proposed species. The genome arrangement of the four species consists of four, five, or six predicted open reading frames (ORFs), and the CPDs have similar architectures. By comparison, two New World cacao-infecting badnaviruses encode four ORFs, and harbor CPDs like the West African species. Conclusions: Three previously recognized West African cacao-infecting badnaviral species were identified, and a fourth, previously unidentified species, CRVV, is described for the first time. The CRVV is a suspect causal agent of the rapid decline phenotype, however Koch's Postulates have not been proven. To reconcile viral evolutionary with epidemiology considerations, more detailed information about CSSD-genomic variability is essential. Also, the functional basis for the multiple genome arrangements and subtly distinct CPD architectures among cacao-infecting badnaviruses is poorly understood. New knowledge about functional relationships may help explain the diverse symptomatologies observed in affected cacao trees.
• Chingandu, N., Zia-ur-rehman, M., Sreenivasan, T. N., Surujdeo-Maharaj, S., Umaharan, P., Gutierrez, O. A., & Brown, J. K. (2017). Molecular characterization of previously elusive badnaviruses associated with symptomatic cacao in the New World. Archives of Virology, 162(Issue 5). doi:10.1007/s00705-017-3235-2
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  Suspected virus-like symptoms were observed in cacao plants in Trinidad during 1943, and the viruses associated with these symptoms were designated as strains A and B of cacao Trinidad virus (CTV). However, viral etiology has not been demonstrated for either phenotype. Total DNA was isolated from symptomatic cacao leaves exhibiting the CTV A and B phenotypes and subjected to Illumina HiSeq and Sanger DNA sequencing. Based on de novo assembly, two apparently full-length badnavirus genomes of 7,533 and 7,454 nucleotides (nt) were associated with CTV strain A and B, respectively. The Trinidad badnaviral genomes contained four open reading frames, three of which are characteristic of other known badnaviruses, and a fourth that is present in only some badnaviruses. Both badnaviral genomes harbored hallmark caulimovirus-like features, including a tRNAMet priming site, a TATA box, and a polyadenylation-like signal. Pairwise comparisons of the RT-RNase H region indicated that the Trinidad isolates share 57-71% nt sequence identity with other known badnaviruses. Based on the system for badnavirus species demarcation in which viruses with less than 80% nt sequence identity in the RT-RNase gene are considered members of separate species, these isolates represent two previously unidentified badnaviruses, herein named cacao mild mosaic virus and cacao yellow vein banding virus, making them the first cacao-infecting badnaviruses identified thus far in the Western Hemisphere.
• Cicero, J. M., Fisher, T. W., Qureshi, J. A., Stansly, P. A., & Brown, J. K. (2017). Colonization and intrusive invasion of potato psyllid by 'Candidatus Liberibacter solanacearum'. Phytopathology, 107(Issue 1). doi:10.1094/phyto-03-16-0149-r
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  Previous studies have shown that the fastidious bacterial plant pathogen 'Candidatus Liberibacter solanacearum' (CLso) is transmitted circulatively and propagatively by the potato psyllid (PoP) Bactericera cockerelli. In this study, the temporal and spatial interrelationships between CLso PoP were investigated by scanning electron microscopy of the digestive system of PoP immature and adult instars and salivary glands of adults post CLso ingestion. CLso biofilms were not detectable on the outer midgut surface of the first and second instars; however, for third to fifth instars and teneral and mature adults, biofilms were observed in increasing numbers in each successive developmental stage. In adult PoP midguts, CLso cells were observed between the basal lamina and basal epithelial cell membranes; in basal laminar perforations, on the outer basal laminar surface, and in the ventricular lumen, epithelial cytosol, and filter chamber periventricular space. CLso were also abundantly visible in the salivary gland pericellular spaces and in the epidermal cell cytosol of the head. Collectively, these results point to an intrusive, systemic invasion of PoP by CLso that employs an endo/exocytosis-like mechanism, in the context of a propagative, circulative mode of transmission.
• Masood, M., Amin, I., Hassan, I., Mansoor, S., Brown, J. K., & Briddon, R. W. (2017). Diversity and Distribution of Cryptic Species of the Bemisia tabaci (Hemiptera: Aleyrodidae) complex in Pakistan. Journal of Economic Entomology, 110(Issue 6). doi:10.1093/jee/tox221
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  Bemisia tabaci (Gennadius; Hempitera: Aleyrodidae) is considered to be a cryptic (sibling) species complex, the members of which exhibit morphological invariability while being genetically and behaviorally distinct. Members of the complex are agricultural pests that cause direct damage by feeding on plants, and indirectly by transmitting viruses that cause diseases leading to reduced crop yield and quality. In Pakistan, cotton leaf curl disease, caused by multiple begomovirus species, is the most economically important viral disease of cotton. In the study outlined here, the diversity and geographic distribution of B. tabaci cryptic species was investigated by analyzing a taxonomically informative fragment of the mitochondrial cytochrome c oxidase 1 gene (mtCOI-3'). The mtCOI-3 sequence was determined for 285 adult whiteflies and found to represent six cryptic species, the most numerous being Asia II-1 and Middle East Asia Minor 1 (MEAM-1), the later also referred to as the B-biotype, which was previously thought to be confined to Sindh province but herein, was also found to be present in the Punjab province. The endemic Asia I was restricted to Sindh province, while an individual in the Asia II-8 was identified in Pakistan for the first time. Also for the first time, samples were collected from northwestern Pakistan and Asia II-1 was identified. Results indicate that in Pakistan the overall diversity of B. tabaci cryptic species is high and, based on comparisons with findings from previous studies, the distribution is dynamic.
• Rosiles-González, G., Ávila-Torres, G., Moreno-Valenzuela, O. A., Acosta-González, G., Leal-Bautista, R. M., Grimaldo-Hernández, C. D., Brown, J. K., Chaidez-Quiroz, C., Betancourt, W. Q., Gerba, C. P., & Hernández-Zepeda, C. (2017). Occurrence of Pepper Mild Mottle Virus (PMMoV) in Groundwater from a Karst Aquifer System in the Yucatan Peninsula, Mexico. Food and Environmental Virology, 9(Issue 4). doi:10.1007/s12560-017-9309-1
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  The Yucatan Peninsula of Mexico hosts a karst aquifer system that is the only source of freshwater for the area; however, it is vulnerable to human-mediated contamination. Pepper mild mottle virus (PMMoV) is one of the most abundant RNA viruses associated with human feces, making it a viable indicator for tracking fecal pollution in aquatic environments, including groundwater. In this study, groundwater samples collected from a karst aquifer from fresh and brackish water locations were analyzed for fecal indicator bacteria, somatic and male F+ specific coliphages, and PMMoV during the rainy and dry seasons. Total coliform bacteria were detected at all sites, whereas Escherichia coli were found at relatively low levels 0.05). Physicochemical and indicator bacteria were not correlated with PMMoV concentrations. The abundance and prevalence of PMMoV in the karst aquifer may reflect its environmental persistence and its potential as a fecal indicator in this karst aquifer system.
• Unkefer, C. J., Sayre, R. T., Magnuson, J. K., Anderson, D. B., Baxter, I., Blaby, I. K., Brown, J. K., Carleton, M., Cattolico, R. A., Dale, T., Devarenne, T. P., Downes, C. M., Dutcher, S. K., Fox, D. T., Goodenough, U., Jaworski, J., Holladay, J. E., Kramer, D. M., Koppisch, A. T., , Lipton, M. S., et al. (2017). Review of the algal biology program within the National Alliance for Advanced Biofuels and Bioproducts. Algal Research, 22. doi:10.1016/j.algal.2016.06.002
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  In 2010, when the National Alliance for Advanced Biofuels and Bioproducts (NAABB) consortium began, little was known about the molecular basis of algal biomass or oil production. Very few algal genome sequences were available and efforts to identify the best-producing wild species through bioprospecting approaches had largely stalled after the U.S. Department of Energy's Aquatic Species Program. This lack of knowledge included how reduced carbon was partitioned into storage products like triglycerides or starch and the role played by metabolite remodeling in the accumulation of energy-dense storage products. Furthermore, genetic transformation and metabolic engineering approaches to improve algal biomass and oil yields were in their infancy. Genome sequencing and transcriptional profiling were becoming less expensive, however; and the tools to annotate gene expression profiles under various growth and engineered conditions were just starting to be developed for algae. It was in this context that an integrated algal biology program was introduced in the NAABB to address the greatest constraints limiting algal biomass yield. This review describes the NAABB algal biology program, including hypotheses, research objectives, and strategies to move algal biology research into the twenty-first century and to realize the greatest potential of algae biomass systems to produce biofuels.
• Unkefer, C., Molnar, I., Ogden, K. L., Olivares, J., Brown, J. K., & 15 other cauthors, . (2017). Review of the algal biology program within the National Alliance for Advanced Biofuels and Bioproducts. Algal Research, 22, 187-215. doi:10.1016/j.algal.2016.06.002
• Vyas, M., Raza, A., Ali, M. Y., Ashraf, M. A., Mansoor, S., Shahid, A. A., & Brown, J. K. (2017). Knock down of whitefly gut gene expression and mortality by orally delivered gut gene-specific dsRNAs. PLoS ONE, 12(Issue 1). doi:10.1371/journal.pone.0168921
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  Control of the whitefly Bemisia tabaci (Genn.) agricultural pest and plant virus vector relies on the use of chemical insecticides. RNA-interference (RNAi) is a homology-dependent innate immune response in eukaryotes, including insects, which results in degradation of the corresponding transcript following its recognition by a double-stranded RNA (dsRNA) that shares 100% sequence homology. In this study, six whitefly 'gut' genes were selected from an in silico-annotated transcriptome library constructed from the whitefly alimentary canal or 'gut' of the B biotype of B. tabaci, and tested for knock down efficacy, post-ingestion of dsRNAs that share 100% sequence homology to each respective gene target. Candidate genes were: Acetylcholine receptor subunit α, Alpha glucosidase 1, Aquaporin 1, Heat shock protein 70, Trehalase1, and Trehalose transporter1. The efficacy of RNAi knock down was further tested in a gene-specific functional bioassay, and mortality was recorded in 24 hr intervals, six days, post-treatment. Based on qPCR analysis, all six genes tested showed significantly reduced gene expression. Moderate-to-high whitefly mortality was associated with the down-regulation of osmoregulation, sugar metabolism and sugar transport-associated genes, demonstrating that whitefly survivability was linked with RNAi results. Silenced Acetylcholine receptor subunit α and Heat shock protein 70 genes showed an initial low whitefly mortality, however, following insecticide or high temperature treatments, respectively, significantly increased knockdown efficacy and death was observed, indicating enhanced post-knockdown sensitivity perhaps related to systemic silencing. The oral delivery of gut-specific dsRNAs, when combined with qPCR analysis of gene expression and a corresponding gene-specific bioassay that relates knockdown and mortality, offers a viable approach for functional genomics analysis and the discovery of prospective dsRNA biopesticide targets. The approach can be applied to functional genomics analyses to facilitate, species-specific dsRNA-mediated control of other non-model hemipterans.
• Xie, W., Chen, C., Yang, Z., Guo, L., Yang, X., Wang, D., Chen, M., Huang, J., Wen, Y., Zeng, Y., Liu, Y., Xia, J., Tian, L., Cui, H., Wu, Q., Wang, S., Xu, B., Li, X., Tan, X., , Ghanim, M., et al. (2017). Genome sequencing of the sweetpotato whitefly Bemisia tabaci MED/Q. GigaScience, 6(Issue 5). doi:10.1093/gigascience/gix018
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  The sweetpotato whitefly Bemisia tabaci is a highly destructive agricultural and ornamental crop pest. It damages host plants through both phloem feeding and vectoring plant pathogens. Introductions of B. tabaci are difficult to quarantine and eradicate because of its high reproductive rates, broad host plant range, and insecticide resistance. A total of 791 Gb of raw DNA sequence from whole genome shotgun sequencing, and 13 BAC pooling libraries were generated by Illumina sequencing using different combinations of mate-pair and pair-end libraries. Assembly gave a final genome with a scaffold N50 of 437 kb, and a total length of 658 Mb. Annotation of repetitive elements and coding regions resulted in 265.0 Mb TEs (40.3%) and 20 786 protein-coding genes with putative gene family expansions, respectively. Phylogenetic analysis based on orthologs across 14 arthropod taxa suggested that MED/Q is clustered into a hemipteran clade containing A. pisum and is a sister lineage to a clade containing both R. prolixus and N. lugens. Genome completeness, as estimated using the CEGMA and Benchmarking Universal Single-Copy Orthologs pipelines, reached 96% and 79%. These MED/Q genomic resources lay a foundation for future 'pan-genomic' comparisons of invasive vs. noninvasive, invasive vs. invasive, and native vs. exotic Bemisia, which, in return, will open up new avenues of investigation into whitefly biology, evolution, and management.
• Yasmin, S., Raja, N. I., Hameed, S., & Brown, J. K. (2017). First association of Pedilanthus leaf curl virus, Papaya leaf curl virus, Cotton leaf curl Kokhran virus, and Papaya leaf curl betasatellite with Symptomatic chilli pepper in Pakistan. Plant Disease, 101(Issue 12). doi:10.1094/pdis-06-17-0883-pdn
• Zia-Ur-Rehman, M., Hameed, U., Ali, C. A., Haider, M. S., & Brown, J. K. (2017). First report of Chickpea chlorotic dwarf virus infecting okra in Pakistan. Plant Disease, 101(Issue 7). doi:10.1094/pdis-11-16-1626-pdn
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  Chickpea chlorotic dwarf virus (CpCDV) is a member of the genus Mastrevirus, family Geminiviridae. Mastreviruses are leafhopper-transmitted, and have a single-stranded, circular DNA genome with four open reading frames, two each encoded in the virion-and complementary-sense orientation, separated by two intergenic regions. Okra (Abelmoschus esculentus) is an important cultivated vegetable in Pakistan and is reported to be infected by a number of begomoviruses. In June 2012, during a field survey in okra cultivations in the Vehari district of Punjab, Pakistan, approximately 15% of okra plants were exhibiting leaf curling, yellowing, and vein thickening symptoms, in two locations of the city. Total DNA was extracted from leaves collected from five symptomatic plants using the CTAB method (†). The circular DNA fraction was enriched using rolling circle amplification (RCA) (TempliPhi kit; GE Healthcare, U.S.A.), digested with EcoRI to obtain a full-length viral-size genome(s) of ∼2,600 base pairs (bp), and cloned into the pGEM-3Zf+ plasmid vector (Promega, Madison, WI). The cloned inserts were subjected to Sanger DNA sequencing, yielding three 2,586-bp sequences that shared high nucleotide (nt) sequence identity with previously reported CpCDV isolates, based on BLASTn analysis against the NCBI-GenBank database. All complete CpCDV genome sequences were downloaded, and together with the chickpea-associated CpCDV-like sequences determined herein, were subjected to pairwise distance analysis using SDT 1.2 software (†). The three sequences shared 100% nt identity with each other and 98.8% nt identity with CpCDV strain C (AM850136) isolated from chickpea (Cicer arietinum) from Layyah, Pakistan. As the three sequences representing both locations were identical, so the only one sequence was used in further analysis. Using the mastrevirus species and strain threshold of 78% and >94% nt identity, respectively (†), the sequence described here (KT719391) represents the first CpCDV strain C isolate associated with okra in Pakistan. Based on phylogenetic analysis using maximum-likelihood (1,000 bootstrap iterations; >70% support), implemented in MEGA6, the sequence obtained here grouped with all other strain C isolates of CpDCV. The presence of CpCDV in three symptomatic okra plants was confirmed by Southern blot hybridization using a digoxygenin-labeled probe, as described (†). Overall, 12 strains of CpCDV, A-L, have been reported from diverse dicot hosts (†). CpCDV strain C has been most frequently isolated from chickpea, but most recently it has been isolated from tomato (†) and cucumber (†) in Pakistan. To our knowledge, this is the first report of CpCDV associated with symptomatic okra plants in Pakistan. This finding supports the hypothesis that CpCDV has a broader than expected host range, and consequently, may infect additional plant species.
• Alabi, O. J., Al Rwahnih, M., Brown, J. K., Idris, A. M., Gregg, L., Kmieciak, E., Sétamou, M., & Jifon, J. L. (2016). First report of Papaya (Carica papaya) naturally infected with the introduced Tomato yellow leaf curl virus-Israel. Plant Disease, 100(Issue 9). doi:10.1094/pdis-04-16-0469-pdn
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  Previously unreported virus-like disease symptoms consisting of severe mosaic and interveinal chlorosis, distortion, and brittleness were observed during the fall/spring of 2014 to 2015 in a 50-ha commercial papaya orchard planted with variety Red Maradol in the Rio Grande Valley of Texas. Populations of the silverleaf whitefly (Bemisia tabaci Genn.) and the green peach aphid (Myzus persicae Sulzer) were observed feeding and reproducing on papaya plants. Incidence of symptomatic trees increased from 40 to 100% within 6 months after the disease was first noted during fall 2014 and the most severely affected plants were stunted, with reduced or no fruit set, and poor fruit quality. To explore the papaya plant virome, a cDNA library constructed from DNase-treated total RNA extracts of leaf samples pooled from eight randomly collected symptomatic trees was subjected to high-throughput sequencing (HTS) using the Illumina NextSeq 500 platform, and the HTS data obtained were analyzed as described previously (Alabi et al. 2015). The analysis revealed the presence of only one 301-nt contig mapped to the genome of Tomato yellow leaf curl virus-Israel (TYLCV-IL) in plants also harboring two RNA viruses (data not shown). To confirm HTS results, total DNA purified from the original eight symptomatic leaf tissues was used as templates for rolling cycle amplification (RCA) using the TempliPhi 100 Amplification Kit (GE Healthcare Biosciences Corp., Cranbury, NJ). The RCA templates were used in PCR with abutting primers (TYPap-C1a_F: 5′-GCTCGTAGAGGGTGACGAAG and TYPap-C1a_R: 5′-GAGCCACTGTTCGCAAGTAT, and TYPap-C2a_F: 5′-GATAACAGAACACAGCCAGAGG with TYPap-C2a_R: 5′-TGGTTCATTAGAAATGGCCTC) designed based on the HTS sequences. The ∼2.7 kbp products from three papaya samples were cloned individually into the pCR2.1 TOPO-TA vector (Life Technologies, Carlsbad, CA), and the DNA sequence was determined bidirectionally for each plasmid. The 2,781-nt long complete viral genomes from three samples (KX024639, KX024643, and KX024647) shared 99 to 100% nt identity with each other, and 98 to 99% nt identity with their closest relative, a TYLCV-IL isolate from Sinaloa, Mexico (EF523478). Further analysis of the full-length genome of these papaya isolates revealed that their closest relatives in the old world, at 98% nt identity, are isolates from Morocco (EF060196) and the Netherlands (FJ439569). Unlike the TYLCV-IL isolates reported earlier on tomato plants from new world locations in Texas (EF110890), Arizona (EF210554), and Grenada (FR851297), the papaya isolates contained no deletion in the intergenic region located between the nt coordinates (2,700 and 2,728), suggesting a possible recent or previously undetected TYLCV-IL introduction in Texas from movement within or outside North America. Whether TYLCV-IL infection alone causes symptoms in papaya in the absence of the other viruses detected here is not known because all plants harbored TYLCV-IL together with other viruses. The wide host range of TYLCV includes tomato and other cultivated and noncultivated plants (Díaz-Pendon et al. 2010). Here we report the first detection of TYLCV-IL infecting papaya. Papaya plants, when grown as perennials, can serve as important reservoirs of viruses that infect susceptible crops in the vicinity. Thus, this discovery presents new challenges to virus disease management in papaya, tomato, and other annual and perennial crops grown in South Texas.
• Brown, J. K. (2016). First Report of Chayote yellow mosaic virus infecting bitter melon Momordica charantia exhibiting yellow mosaic symptoms in Benin, Nigeria and Togo (Short report). Plant Dis., 100(1), 1031.
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  Leke, W., Mignouna, D.B., Brown, J.K., and Fondong, V.N. 2016. First report of Chayote yellow mosaic virus infecting bitter melon Momordica charantia exhibiting yellow mosaic symptoms in Benin, Nigeria and Togo. Plant Dis 100: 1031. http://dx.doi.org/10.1094/PDIS-11-15-1276-PDN.Plant Dis. 100:1, 2016.published online as http://dx.doi.org/10.1094/PDIS-11-15-1276-PDN.Accepted for publication 15 December 2015.
• Brown, J. K. (2016). First report of Soybean chlorotic blotch virus and West African Asystasia virus infecting cassava and a wild cassava relative in Cameroon and Togo.. New Disease Reports, 33, 24.
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  Leke, W.N., Mignouna, D.B., Brown, J.K., Fondong, V.N. 2016. First report of Soybean chlorotic blotch virus and West African Asystasia virus 1 infecting cassava and a wild cassava relative in Cameroon and Togo. New Disease Reports 33:24. http://dx.doi.org/10.5197/j.2044-0588.2016.033.024
• Brown, J. K. (2016). First report of papaya naturally-infected with the introduced Tomato yellow leaf curl virus-IL. (Short Report). Plant Dis., 100, 1959. doi:http://dx.doi.org/10.1094/PDIS-04-16-0469-PDN.
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  Alabi, O.J., Al Rwahnih, M., Brown, J.K., Idris, A.M., Gregg, L., Kmieciak, E., Sétamou, M., and Jifon, J.L. 2016. First report of papaya naturally-infected with the introduced Tomato yellow leaf curl virus-IL. Plant Dis. 100:1959. http://dx.doi.org/10.1094/PDIS-04-16-0469-PDN.
• Brown, J. K. (2016). Global population structure of a worldwide pest and virus vector: genetic diversity and population history of the Bemisia tabaci sibling species group.. PLoS One, DOI:10.1371/journal.pone.0165105.
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  Hadjistylli, M., Roderick, G.K., and Brown, J.K. 2016. Global population structure of a worldwide pest and virus vector: genetic diversity and population history of the Bemisia tabaci sibling species group. PLOS ONE DOI:10.1371/journal.pone.0165105.
• Brown, J. K. (2016). Localization of Candidatus Liberibacter solanacearum’ and evidence for surface appendages in the potato psyllid vector. Phytopathology, 106((1)), 1-13.
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  Cicero, J. M., Fisher, T.W., and Brown, J.K. 2016. Localization of Candidatus Liberibacter solanacearum’ and evidence for surface appendages in the potato psyllid vector. Phytopathology 106:1-13.
• Brown, J. K. (2016). RNAi-mediated mortality of the whitefly through transgenic expression of doublestranded RNA homologous to acetylcholinesterase and ecdysone receptor in tobacco plants.. Nature.com/ scientificreports/Scientific Reports, 6, 38469. doi:DOI: 10.1038/srep38469
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  Malik, H.J., Raza, A., Amin, I., Scheffler, J.A., Scheffler, B.E., Brown, J.K., and Mansoor, S. 2016. RNAi-mediated mortality of the whitefly through transgenic expression of doublestranded RNA homologous to acetylcholinesterase and ecdysone receptor in tobacco plants. Nature.com/ scientificreports/Scientific Reports 6:38469 | DOI: 10.1038/srep38469.
• Brown, J. K. (2016). The evolution of a process for selecting and prioritizing diseases for recovery plans. Plant Dis., 100:, 1-7.
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  McRoberts, N., C. Thomas, J. K. Brown, F. W. Nutter, J. P. Stack and R. D. Martyn. 2016. The evolution of a process for selecting and prioritizing diseases for recovery plans. Plant Dis. 100:1-7. http://dx.doi.org/10.1094/PDIS-04-15-0457-FE.
• Brown, J. K. (2016). The genome of whitefly Bemisia tabaci MEAM1, a global crop pest, provides novel insights into virus transmission, host adaptation, and insecticide resistance.. BMC Biology, 14, 110. doi:DOI: 10.1186/s12915-016-0321-y.
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  Chen, W., Hasegawa, D.K., Kaur, N., Kliot, A., Pinheiro, P.V., Luan, J., Zheng, Y., Liu, W., Honghe, S., Xu, Y., Luo, Y., Kruse, A., Yang, X., Elimelech, M., Fisher, T.W., MacCoss, M., Johnson, R., Nelson, D.R., Cohen, E., Hunter, W.B., Brown, J.K., Jander, G., Cilia, M., Douglas, A.E., Ghanim, M., Simmons, A.L., Wintermantel, W.M., Ling, K.-S., Fei, Z. 2016. The genome of whitefly Bemisia tabaci MEAM1, a global crop pest, provides novel insights into virus transmission, host adaptation, and insecticide resistance. BMC Biology 14:110. DOI: 10.1186/s12915-016-0321-y.
• Brown, J. K. (2017). Previously-elusive badnaviruses associated with symptomatic cacao in Trinidad, the first cacao-infecting viruses in the New World.. Arch. Virol., doi:10.1007/s00705-017-3235-2..
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  Chingandu, N., Zia-Ur-Rehman, M., Sreenivasan, T.N., Surujdeo-Maharaj, S., Umaharan, P., Guttierez, O.A., and Brown, J.K. 2016. Previously-elusive badnaviruses associated with symptomatic cacao in Trinidad, the first cacao-infecting viruses in the New World. Arch. Virol. doi:10.1007/s00705-017-3235-2.
• Brown, J. K., & Brown, J. K. (2016). Complete genome sequence of a new bipartite begomovirus infecting cotton in Benin Republic in West Africa.. Arch. Virol., Virol. 161:(8), 2329-2333. doi 10.1007/s00705-016-2894-8..
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  Leke, W.N., Khatabi, B., Mignouna, D.B., Brown, J.K., and Fondong, V.N. 2016. Complete genome sequence of a new bipartite begomovirus infecting cotton in Benin Republic in West Africa. Arch Virol. 161(8), 2329-2333. doi 10.1007/s00705-016-2894-8.
• Brown, J. K., & Brown, J. K. (2016). First report on natural reproduction of Bemisia tabaci (Hemiptera: Aleyrodidae) in maize fields (Zea mays L.) in Brazil. Pest Mgmt. Sci., DOI: 10.1002/ps.4259.
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  Quintela, E.; A. Abreu, J. Lima, G. Mascarin, and J.K. Brown. 2016. First report on natural reproduction of Bemisia tabaci (Hemiptera: Aleyrodidae) in maize fields (Zea mays L.) in Brazil. Pest Mgmt. Sci. DOI: 10.1002/ps.4259.
• Brown, J. K., & Brown, J. K. (2016). Review of the algal biology program within the National Alliance for Advanced Biofuels and Bioproducts. Algal Res., http://dx.doi.org/10.1016/j.algal.2016.06.002.
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  Unkefer, C.J., Sayre, R.T., Magnuson, J.K., Anderson, D.B., Baxter; I., Blaby, I.K., Brown, J.K., Carleton, M., Cattolico, R.A., Dale, T., Devarenne, T.P., Downes, C.M., Dutcher, S.K., Fox, D.T., Goodenough, U., Jaworski, J., Holladay, J.E., Kramer; D.M., Koppisch, A.T., Lipton, M.S., Marrone, B.L., McCormick, M., Molnar, I., Mott, J.B, Ogden, K.L., Richardson, J.W., Sabarski, M., et al., 2016. Review of the algal biology program within the National Alliance for Advanced Biofuels and Bioproducts. 2016. Review of the algal biology program within the National Alliance for Advanced Biofuels and Bioproducts. Algal Res. http://dx.doi.org/10.1016/j.algal.2016.06.002.
• Chen, W., Hasegawa, D. K., Kaur, N., Kliot, A., Pinheiro, P. V., Luan, J., Stensmyr, M. C., Zheng, Y., Liu, W., Sun, H., Xu, Y., Luo, Y., Kruse, A., Yang, X., Kontsedalov, S., Lebedev, G., Fisher, T. W., Nelson, D. R., Hunter, W. B., , Brown, J. K., et al. (2016). The draft genome of whitefly Bemisia tabaci MEAM1, a global crop pest, provides novel insights into virus transmission, host adaptation, and insecticide resistance. BMC Biology, 14(Issue 1). doi:10.1186/s12915-016-0321-y
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  Background: The whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) is among the 100 worst invasive species in the world. As one of the most important crop pests and virus vectors, B. tabaci causes substantial crop losses and poses a serious threat to global food security. Results: We report the 615-Mb high-quality genome sequence of B. tabaci Middle East-Asia Minor 1 (MEAM1), the first genome sequence in the Aleyrodidae family, which contains 15,664 protein-coding genes. The B. tabaci genome is highly divergent from other sequenced hemipteran genomes, sharing no detectable synteny. A number of known detoxification gene families, including cytochrome P450s and UDP-glucuronosyltransferases, are significantly expanded in B. tabaci. Other expanded gene families, including cathepsins, large clusters of tandemly duplicated B. tabaci-specific genes, and phosphatidylethanolamine-binding proteins (PEBPs), were found to be associated with virus acquisition and transmission and/or insecticide resistance, likely contributing to the global invasiveness and efficient virus transmission capacity of B. tabaci. The presence of 142 horizontally transferred genes from bacteria or fungi in the B. tabaci genome, including genes encoding hopanoid/sterol synthesis and xenobiotic detoxification enzymes that are not present in other insects, offers novel insights into the unique biological adaptations of this insect such as polyphagy and insecticide resistance. Interestingly, two adjacent bacterial pantothenate biosynthesis genes, panB and panC, have been co-transferred into B. tabaci and fused into a single gene that has acquired introns during its evolution. Conclusions: The B. tabaci genome contains numerous genetic novelties, including expansions in gene families associated with insecticide resistance, detoxification and virus transmission, as well as numerous horizontally transferred genes from bacteria and fungi. We believe these novelties likely have shaped B. tabaci as a highly invasive polyphagous crop pest and efficient vector of plant viruses. The genome serves as a reference for resolving the B. tabaci cryptic species complex, understanding fundamental biological novelties, and providing valuable genetic information to assist the development of novel strategies for controlling whiteflies and the viruses they transmit.
• Cicero, J. M., Fisher, T. J., Stansly, P. A., & Qureshi, J. A. (2017). Colonization and intrusive invasion of potato psyllid by ‘Ca. Liberibacter solanacearum’. Phytopathology, 107, 34-49.
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  Cicero, J.M., Fisher, T.W., Qureshi, J.A., Stansly, P.A., and Brown, J.K. 2017. Colonization and intrusive invasion of potato psyllid by ‘Ca. Liberibacter solanacearum’. Phytopathology107:36-49. Epub 2016 Oct 17 http://dx.doi.org/10.1094/ PHYTO-03-16-0149-R.
• Cicero, J. M., Fisher, T. W., & Brown, J. K. (2016). Localization of Candidatus Liberibacter solanacearum and evidence for surface appendages in the potato psyllid vector. Phytopathology, 106(Issue 2). doi:10.1094/phyto-04-15-0088-r
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  The potato psyllid Bactericera cockerelli is implicated as the vector of the causal agent of zebra chip of potato and vein-greening of tomato diseases. Until now, visual identification of bacteria in the genus Candidatus Liberibacter has relied on direct imaging by light and electron microscopy without labeling, or with whole-organ fluorescence labeling only. In this study, aldehyde fixative followed by a coagulant fixative, was used to process adult psyllids for transmission electron microscopy (TEM) colloidal gold in situ hybridization experiments. Results indicated that Ca. Liberibacter solanacearum (CLso)-specific DNA probes annealed to a bacterium that formed extensive, monocultural biofilms on gut, salivary gland, and oral region tissues, confirming that it is one morphotype of potentially others, that is rod-shaped, approximately 2.5 μ m in diameter and of variable length, and has a rough, granular cytosol. In addition, CLso, prepared from shredded midguts, and negatively stained for TEM, possessed pili- and flagella-like surface appendages. Genes implicating coding capacity for both types of surface structures are encoded in the CLso genome sequence. Neither type was seen for CLso associated with biofilms within or on digestive organs, suggesting that their production is stimulated only in certain environments, putatively, in the gut during adhesion leading to multiplication, and in hemolymph to afford systemic invasion.
• Hadjistylli, M., Roderick, G. K., & Brown, J. K. (2016). Global population structure of a worldwide pest and virus vector: Genetic diversity and population history of the Bemisia tabaci sibling species group. PLoS ONE, 11(Issue 11). doi:10.1371/journal.pone.0165105
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  The whitefly Bemisia tabaci sibling species (sibsp.) group comprises morphologically indiscernible lineages of well-known exemplars referred to as biotypes. It is distributed throughout tropical and subtropical latitudes and includes the contemporary invasive haplotypes, termed B and Q. Several well-studied B. tabaci biotypes exhibit ecological and biological diversity, however, most members are poorly studied or completely uncharacterized. Genetic studies have revealed substantial diversity within the group based on a fragment of the mitochondrial cytochrome oxidase I (mtCOI) sequence (haplotypes), with other tested markers being less useful for deep phylogenetic comparisons. The view of global relationships within the B. tabaci sibsp. group is largely derived from this single marker, making assessment of gene flow and genetic structure difficult at the population level. Here, the population structure was explored for B. tabaci in a global context using nuclear data from variable microsatellite markers. Worldwide collections were examined representing most of the available diversity, including known monophagous, polyphagous, invasive, and indigenous haplotypes. Well-characterized biotypes and other related geographic lineages discovered represented highly differentiated genetic clusters with little or no evidence of gene flow. The invasive B and Q biotypes exhibited moderate to high levels of genetic diversity, suggesting that they stemmed from large founding populations that have maintained ancestral variation, despite homogenizing effects, possibly due to human-mediated among-population gene flow. Results of the microsatellite analyses are in general agreement with published mtCOI phylogenies; however, notable conflicts exist between the nuclear and mitochondrial relationships, highlighting the need for a multifaceted approach to delineate the evolutionary history of the group. This study supports the hypothesis that the extant B. tabaci sibsp. group contains ancient genetic entities and highlights the vast cryptic diversity throughout the genome in the group.
• Leke, W. N., Fondong, V. N., & Khatabi, B. (2016). Illumina sequencing of the first begomovirus infecting fluted pumpkin (Telfairia occidentalis) plants in Cameroon (Annotated sequence record).. Arch. Virol., doi 10.1007/s00705-016-2915-7.
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  Leke, W.N., Khatabi, B., Fondong, V.N., and Brown, J.K. 2016. Illumina sequencing of the first begomovirus infecting fluted pumpkin (Telfairia occidentalis) plants in Cameroon: Annotated sequence record. Arch.Virol doi 10.1007/s00705-016-2915-7.
• Leke, W. N., Khatabi, B., Fondong, V. N., & Brown, J. K. (2016). Complete genome sequence of a new bipartite begomovirus infecting fluted pumpkin (Telfairia occidentalis) plants in Cameroon. Archives of Virology, 161(Issue 8). doi:10.1007/s00705-016-2915-7
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  The complete genome sequence was determined and characterized for a previously unreported bipartite begomovirus from fluted pumpkin (Telfairiaoccidentalis, family Cucurbitaceae) plants displaying mosaic symptoms in Cameroon. The DNA-A and DNA-B components were ~2.7 kb and ~2.6 kb in size, and the arrangement of viral coding regions on the genomic components was like those characteristic of other known bipartite begomoviruses originating in the Old World. While the DNA-A component was more closely related to that of chayote yellow mosaic virus (ChaYMV), at 78 %, the DNA-B component was more closely related to that of soybean chlorotic blotch virus (SbCBV), at 64 %. This newly discovered bipartite Old World virus is herein named telfairia mosaic virus (TelMV).
• Leke, W. N., Mignouna, D. B., Brown, J. K., & Fondong, V. N. (2016). First report of Chayote yellow mosaic virus infecting bitter melon (Momordica charantia) exhibiting yellow mosaic symptoms in Benin, Nigeria, and Togo. Plant Disease, 100(Issue 5). doi:10.1094/pdis-11-15-1276-pdn
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  Bitter melon (Momordica charantia L.) is widely used as a traditional medicine for the treatment of diabetes in Asia (Fuangchan et al. 2011) and many other diseases in tropical Africa. Yellow mosaic symptoms, frequently associated with family Geminiviridae, genus Begomovirus, were observed in 60 to 80% of M. charantia plants in surveys conducted in three countries in West Africa. In August 2014, leaf samples were collected from three symptomatic and one nonsymptomatic M. charantia plants exhibiting yellow mosaic symptoms in Togo, Benin, and Nigeria (6°10.397′ N; 1°07.316′ E), (6°10.938′ N; 1°09.715′ E), and (7°29′57.5′ N; 3°54′11.3′ E), respectively. Leaves were press dried, and total DNA was extracted as described by Shepherd et al. 2008. The purified DNA from the four samples was separately pooled by country and the viral circular single-stranded DNA was enriched by rolling cycle amplification (RCA) (GE Healthcare Bio-Science, Piscataway, NJ). RCA products (Benin 57 (BN57), Nigeria 35 (NG35), and Togo 54 (TG54) were subjected to Illumina deep sequencing (MisEquation 2 × 150-bp configuration). Sequences were assembled using SeqMan NGen software (DNASTAR, Madison, WI). The assembled, apparently full-length begomoviral genome sequences obtained for all samples were 2,787 bp. BLASTn analysis revealed a closest match of the begomovirus Chayote yellow mosaic virus (ChaYMV) (AJ223191), reported from chayote plants Sechium edule (Jacq.) in Nigeria. Pairwise comparisons carried out using SDT software (Muhire et al. 2013) indicated that the bitter melon isolates (BN57, GenBank Accession No. KT454819; NG35, KT454825; and TG54, KT454820) shared 98 to 100% identity with each other, and 91% with ChaYMV (AJ223191). The genome of the ChaYMV isolates from bitter melon contained six open reading frames (ORFs), CP and V2 in the virion sense strand and Rep, C2, Ren, and C4 on the complimentary sense strand, similar to other previously characterized monopartite begomoviruses, thus suggesting that ChaYMV is a monopartite begomovirus and also because no B-component of a bipartite begomovirus was assembled from the bitter melon samples. No satellites were detected (alpha-and betasatellites). The primer pair ChaF 5′-CGACCCGCAGATATCATCA-3′ and ChaR 5′-ACCGAATCATAGAAATACATCCGTA-3′, designed based on an alignment of the CP gene sequences for the three isolates, was used to PCR-amplify the 758-bp CP gene from each sample, followed by cloning and DNA sequencing. Results indicated they shared 100% nt identity, and were 98 to 100% identical to the NGS assembled sequences. Phylogenetic analyses placed the bitter melon isolates together with AJ223191 (bootstrap value 100%). Based on the ICTV guidelines for species demarcation within the genus Begomovirus, at
• Malik, H. J., Raza, A., Amin, I., Scheffler, J. A., Scheffler, B. E., Brown, J. K., & Mansoor, S. (2016). RNAi-mediated mortality of the whitefly through transgenic expression of double-stranded RNA homologous to acetylcholinesterase and ecdysone receptor in tobacco plants. Scientific Reports, 6(Issue). doi:10.1038/srep38469
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  The whitefly Bemisia tabaci (Genn.) is a pest and vector of plant viruses to crop and ornamental plants worldwide. Using RNA interference (RNAi) to down regulate whitefly genes by expressing their homologous double stranded RNAs in plants has great potential for management of whiteflies to reduce plant virus disease spread. Using a Tobacco rattle virus-derived plasmid for in planta transient expression of double stranded RNA (dsRNA) homologous to the acetylcholinesterase (AChE) and ecdysone receptor (EcR) genes of B. tabaci, resulted in significant adult whitefly mortality. Nicotiana tabacum L. plants expressing dsRNA homologous to B. tabaci AChE and EcR were constructed by fusing sequences derived from both genes. Mortality of adult whiteflies exposed to dsRNA by feeding on N. tabacum plants, compared to non-dsRNA expressing plants, recorded at 24-hr intervals post-ingestion for three days, was >90% and 10%, respectively. Analysis of gene expression by real time quantitative PCR indicated that whitefly mortality was attributable to the down-regulation of both target genes by RNAi. Results indicated that knock down of whitefly genes involved in neuronal transmission and transcriptional activation of developmental genes, has potential as a bio-pesticide to reduce whitefly population size and thereby decrease virus spread.
• McRoberts, N., Thomas, C. S., Brown, J. K., Nutter, F. W., Stack, J. P., & Martyn, R. D. (2016). The evolution of a process for selecting and prioritizing plant diseases for recovery plans. Plant Disease, 100(Issue 4). doi:10.1094/pdis-04-15-0457-fe
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  One element of the cost of dealing with invasive species in the United States is the recovery from the arrival of exotic plant pathogens. We review the development of a process used to prioritize plant diseases for the federally mandated United State Department of Agriculture National Plant Disease Recovery System. A team of university, government, and industry scientists worked together over a 10-year period to develop a science-based objective approach to the challenge of effectively preparing for recovery plans from introduced pathogens, when the timing of the introduction of any single disease is unknown. Over time, the process transitioned from ad hoc, in which recovery plans were written when the relevant experts were able to do so, to a formally organized group-prioritization effort from which emerged the concept of generic recovery plan templates for groups of pathogens and diseases that have similar biological characteristics, and therefore, similar management approaches. Key characteristics for each template were determined through a multivariate analysis for 14 plant diseases for which a recovery plan already existed. The process was validated by a larger group of 15 plant pathologists, for which results were compared with those scored by 14 subject matter experts.
• Quintela, E. D., Abreu, A. G., Lima, J. F., Mascarin, G. M., Santos, J. B., & Brown, J. K. (2016). Reproduction of the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) B biotype in maize fields (Zea mays L.) in Brazil. Pest management science, 72(Issue 11). doi:10.1002/ps.4259
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  BACKGROUND: Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) was observed to have completed its reproductive cycle from the egg to the adult on maize (Zea mays L.). Field and screenhouse studies were carried out to investigate the durability of this putative and unprecedented adaptation to a grass host. RESULTS: Analysis of the mitochondrial COI gene sequence identified the maize-associated B. tabaci as the exotic B biotype (major clade North Africa-Mediterranean-Middle East). Results showed that whiteflies migrated from soybean crops and successfully established in maize plants. Females exhibited a preference for oviposition primarily on the first and second leaves of maize, but were also able to colonise developing leaves. A high, natural infestation on maize (193.3 individuals, all developmental stages) was observed within a 7.1 cm2 designated 'observation area'. Whiteflies collected from naturally infested maize leaves and allowed to oviposit on maize seedlings grown in a screenhouse developed from egg to adulthood in 28.6 ± 0.2 days. CONCLUSION: This is the first report of the B biotype completing its development on maize plants. This surprising anomaly indicates that the B biotype is capable of adapting to monocotyledonous host plants, and importantly, broadens the host range to include at least one species in the Poaceae. © 2016 Society of Chemical Industry.
• Brown, J. K. (2015). Asian citrus psyllid expression profiles suggest CLas-mediated alteration of adult nutrition and metabolism, and of nymphal development and immunity.. PLoS ONE, 10((6),), e0130328..
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  Vyas et al., Fisher, T., He, R., Nelson, W.H., Yin, G., Cicero, J.M., Willer, M., Kim, R., Kramer, R., May, G.A., Crow, J.A., Soderlund, C.A., Gang, D.R., and Brown, J.K. 2015. Asian citrus psyllid expression profiles suggest CLas-mediated alteration of adult nutrition and metabolism, and of nymphal development and immunity.
• Brown, J. K. (2015). First report of Chickpea chlorotic dwarf virus infecting tomato in Pakistan (Short report).. Plant Dis., 99:, 1287.
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  Zia-Ur-Rehman, M., Hameed, U., Herrmann, H-W, Iqbal, M.J., Haider, M.S., and Brown, J.K. 2015. First report of Chickpea chlorotic dwarf virus infecting tomato in Pakistan. Plant Dis. 99:1287. http://dx.doi.org/10.1094/PDIS-02-15-0202-PDN
• Brown, J. K. (2015). First report of begomoviruses infecting tomato with leaf curl disease in Burkina Faso (Short report). Plant Dis., 99:, 732.
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  Sattar, M.N., Koutou, M., Hosseini, S., Leke, W., Brown, J.K., and Kvarnheden, A. 2015. First report of begomoviruses infecting tomato with leaf curl disease in Burkina Faso. Plant Dis. 99: 732.
• Brown, J. K. (2015). First report of begomoviruses infecting tomato with leaf curl disease in Burkina Faso. (Short Report). Plant Disease, 99, 732.
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  Sattar, M.N., Koutou, M., Hosseini, S., Leke, W., Brown, J.K., and Kvarnheden, A. 2015. First report of begomoviruses infecting tomato with leaf curl disease in Burkina Faso. Plant Dis. 99: 732.
• Brown, J. K. (2015). Functional anatomy of the oral region of the potato psyllid (Hemiptera: Triozidae). Ann. Entomol. Soc. Am., 108:, 743-761.
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  Cicero, J. M., Stansly, P.A., and Brown, J.K. 2015. Functional anatomy of the oral region of the potato psyllid (Hemiptera: Triozidae). Ann. Entomol. Soc. Am. 108: 743-761.
• Brown, J. K. (2015). Revision of Begomovirus taxonomy based on pairwise sequence comparisons. Arch. Virol., 160:((6)), 1593-1619.
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  Brown, J.K., Zerbini, F.M., Navas-Castillo, J., Moriones, E., Ramos-Sobrinho, R., Silva, J.C.F., Briddon, R.W., Hernandez-Zepeda, C., Idris, A.M., Malathi, V.G., Martin, D.P., Rivera-Bustamante, R., Ueda, S., Varsani, A. 2015. Revision of Begomovirus taxonomy based on pairwise sequence comparisons. Arch. Virol. 160(6):1593-1619.
• Brown, J. K., Cicero, J. M., Crow, J. A., Fisher, T. W., Gang, D. R., He, R., Kim, R. W., Kramer, R., May, G. A., Nelson, W., Soderlund, C. A., Vyas, M., Willer, M. R., & Yin, G. (2015). Asian Citrus Psyllid Expression Profiles Suggest Candidatus Liberibacter Asiaticus-Mediated Alteration of Adult Nutrition and Metabolism, and of Nymphal Development and Immunity.. PloS one, 10(6), e0130328. doi:10.1371/journal.pone.0130328
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  The Asian citrus psyllid (ACP) Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is the insect vector of the fastidious bacterium Candidatus Liberibacter asiaticus (CLas), the causal agent of citrus greening disease, or Huanglongbing (HLB). The widespread invasiveness of the psyllid vector and HLB in citrus trees worldwide has underscored the need for non-traditional approaches to manage the disease. One tenable solution is through the deployment of RNA interference technology to silence protein-protein interactions essential for ACP-mediated CLas invasion and transmission. To identify psyllid interactor-bacterial effector combinations associated with psyllid-CLas interactions, cDNA libraries were constructed from CLas-infected and CLas-free ACP adults and nymphs, and analyzed for differential expression. Library assemblies comprised 24,039,255 reads and yielded 45,976 consensus contigs. They were annotated (UniProt), classified using Gene Ontology, and subjected to in silico expression analyses using the Transcriptome Computational Workbench (TCW) (http://www.sohomoptera.org/ACPPoP/). Functional-biological pathway interpretations were carried out using the Kyoto Encyclopedia of Genes and Genomes databases. Differentially expressed contigs in adults and/or nymphs represented genes and/or metabolic/pathogenesis pathways involved in adhesion, biofilm formation, development-related, immunity, nutrition, stress, and virulence. Notably, contigs involved in gene silencing and transposon-related responses were documented in a psyllid for the first time. This is the first comparative transcriptomic analysis of ACP adults and nymphs infected and uninfected with CLas. The results provide key initial insights into host-parasite interactions involving CLas effectors that contribute to invasion-virulence, and to host nutritional exploitation and immune-related responses that appear to be essential for successful ACP-mediated circulative, propagative CLas transmission.
• Brown, J. K., Zerbini, F. M., Navas-Castillo, J., Moriones, E., Ramos-Sobrinho, R., Silva, J. C., Fiallo-Olivé, E., Briddon, R. W., Hernández-Zepeda, C., Idris, A., Malathi, V. G., Martin, D. P., Rivera-Bustamante, R., Ueda, S., & Varsani, A. (2015). Revision of Begomovirus taxonomy based on pairwise sequence comparisons. Archives of virology, 160(Issue 6). doi:10.1007/s00705-015-2398-y
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  Viruses of the genus Begomovirus (family Geminiviridae) are emergent pathogens of crops throughout the tropical and subtropical regions of the world. By virtue of having a small DNA genome that is easily cloned, and due to the recent innovations in cloning and low-cost sequencing, there has been a dramatic increase in the number of available begomovirus genome sequences. Even so, most of the available sequences have been obtained from cultivated plants and are likely a small and phylogenetically unrepresentative sample of begomovirus diversity, a factor constraining taxonomic decisions such as the establishment of operationally useful species demarcation criteria. In addition, problems in assigning new viruses to established species have highlighted shortcomings in the previously recommended mechanism of species demarcation. Based on the analysis of 3,123 full-length begomovirus genome (or DNA-A component) sequences available in public databases as of December 2012, a set of revised guidelines for the classification and nomenclature of begomoviruses are proposed. The guidelines primarily consider a) genus-level biological characteristics and b) results obtained using a standardized classification tool, Sequence Demarcation Tool, which performs pairwise sequence alignments and identity calculations. These guidelines are consistent with the recently published recommendations for the genera Mastrevirus and Curtovirus of the family Geminiviridae. Genome-wide pairwise identities of 91 % and 94 % are proposed as the demarcation threshold for begomoviruses belonging to different species and strains, respectively. Procedures and guidelines are outlined for resolving conflicts that may arise when assigning species and strains to categories wherever the pairwise identity falls on or very near the demarcation threshold value.
• Cicero, J. M., Stansly, P. A., & Brown, J. K. (2015). Functional anatomy of the oral region of the potato psyllid (Hemiptera: Psylloidea: Triozidae). Annals of the Entomological Society of America, 108(Issue 5). doi:10.1093/aesa/sav059
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  "Candidatus Liberibacter solanacearum", causal agent of zebra chip of potato and veingreening of tomato, is prolific in tissues of the oral region of its vector, Bactericera cockerelli (Sulc). The region has, evolutionarily, reflexed under the head ("opisthognathy"), so that the mandibular stylets are ventral to the maxillary stylets, and both are directed posteriorly. The region includes the labium, furcasternum, and tentorium. The tentorium is a minute, crate-shaped, extremely complex endoskeletal apparatus consisting of preoral and postoral sections, with the primitive mouth in between. Except for certain prominent structures, its functional anatomy is poorly understood, and provisional (generic) terminology is needed to identify them. It is formed from several panel-shaped and rod-shaped invaginations of the preoral orifice. Panels divide the preoral section into four tissue blocks: hypopharynx, epipharynx, and two lateral blocks of questionable homological identity. Those between the hypopharynx and lateral blocks are fluted into "holsters." Holsters are extended into the postoral section as "loading sleeves." Together, both house the stylets. Stylet manipulation muscles are attached to them, not to the stylets themselves. Loading sleeves also function to guide presumptive stylets into their functional positions during a molt. Rods are located in the postoral section, and they form "ecdysial gaps" which also assist in molting. Stylets converge toward the preoral orifice, designed to interlock the maxillars and redirect the mandibulars to their flanks to form a "stylet bundle," and rotate the bundle 90° so that it can curve, about its most-bendable axis, into a cuticular pouch or "crumena" on exit.
• Mignouna, D. B., Leke, W. N., Kvarnheden, A., & Brown, J. K. (2015). Begomovirus disease complex: emerging threat to vegetable production systems of West and Central Africa. Agricultural and Food Science, 4(1), 1-14. doi:10.1186/s40066-014-0020-2
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  Vegetables play a major role in the livelihoods of the rural poor in Africa. Among major constraints to vegetable production worldwide are diseases caused by a group of viruses belonging to the genus Begomovirus, family Geminiviridae. Begomoviruses are plant-infecting viruses, which are transmitted by the whitefly vector Bemisia tabaci and have been known to cause extreme yield reduction in a number of economically important vegetables around the world. Several begomoviruses have been detected infecting vegetable crops in West and Central Africa (WCA). Small single stranded circular molecules, alphasatellites and betasatellites, which are about half the size of their helper begomovirus genome, have also been detected in plants infected by begomoviruses. In WCA, B. tabaci has been associated with suspected begomovirus infections in many vegetable crops and weed species. Sequencing of viral genomes from crops such as okra resulted in the identification of two previously known begomovirus species (Cotton leaf curl Gezira virus and Okra yellow crinkle virus) as well as a new recombinant begomovirus species (Okra leaf curl Cameroon virus), a betasatellite (Cotton leaf curl Gezira betasatellite) and new alphasatellites. Tomato and pepper plants with leaf curling were shown to contain isolates of new begomoviruses, collectively referred to as West African tomato-infecting begomoviruses (WATIBs), new alphasatellites and betasatellites. To study the potential of weeds serving as begomovirus reservoirs, begomoviruses and satellites in the weed Ageratum conyzoides were characterized. Sequence analyses showed that they were infected by isolates of a new begomovirus (Ageratum leaf curl Cameroon virus) that belong to the WATIBs group, a new betasatellite (Ageratum leaf curl Cameroon betasatellite), an alphasatellite and two types of defective recombinants between a begomovirus and an alphasatellite. Putative recombinations were detected in begomovirus genomes for all four plant species studied, indicating that recombination is an important mechanism for their evolution. A close relationship between the begomoviruses infecting pepper and tomato and A. conyzoides and the detection of the same alphasatellite in them support the idea that weeds are important reservoirs for begomoviruses and their satellites. With this high diversity, recombination potential and transmission by B. tabaci, begomoviruses and ssDNA satellites pose a serious threat to crop production in West and Central Africa.
• Sattar, M. N., Koutou, M., Hosseini, S., Leke, W. N., Brown, J. K., & Kvarnheden, A. (2015). First identification of begomoviruses infecting tomato with leaf curl disease in Burkina Faso. Plant Disease, 99(Issue 5). doi:10.1094/pdis-08-14-0837-pdn
• Zia-Ur-Rehman, M., Hameed, U., Herrmann, H. W., Iqbal, M. J., Haider, M. S., & Brown, J. K. (2015). First report of chickpea chlorotic dwarf virus infecting tomato crops in Pakistan. Plant Disease, 99(Issue 9). doi:10.1094/pdis-02-15-0202-pdn
• Al-Saleh, M. A., Ahmad, M. H., Al-Shahwan, I. M., Brown, J. K., & Idris, A. M. (2014). First report of Watermelon chlorotic stunt virus infecting watermelon in Saudi Arabia. Plant Disease, 98(Issue 10). doi:10.1094/pdis-06-14-0583-pdn
• Al-Saleh, M. A., Al-Shahwan, I. M., Brown, J. K., & Idris, A. M. (2014). Molecular characterization of a naturally occurring intraspecific recombinant begomovirus with close relatives widespread in southern Arabia. Virology Journal, 11(Issue 1). doi:10.1186/1743-422x-11-103
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  Background: Tomato leaf curl Sudan virus (ToLCSDV) is a single-stranded DNA begomovirus of tomato that causes downward leaf curl, yellowing, and stunting. Leaf curl disease results in significant yield reduction in tomato crops in the Nile Basin. ToLCSDV symptoms resemble those caused by Tomato yellow leaf curl virus, a distinct and widespread begomovirus originating in the Middle East. In this study, tomato samples exhibiting leaf curl symptoms were collected from Gezira, Sudan. The associated viral genome was molecularly characterized, analyzed phylogenetically, and an infectious clone for one isolate was constructed. Findings. The complete genomes for five newly discovered variants of ToLCSDV, ranging in size from 2765 to 2767-bp, were cloned and sequenced, and subjected to pairwise and phylogenetic analyses. Pairwise analysis indicated that the five Gezira isolates shared 97-100% nucleotide identity with each other. Further, these variants of ToLCSDV shared their highest nucleotide identity at 96-98%, 91-95%, 91-92%, and 91-92% with the Shambat, Gezira, Oman and Yemen strains of ToLCSDV, respectively. Based on the high maximum nucleotide identities shared between these ToLCSDV variants from Gezira and other previously recognized members of this taxonomic group, they are considered isolates of the Shambat strain of ToLCSDV. Analysis of the complete genome sequence for these new variants revealed that they were naturally occurring recombinants between two previously reported strains of ToLCSDV. Finally, a dimeric clone constructed from one representative ToLCSV genome from Gezira was shown to be infectious following inoculation to tomato and N. benthamiana plants. Conclusion: Five new, naturally occurring recombinant begomovirus variants (>96% shared nt identity) were identified in tomato plants from Gezira in Sudan, and shown to be isolates of the Shambat strain of ToLCSDV. The cloned viral genome was infectious in N. benthamiana and tomato plants, and symptoms in tomato closely resembled those observed in field infected tomato plants, indicating the virus is the causal agent of the leaf curl disease. The symptoms that developed in tomato seedlings closely resembled those observed in field infected tomato plants, indicating that ToLCSDV is the causal agent of the leaf curl disease in Gezira. © 2014 Al-Saleh et al.; licensee BioMed Central Ltd.
• Angelova, A., Park, S. H., Kyndt, J., Fitzsimmons, K., & Brown, J. K. (2014). Sonication-based isolation and enrichment of Chlorella protothecoides chloroplasts for Illumina genome sequencing. Journal of Applied Phycology, 26(Issue 1). doi:10.1007/s10811-013-0125-1
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  With the increasing world demand for biofuel, a number of oleaginous algal species are being considered as renewable sources of oil. Chlorella protothecoides Krüger synthesizes triacylglycerols (TAGs) as storage compounds that can be converted into renewable fuel utilizing an anabolic pathway that is poorly understood. The paucity of algal chloroplast genome sequences has been an important constraint to chloroplast transformation and for studying gene expression in TAGs pathways. In this study, the intact chloroplasts were released from algal cells using sonication followed by sucrose gradient centrifugation, resulting in a 2.36-fold enrichment of chloroplasts from C. protothecoides, based on qPCR analysis. The C. protothecoides chloroplast genome (cpDNA) was determined using the Illumina HiSeq 2000 sequencing platform and found to be 84,576 Kb in size (8.57 Kb) in size, with a GC content of 30.8 %. This is the first report of an optimized protocol that uses a sonication step, followed by sucrose gradient centrifugation, to release and enrich intact chloroplasts from a microalga (C. prototheocoides) of sufficient quality to permit chloroplast genome sequencing with high coverage, while minimizing nuclear genome contamination. The approach is expected to guide chloroplast isolation from other oleaginous algal species for a variety of uses that benefit from enrichment of chloroplasts, ranging from biochemical analysis to genomics studies. © 2013 Springer Science+Business Media Dordrecht.
• Brown, J. K. (2014). Comparative transcriptomic profiles of potato and Asian citrus psyllid adults and nymphs: vector interactor-CLas effector mediation of circulative- propagative transmission.. Pathogens, 3, 875-907.
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  Fisher, T.W., Vyas, M., He, R., Cicero, J., Nelson, W., Willer, M., Kim, R., Kramer, R., May, G.A., Crow, J.A., Soderlund, C.A., Gang, D.R., Brown, J.K. 2014. Comparative transcriptomic profiles of potato and Asian citrus psyllid adults and nymphs: vector interactor-CLas effector mediation of circulative- propagative transmission. Pathogens 3: 875-907.
• Brown, J. K. (2014). Diversification of penaeid shrimp infectious myonecrosis virus in Indonesia.. Virus Res., 189, 97-105.
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  Naim, S., Brown, J.K., and Nibert, M.L. 2014. Diversification of penaeid shrimp infectious myonecrosis virus in Indonesia. Virus Res. 189: 97-105.
• Brown, J. K. (2014). Establishment of three new genera in the family Geminiviridae: Becurtovirus, Eragrovirus and Turncurtovirus. Arch. Virol. (accepted).. Archives of Virology, 159, 2193-2203.
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  Varsani, A., Navas-Castillo, J., Moriones, E., Hernández-Zepeda, C., Idris, A.M., Brown, J.K., Zerbini, F. M., Martin, D.P. 2014. Establishment of three new genera in the family Geminiviridae: Becurtovirus, Eragrovirus and Turncurtovirus. Arch. Virol. 159: 2193-2203.
• Brown, J. K. (2014). First record of Jack Beardsley mealybug, Pseudococcus jackbeardsleyi (Hemiptera: Pseudococcidae), from Africa.. Flor. Entomol. Soc., 97, 1690-1693.
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  N’Guessan, P.W., Watson, G.W., Brown, J.K., N'Guessan, F.K. 2014. First record of Jack Beardsley mealybug, Pseudococcus jackbeardsleyi (Hemiptera: Pseudococcidae), from Africa. Flor. Entomol. Soc. 97:1690-1693.
• Brown, J. K. (2014). First report of Watermelon chlorotic stunt virus infecting watermelon in Saudi Arabia. Plant Disease (Short report), 98, 1451.
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  Al-Saleh, M.A.M., Ahmad, M.H., Brown, J.K., and Idris, A.M. 2014. First report of Watermelon chlorotic stunt virus infecting watermelon in Saudi Arabia. Plant Dis. 98:1451.
• Brown, J. K. (2014). First report of the leaf curl complex: Mesta yellow vein mosaic virus, Cotton leaf curl Multan betasatellite, and Cotton leaf curl Burewala alphasatellite infecting cotton in Pakistan.. Plant Disease (Short report), 98, 1447.
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  Hameed, U., Ur-Rehman, Z., Herrmann, H.W., Haider, M.S. and Brown, J.K. 2014. First report of Okra enation leaf curl virus and associated Cotton leaf curl Multan betasatellite and Cotton leaf curl Multan alphasatellite infecting cotton in Pakistan: A new member of the cotton leaf curl disease complex. Plant Dis. 98:1447.
• Brown, J. K. (2014). Identification and molecular characterization of two begomoviruses from Pouzolzia zeylanica (L.) Benn. exhibiting yellow mosaic symptoms in adjacent regions of China and Vietnam.. Archives of Virology, 159, 2799-2803.
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  Tang, Y.F., Du, Z.G., He, Z.F., Brown, J.K., and She, X.M. 2014. Identification and molecular characterization of two begomoviruses from Pouzol. zeylanica (L.) Benn. exhibiting yellow mosaic symptoms in adjacent regions of China and Vietnam. Arch. Virol. 159:2799-2803.
• Brown, J. K. (2014). Introduction of Cotton leaf curl Gezira virus into the United Arab Emirates.. Plant Disease (Short report), 98, 1593.
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  Idris, A.M., Al-Saleh, M.A.M., Amer, M., Abdalla, O., Al-Shahwan, I.M., and J.K.Brown. 2014. Introduction of Cotton leaf curl Gezira virus into the United Arab Emirates. Plant Dis. 98:1593.
• Brown, J. K. (2014). Isolation and characterization of nine microsatellite locifrom the sweetpotato whitefly Bemisia tabaci biotype B. J. Insect Sci., 14, 148.
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  Hadjistylli, M., Schwartz, S.A., Brown, J.K., and Roderick, G.K. 2014. Isolation and characterization of nine microsatellite locifrom the sweetpotato whitefly Bemisia tabaci biotype B. J. Insect Sci. 14: 148. doi: 10.1093/jisesa/ieu010.
• Brown, J. K. (2014). Microarray analysis of tomato plants exposed to the non-viruliferous or viruliferous whitefly vector harboring Pepper golden mosaic virus. J Insect Science, 14(doi: 10.1093/jisesa/ieu092.), 230.
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  Musser, R. O., Hum-Musser, S.M., Gallucci, M., Des Rochers, B.1, and Brown, J.K. 2014. Microarray analysis of tomato plants exposed to the non-viruliferous or viruliferous whitefly vector harboring Pepper golden mosaic virus. J. Insect Sci. 14: (230) doi: 10.1093/jisesa/ieu092.
• Brown, J. K. (2014). Molecular characterization of a naturally occurring intraspecific recombinant begomovirus with close relatives widespread in southern Arabia. Virology Journal, 11, 103.
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  Al-Saleh, M.A., Al-Shahwan, I.M., Brown, J.K., and Idris, A.M. 2014. Molecular characterization of a naturally occurring intraspecific recombinant begomovirus with close relatives widespread in southern Arabia. Virology Journal 11:103 doi:10.1186/1743-422X-11-103.
• Brown, J. K. (2014). Population structure of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood), an invasive species from the Americas, 60 years after invading China. Int. J. Mol. Sci., 15, 13514-13528.
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  Gao, R.R., Zhang, W.P., Zhang, R.M., Zhou, H.X., Pan, H.P., Zhang, Y.J., Brown, J.K., and Chu, D. 2014. Population structure of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood), an invasive species from the Americas, 60 years after invading China. Int. J. Mol. Sci. 15:13514-13528. doi:10.3390/ijms150813514.
• Brown, J. K. (2014). Revisiting the classification of curtoviruses based on genome-wide pairwise identity.. Archives of Virology, 159, 1873-1882.
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  Varsani, A., Martin, D.P., Navas-Castillo, J., Moriones, E., Hernández-Zepeda, C., Idris, A.M., Murilo, F., Zerbini, F.M., and Brown, J.K. 2014. Revisiting the classification of curtoviruses based on genome-wide pairwise identity. Arch. Virol. 159: 1873-1882.
• Brown, J. K., & Idris, A. M. (2014). Viral metagenomics: validation of genome enrichment coupled with Next Generation Sequencing reveals reproducibility between laboratory and field samples, and reveals polymorphisms in begomovirus populations from natural plant infections. Viruses, 6, 1219-1236.
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  Idris, A., Al-Saleh, M., Piatek, M.J., Al-Shahwan, I., Ali, S., and Brown, J.K. 2014. Viral metagenomics: validation of genome enrichment coupled with Next Generation Sequencing reveals reproducibility between laboratory and field samples, and reveals polymorphisms in begomovirus populations from natural plant infections. Viruses 6:1219-1236; doi:10.3390/v6031219
• Fisher, T. W., Vyas, M., He, R., Nelson, W., Cicero, J. M., Willer, M., Kim, R., Kramer, R., May, G. A., Crow, J. A., Soderlund, C. A., Gang, D. R., & Brown, J. K. (2014). Comparison of potato and Asian citrus psyllid adult and nymph transcriptomes identified vector transcripts with potential involvement in circulative, propagative liberibacter transmission. Pathogens, 3(Issue 4). doi:10.3390/pathogens3040875
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  The potato psyllid (PoP) Bactericera cockerelli (Sulc) and Asian citrus psyllid (ACP) Diaphorina citri Kuwayama are the insect vectors of the fastidious plant pathogen, Candidatus Liberibacter solanacearum (CLso) and Ca. L. asiaticus (CLas), respectively. CLso causes Zebra chip disease of potato and vein-greening in solanaceous species, whereas, CLas causes citrus greening disease. The reliance on insecticides for vector management to reduce pathogen transmission has increased interest in alternative approaches, including RNA interference to abate expression of genes essential for psyllid-mediated Ca. Liberibacter transmission. To identify genes with significantly altered expression at different life stages and conditions of CLso/CLas infection, cDNA libraries were constructed for CLso-infected and -uninfected PoP adults and nymphal instars. Illumina sequencing produced 199,081,451 reads that were assembled into 82,224 unique transcripts. PoP and the analogous transcripts from ACP adult and nymphs reported elsewhere were annotated, organized into functional gene groups using the Gene Ontology classification system, and analyzed for differential in silico expression. Expression profiles revealed vector life stage differences and differential gene expression associated with Liberibacter infection of the psyllid host, including invasion, immune system modulation, nutrition, and development.
• Gao, R. R., Zhang, W. P., Wu, H. T., Zhang, R. M., Zhou, H. X., Pan, H. P., Zhang, Y. J., Brown, J. K., & Chu, D. (2014). Population structure of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood), an invasive species from the Americas, 60 years after invading China. International Journal of Molecular Sciences, 15(Issue 8). doi:10.3390/ijms150813514
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  Though the greenhouse whitefly, Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae) was introduced into China more than 60 years ago, the genetic diversity and structure of this exotic insect pest and virus vector have not been studied. To investigate the population genetic characteristics of this invasive species and to identify potential invasion routes, the genetic diversity and population structure of 17 collections of T. vaporariorum from nine provinces in China were analyzed using seven microsatellite loci. The results of the analyses indicated that the genetic diversity for the populations examined from the four provinces: Jilin, Ningxia, Guizhou and Qinghai, was lower than the genetic diversity of populations from the five provinces: Yunnan, Shandong, Shanxi, Liaoning, and Gansu. The T. vaporariorum populations analyzed in this study grouped as two distinct genetic clusters based on the analysis using STRUCTURE, whereas, 8 clusters were identified based on the BAPS analysis. Of the 136 genetic distance (Fst) values, 128 (94%) were associated with a significant exact test. However, there was no significant relationship between Fst and geographical distance. These results demonstrate that populations of T. vaporariorum in China exhibit significant genetic differentiation, indicating the likelihood that multiple introductions of T. vaporarioruminto China have occurred. Also, the populations collected from the provinces of Jilin, Ningxia, Guizhou and Qinghai appear to represent secondary introductions originating from other Chinese provinces. © 2014 by the authors; licensee MDPI, Basel, Switzerland.
• Hadjistylli, M., Roderick, G. K., & Schwartz, S. A. (2013). Isolation and characterization of 9 microsatellite locifrom the sweetpotato whitefly Bemisia tabaci biotype B.. Insect Science.
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  Hadjistylli, M., SA.Schwartz, JK. Brown, and GK. Roderick. 2014. Isolation and characterization of nine microsatellite loci from the sweetpotato whitefly Bemisia tabaci biotype B. Insect Science (accepted).
• Hadjistylli, M., Schwartz, S. A., Brown, J. K., & Roderick, G. K. (2014). Isolation and characterization of nine microsatellite loci from bemisia tabaci (Hemiptera: Aleyrodidae) Biotype B. Journal of Insect Science, 14(Issue). doi:10.1093/jisesa/ieu010
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  Nine microsatellites were isolated from Bemisia tabaci (Gennadius) biotype B and screened across 60 individuals from two populations (biotype B) to examine polymorphism. Two to 12 alleles were observed per locus. Observed and expected heterozygosities ranged from 0.033 to 0.967 and 0.033 to 0.854, respectively. There was no significant deviation from Hardy-Weinberg equilibrium and no significant linkage disequilibrium between loci. One locus showed evidence for null alleles. These loci will be useful in future studies of the genetic structure of worldwide biotypes and gene flow analyses between and within biotypes of B. tabaci.
• Hameed, U., Zia-Ur-Rehman, M., Herrmann, H. W., Haider, M. S., & Brown, J. K. (2014). First report of okra enation leaf curl virus and associated cotton leaf curl Multan betasatellite and Cotton leaf curl Multan alphasatellite infecting cotton in Pakistan: A new member of the cotton leaf curl disease complex. Plant Disease, 98(Issue 10). doi:10.1094/pdis-04-14-0345-pdn
• He, R., Nelson, W., Willer, M. R., Soderlund, C., Brown, J. K., Vyas, M., Gang, D., & Fisher, T. (2014). A Comparative Transcriptomic Approach to Elucidate Psyllid-Ca. Liberibacter Interactions. Journal of Citrus Pathology, 1(1).
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  Citrus greening is the most destructive disease of citrus crops worldwide. The introduced Asian citrus psyllid (ACP) Diaphorina citri Kuwayama transmits the (putative) causal bacterium, Candidatus Liberibacter asiaticus. A close relative, Ca. L. solanacearum, is the pathogen associated with Zebra chip disease of potato and vein-greening disease of tomato. It is both transmitted by and propagative in the endemic (western U.S) potato psyllid (PoP) Bactericerca cockerelli Sulc. The PoP occurs widely in the western U.S. and so has been used as a parallel study system for the quarantined ACP-greening complex. To identify proteins involved in global psyllid-Ca. Liberibacter interactions, the ACP and PoP transcriptomes were sequenced, yielding a total of 45,976 and 82,224 Illumina unique ACP and PoP transcripts, respectively. Cluster analysis revealed a high degree of sequence and transcript conservation suggestive of roles in core growth and developmental processes, providing the first molecular snapshot of the specific psyllid genes responsive to parasite invasion and circulation in the host. Evidence of inter-psyllid molecular conservation substantiates the suitability of PoP as a study system for ACP-Ca. L. asiatcus. Comparative in silico expression analysis within and between psyllid species revealed predicted functions involved in Ca. Liberibacter parasitism that were both unique and shared in common among adult and nymphal instars. In addition, functional characterization based on Gene Ontology analysis has revealed a number of genes associated with host-parasite interactions that could mediate Ca. Liberibacter infection, propagation, and circulation in the psyllid, as well as transmission processes.
• He, R., Nelson, W., Willer, M. R., Soderlund, C., Brown, J. K., Vyas, M., Gang, D., Fisher, T., & Cicero, J. (2014). Translating Anatomical Structures and Functional Genomics of Candidatus Liberibacter asiaticus and solanacearum Into Circulative, Propagative Vector-Mediated Transmission Processes. Journal of Citrus Pathology, 1(1).
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  Author(s): Fisher, T.; Cicero, J.; Vyas, M.; He, R.; Nelson, W.; Willer, M.; Soderlund, C.; Gang, D.; Brown, J. K. | Abstract: Ca. Liberibacter asiaticus is the putative fastidious bacterial causal agent of citrus greening disease, also known as Huanglongbing (HLB), translated from Chinese as yellow dragon disease. The HLB bacterial pathogen is indigenous to Asia but has been introduced and dispersed to citrus throughout the Americas. A related bacterium that is indigenous to the Americas causes damage to potato (zebra chip) and tomato (vein-greening) and other solanaceous hosts. The causal agents are propagative and circulative in the psyllid vector, Diaphorina citri (Kuwayama) and Bactericera cockerelli (Sulc.), the Asian citrus and potato (or tomato) psyllid, respectively. The specific psyllid proteins that are indirectly or directly involved in the circulative, propagative transmission pathway are not known. However, if proteins were known that function at key points in the pathway e.g. post-ingestion, infection, biofilm formation, nutrition, circulation, and/or acquisition were known, such knowledge could be exploited to knock out their expression and abate pathogen transmission. To this end a combined approach involving functional genomics and anatomical localization of the bacterium is being implemented. Results indicate that Ca. Liberibacter establishes biofilms on the outer surfaces of the alimentary canal and salivary glands of the Asian citrus psyllid (ACP) Diaphorina citri Kuwayama and the potato psyllid (PP) Bactericera cockerelli Sulc. In silico transcript profiling of infected and uninfected ACP and PP identified a number of mis-expressed, unique transcripts (unitrans). Functional predictions (gene ontology associations) implicate certain of these unitrans in Ca. Liberibacter infection of the psyllid host and/or in psyllid-mediated Ca. Liberibacter transmission processes.
• Hosseinzadeh, M. R., Hosseinzadeh, M. R., Shams-Bakhsh, M., Shams-Bakhsh, M., Osaloo, S. K., Osaloo, S. K., Brown, J. K., & Brown, J. K. (2014). Phylogenetic relationships, recombination analysis, and genetic variability among diverse variants of tomato yellow leaf curl virus in Iran and the Arabian Peninsula: Further support for a TYLCV center of diversity. Archives of Virology, 159(3), 485-497.
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  Hosseinzadeh, M.R., Shamsbakhsh, M., Kazempour Osalou, S., and Brown, J.K. 2014. Phylogenetic relationships, recombination analysis, and genetic variability among diverse variants of Tomato yellow leaf curl virus in Iran and the Arabian Peninsula: further support for a TYLCV-center of diversity. Arch. Virol.158: 485-497 DOI 10.1007/s00705-013-1851-z.
• Hosseinzadeh, M. R., Shams-Bakhsh, M., Osaloo, S. K., & Brown, J. K. (2014). Phylogenetic relationships, recombination analysis, and genetic variability among diverse variants of tomato yellow leaf curl virus in Iran and the Arabian Peninsula: Further support for a TYLCV center of diversity. Archives of Virology, 159(Issue 3). doi:10.1007/s00705-013-1851-z
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  The discovery of five strains of TYLCV in Iran, including the most well-known and widespread, TYLCV-IL, spurred a detailed study of the full-length genomes of additional TYLCV field isolates and an in-depth analysis of phylogenetic relationships, extent of recombination, and genetic variability of TYLCV isolates within Iran and throughout the Arabian Peninsula. Phylogenetic analysis of complete genome sequences of TYLCV isolates from Iran and other countries revealed four monophyletic clusters could be differentiated based on geographical origin, indicating that recent dispersal of these populations (by the vector or by humans) from these four regions has occurred minimally, or not at all. Genetic analysis revealed that TYLCV-IL isolates from southern Iran possessed greater genetic variability than the northeastern isolates, a pattern that may be reflective of evolution driven by geographically dependent isolation. Similarly, isolates of TYLCV-OM originating from Oman showed greater genetic variability than TYLCV-OM variants from Iran. Major recombination events, which were detected in all strains of TYLCV had breakpoints initiating in the C1, C1/C4, C2/C3 and V1 open reading frames (ORFs) and ending at the non-coding region and the C1, C1/C2 and C3 ORFs. Hence, these regions have consistently served as hot spots for recombination worldwide during the evolution of all currently recognized isolates and strains of TYLCV. © 2013 Springer-Verlag Wien.
• Musser, R. O., Hum-Musser, S. M., Gallucci, M., DesRochers, B., & Brown, J. K. (2014). Microarray analysis of tomato plants exposed to the nonviruliferous or viruliferous whitefly vector harboring pepper golden mosaic virus. Journal of Insect Science, 14(Issue 1). doi:10.1093/jisesa/ieu092
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  Plants are routinely exposed to biotic and abiotic stresses to which they have evolved by synthesizing constitutive and induced defense compounds. Induced defense compounds are usually made, initially, at low levels; however, following further stimulation by specific kinds of biotic and abiotic stresses, they can be synthesized in relatively large amounts to abate the particular stress. cDNA microarray hybridization was used to identify an array of genes that were differentially expressed in tomato plants 15 d after they were exposed to feeding by nonviruliferous whiteflies or by viruliferous whiteflies carrying Pepper golden mosaic virus (PepGMV) (Begomovirus, Geminiviridae). Tomato plants inoculated by viruliferous whiteflies developed symptoms characteristic of PepGMV, whereas plants exposed to nonviruliferous whitefly feeding or nonwounded (negative) control plants exhibited no disease symptoms. The microarray analysis yielded over 290 spotted probes, with significantly altered expression of 161 putative annotated gene targets, and 129 spotted probes of unknown identities. The majority of the differentially regulated "known" genes were associated with the plants exposed to viruliferous compared with nonviruliferous whitefly feeding. Overall, significant differences in gene expression were represented by major physiological functions including defense-, pathogen-, photosynthesis-, and signaling-related responses and were similar to genes identified for other insect-plant systems. Viruliferous whitefly-stimulated gene expression was validated by real-Time quantitative polymerase chain reaction of selected, representative candidate genes (messenger RNA): Arginase, dehydrin, pathogenesis-related proteins 1 and-4, polyphenol oxidase, and several protease inhibitors. This is the first comparative profiling of the expression of tomato plants portraying different responses to biotic stress induced by viruliferous whitefly feeding (with resultant virus infection) compared with whitefly feeding only and negative control nonwounded plants exposed to neither. These results may be applicable to many other plant-insect-pathogen system interactions.
• N'Guessan, P. W., Watson, G. W., Brown, J. K., & N'guessan, F. K. (2014). First record of Pseudococcus jackbeardsleyi (Hemiptera: Pseudococcidae) from Africa, côte d'Ivoire. Florida Entomologist, 97(Issue 4). doi:10.1653/024.097.0443
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  Cocoa swollen shoot virus disease is an important virus disease of cocoa occurring mainly in West Africa. Mealybugs are known to be vectors of the pathogen, Cacao swollen shoot virus. Since recent outbreaks in Côte d'Ivoire, studies have been undertaken on different aspects of the disease. During 2013, surveys were conducted to identify mealybug species infesting aerial parts of cocoa (Theobroma cacao L.; Malvales: Malvaceae) trees at various sites and the samples were authoritatively identified using morphological characters. A species new to Africa, Pseudococcus jackbeardsleyi Gimpel & Miller (Hemiptera: Pseudococcidae), was found at 2 localities in Côte d'Ivoire, i.e., Buyo (Soubré county) and Gbalékro (Agboville county). Hosts of this polyphagous mealybug belong to 47 plant families and include banana, eggplant, Hibiscus spp., potato, sweet pepper and tomato. Virus transmission by P. jackbeardsleyi has not been recorded, but it belongs to the same genus as P. maritimus (Ehrhorn), which transmits Little cherry virus 2 to sweet cherry, and P. longispinus (Targioni Tozzetti), which transmits Grapevine A trichovirus (GAV) to grapevine and Cacao swollen shoot virus (CSSV) to cocoa. The introduction and establishment of P. jackbeardsleyi in Africa may have a considerable impact on both commercial and subsistence agriculture.
• Naim, S., Brown, J. K., & Nibert, M. L. (2014). Genetic diversification of penaeid shrimp infectious myonecrosis virus between Indonesia and Brazil. Virus Research, 189(Issue). doi:10.1016/j.virusres.2014.05.013
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  Infectious myonecrosis virus (IMNV) is a pathogen of penaeid shrimp, most notably the whiteleg shrimp Litopenaeus vannamei. First discovered in L. vannamei from Brazilian aquaculture farms in 2003, IMNV was additionally confirmed in L. vannamei from Indonesian farms in 2006 and has since been found in numerous provinces there. Only two complete sequences of IMNV strains have been reported to date, one strain from the Brazilian state of Piauí collected in 2003 and another from the Indonesian province of East Java collected in 2006. In this study, we determined the complete sequences of two additional Indonesian strains, one from Lampung province collected in 2011 and another from East Java province collected in 2012. We also determined partial sequences for six other strains to enhance phylogenetic comparisons, which have heretofore been limited by the small number of reported sequences, including only one for an Indonesian strain. The new results demonstrate clear genetic diversification of IMNV between Indonesia and Brazil, as well as within Indonesia. Analyses of conserved sequence motifs suggest a revised RNA pseudoknot prediction for ribosomal frameshifting. © 2014 Elsevier B.V.
• Piatek, M. J., Idris, A. M., Brown, J. K., Ali, S., Al-shahwan, I. M., & Al-saleh, M. A. (2014). Viral metagenomics: analysis of begomoviruses by illumina high-throughput sequencing.. Viruses, 6(3), 1219-36. doi:10.3390/v6031219
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  Traditional DNA sequencing methods are inefficient, lack the ability to discern the least abundant viral sequences, and ineffective for determining the extent of variability in viral populations. Here, populations of single-stranded DNA plant begomoviral genomes and their associated beta- and alpha-satellite molecules (virus-satellite complexes) (genus, Begomovirus; family, Geminiviridae) were enriched from total nucleic acids isolated from symptomatic, field-infected plants, using rolling circle amplification (RCA). Enriched virus-satellite complexes were subjected to Illumina-Next Generation Sequencing (NGS). CASAVA and SeqMan NGen programs were implemented, respectively, for quality control and for de novo and reference-guided contig assembly of viral-satellite sequences. The authenticity of the begomoviral sequences, and the reproducibility of the Illumina-NGS approach for begomoviral deep sequencing projects, were validated by comparing NGS results with those obtained using traditional molecular cloning and Sanger sequencing of viral components and satellite DNAs, also enriched by RCA or amplified by polymerase chain reaction. As the use of NGS approaches, together with advances in software development, make possible deep sequence coverage at a lower cost; the approach described herein will streamline the exploration of begomovirus diversity and population structure from naturally infected plants, irrespective of viral abundance. This is the first report of the implementation of Illumina-NGS to explore the diversity and identify begomoviral-satellite SNPs directly from plants naturally-infected with begomoviruses under field conditions.
• Tang, Y. F., Du, Z. G., He, Z. F., Brown, J. K., & She, X. M. (2014). Identification and molecular characterization of two begomoviruses from Pouzolzia zeylanica (L.) Benn. exhibiting yellow mosaic symptoms in adjacent regions of China and Vietnam. Archives of Virology, 159(Issue 10). doi:10.1007/s00705-014-2049-8
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  Two monopartite begomoviruses were isolated from Pouzolzia zeylanica (L.) Benn. plants showing yellow mosaic symptoms in Gaoyao, Guangdong Province, China (GD1) and in Phu Tho, Vietnam (VN), respectively. A comparison of the complete genome sequence of GD1 (2,739 nucleotides [nt]) with VN (2,741 nt) indicated that they shared 86.2 % nt sequence identity. GD1 and VN shared the highest nucleotide sequence identity at 86.7 % and 91.4 % respectively, with isolate TY01 of pouzolzia golden mosaic virus (PGMV-TY01), another begomovirus isolated from P. zeylanica. Phylogenetic analysis revealed that GD1, VN, and PGMV-TY01 were members of a distinct begomovirus clade. Based on the ICTV guidelines for begomoviral species demarcation, GD1 belongs to a new begomovirus species, for which the name Pouzolzia yellow mosaic virus is proposed. Likewise, VN represents a previously unreported strain of PGMV. Recombination analysis predicted that VN was a recombinant between PGMV-TY01 and ageratum yellow vein China virus isolate G13 (AYVCNV-G13), and that PGMV-TY01 and VN were likely the parents of GD1 through recombination with allamanda leaf curl virus isolate G10 (AlLCV-G10), a begomovirus endemic to Guangdong Province of China.
• Tata-hangy, W., Sseruwagi, P., Shirima, R. R., Okao-okuja, G., Obiero, H., Ndyetabula, I., Masembe, C., Legg, J. P., Jeremiah, S. C., Herrmann, H. W., Gashaka, G., Brown, J. K., Boniface, S., & Bigirimana, S. (2014). Spatio-temporal patterns of genetic change amongst populations of cassava Bemisia tabaci whiteflies driving virus pandemics in East and Central Africa.. Virus research, 186, 61-75. doi:10.1016/j.virusres.2013.11.018
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  The greatest current threat to cassava in sub-Saharan Africa, is the continued expansion of plant virus pandemics being driven by super-abundant populations of the whitefly vector, Bemisia tabaci. To track the association of putatively genetically distinct populations of B. tabaci with pandemics of cassava mosaic disease (CMD) and cassava brown streak disease (CBSD), a comprehensive region-wide analysis examined the phylogenetic relationships and population genetics of 642 B. tabaci adults sampled from cassava in six countries of East and Central Africa, between 1997 and 2010, using a mitochondrial DNA cytochrome oxidase I marker (780 bases). Eight phylogenetically distinct groups were identified, including one, designated herein as 'East Africa 1' (EA1), not previously described. The three most frequently occurring groups comprised >95% of all samples. Among these, the Sub-Saharan Africa 2 (SSA2) group diverged by c. 8% from two SSA1 sub-groups (SSA1-SG1 and SSA1-SG2), which themselves were 1.9% divergent. During the 14-year study period, the group associated with the CMD pandemic expansion shifted from SSA2 to SSA1-SG1. Population genetics analyses of SSA1, using Tajima's D, Fu's Fs and Rojas' R2 statistics confirmed a temporal transition in SSA1 populations from neutrally evolving at the outset, to rapidly expanding from 2000 to 2003, then back to populations more at equilibrium after 2004. Based on available evidence, hybrid introgression appears to be the most parsimonious explanation for the switch from SSA2 to SSA1-SG1 in whitefly populations driving cassava virus pandemics in East and Central Africa.
• Varsani, A., Martin, D. P., Navas-Castillo, J., Moriones, E., Hernández-Zepeda, C., Idris, A., Murilo Zerbini, F., & Brown, J. K. (2014). Revisiting the classification of curtoviruses based on genome-wide pairwise identity. Archives of Virology, 159(Issue 7). doi:10.1007/s00705-014-1982-x
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  Members of the genus Curtovirus (family Geminiviridae) are important pathogens of many wild and cultivated plant species. Until recently, relatively few full curtovirus genomes have been characterised. However, with the 19 full genome sequences now available in public databases, we revisit the proposed curtovirus species and strain classification criteria. Using pairwise identities coupled with phylogenetic evidence, revised species and strain demarcation guidelines have been instituted. Specifically, we have established 77% genome-wide pairwise identity as a species demarcation threshold and 94% genome-wide pairwise identity as a strain demarcation threshold. Hence, whereas curtovirus sequences with >77% genome-wide pairwise identity would be classified as belonging to the same species, those sharing >94% identity would be classified as belonging to the same strain. We provide step-by-step guidelines to facilitate the classification of newly discovered curtovirus full genome sequences and a set of defined criteria for naming new species and strains. The revision yields three curtovirus species: Beet curly top virus (BCTV), Spinach severe surly top virus (SpSCTV) and Horseradish curly top virus (HrCTV). © 2014 Springer-Verlag Wien.
• Varsani, A., Martin, D. P., Navas-Castillo, J., Moriones, E., Hernández-Zepeda, C., Idris, A., Zerbini, F. M., & Brown, J. K. (2014). Revisiting the classification of curtoviruses based on genome-wide pairwise identity. Archives of Virology, 159, 1873-1882.
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  Varsani, A., Martin, D.P., Navas-Castillo, J., Moriones, E., Hernández-Zepeda, C., Idris, A.M., Murilo, F., Zerbini, F.M., and Brown, J.K. 2014. Revisiting the classification of curtoviruses based on genome-wide pairwise identity. Arch. Virol. 159: 1873-1882.
• Varsani, A., Navas-Castillo, J., Moriones, E., Hernández-Zepeda, C., Idris, A., Brown, J. K., Murilo Zerbini, F., & Martin, D. P. (2014). Establishment of three new genera in the family Geminiviridae: Becurtovirus, Eragrovirus and Turncurtovirus. Archives of Virology, 159(Issue 8). doi:10.1007/s00705-014-2050-2
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  The family Geminiviridae includes plant-infecting circular single-stranded DNA viruses that have geminate particle morphology. Members of this family infect both monocotyledonous and dicotyledonous plants and have a nearly global distribution. With the advent of new molecular tools and low-cost sequencing, there has been a significant increase in the discovery of new geminiviruses in various cultivated and non-cultivated plants. In this communication, we highlight the establishment of three new genera (Becurtovirus, Eragrovirus and Turncurtovirus) to accommodate various recently discovered geminiviruses that are highly divergent and, in some cases, have unique genome architectures. The genus Becurtovirus has two viral species, Beet curly top Iran virus (28 isolates; leafhopper vector Circulifer haematoceps) and Spinach curly top Arizona virus (1 isolate; unknown vector), whereas the genera Eragrovirus and Turncurtovirus each have a single assigned species: Eragrostis curvula streak virus (6 isolates; unknown vector) and Turnip curly top virus (20 isolates; leafhopper vector Circulifer haematoceps), respectively. Based on analysis of all of the genome sequences available in public databases for each of the three new genera, we provide guidelines and protocols for species and strain classification within these three new genera. © 2014 Springer-Verlag Wien.
• Varsani, A., Navas-Castillo, J., Moriones, E., Hernández-Zepeda, C., Idris, A., Brown, J. K., Zerbini, F. M., & Martin, D. P. (2014). Establishment of three new genera in the family Geminiviridae: Becurtovirus, Eragrovirus and Turncurtovirus. Archives of Virology, 159, 2193-2203.
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  Varsani, A., Navas-Castillo, J., Moriones, E., Hernández-Zepeda, C., Idris, A.M., Brown, J.K., Zerbini, F. M., Martin, D.P. 2014. Establishment of three new genera in the family Geminiviridae: Becurtovirus, Eragrovirus and Turncurtovirus. Arch. Virol. 159: 2193-2203.
• Zia-ur-rehman, M., Herrmann, H. W., Hameed, U., Haider, H., & Brown, J. K. (2014). Begomovirus diversity, phylogeography, and population genetics in cultivated and uncultivated plant ecosystems in Pakistan. Crop Protection, 61, 104. doi:10.1016/j.cropro.2013.12.045
• Brown, J. K. (2013). A genome-wide pairwise-identity-based proposalfor the classification of viruses in the genus, Mastrevirus (family, Geminiviridae).. Archives of Virology, 158:(1411-1424).
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  Muhire, B., D.P. Martin, J.K. Brown, J. Navas-Castillo, E. Moriones, F.M. Zerbini, R. Rivera-Bustamante,&#8232;V. G. Malathi, R. W. Briddon, and A. Varsani. 2013. A genome-wide pairwise-identity-based proposal for the classification of viruses in the genus, Mastrevirus (family, Geminiviridae). Arch Virol. 158:1411-1424.
• Brown, J. K. (2013). A new previously undescribed monopartite begomovirus infecting Permna serratifolia in Vietnam.. Archives of Virology.
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  She, X., Z. He, and J.K. Brown. 2013. A new previously undescribed monopartite begomovirus infecting Permna serratifolia in Vietnam. Arch Virol DOI 10. 1007/s00705-013-1729-0.
• Brown, J. K. (2013). First detection of Cotton leaf curl Burewala virus and cognate Cotton leaf curl Multan betasatellite and Gossypium darwinii symptomless alphasatellite in symptomatic Luffa cylindrica in Pakistan.. Plant Disease, 97, 1094.
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  Ur-Rehman, Z., H.-W. Herrmann, U. Hameed, M.S. Haider, and J.K. Brown. 2013. First detection of Cotton leaf curl Burewala virus and cognate Cotton leaf curl Multan betasatellite and Gossypium darwinii symptomless alphasatellite in symptomatic Luffa cylindrica in Pakistan. Plant Dis. 97:1094 //dx.doi.org/10.1094/PDIS-12-12-1159-PDN.Disease Note (short report)
• Brown, J. K. (2013). Spatio-temporal patterns of genetic change amongst cassava Bemisia tabaci whiteflies driving virus pandemics in East and Central Africa.. Virus Research, 158, doi.org/10.1016/j.virusres.2013.11.018..
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  Legg, J.P., P. Sseruwagi, S, Boniface, G. Okao-Okuja, R. Shirima, S. Bigirimana, Gervais Gashaka, H.-W. Herrmann, S. Jeremiah, H. Obiero, I. Ndyetabula, W. Tata-Hangy, C. Masembe, and J. K. Brown. 2013. Spatio-temporal patterns of genetic change amongst cassava Bemisia tabaci whiteflies driving virus pandemics in East and Central Africa. Virus Res. doi.org/10.1016/j.virusres.2013.11.018.
• Brown, J. K., & Brown, J. K. (2013). Phylogenetic relationships, recombination analysis, and genetic variability among diverse variants of Tomato yellow leaf curl virus in Iran and the Arabian Peninsula: further support for a TYLCV-center of diversity.. Archives of Virology, 158, DOI 10.1007/s00705-013-1851-z..
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  Hosseinzadeh, M.R., M. Shamsbakhsh, S. Kazempour Osalou, and J.K. Brown. 2013. Phylogenetic relationships, recombination analysis, and genetic variability among diverse variants of Tomato yellow leaf curl virus in Iran and the Arabian Peninsula: further support for a TYLCV-center of diversity. Arch. Virol. 158 DOI 10.1007/s00705-013-1851-z.
• Brown, J. K., & Fitzsimmons, K. (2014). Sonication based isolation and enrichment of Chlorella protothecoides chloroplasts for Illumina genome sequencing.. J. Appl. Phycology, 26, 209-218.
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  Angelova, A., S.H. Park, J. Kyndt, K. Fitzsimmons, and J.K. Brown. 2013. Sonication based isolation and enrichment of Chlorella protothecoides chloroplasts for Illumina genome sequencing. J. Appl. Phycology 26: 209-218. DOI: 10.1007/s10811-013-0125-1.
• Brown, J. K., Hernández-Zepeda, C., & Varsani, A. (2013). Intergeneric recombination between a new, spinach-infecting curtovirus and a new geminivirus belonging to the genus Becurtovirus: first New World exemplar. Archives of Virology, 11, 2245-2254.
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  A novel curtovirus, spinach severe curly top virus (SSCTV), was associated with symptomatic spinach plants collected from a commercial field in south-central Arizona during 2009. In addition, a second viral molecule of about 2.9 kb from the same spinach plants was amplified, cloned and sequenced. The latter isolate, herein named spinach curly top Arizona virus (SCTAV), was found to share 77&amp;amp;#160;% pairwise sequence identity with beet curly top Iran virus (BCTIV), a leafhopper-transmitted geminivirus that has been assigned to the new genus Becurtovirus. The SCTAV genome encodes three viral-sense genes, V1, V2, and V3, and two complementary-sense genes, C1 and C2. There was no evidence for the presence of either a C3 or C4 ORF in the genome sequence. The genome organization of SCTAV is not like that of New World curtoviruses but instead is similar to that of BCTIV, which, to date, is only known to be present in Iran. Consistent with this observation, SCTAV and BCTIV both contain the unusual nonanucleotide TAAGATT/CC and a replication-associated protein, Rep (or C1), that is more closely related to the mastrevirus Rep than to those of curtoviruses reported to date. Both SSCTV and SCTAV were found to have a recombinant genome containing sequences (AY548948) derived from ancestral SCTV sequences in the virion-sense portions of the genome. Agroinoculation of Nicotiana benthamiana (Domin) plants with the cloned genome of SCTAV resulted in infection of 95&amp;amp;#160;% of the plants and the development of severe curling symptoms, whereas only 20&amp;amp;#160;% of the SSCTV-inoculated plants were infected, developing only mild curling symptoms. When plants were co-inoculated with both viruses, the frequency of infection remained higher for SCTAV than for SSCTV (80&amp;amp;#160;% vs. 20&amp;amp;#160;%), indicating no evidence of synergistic effects between the two viruses with respect to efficiency of infection.
• Esterhuizen, L. L., Mabasa, K. G., Heerden, S. V., Czosnek, H., Brown, J. K., Heerden, H. V., & Rey, M. E. (2013). Genetic identification of members of the Bemisia tabaci cryptic species complex from South Africa reveals native and introduced haplotypes. Journal of Applied Entomology, 137(1-2), 122-135.
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  Abstract: The whitefly Bemisia tabaci cryptic species complex contains some important agricultural pest and virus vectors. Members of the complex have become serious pests in South Africa (SA) because of their feeding habit and their ability to transmit begomovirus species. Despite their economic importance, studies on the biology and distribution of B. tabaci in SA are limited. To this end, a survey was made to investigate the diversity and distribution of B. tabaci cryptic species in eight geographical locations (provinces) in SA, between 2002 and 2009, using the mitochondrial cytochrome oxidase I (mtCOI) sequences. Phylogenetic analysis revealed the presence of members from two endemic sub-Saharan Africa (SSAF) subclades coexisting with two introduced putative species. The SSAF-1 subclade includes cassava host-adapted B. tabaci populations, whereas the whiteflies collected from cassava and non-cassava hosts formed a distinct subclade, referred to as SSAF-5, and represent a new subclade among previously recognized southern Africa clades. Two introduced cryptic species, belonging to the Mediterranean and Middle East-Asia minor 1 clades, were identified and include the B and Q types. The B type showed the widest distribution, being present in five of the eight provinces explored in SA, infesting several host plants and predominating over the indigenous haplotypes. This is the first report of the occurrence of the exotic Q type in SA alongside the more widely distributed B type. Furthermore, mtCOI PCR-RFLP was developed for the SA context to allow rapid discrimination between the B, Q and SSAF putative species. The capacity to manage pests and disease effectively relies on knowledge of the identity of the agents causing the damage. Therefore, this study contributes to the understanding of South African B. tabaci species diversity, information needed for the development of knowledge-based disease management practices. © 2012 Blackwell Verlag, GmbH.
• Esterhuizen, L. L., Mabasa, K. G., Van Heerden, S. W., Czosnek, H., Brown, J. K., Van Heerden, H., & Rey, M. E. (2013). Genetic identification of members of the Bemisia tabaci cryptic species complex from South Africa reveals native and introduced haplotypes. Journal of Applied Entomology, 137(Issue 1-2). doi:10.1111/j.1439-0418.2012.01720.x
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  The whitefly Bemisia tabaci cryptic species complex contains some important agricultural pest and virus vectors. Members of the complex have become serious pests in South Africa (SA) because of their feeding habit and their ability to transmit begomovirus species. Despite their economic importance, studies on the biology and distribution of B. tabaci in SA are limited. To this end, a survey was made to investigate the diversity and distribution of B. tabaci cryptic species in eight geographical locations (provinces) in SA, between 2002 and 2009, using the mitochondrial cytochrome oxidase I (mtCOI) sequences. Phylogenetic analysis revealed the presence of members from two endemic sub-Saharan Africa (SSAF) subclades coexisting with two introduced putative species. The SSAF-1 subclade includes cassava host-adapted B. tabaci populations, whereas the whiteflies collected from cassava and non-cassava hosts formed a distinct subclade, referred to as SSAF-5, and represent a new subclade among previously recognized southern Africa clades. Two introduced cryptic species, belonging to the Mediterranean and Middle East-Asia minor 1 clades, were identified and include the B and Q types. The B type showed the widest distribution, being present in five of the eight provinces explored in SA, infesting several host plants and predominating over the indigenous haplotypes. This is the first report of the occurrence of the exotic Q type in SA alongside the more widely distributed B type. Furthermore, mtCOI PCR-RFLP was developed for the SA context to allow rapid discrimination between the B, Q and SSAF putative species. The capacity to manage pests and disease effectively relies on knowledge of the identity of the agents causing the damage. Therefore, this study contributes to the understanding of South African B. tabaci species diversity, information needed for the development of knowledge-based disease management practices. © 2012 Blackwell Verlag, GmbH.
• Hernández-Zepeda, C., Varsani, A., & Brown, J. K. (2013). Intergeneric recombination between a new, spinach-infecting curtovirus and a new geminivirus belonging to the genus Becurtovirus: First New World exemplar. Archives of Virology, 158(11), 2245-2254.
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  PMID: 23708296;Abstract: A novel curtovirus, spinach severe curly top virus (SSCTV), was associated with symptomatic spinach plants collected from a commercial field in south-central Arizona during 2009. In addition, a second viral molecule of about 2.9 kb from the same spinach plants was amplified, cloned and sequenced. The latter isolate, herein named spinach curly top Arizona virus (SCTAV), was found to share 77 % pairwise sequence identity with beet curly top Iran virus (BCTIV), a leafhopper-transmitted geminivirus that has been assigned to the new genus Becurtovirus. The SCTAV genome encodes three viral-sense genes, V1, V2, and V3, and two complementary-sense genes, C1 and C2. There was no evidence for the presence of either a C3 or C4 ORF in the genome sequence. The genome organization of SCTAV is not like that of New World curtoviruses but instead is similar to that of BCTIV, which, to date, is only known to be present in Iran. Consistent with this observation, SCTAV and BCTIV both contain the unusual nonanucleotide TAAGATT/CC and a replication-associated protein, Rep (or C1), that is more closely related to the mastrevirus Rep than to those of curtoviruses reported to date. Both SSCTV and SCTAV were found to have a recombinant genome containing sequences (AY548948) derived from ancestral SCTV sequences in the virion-sense portions of the genome. Agroinoculation of Nicotiana benthamiana (Domin) plants with the cloned genome of SCTAV resulted in infection of 95 % of the plants and the development of severe curling symptoms, whereas only 20 % of the SSCTV-inoculated plants were infected, developing only mild curling symptoms. When plants were co-inoculated with both viruses, the frequency of infection remained higher for SCTAV than for SSCTV (80 % vs. 20 %), indicating no evidence of synergistic effects between the two viruses with respect to efficiency of infection. © 2013 Springer-Verlag Wien.
• Hernández-Zepeda, C., Varsani, A., & Brown, J. K. (2013). Intergeneric recombination between a new, spinach-infecting curtovirus and a new geminivirus belonging to the genus Becurtovirus: First New World exemplar. Archives of Virology, 158(Issue 11). doi:10.1007/s00705-013-1733-4
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  A novel curtovirus, spinach severe curly top virus (SSCTV), was associated with symptomatic spinach plants collected from a commercial field in south-central Arizona during 2009. In addition, a second viral molecule of about 2.9 kb from the same spinach plants was amplified, cloned and sequenced. The latter isolate, herein named spinach curly top Arizona virus (SCTAV), was found to share 77 % pairwise sequence identity with beet curly top Iran virus (BCTIV), a leafhopper-transmitted geminivirus that has been assigned to the new genus Becurtovirus. The SCTAV genome encodes three viral-sense genes, V1, V2, and V3, and two complementary-sense genes, C1 and C2. There was no evidence for the presence of either a C3 or C4 ORF in the genome sequence. The genome organization of SCTAV is not like that of New World curtoviruses but instead is similar to that of BCTIV, which, to date, is only known to be present in Iran. Consistent with this observation, SCTAV and BCTIV both contain the unusual nonanucleotide TAAGATT/CC and a replication-associated protein, Rep (or C1), that is more closely related to the mastrevirus Rep than to those of curtoviruses reported to date. Both SSCTV and SCTAV were found to have a recombinant genome containing sequences (AY548948) derived from ancestral SCTV sequences in the virion-sense portions of the genome. Agroinoculation of Nicotiana benthamiana (Domin) plants with the cloned genome of SCTAV resulted in infection of 95 % of the plants and the development of severe curling symptoms, whereas only 20 % of the SSCTV-inoculated plants were infected, developing only mild curling symptoms. When plants were co-inoculated with both viruses, the frequency of infection remained higher for SCTAV than for SSCTV (80 % vs. 20 %), indicating no evidence of synergistic effects between the two viruses with respect to efficiency of infection. © 2013 Springer-Verlag Wien.
• Legg, J. P., Sseruwagi, P., Boniface, S., Okao-Okuja, G., Shirima, R., Bigirimana, S., Gashaka, G., Herrmann, H., Jeremiah, S., Obiero, H., Ndyetabula, I., Tata-Hangy, W., Masembe, C., & Brown, J. K. (2013). Spatio-temporal patterns of genetic change amongst populations of cassava Bemisia tabaci whiteflies driving virus pandemics in East and Central Africa. Virus Research.
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  Abstract: The greatest current threat to cassava in sub-Saharan Africa, is the continued expansion of plant virus pandemics being driven by super-abundant populations of the whitefly vector, Bemisia tabaci. To track the association of putatively genetically distinct populations of B. tabaci with pandemics of cassava mosaic disease (CMD) and cassava brown streak disease (CBSD), a comprehensive region-wide analysis examined the phylogenetic relationships and population genetics of 642 B. tabaci adults sampled from cassava in six countries of East and Central Africa, between 1997 and 2010, using a mitochondrial DNA cytochrome oxidase I marker (780 bases). Eight phylogenetically distinct groups were identified, including one, designated herein as 'East Africa 1' (EA1), not previously described. The three most frequently occurring groups comprised >95% of all samples. Among these, the Sub-Saharan Africa 2 (SSA2) group diverged by c. 8% from two SSA1 sub-groups (SSA1-SG1 and SSA1-SG2), which themselves were 1.9% divergent. During the 14-year study period, the group associated with the CMD pandemic expansion shifted from SSA2 to SSA1-SG1. Population genetics analyses of SSA1, using Tajima's D, Fu's F s and Rojas' R 2 statistics confirmed a temporal transition in SSA1 populations from neutrally evolving at the outset, to rapidly expanding from 2000 to 2003, then back to populations more at equilibrium after 2004. Based on available evidence, hybrid introgression appears to be the most parsimonious explanation for the switch from SSA2 to SSA1-SG1 in whitefly populations driving cassava virus pandemics in East and Central Africa. © 2013 Elsevier B.V. All rights reserved.
• Leke, W. N., Sattar, M. N., Ngane, E. B., Ngeve, J. M., Kvarnheden, A., & Brown, J. K. (2013). Molecular characterization of begomoviruses and DNA satellites associated with okra leaf curl disease in Cameroon. Virus Research, 174(1-2), 116-125.
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  PMID: 23535770;Abstract: Okra leaf curl disease (OLCD) is the most important viral disease of okra in West Africa. In this study, a complex of begomoviruses and associated DNA satellites were identified in symptomatic okra plants from southwestern Cameroon. Sequence analyses showed that two of the plants (Lik1 and Njo5) were infected with a begomovirus being a recombinant of cotton leaf curl Gezira virus (CLCuGeV) and okra yellow crinkle virus (OYCrV). The recombinant genome shared highest nucleotide identity with isolates of CLCuGeV at 87.8% and is therefore considered to be member of a new begomovirus species, Okra leaf curl Cameroon virus (OLCuCMV). One plant (Mue5) was infected by a begomovirus with 95.8% nucleotide identy to CLCuGeV, while in the plants Lik1, Mue1 and Njo5, a begomovirus was identified showing highest nucleotide identity at 93.7% with OYCrV. The nucleotide comparisons and phylogenetic analyses suggest that these isolates represent new Cameroonian strains of CLCuGeV and OYCrV (CLCuGeV-CM and OYCrV-CM). Mixed infection of OLCuCMV and OYCrV-CM was found in two of the plants. A betasatellite and two divergent alphasatellites were also associated with the begomoviruses. The betasatellite was identified as cotton leaf curl Gezira betasatellite (CLCuGeB) with the highest nucleotide identity at 93.3% to other African isolates of CLCuGeB. The alphasatellites, herein named Alpha-1 and Alpha-2, shared 97.3% and 95.2% identity, respectively, with cotton leaf curl Gezira alphasatellite (CLCuGeA) and okra leaf curl Burkina Faso alphasatellite (OLCuBFA). These collective results emphasize the extent of diversity among okra-infecting begomovirus-satellite complexes in western Africa. © 2013 Elsevier B.V.
• Leke, W. N., Sattar, M. N., Ngane, E. B., Ngeve, J. M., Kvarnheden, A., & Brown, J. K. (2013). Molecular characterization of begomoviruses and DNA satellites associated with okra leaf curl disease in Cameroon. Virus Research, 174(Issue 1-2). doi:10.1016/j.virusres.2013.03.010
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  Okra leaf curl disease (OLCD) is the most important viral disease of okra in West Africa. In this study, a complex of begomoviruses and associated DNA satellites were identified in symptomatic okra plants from southwestern Cameroon. Sequence analyses showed that two of the plants (Lik1 and Njo5) were infected with a begomovirus being a recombinant of cotton leaf curl Gezira virus (CLCuGeV) and okra yellow crinkle virus (OYCrV). The recombinant genome shared highest nucleotide identity with isolates of CLCuGeV at 87.8% and is therefore considered to be member of a new begomovirus species, Okra leaf curl Cameroon virus (OLCuCMV). One plant (Mue5) was infected by a begomovirus with 95.8% nucleotide identy to CLCuGeV, while in the plants Lik1, Mue1 and Njo5, a begomovirus was identified showing highest nucleotide identity at 93.7% with OYCrV. The nucleotide comparisons and phylogenetic analyses suggest that these isolates represent new Cameroonian strains of CLCuGeV and OYCrV (CLCuGeV-CM and OYCrV-CM). Mixed infection of OLCuCMV and OYCrV-CM was found in two of the plants. A betasatellite and two divergent alphasatellites were also associated with the begomoviruses. The betasatellite was identified as cotton leaf curl Gezira betasatellite (CLCuGeB) with the highest nucleotide identity at 93.3% to other African isolates of CLCuGeB. The alphasatellites, herein named Alpha-1 and Alpha-2, shared 97.3% and 95.2% identity, respectively, with cotton leaf curl Gezira alphasatellite (CLCuGeA) and okra leaf curl Burkina Faso alphasatellite (OLCuBFA). These collective results emphasize the extent of diversity among okra-infecting begomovirus-satellite complexes in western Africa. © 2013 Elsevier B.V.
• Leke, W., Sattar, M., Ngane, E., Negeve, J., Kvarnheden, A., & Brown, J. (2013). Diverse group of helper begomoviruses and satellite DNAs infecting okra in Cameroon. Virus Res.
• Muhire, B., Martin, D. P., Brown, J. K., Navas-Castillo, J., Moriones, E., Zerbini, F. M., Rivera-Bustamante, R., Malathi, V. G., Briddon, R. W., & Varsani, A. (2013). A genome-wide pairwise-identity-based proposal for the classification of viruses in the genus Mastrevirus (family Geminiviridae). Archives of Virology, 158(Issue 6). doi:10.1007/s00705-012-1601-7
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  Recent advances in the ease with which the genomes of small circular single-stranded DNA viruses can be amplified, cloned, and sequenced have greatly accelerated the rate at which full genome sequences of mastreviruses (family Geminiviridae, genus Mastrevirus) are being deposited in public sequence databases. Although guidelines currently exist for species-level classification of newly determined, complete mastrevirus genome sequences, these are difficult to apply to large sequence datasets and are permissive enough that, effectively, a high degree of leeway exists for the proposal of new species and strains. The lack of a standardised and rigorous method for testing whether a new genome sequence deserves such a classification is resulting in increasing numbers of questionable mastrevirus species proposals. Importantly, the recommended sequence alignment and pairwise identity calculation protocols of the current guidelines could easily be modified to make the classification of newly determined mastrevirus genome sequences significantly more objective. Here, we propose modified versions of these protocols that should substantially minimise the degree of classification inconsistency that is permissible under the current system. To facilitate the objective application of these guidelines for mastrevirus species demarcation, we additionally present a user-friendly computer program, SDT (species demarcation tool), for calculating and graphically displaying pairwise genome identity scores. We apply SDT to the 939 full genome sequences of mastreviruses that were publically available in May 2012, and based on the distribution of pairwise identity scores yielded by our protocol, we propose mastrevirus species and strain demarcation thresholds of >78 % and >94 % identity, respectively. © 2013 Springer-Verlag Wien.
• Muhire, B., Martin, D. P., Brown, J. K., Navas-Castillo, J., Moriones, E., Zerbini, F., Rivera-Bustamante, R., Malathi, V. G., Briddon, R. W., & Varsani, A. (2013). A genome-wide pairwise-identity-based proposal for the classification of viruses in the genus Mastrevirus (family Geminiviridae). Archives of Virology, 158(6), 1411-1424.
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  PMID: 23340592;Abstract: Recent advances in the ease with which the genomes of small circular single-stranded DNA viruses can be amplified, cloned, and sequenced have greatly accelerated the rate at which full genome sequences of mastreviruses (family Geminiviridae, genus Mastrevirus) are being deposited in public sequence databases. Although guidelines currently exist for species-level classification of newly determined, complete mastrevirus genome sequences, these are difficult to apply to large sequence datasets and are permissive enough that, effectively, a high degree of leeway exists for the proposal of new species and strains. The lack of a standardised and rigorous method for testing whether a new genome sequence deserves such a classification is resulting in increasing numbers of questionable mastrevirus species proposals. Importantly, the recommended sequence alignment and pairwise identity calculation protocols of the current guidelines could easily be modified to make the classification of newly determined mastrevirus genome sequences significantly more objective. Here, we propose modified versions of these protocols that should substantially minimise the degree of classification inconsistency that is permissible under the current system. To facilitate the objective application of these guidelines for mastrevirus species demarcation, we additionally present a user-friendly computer program, SDT (species demarcation tool), for calculating and graphically displaying pairwise genome identity scores. We apply SDT to the 939 full genome sequences of mastreviruses that were publically available in May 2012, and based on the distribution of pairwise identity scores yielded by our protocol, we propose mastrevirus species and strain demarcation thresholds of >78 % and >94 % identity, respectively. © 2013 Springer-Verlag Wien.
• She, X., He, Z., & Brown, J. K. (2013). A new, previously undescribed monopartite begomovirus infecting Premna serratifolia in Vietnam. Archives of Virology, 158(Issue 11). doi:10.1007/s00705-013-1729-0
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  The complete genome sequence of a monopartite begomovirus isolate infecting Creek Premna (Premna serratifolia L.) plants that exhibited leaf curl, vein swelling, and enation symptoms in Nha Trang, Vietnam, was cloned and sequenced. It comprises 2,753 nucleotides (JQ793786) and has a typical organization of begomoviruses DNA-A with AV1 and AV2 open reading frames (ORFs) in the viral-sense strand and AC1, AC2, AC3, AC4 and AC5 ORFs in the complementary-sense strand. The full-length genome sequence of the isolate (clone VN7) shared the highest level of nucleotide sequence identity (83 %) with the isolate IN:Pusa:Tb:10 of tobacco leaf curl Pusa virus (HQ180391). The phylogenetic relationship of VN7 to other begomoviruses was also investigated. VN7 grouped most closely with a clade containing begomoviruses from China, India and Japan. According to the current taxonomic criteria for the genus Begomovirus, family Geminiviridae, the isolate VN7 represents a new species, herein named "Premna leaf curl virus" (PrLCV). © 2013 Springer-Verlag Wien.
• She, X., Zifu, H. e., & Brown, J. K. (2013). A new, previously undescribed monopartite begomovirus infecting Premna serratifolia in Vietnam. Archives of Virology, 158(11), 2425-2428.
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  PMID: 23749046;Abstract: The complete genome sequence of a monopartite begomovirus isolate infecting Creek Premna (Premna serratifolia L.) plants that exhibited leaf curl, vein swelling, and enation symptoms in Nha Trang, Vietnam, was cloned and sequenced. It comprises 2,753 nucleotides (JQ793786) and has a typical organization of begomoviruses DNA-A with AV1 and AV2 open reading frames (ORFs) in the viral-sense strand and AC1, AC2, AC3, AC4 and AC5 ORFs in the complementary-sense strand. The full-length genome sequence of the isolate (clone VN7) shared the highest level of nucleotide sequence identity (83 %) with the isolate IN:Pusa:Tb:10 of tobacco leaf curl Pusa virus (HQ180391). The phylogenetic relationship of VN7 to other begomoviruses was also investigated. VN7 grouped most closely with a clade containing begomoviruses from China, India and Japan. According to the current taxonomic criteria for the genus Begomovirus, family Geminiviridae, the isolate VN7 represents a new species, herein named "Premna leaf curl virus" (PrLCV). © 2013 Springer-Verlag Wien.
• Zia-Ur-Rehman, M., Herrmann, H. -., Hameed, U., Haider, M. S., & Brown, J. K. (2013). First detection of cotton leaf curl Burewala virus and cognate cotton leaf curl Multan betasatellite and Gossypium darwinii symptomless alphasatellite in symptomatic luffa cylindrica in Pakistan. Plant Disease, 97(8), 1122-.
• Zia-Ur-Rehman, M., Herrmann, H. W., Hameed, U., Haider, M. S., & Brown, J. K. (2013). First detection of cotton leaf curl Burewala virus and cognate cotton leaf curl Multan betasatellite and Gossypium darwinii symptomless alphasatellite in symptomatic luffa cylindrica in Pakistan. Plant Disease, 97(Issue 8). doi:10.1094/pdis-12-12-1159-pdn
• Chu, D., Tao, Y. L., Zhang, Y. J., Wan, F. H., & Brown, J. K. (2012). Effects of host, temperature and relative humidity on competitive displacement of two invasive Bemisia tabaci biotypes [Q and B]. Insect Science, 19(Issue 5). doi:10.1111/j.1744-7917.2011.01500.x
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  Bemisia tabaci shifted unexpectedly in China from a predominance of B biotype to Q biotype during 2005-2008. This observation stimulated an interest in investigating whether environmental factors, including host, temperature and relative humidity (RH) could possibly explain the observed shift in biotypes distribution. Results indicated that all three parameters examined influenced biotype survivability. The percentage of B biotype, when reared together on pepper plants with the Q biotype, decreased significantly from 66.7% in the founder population, to 13.6% and 3.7% in the first and second generations, respectively. When the B (founder at 66.7%) and Q (founder at 33.3%) biotypes were reared together on eggplant alone, or on pepper-plus-eggplant combination, the population size of the B biotype either remained constant, or increased somewhat in the first and second generations. On eggplant, the effects of RH and temperature on the competitiveness between the Q and B biotypes (3 pairs of Q and 6 pairs of B) were not significant. © 2012 Institute of Zoology, Chinese Academy of Sciences.
• Chu, D., Tao, Y., Zhang, Y., Wan, F., & Brown, J. (2012). Effects of host, temperature, and humidity on competitive displacement of two invasive Bemisia tabaci biotypes [Q and B]. Insect Sci, 19, 595-603.
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  DOI 10.1111/j.1744-7917.2011.01500.x
• Chu, D., Tao, Y., Zhang, Y., Wan, F., & Brown, J. K. (2012). Effects of host, temperature and relative humidity on competitive displacement of two invasive Bemisia tabaci biotypes [Q and B]. Insect Science, 19(5), 595-603.
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  Abstract: Bemisia tabaci shifted unexpectedly in China from a predominance of B biotype to Q biotype during 2005-2008. This observation stimulated an interest in investigating whether environmental factors, including host, temperature and relative humidity (RH) could possibly explain the observed shift in biotypes distribution. Results indicated that all three parameters examined influenced biotype survivability. The percentage of B biotype, when reared together on pepper plants with the Q biotype, decreased significantly from 66.7% in the founder population, to 13.6% and 3.7% in the first and second generations, respectively. When the B (founder at 66.7%) and Q (founder at 33.3%) biotypes were reared together on eggplant alone, or on pepper-plus-eggplant combination, the population size of the B biotype either remained constant, or increased somewhat in the first and second generations. On eggplant, the effects of RH and temperature on the competitiveness between the Q and B biotypes (3 pairs of Q and 6 pairs of B) were not significant. © 2012 Institute of Zoology, Chinese Academy of Sciences.
• Cicero, J. M., & Brown, J. K. (2012). Ultrastructural studies of the salivary duct system in the whitefly vector bemisia tabaci (Aleyrodidae: Hemiptera). Annals of the Entomological Society of America, 105(5), 701-717.
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  Abstract: Bemisia tabaci (Gennadius) transmits plant viruses of the genus Begomovirus in a circulative manner, and once acquired, virus particles persist and are transmissible for the life of the vector. Saliva is generated by primary and accessory salivary gland cells of the paired, bilaterally symmetrical salivary gland system. It travels from secretory cells, through the internal ductules, to the external ducts, which in turn carry it to the oral region where the so-called salivary pump and the stylets occur. The ducts of either side consist of at least four componentstwo gland ducts, one lateral duct, and one postmedial duct. Gland ducts start, respectively, at the hilum of each gland, and extend independently of each other before fusing together by their basal laminae to become the biluminal lateral duct. The biluminal lateral duct merges into the uniluminal postmedial duct. The lateral and postmedial ducts make intimate contact with muscles in its area, including one involved in governing the retractable labial shaft. The labium consists of external and internal halves. During retraction/protraction, the latter half moves through the second intercommissural space. The postmedial ducts track anteriorly around either side of it, and fuse together at the body's midline to form the biluminal medial duct. This duct drains into the salivary pump. The retortiform organs are involved in stylet regeneration. Maxillary stylets have grooves and ridges that interlock to form the salivary and food canals. In developmental terms, the salivary canal results from failure of one ridge to fill its corresponding groove. © 2012 Entomological Society of America.
• Cicero, J. M., & Brown, J. K. (2012). Ultrastructural studies of the salivary duct system in the whitefly vector bemisia tabaci (Aleyrodidae: Hemiptera). Annals of the Entomological Society of America, 105(Issue 5). doi:10.1603/an12030
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  Bemisia tabaci (Gennadius) transmits plant viruses of the genus Begomovirus in a circulative manner, and once acquired, virus particles persist and are transmissible for the life of the vector. Saliva is generated by primary and accessory salivary gland cells of the paired, bilaterally symmetrical salivary gland system. It travels from secretory cells, through the internal ductules, to the external ducts, which in turn carry it to the oral region where the so-called salivary pump and the stylets occur. The ducts of either side consist of at least four componentstwo gland ducts, one lateral duct, and one postmedial duct. Gland ducts start, respectively, at the hilum of each gland, and extend independently of each other before fusing together by their basal laminae to become the biluminal lateral duct. The biluminal lateral duct merges into the uniluminal postmedial duct. The lateral and postmedial ducts make intimate contact with muscles in its area, including one involved in governing the retractable labial shaft. The labium consists of external and internal halves. During retraction/protraction, the latter half moves through the second intercommissural space. The postmedial ducts track anteriorly around either side of it, and fuse together at the body's midline to form the biluminal medial duct. This duct drains into the salivary pump. The retortiform organs are involved in stylet regeneration. Maxillary stylets have grooves and ridges that interlock to form the salivary and food canals. In developmental terms, the salivary canal results from failure of one ridge to fill its corresponding groove. © 2012 Entomological Society of America.
• Cicero, J., & Brown, J. (2012). Ultrastructural studies of the salivary duct system in the whitefly vector Bemisia tabaci (Aleyrodidae: Hemiptera). Ann. Entomol. Soc. Am, 105, 701-717.
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  DOI: http://dx.doi.org/10.1603/AN12030).
• Esterhuizen, L., Mabasa, K., van, H. S., Czosnek, H., Brown, J., van, H. J., & Rey, M. (2012). Genetic identification of members of the Bemisia tabaci cryptic species complex from South Africa reveals native and introduced haplotypes. J. Appl. Entomol.
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  DOI: 10.1111/j.1439-0418.2012.01720.x
• Götz, M., Popovski, S., Kollenberg, M., Gorovits, R., Brown, J. K., Cicero, J. M., Czosnek, H., Winter, S., & Ghanim, M. (2012). Implication of Bemisia tabaci heat shock protein 70 in begomovirus-whitefly interactions. Journal of Virology, 86(24), 13241-13252.
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  PMID: 23015709;PMCID: PMC3503126;Abstract: The whitefly Bemisia tabaci (Gennadius) is a major cosmopolitan pest capable of feeding on hundreds of plant species and transmits several major plant viruses. The most important and widespread viruses vectored by B. tabaci are in the genus Begomovirus, an unusual group of plant viruses owing to their small, single-stranded DNA genome and geminate particle morphology. B. tabaci transmits begomoviruses in a persistent circulative nonpropagative manner. Evidence suggests that the whitefly vector encounters deleterious effects following Tomato yellow leaf curl virus (TYLCV) ingestion and retention. However, little is known about the molecular and cellular basis underlying these coevolved begomovirus-whitefly interactions. To elucidate these interactions, we undertook a study using B. tabaci microarrays to specifically describe the responses of the transcriptomes of whole insects and dissected midguts following TYLCV acquisition and retention. Microarray, real-time PCR, and Western blot analyses indicated that B. tabaci heat shock protein 70 (HSP70) specifically responded to the presence of the monopartite TYLCV and the bipartite Squash leaf curl virus. Immunocapture PCR, protein coimmunoprecipitation, and virus overlay protein binding assays showed in vitro interaction between TYLCV and HSP70. Fluorescence in situ hybridization and immunolocalization showed colocalization of TYLCV and the bipartite Watermelon chlorotic stunt virus virions and HSP70 within midgut epithelial cells. Finally, membrane feeding of whiteflies with anti-HSP70 antibodies and TYLCV virions showed an increase in TYLCV transmission, suggesting an inhibitory role for HSP70 in virus transmission, a role that might be related to protection against begomoviruses while translocating in the whitefly. © 2012, American Society for Microbiology.
• Götz, M., Popovski, S., Kollenberg, M., Gorovits, R., Brown, J. K., Cicero, J. M., Czosnek, H., Winter, S., & Ghanim, M. (2012). Implication of Bemisia tabaci heat shock protein 70 in begomovirus-whitefly interactions. Journal of Virology, 86(Issue 24). doi:10.1128/jvi.00880-12
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  The whitefly Bemisia tabaci (Gennadius) is a major cosmopolitan pest capable of feeding on hundreds of plant species and transmits several major plant viruses. The most important and widespread viruses vectored by B. tabaci are in the genus Begomovirus, an unusual group of plant viruses owing to their small, single-stranded DNA genome and geminate particle morphology. B. tabaci transmits begomoviruses in a persistent circulative nonpropagative manner. Evidence suggests that the whitefly vector encounters deleterious effects following Tomato yellow leaf curl virus (TYLCV) ingestion and retention. However, little is known about the molecular and cellular basis underlying these coevolved begomovirus-whitefly interactions. To elucidate these interactions, we undertook a study using B. tabaci microarrays to specifically describe the responses of the transcriptomes of whole insects and dissected midguts following TYLCV acquisition and retention. Microarray, real-time PCR, and Western blot analyses indicated that B. tabaci heat shock protein 70 (HSP70) specifically responded to the presence of the monopartite TYLCV and the bipartite Squash leaf curl virus. Immunocapture PCR, protein coimmunoprecipitation, and virus overlay protein binding assays showed in vitro interaction between TYLCV and HSP70. Fluorescence in situ hybridization and immunolocalization showed colocalization of TYLCV and the bipartite Watermelon chlorotic stunt virus virions and HSP70 within midgut epithelial cells. Finally, membrane feeding of whiteflies with anti-HSP70 antibodies and TYLCV virions showed an increase in TYLCV transmission, suggesting an inhibitory role for HSP70 in virus transmission, a role that might be related to protection against begomoviruses while translocating in the whitefly. © 2012, American Society for Microbiology.
• Idris, A. M., Abdullah, N. M., & Brown, J. K. (2012). Leaf curl diseases of two solanaceous species in Southwest Arabia are caused by a monopartite begomovirus evolutionarily most closely related to a species from the Nile Basin and unique suite of betasatellites. Virus Research, 169(1), 296-300.
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  PMID: 22841489;Abstract: The complete genome of 2780 bases was amplified using rolling circle amplification, and cloned, and sequenced for two distinct strains of the monopartite begomovirus Tomato leaf curl Sudan virus (ToLCSDV). The two strains shared 86-91% identity with the previously described ToLCSDV from the Nile Basin, and 90-91% identity with one another. One strain was cloned from symptomatic tomato plants from Tihamah (ToLCSDV-YE[YE:Tih:05]) while the other was cloned from symptomatic tobacco plants collected from Wadi Hadramaut (ToLCSDV-YE[YE:Had:89]). A distinct full-length betasatellite molecule (1352 bases) was cloned from the respective field-infected tomato and tobacco plants. Agro-inoculation of tomato and Nicotiana benthamiana plants with cloned partial tandem repeats of ToLCSDV-YE[YE:Tih11:05]) and the associated betasatellite, Tomato leaf curl Yemen betasatellite (ToLCYEB-[Tih:tom:137:05]), resulted in the reproduction of leaf curl disease symptoms in test plants like those observed in the field-infected plants. The betasatellite contributed to symptom severity in N. benthamiana test plants when it was co-inoculated with ToLCSDV-YE, compared to the milder symptoms that were observed in tobacco plants infected with the helper virus alone. © 2012 Elsevier B.V.
• Idris, A. M., Abdullah, N. M., & Brown, J. K. (2012). Leaf curl diseases of two solanaceous species in Southwest Arabia are caused by a monopartite begomovirus evolutionarily most closely related to a species from the Nile Basin and unique suite of betasatellites. Virus Research, 169(Issue 1). doi:10.1016/j.virusres.2012.07.014
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  The complete genome of 2780 bases was amplified using rolling circle amplification, and cloned, and sequenced for two distinct strains of the monopartite begomovirus Tomato leaf curl Sudan virus (ToLCSDV). The two strains shared 86-91% identity with the previously described ToLCSDV from the Nile Basin, and 90-91% identity with one another. One strain was cloned from symptomatic tomato plants from Tihamah (ToLCSDV-YE[YE:Tih:05]) while the other was cloned from symptomatic tobacco plants collected from Wadi Hadramaut (ToLCSDV-YE[YE:Had:89]). A distinct full-length betasatellite molecule (1352 bases) was cloned from the respective field-infected tomato and tobacco plants. Agro-inoculation of tomato and Nicotiana benthamiana plants with cloned partial tandem repeats of ToLCSDV-YE[YE:Tih11:05]) and the associated betasatellite, Tomato leaf curl Yemen betasatellite (ToLCYEB-[Tih:tom:137:05]), resulted in the reproduction of leaf curl disease symptoms in test plants like those observed in the field-infected plants. The betasatellite contributed to symptom severity in N. benthamiana test plants when it was co-inoculated with ToLCSDV-YE, compared to the milder symptoms that were observed in tobacco plants infected with the helper virus alone. © 2012 Elsevier B.V.
• Idris, A., Abdullah, N., & Brown, J. (2012). Leaf curl disease of two solanaceous species in Southwest Arabia are caused by a monopartite begomovirus evolutionarily most related to a species from the Nile Basin and a unique betasatellite. Virus Res, 169, 269-300.
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  Idris, A.M., Abdullah, N.M., and Brown, J.K. 2012. Leaf curl disease of two solanaceous species in Southwest Arabia are caused by a monopartite begomovirus evolutionarily most related to a species from the Nile Basin and a unique betasatellite. Virus Res. 169: 296-300.
• Leke, W. N., Brown, J. K., Ligthart, M. E., Sattar, N., Njualem, D. K., & Kvarnheden, A. (2012). Ageratum conyzoides: A host to a unique begomovirus disease complex in Cameroon. Virus Research, 163(1), 229-237.
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  PMID: 22001569;Abstract: Ageratum conyzoides (goat weed) is a widespread uncultivated species in Cameroon that exhibits leaf curl disease (LCD) symptoms suggestive of begomovirus infection. In Asia, different begomovirus-satellite complexes have been identified in A. conyzoides. The objective of this study was to determine the identity of the suspect begomoviruses and their associated satellites in A. conyzoides in Cameroon. The results indicated that all three symptomatic A. conyzoides plants examined were infected with a new begomovirus species, herein named Ageratum leaf curl Cameroon virus (ALCCMV). The ALCCMV genome sequences shared their highest identity, at 84.3-88.5%, with a group of tomato-infecting begomoviruses from West Africa. In addition, a betasatellite and an alphasatellite were cloned from the same symptomatic A. conyzoides plants. The betasatellite sequences shared limited sequence identity at 37% or less with the betasatellite Cotton leaf curl Gezira betasatellite, and the new betasatellite species is herein named Ageratum leaf curl Cameroon betasatellite (ALCCMB). The alphasatellite shared 80% nt identity with Tomato leaf curl Cameroon alphasatellite (ToLCCMA), and the new alphasatellite species is herein named Ageratum leaf curl Cameroon alphasatellite (ALCCMA). In addition, two fragments containing begomovirus-alphasatellite sequences were cloned from sample AGLI4, and they were related to the defecting interfering molecule (Y14167) associated with Ageratum yellow vein virus from Asia. These results suggest that the begomoviral-satellite complexes infecting A. conyzoides in Cameroon may be as complex or more so, to species and strains reported thus far from Asia. © 2011 Elsevier B.V.
• Leke, W. N., Brown, J. K., Ligthart, M. E., Sattar, N., Njualem, D. K., & Kvarnheden, A. (2012). Ageratum conyzoides: A host to a unique begomovirus disease complex in Cameroon. Virus Research, 163(Issue 1). doi:10.1016/j.virusres.2011.09.039
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  Ageratum conyzoides (goat weed) is a widespread uncultivated species in Cameroon that exhibits leaf curl disease (LCD) symptoms suggestive of begomovirus infection. In Asia, different begomovirus-satellite complexes have been identified in A. conyzoides. The objective of this study was to determine the identity of the suspect begomoviruses and their associated satellites in A. conyzoides in Cameroon. The results indicated that all three symptomatic A. conyzoides plants examined were infected with a new begomovirus species, herein named Ageratum leaf curl Cameroon virus (ALCCMV). The ALCCMV genome sequences shared their highest identity, at 84.3-88.5%, with a group of tomato-infecting begomoviruses from West Africa. In addition, a betasatellite and an alphasatellite were cloned from the same symptomatic A. conyzoides plants. The betasatellite sequences shared limited sequence identity at 37% or less with the betasatellite Cotton leaf curl Gezira betasatellite, and the new betasatellite species is herein named Ageratum leaf curl Cameroon betasatellite (ALCCMB). The alphasatellite shared 80% nt identity with Tomato leaf curl Cameroon alphasatellite (ToLCCMA), and the new alphasatellite species is herein named Ageratum leaf curl Cameroon alphasatellite (ALCCMA). In addition, two fragments containing begomovirus-alphasatellite sequences were cloned from sample AGLI4, and they were related to the defecting interfering molecule (Y14167) associated with Ageratum yellow vein virus from Asia. These results suggest that the begomoviral-satellite complexes infecting A. conyzoides in Cameroon may be as complex or more so, to species and strains reported thus far from Asia. © 2011 Elsevier B.V.
• Pan, H., Chu, D., Yan, W., Qi, S. u., Liu, B., Wang, S., Qingjun, W. u., Xie, W., Jiao, X., Rumei, L. i., Yang, N., Yang, X., Baoyun, X. u., Brown, J. K., Zhou, X., & Zhang, Y. (2012). Rapid spread of tomato yellow leaf curl virus in china is aided differentially by two invasive whiteflies. PLoS ONE, 7(4).
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  PMID: 22514670;PMCID: PMC3325912;Abstract: Background: Tomato yellow leaf curl virus (TYLCV) was introduced into China in 2006, approximately 10 years after the introduction of an invasive whitefly, Bemisia tabaci (Genn.) B biotype. Even so the distribution and prevalence of TYLCV remained limited, and the economic damage was minimal. Following the introduction of Q biotype into China in 2003, the prevalence and spread of TYLCV started to accelerate. This has lead to the hypothesis that the two biotypes might not be equally competent vectors of TYLCV. Methodology/Principal Findings: The infection frequency of TYLCV in the field-collected B. tabaci populations was investigated, the acquisition and transmission capability of TYLCV by B and Q biotypes were compared under the laboratory conditions. Analysis of B. tabaci populations from 55 field sites revealed the existence of 12 B and 43 Q biotypes across 18 provinces in China. The acquisition and transmission experiments showed that both B and Q biotypes can acquire and transmit the virus, however, Q biotype demonstrated superior acquisition and transmission capability than its B counterparts. Specifically, Q biotype acquired significantly more viral DNA than the B biotype, and reached the maximum viral load in a substantially shorter period of time. Although TYLCV was shown to be transmitted horizontally by both biotypes, Q biotype exhibited significantly higher viral transmission frequency than B biotype. Vertical transmission result, on the other hand, indicated that TYLCV DNA can be detected in eggs and nymphs, but not in pupae and adults of the first generation progeny. Conclusions/Significance: These combined results suggested that the epidemiology of TYLCV was aided differentially by the two invasive whiteflies (B and Q biotypes) through horizontal but not vertical transmission of the virus. This is consistent with the concomitant eruption of TYLCV in tomato fields following the recent rapid invasion of Q biotype whitefly in China. © 2012 Pan et al.
• Pan, H., Chu, D., Yan, W., Su, Q., Liu, B., Wang, S., Wu, Q., Xie, W., Jiao, X., Li, R., Yang, N., Yang, X., Xu, B., Brown, J. K., Zhou, X., & Zhang, Y. (2012). Rapid spread of tomato yellow leaf curl virus in china is aided differentially by two invasive whiteflies. PLoS ONE, 7(Issue 4). doi:10.1371/journal.pone.0034817
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  Background: Tomato yellow leaf curl virus (TYLCV) was introduced into China in 2006, approximately 10 years after the introduction of an invasive whitefly, Bemisia tabaci (Genn.) B biotype. Even so the distribution and prevalence of TYLCV remained limited, and the economic damage was minimal. Following the introduction of Q biotype into China in 2003, the prevalence and spread of TYLCV started to accelerate. This has lead to the hypothesis that the two biotypes might not be equally competent vectors of TYLCV. Methodology/Principal Findings: The infection frequency of TYLCV in the field-collected B. tabaci populations was investigated, the acquisition and transmission capability of TYLCV by B and Q biotypes were compared under the laboratory conditions. Analysis of B. tabaci populations from 55 field sites revealed the existence of 12 B and 43 Q biotypes across 18 provinces in China. The acquisition and transmission experiments showed that both B and Q biotypes can acquire and transmit the virus, however, Q biotype demonstrated superior acquisition and transmission capability than its B counterparts. Specifically, Q biotype acquired significantly more viral DNA than the B biotype, and reached the maximum viral load in a substantially shorter period of time. Although TYLCV was shown to be transmitted horizontally by both biotypes, Q biotype exhibited significantly higher viral transmission frequency than B biotype. Vertical transmission result, on the other hand, indicated that TYLCV DNA can be detected in eggs and nymphs, but not in pupae and adults of the first generation progeny. Conclusions/Significance: These combined results suggested that the epidemiology of TYLCV was aided differentially by the two invasive whiteflies (B and Q biotypes) through horizontal but not vertical transmission of the virus. This is consistent with the concomitant eruption of TYLCV in tomato fields following the recent rapid invasion of Q biotype whitefly in China. © 2012 Pan et al.
• Pan, H., Chu, D., Yan, W., Su, Q., Liu, B., Wang, S., Wu, Q., Xie, W., Jiao, X., Li, R., Yang, N., Yang, X., Xu, B., Brown, J., Zhou, X., & Zhang, Y. (2012). Rapid spread of Tomato yellow leaf curl virus in China is aided differentially by two invasive whitefly biotypes. PLoS ONE, 7(4).
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  e34817. doi:10.1371/.
• Popovski, S., Kollenberg, M., Gorovitz, R., Brown, J., Cicero, J., Czosnek, H., Winter, S., & Ghanim, M. (2012). Implication of Bemisia tabaci heat shock protein 70 in begomovirus - whitefly interactions. J. Virol, 86, 13241-13252.
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  doi:10.1128/JVI.00880-12.
• Brown, J. K., Mills-Lujan, K., & Idris, A. M. (2011). Phylogenetic analysis of Melon chlorotic leaf curl virus from Guatemala: Another emergent species in the Squash leaf curl virus clade. Virus Research, 158(1-2), 257-262.
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  PMID: 21420452;Abstract: The genome of a new bipartite begomovirus Melon chlorotic leaf curl virus from Guatemala (MCLCuV-GT) was cloned and the genome sequence was determined. The virus causes distinct symptoms on melons that were not previously observed in melon crops in Guatemala or elsewhere. Phylogenetic analysis of MCLCuV-GT and begomoviruses infecting cucurbits and other host plant species indicated that its closest relative was MCLCuV from Costa Rica (MCLCuV-CR). The DNA-A components of two isolates shared 88.8% nucleotide identity, making them strains of the same species. Further, both MCLCuV-GT and MCLCuV-CR grouped with other Western Hemisphere cucurbit-infecting species in the SLCV-clade making them the most southerly cucurbit-infecting members of the clade to date. Although the common region of the cognate components of MCLCuV-GT and MCLCuV-CR, shared ∼96.3% nucleotide identity. While DNA-A and DNA-B components of MCLCuV-GT were less than 86% nucleotide identity with the respective DNA-A and DNA-B common regions of MCLCuV-CR. The late viral genes of the two strains shared the least nt identity (90%). The collective evidence suggests that these two strains of MCLCuV are evolutionarily divergent owing in part to recombination, but also due to the accumulation of a substantial number of mutations. In addition they are differentially host-adapted, as has been documented for other cucurbit-infecting, bean-adapted, species in the SLCV clade. © 2011 Elsevier B.V.
• Brown, J. K., Mills-Lujan, K., & Idris, A. M. (2011). Phylogenetic analysis of Melon chlorotic leaf curl virus from Guatemala: Another emergent species in the Squash leaf curl virus clade. Virus Research, 158(Issue 1-2). doi:10.1016/j.virusres.2011.03.002
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  The genome of a new bipartite begomovirus Melon chlorotic leaf curl virus from Guatemala (MCLCuV-GT) was cloned and the genome sequence was determined. The virus causes distinct symptoms on melons that were not previously observed in melon crops in Guatemala or elsewhere. Phylogenetic analysis of MCLCuV-GT and begomoviruses infecting cucurbits and other host plant species indicated that its closest relative was MCLCuV from Costa Rica (MCLCuV-CR). The DNA-A components of two isolates shared 88.8% nucleotide identity, making them strains of the same species. Further, both MCLCuV-GT and MCLCuV-CR grouped with other Western Hemisphere cucurbit-infecting species in the SLCV-clade making them the most southerly cucurbit-infecting members of the clade to date. Although the common region of the cognate components of MCLCuV-GT and MCLCuV-CR, shared ∼96.3% nucleotide identity. While DNA-A and DNA-B components of MCLCuV-GT were less than 86% nucleotide identity with the respective DNA-A and DNA-B common regions of MCLCuV-CR. The late viral genes of the two strains shared the least nt identity (90%). The collective evidence suggests that these two strains of MCLCuV are evolutionarily divergent owing in part to recombination, but also due to the accumulation of a substantial number of mutations. In addition they are differentially host-adapted, as has been documented for other cucurbit-infecting, bean-adapted, species in the SLCV clade. © 2011 Elsevier B.V.
• Brown, J., Mills-Lujan, K., & Idris, A. (2011). Phylogenetic analysis of Melon chlorotic leaf curl virus from Guatemala, another emergent species in the Squash leaf curl virus clade. Virus Res, 158, 257-262.
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  doi:10.1016/j.virusres.2011.03.002.
• Cicero, J. M., & Brown, J. K. (2011). Anatomy of accessory salivary glands of the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) and correlations to begomovirus transmission. Annals of the Entomological Society of America, 104(2), 280-286.
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  Abstract: Visualization of dissected accessory salivary glands (ASGs) of the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) by light microscopy (LM) revealed three distinctive toluidine blue O stain profiles. Considered morphotypes, the three profiles are hypothesized to represent stages of a salivation cycle, wherein contents are cyclically depleted and subsequently regenerated as needed for feeding. When whiteflies were repeatedly interrupted during their initial feeding behaviors, and then ASGs were dissected, a fourth stain profile was revealed. These observations are therefore relevant to the different mechanisms involved in whitefly-mediated virus transmission to plants. Stain techniques involved in transmission electron microscopy of extirpated and nonextirpated ASGs reveal entirely different profiles that cannot yet be correlated to LM findings. The midgut of B. tabaci is capable of transposing its location from the abdomen to the thorax and can come into direct contact with the ASGs. This finding opens new lines of thought in the potential for interaction between the two, such as purging of excess water and waste, and virus transmission. © 2011 Entomological Society of America.
• Cicero, J. M., & Brown, J. K. (2011). Anatomy of accessory salivary glands of the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) and correlations to begomovirus transmission. Annals of the Entomological Society of America, 104(Issue 2). doi:10.1603/an10171
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  Visualization of dissected accessory salivary glands (ASGs) of the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) by light microscopy (LM) revealed three distinctive toluidine blue O stain profiles. Considered morphotypes, the three profiles are hypothesized to represent stages of a salivation cycle, wherein contents are cyclically depleted and subsequently regenerated as needed for feeding. When whiteflies were repeatedly interrupted during their initial feeding behaviors, and then ASGs were dissected, a fourth stain profile was revealed. These observations are therefore relevant to the different mechanisms involved in whitefly-mediated virus transmission to plants. Stain techniques involved in transmission electron microscopy of extirpated and nonextirpated ASGs reveal entirely different profiles that cannot yet be correlated to LM findings. The midgut of B. tabaci is capable of transposing its location from the abdomen to the thorax and can come into direct contact with the ASGs. This finding opens new lines of thought in the potential for interaction between the two, such as purging of excess water and waste, and virus transmission. © 2011 Entomological Society of America.
• Cicero, J. M., & Brown, J. K. (2011). Functional anatomy of whitefly organs associated with Squash leaf curl virus (Geminiviridae: Begomovirus) transmission by the B biotype of Bemisia tabaci (Hemiptera: Aleyrodidae). Annals of the Entomological Society of America, 104(2), 261-279.
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  Abstract: The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is a sibling species group that transmits Squash leaf curl virus (SLCV) and other geminiviruses (Geminiviridae, genus Begomovirus) in a circulative and persistent manner. Using in situ hybridization, SLCV was localized in the primary salivary glands, the midgut, and the filter chamber of adults of the B biotype in the group. However, no SLCV particles were localized in the accessory salivary glands. The midgut loop was found to reside, fully or partially, in the abdomen or thorax in >8,000 dissections, indicating that it is capable of moving through the petiole, a constriction between the two body sections. When extended to its anterior-most position in the thorax, the midgut can make direct contact with the salivary glands, but evidence for direct transfer of virions is lacking. However, the widely presumed pathway of viral transport from the gut to the whitefly primary salivary glands can now be broadened to include both the blood and the possibility of direct transfer during contiguity of these two organs. Light microscopical observations indicated that the primary salivary gland consists of a central region flanked by two dark-staining regions, referred to as endcaps. Electron microscopical examination of extirpated and nonextirpated primary salivary glands revealed additional distinct regions and cell types. One such region, located between the central region and an endcap, was correlated directly to the region where virions have previously been immunolocalized. © 2011 Entomological Society of America.
• Cicero, J. M., & Brown, J. K. (2011). Functional anatomy of whitefly organs associated with Squash leaf curl virus (Geminiviridae: Begomovirus) transmission by the B biotype of Bemisia tabaci (Hemiptera: Aleyrodidae). Annals of the Entomological Society of America, 104(Issue 2). doi:10.1603/an10075
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  The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is a sibling species group that transmits Squash leaf curl virus (SLCV) and other geminiviruses (Geminiviridae, genus Begomovirus) in a circulative and persistent manner. Using in situ hybridization, SLCV was localized in the primary salivary glands, the midgut, and the filter chamber of adults of the B biotype in the group. However, no SLCV particles were localized in the accessory salivary glands. The midgut loop was found to reside, fully or partially, in the abdomen or thorax in >8,000 dissections, indicating that it is capable of moving through the petiole, a constriction between the two body sections. When extended to its anterior-most position in the thorax, the midgut can make direct contact with the salivary glands, but evidence for direct transfer of virions is lacking. However, the widely presumed pathway of viral transport from the gut to the whitefly primary salivary glands can now be broadened to include both the blood and the possibility of direct transfer during contiguity of these two organs. Light microscopical observations indicated that the primary salivary gland consists of a central region flanked by two dark-staining regions, referred to as endcaps. Electron microscopical examination of extirpated and nonextirpated primary salivary glands revealed additional distinct regions and cell types. One such region, located between the central region and an endcap, was correlated directly to the region where virions have previously been immunolocalized. © 2011 Entomological Society of America.
• Cicero, J., & Brown, J. (2011). Functional anatomy of whitefly organs associated with Squash leaf curl virus (Geminiviridae: Begomovirus) transmission by the B Biotype of Bemisia tabaci (Aleyrodidae: Hemiptera). Ann. Entomol. Soc. Am, 104, 261-279.
• Cicero, J., & Brown, J. (2011). The anatomy of the accessory salivary glands of the whitefly Bemisia tabaci (Aleyrodidae: Hemiptera), and correlations to begomovirus transmission. Ann. Entomol. Soc. Am, 104, 261-279.
• Gu, Q. S., Liu, Y. H., Wang, Y. H., Huangfu, W. G., Gu, H. F., Xu, L., Song, F. M., & Brown, J. K. (2011). First report of Cucurbit chlorotic yellows virus in cucumber, melon, and watermelon in China. Plant Disease, 95(1), 73-.
• Gu, Q. S., Liu, Y. H., Wang, Y. H., Huangfu, W. G., Gu, H. F., Xu, L., Song, F. M., & Brown, J. K. (2011). First report of Cucurbit chlorotic yellows virus in cucumber, melon, and watermelon in China. Plant Disease, 95(Issue 1). doi:10.1094/pdis-07-10-0550
• Idris, A. M., Shahid, M. S., Briddon, R. W., Khan, A. J., Zhu, J. -., & Brown, J. K. (2011). An unusual alphasatellite associated with monopartite begomoviruses attenuates symptoms and reduces betasatellite accumulation. Journal of General Virology, 92(3), 706-717.
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  PMID: 21084498;Abstract: The Oman strain of Tomato yellow leaf curl virus (TYLCV-OM) and its associated betasatellite, an isolate of Tomato leaf curl betasatellite (ToLCB), were previously reported from Oman. Here we report the isolation of a second, previously undescribed, begomovirus [Tomato leaf curl Oman virus (ToLCOMV)] and an alphasatellite from that same plant sample. This alphasatellite is closely related (90% shared nucleotide identity) to an unusual DNA-2-type Ageratum yellow vein Singapore alphasatellite (AYVSGA), thus far identified only in Singapore. ToLCOMV was found to have a recombinant genome comprising sequences derived from two extant parents, TYLCV-OM, which is indigenous to Oman, and Papaya leaf curl virus from the Indian subcontinent. All possible combinations of ToLCOMV, TYLCV-OM, ToLCB and AYVSGA were used to agro-inoculate tomato and Nicotiana benthamiana. Infection with ToLCOMV yielded mild leaf-curl symptoms in both hosts; however, plants inoculated with TYLCV-OM developed more severe symptoms. Plants infected with ToLCB in the presence of either helper begomovirus resulted in more severe symptoms. Surprisingly, symptoms in N. benthamiana infected with the alphasatellite together with either of the helper viruses and the betasatellite were attenuated and betasatellite DNA accumulation was substantially reduced. However, in the latter plants no concomitant reduction in the accumulation of helper virus DNA was observed. This is the first example of an attenuation of begomovirus-betasatellite symptoms by this unusual class of alphasatellites. This observation suggests that some DNA-2 alphasatellites encode a pathogenicity determinant that may modulate begomovirus-betasatellite infection by reducing betasatellite DNA accumulation. © 2011 SGM.
• Idris, A. M., Shahid, M. S., Briddon, R. W., Khan, A. J., Zhu, J. K., & Brown, J. K. (2011). An unusual alphasatellite associated with monopartite begomoviruses attenuates symptoms and reduces betasatellite accumulation. Journal of General Virology, 92(Issue 3). doi:10.1099/vir.0.025288-0
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  The Oman strain of Tomato yellow leaf curl virus (TYLCV-OM) and its associated betasatellite, an isolate of Tomato leaf curl betasatellite (ToLCB), were previously reported from Oman. Here we report the isolation of a second, previously undescribed, begomovirus [Tomato leaf curl Oman virus (ToLCOMV)] and an alphasatellite from that same plant sample. This alphasatellite is closely related (90% shared nucleotide identity) to an unusual DNA-2-type Ageratum yellow vein Singapore alphasatellite (AYVSGA), thus far identified only in Singapore. ToLCOMV was found to have a recombinant genome comprising sequences derived from two extant parents, TYLCV-OM, which is indigenous to Oman, and Papaya leaf curl virus from the Indian subcontinent. All possible combinations of ToLCOMV, TYLCV-OM, ToLCB and AYVSGA were used to agro-inoculate tomato and Nicotiana benthamiana. Infection with ToLCOMV yielded mild leaf-curl symptoms in both hosts; however, plants inoculated with TYLCV-OM developed more severe symptoms. Plants infected with ToLCB in the presence of either helper begomovirus resulted in more severe symptoms. Surprisingly, symptoms in N. benthamiana infected with the alphasatellite together with either of the helper viruses and the betasatellite were attenuated and betasatellite DNA accumulation was substantially reduced. However, in the latter plants no concomitant reduction in the accumulation of helper virus DNA was observed. This is the first example of an attenuation of begomovirus-betasatellite symptoms by this unusual class of alphasatellites. This observation suggests that some DNA-2 alphasatellites encode a pathogenicity determinant that may modulate begomovirus-betasatellite infection by reducing betasatellite DNA accumulation. © 2011 SGM.
• Idris, A., Shahid, M., Briddon, R., Khan, A., Zhu, J., & Brown, J. (2011). An unusual alphasatellite associated with monopartite begomoviruses attenuates symptoms and reduces betasatellite accumulation. J Gen Virol, 92, 706-717.
• Leke, W. N., Kvarnheden, A., Ngane, E. B., Titanji, V. P., & Brown, J. K. (2011). Molecular characterization of a new begomovirus and divergent alphasatellite from tomato in Cameroon. Archives of Virology, 156(5), 925-928.
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  PMID: 21394606;
• Leke, W. N., Kvarnheden, A., Ngane, E. B., Titanji, V. P., & Brown, J. K. (2011). Molecular characterization of a new begomovirus and divergent alphasatellite from tomato in Cameroon. Archives of Virology, 156(Issue 5). doi:10.1007/s00705-011-0957-4
• Leke, W., Brown, J., Ligthart, M., Sattar, N., Njualem, D., & Kvarnheden, A. (2011). Ageratum conyzoides: a host to a unique begomovirus disease complex in Cameroon. Virus Res, 163, 229-237.
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  201x. ; doi:10.1016/j.virusres.2011.09.039.
• Leke, W., Kvarnheden, A., Ngane, E., Titanji, V., & Brown, J. (2011). Molecular characterization of a new begomovirus and divergent alphasatellite from tomato in Cameroon. Arch. Virol, 156, 925-928.
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  [DOI 10.1007/s00705-011-0957-4].
• Papayiannis, L. C., Katis, N. I., Idris, A. M., & Brown, J. K. (2011). Identification of weed hosts of Tomato yellow leaf curl virus in Cyprus. Plant Disease, 95(2), 120-125.
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  Abstract: An extensive study was conducted during 2007 and 2008 in three major tomato production areas of Cyprus, where Tomato yellow leaf curl virus (TYLCV) is commonly found, to assess the incidence and prevalence of naturally infected weed species that could serve as TYLCV reservoirs. Approximately 4,000 of the most common dicotyledonous plants belonging to 122 species from 25 families were collected, identified, and tested for TYLCV presence using serological and molecular methods. The tests included a previously reported conventional polymerase chain reaction (PCR) assay and a real-time TaqMan PCR assay developed and optimized in this study. Real-time PCR was found to be the most sensitive technique, and enabled the detection of TYLCV in 461 samples of 49 different species belonging to the families Amaranthaceae, Chenopodiaceae, Compositae, Convolvulaceae, Cruciferae, Euphorbiaceae, Geraniaceae, Leguminosae, Malvaceae, Orobanchaceae, Plantaginaceae, Primulaceae, Solanaceae, Umbelliferae, and Urticaceae. The results further indicated that the host range of TYLCV in Cyprus is far more extensive than previously documented and, therefore, new management strategies are required. These should focus on the control of alternative virus hosts during the growing season and in crop-free periods. © 2011 The American Phytopathological Society.
• Papayiannis, L. C., Katis, N. I., Idris, A. M., & Brown, J. K. (2011). Identification of weed hosts of Tomato yellow leaf curl virus in Cyprus. Plant Disease, 95(Issue 2). doi:10.1094/pdis-05-10-0346
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  An extensive study was conducted during 2007 and 2008 in three major tomato production areas of Cyprus, where Tomato yellow leaf curl virus (TYLCV) is commonly found, to assess the incidence and prevalence of naturally infected weed species that could serve as TYLCV reservoirs. Approximately 4,000 of the most common dicotyledonous plants belonging to 122 species from 25 families were collected, identified, and tested for TYLCV presence using serological and molecular methods. The tests included a previously reported conventional polymerase chain reaction (PCR) assay and a real-time TaqMan PCR assay developed and optimized in this study. Real-time PCR was found to be the most sensitive technique, and enabled the detection of TYLCV in 461 samples of 49 different species belonging to the families Amaranthaceae, Chenopodiaceae, Compositae, Convolvulaceae, Cruciferae, Euphorbiaceae, Geraniaceae, Leguminosae, Malvaceae, Orobanchaceae, Plantaginaceae, Primulaceae, Solanaceae, Umbelliferae, and Urticaceae. The results further indicated that the host range of TYLCV in Cyprus is far more extensive than previously documented and, therefore, new management strategies are required. These should focus on the control of alternative virus hosts during the growing season and in crop-free periods. © 2011 The American Phytopathological Society.
• Brown, J. K., Byrne, F. J., Degain, B. A., Dennehy, T. J., Fabrick, J. A., Harpold, V. S., Li, X., Morin, S., Nichols, R. L., & Zaborac, M. (2010). Extraordinary resistance to insecticides reveals exotic Q biotype of Bemisia tabaci in the New World.. Journal of economic entomology, 103(6), 2174-86. doi:10.1603/ec10239
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  A strain of the whitefly Bemisia tabaci (Gennadius) possessing unusually high levels of resistance to a wide range of insecticides was discovered in 2004 in the course of routine resistance monitoring in Arizona. The multiply resistant insects, collected from poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) plants purchased at a retail store in Tucson, were subjected to biotype analysis in three laboratories. Polyacrylamide gel electrophoresis of naphthyl esterases and sequencing of the mitochondrial cytochrome oxidase I gene (780 bp) confirmed the first detection of the Q biotype of B. tabaci in the New World. This U.S. Q biotype strain, referred to as Poinsettia'04, was highly resistant to two selective insect growth regulators, pyriproxyfen and buprofezin, and to mixtures of fenpropathrin and acephate. It was also unusually low in susceptibility to the neonicotinoid insecticides imidacloprid, acetamiprid, and thiamethoxam, relative to B biotype whiteflies. In 100 collections of whiteflies made in Arizona cotton (Gossypium spp.), vegetable, and melon (Cucumis melo L.) fields from 2001 to 2005, no Q biotypes were detected. Regions of the United States that were severely impacted by the introduction of the B biotype of B. tabaci in the 1980s would be well advised to promote measures that limit movement of the Q biotype from controlled environments into field systems and to formulate alternatives for managing this multiply-resistant biotype, in the event that it becomes more widely distributed.
• Brown, J. K., Rehman, M., Rogan, D., Martin, R. R., & Idris, A. M. (2010). First report of "candidatus liberibacter psyllaurous" (synonym "ca. l. solanacearum") associated with 'tomato vein-greening' and 'tomato psyllid yellows' diseases in commercial greenhouses in Arizona. Plant Disease, 94(3), 376-.
• Chu, D., Wan, F. H., Zhang, Y. J., & Brown, J. K. (2010). Change in the biotype composition of bemisia tabaci in Shandong Province of China from 2005 to 2008. Environmental Entomology, 39(3), 1028-1036.
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  PMID: 20550819;Abstract: Certain biotypes of the Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) complex cause extensive damage and are important pests and virus vectors in agricultural crops throughout the world. Among the most invasive and well studied are the B and Q biotypes. Recent reports in Shandong Province, China, have indicated that the Q biotype was introduced there in ≈ 2005, whereas the B biotype has been established there for ∼10 yr. Even so, the present distribution of the two biotypes in Shandong has not been examined. The results of this study showed that the B and Q biotypes are both present in Shandong Province based on bar-coding using a ≈450-base fragment of the mitochondrial cytochrome oxidase I (mtCOI) gene. In addition, a B biotype-specific polymerase chain reaction primer pair that amplifies a ≈300 bp mtCOI fragment was designed and used to examine the biotype composition of B. tabaci in selected crops from six provincial locations, using the general mtCOI primers as an internal positive control for DNA quality. The results of this study indicated that the Q biotype was the predominant B. tabaci colonizing all of the crops in the study sites examined. This suggests that the Q biotype has displaced the B biotype in Shandong Province of China, which until now was the predominant biotype. This is the first report of the displacement of the B by the Q biotype in field grown crops in China, and in a locale where neither the B nor the Q biotype is native. We hypothesize that this phenomenon may have been exacerbated by the widespread use of neonicotinoid insecticides for whitefly control, given the sustained efficacy thus far of neonicotinoids against the B biotype, and their failure at times to effectively control the Q biotype. © 2010 Entomological Society of America.
• Chu, D., Wan, F. H., Zhang, Y. J., & Brown, J. K. (2010). Change in the biotype composition of bemisia tabaci in Shandong Province of China from 2005 to 2008. Environmental Entomology, 39(Issue 3). doi:10.1603/en09161
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  Certain biotypes of the Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) complex cause extensive damage and are important pests and virus vectors in agricultural crops throughout the world. Among the most invasive and well studied are the B and Q biotypes. Recent reports in Shandong Province, China, have indicated that the Q biotype was introduced there in ≈ 2005, whereas the B biotype has been established there for ∼10 yr. Even so, the present distribution of the two biotypes in Shandong has not been examined. The results of this study showed that the B and Q biotypes are both present in Shandong Province based on bar-coding using a ≈450-base fragment of the mitochondrial cytochrome oxidase I (mtCOI) gene. In addition, a B biotype-specific polymerase chain reaction primer pair that amplifies a ≈300 bp mtCOI fragment was designed and used to examine the biotype composition of B. tabaci in selected crops from six provincial locations, using the general mtCOI primers as an internal positive control for DNA quality. The results of this study indicated that the Q biotype was the predominant B. tabaci colonizing all of the crops in the study sites examined. This suggests that the Q biotype has displaced the B biotype in Shandong Province of China, which until now was the predominant biotype. This is the first report of the displacement of the B by the Q biotype in field grown crops in China, and in a locale where neither the B nor the Q biotype is native. We hypothesize that this phenomenon may have been exacerbated by the widespread use of neonicotinoid insecticides for whitefly control, given the sustained efficacy thus far of neonicotinoids against the B biotype, and their failure at times to effectively control the Q biotype. © 2010 Entomological Society of America.
• Collins, A., Rehman, M. M., Chowda-Reddy, R. V., Wang, A., Fondong, V., Brown, J., & Roye, M. (2010). Molecular characterization and experimental host range of an isolate of Macroptilium golden mosaic virus that infects Wissadula amplissima in Jamaica. Virus Research, 150(Issue 1-2). doi:10.1016/j.virusres.2010.03.008
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  Partial genome sequences for the tentative begomovirus Macroptilium golden mosaic virus (MGMV) have been previously reported and were originally obtained for an isolate that infected Macroptilium lathyroides in Jamaica. In this study, we PCR-amplified, cloned and determined the sequence for the complete genome of isolates of MGMV that we found infecting Wissadula amplissima collected from August Town and Spanish Town, Jamaica. Sequence analysis confirmed that MGMV is a distinct begomovirus species, based on the ICTV 89% rule for species demarcation. MGMV shared its highest nucleotide identity at 79% for DNA-A component and 66% for DNA-B component to Corchorus yellow spot virus [Mexico:Yucatan:2005]. The names Macroptilium golden mosaic virus [Jamaica1:Wissadula:AugustTown] (MGMV [JM1:Wd:AT]) and Macroptilium golden mosaic virus [Jamaica1:Wissadula:SpanishTown] (MGMV [JM1:Wd:ST]) are proposed herein for the MGMV isolates from August Town and Spanish Town, respectively. The genome organization of MGMV [JM1:Wd:AT] and MGMV [JM1:Wd:ST] is characteristic of Western Hemisphere bipartite begomoviruses. Excluding the replication enhancer protein (REn), all proteins encoded by the MGMV [JM1:Wd:AT] and MGMV [JM1:Wd:ST] genomes are most similar to their counterparts in Western Hemisphere begomoviruses. The REn proteins of MGMV [JM1:Wd:AT] and MGMV [JM1:Wd:ST], share greatest similarity to the REn protein of Corchorus yellow vein virus [Vietnam:Hoa Binh:2000], a New World-like begomovirus identified in Asia. Phylogenetic reconstruction places MGMV in a clade containing Potato yellow mosaic virus. Results of an experimental host range study indicated that MGMV [JM1:Wd:AT] can infect kidney bean, hot pepper and tomato. © 2010 Elsevier B.V.
• Collins, A., Rehman, M. M., Chowda-Reddy, R., Wang, A., Fondong, V., Brown, J., & Roye, M. (2010). Molecular characterization and experimental host range of an isolate of Macroptilium golden mosaic virus that infects Wissadula amplissima in Jamaica. Virus Research, 150(1-2), 148-152.
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  PMID: 20347895;Abstract: Partial genome sequences for the tentative begomovirus Macroptilium golden mosaic virus (MGMV) have been previously reported and were originally obtained for an isolate that infected Macroptilium lathyroides in Jamaica. In this study, we PCR-amplified, cloned and determined the sequence for the complete genome of isolates of MGMV that we found infecting Wissadula amplissima collected from August Town and Spanish Town, Jamaica. Sequence analysis confirmed that MGMV is a distinct begomovirus species, based on the ICTV 89% rule for species demarcation. MGMV shared its highest nucleotide identity at 79% for DNA-A component and 66% for DNA-B component to Corchorus yellow spot virus [Mexico:Yucatan:2005]. The names Macroptilium golden mosaic virus [Jamaica1:Wissadula:AugustTown] (MGMV [JM1:Wd:AT]) and Macroptilium golden mosaic virus [Jamaica1:Wissadula:SpanishTown] (MGMV [JM1:Wd:ST]) are proposed herein for the MGMV isolates from August Town and Spanish Town, respectively. The genome organization of MGMV [JM1:Wd:AT] and MGMV [JM1:Wd:ST] is characteristic of Western Hemisphere bipartite begomoviruses. Excluding the replication enhancer protein (REn), all proteins encoded by the MGMV [JM1:Wd:AT] and MGMV [JM1:Wd:ST] genomes are most similar to their counterparts in Western Hemisphere begomoviruses. The REn proteins of MGMV [JM1:Wd:AT] and MGMV [JM1:Wd:ST], share greatest similarity to the REn protein of Corchorus yellow vein virus [Vietnam:Hoa Binh:2000], a New World-like begomovirus identified in Asia. Phylogenetic reconstruction places MGMV in a clade containing Potato yellow mosaic virus. Results of an experimental host range study indicated that MGMV [JM1:Wd:AT] can infect kidney bean, hot pepper and tomato. © 2010 Elsevier B.V.
• Crosslin, J. M., Munyaneza, J. E., Liefting, L., Crosslin, J. M., & Brown, J. K. (2010). A History in the Making: Potato Zebra Chip Disease Associated with a New Psyllid-borne Bacterium. A Tale of Striped Potatoes. APSnet Feature Articles. doi:10.1094/apsnetfeature-2010-0110
• Dennehy, T., Degain, B., Harpold, V., Zaborac, M., Morin, S., Fabrick, J., Nichols, R., Brown, J., Byrne, F., & Li, X. (2010). Extraordinary resistance to insecticides reveals exotic Q biotype of Bemisia tabaci in the New World. Journal of Economic Entomology, 103(6), 2174-2186. doi:10.1603/EC10239
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  A strain of the whitefly Bemisia tabaci (Gennadius) possessing unusually high levels of resistance to a wide range of insecticides was discovered in 2004 in the course of routine resistance monitoring in Arizona. The multiply resistant insects, collected from poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) plants purchased at a retail store in Tucson, were subjected to biotype analysis in three laboratories. Polyacrylamide gel electrophoresis of naphthyl esterases and sequencing of the mitochondrial cytochrome oxidase I gene (780 bp) confirmed the first detection of the Q biotype of B. tabaci in the New World. This U.S. Q biotype strain, referred to as Poinsettia'04, was highly resistant to two selective insect growth regulators, pyriproxyfen and buprofezin, and to mixtures of fenpropathrin and acephate. It was also unusually low in susceptibility to the neonicotinoid insecticides imidacloprid, acetamiprid, and thiamethoxam, relative to B biotype whiteflies. In 100 collections of whiteflies made in Arizona cotton (Gossypium spp.), vegetable, and melon (Cucumis melo L.) fields from 2001 to 2005, no Q biotypes were detected. Regions of the United States that were severely impacted by the introduction of the B biotype of B. tabaci in the 1980s would be well advised to promote measures that limit movement of the Q biotype from controlled environments into field systems and to formulate alternatives for managing this multiply-resistant biotype, in the event that it becomes more widely distributed.
• Hernandez, C., & Brown, J. K. (2010). First report of a new curtovirus species, Spinach severe curly top virus, in commercial Spinach plants (Spinacia oleracea) from South-Central Arizona. Plant Disease, 94(7), 917-.
• Hernandez, C., & Brown, J. K. (2010). First report of a new curtovirus species, Spinach severe curly top virus, in commercial Spinach plants (Spinacia oleracea) from South-Central Arizona. Plant Disease, 94(Issue 7). doi:10.1094/pdis-94-7-0917b
• Hernandez-Zepeda, C., Isakeit, T., Scott Jr., A., & Brown, J. K. (2010). First report of okra yellow mosaic Mexico virus in okra in the United States. Plant Disease, 94(7), 924-.
• Hernandez-Zepeda, C., Isakeit, T., Scott, A., & Brown, J. K. (2010). First report of okra yellow mosaic Mexico virus in okra in the United States. Plant Disease, 94(Issue 7). doi:10.1094/pdis-94-7-0924b
• Hernández-Zepeda, C., Brown, J. K., Moreno-Valenzuela, O. A., Argüello-Astorga, G., Idris, A. M., Carnevali, G., & Rivera-Bustamante, R. F. (2010). Characterization of Rhynchosia yellow mosaic Yucatan virus, a new recombinant begomovirus associated with two fabaceous weeds in Yucatan, Mexico. Archives of Virology, 155(Issue 10). doi:10.1007/s00705-010-0730-0
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  Rhynchosia minima (L.) DC. (Fabaceae) plants exhibiting bright golden mosaic symptoms were previously associated with begomovirus infection in Yucatan, México [1]. To characterize the begomovirus infecting these plants, the complete bipartite genome was cloned and sequenced. Sequence comparisons indicated that the virus was distinct from all other begomoviruses known to date, including those previously identified from symptomatic R. minima, and the name Rhynchosia yellow mosaic Yucatan virus (RhYMYuV) is proposed. Pairwise comparisons indicated that RhYMYuV DNA-A [2,597 nt, (EU021216)] and DNA-B [2,542 nt, (FJ792608)] components shared the highest nt sequence identity with Cabbage leaf curl virus (CaLCuV), 87% for component A and 71% for component B. Phylogenetic analysis indicated that both components of RhYMYuV are most closely related to other New World begomoviruses, having as closest relatives immediate outliers to the major Squash leaf curl virus (SLCV) clade. Recombination analysis of the RhYMYuV genome indicated that the DNA-A component has arisen through intermolecular recombination. R. minima plants inoculated with the monomeric clones developed a bright yellow mosaic similar to symptoms observed in naturally infected plants, confirming that the clones were infectious. Nicotiana benthamiana plants biolistically inoculated with monomeric clones developed curling and chlorosis in the newly emerging leaves. RhYMYuV was also detected in symptomatic Desmodium sect. Scorpiurus Benth. (Fabaceae) that were collected near the RhYMYuV-infected plants. © 2010 Springer-Verlag.
• Hernández-Zepeda, C., Brown, J. K., Moreno-Valenzuela, O., Argüello-Astorga, G., Idris, A. M., Carnevali, G., & Rivera-Bustamante, R. (2010). Characterization of Rhynchosia yellow mosaic Yucatan virus, a new recombinant begomovirus associated with two fabaceous weeds in Yucatan, Mexico. Archives of Virology, 155(10), 1571-1579.
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  PMID: 20574644;Abstract: Rhynchosia minima (L.) DC. (Fabaceae) plants exhibiting bright golden mosaic symptoms were previously associated with begomovirus infection in Yucatan, México [1]. To characterize the begomovirus infecting these plants, the complete bipartite genome was cloned and sequenced. Sequence comparisons indicated that the virus was distinct from all other begomoviruses known to date, including those previously identified from symptomatic R. minima, and the name Rhynchosia yellow mosaic Yucatan virus (RhYMYuV) is proposed. Pairwise comparisons indicated that RhYMYuV DNA-A [2,597 nt, (EU021216)] and DNA-B [2,542 nt, (FJ792608)] components shared the highest nt sequence identity with Cabbage leaf curl virus (CaLCuV), 87% for component A and 71% for component B. Phylogenetic analysis indicated that both components of RhYMYuV are most closely related to other New World begomoviruses, having as closest relatives immediate outliers to the major Squash leaf curl virus (SLCV) clade. Recombination analysis of the RhYMYuV genome indicated that the DNA-A component has arisen through intermolecular recombination. R. minima plants inoculated with the monomeric clones developed a bright yellow mosaic similar to symptoms observed in naturally infected plants, confirming that the clones were infectious. Nicotiana benthamiana plants biolistically inoculated with monomeric clones developed curling and chlorosis in the newly emerging leaves. RhYMYuV was also detected in symptomatic Desmodium sect. Scorpiurus Benth. (Fabaceae) that were collected near the RhYMYuV-infected plants. © 2010 Springer-Verlag.
• Idris, A. M., Tuttle, J. R., Robertson, D., Haigler, C. H., & Brown, J. K. (2010). Differential Cotton leaf crumple virus-VIGS-mediated gene silencing and viral genome localization in different Gossypium hirsutum genetic backgrounds. Physiological and Molecular Plant Pathology, 75(1-2), 13-22.
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  Abstract: A Cotton leaf crumple virus (CLCrV)-based gene silencing vector containing a fragment of the Gossypium hirsutum Magnesium chelatase subunit I was used to establish endogenous gene silencing in cotton of varied genetic backgrounds. Biolistic inoculation resulted in systemic and persistent photo-bleaching of the leaves and bolls of the seven cultivars tested, however, the intensity of silencing was variable. CLCrV-VIGS-mediated expression of green fluorescent protein was used to monitor the in planta distribution of the vector, indicating successful phloem invasion in all cultivars tested. Acala SJ-1, one of the cotton cultivars, was identified as a particularly optimal candidate for CLCrV-VIGS-based cotton reverse-genetics. © 2010 Elsevier Ltd.
• Idris, A. M., Tuttle, J. R., Robertson, D., Haigler, C. H., & Brown, J. K. (2010). Differential Cotton leaf crumple virus-VIGS-mediated gene silencing and viral genome localization in different Gossypium hirsutum genetic backgrounds. Physiological and Molecular Plant Pathology, 75(Issue 1-2). doi:10.1016/j.pmpp.2010.07.002
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  A Cotton leaf crumple virus (CLCrV)-based gene silencing vector containing a fragment of the Gossypium hirsutum Magnesium chelatase subunit I was used to establish endogenous gene silencing in cotton of varied genetic backgrounds. Biolistic inoculation resulted in systemic and persistent photo-bleaching of the leaves and bolls of the seven cultivars tested, however, the intensity of silencing was variable. CLCrV-VIGS-mediated expression of green fluorescent protein was used to monitor the in planta distribution of the vector, indicating successful phloem invasion in all cultivars tested. Acala SJ-1, one of the cotton cultivars, was identified as a particularly optimal candidate for CLCrV-VIGS-based cotton reverse-genetics. © 2010 Elsevier Ltd.
• Munyaneza, J. E., Liefting, L. W., Crosslin, J. M., & Brown, J. K. (2010). Potato zebra chip disease: a phytopathological tale.. Plant Health Progress, 11(1), 33. doi:10.1094/php-2010-0317-01-rv
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  Potato zebra chip (ZC) disease is a relative newcomer to the world of important potato diseases. First reported in Mexico in the 1990s, by 2004-2005 the disease was causing serious economic damage in parts of Texas. ZC is now widespread in the south-western and central United States, Mexico, Central America, and was recently reported in New Zealand. By 2006, there seemed to be an association between ZC and the potato psyllid (Bactericera cockerelli). The exact nature of the relationship, however, has only recently been identified by the discovery of a new Candidatus Liberibacter bacterium that is transmitted to potatoes, tomatoes, and other solanaceous hosts by the potato psyllid. This review examines the history of this disease, the association of ZC with the potato psyllid, the host range, and recent research into the bacterial pathogen. Accepted for publication 15 December 2009. Published 17 March 2010.
• Papayiannis, L. C., Hunter, S. C., Iacovides, T., & Brown, J. K. (2010). Detection of Cucurbit yellow stunting disorder virus in cucurbit leaves using sap extracts and real-time TaqMan^® reverse transcription (RT) polymerase chain reaction (PCR). Journal of Phytopathology, 158(7-8), 487-495.
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  Abstract: Cucurbit yellow stunting disorder virus (CYSDV) (genus, Crinivirus: family, Closteroviridae) is an emerging plant pathogen, transmitted by the sweet potato whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), which infects cucurbit crops causing significant economic losses. A TaqMan® real-time fluorescent, one-step reverse transcription (RT), polymerase chain reaction (PCR) assay for the detection of the virus has been developed and optimized. The assay is over 100-fold more sensitive than conventional RT-PCR and involves template preparation that does not require RNA purification. The assay can be accomplished either by first spotting the sap extract on a positively charged nylon membrane and elution, or by the direct addition of crude plant extract into the real-time reaction cocktail. Several factors affecting the efficiency of the tests were studied, such as the type and amount of reverse transcription (RT) enzymes and the use of different additives on the elution extract. The addition of 5 units of RT enzymes in the real-time PCR cocktail and the use of Tween 20, Triton X and Betaine in the virus release buffer resulted in improved detection efficiency. The applicability of the real-time RT-PCR assay was validated with CYSDV isolates from the USA, Mexico, the Mediterranean Basin, Jordan, and the United Arab Emirates and provides a simple, efficient and accurate detection technique, whereas the membrane preparation techniques can be used for long-term storage of samples allowing the shipment of samples from the field to remote laboratories for testing without compromising the reliability of the test. ©, 2009 Blackwell Verlag GmbH.
• Papayiannis, L. C., Hunter, S. C., Iacovides, T., & Brown, J. K. (2010). Detection of Cucurbit yellow stunting disorder virus in cucurbit leaves using sap extracts and real-time TaqMan® reverse transcription (RT) polymerase chain reaction (PCR). Journal of Phytopathology, 158(Issue 7-8). doi:10.1111/j.1439-0434.2009.01647.x
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  Cucurbit yellow stunting disorder virus (CYSDV) (genus, Crinivirus: family, Closteroviridae) is an emerging plant pathogen, transmitted by the sweet potato whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), which infects cucurbit crops causing significant economic losses. A TaqMan® real-time fluorescent, one-step reverse transcription (RT), polymerase chain reaction (PCR) assay for the detection of the virus has been developed and optimized. The assay is over 100-fold more sensitive than conventional RT-PCR and involves template preparation that does not require RNA purification. The assay can be accomplished either by first spotting the sap extract on a positively charged nylon membrane and elution, or by the direct addition of crude plant extract into the real-time reaction cocktail. Several factors affecting the efficiency of the tests were studied, such as the type and amount of reverse transcription (RT) enzymes and the use of different additives on the elution extract. The addition of 5 units of RT enzymes in the real-time PCR cocktail and the use of Tween 20, Triton X and Betaine in the virus release buffer resulted in improved detection efficiency. The applicability of the real-time RT-PCR assay was validated with CYSDV isolates from the USA, Mexico, the Mediterranean Basin, Jordan, and the United Arab Emirates and provides a simple, efficient and accurate detection technique, whereas the membrane preparation techniques can be used for long-term storage of samples allowing the shipment of samples from the field to remote laboratories for testing without compromising the reliability of the test. ©, 2009 Blackwell Verlag GmbH.
• Papayiannis, L. C., Iacovides, T. A., Katis, N. I., & Brown, J. K. (2010). Differentiation of Tomato yellow leaf curl virus and Tomato yellow leaf curl Sardinia virus using real-time TaqMan^® PCR. Journal of Virological Methods, 165(2), 238-245.
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  PMID: 20153376;Abstract: During the past four decades, Tomato yellow leaf curl disease has become one of the major constraints in tomato production worldwide. In the Mediterranean basin, several isolates from two major Begomovirus species are involved in outbreaks and persistent epidemics. A real-time TaqMan® PCR assay was developed and evaluated for the rapid and multiplex detection and differentiation of two begomoviruses often found in mixed infections in the region, Tomato yellow leaf curl virus (TYLCV) and Tomato yellow leaf curl Sardinia virus (TYLCSV). This assay was 1000-fold more sensitive than conventional PCR assays described previously, allowing the use of simple template preparation methods and eliminating the need for total nucleic acid purification. The viral DNA template was obtained by spotting sap extract derived from TYLCV or TYLCSV infected tissues on a nylon membrane or by directly using crude plant extracts in the real-time reaction cocktail. Preliminary results showed that this method can successfully detect and discriminate virus species from infected tomato, bean, pepper and different weed species obtained from the Mediterranean basin, the USA and Japan, allowing the simple, fast and cost-effective testing of a large number of samples in certification schemes. The assay can also be used for the detection of these two begomovirus species in their whitefly vector biotypes of the Bemisia tabaci (Gennadius) species group. © 2010 Elsevier B.V.
• Papayiannis, L. C., Iacovides, T. A., Katis, N. I., & Brown, J. K. (2010). Differentiation of Tomato yellow leaf curl virus and Tomato yellow leaf curl Sardinia virus using real-time TaqMan® PCR. Journal of Virological Methods, 165(Issue 2). doi:10.1016/j.jviromet.2010.02.003
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  During the past four decades, Tomato yellow leaf curl disease has become one of the major constraints in tomato production worldwide. In the Mediterranean basin, several isolates from two major Begomovirus species are involved in outbreaks and persistent epidemics. A real-time TaqMan® PCR assay was developed and evaluated for the rapid and multiplex detection and differentiation of two begomoviruses often found in mixed infections in the region, Tomato yellow leaf curl virus (TYLCV) and Tomato yellow leaf curl Sardinia virus (TYLCSV). This assay was 1000-fold more sensitive than conventional PCR assays described previously, allowing the use of simple template preparation methods and eliminating the need for total nucleic acid purification. The viral DNA template was obtained by spotting sap extract derived from TYLCV or TYLCSV infected tissues on a nylon membrane or by directly using crude plant extracts in the real-time reaction cocktail. Preliminary results showed that this method can successfully detect and discriminate virus species from infected tomato, bean, pepper and different weed species obtained from the Mediterranean basin, the USA and Japan, allowing the simple, fast and cost-effective testing of a large number of samples in certification schemes. The assay can also be used for the detection of these two begomovirus species in their whitefly vector biotypes of the Bemisia tabaci (Gennadius) species group. © 2010 Elsevier B.V.
• Rehman, M., Melgar, J. C., C, J. R., Idris, A. M., & Brown, J. K. (2010). First report of "candidatus liberibacter psyllaurous" or "ca. liberibacter solanacearum" associated with severe foliar chlorosis, curling, and necrosis and tuber discoloration of potato plants in Honduras. Plant Disease, 94(3), 376-.
• Rehman, M., Melgar, J. C., Rivera C, J. M., Idris, A. M., & Brown, J. K. (2010). First report of "candidatus liberibacter psyllaurous" or "ca. liberibacter solanacearum" associated with severe foliar chlorosis, curling, and necrosis and tuber discoloration of potato plants in Honduras. Plant Disease, 94(Issue 3). doi:10.1094/pdis-94-3-0376c
• Brown, J. K., Ling, K. S., Singh, R. P., & Verhoeven, J. T. (2009). First Report of Tomato chlorotic dwarf viroid in Greenhouse Tomatoes in Arizona.. Plant disease, 93(10), 1075. doi:10.1094/pdis-93-10-1075b
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  Tomato chlorotic dwarf viroid (TCDVd), a member of the genus Pospivroid, family Pospiviroidae, was first identified on greenhouse tomato (Solanum lycopersicum) in Canada (2). Since then, it has also been reported elsewhere, e.g., on tomato in Colorado (4). During 2006 in Arizona, tomato plants in a large greenhouse facility with continuous tomato production exhibited viroid-like symptoms of plant stunting and chlorosis of the young leaves. Symptomatic plants were often located along the edge of the row, indicating the presence of a mechanical transmissible agent. Approximately 4% of the plants in this greenhouse were symptomatic in 2008. Symptoms were distinctly different from those caused by Pepino mosaic virus (PepMV), a virus that was generally present in this greenhouse and also in our test samples. Other commonly occurring tomato viruses were ruled out by serological, PCR, or reverse transcription (RT)-PCR tests in multiple laboratories. RT-PCR with two sets of universal pospiviroid primers, PospiI-FW/RE and Vid-FW/RE (4), yielded amplicons of the expected sizes of 196 and 360 bp in three samples collected from symptomatic plants. Direct sequencing of the amplicons revealed that the genome was 360 nt and 100% identical to the type TCDVd from Canada (GenBank Accession No. AF162131) (2). Mechanical inoculation with leaf tissue extract from four samples to plants of the tomato 'Money-Maker' resulted in the same viroid-like symptoms and TCDVd was confirmed in these plants by RT-PCR and sequencing. In both 2007 and 2008, 18 samples were tested using primers PSTVd-F and PSTVd-R (1), which are capable of amplifying the full TCDVd genome. Analysis of the sequences from the amplicons revealed two genotypes of TCDVd. The first genotype (GenBank Accession No. FJ822877) was identical to the type TCDVd and found in 11 samples from 2007 and one from 2008. The second genotype (GenBank Accession No. FJ822878) was 361 nt, differing from the first by nine nucleotide substitutions, 2 insertions, and 1 deletion. This second genotype was found in 7 and 17 samples from 2007 and 2008, respectively, and showed the highest sequence identity (97%) to a Japanese tomato isolate (AB329668) and a much lower sequence identity (92%) to a U.S. isolate previously identified in Colorado (AY372399) (4). The origin of TCDVd in this outbreak is not clear. The genotype identified first could have been introduced from a neighboring greenhouse where the disease was observed before 2006 and where this genotype also was identified in 2007. The second genotype may have been introduced from infected seed since TCDVd has recently been shown to be seed transmitted in tomato (3). To our knowledge, this is the first report of natural occurrence of TCDVd in Arizona. References: (1) A. M. Shamloul et al. Can. J. Plant Pathol. 19:89, 1997. (2) R. P. Singh et al. J. Gen. Virol. 80:2823, 1999. (3) R. P. Singh and A. D. Dilworth. Eur. J. Plant Pathol. 123:111, 2009. (4) J. Th. J. Verhoeven et al. Eur. J. Plant Pathol. 110:823, 2004.
• Cicero, J. M., Brown, J. K., Roberts, P. D., & Stansly, P. A. (2009). The digestive system of Diaphorina citri and Bactericera cockerelli (Hemiptera: Psyllidae). Annals of the Entomological Society of America, 102(4), 650-665.
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  Abstract: The psyllids Diaphorina citri (Kuwayama) and Bactericera cockerelli (Sulc) (Hemiptera: Psyllidae) are vectors of Candidatus Liberibacter spp., bacterial agents of serious agricultural diseases. The rapidly expanding geographical distributions of these diseases dictate increasing urgency for their control. Therefore, it is important to gain a full understanding of the psyllid digestive system in which the vector-pathogen interactions begin. Their midgut is looped so that the foregut-midgut and midguthindgut transitional regions are grafted together to form a composite tube within a filter chamber sheath. Unwanted sap components could thus be extracted directly into the hindgut, bypassing digestion. The esophageal lumen enters the chamber axially to become the inner midgut lumen. The upper half of this midgut section is bulbous while the lower half is tubular. The tube lumen exits the chamber to become the external midgut lumen, which loops through the hemocoel and reenters the chamber, becoming the inner hindgut lumen. The inner hindgut tracks the adherent inner midgut in an antiparallel direction. The composite tube is helically wound and undergoes one hairpin turn. The inner hindgut straps diagonally across the bulb and then exits the chamber next to the esophagus as the outer hindgut to anus. The source of honeydew, whether filtrate, midgut waste, or both, is questioned. Paired, spherical, primary salivary glands each have a digitate accessory gland and a lateral duct that leads to the stylets. The accessory gland lumen is lined exclusively with intima, whereas the primary gland apical cell membranes are indicated to be more complex. © 2009 Entomological Society of America.
• Cicero, J. M., Brown, J. K., Roberts, P. D., & Stansly, P. A. (2009). The digestive system of Diaphorina citri and Bactericera cockerelli (Hemiptera: Psyllidae). Annals of the Entomological Society of America, 102(Issue 4). doi:10.1603/008.102.0410
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  The psyllids Diaphorina citri (Kuwayama) and Bactericera cockerelli (Sulc) (Hemiptera: Psyllidae) are vectors of Candidatus Liberibacter spp., bacterial agents of serious agricultural diseases. The rapidly expanding geographical distributions of these diseases dictate increasing urgency for their control. Therefore, it is important to gain a full understanding of the psyllid digestive system in which the vector-pathogen interactions begin. Their midgut is looped so that the foregut-midgut and midguthindgut transitional regions are grafted together to form a composite tube within a filter chamber sheath. Unwanted sap components could thus be extracted directly into the hindgut, bypassing digestion. The esophageal lumen enters the chamber axially to become the inner midgut lumen. The upper half of this midgut section is bulbous while the lower half is tubular. The tube lumen exits the chamber to become the external midgut lumen, which loops through the hemocoel and reenters the chamber, becoming the inner hindgut lumen. The inner hindgut tracks the adherent inner midgut in an antiparallel direction. The composite tube is helically wound and undergoes one hairpin turn. The inner hindgut straps diagonally across the bulb and then exits the chamber next to the esophagus as the outer hindgut to anus. The source of honeydew, whether filtrate, midgut waste, or both, is questioned. Paired, spherical, primary salivary glands each have a digitate accessory gland and a lateral duct that leads to the stylets. The accessory gland lumen is lined exclusively with intima, whereas the primary gland apical cell membranes are indicated to be more complex. © 2009 Entomological Society of America.
• Collins, A. M., Brown, J. K., Rehman, M. M., & Roye, M. E. (2009). Complete nucleotide sequence of an isolate of Euphorbia mosaic virus that infects Euphorbia heterophylla and Wissadula amplissima in Jamaica. Archives of Virology, 154(11), 1859-1860.
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  PMID: 19774336;PMCID: PMC2853933;
• Collins, A. M., Brown, J. K., Rehman, M. M., & Roye, M. E. (2009). Complete nucleotide sequence of an isolate of Euphorbia mosaic virus that infects Euphorbia heterophylla and Wissadula amplissima in Jamaica. Archives of Virology, 154(Issue 11). doi:10.1007/s00705-009-0508-4
• Collins, A. M., Mujaddad-Ur-Rehman, M., Brown, J. K., Reddy, C., Wang, A., Fondong, V., & Roye, M. E. (2009). Molecular characterization and experimental host range of an isolate of Wissadula golden mosaic St. Thomas virus. Virus Genes, 39(3), 387-395.
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  PMID: 19768650;Abstract: Partial genome segments of a begomovirus were previously amplified from Wissadula amplissima exhibiting yellow-mosaic and leaf-curl symptoms in the parish of St. Thomas, Jamaica and this isolate assigned to a tentative begomovirus species, Wissadula golden mosaic St. Thomas virus. To clone the complete genome of this isolate of Wissadula golden mosaic St. Thomas virus, abutting primers were designed to PCR amplify its full-length DNA-A and DNA-B components. Sequence analysis of the complete begomovirus genome obtained, confirmed that it belongs to a distinct begomovirus species and this isolate was named Wissadula golden mosaic St. Thomas virus-[Jamaica:Albion:2005] (WGMSTV-[JM:Alb:05]). The genome of WGMSTV-[JM:Alb:05] is organized similar to that of other bipartite Western Hemisphere begomoviruses. Phylogenetic analyses placed the genome components of WGMSTV-[JM:Alb:05] in the Abutilon mosaic virus clade and showed that the DNA-A component is most closely related to four begomovirus species from Cuba, Tobacco leaf curl Cuba virus, Tobacco leaf rugose virus, Tobacco mottle leaf curl virus, and Tomato yellow distortion leaf virus. The putative Rep-binding-site motif in the common region of WGMSTV-[JM:Alb:05] was observed to be identical to that of Chino del tomate virus-Tomato [Mexico:Sinaloa:1983], Sida yellow mosaic Yucatan virus-[Mexico:Yucatan:2005], and Tomato leaf curl Sinaloa virus-[Nicaragua:Santa Lucia], suggesting that WGMSTV-[JM:Alb:05] is capable of forming viable pseudo-recombinants with these begomoviruses, but not with other members of the Abutilon mosaic virus clade. Biolistic inoculation of test plant species with partial dimers of the WGMSTV-[JM:Alb:05] DNA-A and DNA-B components showed that the virus was infectious to Nicotiana benthamiana and W. amplissima and the cultivated species Phaseolus vulgaris (kidney bean) and Lycopersicon esculentum (tomato). Infected W. amplissima plants developed symptoms similar to symptoms observed under field conditions, confirming that this virus is a causal agent of Wissadula yellow mosaic disease in W. amplissima. © 2009 Springer Science+Business Media, LLC.
• Collins, A. M., Mujaddad-Ur-Rehman, M., Brown, J. K., Reddy, C., Wang, A., Fondong, V., & Roye, M. E. (2009). Molecular characterization and experimental host range of an isolate of Wissadula golden mosaic St. Thomas virus. Virus Genes, 39(Issue 3). doi:10.1007/s11262-009-0401-y
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  Partial genome segments of a begomovirus were previously amplified from Wissadula amplissima exhibiting yellow-mosaic and leaf-curl symptoms in the parish of St. Thomas, Jamaica and this isolate assigned to a tentative begomovirus species, Wissadula golden mosaic St. Thomas virus. To clone the complete genome of this isolate of Wissadula golden mosaic St. Thomas virus, abutting primers were designed to PCR amplify its full-length DNA-A and DNA-B components. Sequence analysis of the complete begomovirus genome obtained, confirmed that it belongs to a distinct begomovirus species and this isolate was named Wissadula golden mosaic St. Thomas virus-[Jamaica:Albion:2005] (WGMSTV-[JM:Alb:05]). The genome of WGMSTV-[JM:Alb:05] is organized similar to that of other bipartite Western Hemisphere begomoviruses. Phylogenetic analyses placed the genome components of WGMSTV-[JM:Alb:05] in the Abutilon mosaic virus clade and showed that the DNA-A component is most closely related to four begomovirus species from Cuba, Tobacco leaf curl Cuba virus, Tobacco leaf rugose virus, Tobacco mottle leaf curl virus, and Tomato yellow distortion leaf virus. The putative Rep-binding-site motif in the common region of WGMSTV-[JM:Alb:05] was observed to be identical to that of Chino del tomate virus-Tomato [Mexico:Sinaloa:1983], Sida yellow mosaic Yucatan virus-[Mexico:Yucatan:2005], and Tomato leaf curl Sinaloa virus-[Nicaragua:Santa Lucia], suggesting that WGMSTV-[JM:Alb:05] is capable of forming viable pseudo-recombinants with these begomoviruses, but not with other members of the Abutilon mosaic virus clade. Biolistic inoculation of test plant species with partial dimers of the WGMSTV-[JM:Alb:05] DNA-A and DNA-B components showed that the virus was infectious to Nicotiana benthamiana and W. amplissima and the cultivated species Phaseolus vulgaris (kidney bean) and Lycopersicon esculentum (tomato). Infected W. amplissima plants developed symptoms similar to symptoms observed under field conditions, confirming that this virus is a causal agent of Wissadula yellow mosaic disease in W. amplissima. © 2009 Springer Science+Business Media, LLC.
• Hernández-Zepeda, C., Argüello-Astorga, G., Idris, A. M., Carnevali, G., Brown, J. K., & Moreno-Valenzuela, O. A. (2009). Molecular characterization and phylogenetic relationships of Desmodium leaf distortion virus (DeLDV): A new begomovirus infecting Desmodium glabrum in Yucatan, Mexico. Virus Genes, 39(3), 371-374.
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  PMID: 19757008;Abstract: The complete DNA-A component sequence of Desmodium leaf distortion virus (DeLDV, Begomovirus) isolated in Yucatan was determined to be 2569 nucleotides (nt) in length, and it was most closely related to Cotton leaf crumple virus-California (CLCrV-[Cal]), at 76%. The complete DNA-B component sequence was 2514 nt in length, and shared its highest nucleotide identity (60%) with Potato yellow mosaic Trinidad virus (PYMTV). Phylogenetic analyses group the DeLDV DNA-A component in the SLCV clade, whereas, the DeLDV DNA-B was grouped with the Abutilon mosaic virus clade, which also contains PYMV, suggesting that the DeLDV components have distinct evolutionary histories, possibly as the result of recombination and reassortment. © 2009 Springer Science+Business Media, LLC.
• Hernández-Zepeda, C., Argüello-Astorga, G., Idris, A. M., Carnevali, G., Brown, J. K., & Moreno-Valenzuela, O. A. (2009). Molecular characterization and phylogenetic relationships of Desmodium leaf distortion virus (DeLDV): A new begomovirus infecting Desmodium glabrum in Yucatan, Mexico. Virus Genes, 39(Issue 3). doi:10.1007/s11262-009-0398-2
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  The complete DNA-A component sequence of Desmodium leaf distortion virus (DeLDV, Begomovirus) isolated in Yucatan was determined to be 2569 nucleotides (nt) in length, and it was most closely related to Cotton leaf crumple virus-California (CLCrV-[Cal]), at 76%. The complete DNA-B component sequence was 2514 nt in length, and shared its highest nucleotide identity (60%) with Potato yellow mosaic Trinidad virus (PYMTV). Phylogenetic analyses group the DeLDV DNA-A component in the SLCV clade, whereas, the DeLDV DNA-B was grouped with the Abutilon mosaic virus clade, which also contains PYMV, suggesting that the DeLDV components have distinct evolutionary histories, possibly as the result of recombination and reassortment. © 2009 Springer Science+Business Media, LLC.
• Leke, W. N., Njualem, D. K., Nchinda, V. P., Ngoko, Z., Zok, S., Ngeve, J. M., Brown, J. K., & Kvarnheden, A. (2009). Molecular identification of Maize streak virus reveals the first evidence for a subtype A1 isolate infecting maize in Cameroon. Plant Pathology, 58(4), 782-.
• Leke, W. N., Njualem, D. K., Nchinda, V. P., Ngoko, Z., Zok, S., Ngeve, J. M., Brown, J. K., & Kvarnheden, A. (2009). Molecular identification of Maize streak virus reveals the first evidence for a subtype A1 isolate infecting maize in Cameroon. Plant Pathology, 58(Issue 4). doi:10.1111/j.1365-3059.2009.02133.x
• Papayiannis, L. C., Brown, J. K., Seraphides, N. A., Hadjistylli, M., Ioannou, N., & Katis, N. I. (2009). A real-time PCR assay to differentiate the B and Q biotypes of the Bemisia tabaci complex in Cyprus. Bulletin of Entomological Research, 99(6), 573-582.
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  PMID: 19203404;Abstract: A real-time PCR assay based on TaqMan® technology was developed and evaluated for the rapid detection of the B and Q biotypes of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). A survey was conducted during 2005-2007 in order to identify the distribution and prevalence of B. tabaci biotypes in Cyprus using the real-time PCR assay. More than 700 adult whiteflies collected from 35 cultivated and weed plant species were individually haplotyped using TaqMan® PCR, and the results of the assay were validated by restriction fragment length polymorphism analysis and DNA sequencing of the mitochondrial cytochrome oxidase I (mtCOI) gene. Two biotypes, B and Q, were identified in the collected plant species on the island. The real-time PCR and RFLP assay consistently yielded the same results, although the real-time assay was more sensitive and less time consuming. Phylogenetic analysis of the mtCOI DNA sequences corroborated the identity of the B and Q biotypes 100% of the time and by phylogenetic analysis the haplotypes grouped, as expected, in the major North African-Mediterranean-Middle Eastern clade of the B. tabaci complex. © 2009 Cambridge University Press.
• Papayiannis, L. C., Brown, J. K., Seraphides, N. A., Hadjistylli, M., Ioannou, N., & Katis, N. I. (2009). A real-time PCR assay to differentiate the B and Q biotypes of the Bemisia tabaci complex in Cyprus. Bulletin of Entomological Research, 99(Issue 6). doi:10.1017/s0007485308006603
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  A real-time PCR assay based on TaqMan® technology was developed and evaluated for the rapid detection of the B and Q biotypes of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). A survey was conducted during 2005-2007 in order to identify the distribution and prevalence of B. tabaci biotypes in Cyprus using the real-time PCR assay. More than 700 adult whiteflies collected from 35 cultivated and weed plant species were individually haplotyped using TaqMan® PCR, and the results of the assay were validated by restriction fragment length polymorphism analysis and DNA sequencing of the mitochondrial cytochrome oxidase I (mtCOI) gene. Two biotypes, B and Q, were identified in the collected plant species on the island. The real-time PCR and RFLP assay consistently yielded the same results, although the real-time assay was more sensitive and less time consuming. Phylogenetic analysis of the mtCOI DNA sequences corroborated the identity of the B and Q biotypes 100% of the time and by phylogenetic analysis the haplotypes grouped, as expected, in the major North African-Mediterranean-Middle Eastern clade of the B. tabaci complex. © 2009 Cambridge University Press.
• Sabanadzovic, S., Valverde, R. A., Brown, J. K., Martin, R. R., & Tzanetakis, I. E. (2009). Southern tomato virus: The link between the families Totiviridae and Partitiviridae. Virus Research, 140(1-2), 130-137.
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  PMID: 19118586;Abstract: A dsRNA virus with a genome of 3.5 kb was isolated from field and greenhouse-grown tomato plants of different cultivars and geographic locations in North America. Cloning and sequencing of the viral genome showed the presence of two partially overlapping open reading frames (ORFs), and a genomic organization resembling members of the family Totiviridae that comprises fungal and protozoan viruses, but not plant viruses. The 5′-proximal ORF codes for a 377 amino acid-long protein of unknown function, whereas the product of ORF2 contains typical motifs of an RNA-dependant RNA-polymerase and is likely expressed by a +1 ribosomal frame shift. Despite the similarity in the genome organization with members of the family Totiviridae, this virus shared very limited sequence homology with known totiviruses or with other viruses. Repeated attempts to detect the presence of an endophytic fungus as the possible host of the virus failed, supporting its phytoviral nature. The virus was efficiently transmitted by seed but not mechanically and/or by grafting. Phylogenetic analyses revealed that this virus, for which the name Southern tomato virus (STV) is proposed, belongs to a partitivirus-like lineage and represents a species of a new taxon of plant viruses. © 2008 Elsevier B.V.
• Sabanadzovic, S., Valverde, R. A., Brown, J. K., Martin, R. R., & Tzanetakis, I. E. (2009). Southern tomato virus: The link between the families Totiviridae and Partitiviridae. Virus Research, 140(Issue 1-2). doi:10.1016/j.virusres.2008.11.018
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  A dsRNA virus with a genome of 3.5 kb was isolated from field and greenhouse-grown tomato plants of different cultivars and geographic locations in North America. Cloning and sequencing of the viral genome showed the presence of two partially overlapping open reading frames (ORFs), and a genomic organization resembling members of the family Totiviridae that comprises fungal and protozoan viruses, but not plant viruses. The 5′-proximal ORF codes for a 377 amino acid-long protein of unknown function, whereas the product of ORF2 contains typical motifs of an RNA-dependant RNA-polymerase and is likely expressed by a +1 ribosomal frame shift. Despite the similarity in the genome organization with members of the family Totiviridae, this virus shared very limited sequence homology with known totiviruses or with other viruses. Repeated attempts to detect the presence of an endophytic fungus as the possible host of the virus failed, supporting its phytoviral nature. The virus was efficiently transmitted by seed but not mechanically and/or by grafting. Phylogenetic analyses revealed that this virus, for which the name Southern tomato virus (STV) is proposed, belongs to a partitivirus-like lineage and represents a species of a new taxon of plant viruses. © 2008 Elsevier B.V.
• Briddon, R. W., Brown, J. K., Moriones, E., Stanley, J., Zerbini, M., Zhou, X., & Fauquet, C. M. (2008). Recommendations for the classification and nomenclature of the DNA-β satellites of begomoviruses. Archives of Virology, 153(4), 763-781.
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  PMID: 18247103;Abstract: The symptom-modulating, single-stranded DNA satellites (known as DNA-β) associated with begomoviruses (family Geminiviridae) have proven to be widespread and important components of a large number of plant diseases across the Old World. Since they were first identified in 2000, over 260 full-length sequences (∼1,360 nucleotides) have been deposited with databases, and this number increases daily. This has highlighted the need for a standardised, concise and unambiguous nomenclature for these components, as well as a meaningful and robust classification system. Pairwise comparisons of all available full-length DNA-β sequences indicate that the minimum numbers of pairs occur at a sequence identity of 78%, which we propose as the species demarcation threshold for a distinct DNA-β. This threshold value divides the presently known DNA-β sequences into 51 distinct satellite species. In addition, we propose a naming convention for the satellites that is based upon the system already in use for geminiviruses. This maintains, whenever possible, the association with the helper begomovirus, the disease symptoms and the host plant and provides a logical and consistent system for referring to already recognised and newly identified satellites. © 2008 Springer-Verlag.
• Briddon, R. W., Brown, J. K., Moriones, E., Stanley, J., Zerbini, M., Zhou, X., & Fauquet, C. M. (2008). Recommendations for the classification and nomenclature of the DNA-β satellites of begomoviruses. Archives of Virology, 153(Issue 4). doi:10.1007/s00705-007-0013-6
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  The symptom-modulating, single-stranded DNA satellites (known as DNA-β) associated with begomoviruses (family Geminiviridae) have proven to be widespread and important components of a large number of plant diseases across the Old World. Since they were first identified in 2000, over 260 full-length sequences (∼1,360 nucleotides) have been deposited with databases, and this number increases daily. This has highlighted the need for a standardised, concise and unambiguous nomenclature for these components, as well as a meaningful and robust classification system. Pairwise comparisons of all available full-length DNA-β sequences indicate that the minimum numbers of pairs occur at a sequence identity of 78%, which we propose as the species demarcation threshold for a distinct DNA-β. This threshold value divides the presently known DNA-β sequences into 51 distinct satellite species. In addition, we propose a naming convention for the satellites that is based upon the system already in use for geminiviruses. This maintains, whenever possible, the association with the helper begomovirus, the disease symptoms and the host plant and provides a logical and consistent system for referring to already recognised and newly identified satellites. © 2008 Springer-Verlag.
• Brown, J. K., Burke, J. I., Havis, N. D., Makepeace, J. C., & Oxley, S. J. (2008). A method of inoculating barley seedlings with Ramularia collo‐cygni. Plant Pathology, 57(6), 991-999. doi:10.1111/j.1365-3059.2008.01892.x
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  A method of inoculating seedlings with the fungus Ramularia collo-cygni, the causal agent of ramularia leaf spot (RLS), an increasingly important problem in barley in Europe and elsewhere, is described. Symptoms of RLS similar to those found in the field were reproduced on seedlings and the fungus was re-isolated from them, fulfilling the third and fourth of Koch's postulates. The method was similar to one used for the related fungus, Mycosphaerella graminicola (anamorph Septoria tritici), a pathogen of wheat. Briefly, plants were sprayed with a suspension of R. collo-cygni mycelium fragments, incubated at 15°C, first in darkness for 48 h then in a 16-h-light/8-h-dark cycle. Disease levels reached saturation when plants were sprayed to runoff with a suspension of 480 cm2 of mycelium, scraped from the entire surface of 7·5 Petri dishes (9 cm diameter) and sieved, in 50 mL water. Growth of seedlings in high light intensity (900 µmol m−2 s−1, 16-h daylength) before inoculation increased disease symptoms, but reduced disease when applied after inoculation. In contrast to M. graminicola, near-ultraviolet light after inoculation reduced symptom development. It is proposed that for the full development of RLS, plants should be grown in a stressful environment before inoculation. Nine barley lines were assessed for their resistance to RLS as seedlings and a subset were tested in field trials with natural infection by R. collo-cygni. There was cultivar-by-isolate interaction in the amount of RLS symptoms on seedlings. RLS levels on adult plants in field plots were correlated with RLS scores on seedlings formed by one isolate but not the other.
• Fauquet, C. M., Briddon, R. W., Brown, J. K., Moriones, E., Stanley, J., Zerbini, M., & Zhou, X. (2008). Geminivirus strain demarcation and nomenclature. Archives of Virology, 153(4), 783-821.
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  PMID: 18256781;Abstract: Geminivirus taxonomy and nomenclature is growing in complexity with the number of genomic sequences deposited in sequence databases. Taxonomic and nomenclatural updates are published at regular intervals (Fauquet et al. in Arch Virol 145:1743-1761, 2000, Arch Virol 148:405-421, 2003). A system to standardize virus names, and corresponding guidelines, has been proposed (Fauquet et al. in Arch Virol 145:1743-1761, 2000). This system is now followed by a large number of geminivirologists in the world, making geminivirus nomenclature more transparent and useful. In 2003, due to difficulties inherent in species identification, the ICTV Geminiviridae Study Group proposed new species demarcation criteria, the most important of which being an 89% nucleotide (nt) identity threshold between full-length DNA-A component nucleotide sequences for begomovirus species. This threshold has been utilised since with general satisfaction. More recently, an article has been published to clarify the terminology used to describe virus entities below the species level [5]. The present publication is proposing demarcation criteria and guidelines to classify and name geminiviruses below the species level. Using the Clustal V algorithm (DNAStar MegAlign software), the distribution of pairwise sequence comparisons, for pairs of sequences below the species taxonomic level, identified two peaks: one at 85-94% nt identity that is proposed to correspond to "strain" comparisons and one at 92-100% identity that corresponds to "variant" comparisons. Guidelines for descriptors for each of these levels are proposed to standardize nomenclature under the species level. In this publication we review the status of geminivirus species and strain demarcation as well as providing updated isolate descriptors for a total of 672 begomovirus isolates. As a consequence, we have revised the status of some virus isolates to classify them as "strains", whereas several others previously classified as "strains" have been upgraded to "species". In all other respects, the classification system has remained robust, and we therefore propose to continue using it. An updated list of all geminivirus isolates and a phylogenetic tree with one representative isolate per species are provided. © 2008 Springer-Verlag.
• Fauquet, C. M., Briddon, R. W., Brown, J. K., Moriones, E., Stanley, J., Zerbini, M., & Zhou, X. (2008). Geminivirus strain demarcation and nomenclature. Archives of Virology, 153(Issue 4). doi:10.1007/s00705-008-0037-6
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  Geminivirus taxonomy and nomenclature is growing in complexity with the number of genomic sequences deposited in sequence databases. Taxonomic and nomenclatural updates are published at regular intervals (Fauquet et al. in Arch Virol 145:1743-1761, 2000, Arch Virol 148:405-421, 2003). A system to standardize virus names, and corresponding guidelines, has been proposed (Fauquet et al. in Arch Virol 145:1743-1761, 2000). This system is now followed by a large number of geminivirologists in the world, making geminivirus nomenclature more transparent and useful. In 2003, due to difficulties inherent in species identification, the ICTV Geminiviridae Study Group proposed new species demarcation criteria, the most important of which being an 89% nucleotide (nt) identity threshold between full-length DNA-A component nucleotide sequences for begomovirus species. This threshold has been utilised since with general satisfaction. More recently, an article has been published to clarify the terminology used to describe virus entities below the species level [5]. The present publication is proposing demarcation criteria and guidelines to classify and name geminiviruses below the species level. Using the Clustal V algorithm (DNAStar MegAlign software), the distribution of pairwise sequence comparisons, for pairs of sequences below the species taxonomic level, identified two peaks: one at 85-94% nt identity that is proposed to correspond to "strain" comparisons and one at 92-100% identity that corresponds to "variant" comparisons. Guidelines for descriptors for each of these levels are proposed to standardize nomenclature under the species level. In this publication we review the status of geminivirus species and strain demarcation as well as providing updated isolate descriptors for a total of 672 begomovirus isolates. As a consequence, we have revised the status of some virus isolates to classify them as "strains", whereas several others previously classified as "strains" have been upgraded to "species". In all other respects, the classification system has remained robust, and we therefore propose to continue using it. An updated list of all geminivirus isolates and a phylogenetic tree with one representative isolate per species are provided. © 2008 Springer-Verlag.
• Idris, A. M., Mills-Lujan, K., Martin, K., & Brown, J. K. (2008). Melon chlorotic leaf curl virus: Characterization and differential reassortment with closest relatives reveal adaptive virulence in the squash leaf curl virus clade and host shifting by the host-restricted bean calico mosaic virus. Journal of Virology, 82(4), 1959-1967.
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  PMID: 18057231;PMCID: PMC2258725;Abstract: The genome components of the Melon chlorotic leaf curl virus (MCLCuV) were cloned from symptomatic cantaloupe leaves collected in Guatemala during 2002. The MCLCuV DNA-A and DNA-B components shared their closest nucleotide identities among begomoviruses, at ∼90 and 81%, respectively, with a papaya isolate of MCLCuV from Costa Rica. The closest relatives at the species level were other members of the Squash leaf curl virus (SLCV) clade, which is endemic in the southwestern United States and Mexico. Biolistic inoculation of cantaloupe seedlings with the MCLCuV DNA-A and -B components resulted in the development of characteristic disease symptoms, providing definitive evidence of causality. MCLCuV experimentally infected species within the Cucurbitaceae, Fabaceae, and Solanaceae. The potential for interspecific reassortment was examined for MCLCuV and its closest relatives, including the bean-restricted Bean calico mosaic virus (BCaMV), and three other cucurbit-infecting species, Cucurbit leaf crumple virus (CuLCrV), SLCV, and SMLCV. The cucurbit viruses have distinct but overlapping host ranges. All possible reassortants were established using heterologous combinations of the DNA-A or DNA-B components. Surprisingly, only certain reassortants arising from MCLCuV and BCaMV, or MCLCuV and CuLCrV, were viable in bean, even though it is a host of all of the "wild-type" (parent) viruses. The bean-restricted BCaMV was differentially assisted in systemically infecting the cucurbit test species by the components of the four cucurbit-adapted begomoviruses. In certain heterologous combinations, the BCaMV DNA-A or -B component was able to infect one or more cucurbit species. Generally, the reassortants were less virulent in the test hosts than the respective wild-type (parent) viruses, strongly implicating adaptive modulation of virulence. This is the first illustration of reassortment resulting in the host range expansion of a host-restricted begomovirus. Copyright © 2008, American Society for Microbiology. All Rights Reserved.
• Idris, A. M., Mills-Lujan, K., Martin, K., & Brown, J. K. (2008). Melon chlorotic leaf curl virus: Characterization and differential reassortment with closest relatives reveal adaptive virulence in the squash leaf curl virus clade and host shifting by the host-restricted bean calico mosaic virus. Journal of Virology, 82(Issue 4). doi:10.1128/jvi.01992-07
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  The genome components of the Melon chlorotic leaf curl virus (MCLCuV) were cloned from symptomatic cantaloupe leaves collected in Guatemala during 2002. The MCLCuV DNA-A and DNA-B components shared their closest nucleotide identities among begomoviruses, at ∼90 and 81%, respectively, with a papaya isolate of MCLCuV from Costa Rica. The closest relatives at the species level were other members of the Squash leaf curl virus (SLCV) clade, which is endemic in the southwestern United States and Mexico. Biolistic inoculation of cantaloupe seedlings with the MCLCuV DNA-A and -B components resulted in the development of characteristic disease symptoms, providing definitive evidence of causality. MCLCuV experimentally infected species within the Cucurbitaceae, Fabaceae, and Solanaceae. The potential for interspecific reassortment was examined for MCLCuV and its closest relatives, including the bean-restricted Bean calico mosaic virus (BCaMV), and three other cucurbit-infecting species, Cucurbit leaf crumple virus (CuLCrV), SLCV, and SMLCV. The cucurbit viruses have distinct but overlapping host ranges. All possible reassortants were established using heterologous combinations of the DNA-A or DNA-B components. Surprisingly, only certain reassortants arising from MCLCuV and BCaMV, or MCLCuV and CuLCrV, were viable in bean, even though it is a host of all of the "wild-type" (parent) viruses. The bean-restricted BCaMV was differentially assisted in systemically infecting the cucurbit test species by the components of the four cucurbit-adapted begomoviruses. In certain heterologous combinations, the BCaMV DNA-A or -B component was able to infect one or more cucurbit species. Generally, the reassortants were less virulent in the test hosts than the respective wild-type (parent) viruses, strongly implicating adaptive modulation of virulence. This is the first illustration of reassortment resulting in the host range expansion of a host-restricted begomovirus. Copyright © 2008, American Society for Microbiology. All Rights Reserved.
• Khan, A. J., Idris, A. M., Al-Saady, N. A., Al-Mahruki, M. S., Al-Subhi, A. M., & Brown, J. K. (2008). A divergent isolate of Tomato yellow leaf curl virus from Oman with an associated DNAβ satellite: An evolutionary link between Asian and the Middle Eastern virus-satellite complexes. Virus Genes, 36(1), 169-176.
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  PMID: 17932737;Abstract: Tomato is cultivated in the coastal region of Al-Batinah, in the Sultanate of Oman, during the winter season, to meet the high demand for fresh produce in the domestic market. In order to identify the causal agent of a widespread disease associated with infestations of the whitefly Bemisia tabaci (Genn.) leaves were collected from tomato plants showing symptoms characteristic of the disease in Al-Batinah during 2004 and 2005. Total nucleic acids were isolated from the tomato leaves and used as the template for Φ29 DNA polymerase amplification of begomoviral circular DNA. Putative full unit length begomoviral DNA multimers were digested with Nco I and cloned into the plasmid vector pGEM7Zf+. The complete nucleotide (nt) sequence was determined as 2,765 bases, indicative of a monopartite begomoviral genome. A comparison of the genome sequence for the seven field isolates examined, indicated that they shared 99% nt identity. The virus from Oman was most closely related to TYLCV-IR at 91% nt identity, a monopartite begomoviral species described previously from Iran. Based on the guidelines of the ICTV the Oman isolate has been designated TYLCV-Om and is considered an isolate of TYLCV-IR. A satellite DNA (satDNA β), was amplified by polymerase chain reaction using degenerate primers and cloned, and the DNA sequence was determined. Analysis of the complete nt sequence of 1,371 bases indicated that the satDNA shared 88.5% similarity with its closest relatives, which are DNAβ molecules from tomato in Pakistan. This is the first report of a satDNA β associated with the TYLCV species. The TYLCV-Om and associated satDNA, thus represent a begomovirus-complex at the Asian-Middle East crossroads that quiet uniquely share geographical and genetic hallmarks of both. © 2007 Springer Science+Business Media, LLC.
• Khan, A. J., Idris, A. M., Al-Saady, N. A., Al-Mahruki, M. S., Al-Subhi, A. M., & Brown, J. K. (2008). A divergent isolate of Tomato yellow leaf curl virus from Oman with an associated DNAβ satellite: An evolutionary link between Asian and the Middle Eastern virus-satellite complexes. Virus Genes, 36(Issue 1). doi:10.1007/s11262-007-0163-3
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  Tomato is cultivated in the coastal region of Al-Batinah, in the Sultanate of Oman, during the winter season, to meet the high demand for fresh produce in the domestic market. In order to identify the causal agent of a widespread disease associated with infestations of the whitefly Bemisia tabaci (Genn.) leaves were collected from tomato plants showing symptoms characteristic of the disease in Al-Batinah during 2004 and 2005. Total nucleic acids were isolated from the tomato leaves and used as the template for Φ29 DNA polymerase amplification of begomoviral circular DNA. Putative full unit length begomoviral DNA multimers were digested with Nco I and cloned into the plasmid vector pGEM7Zf+. The complete nucleotide (nt) sequence was determined as 2,765 bases, indicative of a monopartite begomoviral genome. A comparison of the genome sequence for the seven field isolates examined, indicated that they shared 99% nt identity. The virus from Oman was most closely related to TYLCV-IR at 91% nt identity, a monopartite begomoviral species described previously from Iran. Based on the guidelines of the ICTV the Oman isolate has been designated TYLCV-Om and is considered an isolate of TYLCV-IR. A satellite DNA (satDNA β), was amplified by polymerase chain reaction using degenerate primers and cloned, and the DNA sequence was determined. Analysis of the complete nt sequence of 1,371 bases indicated that the satDNA shared 88.5% similarity with its closest relatives, which are DNAβ molecules from tomato in Pakistan. This is the first report of a satDNA β associated with the TYLCV species. The TYLCV-Om and associated satDNA, thus represent a begomovirus-complex at the Asian-Middle East crossroads that quiet uniquely share geographical and genetic hallmarks of both. © 2007 Springer Science+Business Media, LLC.
• Nunes, E. S., Brown, J. K., Moreira, A. G., Watson, G., Lourenção, A. L., Piedade, S. M., A., J., & Vieira, M. L. (2008). First report and differential colonization of Passiflora species by the B biotype of Bemisia tabaci (Gennadius) (hemiptera: Aleyrodidae) in Brazil. Neotropical Entomology, 37(6), 744-746.
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  PMID: 19169568;Abstract: This note is the first report of Bemisia tabaci (Gennadius) biotype B colonizing passionvine in Brazil. We examined the colonization of nine Passiflora species by a wild B type population under greenhouse conditions. P. amethystina Mikan was the most preferred species for oviposition and colonization, whereas P. suberosa L., P. coriacea Juss. and two commercially cultivated species, P. alata Curtis and P. edulis Sims f.flavicarpa Degener, were mostly uncolonised. P. morifolia Mast., P. cincinnata Mast., P. foetida L. and P. caerulea L. showed intermediate levels of colonization. Such differential colonization might suggest some degree of resistance by certain Passiflora species or oviposition preference by B. tabaci.
• Nunes, E. S., Brown, J. K., Moreira, A. G., Watson, G., Lourenção, A. L., Piedade, S. M., Rezende, J. A., & Vieira, M. L. (2008). First report and differential colonization of Passiflora species by the B biotype of Bemisia tabaci (Gennadius) (hemiptera: Aleyrodidae) in Brazil. Neotropical Entomology, 37(Issue 6). doi:10.1590/s1519-566x2008000600021
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  This note is the first report of Bemisia tabaci (Gennadius) biotype B colonizing passionvine in Brazil. We examined the colonization of nine Passiflora species by a wild B type population under greenhouse conditions. P. amethystina Mikan was the most preferred species for oviposition and colonization, whereas P. suberosa L., P. coriacea Juss. and two commercially cultivated species, P. alata Curtis and P. edulis Sims f.flavicarpa Degener, were mostly uncolonised. P. morifolia Mast., P. cincinnata Mast., P. foetida L. and P. caerulea L. showed intermediate levels of colonization. Such differential colonization might suggest some degree of resistance by certain Passiflora species or oviposition preference by B. tabaci.
• Papayiannis, L. C., Brown, J. K., Hadjistylli, M., & Katis, N. I. (2008). Note: Bemisia tabaci biotype B associated with tomato yellow leaf curl disease epidemics on Rhodes Island, Greece. Phytoparasitica, 36(1), 20-22.
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  Abstract: In 2006 an outbreak of tomato yellow leaf curl disease occurred in tomato crops on Rhodes Island, Greece. Diseased plants were found to be infested with the B biotype of the Bemisia tabaci (Gennadius) complex and greenhouse and open-field-grown tomato crops were infected with Tomato yellow leaf curl virus (TYLCV) introduced from the Middle East. This is the first report of TYLCV and the B biotype of B. tabaci on Rhodes Island in Greece.
• Papayiannis, L. C., Brown, J. K., Hadjistylli, M., & Katis, N. I. (2008). Note: Bemisia tabaci biotype B associated with tomato yellow leaf curl disease epidemics on Rhodes Island, Greece. Phytoparasitica, 36(Issue 1). doi:10.1007/bf02980743
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  In 2006 an outbreak of tomato yellow leaf curl disease occurred in tomato crops on Rhodes Island, Greece. Diseased plants were found to be infested with the B biotype of the Bemisia tabaci (Gennadius) complex and greenhouse and open-field-grown tomato crops were infected with Tomato yellow leaf curl virus (TYLCV) introduced from the Middle East. This is the first report of TYLCV and the B biotype of B. tabaci on Rhodes Island in Greece.
• Pietersen, G., Idris, A. M., Krüger, K., & Brown, J. K. (2008). Characterization of Tomato curly stunt virus: A new tomato-infecting begomovirus from South Africa. Plant Pathology, 57(5), 809-818.
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  Abstract: The biological and molecular characterization of a virus recognized as a distinct begomovirus species, Tomato curly stunt virus (ToCSV), first observed in South Africa in 1997, is reported here. Whitefly-transmission and host-range studies were carried out using a Bemisia tabaci colony identified as the B-biotype. The experimental host range of ToCSV spanned primarily species in the Solanaceae and Fabaceae. The complete ToCSV genome (2.766 kb) was amplified by PCR, cloned, and the DNA sequence determined. Phylogenetic analysis revealed that ToCSV was most closely related to Tobacco leaf curl Zimbabwe virus (TbLCZV), at 84% nucleotide identity, indicating that ToCSV is a new species in the genus Begomovirus that is probably endemic to southern Africa. The ToCSV genome sequence contained all of the hallmark coding and non-coding features characteristic of other previously recognized monopartite begomoviruses. ToCSV is only the second begomovirus described from southern Africa that infects solanaceous species. Neither a begomoviral DNA-B component nor a satellite-like DNA molecule was detected by PCR in extracts of ToCSV-infected plants. © 2008 The Authors.
• Pietersen, G., Idris, A. M., Krüger, K., & Brown, J. K. (2008). Characterization of Tomato curly stunt virus: A new tomato-infecting begomovirus from South Africa. Plant Pathology, 57(Issue 5). doi:10.1111/j.1365-3059.2008.01882.x
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  The biological and molecular characterization of a virus recognized as a distinct begomovirus species, Tomato curly stunt virus (ToCSV), first observed in South Africa in 1997, is reported here. Whitefly-transmission and host-range studies were carried out using a Bemisia tabaci colony identified as the B-biotype. The experimental host range of ToCSV spanned primarily species in the Solanaceae and Fabaceae. The complete ToCSV genome (2.766 kb) was amplified by PCR, cloned, and the DNA sequence determined. Phylogenetic analysis revealed that ToCSV was most closely related to Tobacco leaf curl Zimbabwe virus (TbLCZV), at 84% nucleotide identity, indicating that ToCSV is a new species in the genus Begomovirus that is probably endemic to southern Africa. The ToCSV genome sequence contained all of the hallmark coding and non-coding features characteristic of other previously recognized monopartite begomoviruses. ToCSV is only the second begomovirus described from southern Africa that infects solanaceous species. Neither a begomoviral DNA-B component nor a satellite-like DNA molecule was detected by PCR in extracts of ToCSV-infected plants. © 2008 The Authors.
• Rajaei, S. H., Kazemi, B., Manzari, S., Brown, J. K., & Sarafrazi, A. (2008). Genetic variation and mtCOI phylogeny for Bemisia tabaci (Hemiptera, Aleyrodidae) indicate that the 'B' biotype predominates in Iran. Journal of Pest Science, 81(Issue 4). doi:10.1007/s10340-008-0206-0
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  Despite a large number of investigations on the molecular genetics and population structure of the whitefly Bemisia tabaci (Gennadius) complex, no such study had been conducted in Iran. The genetic variation of B. tabaci was examined using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) for 18 field collections from cucumber, eggplant, and tomato in four provinces of Iran. PCR amplification and restriction digestion with two enzymes detected 388 RFLP fragments, of which 16 fragments showed polymorphisms. Cluster analysis of these data placed all B. tabaci individuals within a single group, and there was no evidence for between- or within-population genetic variation. Phylogenetic (Clustal W) analysis of 42 B. tabaci mtCOI sequences (n = 21 field collections) from Iran, and a comparison with well-studied haplotype or biotype reference sequences available in public sequence databases, revealed that the Iranian B. tabaci populations were most closely related to the B biotype at 0-1.2% nucleotide identity. The B biotype is a well-known member of a sister clade from the Middle East-North African region of the world, owing to its nearly worldwide distribution and invasive characteristics. This report indicates that a single major haplotype of B biotype is prevalent in Iran and that its closest relative is the B biotype. Also, given the extent of known variation in the Middle East and African continent, data indicate somewhat surprisingly that the B. tabaci collections sampled in Iran had limited genetic variation and population substructure. Knowledge that the B biotype of B. tabaci predominates in Iran is important for designing effective pest management strategies given that biotypes of B. tabaci are known to differ greatly with respect to insecticide resistance, host range, virus-vector interactions, and other key biological characteristics. © Springer-Verlag 2008.
• Rajaei, S. H., Kazemi, B., Manzari, S., Brown, J. K., & Sarafrazi, A. (2008). Genetic variation and mtCOI phylogeny for Bemisia tabaci (Hemiptera, Aleyrodidae) indicate that the 'B' biotype predominates in Iran. Journal of Pest Science, 81(4), 199-206.
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  Abstract: Despite a large number of investigations on the molecular genetics and population structure of the whitefly Bemisia tabaci (Gennadius) complex, no such study had been conducted in Iran. The genetic variation of B. tabaci was examined using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) for 18 field collections from cucumber, eggplant, and tomato in four provinces of Iran. PCR amplification and restriction digestion with two enzymes detected 388 RFLP fragments, of which 16 fragments showed polymorphisms. Cluster analysis of these data placed all B. tabaci individuals within a single group, and there was no evidence for between- or within-population genetic variation. Phylogenetic (Clustal W) analysis of 42 B. tabaci mtCOI sequences (n = 21 field collections) from Iran, and a comparison with well-studied haplotype or biotype reference sequences available in public sequence databases, revealed that the Iranian B. tabaci populations were most closely related to the B biotype at 0-1.2% nucleotide identity. The B biotype is a well-known member of a sister clade from the Middle East-North African region of the world, owing to its nearly worldwide distribution and invasive characteristics. This report indicates that a single major haplotype of B biotype is prevalent in Iran and that its closest relative is the B biotype. Also, given the extent of known variation in the Middle East and African continent, data indicate somewhat surprisingly that the B. tabaci collections sampled in Iran had limited genetic variation and population substructure. Knowledge that the B biotype of B. tabaci predominates in Iran is important for designing effective pest management strategies given that biotypes of B. tabaci are known to differ greatly with respect to insecticide resistance, host range, virus-vector interactions, and other key biological characteristics. © Springer-Verlag 2008.
• Tuttle, J. R., Idris, A. M., Brown, J. K., Haigler, C. H., & Robertson, D. (2008). Geminivirus-mediated gene silencing from cotton leaf crumple virus is enhanced by low temperature in cotton. Plant Physiology, 148(1), 41-50.
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  PMID: 18621976;PMCID: PMC2528111;Abstract: A silencing vector for cotton (Gossypium hirsutum) was developed from the geminivirus Cotton leaf crumple virus (CLCrV). The CLCrV coat protein gene was replaced by up to 500 bp of DNA homologous to one of two endogenous genes, the magnesium chelatase subunit I gene (ChlI) or the phytoene desaturase gene (PDS). Cotyledons of cotton cultivar 'Deltapine 5415' bombarded with the modified viral vectors manifested chlorosis due to silencing of either ChlI or PDS in approximately 70% of inoculated plants after 2 to 3 weeks. Use of the green fluorescence protein gene showed that replication of viral DNA was restricted to vascular tissue and that the viral vector could transmit to leaves, roots, and the ovule integument from which fibers originate. Temperature had profound effects on vector DNA accumulation and the spread of endogenous gene silencing. Consistent with reports that silencing against viruses increases at higher temperatures, plants grown at a 30°C/26°C day/night cycle had a greater than 10-fold reduction in viral DNA accumulation compared to plants grown at 22°C/18°C. However, endogenous gene silencing decreased at 30°C/26°C. There was an approximately 7 d delay in the onset of gene silencing at 22°C/18°C, but silencing was extensive and persisted throughout the life of the plant. The extent of silencing in new growth could be increased or decreased by changing temperature regimes at various times following the onset of silencing. Our experiments establish the use of the CLCrV silencing vector to study gene function in cotton and show that temperature can have a major impact on the extent of geminivirus-induced gene silencing. © 2008 American Society of Plant Biologists.
• Tuttle, J. R., Idris, A. M., Brown, J. K., Haigler, C. H., & Robertson, D. (2008). Geminivirus-mediated gene silencing from cotton leaf crumple virus is enhanced by low temperature in cotton. Plant Physiology, 148(Issue 1). doi:10.1104/pp.108.123869
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  A silencing vector for cotton (Gossypium hirsutum) was developed from the geminivirus Cotton leaf crumple virus (CLCrV). The CLCrV coat protein gene was replaced by up to 500 bp of DNA homologous to one of two endogenous genes, the magnesium chelatase subunit I gene (ChlI) or the phytoene desaturase gene (PDS). Cotyledons of cotton cultivar 'Deltapine 5415' bombarded with the modified viral vectors manifested chlorosis due to silencing of either ChlI or PDS in approximately 70% of inoculated plants after 2 to 3 weeks. Use of the green fluorescence protein gene showed that replication of viral DNA was restricted to vascular tissue and that the viral vector could transmit to leaves, roots, and the ovule integument from which fibers originate. Temperature had profound effects on vector DNA accumulation and the spread of endogenous gene silencing. Consistent with reports that silencing against viruses increases at higher temperatures, plants grown at a 30°C/26°C day/night cycle had a greater than 10-fold reduction in viral DNA accumulation compared to plants grown at 22°C/18°C. However, endogenous gene silencing decreased at 30°C/26°C. There was an approximately 7 d delay in the onset of gene silencing at 22°C/18°C, but silencing was extensive and persisted throughout the life of the plant. The extent of silencing in new growth could be increased or decreased by changing temperature regimes at various times following the onset of silencing. Our experiments establish the use of the CLCrV silencing vector to study gene function in cotton and show that temperature can have a major impact on the extent of geminivirus-induced gene silencing. © 2008 American Society of Plant Biologists.
• Brown, J. K., Burke, J. I., Hackett, R., Havis, N. D., Makepeace, J. C., & Oxley, S. J. (2007). Associations between fungal and abiotic leaf spotting and the presence of mlo alleles in barley. Plant Pathology, 56(6), 934-942. doi:10.1111/j.1365-3059.2007.01680.x
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  The hypothesis that the increased use of the powdery mildew-resistance gene mlo has caused the increase in spotting diseases of barley over the past 20 years was tested in field trials. Near-isogenic lines with alleles of the Mlo gene for susceptibility or resistance to mildew in two parental backgrounds were trialled at four sites in Scotland and two in Ireland that were prone to spotting diseases, over 3 consecutive years. Mildew was controlled by sprays with quinoxyfen. Disease levels were low in the trials, the two most important diseases being scald caused by Rhynchosporium secalis and ramularia leaf spot caused by Ramularia collo-cygni. There were high levels of abiotic spotting. Lines with mutant mlo alleles consistently developed less Rh. secalis and Ra. collo-cygni, but more abiotic spots. This study indicates that the mlo mildew-resistance gene has not alone been responsible for the rise in spotting diseases over the past 20 years. Possible reasons for the rise are discussed, including the interaction of the mlo gene with the environment.
• Brown, J. K., Olsen, M. W., Matheron, M. E., Idris, A. M., Guerrero, J. C., & Brown, J. K. (2007). Widespread Outbreak of Cucurbit yellow stunting disorder virus in Melon, Squash, and Watermelon Crops in the Sonoran Desert of Arizona and Sonora, Mexico.. Plant disease, 91(6), 773. doi:10.1094/pdis-91-6-0773a
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  Bright yellow, interveinal chlorosis was observed for the first time on leaves of the older and mid-growth of cucurbit plants in southern Arizona and Sonora (Mexico) during September and October of 2006. Some cultivars exhibited substantial yield losses of 30 to 80%. In Arizona, symptoms were in Cucumis melo (muskmelon and honeydew melon) fields in the Yuma Valley and Hyder. In Sonora, honeydew and muskmelon, Cucurbita pepo (acorn, spaghetti, and summer [yellow and zucchini] squash), and Citrullus lanatus (watermelon) were symptomatic in Hermosillo, whereas, in Caborca, honeydew and cantaloupe developed similar symptoms. Interveinal chlorosis was observed in 60 to 100% of the plants in each field. Crops planted mid-to-late season were 100% infected, whereas, the early-season fields experienced approximately 60 to 80% incidence. All symptomatic fields in the Sonoran Desert and vicinity were infested by the whitefly Bemisia tabaci (Genn.), which was identified as the 'B biotype' on the basis of mitochondria COI sequence analysis (data not shown). Whitefly population levels were variable and ranged from 5 to 200 per plant. Total RNA was isolated from leaf samples collected from symptomatic plants using Tri Reagent (Molecular Research Center, Cincinnati, OH). Purified RNA was used in reverse transcriptase-PCR with primers specific to the Cucurbit yellow stunting disorder virus (CYSDV) coat protein (CP) gene (RNA2-deoxyribonucleotide coordinates 4927-4950 and 5657-5679) for the suspected whitefly-transmitted bipartite CYSDV (4). PCR yielded the CYSDV CP fragment, at 753 bp (GenBank Accession Nos. EF21058 and EF21059), which was cloned into pGEM T-Easy and sequenced in both directions using universal primers. The CYSDV CP nucleotide sequences (n = 16) obtained from acorn squash, honeydew melon, muskmelon, yellow squash, and watermelon had 99 to 100% identity. The Arizona (AZ) and Sonora (SON) CYSDV CP sequences shared 99 to 100% identity with previously described CYSDV isolates from the Eastern Hemisphere (GenBank Accession Nos. DQ903105 and DQ903108) and also with two isolates of CYSDV collected during 2004 from Zacapa Valley, Guatemala (GenBank Accession Nos. EF21060 and EF21061) (J. K. Brown, unpublished data). CYSDV is a member of the genus Crinivirus, family Closteroviridae. CYSDV was first identified in cucumber and melon crops in the Middle East approximately 15 years ago and 10 years ago in Spain (1). Most recently, this virus was introduced into Texas (2), Guatemala (J. K. Brown, unpublished data), and Arizona and California (3). CYSDV has therefore emerged as an important and potentially worldwide threat to the production of cultivated cucurbits (3). The threat appears to be significant in light of the introduction or establishment of the exotic B. tabaci biotypes B and Q vectors, which also originated in the Middle Eastern-North African-Mediterranean region. To our knowledge, this is the first report of CYSDV infecting field-grown C. pepo (four types) and watermelon, reported previously only as experimental laboratory hosts, and of CYSDV in two types of melon (C. melo) in Mexico. References: (1) A. Celix et al. Phytopathology 86:1370, 1996. (2) J. Kao et al. Plant Dis. 84:101, 2000. (3) Y.-W. Kuo et al. Plant Dis. 91:330, 2007. (4) L. Rubio et al. J. Gen. Virol. 82:929, 2001.
• Hernández-Zepeda, C., Idris, A. M., Carnevali, G., Brown, J. K., & Moreno-Valenzuela, O. (2007). Molecular characterization and experimental host range of Euphorbia mosaic virus-Yucatan Peninsula, a begomovirus species in the Squash leaf curl virus clade. Plant Pathology, 56(5), 763-770.
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  Abstract: Euphorbia mosaic virus (EuMV), a tentative species within the genus Begomovirus, was isolated from Euphorbia heterophylla plants growing in the Yucatan Peninsula, Mexico. The complete bipartite genome was cloned from total DNA extracts and the nucleotide (nt) sequence was determined. The DNA-A sequence of the EuMV-Yucatan Peninsula (EuMV-YP) isolate shared 95% nt identity with the partially characterized type EuMV isolate from Puerto Rico. The EuMV-YP genome organization was like that of other New World, bipartite begomoviruses. The DNA-A component was 2613 nt in size, while the DNA-B component was 2602 nt long. The 165-nt common region (CR) sequence for the DNA-A and DNA-B components shared a lower than expected nt identity of 86%. The organization and iterons of the putative AC1 binding site of EuMV-YP were similar to those of begomoviruses in the Squash leaf curl virus (SLCV) clade. Characteristic disease symptoms were reproduced in E. heterophylla plants inoculated at the seedling stage using the cloned viral DNA-A and DNA-B components, confirming disease aetiology. Results of an experimental host-range study for EuMV-YP indicated that it infected at least five species in three plant families, including the Euphorbiaceae (E. heterophylla), Solanaceae (Datura stramonium, pepper, tomato) and Fabaceae (bean). Phylogenetic analysis of the DNA-A and DNA-B components indicated that EuMV-YP is a New World begomovirus and that it is a new member of the SLCV clade. © 2007 The Authors.
• Hernández-Zepeda, C., Idris, A. M., Carnevali, G., Brown, J. K., & Moreno-Valenzuela, O. A. (2007). Molecular characterization and experimental host range of Euphorbia mosaic virus-Yucatan Peninsula, a begomovirus species in the Squash leaf curl virus clade. Plant Pathology, 56(Issue 5). doi:10.1111/j.1365-3059.2007.01652.x
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  Euphorbia mosaic virus (EuMV), a tentative species within the genus Begomovirus, was isolated from Euphorbia heterophylla plants growing in the Yucatan Peninsula, Mexico. The complete bipartite genome was cloned from total DNA extracts and the nucleotide (nt) sequence was determined. The DNA-A sequence of the EuMV-Yucatan Peninsula (EuMV-YP) isolate shared 95% nt identity with the partially characterized type EuMV isolate from Puerto Rico. The EuMV-YP genome organization was like that of other New World, bipartite begomoviruses. The DNA-A component was 2613 nt in size, while the DNA-B component was 2602 nt long. The 165-nt common region (CR) sequence for the DNA-A and DNA-B components shared a lower than expected nt identity of 86%. The organization and iterons of the putative AC1 binding site of EuMV-YP were similar to those of begomoviruses in the Squash leaf curl virus (SLCV) clade. Characteristic disease symptoms were reproduced in E. heterophylla plants inoculated at the seedling stage using the cloned viral DNA-A and DNA-B components, confirming disease aetiology. Results of an experimental host-range study for EuMV-YP indicated that it infected at least five species in three plant families, including the Euphorbiaceae (E. heterophylla), Solanaceae (Datura stramonium, pepper, tomato) and Fabaceae (bean). Phylogenetic analysis of the DNA-A and DNA-B components indicated that EuMV-YP is a New World begomovirus and that it is a new member of the SLCV clade. © 2007 The Authors.
• Hernández-Zepeda, C., Idris, A. M., Carnevali, G., Brown, J. K., & Moreno-Valenzuela, O. A. (2007). Molecular characterization and phylogenetic relationships of two new bipartite begomovirus infecting malvaceous plants in Yucatan, Mexico. Virus Genes, 35(2), 369-377.
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  PMID: 17638064;Abstract: Sida acuta and Corchorus siliquosus plants showing yellow mosaic and yellow vein symptoms, respectively, were collected in the Yucatan Peninsula, Mexico. Total DNA was isolated from both plant species and used for the amplification, cloning, and sequencing of the Begomovirus genome. Nucleotide comparison of the complete DNA-A component isolated from S. acuta and C. siliquosus confirmed the presence of two distinct begomoviruses species. Based on phenotypic symptoms observed in infected field plants, the names Sida yellow mosaic Yucatan virus (SiYMYuV) and Corchorus yellow vein Yucatan virus (CoYVYuV) were proposed. The SiYMYuV DNA-A shared the highest nucleotide identity (86%) with the Okra yellow mosaic Mexico virus (OkYMMV). The complete DNA-B component shared the highest nucleotide identity (80%) with CoYVYuV. The CoYVYuV DNA-A shared the highest nucleotide identity (84%) with SiYMYuV. The 166-nt common region (CR) sequence for the DNA-A and DNA-B components of SiYMYuV shared a high nucleotide identity of 99%, and the 151 nt of CoYVYuV CR shared 95% of nucleotide identity. The organization and the iterated sequence of the putative AC1 binding site (located within the common region) of both isolates, were similar to that of the begomoviruses of the Western Hemisphere. Phylogenetic analyses placed the DNA-A and DNA-B of SiYMYuV and CoYVYuV in the clade containing the Abutilon mosaic virus (AbMV). © 2007 Springer Science+Business Media, LLC.
• Hernández-Zepeda, C., Idris, A. M., Carnevali, G., Brown, J. K., & Moreno-Valenzuela, O. A. (2007). Molecular characterization and phylogenetic relationships of two new bipartite begomovirus infecting malvaceous plants in Yucatan, Mexico. Virus Genes, 35(Issue 2). doi:10.1007/s11262-007-0080-5
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  Sida acuta and Corchorus siliquosus plants showing yellow mosaic and yellow vein symptoms, respectively, were collected in the Yucatan Peninsula, Mexico. Total DNA was isolated from both plant species and used for the amplification, cloning, and sequencing of the Begomovirus genome. Nucleotide comparison of the complete DNA-A component isolated from S. acuta and C. siliquosus confirmed the presence of two distinct begomoviruses species. Based on phenotypic symptoms observed in infected field plants, the names Sida yellow mosaic Yucatan virus (SiYMYuV) and Corchorus yellow vein Yucatan virus (CoYVYuV) were proposed. The SiYMYuV DNA-A shared the highest nucleotide identity (86%) with the Okra yellow mosaic Mexico virus (OkYMMV). The complete DNA-B component shared the highest nucleotide identity (80%) with CoYVYuV. The CoYVYuV DNA-A shared the highest nucleotide identity (84%) with SiYMYuV. The 166-nt common region (CR) sequence for the DNA-A and DNA-B components of SiYMYuV shared a high nucleotide identity of 99%, and the 151 nt of CoYVYuV CR shared 95% of nucleotide identity. The organization and the iterated sequence of the putative AC1 binding site (located within the common region) of both isolates, were similar to that of the begomoviruses of the Western Hemisphere. Phylogenetic analyses placed the DNA-A and DNA-B of SiYMYuV and CoYVYuV in the clade containing the Abutilon mosaic virus (AbMV). © 2007 Springer Science+Business Media, LLC.
• Hernández-Zepeda, C., Idris, A. M., Carnevali, G., Brown, J. K., & Moreno-Valenzuela, O. A. (2007). Preliminary identification and coat protein gene phylogenetic relationships of begomoviruses associated with native flora and cultivated plants from the Yucatan Peninsula of Mexico. Virus Genes, 35(3), 825-833.
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  PMID: 17682933;Abstract: A number of native and cultivated eudicots in the Yucatan Peninsula of Mexico (YPM) exhibit symptoms associated with virus infection. Symptomatic leaves were collected and assessed for begomoviral detection using polymerase chain reaction (PCR), and universal primers that amplify a fragment of the coat protein gene (core Cp). Begomovirus were detected in nine native and seven cultivated species, representing seven eudicot families. DNA extracts from the 16 hosts were used for PCR amplification and sequencing of a fragment containing the coat protein (Cp) gene. The complete Cp sequence was used to establish provisional species identification. Results indicated that 13 distinct begomovirus species were represented. Among these, five potentially new begomovirus species were identified, for which we propose the names Anoda golden mosaic virus (AnGMV), Boerhavia yellow spot virus (BoYSV), Papaya golden mosaic virus (PaGMV), Desmodium leaf distortion virus (DeLDV), and Hibiscus variegation virus (HiVV). Five previously described begomoviral species were provisionally identified for the first time in the YPM; these include Euphorbia mosaic virus (EuMV), Melon chlorotic leaf curl virus (MCLCuV), Okra yellow mosaic Mexico virus (OkYMMV), Sida golden mosaic virus (SiGMV), and Tobacco apical stunt virus (TbASV). Additionally, viruses previously reported from this region, Bean golden yellow mosaic virus (BGYMV), Pepper golden mosaic virus (PepGMV), and Tomato mottle virus (ToMoV) were provisionally identified in cultivated hosts. Phylogenetic analysis provisionally placed all isolates from the YPM in a Western Hemisphere begomovirus clade. © 2007 Springer Science+Business Media, LLC.
• Hernández-Zepeda, C., Idris, A. M., Carnevali, G., Brown, J. K., & Moreno-Valenzuela, O. A. (2007). Preliminary identification and coat protein gene phylogenetic relationships of begomoviruses associated with native flora and cultivated plants from the Yucatan Peninsula of Mexico. Virus Genes, 35(Issue 3). doi:10.1007/s11262-007-0149-1
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  A number of native and cultivated eudicots in the Yucatan Peninsula of Mexico (YPM) exhibit symptoms associated with virus infection. Symptomatic leaves were collected and assessed for begomoviral detection using polymerase chain reaction (PCR), and universal primers that amplify a fragment of the coat protein gene (core Cp). Begomovirus were detected in nine native and seven cultivated species, representing seven eudicot families. DNA extracts from the 16 hosts were used for PCR amplification and sequencing of a fragment containing the coat protein (Cp) gene. The complete Cp sequence was used to establish provisional species identification. Results indicated that 13 distinct begomovirus species were represented. Among these, five potentially new begomovirus species were identified, for which we propose the names Anoda golden mosaic virus (AnGMV), Boerhavia yellow spot virus (BoYSV), Papaya golden mosaic virus (PaGMV), Desmodium leaf distortion virus (DeLDV), and Hibiscus variegation virus (HiVV). Five previously described begomoviral species were provisionally identified for the first time in the YPM; these include Euphorbia mosaic virus (EuMV), Melon chlorotic leaf curl virus (MCLCuV), Okra yellow mosaic Mexico virus (OkYMMV), Sida golden mosaic virus (SiGMV), and Tobacco apical stunt virus (TbASV). Additionally, viruses previously reported from this region, Bean golden yellow mosaic virus (BGYMV), Pepper golden mosaic virus (PepGMV), and Tomato mottle virus (ToMoV) were provisionally identified in cultivated hosts. Phylogenetic analysis provisionally placed all isolates from the YPM in a Western Hemisphere begomovirus clade. © 2007 Springer Science+Business Media, LLC.
• Idris, A. M., Guerrero, J. C., & Brown, J. K. (2007). Two Distinct Isolates of Tomato yellow leaf curl virus Threaten Tomato Production in Arizona and Sonora, Mexico.. Plant disease, 91(7), 910. doi:10.1094/pdis-91-7-0910c
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  Severe yellow leaf curl and plant stunting symptoms were observed in tomato plants from two home gardens in central Arizona (Phoenix area) and a tomato field in Sonora, Mexico during the fall of 2006. Disease symptoms were reminiscent of those reported in Florida during 1994 (4) and more recently in tomato fields in the Pacific Coast state of Sinaloa, Mexico found to be infected with the exotic Tomato yellow leaf curl virus (TYLCV) (2). Total DNA was extracted from two symptomatic tomato plants from Arizona and Sonora and used as a template in PCR. PCR products of the core region of the begomovirus coat protein gene (Cp) were cloned (n = 3) and the DNA sequence was determined. BLAST analysis of the 579 bases with sequences available in the NCBI GenBank database indicated the closest match was to an isolate of the monopartite begomovirus TYLCV from Israel, which was known to have been introduced into the Caribbean region, including Puerto Rico, the southeastern United States, and Mexico from 1990 to 1996 (1,4). The full-length TYLCV genome (approximately 2,800 bases) was amplified for a field isolate from each location by rolling circle amplification (RCA) using TempliPhi (Amersham Biosciences, Piscataway, NJ). RCA products were cloned into the plasmid vector pGEM7 (Promega, Madison, WI) that had been previously digested with SacI endonuclease. The complete TYLCV genome sequence was determined for six clones from each RCA product. Nucleotide analysis indicated that the complete TYLCV genome sequences from Sonora and Arizona, respectively, shared 97.6 and 97.7% nt identity. The comparative sequence analysis indicated that TYLCV-Sonora (TYLCV-Son) (GenBank Accession No. EF210555) was 99.1% nt identical to TYLCV reported recently from Culiacan, Mexico (GenBank Accession No. DQ631892). In contrast, TYLCV-AZ (GenBank Accession No. EF210554) shared 99.3% identity with an isolate from Texas, TYLCV-TX (GenBank Accession No. EF110890) (3). Interestingly, the TX and AZ TYLCV isolates contained a unique 29-nt deletion in the intergenic region (IR) between the TATA-box and the nonanucleotide, initiating at nt coordinate 2696. Except for the deletion in the IR region of the AZ and TX isolates, these viruses shared 97.6 to 99.1% nt identity to other TYLCV isolates reported in the Western Hemisphere. The genome sequence for TYLCV-Son shares high nt identity with TYLCV isolates identified in the Yucatan Peninsula and Pacific Coast of Mexico (2), the Caribbean region, and the southeastern United States, suggesting that a single TYLCV species was introduced and has spread throughout North America and the Caribbean (4). The absence of other TYLCV isolates in the Western Hemisphere with the novel 29-nt deletion noted for the TX and AZ isolates suggests that the latter two isolates originated from the same U.S. source. In Mexico, TYLCV was first introduced in the east coast and Yucatan region approximately in 1996. From there, this isolate has spread to the western part of the country (Sinaloa and Sonora) from 2004 to 2006 (2). Similarly, in the United States, TYLCV was introduced and spread in the eastern U.S. states beginning in 1994 (4), where it had been confined until it was discovered in Texas (3) and now Arizona during 2006. References: (1) J. Bird et al. Plant Dis. 85:1028, 2001. (2) J. K. Brown and A. M. Idris. Plant Dis. 90:1360, 2006. (3) T. Isakeit et al. Plant Dis. 91:466, 2007. (4) J. E. Polston et al. Plant Dis. 78:831, 1994.
• Leke, W. N., Ramsell, J. N., Ramsell, J. N., Njualem, D. K., Titanji, V. P., Titanji, V. P., Legg, J. P., Fondong, V. N., Brown, J. K., Kvarnheden, A., & Ahmed, K. Z. (2007). FTA technology facilitates detection and identification of begomoviruses from okra plants in Cameroon.. Afr. Crop Sci. Soc, 8, 655-670.
• Maitinez-Carrillo, J. L., & Brown, J. K. (2007). Note: First report of the Q biotype of Bemisia tabaci in southern Sonora, Mexico. Phytoparasitica, 35(3), 282-284.
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  Abstract: Bemisia tabaci (Gennadius) adults were collected from poinsettia plants (Euphorbia pulcherrima) in retail nurseries in Cd. Obregon and Navojoa, Sonora, Mexico. A single field sample was collected from broccoli plants in Obregon, Sonora. Both adult whitefly and immature instars were observed on infested leaves. Whiteflies were identified as B. tabaci using morphological characters of the pupae to distinguish them from the greenhouse whitefly; and to specific biotype, by molecular analysis using the mitochondrial cytochrome oxidase I (mtCOI) sequence. Phylogenetic analysis of mtCOI sequences indicated that poinsettias were colonized both by the Q and the B biotype. The Q biotype was found only on poinsettia plants, and one poinsettia sample was infested with both the Q and the B biotype. The B biotype alone was associated with the field-collected broccoli sample analyzed in the study. A more extensive survey is required to determine the extent of the distribution of the Q biotype in Mexico, particularly where ornamental plants are transported from central to northern Mexico. Such plants could serve as the source of the Q biotype, which has been reported to be highly resistant to insecticides including the neo-nicotinoids that are widely used to control the B biotype in much of Mexico. This is the first report of the Q biotype in Mexico.
• Maitinez-Carrillo, J. L., & Brown, J. K. (2007). Note: First report of the Q biotype of Bemisia tabaci in southern Sonora, Mexico. Phytoparasitica, 35(Issue 3). doi:10.1007/bf02981162
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  Bemisia tabaci (Gennadius) adults were collected from poinsettia plants (Euphorbia pulcherrima) in retail nurseries in Cd. Obregon and Navojoa, Sonora, Mexico. A single field sample was collected from broccoli plants in Obregon, Sonora. Both adult whitefly and immature instars were observed on infested leaves. Whiteflies were identified as B. tabaci using morphological characters of the pupae to distinguish them from the greenhouse whitefly; and to specific biotype, by molecular analysis using the mitochondrial cytochrome oxidase I (mtCOI) sequence. Phylogenetic analysis of mtCOI sequences indicated that poinsettias were colonized both by the Q and the B biotype. The Q biotype was found only on poinsettia plants, and one poinsettia sample was infested with both the Q and the B biotype. The B biotype alone was associated with the field-collected broccoli sample analyzed in the study. A more extensive survey is required to determine the extent of the distribution of the Q biotype in Mexico, particularly where ornamental plants are transported from central to northern Mexico. Such plants could serve as the source of the Q biotype, which has been reported to be highly resistant to insecticides including the neo-nicotinoids that are widely used to control the B biotype in much of Mexico. This is the first report of the Q biotype in Mexico.
• Qiu, B., Coats, S. A., Ren, S., Idris, A. M., Caixia, X. u., & Brown, J. K. (2007). Phylogenetic relationships of native and introduced Bemisia tabaci (Homoptera: Aleyrodidae) from China and India based on mtCOI DNA sequencing and host plant comparisons. Progress in Natural Science, 17(6), 645-654.
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  Abstract: Phylogenetic relationships for Bemisia tabaci were reconstructed by analysis of a -780 bp fragment of the mitochondrial cytochrome oxidase I (mtCOI) gene with an emphasis on geographic range and distribution among eight eudicot plant families that are common hosts of B. tabaci worldwide to elucidate key phylogeographic linkages between populations extant in China (n=31) and India (n=34). Bootstrap values for the Maximum Parsimony tree were highly robust for all major nodes involving the major Asian clade, subgroups, and sister groups within, at 92%-100%. Between-clade distances for the Southeast Asia and three other major clades, e.g. from sub-Sahara Africa, North Africa-Mediterranean, and the Americas, were approximately >16% divergent. Two major Asian subgroups (I, II) were resolved, which represented populations indigenous to the region, comprising two (Ia, Ib) and five (II a-e) sister groups, respectively, which diverged by 11%. Two distinct populations from sunflower in Hyderabad grouped separately within the two Asian subgroups. All other populations grouped uniquely within Asian subgroup II or I. The B biotype was identified in 23 collections from China at 97.3%-99.5% nucleotide identity with B biotype reference sequences; it was not identified in collections from India. The majority of haplotypes were associated with 3-4 plant families, with one exception that for sister group IId (sesame, India), it might be monophagous. Thus, B. tabaci from the southeastern and near eastern regions of the Asian continent comprise of a large number of ancestral, richly divergent, mostly polyphagous populations. This region is therefore hypothesized to constitute an important Old World center of diversification for the B. tabaci complex, together with sub-Saharan Africa.
• Qiu, B., Coats, S. A., Ren, S., Idris, A. M., Xu, C., & Brown, J. K. (2007). Phylogenetic relationships of native and introduced Bemisia tabaci (Homoptera: Aleyrodidae) from China and India based on mtCOI DNA sequencing and host plant comparisons. Progress in Natural Science, 17(Issue 6). doi:10.1080/10002007088537453
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  Phylogenetic relationships for Bemisia tabaci were reconstructed by analysis of a -780 bp fragment of the mitochondrial cytochrome oxidase I (mtCOI) gene with an emphasis on geographic range and distribution among eight eudicot plant families that are common hosts of B. tabaci worldwide to elucidate key phylogeographic linkages between populations extant in China (n=31) and India (n=34). Bootstrap values for the Maximum Parsimony tree were highly robust for all major nodes involving the major Asian clade, subgroups, and sister groups within, at 92%-100%. Between-clade distances for the Southeast Asia and three other major clades, e.g. from sub-Sahara Africa, North Africa-Mediterranean, and the Americas, were approximately >16% divergent. Two major Asian subgroups (I, II) were resolved, which represented populations indigenous to the region, comprising two (Ia, Ib) and five (II a-e) sister groups, respectively, which diverged by 11%. Two distinct populations from sunflower in Hyderabad grouped separately within the two Asian subgroups. All other populations grouped uniquely within Asian subgroup II or I. The B biotype was identified in 23 collections from China at 97.3%-99.5% nucleotide identity with B biotype reference sequences; it was not identified in collections from India. The majority of haplotypes were associated with 3-4 plant families, with one exception that for sister group IId (sesame, India), it might be monophagous. Thus, B. tabaci from the southeastern and near eastern regions of the Asian continent comprise of a large number of ancestral, richly divergent, mostly polyphagous populations. This region is therefore hypothesized to constitute an important Old World center of diversification for the B. tabaci complex, together with sub-Saharan Africa.
• Sunter, G., Isakeit, T., Idris, A. M., Brown, J. K., & Black, M. C. (2007). Tomato yellow leaf curl virus in Tomato in Texas, Originating from Transplant Facilities.. Plant disease, 91(4), 466. doi:10.1094/pdis-91-4-0466a
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  Tomato yellow leaf curl virus (TYLCV), a monopartite virus in the genus Begomovirus (family, Geminiviridae) from the Middle East, is one of the most damaging whitefly-transmitted viruses of tomato (Lycopersicon esculentum) worldwide. TYLCV was first identified in the United States in 1997 in Florida (4), and most recently, in the Pacific Coast states of Mexico where fresh market tomatoes are grown for the U.S. market (1). During September 2006, tomatoes grown from transplants in Waller County, TX exhibited shortened internodes, stunting and puckering of leaflets, green vein banding, and diffuse chlorosis. The disease incidence in two fields (4 ha total) was 95% and yield was substantially reduced. Many of the transplants were symptomatic at planting. The transplants originated from two facilities in Hidalgo County, TX. Both facilities had experienced heavy infestations of the whitefly, Bemisia tabaci (Genn.), during transplant production. At the same time, transplants produced in Uvalde and Bexar counties, TX, where whitefly infestations were also prevalent, had similar virus symptoms. Total DNA was extracted from the leaves of symptomatic tomato plants from 10 samples from these four counties and amplified by PCR (2). DNA samples from Waller, Hidalgo, and Uvalde counties were cloned, and a partial fragment of the viral coat protein gene (core Cp) was sequenced. BLAST analysis of the core Cp sequences of each sample confirmed the presence of TYLCV. No other begomovirus was detected, and all attempts to amplify a bipartite begomovirus by PCR using degenerate DNA-B specific primers (3) were unsuccessful. The full-length TYLCV DNA was amplified from three samples using the rolling circle amplification method as described (1), cloned, and the sequences were determined. The three sequences shared 99.6 to 100% nt identity and so only one sequence was deposited in the NCBI GenBank database (Accession No. EF110890) (1). Analysis of the complete genome nucleotide sequence corroborated TYLCV identity predicted by core Cp analysis that was 98.1% identical with TYLCV from Egypt (GenBank Accession No. AY594174) and Spain (GenBank Accession No. AJ489258), 97.6% with TYLCV from Mexico (GenBank Accession No. DQ631892), and 96.5% with TYLCV-Is (GenBank Accession No. X15656). Additionally, a Southern blot with TYLCV as the probe detected replicating (double-stranded) TYLCV DNA in all samples consisting of three plants from Uvalde County and 21 plants from Bexar County. To our knowledge, this is the first report of TYLCV in Texas that occurred in two transplant production areas approximately 400 km apart. Transplants produced in Uvalde and Bexar counties were planted there, while Hidalgo County transplants were shipped outside of the usual range of the whitefly. Hidalgo County has a subtropical climate, which can allow overwintering of TYLCV and the whitefly vector, allowing the establishment and spread of this virus in the future. References: (1) J. K. Brown and A. M. Idris. Plant Dis. 90:1360, 2006. (2) J. K. Brown et al. Arch. Virol. 146:1581, 2001. (3) A. M. Idris and J. K. Brown. Phytopathology 88:648, 1998. (4) J. E. Polston et al. Plant Dis. 83:984, 1999.
• Tuttle, J. R., Tuttle, J. R., Idris, A. M., Haigler, C. H., Brown, J. K., & Robertson, D. (2007). Using virus-induced gene silencing and gene expression as tools to understand geminivirus infection in cotton plants.. Journal of Cotton Science.
• Bayhan, E., Ulusoy, M. R., & Brown, J. K. (2006). Effects of different cucurbit species and temperature on selected life history traits of the 'B' biotype of Bemisia tabaci. Phytoparasitica, 34(Issue 3). doi:10.1007/bf02980950
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  The development time and survival rate were determined at three constant temperatures for the 'B' biotype of Bemisia tabaci on cucumber (Beit Alpha F1), cantaloupe (Anzer F1), squash (Sakiz F1), and watermelon (Galactica F1). The development time for immature stages at 20, 25 and 30 ± 1°C was, respectively, 33.5, 19.3 and 16.8 days on cucumber; 36.5, 20.8 and 19.60 days on cantaloupe; 37.2, 20.1 and 19.8 days on squash; and 38.9, 23.8 and 21.9 days on watermelon. At 20, 25 and 30°C, the respective percentage survival of immature instars was 73.2, 83.2 and 72.9% on cucumber; 72.9, 84.9 and 75.6% on cantaloupe; 52.1, 76.1 and 57.5% on squash; and 37.6, 64.8 and 40.1% on watermelon.
• Bayhan, E., Ulusoy, M. R., & Brown, J. K. (2006). Effects of different cucurbit species and temperature on selected life history traits of the 'B' biotype of Bemisia tabaci. Phytoparasitica, 34(3), 235-242.
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  Abstract: The development time and survival rate were determined at three constant temperatures for the 'B' biotype of Bemisia tabaci on cucumber (Beit Alpha F1), cantaloupe (Anzer F1), squash (Sakiz F1), and watermelon (Galactica F1). The development time for immature stages at 20, 25 and 30 ± 1°C was, respectively, 33.5, 19.3 and 16.8 days on cucumber; 36.5, 20.8 and 19.60 days on cantaloupe; 37.2, 20.1 and 19.8 days on squash; and 38.9, 23.8 and 21.9 days on watermelon. At 20, 25 and 30°C, the respective percentage survival of immature instars was 73.2, 83.2 and 72.9% on cucumber; 72.9, 84.9 and 75.6% on cantaloupe; 52.1, 76.1 and 57.5% on squash; and 37.6, 64.8 and 40.1% on watermelon.
• Bayhan, E., Ulusoy, M. R., & Brown, J. K. (2006). Host range, distribution, and natural enemies of Bemisia tabaci 'B biotype' (Hemiptera: Aleyrodidae) in Turkey. Journal of Pest Science, 79(Issue 4). doi:10.1007/s10340-006-0139-4
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  The whitefly Bemisia tabaci (Gennadius) has caused notable damage to vegetable and cotton crops in the eastern Mediterranean region since about 1994, and has become particularly problematic in southern Turkey beginning in 2000. The development of squash silverleaf symptoms in Cucurbita species and the unprecedented high population levels in the region suggested that the B biotype, notable for the latter phenotypes, had been introduced. To test this hypothesis and determine the host distribution of the suspect introduced B biotype and its associated natural enemies, B. tabaci immature instars and adults, and the associated natural enemies were collected from cultivated and uncultivated plant species. From the southern Turkey collections, B. tabaci was found to colonize 152 species from 43 plant families. Of the plant species upon which B. tabaci was found to reproduce, 152 of them were reported as hosts of B. tabaci in Turkey. Five species of predators and two species of parasitoids were identified as natural enemies of the B biotype of B. tabaci in southern Turkey. Using the mitochondrial cytochrome oxidase I gene all B. tabaci were identified as the B biotype of the B. tabaci complex, at 96-100% shared identity with reference B biotype sequences. Results indicate that this invasive biotype has displaced the local Turkey-cotton haplotype that was known to occur previously in southern Turkey. © Springer-Verlag 2006.
• Bayhan, E., Ulusoy, M. R., & Brown, J. K. (2006). Host range, distribution, and natural enemies of Bemisia tabaci 'B biotype' (Hemiptera: Aleyrodidae) in Turkey. Journal of Pest Science, 79(4), 233-240.
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  Abstract: The whitefly Bemisia tabaci (Gennadius) has caused notable damage to vegetable and cotton crops in the eastern Mediterranean region since about 1994, and has become particularly problematic in southern Turkey beginning in 2000. The development of squash silverleaf symptoms in Cucurbita species and the unprecedented high population levels in the region suggested that the B biotype, notable for the latter phenotypes, had been introduced. To test this hypothesis and determine the host distribution of the suspect introduced B biotype and its associated natural enemies, B. tabaci immature instars and adults, and the associated natural enemies were collected from cultivated and uncultivated plant species. From the southern Turkey collections, B. tabaci was found to colonize 152 species from 43 plant families. Of the plant species upon which B. tabaci was found to reproduce, 152 of them were reported as hosts of B. tabaci in Turkey. Five species of predators and two species of parasitoids were identified as natural enemies of the B biotype of B. tabaci in southern Turkey. Using the mitochondrial cytochrome oxidase I gene all B. tabaci were identified as the B biotype of the B. tabaci complex, at 96-100% shared identity with reference B biotype sequences. Results indicate that this invasive biotype has displaced the local Turkey-cotton haplotype that was known to occur previously in southern Turkey. © Springer-Verlag 2006.
• Bouharroud, R., Hanafi, A., Brown, J. K., & Serghini, M. A. (2006). Resistance and cross-resistance of Bemisia tabaci to three commonly used insecticides in the tomato greenhouses of the Souss Valley of Morocco. European Journal of Scientific Research, 14(4), 587-594.
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  Abstract: In this study, 10 populations of whiteflies B. tabaci were collected from tomato greenhouses in the Souss valley of Morocco and bioassayed for resistance to three commonly used insecticides (Imidacloprid, Thaimethoxam and Methomyl). Using Leaf-Dip bioassay, we concluded that all populations tested were resistant to Imidacloprid and Thiamethoxam. The resistance factors registered were varied between 2 to 39 and 2 to 12, respectively. The levels of resistance to Methomyl were slightly low and showed a moderate variation between 1 and 4. The analyses of correlation showed a very significant cross-resistance of B. tabaci to this two Neonicotinoids. The predominant biotype noted in this study is biotype Q with the presence of some B. tabaci populations expressed a variant of biotype Q. © EuroJournals Publishing, Inc. 2006.
• Bouharroud, R., Hanafi, A., Brown, J. K., & Serghini, M. A. (2006). Resistance and cross-resistance of Bemisia tabaci to three commonly used insecticides in the tomato greenhouses of the Souss Valley of Morocco. European Journal of Scientific Research, 14(Issue 4).
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  In this study, 10 populations of whiteflies B. tabaci were collected from tomato greenhouses in the Souss valley of Morocco and bioassayed for resistance to three commonly used insecticides (Imidacloprid, Thaimethoxam and Methomyl). Using Leaf-Dip bioassay, we concluded that all populations tested were resistant to Imidacloprid and Thiamethoxam. The resistance factors registered were varied between 2 to 39 and 2 to 12, respectively. The levels of resistance to Methomyl were slightly low and showed a moderate variation between 1 and 4. The analyses of correlation showed a very significant cross-resistance of B. tabaci to this two Neonicotinoids. The predominant biotype noted in this study is biotype Q with the presence of some B. tabaci populations expressed a variant of biotype Q. © EuroJournals Publishing, Inc. 2006.
• Chu, D., Zhang, Y., Brown, J. K., Cong, B., Xu, B., Wu, Q., & Zhu, G. (2006). The introduction of the exotic Q biotype of Bemisia tabaci from the Mediterranean region into China on ornamental crops. Florida Entomologist, 89(2), 168-174.
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  Abstract: The Q biotype of Bemisia tabaci (Gennadius), which has been described from the Mediterranean/North African region, was identified for the first time infesting ornamental crop species in several locations in China. Identification and partial distributions of the exotic B biotype and the recently introduced Q biotype in China were established by using the mitochondrial cytochrome oxidase I gene (mtCOI) as a molecular marker. Collections of B. tabaci were made from representative geographical locations and plant hosts in different provinces of China. MtCOI sequence analysis revealed that collections from Beijing [AY582872, AY589499], Yunnan [AY518189, AY587516], and Henan [AY587514] shared >99.6% sequence identity with the Q biotype from Spain [AY587513, AY562216, AY596950]. The Q type from China shared 98.9-99.4% nucleotide sequence identity with Q-like relatives of B. tabaci described from Israel [AY518191, AY582869]. Phylogenetic analyses indicated that certain B. tabaci populations that are present in China are the Q biotype, and that the Q biotype now in China may have originated from Spain or other nearby locations where the Q biotype has been identified. This is the first report of the introduction of the Q biotype from the Mediterranean region into China. The specific outcomes of the Q biotype as an invasive species in Asia are presently unknown. Certain Q biotype populations from Spain have been reported to exhibit resistant to neonicotinoid insecticides, which are commonly used for controlling this pest and virus vector in ornamental and field crops. Thus, the close monitoring of the Q biotype in China and elsewhere, particularly where commercial plants are grown for export or received for importation, respectively, is essential to avoid the further geographical expansion of the habitat of the Q biotype.
• Idris, A. M., & Brown, J. K. (2006). Introduction of the Exotic Monopartite Tomato yellow leaf curl virus into West Coast Mexico.. Plant disease, 90(10), 1360. doi:10.1094/pd-90-1360a
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  Leaf curl symptoms that are reminiscent of begomovirus (genus Begomovirus, family Geminiviridae) infection were observed widespread in the tomato crop during the early fall 2005 through the spring 2006 growing seasons in Sinaloa State, Mexico. Symptoms were widespread in three major valleys (Culiacan, Guasave, and Los Mochis) that are largely dedicated to fresh-market tomato production for the U.S. market from October to June. Symptoms included stunting of leaves, shortened internodes, distortion of leaf margins, and green vein banding. Fruit set was reduced significantly (as much as 90%) on the portion of the plant that developed above the point of symptom expression. Tomato fields were heavily infested with the B biotype of the whitefly Bemisia tabaci (Genn.) vector and no other insect vectors were noted in the fields. Total DNA was extracted from six symptomatic tomato plants (two from each valley) and used as template to amplify, clone, and sequence the core region of the begomovirus CP. BLAST analysis of begomovirus sequences available in the NCBI GenBank database indicated the closest match was the Old World monopartite begomovirus Tomato yellow leaf curl virus (TYLCV) from Israel (Accession No. X15656) at 97.8% shared nucleotide (nt) identity. The full-length genome was amplified for each of six isolates using TempliPhi (Amersham Biosciences, Piscataway, NJ) and cloned into the pGEM7 vector (Promega, Madison, WI). The complete DNA genome sequence was determined for eight clones by primer walking. Cloned TempliPhi products sequenced represented two to three isolates from each valley. Results indicated that the isolates (n = 8) were 98.9 to 100% identical (Accession No. DQ631892) to each other, and they shared 98% identity with TYLCV isolates reported from the Caribbean Region and Florida. This highly virulent begomovirus of tomato, originating in Israel, was first reported in Mexico from 1996 to 1997 when it was identified in tomato plants in the Yucatan Peninsula (1) (>1,500 miles from Sinaloa). The latter report followed the introduction of TYLCV in tomato seedlings from Florida into several eastern U.S. states (3,4) and then into Puerto Rico (2). The introduction of TYLCV into Sinaloa where tomato production is highly concentrated is significant because the region supplies the majority (as much as 93%) of fresh-market tomatoes to the western United States from October to June (>$750 million dollars). Of equal importance is the immediate proximity of the pandemic to California where more than 90% of the processing tomatoes in the United States are grown. References: (1) J. T. Ascencio-Ibáñez et al. Plant Dis. 83:1178, 1999. (2) J. Bird et al. Plant Dis. 85:1028, 2001. (3) M. T. Momol et al. Plant Dis 83:487, 1999. (4) J. E. Polston and P. K. Anderson, Plant Dis. 81:1358, 1997.
• Idris, A. M., Brown, J. K., & Abdel-salam, A. M. (2006). Introduction of the New World Squash leaf curl virus to Squash (Cucurbita pepo) in Egypt: A Potential Threat to Important Food Crops.. Plant disease, 90(9), 1262. doi:10.1094/pd-90-1262b
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  Squash plants showing leaf curling, yellow mottling, and reduced fruit set were observed in fields in Giza, Egypt in spring 2005. These particular symptoms had not been observed previously in zucchini squash plants in Egypt, but were reminiscent of those caused by begomoviruses (Geminiviridae) that are known to occur in the region, including Watermelon chlorotic stunt virus. Squash plants were heavily infested with the whitefly Bemisia tabaci (Genn.), the only known vector of begomoviruses. Total nucleic acids were isolated from symptomatic squash leaves using the cetyltrimethylammoniumbromide method, and extracts were subjected to polymerase chain reaction (PCR) analysis using two sets of PCR primers. One primer set (prAV2644 and prAC1154) was designed to amplify a fragment that contains the entire viral coat protein (Cp), while the second primer set (prBV1855 and prBC656) was designed to amplify the common region (CR) of DNA-B of begomoviruses (1). The expected size fragments were cloned and the sequence was determined for five clones each. Unexpectedly, the Cp and the CR-B fragments shared their highest nucleotide sequence (nt) identity among well-characterized begomoviruses to the bipartite Squash leaf curl virus (SLCV) native to the western United States. A third primer set (prAC344 and prAV1134) (1) was subsequently used to amplify the remainder of the putative SLCV DNA-A. The fragment was cloned and the DNA sequence was determined. Assembly of the overlapping DNA-A fragments resulted in a complete DNA-A component sequence of 2,636 nt, which is identical to the expected size of the SLCV DNA-A component (GenBank Accession No. DQ285019). Comparison with the latter sequence indicated that the Egyptian squash isolate shared 98% nt identity with SLCV. The sequence for the DNA-B fragment (1,162 nt) shared 94% nt identity with SLCV and was deposited in GenBank as Accession No. DQ285020. The high-shared nt identity with SLCV (2) from the United States suggests that this isolate, herein SLCV-EG, has been introduced into Egypt. The relatively low DNA-B nt sequence identity was a not a surprise since this component is normally less conserved even between strains of a single begomoviral species. Introduction of SLCV is not only potentially significant to the domestic production of crop species in the Cucurbitaceae but also for legume crops. SLCV has a broad host range that also includes members of the Fabaceae, which includes species that contribute significant sources of protein for much of Egypt's population. The virus thus far is thought to be present only in Lower Egypt, however, it could feasibly threaten legume and cucurbit crops if it spreads to Upper Egypt. To our knowledge, this is the first begomovirus of New World origin to become established in the Old World. References: (1) A. M. Idris and J. K. Brown. Phytopathology 88:648, 1998. (2) S. G. Lazarowitz. Virology 180:70, 1991.
• Leshkowitz, D., Gazit, S., Reuveni, E., Ghanim, M., Czosnek, H., McKenzie, C., Shatters Jr., R. L., & Brown, J. K. (2006). Whitefly (Bemisia tabaci) genome project: Analysis of sequenced clones from egg, instar, and adult (viruliferous and non-viruliferous) cDNA libraries. BMC Genomics, 7.
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  PMID: 16608516;PMCID: PMC1488848;Abstract: Background: The past three decades have witnessed a dramatic increase in interest in the whitefly Bemisia tabaci, owing to its nature as a taxonomically cryptic species, the damage it causes to a large number of herbaceous plants because of its specialized feeding in the phloem, and to its ability to serve as a vector of plant viruses. Among the most important plant viruses to be transmitted by B. tabaci are those in the genus Begomovirus (family, Geminiviridae). Surprisingly, little is known about the genome of this whitefly. The haploid genome size for male B. tabaci has been estimated to be approximately one billion bp by flow cytometry analysis, about five times the size of the fruitfly Drosophila melanogaster. The genes involved in whitefly development, in host range plasticity, and in begomovirus vector specificity and competency, are unknown. Results: To address this general shortage of genomic sequence information, we have constructed three cDNA libraries from non-viruliferous whiteflies (eggs, immature instars, and adults) and two from adult insects that fed on tomato plants infected by two geminiviruses: Tomato yellow leaf curl virus (TYLCV) and Tomato mottle virus (ToMoV). In total, the sequence of 18,976 clones was determined. After quality control, and removal of 5,542 clones of mitochondrial origin 9,110 sequences remained which included 3,843 singletons and 1,017 contigs. Comparisons with public databases indicated that the libraries contained genes involved in cellular and developmental processes. In addition, approximately 1,000 bases aligned with the genome of the B. tabaci endosymbiotic bacterium Candidatus Portiera aleyrodidarum, originating primarily from the egg and instar libraries. Apart from the mitochondrial sequences, the longest and most abundant sequence encodes vitellogenin, which originated from whitefly adult libraries, indicating that much of the gene expression in this insect is directed toward the production of eggs. Conclusion: This is the first functional genomics project involving a hemipteran (Homopteran) insect from the subtropics/tropics. The B. tabaci sequence database now provides an important tool to initiate identification of whitefly genes involved in development, behaviour, and B. tabaci-mediated begomovirus transmission. © 2006 Leshkowitz et al; licensee BioMed Central Ltd.
• Leshkowitz, D., Gazit, S., Reuveni, E., Ghanim, M., Czosnek, H., McKenzie, C., Shatters, R. L., & Brown, J. K. (2006). Whitefly (Bemisia tabaci) genome project: Analysis of sequenced clones from egg, instar, and adult (viruliferous and non-viruliferous) cDNA libraries. BMC Genomics, 7(Issue). doi:10.1186/1471-2164-7-79
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  Background: The past three decades have witnessed a dramatic increase in interest in the whitefly Bemisia tabaci, owing to its nature as a taxonomically cryptic species, the damage it causes to a large number of herbaceous plants because of its specialized feeding in the phloem, and to its ability to serve as a vector of plant viruses. Among the most important plant viruses to be transmitted by B. tabaci are those in the genus Begomovirus (family, Geminiviridae). Surprisingly, little is known about the genome of this whitefly. The haploid genome size for male B. tabaci has been estimated to be approximately one billion bp by flow cytometry analysis, about five times the size of the fruitfly Drosophila melanogaster. The genes involved in whitefly development, in host range plasticity, and in begomovirus vector specificity and competency, are unknown. Results: To address this general shortage of genomic sequence information, we have constructed three cDNA libraries from non-viruliferous whiteflies (eggs, immature instars, and adults) and two from adult insects that fed on tomato plants infected by two geminiviruses: Tomato yellow leaf curl virus (TYLCV) and Tomato mottle virus (ToMoV). In total, the sequence of 18,976 clones was determined. After quality control, and removal of 5,542 clones of mitochondrial origin 9,110 sequences remained which included 3,843 singletons and 1,017 contigs. Comparisons with public databases indicated that the libraries contained genes involved in cellular and developmental processes. In addition, approximately 1,000 bases aligned with the genome of the B. tabaci endosymbiotic bacterium Candidatus Portiera aleyrodidarum, originating primarily from the egg and instar libraries. Apart from the mitochondrial sequences, the longest and most abundant sequence encodes vitellogenin, which originated from whitefly adult libraries, indicating that much of the gene expression in this insect is directed toward the production of eggs. Conclusion: This is the first functional genomics project involving a hemipteran (Homopteran) insect from the subtropics/tropics. The B. tabaci sequence database now provides an important tool to initiate identification of whitefly genes involved in development, behaviour, and B. tabaci-mediated begomovirus transmission. © 2006 Leshkowitz et al; licensee BioMed Central Ltd.
• Rivera-bustamante, R. F., Holguin-pena, R. J., Brown, J. K., & Arguello-astorga, G. R. (2006). A New Strain of Tomato chino La Paz virus Associated with a Leaf Curl Disease of Tomato in Baja California Sur, Mexico.. Plant disease, 90(7), 973. doi:10.1094/pd-90-0973b
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  Since 2001, geminivirus-like disease symptoms have been observed in tomato plants on the Baja California Peninsula of Mexico. These diseases have been associated with large populations of Bemisia tabaci (Genn.) in commercial fields and have caused dramatic decreases in expected yields. Leaf samples from tomato plants displaying symptoms of stunting and severe upward leaf curling were collected in March 2002 in fields located near the city of La Paz, Baja California Sur (BCS). Total DNA was extracted and tested for the presence of geminiviral DNA using polymerase chain reaction (PCR) with begomovirus-specific degenerate primer pairs PALIv1978/PARIc494 and PALIc1978/PARIv494 (4). PCR products of the expected size (~1.16 and ~1.45 kb) were obtained, cloned into pGEM-T Easy (Promega, Madison, WI), and sequenced. Restriction fragment length polymorphism analysis of the PCR fragments was performed using EcoRI, HindIII, PstI, and XbaI. Restriction fragment patterns were the same for all amplicons and no evidence of mixed infection was obtained. In addition, experimental transmission by whiteflies and inoculations by biolistics consistently induced severe leaf epinasty and stunted growth on tomato seedlings. The complete (2,606 nt) DNA-A sequence of the infecting virus was determined (GenBank Accession No. AY339618) and compared with viral sequences available at GenBank-EMBL databases using BLASTN and the CLUSTAL program (MegAlign, DNASTAR, Madison, WI). The highest nucleotide identity was obtained with the recently described Tomato chino Baja California virus, ToChBCV (90.2%, GenBank Accession No. AY339619), isolated from tomato plantings in El Carrizal, BCS, 100 km from La Paz (3). The second and third best scores were obtained with Tomato severe leaf curl virus from Nicaragua (ToSLCV-NI, 79.6%, GenBank Accession No. AJ508784) and Guatemala (ToSLCV-GT94, 73.8%, GenBank Accession No. AF130415), respectively. Overall, sequence similarity with other New World begomoviruses was rather low (less than 70% identity). Careful analysis of differences between the La Paz isolate and its closest relative, ToChBCV from El Carrizal, revealed that they display different Ori-associated iterons (i.e., replication (Rep)-binding sites) having GGAGTA and GGGTCY core sequences, respectively (1). Moreover, sequence comparisons of the Rep-binding domain (aa 1-120) showed that these domains are only 71% identical. Current taxonomic criteria for begomoviruses establishes that a virus DNA-A sequence identity below 89% with its closest relative is indicative of a separate species (2). Since the La Paz and El Carrizal isolates share 90.2% nt identity, they should be considered strains of a same virus species, recently renamed Tomato chino La Paz virus, ToChLPV (2). Nevertheless, the remarkable differences in their putative replication specificity determinants suggest that ToChLPV and ToChLPV-[BCS] could be incompatible in replication, an interesting issue that should be experimentally addressed. References: (1) G. R. Arguello-Astorga et al. Virology 203:90, 1994. (2) C. Fauquet and J. Stanley. Arch. Virol. 150:2151, 2005. (3) R. J. Holguín-Peña et al. Plant Dis. 89:341, 2005. (4) M. R. Rojas et al. Plant Dis. 77:340, 1993.
• Sseruwagi, P., Maruthi, M. N., Colvin, J., Rey, M. E., Brown, J. K., & Legg, J. P. (2006). Colonization of non-cassava plant species by cassava whiteflies (Bemisia tabaci) in Uganda. Entomologia Experimentalis et Applicata, 119(2), 145-153.
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  Abstract: Bemisia tabaci (Genn.) (Homoptera: Aleyrodidae) is the vector of cassava mosaic geminiviruses (CMGs), which are the main production constraint to cassava [Manihot esculenta Crantz (Euphorbiaceae)], both in Uganda and elsewhere in Africa. Two B. tabaci genotype clusters, Ug1 and Ug2, differentiated at 8% nucleotide (nt) divergence within the mitochondrial cytochrome oxidase I (mtCOI) gene, have been shown to occur on cassava in Uganda. However, the role of alternative hosts in the ecology of cassava B. tabaci genotypes and their possible involvement in the epidemiology of cassava mosaic disease (CMD) in Uganda remain unknown. In this study, we investigated the restriction of cassava B. tabaci genotypes to cassava and the colonization of alternative host species in select cassava-growing areas of the country in 2003 and 2004. Bemisia tabaci adults and 4th instar nymphs were collected from cassava and 11 other cultivated and uncultivated species occurring adjacent to the sampled cassava fields. Phylogenetic analysis of mtCOI sequences revealed that only a single genotype cluster, Ug1, was present on both cassava and non-cassava plant species sampled in this study. The Ug1 genotypes (n = 49) shared 97-99% nt identity with the previously described cassava-associated B. tabaci populations in southern Africa, and were ∼8% and ∼13% divergent from Ug2 and the 'Ivory Coast cassava' genotypes in Uganda and Ivory Coast, respectively. The Ug1 genotypes occurred (as adults) on all 12 source-plant species sampled. However, based on the presence of B. tabaci 4th instar nymphs, the Ug1 genotypes (n = 13) colonized cassava and five other non-cassava plant species: Manihot glaziovii, Jatropha gossypifolia, Euphorbia heterophylla, Aspilia africana, and Abelmoschus esculentus, suggesting that cassava B. tabaci (Ug1 genotypes) are not restricted to cassava in Uganda. No Ug2-like genotypes were detected on any of the plant species sampled, including cassava, in this study. The identification of additional hosts for at least one genotype cluster, Ug1, known also to colonize cassava, and which was hitherto thought to be 'cassava-restricted' may have important epidemiological significance for the spread of CMGs in Uganda. © 2006 The Netherlands Entomological Society.
• Sseruwagi, P., Maruthi, M. N., Colvin, J., Rey, M. E., Brown, J. K., & Legg, J. P. (2006). Colonization of non-cassava plant species by cassava whiteflies (Bemisia tabaci) in Uganda. Entomologia Experimentalis et Applicata, 119(Issue 2). doi:10.1111/j.1570-7458.2006.00402.x
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  Bemisia tabaci (Genn.) (Homoptera: Aleyrodidae) is the vector of cassava mosaic geminiviruses (CMGs), which are the main production constraint to cassava [Manihot esculenta Crantz (Euphorbiaceae)], both in Uganda and elsewhere in Africa. Two B. tabaci genotype clusters, Ug1 and Ug2, differentiated at 8% nucleotide (nt) divergence within the mitochondrial cytochrome oxidase I (mtCOI) gene, have been shown to occur on cassava in Uganda. However, the role of alternative hosts in the ecology of cassava B. tabaci genotypes and their possible involvement in the epidemiology of cassava mosaic disease (CMD) in Uganda remain unknown. In this study, we investigated the restriction of cassava B. tabaci genotypes to cassava and the colonization of alternative host species in select cassava-growing areas of the country in 2003 and 2004. Bemisia tabaci adults and 4th instar nymphs were collected from cassava and 11 other cultivated and uncultivated species occurring adjacent to the sampled cassava fields. Phylogenetic analysis of mtCOI sequences revealed that only a single genotype cluster, Ug1, was present on both cassava and non-cassava plant species sampled in this study. The Ug1 genotypes (n = 49) shared 97-99% nt identity with the previously described cassava-associated B. tabaci populations in southern Africa, and were ∼8% and ∼13% divergent from Ug2 and the 'Ivory Coast cassava' genotypes in Uganda and Ivory Coast, respectively. The Ug1 genotypes occurred (as adults) on all 12 source-plant species sampled. However, based on the presence of B. tabaci 4th instar nymphs, the Ug1 genotypes (n = 13) colonized cassava and five other non-cassava plant species: Manihot glaziovii, Jatropha gossypifolia, Euphorbia heterophylla, Aspilia africana, and Abelmoschus esculentus, suggesting that cassava B. tabaci (Ug1 genotypes) are not restricted to cassava in Uganda. No Ug2-like genotypes were detected on any of the plant species sampled, including cassava, in this study. The identification of additional hosts for at least one genotype cluster, Ug1, known also to colonize cassava, and which was hitherto thought to be 'cassava-restricted' may have important epidemiological significance for the spread of CMGs in Uganda. © 2006 The Netherlands Entomological Society.
• Ueda, S., & Brown, J. K. (2006). First report of the Q biotype of Bemisia tabaci in Japan by mitochondrial cytochrome oxidase I sequence analysis. Phytoparasitica, 34(4), 405-411.
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  Abstract: The recent upsurgence of Bemisia tabaci (Genn.) as an important insect pest and vector of Tomato yellow leaf curl virus (TYLCV) is directly linked to serious damage to tomato crops grown throughout Japan. The molecular genetic identification and phylogenetic relationships of 12 B. tabaci populations collected from representative locations in Japan were determined based on the mitochondrial cytochrome oxidase I (mtCOI) sequence. Phylogenetic analysis of the whitefly mtCOI sequence indicated that both the invasive B and Q biotypes now occur in Japan. The Q biotype was found at four locations: Mihara in Hiroshima, Nishigoshi in Kumamoto, Miyanojo and Okuchi in Kagoshima prefectures; the remaining eight collections were identified as the B biotype. This is the first report of the introduction of Q biotype in Japan.
• Ueda, S., & Brown, J. K. (2006). First report of the Q biotype of Bemisia tabaci in Japan by mitochondrial cytochrome oxidase I sequence analysis. Phytoparasitica, 34(Issue 4). doi:10.1007/bf02981027
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  The recent upsurgence of Bemisia tabaci (Genn.) as an important insect pest and vector of Tomato yellow leaf curl virus (TYLCV) is directly linked to serious damage to tomato crops grown throughout Japan. The molecular genetic identification and phylogenetic relationships of 12 B. tabaci populations collected from representative locations in Japan were determined based on the mitochondrial cytochrome oxidase I (mtCOI) sequence. Phylogenetic analysis of the whitefly mtCOI sequence indicated that both the invasive B and Q biotypes now occur in Japan. The Q biotype was found at four locations: Mihara in Hiroshima, Nishigoshi in Kumamoto, Miyanojo and Okuchi in Kagoshima prefectures; the remaining eight collections were identified as the B biotype. This is the first report of the introduction of Q biotype in Japan.
• Zhu, G. R., Zhang, Y., Xu, B. Y., Wu, Q. J., Cong, B., Chu, D., & Brown, J. K. (2006). THE INTRODUCTION OF THE EXOTIC Q BIOTYPE OF BEMISIA TABACI FROM THE MEDITERRANEAN REGION INTO CHINA ON ORNAMENTAL CROPS. Florida Entomologist, 89(2), 168-174. doi:10.1653/0015-4040(2006)89[168:tioteq]2.0.co;2
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  Abstract The Q biotype of Bemisia tabaci (Gennadius), which has been described from the Mediterranean/North African region, was identified for the first time infesting ornamental crop species in several locations in China. Identification and partial distributions of the exotic B biotype and the recently introduced Q biotype in China were established by using the mitochondrial cytochrome oxidase I gene (mtCOI) as a molecular marker. Collections of B. tabaci were made from representative geographical locations and plant hosts in different provinces of China. MtCOI sequence analysis revealed that collections from Beijing [AY582872, AY589499], Yunnan [AY518189, AY587516], and Henan [AY587514] shared >99.6% sequence identity with the Q biotype from Spain [AY587513, AY562216, AY596950]. The Q type from China shared 98.9-99.4% nucleotide sequence identity with Q-like relatives of B. tabaci described from Israel [AY518191, AY582869]. Phylogenetic analyses indicated that certain B. tabaci populations that are pres...
• Bayhan, E., Ölmez-Bayhan, S., Ulusoy, M. R., & Brown, J. K. (2005). Effect of temperature on the biology of Aphis punicae (Passerini) (Homoptera: Aphididae) on Pomegranate. Environmental Entomology, 34(1), 22-26.
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  Abstract: The effect of temperature on development time, reproductive capacity, and rate of survival for Aphis punicae was studied at five different (constant) temperatures (17.5, 20, 22.5, 25, and 27.5°C). The development period for immature instar stages ranged from 11.72 d at 17.5°C to 4.30 d at 27.5°C. The lowest developmental threshold was 11.8°C, and the thermal constant (K) was 66.4 DD. The percentage survivorship of immature stages varied from 72.0 to 90.0% over a temperature range of 17.5-27.5°C. The average longevity of adult females was 16.50, 17.17, 18.16, 12.04, and 8.91 d at temperatures of 17.5, 20, 22.5, 25, and 27.5°C, respectively. The average number of offspring produced by a single female was 14.65, 22.68, 31.34, 21.31, and 11.27 at temperatures of 17.5, 20, 22.5, 25, and 27.5°C, respectively. The greatest rm (0.3292) was observed at 25°C. The optimal temperature for A. punicae growth, development, and reproduction was 22.5-25°C.
• Bayhan, E., Ölmez-Bayhan, S., Ulusoy, M. R., & Brown, J. K. (2005). Effect of temperature on the biology of Aphis punicae (Passerini) (Homoptera: Aphididae) on Pomegranate. Environmental Entomology, 34(Issue 1). doi:10.1603/0046-225x-34.1.22
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  The effect of temperature on development time, reproductive capacity, and rate of survival for Aphis punicae was studied at five different (constant) temperatures (17.5, 20, 22.5, 25, and 27.5°C). The development period for immature instar stages ranged from 11.72 d at 17.5°C to 4.30 d at 27.5°C. The lowest developmental threshold was 11.8°C, and the thermal constant (K) was 66.4 DD. The percentage survivorship of immature stages varied from 72.0 to 90.0% over a temperature range of 17.5-27.5°C. The average longevity of adult females was 16.50, 17.17, 18.16, 12.04, and 8.91 d at temperatures of 17.5, 20, 22.5, 25, and 27.5°C, respectively. The average number of offspring produced by a single female was 14.65, 22.68, 31.34, 21.31, and 11.27 at temperatures of 17.5, 20, 22.5, 25, and 27.5°C, respectively. The greatest rm (0.3292) was observed at 25°C. The optimal temperature for A. punicae growth, development, and reproduction was 22.5-25°C.
• Brown, J. K., & Idris, A. M. (2005). Genetic differentiation of whitefly Bemisia tabaci mitochondrial cytochrome oxidase I, and phylogeographic concordance with the coat protein of the plant virus genus Begomovirus. Annals of the Entomological Society of America, 98(6), 827-837.
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  Abstract: Phylogenetic analysis of the Bemisia tabaci (Gennadius) mitochondrial cytochrome oxidase I (mtCOI) sequence grouped populations into one of four major phylogeographic lineages, represented as groups from The Americas-Caribbean Basin (New World) (n = 41), Mediterranean-North Africa-Middle East (n = 47), Asia-Australia (n = 52), and Sub-Saharan Africa (n = 29). The mean genetic variation and percentage nucleotide identities indicated that whitefly populations from the Southeast Asian/ Australian region were the most genetically divergent (1% per lineage/ 106 yr), whereas the Western Hemisphere (Americas-Caribbean region) populations exhibited the lowest degrees of divergence. The phylogenetic tree for the genus Begomovirus (Geminviridae) coat protein (CP) revealed two major phylogeographic lineages with a basis either in the Eastern or Western Hemisphere, respectively. Within the Eastern Hemisphere lineage, the viral CP grouped in one of the three major geographical regions, which were analogous to the mtCOI for the respective geographically associated whitefly populations. Analysis of the CP for the Western Hemisphere viruses revealed two sublineages representative of the 1) North and Central Americas/Caribbean Basin, and 2) South American continent, respectively, which also were phylogeographically concordant with the two major Western Hemisphere B. tabaci mtCOI groups. Analysis of the base substitution rates and synonymous and nonsynonymous changes for the B. tabaci mtCOI coding region suggested that this gene has evolved under positive selection. In total, 26 polymorphic sites (11%) were identified for the species complex, and the fixation of certain amino acids was more evident within certain lineages or populations than others. Collectively, the majority of the 26 polymorphic sites were located at the C-terminal end of the mtCOI fragment that was examined herein. Of the 26 polymorphic sites, only two were net charge-altering amino acids (Y407H and G486K). The genetic differentiation coefficient (GST) for the B. tabaci complex was 59.9%, suggesting that at least moderate genetic differentiation has occurred for the four major extant phylogeographic lineages. This observation is in line with available extant biotic (exclusive vector of begomoviruses; transmission determinants linked to viral CP), morphological (no unique characters), and genetic evidence (single group based on mtCOI, 16SrDNA, and ITS-1 analysis), which supports the hypothesis that B. tabaci comprises a single albeit, cryptic species. Taxonomically, B. tabaci is a species complex, which likely has and continues to experience restricted gene flow in part as the result of geographical and/or host range restrictions. © 2005 Entomological Society of America.
• Brown, J. K., & Idris, A. M. (2005). Genetic differentiation of whitefly Bemisia tabaci mitochondrial cytochrome oxidase I, and phylogeographic concordance with the coat protein of the plant virus genus Begomovirus. Annals of the Entomological Society of America, 98(Issue 6). doi:10.1603/0013-8746(2005)098[0827:gdowbt]2.0.co;2
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  Phylogenetic analysis of the Bemisia tabaci (Gennadius) mitochondrial cytochrome oxidase I (mtCOI) sequence grouped populations into one of four major phylogeographic lineages, represented as groups from The Americas-Caribbean Basin (New World) (n = 41), Mediterranean-North Africa-Middle East (n = 47), Asia-Australia (n = 52), and Sub-Saharan Africa (n = 29). The mean genetic variation and percentage nucleotide identities indicated that whitefly populations from the Southeast Asian/ Australian region were the most genetically divergent (1% per lineage/ 106 yr), whereas the Western Hemisphere (Americas-Caribbean region) populations exhibited the lowest degrees of divergence. The phylogenetic tree for the genus Begomovirus (Geminviridae) coat protein (CP) revealed two major phylogeographic lineages with a basis either in the Eastern or Western Hemisphere, respectively. Within the Eastern Hemisphere lineage, the viral CP grouped in one of the three major geographical regions, which were analogous to the mtCOI for the respective geographically associated whitefly populations. Analysis of the CP for the Western Hemisphere viruses revealed two sublineages representative of the 1) North and Central Americas/Caribbean Basin, and 2) South American continent, respectively, which also were phylogeographically concordant with the two major Western Hemisphere B. tabaci mtCOI groups. Analysis of the base substitution rates and synonymous and nonsynonymous changes for the B. tabaci mtCOI coding region suggested that this gene has evolved under positive selection. In total, 26 polymorphic sites (11%) were identified for the species complex, and the fixation of certain amino acids was more evident within certain lineages or populations than others. Collectively, the majority of the 26 polymorphic sites were located at the C-terminal end of the mtCOI fragment that was examined herein. Of the 26 polymorphic sites, only two were net charge-altering amino acids (Y407H and G486K). The genetic differentiation coefficient (GST) for the B. tabaci complex was 59.9%, suggesting that at least moderate genetic differentiation has occurred for the four major extant phylogeographic lineages. This observation is in line with available extant biotic (exclusive vector of begomoviruses; transmission determinants linked to viral CP), morphological (no unique characters), and genetic evidence (single group based on mtCOI, 16SrDNA, and ITS-1 analysis), which supports the hypothesis that B. tabaci comprises a single albeit, cryptic species. Taxonomically, B. tabaci is a species complex, which likely has and continues to experience restricted gene flow in part as the result of geographical and/or host range restrictions. © 2005 Entomological Society of America.
• Brown, J. K., Idris, A. M., Ostrow, K. M., Goldberg, N., French, R., & Stenger, D. C. (2005). Genetic and phenotypic variation of the Pepper golden mosaic virus complex. Phytopathology, 95(10), 1217-1224.
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  PMID: 18943475;Abstract: Three isolates of the bipartite begomovirus Pepper golden mosaic virus (PepGMV) were characterized for genomic and biological properties. The complete nucleotide sequences of the DNA-A and DNA-B components were determined from infectious clones of PepGMV-Serrano (PepGMV-Ser), PepGMV-Mosaic (PepGMV-Mo), and PepGMV-Distortion (PepGMV-D). Nucleotide sequence identity among PepGMV components ranged from 91 to 96% for DNA-A and from 84 to 99% for DNA-B, with each PepGMV component most closely related to the corresponding component of Cabbage leaf curl virus (CaLCV). However, phylogenetic relationships among begomovirus components were incongruent because DNA-A of PepGMV and CaLCV share an inferred evolutionary history distinct from that of DNA-B. The cloned components of PepGMV-Ser, -Mo, and -D were infectious by biolistic inoculation to pepper but differed in symptom expression: PepGMV-Ser exhibited a bright golden mosaic, PepGMV-Mo produced a yellow-green mosaic, and PepGMV-D caused only a mild mosaic and foliar distortion followed by a "recovery" phenotype in which leaves developing after initial symptom expression appeared normal. Differences in symptoms also were observed on tomato, tobacco, and Datura stramonium. Progeny virus derived from clones of PepGMV-Ser and -Mo were transmitted from pepper to pepper by the B biotype of Bemisia tabaci; progeny virus derived from PepGMV-D clones was not transmissible by the B biotype. Reassortant genomes derived from heterologous DNA components of the three isolates were infectious in all possible pairwise combinations, with symptom phenotype in pepper determined by the DNA-B component. Collectively, these results indicate that the three virus isolates examined may be considered distinct strains of PepGMV that have the capacity to exchange genetic material.
• Brown, J. K., Idris, A. M., Ostrow, K. M., Goldberg, N., French, R., & Stenger, D. C. (2005). Genetic and phenotypic variation of the Pepper golden mosaic virus complex. Phytopathology, 95(Issue 10). doi:10.1094/phyto-95-1217
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  Three isolates of the bipartite begomovirus Pepper golden mosaic virus (PepGMV) were characterized for genomic and biological properties. The complete nucleotide sequences of the DNA-A and DNA-B components were determined from infectious clones of PepGMV-Serrano (PepGMV-Ser), PepGMV-Mosaic (PepGMV-Mo), and PepGMV-Distortion (PepGMV-D). Nucleotide sequence identity among PepGMV components ranged from 91 to 96% for DNA-A and from 84 to 99% for DNA-B, with each PepGMV component most closely related to the corresponding component of Cabbage leaf curl virus (CaLCV). However, phylogenetic relationships among begomovirus components were incongruent because DNA-A of PepGMV and CaLCV share an inferred evolutionary history distinct from that of DNA-B. The cloned components of PepGMV-Ser, -Mo, and -D were infectious by biolistic inoculation to pepper but differed in symptom expression: PepGMV-Ser exhibited a bright golden mosaic, PepGMV-Mo produced a yellow-green mosaic, and PepGMV-D caused only a mild mosaic and foliar distortion followed by a "recovery" phenotype in which leaves developing after initial symptom expression appeared normal. Differences in symptoms also were observed on tomato, tobacco, and Datura stramonium. Progeny virus derived from clones of PepGMV-Ser and -Mo were transmitted from pepper to pepper by the B biotype of Bemisia tabaci; progeny virus derived from PepGMV-D clones was not transmissible by the B biotype. Reassortant genomes derived from heterologous DNA components of the three isolates were infectious in all possible pairwise combinations, with symptom phenotype in pepper determined by the DNA-B component. Collectively, these results indicate that the three virus isolates examined may be considered distinct strains of PepGMV that have the capacity to exchange genetic material.
• Brown, J. K., Lambert, G. M., Ghanim, M., Czosnek, H., & Galbraith, D. W. (2005). Nuclear DNA content of the whitefly Bemisia tabaci (Aleyrodidae: Hemiptera) estimated by flow cytometry. Bulletin of Entomological Research, 95(4), 309-312.
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  PMID: 16048678;Abstract: The nuclear DNA content of the whitefly Bemisia tabaci (Gennnadius) was estimated using flow cytometry. Male and female nuclei were stained with propidium iodide and their DNA content was estimated using chicken red blood cells and Arabidopsis thaliana L. (Brassicaceae) as external standards. The estimated nuclear DNA content of male and female B. tabaci was 1.04 and 2.06 pg, respectively. These results corroborated previous reports based on chromosome counting, which showed that B. tabaci males are haploid and females are diploid. Conversion between DNA content and genome size (1 pg DNA = 980 Mbp) indicate that the haploid genome size of B. tabaci is 1020 Mbp, which is approximately five times the size of the genome of the fruitfly Drosophila melanogaster Meigen. These results provide an important baseline that will facilitate genomics-based research for the B. tabaci complex. © CAB International, 2005.
• Brown, J. K., Lambert, G. M., Ghanim, M., Czosnek, H., & Galbraith, D. W. (2005). Nuclear DNA content of the whitefly Bemisia tabaci (Aleyrodidae: Hemiptera) estimated by flow cytometry. Bulletin of Entomological Research, 95(Issue 4). doi:10.1079/ber2005361
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  The nuclear DNA content of the whitefly Bemisia tabaci (Gennnadius) was estimated using flow cytometry. Male and female nuclei were stained with propidium iodide and their DNA content was estimated using chicken red blood cells and Arabidopsis thaliana L. (Brassicaceae) as external standards. The estimated nuclear DNA content of male and female B. tabaci was 1.04 and 2.06 pg, respectively. These results corroborated previous reports based on chromosome counting, which showed that B. tabaci males are haploid and females are diploid. Conversion between DNA content and genome size (1 pg DNA = 980 Mbp) indicate that the haploid genome size of B. tabaci is 1020 Mbp, which is approximately five times the size of the genome of the fruitfly Drosophila melanogaster Meigen. These results provide an important baseline that will facilitate genomics-based research for the B. tabaci complex. © CAB International, 2005.
• Dennehy, T. J., Degain, B. A., Harpold, V. S., Brown, J. K., Morin, S., Fabrick, J. A., Byrne, F. J., Nichols, R. L., & Fabrick, J. A. (2005). New Challenges to Management of Whitefly Resistance to Insecticides in Arizona. The University of Arizona Cooperative Extension, Vegetable Report, Series P-144, 31.
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  We report on susceptibility to insecticides of whiteflies (Bemisia tabaci) collected from cotton, melons and ornamental plans during the 2004 season. No major problems with field performance of insecticides against whiteflies were observed or reported in 2004 in Arizona cotton, vegetables, or melons. However, monitoring revealed further statewide reduction in susceptibility to pyriproxyfen (Knack®) and showed that whiteflies possessing pyriproxyfen resistance could be detected in all low desert areas of the state. Susceptibility to buprofezin (Applaud®/Courier®) has not changed significantly since 1997. Mean susceptibility to synergized pyrethroids (e.g., Danitol® + Orthene®) has increased strikingly on a statewide basis since 1995 though highly resistant whiteflies were detected in some collections from cotton, melons and ornamentals. Whiteflies from throughout Arizona continued to be highly susceptible to imidacloprid (Admire®/Provado®). However, susceptibility to the related neonicotinoid insecticide, acetamiprid (Intruder®) varied widely and was lowest in collections from melons and greenhouse plants. Whiteflies from cotton that were least susceptibile to acetamiprid were significantly less susceptible to a second neonicotinoid, thiamethoxam (Actara®/Centric®/Platinum®). The most worrisome findings of our 2004 studies stemmed from detection of a strain of B tabaci, at a retail nursery, that was essentially unaffected by pyriproxyfen in egg bioassays. It also possessed strikingly reduced susceptibility to acetamiprid, buprofezin, mixtures of fenpropathrin and acephate, imidacloprid, and thiamethoxam. This strain was found to be a biotype of B. tabaci previously undescribed in the US, the Q biotype. We cannot predict with accuracy the timecourse of future resistance problems or the spread and impact of this new whitefly biotype. However, our findings point to the need to formulate contingency plans for management of resistance, in order to insure that Arizona agriculture does not revisit the severe whitefly control problems experienced in the past.
• Fauquet, C. M., Sawyer, S., Idris, A. M., & Brown, J. K. (2005). Sequence analysis and classification of apparent recombinant begomoviruses infecting tomato in the Nile and Mediterranean Basins. Phytopathology, 95(5), 549-555.
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  PMID: 18943321;Abstract: Numerous whitefly-transmitted viral diseases of tomato have emerged in countries around the Nile and Mediterranean Basins the last 20 years. These diseases are caused by monopartite geminiviruses (family Geminiviridae) belonging to the genus Begomovirus that probably resulted from numerous recombination events. The molecular biodiversity of these viruses was investigated to better appreciate the role and importance of recombination and to better clarify the phylogenetic relationships and classification of these viruses. The analysis partitioned the tomato-infecting begomoviruses from this region into two major clades, Tomato yellow leaf curl virus and Tomato yellow leaf curl Sardinia virus. Phylogenetic and pairwise analyses together with an evaluation for gene conversion were performed from which taxonomic classification and virus biodiversity conclusions were drawn. Six recombination hotspots and three homogeneous zones within the genome were identified among the tomato-infecting isolates and species examined here, suggesting that the recombination events identified were not random occurrences. © 2005 The American Phytopathological Society.
• Fauquet, C. M., Sawyer, S., Idris, A. M., & Brown, J. K. (2005). Sequence analysis and classification of apparent recombinant begomoviruses infecting tomato in the Nile and Mediterranean Basins. Phytopathology, 95(Issue 5). doi:10.1094/phyto-95-0549
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  Numerous whitefly-transmitted viral diseases of tomato have emerged in countries around the Nile and Mediterranean Basins the last 20 years. These diseases are caused by monopartite geminiviruses (family Geminiviridae) belonging to the genus Begomovirus that probably resulted from numerous recombination events. The molecular biodiversity of these viruses was investigated to better appreciate the role and importance of recombination and to better clarify the phylogenetic relationships and classification of these viruses. The analysis partitioned the tomato-infecting begomoviruses from this region into two major clades, Tomato yellow leaf curl virus and Tomato yellow leaf curl Sardinia virus. Phylogenetic and pairwise analyses together with an evaluation for gene conversion were performed from which taxonomic classification and virus biodiversity conclusions were drawn. Six recombination hotspots and three homogeneous zones within the genome were identified among the tomato-infecting isolates and species examined here, suggesting that the recombination events identified were not random occurrences. © 2005 The American Phytopathological Society.
• Idris, A. M., & Brown, J. K. (2005). Evidence for interspecific-recombination for three monopartite begomoviral genomes associated with the tomato leaf curl disease from central Sudan. Archives of Virology, 150(5), 1003-1012.
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  PMID: 15703848;Abstract: Two distinct viral genotypes were identified in the same tomato plant collected from Gezira, Sudan and are provisionally designated Tomato leaf curl Sudan virus (ToLCSDV-Gez) and Tomato yellow leaf curl virus-Sudan (TYLCV-SD). A third genotype was identified in tomato samples collected in Shambat, Sudan (ToLCSDV-Sha). The ToLCSDV-Gez and ToLCSDV-Sha isolates were ∼90% identical, TYLCV-SD from Gezira shared ∼93% identity with TYLCV-Mld. Recombination analyses identified two fragments in the ToLCSDV-Gez and TYLCV-SD genomes, providing evidence that these two genomes had undergone intermolecular recombination. A half unit size (737 nt) single-stranded satellite DNA was associated with ToLCSDV-Gez and TYLCV-SD. © Springer-Verlag 2005.
• Idris, A. M., & Brown, J. K. (2005). Evidence for interspecific-recombination for three monopartite begomoviral genomes associated with the tomato leaf curl disease from central Sudan. Archives of Virology, 150(Issue 5). doi:10.1007/s00705-004-0484-7
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  Two distinct viral genotypes were identified in the same tomato plant collected from Gezira, Sudan and are provisionally designated Tomato leaf curl Sudan virus (ToLCSDV-Gez) and Tomato yellow leaf curl virus-Sudan (TYLCV-SD). A third genotype was identified in tomato samples collected in Shambat, Sudan (ToLCSDV-Sha). The ToLCSDV-Gez and ToLCSDV-Sha isolates were ∼90% identical, TYLCV-SD from Gezira shared ∼93% identity with TYLCV-Mld. Recombination analyses identified two fragments in the ToLCSDV-Gez and TYLCV-SD genomes, providing evidence that these two genomes had undergone intermolecular recombination. A half unit size (737 nt) single-stranded satellite DNA was associated with ToLCSDV-Gez and TYLCV-SD. © Springer-Verlag 2005.
• Idris, A. M., Briddon, R. W., Bull, S. E., & Brown, J. K. (2005). Cotton leaf curl Gezira virus-satellite DNAs represent a divergent, geographically isolated Nile Basin lineage: Predictive identification of a satDNA REP-binding motif. Virus Research, 109(1), 19-32.
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  PMID: 15826909;Abstract: Cotton leaf curl Gezira virus (CLCuGV), a species of the genus Begomovirus (family Geminiviridae), was recently cloned from cotton, okra, and Sida alba plants exhibiting leaf-curling and vein-thickening symptoms in Sudan. Here, we describe a previously unknown lineage of single-stranded DNA satellite (satDNA) molecules, which are associated with CLCuGV, and are required for development of characteristic disease symptoms. Co-inoculation of cotton and Nicotiana benthamiana plants with satDNAs cloned from cotton, okra, and S. alba, together with CLCuGV as the 'helper virus' resulted in the development of characteristic leaf-curling and vein-thickening symptoms in both hosts. An anatomical study of symptomatic, virus-infected cotton leaves revealed that spongy parenchyma cells had developed instead of collenchyma cells at the sites of vein thickening. Phylogenetically, the CLCuGV-associated satDNAs from Sudan, together with their closest relatives from Egypt, form a new satDNA lineage comprising only satDNAs from the Upper and Lower Nile Basins. Analysis of satellites and their helper virus sequences identified a predicted REP-binding site consisting of the directly repeated sequence, 'CGGTACTCA', and an inverted repeated sequence, 'TGAGTACCG', which occur in the context of a 17-nucleotide motif. The conserved REP-binding motif identified herein, together with strict geographic isolation, and apparent host-restriction, may be the collective hallmark of these new satDNA-begomovirus lineages, extant in the Nile Basin. © 2004 Elsevier B.V. All rights reserved.
• Idris, A. M., Briddon, R. W., Bull, S. E., & Brown, J. K. (2005). Cotton leaf curl Gezira virus-satellite DNAs represent a divergent, geographically isolated Nile Basin lineage: Predictive identification of a satDNA REP-binding motif. Virus Research, 109(Issue 1). doi:10.1016/j.virusres.2004.10.002
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  Cotton leaf curl Gezira virus (CLCuGV), a species of the genus Begomovirus (family Geminiviridae), was recently cloned from cotton, okra, and Sida alba plants exhibiting leaf-curling and vein-thickening symptoms in Sudan. Here, we describe a previously unknown lineage of single-stranded DNA satellite (satDNA) molecules, which are associated with CLCuGV, and are required for development of characteristic disease symptoms. Co-inoculation of cotton and Nicotiana benthamiana plants with satDNAs cloned from cotton, okra, and S. alba, together with CLCuGV as the 'helper virus' resulted in the development of characteristic leaf-curling and vein-thickening symptoms in both hosts. An anatomical study of symptomatic, virus-infected cotton leaves revealed that spongy parenchyma cells had developed instead of collenchyma cells at the sites of vein thickening. Phylogenetically, the CLCuGV-associated satDNAs from Sudan, together with their closest relatives from Egypt, form a new satDNA lineage comprising only satDNAs from the Upper and Lower Nile Basins. Analysis of satellites and their helper virus sequences identified a predicted REP-binding site consisting of the directly repeated sequence, 'CGGTACTCA', and an inverted repeated sequence, 'TGAGTACCG', which occur in the context of a 17-nucleotide motif. The conserved REP-binding motif identified herein, together with strict geographic isolation, and apparent host-restriction, may be the collective hallmark of these new satDNA-begomovirus lineages, extant in the Nile Basin. © 2004 Elsevier B.V. All rights reserved.
• Musser, R. O., Cipollini, D. F., Hum-Musser, S. M., Williams, S. A., Brown, J. K., & Felton, G. W. (2005). Evidence that the caterpillar salivary enzyme glucose oxidase provides herbivore offense in solanaceous plants. Archives of Insect Biochemistry and Physiology, 58(2), 128-137.
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  PMID: 15660363;Abstract: The insect salivary enzyme glucose oxidase (GOX) can inhibit wound-inducible nicotine production in tobacco, Nicotiana tabacum. We examined whether salivary gland extracts of Helicoverpa zea lacking active GOX could still suppress nicotine in tobacco, Nicotiana tabacum, and whether GOX could suppress wound-inducible defenses of another Solanaceous plant, tomato Lycopersicon esculentum. Tobacco leaves were wounded with a cork borer and treated with water, salivary gland extracts with active GOX (SxG), or salivary gland extracts with inactive GOX (SxI). After three days, leaves treated with SxG had significantly less nicotine than all other wounded treatments. Neonates that fed on the terminal leaves of tobacco plants treated with SxG had significantly higher survival than neonates that fed on leaves treated with either SxI or water. This evidence supports the assertion that GOX is the salivary factor responsible for the suppression of tobacco plant nicotine production by H. zea saliva. Results for the NahG tobacco plants, which lack salicylic acid (SA) due to a transgene for bacterial SA hydroxylase, indicate that suppression of nicotine by GOX does not require SA. However, tobacco leaves that were wounded and treated with SxG had significantly higher levels of the SA-mediated PR-1a protein than leaves treated with SxI or water. Leaves of tomato plants wounded with scissors and then treated with SxG had trypsin inhibitor levels that were moderately lower than plants wounded and treated with purified GOX, water, or SxI. However, all the wounded tomato leaves irrespective of treatment resulted in lower caterpillar growth rates than the non-wounded tomato leaves. Glucose oxidase is the first insect salivary enzyme shown to suppress wound-inducible herbivore defenses of plants. © 2005 Wiley-Liss, Inc.
• Musser, R. O., Kwon, H. S., Williams, S. A., White, C. J., Romano, M. A., Holt, S. M., Bradbury, S., Brown, J. K., & Felton, G. W. (2005). Evidence that caterpillar labial saliva suppresses infectivity of potential bacterial pathogens. Archives of Insect Biochemistry and Physiology, 58(2), 138-144.
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  PMID: 15660360;Abstract: Salivary enzyme, glucose oxidase (GOX) from the caterpillar Helicoverpo zeo, catalyzes the conversion of glucose to gluconic acid and hydrogen peroxide. Because hydrogen peroxide has well-known antimicrobial properties, we examined whether caterpillar labial saliva could reduce the infectivity of bacterial pathogens. We examined the effects of caterpillar saliva on the growth of two bacteria species Serratia marcescens and Pseudomonas aeruginosa. Wells formed in LB agar contained a solution of salivary gland extract (Sx) and glucose, GOX and glucose, Sx only, GOX only, or glucose only. After 18 h of incubation, the diameter of cleared bacteria was measured. Wells treated with only GOX, Sx, or glucose showed no measurable area of clearing, while wells treated with GOX with glucose or Sx with glucose had considerable clearing. To determine if saliva could provide protection to caterpillars in vivo, a surgery was performed on caterpillars that prevented the secretion of labial saliva. Caterpillars were fed a diet containing either no added bacteria or treated with high levels of S. marcescens or P. aeruginosa. Caterpillars that could not secrete saliva had significantly higher levels of mortality when feeding on diet treated with either bacterium than caterpillars that could secrete saliva when feeding on equal levels of bacteria-treated diet. Our evidence demonstrates for the first time that insect saliva in situ can provide protection against bacterial pathogens and that the salivary enzyme GOX appears to provide the antimicrobial properties. © 2005 Wiley-Liss, Inc.
• Sseruwagi, P., Legg, J. P., Maruthi, M. N., Colvin, J., Rey, M. E., & Brown, J. K. (2005). Genetic diversity of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) populations and presence of the B biotype and a non-B biotype that can induce silver-leaf symptoms in squash, in Uganda. Annals of Applied Biology, 147(3), 253-265.
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  Abstract: The extent of genetic variability and host-plant distribution of Bemisia tabaci (Gennadius) genotypes colonising cultivated and uncultivated plant species occurring adjacent to cassava fields in selected cassava-producing areas of Uganda in 2003/04 were investigated using the mitochondrial cytochrome oxidase I (mtCOI) gene as the molecular marker. Eight genotype clusters, Ug1-Ug8, which are supported by high bootstrap values (≥80), at 3-18% nt divergence, were revealed among the collective Ugandan B. tabaci populations. Ug1 and Ug2 (both cassava-associated) and Ug8 (sweetpotato-associated) have been reported previously in Uganda. Ug3 was genetically dissimilar to B. tabaci described elsewhere and colonised a single species, Ocimum gratissimum. Ug4-Ug7 formed four closely related subclusters (93-97% nt identity) and diverged by 15-18% from Ug1, Ug2, Ug3 and Ug8, respectively. Ug4 had as its closest relatives (at 97-99% nt identity) the Ivory Coast okra biotype, whereas genotypes Ug5 and Ug6 had as their closest relatives (at 95-99% and 99% nt identity, respectively) the Mediterranean-North Africa-Middle East (MEDNAFR-ME) biotypes, which also include the well-studied B and Q biotypes. Ug7 was closely related (at 98-99% nt identity) to biotype Ms from the Reunion Island in the Indian Ocean. Ug4 colonised Cucurbita pepo, Cucurbita sativus, Leonotis nepetifolia and Pavonia urens, while Ug7 colonised Commelina benghalensis, Gossypium hirsutum and Phaseolus vulgaris. Ug6, the B-biotype-like genotype colonised Abelmoschus esculentus and C. benghalensis only. None of Ug4-Ug7 genotypes was found associated with, or colonising, cassava or sweetpotato plants. In addition to colonising sweetpotato, the Ug8 genotypes colonised Lycopersicon esculentum and L. nepetifolia. Ug6 and Ug7, both members of the B biotype/B-like cluster, induced silverleaf symptoms on Cucurbita sp. The discovery of five previously identified B. tabaci genotype clusters, Ug3-Ug7, in Uganda, among which are some of the world's most economically important biotypes, namely B and Q, is particularly significant in the spread of gemini-viruses with devastating effects to crop production in Africa. © 2005 The Authors.
• Sseruwagi, P., Legg, J. P., Maruthi, M. N., Colvin, J., Rey, M. E., & Brown, J. K. (2005). Genetic diversity of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) populations and presence of the B biotype and a non-B biotype that can induce silver-leaf symptoms in squash, in Uganda. Annals of Applied Biology, 147(Issue 3). doi:10.1111/j.1744-7348.2005.00026.x
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  The extent of genetic variability and host-plant distribution of Bemisia tabaci (Gennadius) genotypes colonising cultivated and uncultivated plant species occurring adjacent to cassava fields in selected cassava-producing areas of Uganda in 2003/04 were investigated using the mitochondrial cytochrome oxidase I (mtCOI) gene as the molecular marker. Eight genotype clusters, Ug1-Ug8, which are supported by high bootstrap values (≥80), at 3-18% nt divergence, were revealed among the collective Ugandan B. tabaci populations. Ug1 and Ug2 (both cassava-associated) and Ug8 (sweetpotato-associated) have been reported previously in Uganda. Ug3 was genetically dissimilar to B. tabaci described elsewhere and colonised a single species, Ocimum gratissimum. Ug4-Ug7 formed four closely related subclusters (93-97% nt identity) and diverged by 15-18% from Ug1, Ug2, Ug3 and Ug8, respectively. Ug4 had as its closest relatives (at 97-99% nt identity) the Ivory Coast okra biotype, whereas genotypes Ug5 and Ug6 had as their closest relatives (at 95-99% and 99% nt identity, respectively) the Mediterranean-North Africa-Middle East (MEDNAFR-ME) biotypes, which also include the well-studied B and Q biotypes. Ug7 was closely related (at 98-99% nt identity) to biotype Ms from the Reunion Island in the Indian Ocean. Ug4 colonised Cucurbita pepo, Cucurbita sativus, Leonotis nepetifolia and Pavonia urens, while Ug7 colonised Commelina benghalensis, Gossypium hirsutum and Phaseolus vulgaris. Ug6, the B-biotype-like genotype colonised Abelmoschus esculentus and C. benghalensis only. None of Ug4-Ug7 genotypes was found associated with, or colonising, cassava or sweetpotato plants. In addition to colonising sweetpotato, the Ug8 genotypes colonised Lycopersicon esculentum and L. nepetifolia. Ug6 and Ug7, both members of the B biotype/B-like cluster, induced silverleaf symptoms on Cucurbita sp. The discovery of five previously identified B. tabaci genotype clusters, Ug3-Ug7, in Uganda, among which are some of the world's most economically important biotypes, namely B and Q, is particularly significant in the spread of gemini-viruses with devastating effects to crop production in Africa. © 2005 The Authors.
• Berry, S. D., Fondong, V. N., Rey, C., Rogan, D., Fauquet, C. M., & Brown, J. K. (2004). Molecular evidence for five distinct Bemisia tabaci (Homoptera: Aleyrodidae) geographic haplotypes associated with cassava plants in Sub-Saharan Africa. Annals of the Entomological Society of America, 97(4), 852-859.
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  Abstract: The Bemisia tabaci (Gennadius) complex contains the only known whitefly vector of plant-infecting begomoviruses, which are the causal agents of mosaic diseases of cassava in Africa and India. Widespread phenotypic variability, together with the absence of definitive morphological taxonomic characters for this whitefly complex, has confounded both the systematics and the study of its virus vector biology. Substantial genetic variability and phylogeographical relationships have been shown for phenotypic, but morphologically identical, variants of B. tabaci based on the mitochondrial (mt) cytochrome oxidase I (COI) sequence, leading to the suggestion that they represent a species complex. Here, phylogenetic relationships were explored, using the mtCOI sequence (780 bp) as a molecular marker, for B. tabaci collected from cassava plants in southern and western Africa, including Cameroon, Zambia, Mozambique, Zimbabwe, Swaziland, and South Africa. Maximum likelihood analyses of mtCOI sequences revealed that most B. tabaci examined were placed into one of three subgroups within the major sub-Saharan African clade, which also contains previously reported populations indigenous to Malawi and Uganda, and collectively shared on overall nucleotide (nt) identity at 88.9 -99.7%. Two other reference populations, the monophagous Benin haplotype from Asystasia spp. and a B. tabaci from cassava in the Ivory Coast (IC),were the most divergent outliers of the sub-Saharan clade, each representing the only member of their respective clade (I and V), at the present time. Members of the sub-Saharan clade associated with cassava had as their closest relatives haplotypes I and II of the Mediterranean-Northern Africa clade, with which they shared a collective 84.2-92.9% nt identity (not including the IC cassava reference haplotype). In contrast, the sub-Saharan African clade diverged from the Americas and Southeast Asia/ Far East clades at 79.7- 85.1 and 77.5-84.9%, respectively. Within the sub-Sabaran clade, subclade II contained B. tabaci from Zambia, Mozambique, South Africa, and Swaziland at 95-99% identity. The sub-Saharan subcluster III contained haplotypes from southern and western Africa. Counter to the otbwerwise phylogeographical relationships observed for cassava-associated B. tabaci from southern Africa, one and two populations from Cameroon (okra) and Zimbabwe (cassava), respectively, grouped with the major Mediterranean-North Africa clade, together with their closest relative associated with okra from IC, are included here as a reference sequence for the first time, with which they collectively formed a new, third subelade. Thus, phylogenetic analysis of B. tabaci mtCOI haplotypes examined thus far from the African continent has revealed five major cassava-associated haplotypes, which frouped primarily based on extant geography, with the exception of one and two collections from Cameroon and Zimbabwe, respectively. Hypotheses explaining the potential distributions of haplotypes are discussed. © 2004 Entomological Society of America.
• Berry, S. D., Fondong, V. N., Rey, C., Rogan, D., Fauquet, C. M., & Brown, J. K. (2004). Molecular evidence for five distinct Bemisia tabaci (Homoptera: Aleyrodidae) geographic haplotypes associated with cassava plants in Sub-Saharan Africa. Annals of the Entomological Society of America, 97(Issue 4). doi:10.1603/0013-8746(2004)097[0852:meffdb]2.0.co;2
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  The Bemisia tabaci (Gennadius) complex contains the only known whitefly vector of plant-infecting begomoviruses, which are the causal agents of mosaic diseases of cassava in Africa and India. Widespread phenotypic variability, together with the absence of definitive morphological taxonomic characters for this whitefly complex, has confounded both the systematics and the study of its virus vector biology. Substantial genetic variability and phylogeographical relationships have been shown for phenotypic, but morphologically identical, variants of B. tabaci based on the mitochondrial (mt) cytochrome oxidase I (COI) sequence, leading to the suggestion that they represent a species complex. Here, phylogenetic relationships were explored, using the mtCOI sequence (780 bp) as a molecular marker, for B. tabaci collected from cassava plants in southern and western Africa, including Cameroon, Zambia, Mozambique, Zimbabwe, Swaziland, and South Africa. Maximum likelihood analyses of mtCOI sequences revealed that most B. tabaci examined were placed into one of three subgroups within the major sub-Saharan African clade, which also contains previously reported populations indigenous to Malawi and Uganda, and collectively shared on overall nucleotide (nt) identity at 88.9 -99.7%. Two other reference populations, the monophagous Benin haplotype from Asystasia spp. and a B. tabaci from cassava in the Ivory Coast (IC),were the most divergent outliers of the sub-Saharan clade, each representing the only member of their respective clade (I and V), at the present time. Members of the sub-Saharan clade associated with cassava had as their closest relatives haplotypes I and II of the Mediterranean-Northern Africa clade, with which they shared a collective 84.2-92.9% nt identity (not including the IC cassava reference haplotype). In contrast, the sub-Saharan African clade diverged from the Americas and Southeast Asia/ Far East clades at 79.7- 85.1 and 77.5-84.9%, respectively. Within the sub-Sabaran clade, subclade II contained B. tabaci from Zambia, Mozambique, South Africa, and Swaziland at 95-99% identity. The sub-Saharan subcluster III contained haplotypes from southern and western Africa. Counter to the otbwerwise phylogeographical relationships observed for cassava-associated B. tabaci from southern Africa, one and two populations from Cameroon (okra) and Zimbabwe (cassava), respectively, grouped with the major Mediterranean-North Africa clade, together with their closest relative associated with okra from IC, are included here as a reference sequence for the first time, with which they collectively formed a new, third subelade. Thus, phylogenetic analysis of B. tabaci mtCOI haplotypes examined thus far from the African continent has revealed five major cassava-associated haplotypes, which frouped primarily based on extant geography, with the exception of one and two collections from Cameroon and Zimbabwe, respectively. Hypotheses explaining the potential distributions of haplotypes are discussed. © 2004 Entomological Society of America.
• Idris, A. M., & Brown, J. K. (2004). Cotton leaf crumple virus is a distinct Western Hemisphere begomovirus species with complex evolutionary relationships indicative of recombination and reassortment. Phytopathology, 94(10), 1068-1074.
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  PMID: 18943795;Abstract: The bipartite DNA genome of Cotton leaf crumple virus (CLCrV), a whitefly-transmitted begomovirus from the Sonoran Desert, was cloned and completely sequenced. The cloned CLCrV genome was infectious when biolistically delivered to cotton or bean seedlings and progeny virus was whitefly- transmissible. Koch's postulates were completed by the reproduction of characteristic leaf crumple symptoms in cotton seedlings infected with cloned CLCrV DNA, thereby verifying the etiology of leaf crumple disease, which has been known in the southwestern United States since the 1950s. Sequence comparisons confirmed that CLCrV has a genome organization typical of yet sufficiently divergent from all other bipartite begomoviruses to justify recognition as a distinct species. Phylogenetic analyses indicated that CLCrV has a complex evolutionary history probably involving both recombination and reassortment. The relatively low nucleotide sequence identity (77%) of the common region shared by the CLCrV DNA-A and DNA-B components and the distinct phylogenetic relationships of each component are consistent with component reassortment. Sequence analyses indicated that the CLCrV DNA-A component was likely derived by recombination among ancestors of two divergent clades (e.g., the Squash leaf curl virus [SLCV] clade and the Abutilon mosaic virus clade) of Western Hemisphere begomoviruses. The CLCrV DNA-B component also may have originated by recombination among an ancestor of the SLCV clade and another distantly related but unknown Western Hemisphere begomovirus.
• Idris, A. M., & Brown, J. K. (2004). Cotton leaf crumple virus is a distinct Western Hemisphere begomovirus species with complex evolutionary relationships indicative of recombination and reassortment. Phytopathology, 94(Issue 10). doi:10.1094/phyto.2004.94.10.1068
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  The bipartite DNA genome of Cotton leaf crumple virus (CLCrV), a whitefly-transmitted begomovirus from the Sonoran Desert, was cloned and completely sequenced. The cloned CLCrV genome was infectious when biolistically delivered to cotton or bean seedlings and progeny virus was whitefly- transmissible. Koch's postulates were completed by the reproduction of characteristic leaf crumple symptoms in cotton seedlings infected with cloned CLCrV DNA, thereby verifying the etiology of leaf crumple disease, which has been known in the southwestern United States since the 1950s. Sequence comparisons confirmed that CLCrV has a genome organization typical of yet sufficiently divergent from all other bipartite begomoviruses to justify recognition as a distinct species. Phylogenetic analyses indicated that CLCrV has a complex evolutionary history probably involving both recombination and reassortment. The relatively low nucleotide sequence identity (77%) of the common region shared by the CLCrV DNA-A and DNA-B components and the distinct phylogenetic relationships of each component are consistent with component reassortment. Sequence analyses indicated that the CLCrV DNA-A component was likely derived by recombination among ancestors of two divergent clades (e.g., the Squash leaf curl virus [SLCV] clade and the Abutilon mosaic virus clade) of Western Hemisphere begomoviruses. The CLCrV DNA-B component also may have originated by recombination among an ancestor of the SLCV clade and another distantly related but unknown Western Hemisphere begomovirus.
• Morin, S., Henderson, S., Fabrick, J. A., Carrière, Y., Dennehy, T. J., Brown, J. K., & Tabashnik, B. E. (2004). DNA-based detection of Bt resistance alleles in pink bollworm. Insect Biochemistry and Molecular Biology, 34(11), 1225-1233.
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  PMID: 15522618;Abstract: Evolution of resistance by pests is the main threat to long-term insect control by transgenic crops that produce Bacillus thuringiensis (Bt) toxins. We previously identified three mutant alleles (r1, r2, r3) of a cadherin gene in pink bollworm (Pectinophora gossypiella) linked with recessive resistance to Bt toxin Cry1Ac and survival on transgenic Bt cotton. Here we describe a polymerase chain reaction (PCR)-based method that detects the mutation in genomic DNA of each of the three resistant alleles. Using primers that distinguish between resistant and susceptible (s) alleles, this method enables identification of 10 genotypes (r1r1, r1r2, r1r3, r2r2, r2r3, r3r3, r1s, r2s, r3s, and ss) at the cadherin locus. For each of the three resistant alleles, the method detected the resistance allele in a single heterozygote (r1s, r2s, or r3s) pooled with DNA from the equivalent of 19 susceptible (ss) individuals. The results suggest that the DNA-based detection method described here could greatly increase the efficiency of monitoring for resistance to Cry1Ac compared to bioassays that detect rare individuals with homozygous resistance. © 2004 Elsevier Ltd. All rights reserved.
• Morin, S., Henderson, S., Fabrick, J. A., Carrière, Y., Dennehy, T. J., Brown, J. K., & Tabashnik, B. E. (2004). DNA-based detection of Bt resistance alleles in pink bollworm. Insect Biochemistry and Molecular Biology, 34(Issue 11). doi:10.1016/j.ibmb.2004.08.003
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  Evolution of resistance by pests is the main threat to long-term insect control by transgenic crops that produce Bacillus thuringiensis (Bt) toxins. We previously identified three mutant alleles (r1, r2, r3) of a cadherin gene in pink bollworm (Pectinophora gossypiella) linked with recessive resistance to Bt toxin Cry1Ac and survival on transgenic Bt cotton. Here we describe a polymerase chain reaction (PCR)-based method that detects the mutation in genomic DNA of each of the three resistant alleles. Using primers that distinguish between resistant and susceptible (s) alleles, this method enables identification of 10 genotypes (r1r1, r1r2, r1r3, r2r2, r2r3, r3r3, r1s, r2s, r3s, and ss) at the cadherin locus. For each of the three resistant alleles, the method detected the resistance allele in a single heterozygote (r1s, r2s, or r3s) pooled with DNA from the equivalent of 19 susceptible (ss) individuals. The results suggest that the DNA-based detection method described here could greatly increase the efficiency of monitoring for resistance to Cry1Ac compared to bioassays that detect rare individuals with homozygous resistance. © 2004 Elsevier Ltd. All rights reserved.
• Sseruwagi, P., Rey, M. E., Brown, J. K., & Legg, J. P. (2004). The cassava mosaic geminiviruses occurring in Uganda following the 1990s epidemic of severe cassava mosaic disease. Annals of Applied Biology, 145(1), 113-121.
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  Abstract: The cassava mosaic geminiviruses (CMGs) isolated from cassava plants expressing mild and severe symptoms of cassava mosaic disease (CMD) in 2002 in Uganda were investigated using the polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) molecular techniques and DNA sequencing. Two previously described cassava mosaic geminiviruses: African cassava mosaic virus (ACMV) and East African cassava mosaic virus - Uganda variant (EACMV-UG2) were detected in Uganda. The RFLP technique distinguished two polymorphic variants of ACMV (ACMV-UG1 and ACMV-UG2) and three of EACMV-UG2 (EACMV-UG2[1], EACMV-UG2[2] and EACMV-UG2[3]). ACMV-UG1 produced the fragments predicted for the published sequences of ACMV-[KE]/UGMld/ UGSvr, while ACMV-UG2, which produced the RFLP fragments predicted for the West African ACMV isolates ACMV-[NG], ACMV-[CM], ACMV-[CM/DO2] and ACMV-[CI], was shown to be ACMV-UGMld/UGSvr after DNA sequencing. EACMV-UG2[1] produced the RFLP fragments predicted for the published sequences of EACMV-UG2/UG2Mld/UG2Svr. However, both EACMV-UG2[2] and EACMV-UG2[3], which produced East African cassava mosaic virus-[Tanzania]-like polymorphic fragments with RFLP analysis, were confirmed to be isolates of EACMV-UG2 after DNA sequencing. Thus, this study emphasises the importance of DNA sequence analysis for the identification of CMG isolates. EACMV-UG2 was the predominant virus and occurred in all the surveyed regions. It was detected in 73% of the severely and 53% of the mildly diseased plants, while ACMV was less widespread and occurred most frequently in the mildly diseased plants (in 27% of these plants). Mixed infections of ACMV and EACMV-UG2 were detected in only 18% of the field samples. Unlike previously reported results the mixed infection occurred almost equally in plants exhibiting mild or severe disease symptoms (21% and 16%, respectively). The increasing frequency of mild forms of EACMV-UG2 together with the continued occurrence of severe forms in the field warrants further studies of virus-virus and virus-host interactions. © 2004 Association of Applied Biologists.
• Sseruwagi, P., Rey, M. E., Brown, J. K., & Legg, J. P. (2004). The cassava mosaic geminiviruses occurring in Uganda following the 1990s epidemic of severe cassava mosaic disease. Annals of Applied Biology, 145(Issue 1). doi:10.1111/j.1744-7348.2004.tb00366.x
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  The cassava mosaic geminiviruses (CMGs) isolated from cassava plants expressing mild and severe symptoms of cassava mosaic disease (CMD) in 2002 in Uganda were investigated using the polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) molecular techniques and DNA sequencing. Two previously described cassava mosaic geminiviruses: African cassava mosaic virus (ACMV) and East African cassava mosaic virus - Uganda variant (EACMV-UG2) were detected in Uganda. The RFLP technique distinguished two polymorphic variants of ACMV (ACMV-UG1 and ACMV-UG2) and three of EACMV-UG2 (EACMV-UG2[1], EACMV-UG2[2] and EACMV-UG2[3]). ACMV-UG1 produced the fragments predicted for the published sequences of ACMV-[KE]/UGMld/ UGSvr, while ACMV-UG2, which produced the RFLP fragments predicted for the West African ACMV isolates ACMV-[NG], ACMV-[CM], ACMV-[CM/DO2] and ACMV-[CI], was shown to be ACMV-UGMld/UGSvr after DNA sequencing. EACMV-UG2[1] produced the RFLP fragments predicted for the published sequences of EACMV-UG2/UG2Mld/UG2Svr. However, both EACMV-UG2[2] and EACMV-UG2[3], which produced East African cassava mosaic virus-[Tanzania]-like polymorphic fragments with RFLP analysis, were confirmed to be isolates of EACMV-UG2 after DNA sequencing. Thus, this study emphasises the importance of DNA sequence analysis for the identification of CMG isolates. EACMV-UG2 was the predominant virus and occurred in all the surveyed regions. It was detected in 73% of the severely and 53% of the mildly diseased plants, while ACMV was less widespread and occurred most frequently in the mildly diseased plants (in 27% of these plants). Mixed infections of ACMV and EACMV-UG2 were detected in only 18% of the field samples. Unlike previously reported results the mixed infection occurred almost equally in plants exhibiting mild or severe disease symptoms (21% and 16%, respectively). The increasing frequency of mild forms of EACMV-UG2 together with the continued occurrence of severe forms in the field warrants further studies of virus-virus and virus-host interactions. © 2004 Association of Applied Biologists.
• Briddon, R. W., Bull, S. E., Amin, I., Idris, A. M., Mansoor, S., Bedford, I. D., Dhawan, P., Rishi, N., Siwatch, S. S., Abdel-Salam, A. M., Brown, J. K., Zafar, Y., & Markham, P. G. (2003). Diversity of DNA β, a satellite molecule associated with some monopartite begomoviruses. Virology, 312(1), 106-121.
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  PMID: 12890625;Abstract: DNA β molecules are symptom-modulating, single-stranded DNA satellites associated with monopartite begomoviruses (family Geminiviridae). Such molecules have thus far been shown to be associated with Ageratum yellow vein virus from Singapore and Cotton leaf curl Multan virus from Pakistan. Here, 26 additional DNA β molecules, associated with diverse plant species obtained from different geographical locations, were cloned and sequenced. These molecules were shown to be widespread in the Old World, where monopartite begomoviruses are known to occur. Analysis of the sequences revealed a highly conserved organization for DNA β molecules consisting of a single conserved open reading frame, an adenine-rich region, and a region of high sequence conservation [the satellite conserved region (SCR)]. The SCR contains a potential hairpin structure with the loop sequence TAA/GTATTAC; similar to the origins of replication of geminiviruses and nanoviruses. Two major groups of DNA β satellites were resolved by phylogenetic analyses. One group originated from hosts within the Malvaceae and the second from a more diverse group of plants within the Solanaceae and Compositae. Within the two clusters, DNA β molecules showed relatedness based both on host and geographic origin. These findings strongly support coadaptation of DNA β molecules with their respective helper begomoviruses. © 2003 Elsevier Science (USA). All rights reserved.
• Briddon, R. W., Bull, S. E., Amin, I., Idris, A. M., Mansoor, S., Bedford, I. D., Dhawan, P., Rishi, N., Siwatch, S. S., Abdel-Salam, A. M., Brown, J. K., Zafar, Y., & Markham, P. G. (2003). Diversity of DNA β, a satellite molecule associated with some monopartite begomoviruses. Virology, 312(Issue 1). doi:10.1016/s0042-6822(03)00200-9
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  DNA β molecules are symptom-modulating, single-stranded DNA satellites associated with monopartite begomoviruses (family Geminiviridae). Such molecules have thus far been shown to be associated with Ageratum yellow vein virus from Singapore and Cotton leaf curl Multan virus from Pakistan. Here, 26 additional DNA β molecules, associated with diverse plant species obtained from different geographical locations, were cloned and sequenced. These molecules were shown to be widespread in the Old World, where monopartite begomoviruses are known to occur. Analysis of the sequences revealed a highly conserved organization for DNA β molecules consisting of a single conserved open reading frame, an adenine-rich region, and a region of high sequence conservation [the satellite conserved region (SCR)]. The SCR contains a potential hairpin structure with the loop sequence TAA/GTATTAC; similar to the origins of replication of geminiviruses and nanoviruses. Two major groups of DNA β satellites were resolved by phylogenetic analyses. One group originated from hosts within the Malvaceae and the second from a more diverse group of plants within the Solanaceae and Compositae. Within the two clusters, DNA β molecules showed relatedness based both on host and geographic origin. These findings strongly support coadaptation of DNA β molecules with their respective helper begomoviruses. © 2003 Elsevier Science (USA). All rights reserved.
• Fauquet, C. M., Bisaro, D. M., Briddon, R. W., Brown, J. K., Harrison, B. D., Rybicki, E. P., Stenger, D. C., & Stanley, J. (2003). Revision of taxonomic criteria for species demarcation in the family Geminiviridae, and an updated list of begomovirus species. Archives of Virology, 148(2), 405-421.
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  PMID: 12557003;
• Fauquet, C. M., Bisaro, D. M., Briddon, R. W., Brown, J. K., Harrison, B. D., Rybicki, E. P., Stenger, D. C., & Stanley, J. (2003). Revision of taxonomic criteria for species demarcation in the family Geminiviridae, and an updated list of begomovirus species. Archives of Virology, 148(Issue 2). doi:10.1007/s00705-002-0957-5
• Idris, A. M., Hiebert, E., Bird, J., & Brown, J. K. (2003). Two newly described begomoviruses of Macroptilium lathyroides and common bean. Phytopathology, 93(7), 774-783.
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  PMID: 18943157;Abstract: Macroptilium lathyroides, a perennial weed in the Caribbean region and Central America, is a host of Macroptilium yellow mosaic Florida virus (MaYMFV) and Macroptilium mosaic Puerto Rico virus (MaMPRV). The genomes of MaYMFV and MaMPRV were cloned from M. lathyroides and/or field-infected bean and the DNA sequences were determined. Cloned A and B components for both viruses were infectious when inoculated to M. lathyroides and common bean. Comparison of the DNA sequences for cloned A and B components with well-studied begomovims indicated that MaMPRV (bean and M. lathyroides) and MaYMFV (M. lathyroides) are unique, previously undescribed begomo-viruses from the Western Hemisphere. Phylogenetic analysis of viral A components indicated that the closest relative of MaYMFV are members of the Bean golden yellow mosaic virus (BGYMV) group, at 76 to 78% nucleotide identity, whereas the closest relative for the A component of MaMPRV was Rhynchosia golden mosaic virus at 78% nucleotide identity. In contrast, BGYMV is the closest relative for the B component of both MaYMFV and MaMPRV, with which they share ≈68.0 and ≈72% identity, respectively. The incongruent taxonomic placement for the bipartite components for MaMPRV indicates that they did not evolve entirely along a common path. MaYMFV and MaMPRV caused distinctive symptoms in bean and M. lathyroides and were transmissible by the whitefly vector and by grafting; however, only MaYMFV was mechanically transmissible. The experimental host range for the two viruses was similar and included species within the families Fabaceae and Malvaceae, but only MaYMFV infected Malva parviflora and soybean. These results collectively indicate that MaMPRV and MaYMFV are new, previously undescribed species of the BGYMV group, a clade previously known to contain only strains and isolates of BGYMV from the Caribbean region that infect Phaseohts spp. Both MaYMFV and MaMPRV may pose an economic threat to bean production in the region.
• Idris, A. M., Hiebert, E., Bird, J., & Brown, J. K. (2003). Two newly described begomoviruses of Macroptilium lathyroides and common bean. Phytopathology, 93(Issue 7). doi:10.1094/phyto.2003.93.7.774
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  Macroptilium lathyroides, a perennial weed in the Caribbean region and Central America, is a host of Macroptilium yellow mosaic Florida virus (MaYMFV) and Macroptilium mosaic Puerto Rico virus (MaMPRV). The genomes of MaYMFV and MaMPRV were cloned from M. lathyroides and/or field-infected bean and the DNA sequences were determined. Cloned A and B components for both viruses were infectious when inoculated to M. lathyroides and common bean. Comparison of the DNA sequences for cloned A and B components with well-studied begomovims indicated that MaMPRV (bean and M. lathyroides) and MaYMFV (M. lathyroides) are unique, previously undescribed begomo-viruses from the Western Hemisphere. Phylogenetic analysis of viral A components indicated that the closest relative of MaYMFV are members of the Bean golden yellow mosaic virus (BGYMV) group, at 76 to 78% nucleotide identity, whereas the closest relative for the A component of MaMPRV was Rhynchosia golden mosaic virus at 78% nucleotide identity. In contrast, BGYMV is the closest relative for the B component of both MaYMFV and MaMPRV, with which they share ≈68.0 and ≈72% identity, respectively. The incongruent taxonomic placement for the bipartite components for MaMPRV indicates that they did not evolve entirely along a common path. MaYMFV and MaMPRV caused distinctive symptoms in bean and M. lathyroides and were transmissible by the whitefly vector and by grafting; however, only MaYMFV was mechanically transmissible. The experimental host range for the two viruses was similar and included species within the families Fabaceae and Malvaceae, but only MaYMFV infected Malva parviflora and soybean. These results collectively indicate that MaMPRV and MaYMFV are new, previously undescribed species of the BGYMV group, a clade previously known to contain only strains and isolates of BGYMV from the Caribbean region that infect Phaseohts spp. Both MaYMFV and MaMPRV may pose an economic threat to bean production in the region.
• Morin, S., Biggs, R. W., Sisterson, M. S., Shriver, L., Ellers-Kirk, C., Higginson, D., Holley, D., Gahan, L. J., Heckel, D. G., Carrière, Y., Dennehy, T. J., Brown, J. K., & Tabashnik, B. E. (2003). Three cadherin alleles associated with resistance to Bacillus thuringiensis in pink bollworm. Proceedings of the National Academy of Sciences of the United States of America, 100(9), 5004-5009.
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  PMID: 12695565;PMCID: PMC154288;Abstract: Evolution of resistance by pests is the main threat to long-term insect control by transgenic crops that produce Bacillus thuringiensis (Bt) toxins. Because inheritance of resistance to the Bt toxins in transgenic crops is typically recessive, DNA-based screening for resistance alleles in heterozygotes is potentially much more efficient than detection of resistant homozygotes with bioassays. Such screening, however, requires knowledge of the resistance alleles in field populations of pests that are associated with survival on Bt crops. Here we report that field populations of pink bollworm (Pectinophora gossypiella), a major cotton pest, harbored three mutant alleles of a cadherin-encoding gene linked with resistance to Bt toxin Cry1Ac and survival on transgenic Bt cotton. Each of the three resistance alleles has a deletion expected to eliminate at least eight amino acids upstream of the putative toxin-binding region of the cadherin protein. Larvae with two resistance alleles in any combination were resistant, whereas those with one or none were susceptible to Cry1Ac. Together with previous evidence, the results reported here identify the cadherin gene as a leading target for DNA-based screening of resistance to Bt crops in lepidopteran pests.
• Morin, S., Biggs, R. W., Sisterson, M. S., Shriver, L., Ellers-Kirk, C., Higginson, D., Holley, D., Gahan, L. J., Heckel, D. G., Carrière, Y., Dennehy, T. J., Brown, J. K., & Tabashnik, B. E. (2003). Three cadherin alleles associated with resistance to Bacillus thuringiensis in pink bollworm. Proceedings of the National Academy of Sciences of the United States of America, 100(Issue 9). doi:10.1073/pnas.0831036100
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  Evolution of resistance by pests is the main threat to long-term insect control by transgenic crops that produce Bacillus thuringiensis (Bt) toxins. Because inheritance of resistance to the Bt toxins in transgenic crops is typically recessive, DNA-based screening for resistance alleles in heterozygotes is potentially much more efficient than detection of resistant homozygotes with bioassays. Such screening, however, requires knowledge of the resistance alleles in field populations of pests that are associated with survival on Bt crops. Here we report that field populations of pink bollworm (Pectinophora gossypiella), a major cotton pest, harbored three mutant alleles of a cadherin-encoding gene linked with resistance to Bt toxin Cry1Ac and survival on transgenic Bt cotton. Each of the three resistance alleles has a deletion expected to eliminate at least eight amino acids upstream of the putative toxin-binding region of the cadherin protein. Larvae with two resistance alleles in any combination were resistant, whereas those with one or none were susceptible to Cry1Ac. Together with previous evidence, the results reported here identify the cadherin gene as a leading target for DNA-based screening of resistance to Bt crops in lepidopteran pests.
• Rosell, R. C., Davidson, E. W., Jancovich, J. K., Hendrix, D. L., & Brown, J. K. (2003). Size limitations in the filter chamber and digestive tract of nymphal and adult Bemisia tabaci whiteflies (Hemiptera: Aleyrodidae). Annals of the Entomological Society of America, 96(4), 544-552.
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  Abstract: The molecular size limitations of the digestive system, including the filter chamber of immature and adult Bemisia tabaci (Gennadius) B biotype (= B. argentifolii), were studied by tracking the movement of fluorescent-labeled molecules and microspheres ingested by whiteflies. Soluble fluorescent molecules and labeled dextrans, ranging from 389 to 2,000,000 Da, were observed throughout the digestive tract of immatures 10-30 min after feeding was initiated. After removal of labeled molecules from the diet, fluorochromes were cleared from digestive system of immatures within 2 h. Fluorescent-labeled 0.1 - and 0.2-μm microspheres were ingested by larvae and saturated the digestive system within 2 h after initiation of feeding. Large, 0.5-μm spheres were not observed in the digestive tract of immatures, probably because singly or as aggregates, they were too large to enter the stylet food canal. The smallest spheres examined, 0.02 μm, were not detectable in the digestive tract of immatures. Observations for whitefly adults were identical to those for larvae, with two exceptions. In adults, soluble fluorochromes were detectable1 h after feeding commenced, and 0.02-μm spheres were observed primarily in the esophagus, filter chamber, anterior midgut, and hindgut, but not in the posterior portions of the midgut. We hypothesize that most of the 0.02-μm spheres ingested by adult whiteflies were shunted directly to the hindgut by way of the filter chamber, effectively bypassing the midgut. This is, therefore, a feasible route for virions of the plant pathogenic genus Begomovirus, which are of similar size to the small microspheres and are transmitted in a circulative manner by B. tabaci.
• Rosell, R. C., Davidson, E. W., Jancovich, J. K., Hendrix, D. L., & Brown, J. K. (2003). Size limitations in the filter chamber and digestive tract of nymphal and adult Bemisia tabaci whiteflies (Hemiptera: Aleyrodidae). Annals of the Entomological Society of America, 96(Issue 4). doi:10.1603/0013-8746(2003)096[0544:slitfc]2.0.co;2
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  The molecular size limitations of the digestive system, including the filter chamber of immature and adult Bemisia tabaci (Gennadius) B biotype (= B. argentifolii), were studied by tracking the movement of fluorescent-labeled molecules and microspheres ingested by whiteflies. Soluble fluorescent molecules and labeled dextrans, ranging from 389 to 2,000,000 Da, were observed throughout the digestive tract of immatures 10-30 min after feeding was initiated. After removal of labeled molecules from the diet, fluorochromes were cleared from digestive system of immatures within 2 h. Fluorescent-labeled 0.1 - and 0.2-μm microspheres were ingested by larvae and saturated the digestive system within 2 h after initiation of feeding. Large, 0.5-μm spheres were not observed in the digestive tract of immatures, probably because singly or as aggregates, they were too large to enter the stylet food canal. The smallest spheres examined, 0.02 μm, were not detectable in the digestive tract of immatures. Observations for whitefly adults were identical to those for larvae, with two exceptions. In adults, soluble fluorochromes were detectable1 h after feeding commenced, and 0.02-μm spheres were observed primarily in the esophagus, filter chamber, anterior midgut, and hindgut, but not in the posterior portions of the midgut. We hypothesize that most of the 0.02-μm spheres ingested by adult whiteflies were shunted directly to the hindgut by way of the filter chamber, effectively bypassing the midgut. This is, therefore, a feasible route for virions of the plant pathogenic genus Begomovirus, which are of similar size to the small microspheres and are transmitted in a circulative manner by B. tabaci.
• Viscarret, M. M., Torres-Jerez, I., Agostini De Manero, E., López, S. N., Botto, E. E., & Brown, J. K. (2003). Mitochondrial DNA evidence for a distinct New World group of Bemisia tabaci (Gennadius) (Hemiptera: Alyerodidae) indigenous to Argentina and Bolivia, and presence of the Old World B biotype in Argentina. Annals of the Entomological Society of America, 96(Issue 1). doi:10.1603/0013-8746(2003)096[0065:mdefad]2.0.co;2
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  A study was undertaken to establish the diversity within the Bemisia tabaci (Gennadius) species complex in Argentina using the mitochondria cytochrome oxidase I gene (mt COI) as a molecular marker. For one haplotype, common to cotton in the Santiago Province, biotic characters were evaluated, and included host range and life history traits: fecundity, generation time, intrinsic rate of increase, longevity, and rate of reproduction. To investigate genetic diversity, B. tabaci were collected from representative geographical locations and host plants in six provinces of Argentina. Also, B. tabaci found colonizing tomato plants in nearby Bolivia, which exhibited viruslike symptoms, were included in the study. We report, for the first time, the presence of the introduced 'B' biotype in Argentina, and present evidence for indigenous or 'local' B. tabaci haplotypes in both Argentina (ARG) and Bolivia (BOL), which collectively formed a distinctive, South American phylogeographic grouping of New World B. tabaci. Two closely related ARG haplotypes, ARG2/3 from Salta and Tucamán, and ARGI from Santiago, shared 98.7% identity, whereas the Bolivian haplotype (BOL), their closet relative, shared 99.4% and 99.9% identity with ARGI and ARG2/3, respectively. Mt COI sequences for collections identified as the 'B' biotype from Argentina (ARG4/5) shared 99.5-100% nt identity with the five 'B' biotype reference sequences and colonies established for ARG4 and ARG5 were capable of inducing silvering in Cucurbita spp., confirming their identity as the B biotype. The closest relatives to the ARG/BOL haplotypes were members of the North/Central American clade of B. tabaci with which they shared 4.6 to 8.6% identity, indicating that the ARG and BOL B. tabaci are of New World origin. The latter range of divergence is similar to that estimated for the Old World B biotype and its closest relatives from the Mediterranean region, at 5.4 to 6.4%. Divergence estimates for Old World X Old World and New World X Old World phylogeographical clades were 14.6 to 16.2% and 14.4 to 17.4%, respectively, indicating that haplotypes in both eastern and western hemispheres exhibit substantial diversity from one another. Despite the somewhat more moderate interclade divergence for New World compared with Old World clades, the South American B. tabaci formed a distinctive New World clade, suggesting a common ancestry with other previously studied New World taxa, from which they are separated by geographical barriers. Life history traits for the cotton-associated B. tabaci haplotype (ARGI) were most similar to those previously reported for the polyphagous A biotype, AZA, from Arizona, and differed substantially with respect to the B biotype.
• Viscarret, M. M., Torres-Jerez, I., Agostini, E., López, S., Botto, E. E., & Brown, J. K. (2003). Mitochondrial DNA evidence for a distinct New World group of Bemisia tabaci (Gennadius) (Hemiptera: Alyerodidae) indigenous to Argentina and Bolivia, and presence of the Old World B biotype in Argentina. Annals of the Entomological Society of America, 96(1), 65-72.
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  Abstract: A study was undertaken to establish the diversity within the Bemisia tabaci (Gennadius) species complex in Argentina using the mitochondria cytochrome oxidase I gene (mt COI) as a molecular marker. For one haplotype, common to cotton in the Santiago Province, biotic characters were evaluated, and included host range and life history traits: fecundity, generation time, intrinsic rate of increase, longevity, and rate of reproduction. To investigate genetic diversity, B. tabaci were collected from representative geographical locations and host plants in six provinces of Argentina. Also, B. tabaci found colonizing tomato plants in nearby Bolivia, which exhibited viruslike symptoms, were included in the study. We report, for the first time, the presence of the introduced 'B' biotype in Argentina, and present evidence for indigenous or 'local' B. tabaci haplotypes in both Argentina (ARG) and Bolivia (BOL), which collectively formed a distinctive, South American phylogeographic grouping of New World B. tabaci. Two closely related ARG haplotypes, ARG2/3 from Salta and Tucamán, and ARGI from Santiago, shared 98.7% identity, whereas the Bolivian haplotype (BOL), their closet relative, shared 99.4% and 99.9% identity with ARGI and ARG2/3, respectively. Mt COI sequences for collections identified as the 'B' biotype from Argentina (ARG4/5) shared 99.5-100% nt identity with the five 'B' biotype reference sequences and colonies established for ARG4 and ARG5 were capable of inducing silvering in Cucurbita spp., confirming their identity as the B biotype. The closest relatives to the ARG/BOL haplotypes were members of the North/Central American clade of B. tabaci with which they shared 4.6 to 8.6% identity, indicating that the ARG and BOL B. tabaci are of New World origin. The latter range of divergence is similar to that estimated for the Old World B biotype and its closest relatives from the Mediterranean region, at 5.4 to 6.4%. Divergence estimates for Old World X Old World and New World X Old World phylogeographical clades were 14.6 to 16.2% and 14.4 to 17.4%, respectively, indicating that haplotypes in both eastern and western hemispheres exhibit substantial diversity from one another. Despite the somewhat more moderate interclade divergence for New World compared with Old World clades, the South American B. tabaci formed a distinctive New World clade, suggesting a common ancestry with other previously studied New World taxa, from which they are separated by geographical barriers. Life history traits for the cotton-associated B. tabaci haplotype (ARGI) were most similar to those previously reported for the polyphagous A biotype, AZA, from Arizona, and differed substantially with respect to the B biotype.
• Brown, J. K., & Czosnek, H. (2002). Whitefly transmission of plant viruses. Advances in Botanical Research, 36, 65-76,IN1-IN2,77-100.
• Brown, J. K., Idris, A. M., Alteri, C., & Stenger, D. C. (2002). Emergence of a new Cucurbit-infecting begomovirus species capable of forming viable reassortants with related viruses in the Squash leaf curl virus cluster. Phytopathology, 92(7), 734-742.
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  PMID: 18943269;Abstract: Cucurbit leaf curl virus (CuLCV), a whitefly-transmitted geminivirus previously partially characterized from the southwestern United States and northern Mexico, was identified as a distinct bipartite begomovirus species. This virus has near sequence identity with the previously partially characterized Cucurbit leaf crumple virus from California. Experimental and natural host range studies indicated that CuLCV has a relatively broad host range within the family Cucurbitaceae and also infects bean and tobacco. The genome of an Arizona isolate, designated CuLCV-AZ, was cloned and completely sequenced. Cloned CuLCV-AZ DNA A and B components were infectious by biolistic inoculation to pumpkin and progeny virus was transmissible by the whitefly vector, Bemisia tabaci, thereby completing Koch's postulates. CuLCV-AZ DNA A shared highest nucleotide sequence identity with Squash leaf curl virus-R (SLCV-R), SLCV-E, and Bean calico mosaic virus (BCaMV) at 84, 83, and 80%, respectively. The CuLCV DNA B component shared highest nucleotide sequence identity with BCaMV, SLCV-R, and SLCV-E at 71, 70, and 68%, respectively. The cis-acting begomovirus replication specificity element, GGTGTCCTGGTG, in the CuLCV-AZ origin of replication is identical to that of SLCV-R, SLCV-E, and BCaMV, suggesting that reassortants among components of CuLCV-AZ and these begomoviruses may be possible. Reassortment experiments in pumpkin demonstrated that both reassortants of CuLCV-AZ and SLCV-E A and B components were viable. However, for CuLCV-AZ and SLCV-R, only one reassortant (SLCV-R DNA A/CuLCV-AZ DNA B) was viable on pumpkin, even though the cognate component pairs of both viruses infect pumpkin. These results demonstrate that reassortment among sympatric begomovirus species infecting cucurbits are possible, and that, if generated in nature, could result in begomoviruses bearing distinct biological properties.
• Brown, J. K., Idris, A. M., Alteri, C., & Stenger, D. C. (2002). Emergence of a new Cucurbit-infecting begomovirus species capable of forming viable reassortants with related viruses in the Squash leaf curl virus cluster. Phytopathology, 92(Issue 7). doi:10.1094/phyto.2002.92.7.734
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  Cucurbit leaf curl virus (CuLCV), a whitefly-transmitted geminivirus previously partially characterized from the southwestern United States and northern Mexico, was identified as a distinct bipartite begomovirus species. This virus has near sequence identity with the previously partially characterized Cucurbit leaf crumple virus from California. Experimental and natural host range studies indicated that CuLCV has a relatively broad host range within the family Cucurbitaceae and also infects bean and tobacco. The genome of an Arizona isolate, designated CuLCV-AZ, was cloned and completely sequenced. Cloned CuLCV-AZ DNA A and B components were infectious by biolistic inoculation to pumpkin and progeny virus was transmissible by the whitefly vector, Bemisia tabaci, thereby completing Koch's postulates. CuLCV-AZ DNA A shared highest nucleotide sequence identity with Squash leaf curl virus-R (SLCV-R), SLCV-E, and Bean calico mosaic virus (BCaMV) at 84, 83, and 80%, respectively. The CuLCV DNA B component shared highest nucleotide sequence identity with BCaMV, SLCV-R, and SLCV-E at 71, 70, and 68%, respectively. The cis-acting begomovirus replication specificity element, GGTGTCCTGGTG, in the CuLCV-AZ origin of replication is identical to that of SLCV-R, SLCV-E, and BCaMV, suggesting that reassortants among components of CuLCV-AZ and these begomoviruses may be possible. Reassortment experiments in pumpkin demonstrated that both reassortants of CuLCV-AZ and SLCV-E A and B components were viable. However, for CuLCV-AZ and SLCV-R, only one reassortant (SLCV-R DNA A/CuLCV-AZ DNA B) was viable on pumpkin, even though the cognate component pairs of both viruses infect pumpkin. These results demonstrate that reassortment among sympatric begomovirus species infecting cucurbits are possible, and that, if generated in nature, could result in begomoviruses bearing distinct biological properties.
• Brown, S., McLaughlin, W., Jerez, I. T., & Brown, J. K. (2002). Identification and distribution of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) haplotypes in Jamaica. Tropical Agriculture, 79(3), 140-149.
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  Abstract: Collections of Jamaican whiteflies were identified using morphological characters. Those identified as Bemisia tabaci (Gennadius) were further identified to esterase type using diagnostic general esterase patterns using native polyacrylamide gel electrophoresis (PAGE). Over 216 B. tabaci adults from 22 Jamaican collections were identical to the B type esterase banding patterns identified first for the B biotype from Arizona, U.S.A. Of the plant species sampled in Jamaica, 86% were hosts of the B biotype of B. tabaci. Non-B esterase patterns were identified for two B. tabaci colonizing cassava and milkweed, respectively. Maximum likelihood and parsimony analyses of the mitochondrial (mt) 16S ribosomal ribonucleic acid (rRNA) sequences for Jamaican B. tabaci and reference sequences for well-studied B. tabaci haplotypes indicated that the non-B B. tabaci from Jamaica were of New World origin, whereas individuals identified as the B biotype were indistinguishable from those for other B biotype collections, worldwide. Bemisia tabaci collected from cassava in Jamaica was most closely related to the monophagous Jatropha biotype described in Puerto Rico, U.S.A., at 98.2% nucleotide identity. The collection from milkweed shared 98.4-99.6% nucleotide identity with several polyphagous haplotypes in the Americas and Caribbean region. The mt 16S rRNA sequence for the B biotype from tomato and muskmelon in Jamaica shared 99.1-99.3% nucleotide identity with the B biotype reference from Arizona. The presence of two New World haplotypes of B. tabaci in Jamaica are being reported for the first time, which may be analogous to the Jatropha and Sida biotypes (races), respectively, previously known only from Puerto Rico, and confirm that the exotic B biotype of B. tabaci is widespread in Jamaica.
• Brown, S., McLaughlin, W., Jerez, I. T., & Brown, J. K. (2002). Identification and distribution of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) haplotypes in Jamaica. Tropical Agriculture, 79(Issue 3).
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  Collections of Jamaican whiteflies were identified using morphological characters. Those identified as Bemisia tabaci (Gennadius) were further identified to esterase type using diagnostic general esterase patterns using native polyacrylamide gel electrophoresis (PAGE). Over 216 B. tabaci adults from 22 Jamaican collections were identical to the B type esterase banding patterns identified first for the B biotype from Arizona, U.S.A. Of the plant species sampled in Jamaica, 86% were hosts of the B biotype of B. tabaci. Non-B esterase patterns were identified for two B. tabaci colonizing cassava and milkweed, respectively. Maximum likelihood and parsimony analyses of the mitochondrial (mt) 16S ribosomal ribonucleic acid (rRNA) sequences for Jamaican B. tabaci and reference sequences for well-studied B. tabaci haplotypes indicated that the non-B B. tabaci from Jamaica were of New World origin, whereas individuals identified as the B biotype were indistinguishable from those for other B biotype collections, worldwide. Bemisia tabaci collected from cassava in Jamaica was most closely related to the monophagous Jatropha biotype described in Puerto Rico, U.S.A., at 98.2% nucleotide identity. The collection from milkweed shared 98.4-99.6% nucleotide identity with several polyphagous haplotypes in the Americas and Caribbean region. The mt 16S rRNA sequence for the B biotype from tomato and muskmelon in Jamaica shared 99.1-99.3% nucleotide identity with the B biotype reference from Arizona. The presence of two New World haplotypes of B. tabaci in Jamaica are being reported for the first time, which may be analogous to the Jatropha and Sida biotypes (races), respectively, previously known only from Puerto Rico, and confirm that the exotic B biotype of B. tabaci is widespread in Jamaica.
• Idris, A. M. (2002). Molecular analysis of Cotton leaf curl virus-Sudan reveals an evolutionary history of recombination. Virus Genes, 24(3).
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  Monopartite begomoviral DNAs (2761 bp) were cloned and sequenced from field cotton, okra, and Sida alba, from Gezira, and field okra from Shambat. Comparison of the four apparent full-length begomoviral DNAs revealed 99.3-99.5% shared nucleotide (nt) identity, indicating that they are the same viral species, hereafter, referred to as Cotton leaf curl virus-Sudan (CLCuV-SD). Host range studies revealed that the field okra isolate of CLCuV-SD was whitefly-transmissible from okra to okra, M. parviflora, and hollyhock, but not to cotton. In contrast, the cotton isolate of CLCuV-SD infected cotton and hollyhock, but not okra. The genome of CLCuV-SD encodes six open reading frames (ORFs), and was most closely related to other monopartite begomoviruses of the Eastern Hemisphere. CLCuV-SD shared highest nucleotide sequence identity (95.5%) with Okra enation virus (OkEV), but was distantly related (approximately 74% nt sequence identity) to begomoviruses isolated from cotton in Pakistan. While extensive genomic regions of CLCuV-SD and OkEV are highly conserved (approximately 99% nt identity), nt sequence identity of the V1 ORF encoding the coat protein was uncharacteristically low (87.9%), suggesting a history of recombination. An analysis conducted with Sawyer's GENECONV program support the recombination hypothesis, indicating that the V1 ORF and a small segment of the intergenic region of CLCuV-SD and OkEV were derived from other begomoviruses. As a BLAST analysis failed to identify a prospective extant source of either V1 ORF, the parental viruses serving as CP donors remain undiscovered or are extinct.
• Idris, A. M., & Brown, J. K. (2002). Molecular analysis of Cotton leaf curl virus-Sudan reveals an evolutionary history of recombination. Virus Genes, 24(3), 249-256.
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  PMID: 12086146;Abstract: Monopartite begomoviral DNAs (2761 bp) were cloned and sequenced from field cotton, okra, and Sida alba, from Gezira, and field okra from Shambat. Comparison of the four apparent full-length begomoviral DNAs revealed 99.3-99.5% shared nucleotide (nt) identity, indicating that they are the same viral species, hereafter, referred to as Cotton leaf curl virus-Sudan (CLCuV-SD). Host range studies revealed that the field okra isolate of CLCuV-SD was whitefly-transmissible from okra to okra, M. parviflora, and hollyhock, but not to cotton. In contrast, the cotton isolate of CLCuV-SD infected cotton and hollyhock, but not okra. The genome of CLCuV-SD encodes six open reading frames (ORFs), and was most closely related to other monopartite begomoviruses of the Eastern Hemisphere. CLCuV-SD shared highest nucleotide sequence identity (95.5%) with Okra enation virus (OkEV), but was distantly related (∼74% nt sequence identity) to begomoviruses isolated from cotton in Pakistan. While extensive genomic regions of CLCuV-SD and OkEV are highly conserved (∼99% nt identity), nt sequence identity of the V1 ORF encoding the coat protein was uncharacteristically low (87.9%), suggesting a history of recombination. An analysis conducted with Sawyer's GENECONV program support the recombination hypothesis, indicating that the V1 ORF and a small segment of the intergenic region of CLCuV-SD and OkEV were derived from other begomoviruses. As a BLAST analysis failed to identify a prospective extant source of either V1 ORF, the parental viruses serving as CP donors remain undiscovered or are extinct.
• Idris, A. M., & Brown, J. K. (2002). Molecular analysis of Cotton leaf curl virus-Sudan reveals an evolutionary history of recombination. Virus Genes, 24(Issue 3). doi:10.1023/a:1015380600089
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  Monopartite begomoviral DNAs (2761 bp) were cloned and sequenced from field cotton, okra, and Sida alba, from Gezira, and field okra from Shambat. Comparison of the four apparent full-length begomoviral DNAs revealed 99.3-99.5% shared nucleotide (nt) identity, indicating that they are the same viral species, hereafter, referred to as Cotton leaf curl virus-Sudan (CLCuV-SD). Host range studies revealed that the field okra isolate of CLCuV-SD was whitefly-transmissible from okra to okra, M. parviflora, and hollyhock, but not to cotton. In contrast, the cotton isolate of CLCuV-SD infected cotton and hollyhock, but not okra. The genome of CLCuV-SD encodes six open reading frames (ORFs), and was most closely related to other monopartite begomoviruses of the Eastern Hemisphere. CLCuV-SD shared highest nucleotide sequence identity (95.5%) with Okra enation virus (OkEV), but was distantly related (∼74% nt sequence identity) to begomoviruses isolated from cotton in Pakistan. While extensive genomic regions of CLCuV-SD and OkEV are highly conserved (∼99% nt identity), nt sequence identity of the V1 ORF encoding the coat protein was uncharacteristically low (87.9%), suggesting a history of recombination. An analysis conducted with Sawyer's GENECONV program support the recombination hypothesis, indicating that the V1 ORF and a small segment of the intergenic region of CLCuV-SD and OkEV were derived from other begomoviruses. As a BLAST analysis failed to identify a prospective extant source of either V1 ORF, the parental viruses serving as CP donors remain undiscovered or are extinct.
• Legg, J. P., French, R., Rogan, D., Okao-Okuja, G., & Brown, J. K. (2002). A distinct Bemisia tabaci (Gennadius) (Hemiptera: Sternorrhyncha: Aleyrodidae) genotype cluster is associated with the epidemic of severe cassava mosaic virus disease in Uganda. Molecular Ecology, 11(7), 1219-1229.
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  PMID: 12074729;Abstract: During the 1990s, an epidemic of cassava mosaic virus disease caused major losses to cassava production in Uganda. Two factors associated with the epidemic were the occurrence of a novel recombinant begomovirus, EACMV-Ug, and unusually high populations of the whitefly vector, Bemisia tabaci. Here we present molecular evidence for the occurrence of two cassava-colonizing B. tabaci genotype clusters, Ug1 and Ug2, one of which, Ug2, can be consistently associated with the CMD epidemic in Uganda at the time of collection in 1997. By contrast, a second genotype cluster, Ug1, only occurred 'at' or 'ahead of' the epidemic 'front', sometimes in mixtures with Ug2. Comparison of mitochondrial cytochrome oxidase I gene sequences for Ug1 and Ug2 and well-studied B. tabaci reference populations indicated that the two Ugandan populations exhibited ≅ 8% divergence, suggesting they represent distinct sub-Saharan African lineages. Neither Ugandan genotype cluster was identified as the widely distributed, polyphagous, and highly fecund B biotype of Old World origin, with which they both diverged by ≅ 8%. Within genotype cluster divergence of Ug1 at 0.61±0.1% was twice that of Ug2 at 0.35±0.1%. Mismatch analysis suggested that Ug2 has undergone a recent population expansion and may be of non-Ugandan origin, whereas Ug1 has diverged more slowly, and is likely to be an indigenous genotype cluster.
• Legg, J. P., French, R., Rogan, D., Okao-Okuja, G., & Brown, J. K. (2002). A distinct Bemisia tabaci (Gennadius) (Hemiptera: Sternorrhyncha: Aleyrodidae) genotype cluster is associated with the epidemic of severe cassava mosaic virus disease in Uganda. Molecular Ecology, 11(Issue 7). doi:10.1046/j.1365-294x.2002.01514.x
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  During the 1990s, an epidemic of cassava mosaic virus disease caused major losses to cassava production in Uganda. Two factors associated with the epidemic were the occurrence of a novel recombinant begomovirus, EACMV-Ug, and unusually high populations of the whitefly vector, Bemisia tabaci. Here we present molecular evidence for the occurrence of two cassava-colonizing B. tabaci genotype clusters, Ug1 and Ug2, one of which, Ug2, can be consistently associated with the CMD epidemic in Uganda at the time of collection in 1997. By contrast, a second genotype cluster, Ug1, only occurred 'at' or 'ahead of' the epidemic 'front', sometimes in mixtures with Ug2. Comparison of mitochondrial cytochrome oxidase I gene sequences for Ug1 and Ug2 and well-studied B. tabaci reference populations indicated that the two Ugandan populations exhibited ≅ 8% divergence, suggesting they represent distinct sub-Saharan African lineages. Neither Ugandan genotype cluster was identified as the widely distributed, polyphagous, and highly fecund B biotype of Old World origin, with which they both diverged by ≅ 8%. Within genotype cluster divergence of Ug1 at 0.61±0.1% was twice that of Ug2 at 0.35±0.1%. Mismatch analysis suggested that Ug2 has undergone a recent population expansion and may be of non-Ugandan origin, whereas Ug1 has diverged more slowly, and is likely to be an indigenous genotype cluster.
• Morin, S., Williamson, M. S., Goodson, S. J., Brown, J. K., Tabashnik, B. E., & Dennehy, T. J. (2002). Mutations in the Bemisia tabaci para sodium channel gene associated with resistance to a pyrethroid plus organophosphate mixture. Insect Biochemistry and Molecular Biology, 32(12), 1781-1791.
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  PMID: 12429130;Abstract: The voltage-gated sodium channel is the primary target site of pyrethroid insecticides. In some insects, super knockdown resistance (super-kdr) to pyrethroids is caused by point mutations in the linker fragment between transmembrane segments 4 and 5 of the para-type sodium channel protein domain II (IIS4-5). Here, we identify two mutations in the IIS4-5 linker of the para-type sodium channel of the whitefly, Bemisia tabaci: methionine to valine at position 918 (M918V) and leucine to isoleucine at position 925 (L925I). Although each mutation was isolated independently from strains >100-fold resistant to a pyrethroid (fenpropathrin) plus organophosphate (acephate) mixture, only L925I was associated with resistance in strains derived from the field in 2000 and 2001. The L925I mutation occurred in all individuals from nine different field collections that survived exposure to a discriminating concentration of fenpropathrin plus acephate. Linkage analysis of hemizygous male progeny of unmated heterozygous F1 females (L925Ixwild-type) shows that the observed resistance is tightly linked to the voltage-gated sodium channel locus. The results provide a molecular tool for better understanding, monitoring and managing pyrethroid resistance in B. tabaci. © 2002 Elsevier Science Ltd. All rights reserved.
• Morin, S., Williamson, M. S., Goodson, S. J., Brown, J. K., Tabashnik, B. E., & Dennehy, T. J. (2002). Mutations in the Bemisia tabaci para sodium channel gene associated with resistance to a pyrethroid plus organophosphate mixture. Insect Biochemistry and Molecular Biology, 32(Issue 12). doi:10.1016/s0965-1748(02)00137-6
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  The voltage-gated sodium channel is the primary target site of pyrethroid insecticides. In some insects, super knockdown resistance (super-kdr) to pyrethroids is caused by point mutations in the linker fragment between transmembrane segments 4 and 5 of the para-type sodium channel protein domain II (IIS4-5). Here, we identify two mutations in the IIS4-5 linker of the para-type sodium channel of the whitefly, Bemisia tabaci: methionine to valine at position 918 (M918V) and leucine to isoleucine at position 925 (L925I). Although each mutation was isolated independently from strains >100-fold resistant to a pyrethroid (fenpropathrin) plus organophosphate (acephate) mixture, only L925I was associated with resistance in strains derived from the field in 2000 and 2001. The L925I mutation occurred in all individuals from nine different field collections that survived exposure to a discriminating concentration of fenpropathrin plus acephate. Linkage analysis of hemizygous male progeny of unmated heterozygous F1 females (L925Ixwild-type) shows that the observed resistance is tightly linked to the voltage-gated sodium channel locus. The results provide a molecular tool for better understanding, monitoring and managing pyrethroid resistance in B. tabaci. © 2002 Elsevier Science Ltd. All rights reserved.
• Rogan, D. M., Idris, A. M., Brown, J. K., & Bird, J. (2002). Molecular Characterization of Rhynchosia mosaic virus-Puerto Rico Associated with Symptomatic Rhynchosia minima and Cajanus cajan in Puerto Rico.. Plant disease, 86(5), 558. doi:10.1094/pdis.2002.86.5.558c
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  A begomovirus (family Geminiviridae) has long been suspected to be associated with Rhynchosia mosaic (RhM) disease of Rhynchosia minima (L.) DC., a weed that is widespread in Puerto Rico (PR). The suspect virus has been transmitted by the Sida biotype of Bemisia tabaci (Genn.) and has been designated RhM virus-PR (RhMV-PR) (1) (synonym, Rhynchosia mosaic virus [RMV]). RhM symptoms in R. minima included yellow foliar mosaic and stunting. The virus has a broad experimental host range and infects species in the Fabaceae, including R. minima, pigeon pea (Cajanus cajan (L.) Millsp.), and Clitoria falcata L. (1). However, until now RhMV has not been identified from naturally infected pigeon pea or Clitoria falcata. R. minima and C. cajan plants exhibiting yellow foliar mosaic and stunting symptoms were collected in Puerto Rico. Using the B biotype of B. tabaci as the vector, their whitefly transmissibility from the respective source plant to R. minima and C. cajan test plants was confirmed, and symptoms in inoculated host were indistinguishable for both isolates. Using polymerase chain reaction (PCR) and primers (2), three amplicons were obtained and cloned for each isolate. PCR products (1.1 and 2.1 kbp) were assembled (~200 nucleotide [nt] overlap) to yield an apparent full-length DNA A component (~2.6 kbp) containing the diagnostically informative viral coat protein gene (CP) and common region (CR-A). PCR primers were used to amplify the DNA B component segment (0.7 kbp) containing the CR-B (2). The DNA sequence for the core CP (533 nt) and full CP (750 nt) were compared with analogous sequences for well-studied begomoviruses, and CR-A and CR-B (153 nt) were compared for RhMV isolates. All isolates noted were obtained from GenBank. The core CP for isolates from R. minima (AF442117) and C. cajan (AY062025) shared 97.9% nucleotide identity (100% AA similarity) and the CR-A (AF442118) and CR-B (AF442119) sequences for R. minima and C. cajan isolates were ~96% identical, indicating the A and B components are of the same begomovirus. Comparison of the core CP sequence for an independent isolate from C. cajan from PR (AY028308) (4) with those for R. minima and C. cajan isolates indicated 95.5% (99.4% AA) and 96.2% (99.4% AA) nucleotide identity, respectively, indicating association of RhMV with both C. cajan samples. The recently archived core CP (533 nt) (AY028308) is actually of RhMV-PR, rather than a distinct begomovirus species, as indicated (4). Interestingly, the core CP of R. minima (AF442117) and C. cajan (AY062025) isolates were 91.7% (98.9% AA) and 92.3% (98.9% AA) identical, respectively, with a PR isolate from Clitoria falcata (AF070924), also confirming that RhMV-PR naturally infects Clitoria falcata. Analysis of the full CP for the R. minima and C. cajan isolates revealed that their closest relatives were Macroptilium mosaic virus (MaMV-PR) (AF176092) and Bean golden mosaic virus (BGMV-PR) (M10070) at 89 and 84% nucleotide identity, respectively. Applying the 90% CP rule (3) to RhMV CP sequences, RhMV is a distinct begomovirus species. At least three begomoviruses, BGMV-PR, MaMV-PR, and RhMV-PR, naturally infect leguminous species in Puerto Rico. References: (1) J. Bird. Phytopathology 52:286, 1962. (2) A. M. Idris and J. K. Brown. Phytopathology 88:648, 1998. (3) M. A. Mayo and C. R. Pringle. J. Gen. Virol. 79:649, 1998. (4) R. L. Rodriguez et al. Plant Dis. 85:1119, 2001.
• Zchori-Fein, E., & Brown, J. K. (2002). Diversity of prokaryotes associated with Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). Annals of the Entomological Society of America, 95(6), 711-718.
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  Abstract: Whiteflies (suborder Sternorrhyncha, family Aleyrodidae) are known to harbor prokaryotic symbionts, some of which are vital and provide specific nutritional needs, while others are transient or nonessential, that can either be beneficial or deleterious in the long-term. However, the extent to which diverse bacterial symbionts are associated with populations of the same species of whitefly that colonize herbaceous plants in diverse habitats, and their particular influence on the evolution of the whitefly host, are not well studied. Here, the composition and diversity of prokaryotic symbionts associated with biotypes or haplotypes of the whitefly Bemisia tabaci Gennadius were examined for collections from representative host plants and different geographical locations worldwide. The eubacterial 16S ribosomal DNA (rDNA) and Wolbachia-specific 16S rDNA genes for endosymbionts were obtained by polymerase chain reaction (PCR) amplification. Amplification and comparison of 16S rDNA sequences revealed that a primary-like symbiont was associated with all whitefly collections examined. However, the endosymbiont 16S rDNA phylogeny was not strictly concordant with the phylogeographically informative cytochrome oxidase I tree for the respective whitefly host. Secondary symbiont sequences for 13 of 20 whitefly populations clustered with Arsenophonus spp. and aphid T-type bacteria, which both belong to the Enterobacteriaceae. PCR and sequencing of Wolbachia-specific 16S rDNA revealed that at least 33% of B. tabaci populations harbored Wolbachia.
• Zchori-Fein, E., & Brown, J. K. (2002). Diversity of prokaryotes associated with Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). Annals of the Entomological Society of America, 95(Issue 6). doi:10.1603/0013-8746(2002)095[0711:dopawb]2.0.co;2
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  Whiteflies (suborder Sternorrhyncha, family Aleyrodidae) are known to harbor prokaryotic symbionts, some of which are vital and provide specific nutritional needs, while others are transient or nonessential, that can either be beneficial or deleterious in the long-term. However, the extent to which diverse bacterial symbionts are associated with populations of the same species of whitefly that colonize herbaceous plants in diverse habitats, and their particular influence on the evolution of the whitefly host, are not well studied. Here, the composition and diversity of prokaryotic symbionts associated with biotypes or haplotypes of the whitefly Bemisia tabaci Gennadius were examined for collections from representative host plants and different geographical locations worldwide. The eubacterial 16S ribosomal DNA (rDNA) and Wolbachia-specific 16S rDNA genes for endosymbionts were obtained by polymerase chain reaction (PCR) amplification. Amplification and comparison of 16S rDNA sequences revealed that a primary-like symbiont was associated with all whitefly collections examined. However, the endosymbiont 16S rDNA phylogeny was not strictly concordant with the phylogeographically informative cytochrome oxidase I tree for the respective whitefly host. Secondary symbiont sequences for 13 of 20 whitefly populations clustered with Arsenophonus spp. and aphid T-type bacteria, which both belong to the Enterobacteriaceae. PCR and sequencing of Wolbachia-specific 16S rDNA revealed that at least 33% of B. tabaci populations harbored Wolbachia.
• Brown, J. K., Idris, A. M., & Smith, S. E. (2001). Ingestion, transmission, and persistence of Chino del tomate virus (CdTV), a New World begomovirus, by Old and New World biotypes of the whitefly vector Bemisia tabaci. Annals of Applied Biology, 139(1), 145-154. doi:10.1111/j.1744-7348.2001.tb00139.x
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  Summary Two whitefly biotypes of Bemisia tabaci, from either the Eastern or Western Hemisphere, respectively, were compared with respect to their competency to ingest and their efficiency to transmit the New World begomovirus, Chino del tomate virus (CdTV). The AZ A biotype of B.tabaci originates from the arid southwestern USA and northwestern Mexico, while the B biotype has an origin in the Middle East or Northern Africa. The ability of these two vector biotypes to ingest and subsequently to transmit CdTV were evaluated for an acquisition-access period (AAP) that ranged from 0 to 72 h, followed by a 48 h inoculation-access period (IAP). Individual adult whiteflies were monitored for CdTV ingestion using polymerase chain reaction (PCR) to detect the viral coat protein gene (AV1 ORF), and transmission efficiency (frequency) was determined by allowing potentially viruliferous whiteflies access to tomato seedlings following each experimental AAP. PCR results for individual adult whiteflies indicated that CdTV was ingested from infected tomato plants by both biotypes 93% of the time. Transmission frequencies by both vector biotypes increased with longer AAPs. However, the AZ A biotype transmitted CdTV 50% of the time, compared to only 27% for the B biotype. Evidence that virus was ingested with equal competency by the A and B biotypes confirmed that both vectors were capable of ingesting CdTV from tomato at the same frequency, even when the AAP was 0.5 h. Consequently, either the acquisition and/or transmission stages of the pathway, rather than ingestion competency, were responsible for differences in vector-mediated transmissibility. Detection frequency of CdTV, after 48 h AAP, by PCR in single females of AZ B biotype was significantly higher than males.
• Brown, J. K., Idris, A. M., Torres-Jerez, I., Banks, G. K., & Wyatt, S. D. (2001). The core region of the coat protein gene is highly useful for establishing the provisional identification and classification of begomoviruses. Archives of Virology, 146(8), 1581-1598.
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  PMID: 11676419;Abstract: Polymerase chain reaction (PCR) was applied to detect and establish provisional identity of begomoviruses through amplification of a ∼ 575 bp fragment of the begomoviral coat protein gene (CP), referred to as the 'core' region of the CP gene (core CP). The core CP fragment contains conserved and unique regions, and was hypothesized to constitute a sequence useful for begomovirus classification. Virus relationships were predicted by distance and parsimony analyses using the A component (bipartite viruses) or full genome (monopartite viruses), CP gene, core CP, or the 200 5′-nucleotides (nt) of the CP. Reconstructed trees and sequence divergence estimates yielded very similar conclusions for all sequence sets, while the CP 5′-200 nt was the best strain discriminator. Alignment of the core CP region for 52 field isolates with reference begomovirus sequences permitted provisional virus identification based on tree position and extent of sequence divergence. Geographic origin of field isolates was predictable based on phylogenetic separation of field isolates examined here. A 'closest match' or genus-level identification could be obtained for previously undescribed begomoviruses using the BLAST program to search a reference core CP database located at our website and/or in GenBank. Here, we describe an informative molecular marker that permits provisional begomovirus identification and classification using a begomoviral sequence that is smaller than the presently accepted, but less accessible CP sequence.
• Brown, J. K., Idris, A. M., Torres-Jerez, I., Banks, G. K., & Wyatt, S. D. (2001). The core region of the coat protein gene is highly useful for establishing the provisional identification and classification of begomoviruses. Archives of Virology, 146(Issue 8). doi:10.1007/s007050170080
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  Polymerase chain reaction (PCR) was applied to detect and establish provisional identity of begomoviruses through amplification of a ∼ 575 bp fragment of the begomoviral coat protein gene (CP), referred to as the 'core' region of the CP gene (core CP). The core CP fragment contains conserved and unique regions, and was hypothesized to constitute a sequence useful for begomovirus classification. Virus relationships were predicted by distance and parsimony analyses using the A component (bipartite viruses) or full genome (monopartite viruses), CP gene, core CP, or the 200 5′-nucleotides (nt) of the CP. Reconstructed trees and sequence divergence estimates yielded very similar conclusions for all sequence sets, while the CP 5′-200 nt was the best strain discriminator. Alignment of the core CP region for 52 field isolates with reference begomovirus sequences permitted provisional virus identification based on tree position and extent of sequence divergence. Geographic origin of field isolates was predictable based on phylogenetic separation of field isolates examined here. A 'closest match' or genus-level identification could be obtained for previously undescribed begomoviruses using the BLAST program to search a reference core CP database located at our website and/or in GenBank. Here, we describe an informative molecular marker that permits provisional begomovirus identification and classification using a begomoviral sequence that is smaller than the presently accepted, but less accessible CP sequence.
• Ghanim, M., Rosell, R. C., Campbell, L. R., Czosnek, H., Brown, J. K., & Ullman, D. E. (2001). Digestive, salivary, and reproductive organs of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) B type. Journal of Morphology, 248(1), 22-40.
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  PMID: 11268056;Abstract: A microscopic analysis of the morphology and ultrastructure of the digestive, salivary, and reproductive systems of adult Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) B type was conducted using light, scanning, and transmission electron microscopy. The internal anatomy of B. tabaci was found to be similar to that reported for Trialeurodes vaporariorum. In a microscopic analysis of the salivary glands, we have shown that each primary salivary gland is composed of at least 13 cells varying in morphology and staining differentially, while the accessory salivary glands are composed of four morphologically similar cells. We analyzed the course of the alimentary canal in B. tabaci, demonstrated the internal morphology of the organs, and clarified the location of the filter chamber relative to other organs in the whitefly. Our observations confirm that the pair of structures extending from the connecting chamber are caeca that may aid in fluid movement through the midgut and are not Malpighian tubules, as previously suggested. We confirm an earlier finding that the whitefly lacks Malpighian tubules, having instead specialized Malpighian-like cells within the filter chamber at the juncture with the internal ileum. Finally, we provide the first scanning electron microscopic analysis showing the reproductive organs of B. tabaci. Our investigation provides clarified terminology for several components of the digestive and excretory system. We also provide drawings and micrographs that will aid future researchers in localizing the internal organs of B. tabaci. We expect our analysis to provide a valuable tool for studying B. tabaci / plant virus interactions and physiological and biological aspects of this insect. © 2001 Wiley-Liss, Inc.
• Ghanim, M., Rosell, R. C., Campbell, L. R., Czosnek, H., Brown, J. K., & Ullman, D. E. (2001). Digestive, salivary, and reproductive organs of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) B type. Journal of Morphology, 248(Issue 1). doi:10.1002/jmor.1018
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  A microscopic analysis of the morphology and ultrastructure of the digestive, salivary, and reproductive systems of adult Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) B type was conducted using light, scanning, and transmission electron microscopy. The internal anatomy of B. tabaci was found to be similar to that reported for Trialeurodes vaporariorum. In a microscopic analysis of the salivary glands, we have shown that each primary salivary gland is composed of at least 13 cells varying in morphology and staining differentially, while the accessory salivary glands are composed of four morphologically similar cells. We analyzed the course of the alimentary canal in B. tabaci, demonstrated the internal morphology of the organs, and clarified the location of the filter chamber relative to other organs in the whitefly. Our observations confirm that the pair of structures extending from the connecting chamber are caeca that may aid in fluid movement through the midgut and are not Malpighian tubules, as previously suggested. We confirm an earlier finding that the whitefly lacks Malpighian tubules, having instead specialized Malpighian-like cells within the filter chamber at the juncture with the internal ileum. Finally, we provide the first scanning electron microscopic analysis showing the reproductive organs of B. tabaci. Our investigation provides clarified terminology for several components of the digestive and excretory system. We also provide drawings and micrographs that will aid future researchers in localizing the internal organs of B. tabaci. We expect our analysis to provide a valuable tool for studying B. tabaci / plant virus interactions and physiological and biological aspects of this insect. © 2001 Wiley-Liss, Inc.
• Idris, A. M., & Brown, J. K. (2001). Three Previously Unidentified Begomoviral Genotypes from Tomato Exhibiting Leaf Curl Disease Symptoms from Central Sudan.. Plant disease, 85(11), 1209. doi:10.1094/pdis.2001.85.11.1209a
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  Field tomato plants exhibiting upward curling of leaflets, chlorosis, and stunting symptoms described for tomato leaf curl disease in Sudan (2) were collected in 1996 from Gezira (GZ) and Shambat (SH), Sudan. Disease symptoms were reproduced following experimental transmission of the causal agent(s) by the whitefly Bemisia tabaci from field tomato to virus-free tomato seedlings in a glasshouse at Gezira Research Station, Wad Medani, Sudan. Total nucleic acids were extracted from symptomatic tomato test plants. An ≈1.3-kbp fragment, diagnostic for begomovirus, was obtained from extracts by polymerase chain reaction using degenerate primers that amplify the coat protein gene (CP) and the respective flanking sequences for most begomoviuses (1). A second pair of degenerate primers was used to amplify a 2.3-kbp begomoviral fragment that overlaps both ends of the (CP) amplicon by >200 nt (1). At least 10 amplicons for each were cloned, and their sequences were determined, revealing three unique, tomato-infecting begomoviruses genotypes, two from GZ and one from SH. No B component was detected using degenerate primers that direct the amplification of a diagnostic fragment of the B component (1.4 kbp) for most bipartite begomoviruses. The organization of the three, apparently full-length viral genomes, was typical of other monopartite begomoviruses. A GenBank search revealed that the three viruses were previously undescribed. The GZ and SH tomato isolates are herein provisionally named ToLCV-GZ1 (GenBank Accession No. AY044137), ToLCV-GZ2 (GenBank Accession No. AY044138), and ToLCV-SH (GenBank Accession No. AY044139), respectively. All three tomato-infecting begomoviruses have identical stem-loop structures containing the conserved nonanucleotide motif characteristic of all members of the family Geminiviridae; however, the predicted Rep binding element located in the common region is unique for each virus. Phylogenetic analysis of the three viral sequences placed them in a large clade containing all other Old World begomoviruses. Distance comparisons among these and other well-studied begomoviruses indicated that ToLCV-GZ1 and ToLCV-SH shared an overall 90% nucleotide sequence identity, with ˜83% nucleotide sequence identity to ToLCV-GZ2. ToLCV-GZ1 and ToLCV-SH were 83% identical, with their closest relative, Tomato yellow leaf curl virus (TYLCV), while ToLCV-GZ2 shared 93% identity with TYLCV. The genomes of all three Sudan viruses contained regions of homologous nucleotide sequences, suggesting intermolecular exchange among these viruses. Exclusion of the homologous sequences (>800 nt) from the phylogenetic analysis indicated even lower shared nucleotide identities (
• Idris, A., Smith, S., & Brown, J. (2001). Ingestion, transmission, and persistence of Chino del tomate virus (CdTV), a new world begomovirus, by old and new world biotypes of the whitefly vector Bemisia tabaci. Annals of Applied Biology, 139, 145-154. doi:10.1111/j.1744-7348.2001.tb00139.x
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  Two whitefly biotypes of Bemisia tabaci, from either the Eastern or Western Hemisphere, respectively, were compared with respect to their competency to ingest and their efficiency to transmit the New World begomovirus, Chino del tomate virus (CdTV). The AZ A biotype of B. tabaci originates from the arid southwestern USA and northwestern Mexico, while the B biotype has an origin in the Middle East or Northern Africa. The ability of these two vector biotypes to ingest and subsequently to transmit CdTV were evaluated for an acquisition-access period (AAP) that ranged from 0 to 72 h, followed by a 48 h inoculation-access period (IAP). Individual adult whiteflies were monitored for CdTV ingestion using polymerase chain reaction (PCR) to detect the viral coat protein gene (AV1 ORF), and transmission efficiency (frequency) was determined by allowing potentially viruliferous whiteflies access to tomato seedlings following each experimental AAP. PCR results for individual adult whiteflies indicated that CdTV was ingested from infected tomato plants by both biotypes 93% of the time. Transmission frequencies by both vector biotypes increased with longer AAPs. However, the AZ A biotype transmitted CdTV 50% of the time, compared to only 27% for the B biotype. Evidence that virus was ingested with equal competency by the A and B biotypes confirmed that both vectors were capable of ingesting CdTV from tomato at the same frequency, even when the AAP was 0.5 h. Consequently, either the acquisition and/or transmission stages of the pathway, rather than ingestion competency, were responsible for differences in vector-mediated transmissibility. Detection frequency of CdTV, after 48 h AAP, by PCR in single females of AZ B biotype was significantly higher than males.
• Rogan, D., Idris, A. M., Brown, J. K., & Bird, J. (2001). Introduction of the Exotic Tomato yellow leaf curl virus-Israel in Tomato to Puerto Rico.. Plant disease, 85(9), 1028. doi:10.1094/pdis.2001.85.9.1028b
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  Thirty-five-day-old tomato plants (cultivar Florasette) exhibited yellow leaf curling, stunting, and extremely reduced fruit set in spring 2001, in Guanica, Puerto Rico (PR). Twenty percent disease incidence was observed in this field and, 8 weeks later, 75% of the plants showed symptoms. These symptoms were distinct from those caused by other tomato-infecting begomoviruses reported previously from PR, namely Merremia mosaic virus, Tomato mottle virus (ToMoV), and Potato yellow mosaic virus (1). A colony of the B biotype of Bemisia tabaci (Genn.) was used to transmit the suspect virus from symptomatic plants collected in the field and established in the greenhouse in Rio Piedras, PR. The suspect virus was transmitted readily to tomato cultivar Roma (10 of 10 plants), and symptoms were like those observed in the field. Symptoms also were reminiscent of those described for several Old World begomoviruses, referred to as Tomato yellow leaf curl virus (TYLCV). Total nucleic acids were isolated from three symptomatic field samples and three greenhouse-inoculated tomato plants showing typical disease symptoms. Extracts were analyzed by polymerase chain reaction (PCR) with primers AV2466 and AC1145 to amplify a begomoviral fragment (approximately 1.1 bp) that contains a portion of the intergenic region and the viral coat protein gene (CP) (2). Amplicons were cloned, and their nucleotide sequences were determined. A comparison of CP with other well-studied begomoviral nucleotide sequences revealed that the CP sequences for field isolates 1 to 6 shared 99.7 to 100% identity with each other and 99.9 to 100% identity with TYLCV from Israel (TYLCV-IL; accession no. X76319) as well as TYLCV-IL isolates discovered in the Dominican Republic (DO; accession no. AF024715) and, subsequently, in Florida. TYLCV-specific PCR primers (forward) 5'-GAATTCCGCCTTTAA-TTTG-3' and (reverse) 5'-GAATTCCCACTATCTTTCTC-3' were used to amplify the complete viral genome form a PR field isolate. An expected-sized amplicon of approximately 2.8 kb was obtained, and the nucleotide sequence of two cloned amplicons was determined. Genome organization revealed a predicted precoat open reading frame of 351 bp, which is characteristic of other Old World begomoviruses, including TYLCV-IL. Nucleotide comparisons indicated that the PR isolate shared 99% nucleotide sequence identity with TYLCV-IL (first reported from Israel) and introduced TYLCV-IL isolates in DO and Florida, thereby confirming the introduction of TYLCV-IL into PR. TYLCV-IL was first identified several years ago in the Western Hemisphere, and the virus has been reported in five offshore locations and three continental U.S. states since its initial introduction into the DO in the early 1990s. Considering the extreme virulence of TYLCV-IL compared with most New World tomato-infecting begomoviruses, this introduction, which likely occurred from a nearby Caribbean country or Florida, has the potential to destroy the fresh-market tomato industry in PR, which supplies tomatoes to the continental United States during the winter months. There is compelling evidence for the routine movement of tomato seedlings from the continental United States to this location in PR throughout the last 10 years, including the previous introduction of ToMoV (1). These incidences and others indicate the need for those in infected areas to take precautions to avoid further spread of this highly damaging virus in and adjacent to the Caribbean region. References: (1) A. M. Idris et al. Phytopathology 88:S42, 1998. (2) A. M. Idris and J. K. Brown, Phytopathology 88:648, 1998.
• Rogan, D., Palmieri, M., Idris, A. M., Hussein, M. H., & Brown, J. K. (2001). Melon chlorotic leaf curl virus, a New Begomovirus Associated with Bemisia tabaci Infestations in Guatemala.. Plant disease, 85(9), 1027. doi:10.1094/pdis.2001.85.9.1027c
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  In 2000, geminivirus-like symptoms were widespread in muskmelon (Cucumis melo L.) fields (70 to 80% incidence) in Zacapa Valley, Guatemala. Muskmelon fields were infested with the whitefly Bemisia tabaci (Genn.), and plants exhibited patchy foliar chlorosis, leaf curling, and reduced fruit set, which is reminiscent of symptoms caused by certain whitefly-transmitted geminiviruses. Quarantine restrictions prevented experimental transmission experiments from being carried out with the whitefly vector or biolistic inoculation. Leaves collected from six symptomatic plants were assessed for the presence of begomovirus DNA by polymerase chain reaction (PCR) with the use of degenerate primers that amplify the core region of the coat protein (CP) gene of most begomoviruses (1). PCR products of the expected size (approximately 576 bp) were obtained from all three melon samples. The core CP amplicons were cloned, and their nucleotide sequences were compared. Nucleotide sequences of core CP fragments shared 99.7% identity, suggesting the presence of a single begomovirus in all assayed symptomatic melon plants. Two additional pairs of degenerate primers were used to obtain contiguous viral fragments containing the CP gene, the common region of the A component (CR-A; approximately 2,100 bp), and a fragment containing the CR of the B component (CR-B; approximately 1,100 bp), respectively (2). At least three amplicons obtained with each primer pair were cloned and their nucleotide sequence was determined. Virus-specific PCR primers were then designed within the CP open reading frame and used to obtain fragments that overlapped with the 2,100-bp fragment to yield an apparent full-length A component of 2,662 nucleotides (accession no. AF325497). CR-A and CR-B (accession no. AF325498) sequences (161 nucleotides) shared 98.1% identity and contained an identical directly repeated, replication-associated protein (REP) binding site: GGTGT CCT GGTGT. Nucleotide sequence alignment, with CLUSTAL W, of the melon virus A-component with that of other well-studied begomoviruses revealed that its closest relatives were members of the Squash leaf curl virus (SLCV) group. The melon virus from Guatemala shared its greatest sequence identity, 83.1%, with SLCV extended (SLCV-E) (accession no. M38183), indicating that it is a new, previously unidentified begomovirus species, herein referred to as Melon chlorotic leaf curl virus (MCLCV). The next closest relatives of MCLCV were SLCV restricted (SLCV-R; 78.6%) (S. G. Lazarowitz, unpublished) Cucurbit leaf curl virus-Arizona (CuLCV-AZ; accession no. AF256199; 74.1%) (3), Cabbage leaf curl virus (CaLCV; 72.0%), Bean calico mosaic virus (BCMoV; 71.7%), and Texas pepper virus-Tamaulipas (71.4%). Additionally, the theoretical REP binding element, GGTGT, is 100% identical among MCLCV and BCMoV, CaLCV, CuLCV-AZ, SLCV-E, and SLCV-R. On the basis of shared nucleotide sequence identities with other begomoviruses described to date and the presence of B. tabaci in melon fields, it is likely that MCLCV also is whitefly-transmitted. Collectively, CP and CR sequences suggest that MCLCV is a new species of the SLCV lineage that contains other bipartite begomoviruses indigenous to Central America, Mexico, and the U.S. Sunbelt states. References: (1) S. D. Wyatt and J. K. Brown. Phytopathology 86:1288, 1996. (2) A. M. Idris and J. K Brown. Phytopathology 88:648, 1998. (3) J. K. Brown et al. Plant Dis. 84:809, 2000.
• Zchori-Fein, E., Gottlieb, Y., Kelly, S. E., Brown, J. K., Wilson, J. M., Karr, T. L., & Hunter, M. S. (2001). A newly discovered bacterium associated with parthenogenesis and a change in host selection behavior in parasitoid wasps. Proceedings of the National Academy of Sciences of the United States of America, 98(22), 12555-12560.
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  PMID: 11592990;PMCID: PMC60092;Abstract: The symbiotic bacterium Wolbachia pipientis has been considered unique in its ability to cause multiple reproductive anomalies in its arthropod hosts. Here we report that an undescribed bacterium is vertically transmitted and associated with thelytokous parthenogenetic reproduction in Encarsia, a genus of parasitoid wasps. Although Wolbachia was found in only one of seven parthenogenetic Encarsia populations examined, the "Encarsia bacterium" (EB) was found in the other six. Among seven sexually reproducing populations screened, EB was present in one, and none harbored Wolbachia. Antibiotic treatment did not induce male production in Encarsia pergandiella but changed the oviposition behavior of females. Cured females accepted one host type at the same rate as control females but parasitized significantly fewer of the other host type. Phylogenetic analysis based on the 16S rDNA gene sequence places the EB in a unique clade within the Cytophaga-Flexibacter-Bacteroid group and shows EB is unrelated to the Proteobacteria, where Wolbachia and most other insect symbionts are found. These results imply evolution of the induction of parthenogenesis in a lineage other than Wolbachia. Importantly, these results also suggest that EB may modify the behavior of its wasp carrier in a way that enhances its transmission.
• Zchori-Fein, E., Gottlieb, Y., Kelly, S. E., Brown, J. K., Wilson, J. M., Karr, T. L., & Hunter, M. S. (2001). A newly discovered bacterium associated with parthenogenesis and a change in host selection behavior in parasitoid wasps. Proceedings of the National Academy of Sciences of the United States of America, 98(Issue 22). doi:10.1073/pnas.221467498
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  The symbiotic bacterium Wolbachia pipientis has been considered unique in its ability to cause multiple reproductive anomalies in its arthropod hosts. Here we report that an undescribed bacterium is vertically transmitted and associated with thelytokous parthenogenetic reproduction in Encarsia, a genus of parasitoid wasps. Although Wolbachia was found in only one of seven parthenogenetic Encarsia populations examined, the "Encarsia bacterium" (EB) was found in the other six. Among seven sexually reproducing populations screened, EB was present in one, and none harbored Wolbachia. Antibiotic treatment did not induce male production in Encarsia pergandiella but changed the oviposition behavior of females. Cured females accepted one host type at the same rate as control females but parasitized significantly fewer of the other host type. Phylogenetic analysis based on the 16S rDNA gene sequence places the EB in a unique clade within the Cytophaga-Flexibacter-Bacteroid group and shows EB is unrelated to the Proteobacteria, where Wolbachia and most other insect symbionts are found. These results imply evolution of the induction of parthenogenesis in a lineage other than Wolbachia. Importantly, these results also suggest that EB may modify the behavior of its wasp carrier in a way that enhances its transmission.
• Anciso, J., Brown, J. K., Idris, A. M., Isakeit, T., Miller, M. E., & Olsen, M. W. (2000). Cucurbit leaf curl virus, a New Whitefly Transmitted Geminivirus in Arizona, Texas, and Mexico.. Plant disease, 84(7), 809. doi:10.1094/pdis.2000.84.7.809a
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  In 1998 to 1999, geminivirus-like symptoms were observed in whitefly-infested pumpkin, honeydew melon, and muskmelon in Arizona and Texas and in Coahuilla, Mexico (MX), respectively. Plants exhibited leaf curl and/or mottling, reminiscent of symptoms caused by Squash leaf curl virus (SLCV-WAZ) described from Arizona in 1981 (2). The isolate from Arizona pumpkin fields was experimentally transmitted to pumpkin seedlings by the "B type" of Bemisia tabaci (Genn.), and symptoms were indistinguishable from those observed in infected fields. Samples from AZ, MX, and TX were assessed for begomovirus presence by polymerase chain reaction (PCR) using degenerate primers that amplify a contiguous fragment containing the viral coat protein (Cp) gene and common region (CR) of the A component (CR-A) (~2,100 bp) and a fragment containing the CR of the B component (CR-B) (~1,100 bp). One to four isolates from each location were examined by PCR using both primer pairs, and at least three amplicons per isolate were cloned and their sequences determined. Alignment of viral Cp nucleotide (nt) sequences revealed that AZ [AF256199], MX, and TX field isolates shared 98.7 to 100% sequence identity, but were only 84.5 to 85.6% identical to the Cp gene of SLCV-extended (SLCV-E) [M38183] and SLCV-restricted (SLCV-R) (S. G. Lazarowitz, unpublished), respectively, suggesting a new, previously undescribed begomoviral species (3). Further, the Cp nt sequence of the three field isolates was 6 nt shorter than SLCV-E, SLCV-WAZ [AF256203], and SLCV-R Cp sequences. The CR-A [AF256200] and CR-B [AF256201] sequences (179 nt, each) of field isolates, including the theoretical Rep binding element, GGTGT, were 100% identical. Although the Rep binding site is identical among field isolates, SLCV-E, SLCV-R, and SLCV-WAZ, the field isolate CR sequence shared only 64.2, 67.5, and 66.9% overall identity with CR-A SLCV-E, SLCV-R [M63155], and SLCV-WAZ [AF256202], respectively. Prior to 1998 to 1999, SLCV-WAZ was the only New World begomovirus of cucurbits known to infect both melon (Cucumis) and pumpkin (Cucurbita) (1). Therefore, SLCV was initially suspected as the causal agent. However, here we provide evidence for a new, previously undescribed bipartite begomovirus of cucurbits in AZ, MX, and TX that is herein provisionally designated Cucurbit leaf curl virus (CuLCV). Prediction of its closest begomovirus relatives by Cp nt sequence and Rep binding site comparisons suggest that CuLCV is a new member of the SLCV lineage, also containing Bean calico mosaic virus, Cabbage leaf curl virus, SLCV-E, and Texas pepper virus-TAM. References: (1) J. K. Brown and M. R. Nelson. Phytopathology 74:1136, 1984. (2) J. K. Brown and M. R. Nelson. Ann. Appl. Biol. 115:243, 1986. (3) M. A. Mayo and C. R. Pringle. J. Gen. Virol. 97:649, 1998.
• Brown, J. K. (2000). Molecular markers for the identification and global tracking of whitefly vector-Begomovirus complexes. Virus Research, 71(1-2), 233-260.
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  PMID: 11137175;Abstract: Recent unprecedented upsurges in populations of the whitefly Bemisia tabaci (Genn.) have drawn much attention to its worldwide importance as an insect pest and as the vector of emergent begomoviruses (Family: Geminiviridae; Genus: Begomovirus). Several begomoviruses that are considered 'new' and others previously regarded as minor pathogens have been linked to recent epidemics. Recent studies have revealed much variation in begomoviruses, despite the view that DNA-containing viruses do not rapidly accumulate mutations. Also, certain B. tabaci 'variants' are known that more effectively or selectively transmit certain begomoviruses and exhibit biotic differences that may influence their spread. Patterns of distribution and dissemination of begomoviruses transmitted by B. tabaci are poorly understood because standardized molecular-based tracking methods have not been available. Understanding virus/whitefly vector/host plant interrelationships in the context of emerging problems can be achieved only by linking predicted evolutionary histories with epidemiology using molecular phylogenetic approaches. Identification and validation of informative molecular sequences are essential initial steps in this process. Genus-wide degenerate polymerase chain reaction (PCR) primers have been developed to amplify and sequence the 'core' region of the coat protein open reading frame (ORF) (V1), permitting 'universal' detection and provisional virus identification by comparisons with described viral genotypes. In subsequent studies reported here, several potentially informative viral ORFs and a non-coding region are explored. Of particular use for expanding diversity studies are group- or virus-specific sequences that can be targeted by utilizing newly available core CP sequences, or additional conserved regions around which broad spectrum primers can be designed to target variable sequences in key ORFs or non-coding regions. Prospective markers under exploration were selected with a basis in the most highly conserved viral ORFs, CP (V1) and a portion of replication-associated protein (REP) (L1/C1), and a key non-coding sequence that contain sufficient variability and/or virus-specific sequences, and are consequently of potential epidemiological relevance. Because B. tabaci occurs as a cryptic species, or species complex, that exhibits biotic polymorphism, yet morphological invariance, traditional morphologically based identification is impossible. An overriding complication to establishing molecular markers for identifying whitefly vector variants is that whitefly sequences in general, have not been available. However, recent work has shown that a partial mitochondria cytochrome oxidase I (mt COI) sequence separates vector variants with a basis in geographical origin, suggesting it is useful for further exploring variability and the phylogenetic history of whiteflies on a large scale. Here, the utility of whitefly mt COI nucleotides (nt) sequences is illustrated for inferring relationships between B. tabaci collected from major world regions. Used collectively, these approaches permit investigations of the patterns of distribution and dissemination of begomovirus-whitefly vector complexes for the first time. Ultimately, more immediate recognition of exotic viruses and whitefly vectors and early detection of upsurges in vector populations and of emerging viruses will be possible. © 2000 Elsevier Science B.V.
• Brown, J. K. (2000). Molecular markers for the identification and global tracking of whitefly vector-Begomovirus complexes. Virus Research, 71(Issue 1-2). doi:10.1016/s0168-1702(00)00221-5
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  Recent unprecedented upsurges in populations of the whitefly Bemisia tabaci (Genn.) have drawn much attention to its worldwide importance as an insect pest and as the vector of emergent begomoviruses (Family: Geminiviridae; Genus: Begomovirus). Several begomoviruses that are considered 'new' and others previously regarded as minor pathogens have been linked to recent epidemics. Recent studies have revealed much variation in begomoviruses, despite the view that DNA-containing viruses do not rapidly accumulate mutations. Also, certain B. tabaci 'variants' are known that more effectively or selectively transmit certain begomoviruses and exhibit biotic differences that may influence their spread. Patterns of distribution and dissemination of begomoviruses transmitted by B. tabaci are poorly understood because standardized molecular-based tracking methods have not been available. Understanding virus/whitefly vector/host plant interrelationships in the context of emerging problems can be achieved only by linking predicted evolutionary histories with epidemiology using molecular phylogenetic approaches. Identification and validation of informative molecular sequences are essential initial steps in this process. Genus-wide degenerate polymerase chain reaction (PCR) primers have been developed to amplify and sequence the 'core' region of the coat protein open reading frame (ORF) (V1), permitting 'universal' detection and provisional virus identification by comparisons with described viral genotypes. In subsequent studies reported here, several potentially informative viral ORFs and a non-coding region are explored. Of particular use for expanding diversity studies are group- or virus-specific sequences that can be targeted by utilizing newly available core CP sequences, or additional conserved regions around which broad spectrum primers can be designed to target variable sequences in key ORFs or non-coding regions. Prospective markers under exploration were selected with a basis in the most highly conserved viral ORFs, CP (V1) and a portion of replication-associated protein (REP) (L1/C1), and a key non-coding sequence that contain sufficient variability and/or virus-specific sequences, and are consequently of potential epidemiological relevance. Because B. tabaci occurs as a cryptic species, or species complex, that exhibits biotic polymorphism, yet morphological invariance, traditional morphologically based identification is impossible. An overriding complication to establishing molecular markers for identifying whitefly vector variants is that whitefly sequences in general, have not been available. However, recent work has shown that a partial mitochondria cytochrome oxidase I (mt COI) sequence separates vector variants with a basis in geographical origin, suggesting it is useful for further exploring variability and the phylogenetic history of whiteflies on a large scale. Here, the utility of whitefly mt COI nucleotides (nt) sequences is illustrated for inferring relationships between B. tabaci collected from major world regions. Used collectively, these approaches permit investigations of the patterns of distribution and dissemination of begomovirus-whitefly vector complexes for the first time. Ultimately, more immediate recognition of exotic viruses and whitefly vectors and early detection of upsurges in vector populations and of emerging viruses will be possible. © 2000 Elsevier Science B.V.
• Brown, J. K., & Idris, A. M. (2000). Identification of a New, Monopartite Begomovirus Associated with Leaf Curl Disease of Cotton in Gezira, Sudan. Plant Disease, 84(7), 809-809. doi:10.1094/pdis.2000.84.7.809c
• Brown, J. K., Ostrow, K. M., Idris, A. M., & Stenger, D. C. (2000). Chino del tomate virus: Relationships to other begomoviruses and identification of A-component variants that affect symptom expression. Phytopathology, 90(5), 546-552.
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  PMID: 18944562;Abstract: Phylogenetic and distance analyses place Chino del tomate virus (CdTV) in the New World clade of begomoviruses and indicate that CdTV and Tomato leaf crumple virus (TLCrV) are closely related strains of the same virus. One cloned CdTV A component (pCdTV-H6), when inoculated to tomato with the B component (pCdTV-B52), produced mild symptoms and low DNA titers. Another cloned CdTV A component (pCdTV-H8), when coinoculated to tomato with the B component, produced moderate leaf curling and veinal chlorosis similar to that of TLCrV. Coinoculation of both CdTV A components and the B component to tomato produced wild-type chino del tomate (CdT) disease symptoms consisting of severe leaf curling, veinal and interveinal chlorosis, and stunting. The two CdTV A components were nearly identical, except at nucleotide positions 1,722 and 2,324. The polymorphism at nucleotide 1,722 resulted in a change at Rep amino acid 261. The second polymorphism at nucleotide 2,324 resulted in changes at Rep amino acid 60 and AC4 amino acid 10. Two chimeric A components constructed by reciprocal exchange of a fragment bearing the polymorphic site at nucleotide 1,722 were evaluated for symptom phenotype. One chimeric A component (pCdTV-H86) produced wild-type CdT symptoms when coinoculated to tomato with the B component. The reciprocal chimeric A component (pCdTV-H68), when coinoculated to tomato with the B component, also produced severe leaf curling, veinal chlorosis, and stunting. However, pCdTV-H68 induced less obvious interveinal chlorosis than wild-type or pCdTV-H86. Examination of A component genotypes recovered from tomato coinoculated with pCdTV-H6 and pCdTV-H8 indicated that recombination occurred to produce a genotype identical to pCdTV-H86. These results indicate that subtle genotypic variation has significant effects on symptom expression and may explain phenotypic differences observed among isolates and cloned DNAs of CdTV and TLCrV.
• Brown, J. K., Ostrow, K. M., Idris, A. M., & Stenger, D. C. (2000). Chino del tomate virus: Relationships to other begomoviruses and identification of A-component variants that affect symptom expression. Phytopathology, 90(Issue 5). doi:10.1094/phyto.2000.90.5.546
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  Phylogenetic and distance analyses place Chino del tomate virus (CdTV) in the New World clade of begomoviruses and indicate that CdTV and Tomato leaf crumple virus (TLCrV) are closely related strains of the same virus. One cloned CdTV A component (pCdTV-H6), when inoculated to tomato with the B component (pCdTV-B52), produced mild symptoms and low DNA titers. Another cloned CdTV A component (pCdTV-H8), when coinoculated to tomato with the B component, produced moderate leaf curling and veinal chlorosis similar to that of TLCrV. Coinoculation of both CdTV A components and the B component to tomato produced wild-type chino del tomate (CdT) disease symptoms consisting of severe leaf curling, veinal and interveinal chlorosis, and stunting. The two CdTV A components were nearly identical, except at nucleotide positions 1,722 and 2,324. The polymorphism at nucleotide 1,722 resulted in a change at Rep amino acid 261. The second polymorphism at nucleotide 2,324 resulted in changes at Rep amino acid 60 and AC4 amino acid 10. Two chimeric A components constructed by reciprocal exchange of a fragment bearing the polymorphic site at nucleotide 1,722 were evaluated for symptom phenotype. One chimeric A component (pCdTV-H86) produced wild-type CdT symptoms when coinoculated to tomato with the B component. The reciprocal chimeric A component (pCdTV-H68), when coinoculated to tomato with the B component, also produced severe leaf curling, veinal chlorosis, and stunting. However, pCdTV-H68 induced less obvious interveinal chlorosis than wild-type or pCdTV-H86. Examination of A component genotypes recovered from tomato coinoculated with pCdTV-H6 and pCdTV-H8 indicated that recombination occurred to produce a genotype identical to pCdTV-H86. These results indicate that subtle genotypic variation has significant effects on symptom expression and may explain phenotypic differences observed among isolates and cloned DNAs of CdTV and TLCrV.
• Brown, J. K., Perring, T. M., Cooper, A. D., Bedford, I. D., & Markham, P. G. (2000). Genetic analysis of Bemisia (Hemiptera: Aleyrodidae) populations by isoelectric focusing electrophoresis. Biochemical Genetics, 38(1-2), 13-25.
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  PMID: 10862356;Abstract: Twenty-one whitefly populations in the genus Bemisia were evaluated for genetic variation at 3 allozyme loci. Nine of the 22 populations that exhibited polymorphic loci were subjected to allozyme analysis using a minimum of 10 enzymes, representing 10 to 14 distinct loci. Among those nine variants examined, calculated genetic distances ranged between 0.03 and 0.52, with three main groups emerging from the analysis. One group comprised two closely related Western Hemisphere variants of B. tabaci: type A from California, United States and a geographically proximal population from Culiacan, Mexico. A second cluster contained five collections previously identified as B. tabaci type B and Bemisia argentifolii, while a third group contained a single population from Benin, Africa. The latter two groups were grouped separately from New World populations and are thought to have a recent origin in the Eastern Hemisphere.
• Brown, J. K., Perring, T. M., Cooper, A. D., Bedford, I. D., & Markham, P. G. (2000). Genetic analysis of Bemisia (Hemiptera: Aleyrodidae) populations by isoelectric focusing electrophoresis. Biochemical Genetics, 38(Issue 1-2). doi:10.1023/a:1001806702292
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  Twenty-one whitefly populations in the genus Bemisia were evaluated for genetic variation at 3 allozyme loci. Nine of the 22 populations that exhibited polymorphic loci were subjected to allozyme analysis using a minimum of 10 enzymes, representing 10 to 14 distinct loci. Among those nine variants examined, calculated genetic distances ranged between 0.03 and 0.52, with three main groups emerging from the analysis. One group comprised two closely related Western Hemisphere variants of B. tabaci: type A from California, United States and a geographically proximal population from Culiacan, Mexico. A second cluster contained five collections previously identified as B. tabaci type B and Bemisia argentifolii, while a third group contained a single population from Benin, Africa. The latter two groups were grouped separately from New World populations and are thought to have a recent origin in the Eastern Hemisphere.
• Kirk, A. A., Lacey, L. A., Brown, J. K., Ciomperlik, M. A., Goolsby, J. A., Vacek, D. C., Wendel, L. E., & Napompeth, B. (2000). Variation in the Bemisia tabaci s. 1. species complex (Hemiptera: Aleyrodidae) and its natural enemies leading to successful biological control of Bemisia biotype B in the USA. Bulletin of Entomological Research, 90(4), 317-327.
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  PMID: 11020790;Abstract: Parasitoids of the Bemisia tabaci (Gennadius) species complex collected in Spain and Thailand were evaluated as biological control agents of B. tabaci biotype B in cole crops in Texas, USA. Parasitoids were identified by morphological and RAPD-PCR analyses. The most abundant parasitoid from Spain was Eretmocerus mundus Mercet with apparent field parasitism of 39-44%. In Thailand, Encarsia formosa Gahan, E. transvena Timberlake, E. adrianae Lopez-Avila, Eretmocerus sp. 1 and sp. 2 emerged, with apparent field parasitism of 1-65%. Identification and molecular classification of B. tabaci associated with parasitoid collections and in the release site in Texas were accomplished using morphological traits and nucleotide sequence comparison of the mitochondrial cytochrome oxidase I gene (COI) (700-720 bp). Collections of B. tabaci from Thailand grouped separately from B types from Arizona and Florida and the target B type from Texas, USA, a cluster from India, and other New World B. tabaci. The Spanish B. tabaci host of E. mundus which was laboratory and field-tested to achieve biological control of the B type was most closely related to non-B type B. tabaci populations from Spain and Sudan, the latter which formed a second group within the larger clade that also contained the B type cluster. Laboratory tests indicated that E. mundus from Spain parasitized more B. tabaci type B than did Eretmocerus spp. native to Texas and other exotic parasitoids evaluated. Eretmocerus mundus from Spain also successfully parasitized B, tabaci type B when field-released in a 0.94 million ha test area in Texas, and has significantly enhanced control of B. tabaci type B in California, USA. In contrast, parasitoids from Thailand failed to establish in the field in Texas, collectively suggesting a positive correlation between the centres of diversity of compatible parasitoid-host complexes.
• Kirk, A. A., Lacey, L. A., Brown, J. K., Ciomperlik, M. A., Goolsby, J. A., Vacek, D. C., Wendel, L. E., & Napompeth, B. (2000). Variation in the Bemisia tabaci s. 1. species complex (Hemiptera: Aleyrodidae) and its natural enemies leading to successful biological control of Bemisia biotype B in the USA. Bulletin of Entomological Research, 90(Issue 4). doi:10.1017/s0007485300000444
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  Parasitoids of the Bemisia tabaci (Gennadius) species complex collected in Spain and Thailand were evaluated as biological control agents of B. tabaci biotype B in cole crops in Texas, USA. Parasitoids were identified by morphological and RAPD-PCR analyses. The most abundant parasitoid from Spain was Eretmocerus mundus Mercet with apparent field parasitism of 39-44%. In Thailand, Encarsia formosa Gahan, E. transvena Timberlake, E. adrianae Lopez-Avila, Eretmocerus sp. 1 and sp. 2 emerged, with apparent field parasitism of 1-65%. Identification and molecular classification of B. tabaci associated with parasitoid collections and in the release site in Texas were accomplished using morphological traits and nucleotide sequence comparison of the mitochondrial cytochrome oxidase I gene (COI) (700-720 bp). Collections of B. tabaci from Thailand grouped separately from B types from Arizona and Florida and the target B type from Texas, USA, a cluster from India, and other New World B. tabaci. The Spanish B. tabaci host of E. mundus which was laboratory and field-tested to achieve biological control of the B type was most closely related to non-B type B. tabaci populations from Spain and Sudan, the latter which formed a second group within the larger clade that also contained the B type cluster. Laboratory tests indicated that E. mundus from Spain parasitized more B. tabaci type B than did Eretmocerus spp. native to Texas and other exotic parasitoids evaluated. Eretmocerus mundus from Spain also successfully parasitized B, tabaci type B when field-released in a 0.94 million ha test area in Texas, and has significantly enhanced control of B. tabaci type B in California, USA. In contrast, parasitoids from Thailand failed to establish in the field in Texas, collectively suggesting a positive correlation between the centres of diversity of compatible parasitoid-host complexes.
• Pietersen, G., Kruger, K., Idris, A. M., & Brown, J. K. (2000). Tomato curly stunt virus, a New Begomovirus of Tomato Within the Tomato yellow leaf curl virus-IS Cluster in South Africa.. Plant disease, 84(7), 810. doi:10.1094/pdis.2000.84.7.810b
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  Tomato yellow leaf curl virus (TYLCV) causes a serious disease of tomato in many countries throughout the world. Preliminary reports suggested that TYLC disease was present in 1997 in South Africa. In 1998 140 ha of tomato fields in the Onderberg area were assessed for possible presence of TYLCV. Symptoms like those caused by TYLCV isolates in Israel were observed in most fields, and disease incidence ranged from
• Bird, J., Brown, J. K., & Idris, A. M. (1999). First Report of a Bean-Infecting Begomovirus from Macroptilium lathyroides in Puerto Rico That Is Distinct from Bean Golden Mosaic Virus.. Plant disease, 83(11), 1071. doi:10.1094/pdis.1999.83.11.1071c
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  Bean golden mosaic begomovirus (BGMV) was long suspected to cause bright yellow mosaic symptoms in Macroptilium lathyroides (L.), a weed common to Puerto Rico. M. lathyroides plants exhibiting bright yellow mosaic symptoms were collected from Puerto Rico during 1994 to 1999, and the biotic and molecular characteristics of the suspect begomovirus were determined. Symptoms in M. lathyroides, indistinguishable from those observed in field-infected plants, were reproducible by whitefly transmission (Bemisia tabaci type B) and biolistic inoculation of leaf extracts (1). In bean, Phaseolus vulgaris (L.) 'Topcrop,' the M. lathyroides virus caused green-yellow mosaic foliar symptoms and stunting, reminiscent of symptoms caused by BGMV from Puerto Rico (BGMV-PR). However, biolistic- or whitefly-mediated inoculation of M. lathyroides with BGMV-PR resulted in no discernible infection. Sequence analysis (2) of the coat protein (CP) gene (AF176092) and common region of the A (CR-A) (AF176093) and B (CR-B) (AF176094) components of the virus from M. lathyroides indicated that these sequences shared only 77.3 to 79.3% and 62.4 to 68.8% identity, respectively, with BGMV from the Dominican Republic, Honduras, Guatemala, Jamaica (JAM), and PR. Alignment of the M. lathyroides virus CP sequence with other well-studied begomoviruses indicate its closest relative is BGMV-PR (82%) and that it shares less than 73% identity with partial CP sequences of Macroptilium golden mosaic virus-JAM (AF089839, AF089840). The directly repeated CR sequences of the M. lathyroides virus, putatively involved in AC1 binding, are TGGTGACTGGTG and are distinct from TGGAGACTGGAG, the analogous direct repeat in BGMV-PR. We provisionally designate the new, previously undescribed begomovirus species from M. lathyroides, Macroptilium mosaic virus (MaMV). Results indicate MaMV-PR and BGMV are distinct, bean-infecting begomoviruses from the Caribbean and that MaMV-PR may pose a new threat to bean production, particularly where the type B vector is established. References: (1) J. K. Brown and R. Ryan. Phytopathology 81:1217, 1991; (2) A. M. Idris and J. K. Brown. Phytopathology 88:648, 1998.
• Brown, J. K., Idris, A. M., & Lee, S. H. (1999). First Report of Chino del Tomate and Pepper Hausteco Geminivurses in Greenhouse-Grown Tomato in Sonora, Mexico.. Plant disease, 83(4), 396. doi:10.1094/pdis.1999.83.4.396b
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  Tomato plants grown in commercial greenhouses in Sonora, Mexico, developed either yellow mosaic, leaf curling, and stunting (phenotype 1; 20 to 35%) or chlorosis and a feathery appearance of leaves (phenotype 2; 15 to 25%) in December 1997 and again in October 1998. Polymerase chain reaction (PCR) with diagnostic primers (prAV324 and prAC889) that amplify an approximately 576-bp fragment of the coat protein (CP) gene of whitefly-transmitted geminiviruses indicated the presence of a begomovirus. Biolistic inoculation of tomato seedlings with RNase-treated extracts of three symptomatic tomato samples, each, resulted in reproduction of disease symptoms. With PCR primers prAV2644 and prAC1154 (1), the entire CP (approximately 776 bp) and its flanking sequences were amplified from extracts of symptomatic tomato, and amplicons were cloned and sequenced. Comparisons of a minimum of three CP gene sequences from each phenotype revealed the presence of at least two begomoviruses. The phenotype 1-associated CP gene shared 92.6, 86.2, and 85.3% identity with the CP sequence of chino del tomate (CdTV) [AF106936], tomato mottle, and abutilon mosaic geminiviruses, respectively. The CP sequence associated with phenotype 2 was 94.6, 77.1, and 77.1% identical to pepper hausteco (PHV) [X70418], bean golden mosaic-Guatemala (BGMV-GU), and Texas pepper (TPV) gem-iniviruses, respectively. Previously, CdTV was reported from tomato in Chiapas, Morelos, Sinaloa, and Tamaulipas, Mexico, while PHV has been identified in Guanajuato, Quintana Roo, Sinaloa, and Tamaulipas, Mexico, and in Texas (2). This is the first report of CdTV-like (>92% identity) and PHV-like (>94% identity) geminiviruses associated with greenhouse-grown tomatoes in Sonora, Mexico. References: (1) A. M. Idris and J. K. Brown. Phytopathology 88:648, 1998; (2) I. Torres-Pacheco et al. Phytopathology 86:1186, 1996.
• Brown, J. K., Idris, A. M., Rivas-platero, G., & Torres-jerez, I. (1999). First Report of Sinaloa Tomato Leaf Curl Geminivirus in Costa Rica.. Plant disease, 83(3), 303. doi:10.1094/pdis.1999.83.3.303c
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  In October 1998, geminivirus-like symptoms were widespread in tomato plantings near Turrialba, Costa Rica. Isolates from several fields were experimentally transmitted to tomato seedlings with whiteflies from a Bemisia tabaci (Genn.) colony maintained at CATIE, which resulted in interveinal chlorosis and leaf curling symptoms indistinguishable from those observed in the field. Total DNA was extracted from leaves of 16 of these experimentally inoculated plants and assayed by polymerase chain reaction (PCR) for the presence of begomovirus DNA with the degenerate primers AV324 and AC889 (2) to amplify the core region of the coat protein gene (core Cp). PCR yielded the expected size core Cp fragment (576 bp) from 16 of 16 samples. The core Cp fragments of six samples were cloned and sequenced. A comparison of the core Cp sequences with reference begomovirus sequences indicated all Costa Rican isolates were >95% identical to Sinaloa tomato leaf curl geminivirus reported in 1994 from Sinaloa, Mexico (STLCV-SINALOA). Virus identity was confirmed by multiple sequence alignments of the viral coat protein gene (Cp) and the common region (CR) sequences of A and B components (CR-A and CR-B), respectively, with analogous reference begomovirus sequences. Cp and CRs were obtained by PCR, and amplicons were cloned and sequenced as described (1). The Cp open reading frame (ORF; 756 nucleotides) (AF110515) identified within the A component amplicon shared 92.9% sequence identity with STLCV-SINALOA Cp (AF040635). The CR sequences of the A (AF1150516) and B (AF110517) components (163 nucleotides) shared 98.2% sequence identity with each other, suggesting that they were amplified from the cognate A and B components of the same virus. Further, the CR-A and CR-B components contained the same putative Rep binding site, TGGGGT-AA-TGGGGT, which was also identical to that of STLCV-SINALOA. The mean percent divergences between viral Cp and CR amplicons (n = 6+) ranged from 98 to 100%. Collectively, STLCV-like symptoms in tomato, >92% identity between viral Cp sequences, and identical CR iterons indicate that the Costa Rican tomato virus is STLCV, or a closely related strain. This is the first report of an STLCV-like begomovirus in tomato in Costa Rica (STLCV-CR). References: (1) A. M. Idris and J. K. Brown. Phytopathology 88:648, 1998. (2) S. D. Wyatt and J. K. Brown. Phytopathology 86:1288, 1996.
• Brown, J. K., Ostrow, K. M., Idris, A. M., & Stenger, D. C. (1999). Biotic, molecular, and phylogenetic characterization of bean calico mosaic virus, a distinct Begomovirus species with affiliation in the squash leaf curl virus cluster. Phytopathology, 89(4), 273-280.
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  PMID: 18944770;Abstract: Bean calico mosaic virus (BCMoV), a whitefly-transmitted geminivirus from Sonora, Mexico, was purified, and the genome components were cloned and sequenced. Purified viral fractions and cloned genome components were infectious by biolistic inoculation to bean, completing Koch's postulates for both. The B biotype of the whitefly Bemisia tabaci efficiently transmitted both native virus and progeny virus derived from cloned DNA inoculum. Host ranges of native virus and of progeny virus derived from cloned DNA were identical based upon whitefly and biolistic mediated transmission, respectively. BCMoV has a relatively wide experimental host range among begomoviruses known to infect bean, encompassing genera and species within the Fabaceae, Malvaceae, and Solanaceae. BCMoV has a bipartite genome, as do other New World begomoviruses. BCMoV DNA-A shared highest nucleotide sequence identities with squash leaf curl virus-E strain (SLCV-E) and cabbage leaf curl virus (CaLCV) at 80.1 and 80.7%, respectively. BCMoV DNA-B shared highest nucleotide sequence identity With SLCV-E at 70.7%. The common region (CR) sequences of BCMoV and SLCV-E are 73 to 76% identical; however, modular cis-acting elements within the CR involved in replication origin function and recognition are 100% conserved. Phylogenetic analysis indicated that BCMoV DNA-A shares a most recent common ancestor with the DNA-A of two viruses that also occur in the Sonoran Desert, SLCV-E and Texas pepper virus (TPV-TAM), and CaLCV from Florida. In contrast, a phylogenetic analysis indicated that BCMoV DNA-B shares a most recent common ancestor with SLCV-E; whereas DNA-B of CaLCV clustered in a separate clade with pepper hausteco virus. Collectively, biological and molecular characteristics indicate that BCMoV is a distinct begomovirus species with the northernmost distribution of any begomovirus isolated from bean in the Americas. Furthermore, the phylogenetic relationships of begomovirus cognate components are not necessarily identical, suggesting that DNA-A and DNA-B of some begomoviruses may have different evolutionary histories.
• Brown, J. K., Ostrow, K. M., Idris, A. M., & Stenger, D. C. (1999). Biotic, molecular, and phylogenetic characterization of bean calico mosaic virus, a distinct Begomovirus species with affiliation in the squash leaf curl virus cluster. Phytopathology, 89(Issue 4). doi:10.1094/phyto.1999.89.4.273
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  Bean calico mosaic virus (BCMoV), a whitefly-transmitted geminivirus from Sonora, Mexico, was purified, and the genome components were cloned and sequenced. Purified viral fractions and cloned genome components were infectious by biolistic inoculation to bean, completing Koch's postulates for both. The B biotype of the whitefly Bemisia tabaci efficiently transmitted both native virus and progeny virus derived from cloned DNA inoculum. Host ranges of native virus and of progeny virus derived from cloned DNA were identical based upon whitefly and biolistic mediated transmission, respectively. BCMoV has a relatively wide experimental host range among begomoviruses known to infect bean, encompassing genera and species within the Fabaceae, Malvaceae, and Solanaceae. BCMoV has a bipartite genome, as do other New World begomoviruses. BCMoV DNA-A shared highest nucleotide sequence identities with squash leaf curl virus-E strain (SLCV-E) and cabbage leaf curl virus (CaLCV) at 80.1 and 80.7%, respectively. BCMoV DNA-B shared highest nucleotide sequence identity With SLCV-E at 70.7%. The common region (CR) sequences of BCMoV and SLCV-E are 73 to 76% identical; however, modular cis-acting elements within the CR involved in replication origin function and recognition are 100% conserved. Phylogenetic analysis indicated that BCMoV DNA-A shares a most recent common ancestor with the DNA-A of two viruses that also occur in the Sonoran Desert, SLCV-E and Texas pepper virus (TPV-TAM), and CaLCV from Florida. In contrast, a phylogenetic analysis indicated that BCMoV DNA-B shares a most recent common ancestor with SLCV-E; whereas DNA-B of CaLCV clustered in a separate clade with pepper hausteco virus. Collectively, biological and molecular characteristics indicate that BCMoV is a distinct begomovirus species with the northernmost distribution of any begomovirus isolated from bean in the Americas. Furthermore, the phylogenetic relationships of begomovirus cognate components are not necessarily identical, suggesting that DNA-A and DNA-B of some begomoviruses may have different evolutionary histories.
• Frohlich, D. R., Torres-Jerez, I., Bedford, I. D., Markham, P. G., & Brown, J. K. (1999). A phylogeographical analysis of the Bemisia tabaci species complex based on mitochondrial DNA markers. Molecular Ecology, 8(10), 1683-1691.
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  Abstract: Mitochondrial 16S (~550 bp) and cytochrome oxidase I (COI) (~700 bp) sequences were utilized as markers to reconstruct a phylogeography for representative populations or biotypes of Bemisia tabaci. 16S sequences exhibited less divergence than COI sequences. Of the 429 characters examined for COI sequences, 185 sites were invariant, 244 were variable and 108 were informative. COI sequence identities yielded distances ranging from less than 1% to greater than 17%. Whitefly 16S sequences of 456 characters were analysed which consisted of 298 invariant sites, 158 variable sites and 53 informative sites. Phylogenetic analyses conducted by maximum parsimony, maximum-likelihood and neighbour-joining methods yielded almost identical phylogenetic reconstructions of trees that separated whiteflies based on geographical origin. The 16S and COI sequence data indicate that the B-biotype originated in the Old World (Europe, Asia and Africa) and is most closely related to B-like variants from Israel and Yemen, with the next closest relative being a biotype from Sudan. These data confirm the biochemical, genetic and behavioural polymorphisms described previously for B. tabaci. The consideration of all global variants of B. tabaci as a highly cryptic group of sibling species is argued.
• Frohlich, D. R., Torres-Jerez, I., Bedford, I. D., Markham, P. G., & Brown, J. K. (1999). A phylogeographical analysis of the Bemisia tabaci species complex based on mitochondrial DNA markers. Molecular Ecology, 8(Issue 10). doi:10.1046/j.1365-294x.1999.00754.x
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  Mitochondrial 16S (~550 bp) and cytochrome oxidase I (COI) (~700 bp) sequences were utilized as markers to reconstruct a phylogeography for representative populations or biotypes of Bemisia tabaci. 16S sequences exhibited less divergence than COI sequences. Of the 429 characters examined for COI sequences, 185 sites were invariant, 244 were variable and 108 were informative. COI sequence identities yielded distances ranging from less than 1% to greater than 17%. Whitefly 16S sequences of 456 characters were analysed which consisted of 298 invariant sites, 158 variable sites and 53 informative sites. Phylogenetic analyses conducted by maximum parsimony, maximum-likelihood and neighbour-joining methods yielded almost identical phylogenetic reconstructions of trees that separated whiteflies based on geographical origin. The 16S and COI sequence data indicate that the B-biotype originated in the Old World (Europe, Asia and Africa) and is most closely related to B-like variants from Israel and Yemen, with the next closest relative being a biotype from Sudan. These data confirm the biochemical, genetic and behavioural polymorphisms described previously for B. tabaci. The consideration of all global variants of B. tabaci as a highly cryptic group of sibling species is argued.
• Paximadis, M., Idris, A. M., Torres-Jerez, I., Villarreal, A., Rey, M. E., & Brown, J. K. (1999). Characterization of tobacco geminiviruses in the old and new world. Archives of Virology, 144(4), 703-717.
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  PMID: 10365162;Abstract: Biological differences and molecular variability between six phenotypically distinct tobacco-infecting geminivirus isolates from southern Africa (Zimbabwe) and Mexico were investigated. Host range studies conducted with tobacco virus isolates ZIM H from Zimbabwe and MEX 15 and MEX 32 from Mexico indicated all had narrow host ranges restricted to the Solanaceae. Alignment of coat protein gene (CP) and common region (CR) sequences obtained by PCR, and phylogenetic analysis of the CP sequences indicated Zimbabwean isolates were distantly related to those from Mexico and that geographically proximal isolates shared their closest affinities with Old and New World geminiviruses, respectively. Zimbabwean isolates formed a distinct cluster of closely related variants (>98% sequence identity) of the same species, while MEX 15 segregated independently from MEX 32, the former constituting a distinct species among New World geminiviruses, and the latter being a variant, Texas pepper virus-Chiapas isolate (TPV-CPS) with 95% sequence identity to TPV-TAM. Results collectively indicated a geographic basis for phylogenetic relationships rather than a specific affiliation with tobacco as a natural host. MEX 15 is provisionally described as a new begomovirus, tobacco apical stunt virus, TbASV, whose closest CP relative is cabbage leaf curl virus, and ZIM isolates are provisionally designated as tobacco leaf curl virus, TbLCV-ZIM, a new Eastern Hemisphere begomovirus, which has as its closest relative, chayote mosaic virus from Nigeria.
• Paximadis, M., Idris, A. M., Torres-Jerez, I., Villarreal, A., Rey, M. E., & Brown, J. K. (1999). Characterization of tobacco geminiviruses in the old and new world. Archives of Virology, 144(Issue 4). doi:10.1007/s007050050537
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  Biological differences and molecular variability between six phenotypically distinct tobacco-infecting geminivirus isolates from southern Africa (Zimbabwe) and Mexico were investigated. Host range studies conducted with tobacco virus isolates ZIM H from Zimbabwe and MEX 15 and MEX 32 from Mexico indicated all had narrow host ranges restricted to the Solanaceae. Alignment of coat protein gene (CP) and common region (CR) sequences obtained by PCR, and phylogenetic analysis of the CP sequences indicated Zimbabwean isolates were distantly related to those from Mexico and that geographically proximal isolates shared their closest affinities with Old and New World geminiviruses, respectively. Zimbabwean isolates formed a distinct cluster of closely related variants (>98% sequence identity) of the same species, while MEX 15 segregated independently from MEX 32, the former constituting a distinct species among New World geminiviruses, and the latter being a variant, Texas pepper virus-Chiapas isolate (TPV-CPS) with 95% sequence identity to TPV-TAM. Results collectively indicated a geographic basis for phylogenetic relationships rather than a specific affiliation with tobacco as a natural host. MEX 15 is provisionally described as a new begomovirus, tobacco apical stunt virus, TbASV, whose closest CP relative is cabbage leaf curl virus, and ZIM isolates are provisionally designated as tobacco leaf curl virus, TbLCV-ZIM, a new Eastern Hemisphere begomovirus, which has as its closest relative, chayote mosaic virus from Nigeria.
• Rosell, R. C., Torres-Jerez, I., & Brown, J. K. (1999). Tracing the geminivirus-whitefly transmission pathway by polymerase chain reaction in whitefly extracts, saliva, hemolymph, and honeydew. Phytopathology, 89(3), 239-246.
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  PMID: 18944765;Abstract: A membrane feeding system and polymerase chain reaction (PCR) were used to track squash leaf curl virus (SLCV) DNA in whole whitefly body extracts and in saliva, honeydew, and hemolymph of its whitefly vector, Bemisia tabaci, and a whitefly nonvector, Trialeurodes vaporariorum. SLCV ingestion was monitored by PCR in whiteflies that were given acquisition access periods (AAPs) ranging from 0.5 to 96 h on virus-infected plants. SLCV detection by PCR in whole body extracts was considered reflective of virus ingestion. As whiteflies were given longer AAPs, the number of whiteflies that ingested SLCV increased. SLCV DNA was detected in honeydew of vector and nonvector whiteflies, indicating that virions, viral DNA, or both passed unimpeded through the digestive system. SLCV DNA was detected in saliva and hemolymph of B. tabaci, but not in these fractions from nonvector whiteflies, despite virus ingestion by both. Although vector and nonvector whiteflies both ingested SLCV, only in the vector, B. tabaci, did virus cross the gut barrier, enter the hemolymph, or pass into the salivary system. These results suggest that digestive epithelia of nonvector whiteflies did not permit SLCV passage from the gut to hemocoel, whereas virus effectively crossed the analogous gut barrier in vector whiteflies.
• Rosell, R. C., Torres-Jerez, I., & Brown, J. K. (1999). Tracing the geminivirus-whitefly transmission pathway by polymerase chain reaction in whitefly extracts, saliva, hemolymph, and honeydew. Phytopathology, 89(Issue 3). doi:10.1094/phyto.1999.89.3.239
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  A membrane feeding system and polymerase chain reaction (PCR) were used to track squash leaf curl virus (SLCV) DNA in whole whitefly body extracts and in saliva, honeydew, and hemolymph of its whitefly vector, Bemisia tabaci, and a whitefly nonvector, Trialeurodes vaporariorum. SLCV ingestion was monitored by PCR in whiteflies that were given acquisition access periods (AAPs) ranging from 0.5 to 96 h on virus-infected plants. SLCV detection by PCR in whole body extracts was considered reflective of virus ingestion. As whiteflies were given longer AAPs, the number of whiteflies that ingested SLCV increased. SLCV DNA was detected in honeydew of vector and nonvector whiteflies, indicating that virions, viral DNA, or both passed unimpeded through the digestive system. SLCV DNA was detected in saliva and hemolymph of B. tabaci, but not in these fractions from nonvector whiteflies, despite virus ingestion by both. Although vector and nonvector whiteflies both ingested SLCV, only in the vector, B. tabaci, did virus cross the gut barrier, enter the hemolymph, or pass into the salivary system. These results suggest that digestive epithelia of nonvector whiteflies did not permit SLCV passage from the gut to hemocoel, whereas virus effectively crossed the analogous gut barrier in vector whiteflies.
• Anthony, N. M., Brown, J. K., Feyereisen, R., & Ffrench-Constant, R. (1998). Diagnosis and characterization of insecticide-insensitive acetylcholinesterase in three populations of the sweetpotato whitefly bemisia tabaci. Pesticide Science, 52(1), 39-46.
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  Abstract: A biochemical approach was used to characterize acetylcholinesterase (ACHE) insecticide insensitivity in several sweetpotato whitefly (Bemisia tabaci; SPW) populations. Discriminating doses of insecticide were established to differentiate between sensitive and insensitive SPW strains and to genotype individual whitefly. This technique was then used to examine the frequency of insensitive AChE alleles in several SPW populations and to isolate a line homozygous for insensitive AChE from a heterogenous B-type population. Inheritance of putative altered AChE genotypes was consistent with the proposed haplo-diploid status of B. tabaci. This biochemical diagnostic was also employed to determine the role of insensitive AChE in the observed resistance profiles of several laboratory populations subjected to different selection regimes. In keeping with previous studies on insecticide resistance in SPW, resistance does not appear to be uniquely associated with the B-type but rather with SPW populations found in crop systems.
• Brown, J. K. (1998). Global diversity and distribution of whitefly-transmitted geminiviruses of cotton. Proceedings of the 1998 beltwide cotton conferences, San Diego, CA, USA, January 5-9 1999, 155-161.
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  Abstract: Geminivrus diseases of cotton are on the rise, worldwide, yet few have been studied in adequate detail to permit the implementation of rational approaches to disease control. The rising costs of managing the whitefly vector, coupled to substantial losses caused by geminivirus-incited diseases now hinder cotton production by requiring inputs that are beyond economic feasibility. The requirement for geminivirus disease resistance in numerous cotton cultivars and multiple, diverse geographic cotton production areas of the world presents a new and unique challenge. To meet this need, baseline information concerning the identity, the distribution, and the relevant characteristics of cotton-infecting geminiviruses and virus strains, thereof, are now required. This study addresses this problem by attaining and applying molecular sequence analysis to key regions of the genomes of cotton-infecting geminivirus collected from cotton growing regions of the world. Specifically, we are examining the sequence similarities of the conserved the coat protein or AV1 gene, and the similarities and particular features associated with diagnostic nucleotides found in the LIR/CR that are involved in regulating essential aspects of the disease cycle. This effort represents the first cataloging and mapping of geminivirus identity and distribution, and the first investigation of the breadth of germiniviral relationships, or the 'diversity' of geminiviruses of cotton, worldwide. It seeks to understand relationships between cotton-infecting geminiviruses and of these viruses and other well-characterized or 'reference' geminiviruses from diverse crop and weed species. This data base of molecular and biotic information will serve as the cornerstone for the rational selection of virus species and strains toward developing cotton cultivars with resistance customized to protect against disease caused by geminiviruses relevant to the production area. This approach will also permit the first precise evaluation of the breadth of disease resistance in a cultivar by permitting challenge-inoculation with narrowly and broadly divergent virus genotypes, thereby providing both a predictive capacity for sustainability of disease resistance and a safeguard to achieve long term protection against indigenous and introduced, exotic geminiviruses of cotton.
• Brown, J. K. (1998). Global diversity and distribution of whitefly-transmitted geminiviruses of cotton. Proceedings of the 1998 beltwide cotton conferences, San Diego, CA, USA, January 5-9 1999.
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  Geminivrus diseases of cotton are on the rise, worldwide, yet few have been studied in adequate detail to permit the implementation of rational approaches to disease control. The rising costs of managing the whitefly vector, coupled to substantial losses caused by geminivirus-incited diseases now hinder cotton production by requiring inputs that are beyond economic feasibility. The requirement for geminivirus disease resistance in numerous cotton cultivars and multiple, diverse geographic cotton production areas of the world presents a new and unique challenge. To meet this need, baseline information concerning the identity, the distribution, and the relevant characteristics of cotton-infecting geminiviruses and virus strains, thereof, are now required. This study addresses this problem by attaining and applying molecular sequence analysis to key regions of the genomes of cotton-infecting geminivirus collected from cotton growing regions of the world. Specifically, we are examining the sequence similarities of the conserved the coat protein or AV1 gene, and the similarities and particular features associated with diagnostic nucleotides found in the LIR/CR that are involved in regulating essential aspects of the disease cycle. This effort represents the first cataloging and mapping of geminivirus identity and distribution, and the first investigation of the breadth of germiniviral relationships, or the 'diversity' of geminiviruses of cotton, worldwide. It seeks to understand relationships between cotton-infecting geminiviruses and of these viruses and other well-characterized or 'reference' geminiviruses from diverse crop and weed species. This data base of molecular and biotic information will serve as the cornerstone for the rational selection of virus species and strains toward developing cotton cultivars with resistance customized to protect against disease caused by geminiviruses relevant to the production area. This approach will also permit the first precise evaluation of the breadth of disease resistance in a cultivar by permitting challenge-inoculation with narrowly and broadly divergent virus genotypes, thereby providing both a predictive capacity for sustainability of disease resistance and a safeguard to achieve long term protection against indigenous and introduced, exotic geminiviruses of cotton.
• Brown, J. K., & O'hara, R. B. (1998). Movement of barley powdery mildew within field plots. Plant Pathology, 47(4), 394-400. doi:10.1046/j.1365-3059.1998.00270.x
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  Movement of barley powdery mildew (caused by Erysiphe graminis f.sp. hordei) within fields was investigated by sowing the barley cultivars Tyra and Jupiter side by side in two field plots, and trapping spores along transects within the plots. The trapped spores were tested for virulence on the two cultivars. The epidemic on Tyra developed quickly, and a gradient in the proportion of spores with virulence on Tyra was detected in the Jupiter half-plots. In the Jupiter half-plots, the epidemic was much less severe; and no mildew could be found in one plot. Movement of spores from one half of the plot to the other usually declined steeply in the first 4 m from the boundary, and was not detectable beyond 12 m. There were exceptions where the gradient was much shallower, and these were consistent with differences in wind direction.
• Idris, A. M., & Brown, J. K. (1998). Sinaloa tomato leaf curl geminivirus: Biological and molecular evidence for a new subgroup III virus. Phytopathology, 88(7), 648-657.
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  PMID: 18944936;Abstract: The biological and molecular properties of Sinaloa tomato leaf curl virus (STLCV) were investigated in line with the hypothesis that STLCV is a previously uncharacterized, whitefly-transmitted geminivirus from North America. STLCV causes yellow leaf curl symptoms in tomato and yellow-green foliar mottle in pepper. Five species belonging to two plant families were STLCV experimental hosts. STLCV had a persistent relationship with its whitefly vector, Bemisia tabaci. Polymerase chain reaction fragments of STLCV common region (CR) sequences of the A or B genomic components and the vital coat protein gene (AVI) were molecularly cloned and sequenced. The STLCV A- and B-component CR sequences (174 nucleotides each) shared 97.9% identity and contained identical cis elements putatively involved in transcriptional regulation and an origin of replication (the AC cleavage site within the loop of the hairpin structure and two direct repeat sequences thought to constitute the Rep binding motif), which collectively are diagnostic for subgroup III geminiviruses. The STLCV CR sequence shared 23.1 to 77.6% identity with CR sequences of representative geminiviridae, indicating the STLCV CR sequence is unique. Molecular phylogenetic analysis of CR or AVI sequences of STLCV and the respective sequences of 31 familial members supported the placement of STLCV as a unique bipartite, subgroup III virus most closely related to other viruses from the Western Hemisphere. STLCV is provisionally described as a new species within the genus Begomovirus, family Geminiviridae.
• Idris, A. M., & Brown, J. K. (1998). Sinaloa tomato leaf curl geminivirus: Biological and molecular evidence for a new subgroup III virus. Phytopathology, 88(Issue 7). doi:10.1094/phyto.1998.88.7.648
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  The biological and molecular properties of Sinaloa tomato leaf curl virus (STLCV) were investigated in line with the hypothesis that STLCV is a previously uncharacterized, whitefly-transmitted geminivirus from North America. STLCV causes yellow leaf curl symptoms in tomato and yellow-green foliar mottle in pepper. Five species belonging to two plant families were STLCV experimental hosts. STLCV had a persistent relationship with its whitefly vector, Bemisia tabaci. Polymerase chain reaction fragments of STLCV common region (CR) sequences of the A or B genomic components and the vital coat protein gene (AVI) were molecularly cloned and sequenced. The STLCV A- and B-component CR sequences (174 nucleotides each) shared 97.9% identity and contained identical cis elements putatively involved in transcriptional regulation and an origin of replication (the AC cleavage site within the loop of the hairpin structure and two direct repeat sequences thought to constitute the Rep binding motif), which collectively are diagnostic for subgroup III geminiviruses. The STLCV CR sequence shared 23.1 to 77.6% identity with CR sequences of representative geminiviridae, indicating the STLCV CR sequence is unique. Molecular phylogenetic analysis of CR or AVI sequences of STLCV and the respective sequences of 31 familial members supported the placement of STLCV as a unique bipartite, subgroup III virus most closely related to other viruses from the Western Hemisphere. STLCV is provisionally described as a new species within the genus Begomovirus, family Geminiviridae.
• Salvucci, M. E., Rosell, R. C., & Brown, J. K. (1998). Uptake and metabolism of leaf proteins by the silverleaf whitefly. Archives of Insect Biochemistry and Physiology, 39(4), 155-165.
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  Abstract: To determine if plant proteins can be ingested and metabolized by the silverleaf whitefly, whiteflies were fed artificial diets containing either 35S-labeled cotton leaf proteins or a fluorescently labeled recombinant leaf protein. Confocal microscopy showed that whiteflies contained fluorescence throughout their digestive tracts and in their honeydew after feeding on fluorescently labeled protein. On diets containing radiolabeled protein, 35S was ingested and either excreted as amino acids or retained in the body in protein and free amino acids. The profiles of radiolabeled whitefly polypeptides were similar for whiteflies feeding on labeled protein and labeled amino acids. Thus, whiteflies can ingest plant proteins, degrade them to free amino acids, and either excrete the amino acids or use them for de novo protein synthesis. Uptake and metabolism of radiolabel occurred when whiteflies fed on 35S-labeled leaves. Honeydew from these insects contained a small amount of labeled protein. The label in honeydew protein was primarily associated with a 22.4 kDa polypeptide. This polypeptide co-migrated with a labeled whitefly polypeptide and its synthesis was inhibited by cycloheximide. The identity and func-tion of this protein are unknown. © 1998 Wiley-Liss, Inc.
• Salvucci, M. E., Rosell, R. C., & Brown, J. K. (1998). Uptake and metabolism of leaf proteins by the silverleaf whitefly. Archives of Insect Biochemistry and Physiology, 39(Issue 4). doi:10.1002/(sici)1520-6327(1998)39:4<155::aid-arch3>3.0.co;2-%23
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  To determine if plant proteins can be ingested and metabolized by the silverleaf whitefly, whiteflies were fed artificial diets containing either 35S-labeled cotton leaf proteins or a fluorescently labeled recombinant leaf protein. Confocal microscopy showed that whiteflies contained fluorescence throughout their digestive tracts and in their honeydew after feeding on fluorescently labeled protein. On diets containing radiolabeled protein, 35S was ingested and either excreted as amino acids or retained in the body in protein and free amino acids. The profiles of radiolabeled whitefly polypeptides were similar for whiteflies feeding on labeled protein and labeled amino acids. Thus, whiteflies can ingest plant proteins, degrade them to free amino acids, and either excrete the amino acids or use them for de novo protein synthesis. Uptake and metabolism of radiolabel occurred when whiteflies fed on 35S-labeled leaves. Honeydew from these insects contained a small amount of labeled protein. The label in honeydew protein was primarily associated with a 22.4 kDa polypeptide. This polypeptide co-migrated with a labeled whitefly polypeptide and its synthesis was inhibited by cycloheximide. The identity and func-tion of this protein are unknown. © 1998 Wiley-Liss, Inc.
• Rosell, R. C., Bedford, I. D., Frohlich, D. R., Gill, R. J., Brown, J. K., & Markham, P. G. (1997). Analysis of morphological variation in distinct populations of Bemisia tabaci (Homoptera: Aleyrodidae). Annals of the Entomological Society of America, 90(5), 575-589.
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  Abstract: Morphological characters of whiteflies, Bemisia spp., from 17 populations from disparate locations worldwide were compared. Historically, characters of 4th instars (pupae) are used for separating Bemisia spp. We assessed variability in the following characters of the 4th instar: anterior submarginal setae, anterior and posterior was fringes, dorsal setae, posterior submarginal setae, caudal setae, and tracheal folds. Anterior submarginal setae 4 (ASMS 4) were generally, but not always, absent in B. argentifolli Bellows & Perring and B biotype populations, and in most non-A/ non-B biotype (E, K, L, P, and Q). However, ASMS 4 were found in A biotype, in the N biotype, and in B. hancocki. Dorsal setal pair 4 was absent in most populations, and the lenghts of dorsal setal paris 1, 2, 3, 5, and 6 varied on individuals from several populations. Anterior was fringes were highly variable in length and width in all populations. With the exception of the Nepal (P biotype) population, posterior was fringes extended beyond the borders of the caudal setae in all individuals examined. Although posterior submarginal setal pair 5 (PSMS 5) was short in most individuals examined, these setae were elongated in a few individuals from 5 populations. Phylogenetic analysis did not resolve most-parsimonious trees. Our obsrvations indicate that morphological characters of pupae are not useful alone for classifying individuals from B. tabaci or B. argentifolii populations.
• Rosell, R. C., Bedford, I. D., Frohlich, D. R., Gill, R. J., Brown, J. K., & Markham, P. G. (1997). Analysis of morphological variation in distinct populations of Bemisia tabaci (Homoptera: Aleyrodidae). Annals of the Entomological Society of America, 90(Issue 5). doi:10.1093/aesa/90.5.575
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  Morphological characters of whiteflies, Bemisia spp., from 17 populations from disparate locations worldwide were compared. Historically, characters of 4th instars (pupae) are used for separating Bemisia spp. We assessed variability in the following characters of the 4th instar: anterior submarginal setae, anterior and posterior was fringes, dorsal setae, posterior submarginal setae, caudal setae, and tracheal folds. Anterior submarginal setae 4 (ASMS 4) were generally, but not always, absent in B. argentifolli Bellows & Perring and B biotype populations, and in most non-A/ non-B biotype (E, K, L, P, and Q). However, ASMS 4 were found in A biotype, in the N biotype, and in B. hancocki. Dorsal setal pair 4 was absent in most populations, and the lenghts of dorsal setal paris 1, 2, 3, 5, and 6 varied on individuals from several populations. Anterior was fringes were highly variable in length and width in all populations. With the exception of the Nepal (P biotype) population, posterior was fringes extended beyond the borders of the caudal setae in all individuals examined. Although posterior submarginal setal pair 5 (PSMS 5) was short in most individuals examined, these setae were elongated in a few individuals from 5 populations. Phylogenetic analysis did not resolve most-parsimonious trees. Our obsrvations indicate that morphological characters of pupae are not useful alone for classifying individuals from B. tabaci or B. argentifolii populations.
• Boulaire, S. L., Brown, J. K., & Evans, N. (1996). Genetics of responses to morpholine-type fungicides and of avirulences in Erysiphe graminis f. sp. hordei. European Journal of Plant Pathology, 102(5), 479-490. doi:10.1007/bf01877142
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  The genetics of the responses of the barley powdery mildew pathogen,Erysiphe graminis f.sp.hordei, to three morpholine-type fungicides were studied. Resistances to a phenylpropylamine fungicide, fenpropidin, and to a morpholine, fenpropimorph, co-segregated in crosses of a sensitive isolate, DH14, with each of two resistant ones, CC151 and CC152. In the cross CC151×DH14, the results were consistent with resistance to both fungicides being controlled by a single gene, at a locus namedFenl. In the other cross, CC152×DH14, the genetics of resistance were more complicated; the data were consistent with the segregation of two complementary, unlinked genes which each conferred resistance to both fungicides. Fenpropidin-resistant progeny of CC151×DH14 were significantly more resistant to fenpropimorph than were fenpropidin-resistant progeny of CCI 52×DH14, although the resistant progeny of the two crosses did not differ significantly in their level of fenpropidin resistance. Fenpropidin-resistant progeny of CC151×DH14 were significantly more resistant to another morpholine, tridemorph, than were fenpropidin-sensitive progeny, but this was not the case for CC152×DH14. Resistance to triadimenol, a C14 demethylation-inhibitor (DMI) fungicide, segregated in both crosses. Triadimenol resistance appeared to be controlled by one gene in each cross and was not associated with morpholine resistance. CC151×DH14 also segregated for eight avirulence genes. Two of these matched theMla6 resistance, while one gene matched a previously unknown resistance in a Pallas near-isogenic line, P17, which also carries a known resistance gene,Mlk. Fenl was not significantly linked to the triadimenol resistance gene,Tdl(a), or to any of the eight avirulence genes.Avra61, Avra12,AvrLa,Avrp17 andTdl(a) were linked, as wereAvra10 andAvrk.
• Boyd, L. A., Brown, J. K., Foster, E. M., & Smith, P. H. (1996). The early development of Erysiphe pisi on Pisum sativum L.. Plant Pathology, 45(2), 302-309. doi:10.1046/j.1365-3059.1996.d01-111.x
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  Erysiphe pisi, the powdery mildew pathogen of Pisum sativum, followed a developmental sequence that allowed the identification of 10 distinct growth stages (GS) over 30 h following inoculation. The growth stages were ungerminated conidia (GS1), germinated conidia, having produced a germ tube (GS2), germlings where the germ tube had forked (GS3), germlings with a multi-lobed germ tube (GS4), germlings with a single hypha (GS5), germlings with two (GS6 and 7) or three (GS8 and 9) hyphae, one of which may have formed from the appressorium (GS7 and 9), and germlings with abnormally long germ tubes (GS10), which did not develop hyphae. Conidia germinated rapidly, with a quarter of conidia producing germ tubes by 2 h after inoculation (hai). Most germlings produced multi-lobed appressoria, which showed considerable variation in structure. Haustoria, although often difficult to visualize, were first seen 4 hai, and the first hyphae 14 hai, growing from the body of the conidium. Subsequent hyphae developed from both the body of the conidium and from the appressorium.
• Brown, J. K., & O'hara, R. B. (1996). Immigration of the barley mildew pathogen into field plots of barley. Plant Pathology, 45(6), 1071-1076. doi:10.1046/j.1365-3059.1996.d01-192.x
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  Immigration of the barley powdery mildew pathogen (Erysiphe graminis f.sp. hordei) into field plots of the spring barley variety Tyra (carrying the resistance allele Mla1) was investigated. Spores were trapped from the top of the plot canopies, as well as from control plots of wheat with no barley nearby. Comparison of the frequencies of virulent and avirulent single-colony isolates showed that the amount of immigration, relative to the amount of inoculum being produced within the plot, reduced very rapidly, until it could not be detected in the middle of the growing season (mid-June).
• Brown, J. K., Bird, J., Frohlich, D. R., Rosell, R. C., Bedford, I. D., & Markham, P. G. (1996). The relevance of variability within the Bemisia tabaci species complex to epidemics caused by subgroup III geminiviruses. Bemisia: 1995. Taxonomy, biology, damage, control and management, 77-89.
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  Abstract: There are measurable differences between whitefly populations from different biogeographic backgrounds. These differences influence the capacity of B. tabaci (Hemiptera: Homoptera: Aleyrodidae) populations to vector WFT geminiviruses and are seen in whitefly host range phenotypes and host preferences that affect the ability and efficiency of whitefly mediated geminivirus transmission to and from certain hosts. Also suggestive of differences between populations are variable levels of fecundity, and that females do not mate with males from (putatively) genetically distinct populations.
• Brown, J. K., Bird, J., Frohlich, D. R., Rosell, R. C., Bedford, I. D., & Markham, P. G. (1996). The relevance of variability within the Bemisia tabaci species complex to epidemics caused by subgroup III geminiviruses. Bemisia: 1995. Taxonomy, biology, damage, control and management.
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  There are measurable differences between whitefly populations from different biogeographic backgrounds. These differences influence the capacity of B. tabaci (Hemiptera: Homoptera: Aleyrodidae) populations to vector WFT geminiviruses and are seen in whitefly host range phenotypes and host preferences that affect the ability and efficiency of whitefly mediated geminivirus transmission to and from certain hosts. Also suggestive of differences between populations are variable levels of fecundity, and that females do not mate with males from (putatively) genetically distinct populations.
• Costa, H. S., Costa, H. S., Westcot, D. M., Westcot, D. M., Ullman, D. E., Ullman, D. E., Rosell, R. C., Rosell, R. C., Brown, J. K., Brown, J. K., Johnson, M. W., & Johnson, M. W. (1996). Virus-like particles in the mycetocytes of the sweetpotato whitefly, Bemisia tabaci (homoptera, aleyrodidae). Journal of Invertebrate Pathology, 67(2), 183-186.
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  PMID: 8812594;
• Costa, H. S., Costa, H. S., Westcot, D. M., Westcot, D. M., Ullman, D. E., Ullman, D. E., Rosell, R. C., Rosell, R. C., Brown, J. K., Brown, J. K., Johnson, M. W., & Johnson, M. W. (1996). Virus-like particles in the mycetocytes of the sweetpotato whitefly, Bemisia tabaci (homoptera, aleyrodidae). Journal of Invertebrate Pathology, 67(Issue 2). doi:10.1006/jipa.1996.0028
• Markham, P. G., Bedford, I. D., Liu, S., Frolich, D. F., Rosell, R., & Brown, J. K. (1996). The transmission of geminiviruses by biotypes of Bemisia tabaci (Gennadius). Bemisia: 1995. Taxonomy, biology, damage, control and management, 69-75.
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  Abstract: Thirty populations of Bemisia tabaci (Hemiptera: Homoptera: Aleyrodidae) were collected from disparate locations worldwide. Where possible, geminiviruses were collected from the same locations. The populations were characterised by chemical and biological assays to establish the biotype. Each was tested for transmission of geminiviruses. Efficiency of transmission was related to different biological characters.
• Markham, P. G., Bedford, I. D., Liu, S., Frolich, D. F., Rosell, R., & Brown, J. K. (1996). The transmission of geminiviruses by biotypes of Bemisia tabaci (Gennadius). Bemisia: 1995. Taxonomy, biology, damage, control and management.
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  Thirty populations of Bemisia tabaci (Hemiptera: Homoptera: Aleyrodidae) were collected from disparate locations worldwide. Where possible, geminiviruses were collected from the same locations. The populations were characterised by chemical and biological assays to establish the biotype. Each was tested for transmission of geminiviruses. Efficiency of transmission was related to different biological characters.
• Torres-Pacheco, I., Garzón-Tiznado, J. A., Brown, J. K., Becerra-Flora, A., & Rivera-Bustamante, R. F. (1996). Detection and distribution of geminiviruses in Mexico and the southern United States. Phytopathology, 86(11), 1186-1192.
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  Abstract: Plant samples from important horticultural areas in Mexico and the southern United States were collected during several seasons and analyzed for the presence of geminiviruses by a combination of agarose gel electrophoresis, molecular hybridization, and polymerase chain reaction amplification techniques. A general detection strategy confirmed the presence of geminiviruses in all horticultural areas of Mexico in pepper, tomato, tomatillo (Physalis ixocarpa), cucurbits, and tobacco. Specific detection procedures showed that pepper huasteco virus is widely distributed in Mexico; it was found in pepper and tomato samples in both coastal areas, as well as in central Mexico. It was also found in pepper samples from the Rio Grande Valley in southern Texas. Pepper jalapeno virus (PJV) and chino del tomate virus (CdTV) showed a more restricted distribution, although, in all cases, the viruses appeared to become more widely distributed over time. Partial DNA sequences of PJV and CdTV were also obtained. Comparative sequence analysis showed that PJV and the previously described Texas pepper geminivirus are probably strains of the same virus. The name pepper jalapeno virus is, thus, withdrawn to avoid further confusion. Similarly, CdTV showed a very high level of sequence identity with the recently described tomato leaf crumple virus (TLCrV), also suggesting that they both are strains of the same virus.
• Torres-Pacheco, I., Garzón-Tiznado, J. A., Brown, J. K., Becerra-Flora, A., & Rivera-Bustamante, R. F. (1996). Detection and distribution of geminiviruses in Mexico and the southern United States. Phytopathology, 86(Issue 11). doi:10.1094/phyto-86-1186
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  Plant samples from important horticultural areas in Mexico and the southern United States were collected during several seasons and analyzed for the presence of geminiviruses by a combination of agarose gel electrophoresis, molecular hybridization, and polymerase chain reaction amplification techniques. A general detection strategy confirmed the presence of geminiviruses in all horticultural areas of Mexico in pepper, tomato, tomatillo (Physalis ixocarpa), cucurbits, and tobacco. Specific detection procedures showed that pepper huasteco virus is widely distributed in Mexico; it was found in pepper and tomato samples in both coastal areas, as well as in central Mexico. It was also found in pepper samples from the Rio Grande Valley in southern Texas. Pepper jalapeno virus (PJV) and chino del tomate virus (CdTV) showed a more restricted distribution, although, in all cases, the viruses appeared to become more widely distributed over time. Partial DNA sequences of PJV and CdTV were also obtained. Comparative sequence analysis showed that PJV and the previously described Texas pepper geminivirus are probably strains of the same virus. The name pepper jalapeno virus is, thus, withdrawn to avoid further confusion. Similarly, CdTV showed a very high level of sequence identity with the recently described tomato leaf crumple virus (TLCrV), also suggesting that they both are strains of the same virus.
• Wyatt, S. D., & Brown, J. K. (1996). Detection of subgroup III geminivirus isolates in leaf extracts by degenerate primers and polymerase chain reaction. Phytopathology, 86(12), 1288-1293.
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  Abstract: The DNA of several monopartite and bipartite whitefly-transmitted (WFT) geminiviruses was amplified from a viral template present in infected leaves after either direct addition of clarified plant extracts to an otherwise complete polymerase chain reaction (PCR) mix or after immobilization of template to microfuge tubes. A degenerate primer pair was designed to specifically target the middle or 'core' region of the capsid protein gene of subgroup III geminivirus isolates and amplify a viral DNA fragment of approximately 550 bp. Using this method, a single PCR product of the expected size (550 bp), as estimated by agarose gel electrophoresis, was amplifiable from plants infected with a representative set of subgroup III geminivirus isolates with a broad biogeographic base. That the 550-bp PCR product had a geminiviral gene origin was demonstrated by direct sequencing of the 550-bp fragments (yielding approximately 470 to 490 bases of informative sequence) and was validated through comparison (alignment) of the sequences with the published DNA sequences of several well-characterized WFT geminiviruses. Analogous viral fragments were not detectable by PCR with the subgroup III core coat protein primers and extracts of plants infected with either subgroup I or II geminivirus isolates. The demonstrated exclusive specificity of the assay for subgroup III geminiviruses offers a highly simplified PCR- based assay that permits the detection of a geographically diverse collection of WFT geminiviruses infecting cultivated crops, ornamentals, and weed hosts with minimal sample preparation. This approach is highly useful for the amplification of subgroup III geminiviral DNA templates from total nucleic acid extracts from infected plants and partially purified virion preparations.
• Wyatt, S. D., & Brown, J. K. (1996). Detection of subgroup III geminivirus isolates in leaf extracts by degenerate primers and polymerase chain reaction. Phytopathology, 86(Issue 12). doi:10.1094/phyto-86-1288
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  The DNA of several monopartite and bipartite whitefly-transmitted (WFT) geminiviruses was amplified from a viral template present in infected leaves after either direct addition of clarified plant extracts to an otherwise complete polymerase chain reaction (PCR) mix or after immobilization of template to microfuge tubes. A degenerate primer pair was designed to specifically target the middle or 'core' region of the capsid protein gene of subgroup III geminivirus isolates and amplify a viral DNA fragment of approximately 550 bp. Using this method, a single PCR product of the expected size (550 bp), as estimated by agarose gel electrophoresis, was amplifiable from plants infected with a representative set of subgroup III geminivirus isolates with a broad biogeographic base. That the 550-bp PCR product had a geminiviral gene origin was demonstrated by direct sequencing of the 550-bp fragments (yielding approximately 470 to 490 bases of informative sequence) and was validated through comparison (alignment) of the sequences with the published DNA sequences of several well-characterized WFT geminiviruses. Analogous viral fragments were not detectable by PCR with the subgroup III core coat protein primers and extracts of plants infected with either subgroup I or II geminivirus isolates. The demonstrated exclusive specificity of the assay for subgroup III geminiviruses offers a highly simplified PCR- based assay that permits the detection of a geographically diverse collection of WFT geminiviruses infecting cultivated crops, ornamentals, and weed hosts with minimal sample preparation. This approach is highly useful for the amplification of subgroup III geminiviral DNA templates from total nucleic acid extracts from infected plants and partially purified virion preparations.
• Anthony, N. M., Brown, J. K., Markham, P. G., & Ffrench-Constant, R. H. (1995). Molecular analysis of cyclodiene resistance-associated mutations among populations of the sweetpotato whitefly bemisia tabaci. Pesticide Biochemistry and Physiology, 51(Issue 3). doi:10.1006/pest.1995.1022
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  Two polymerase chain reaction (PCR)-based molecular diagnostics were used to investigate whether cyclodiene resistance is uniquely associated with the novel “B” biotype of the sweetpotato whitefly Bemisia tabaci (Gennadius) and thus establish whether resistance could have acted as a driving force in the recent and rapid spread of this biotype. Previous studies have shown that a single point mutation coding for an alanine to serine replacement in the Drosophila Rdl gene confers high levels of resistance to cyclodiene insecticides. Following identification of an analogous point mutation in the B. tabaci Rdl homologue, PCR amplification of specific alleles demonstrated that the corresponding alanine to serine replacement is not confined to the B biotype but is also present in indigenous whitefly populations found on crop plants. Single-stranded conformational polymorphism (SSCP) analysis of the same region of the Rdl gene was used to confirm whitefly genotype and examine the degree of nucleotide polymorphism among whitefly strains. A comparison of SSCP banding patterns revealed a remarkable lack of nucleotide variation among strains conforming to the B biotype, whereas several of the non-B strains exhibited different banding patterns. Sequence analysis of these strains revealed one or more nucleotide polymerphisms including a novel resistance-associated mutation in one collection from the Sudan. These results show that cyclodiene resistance is not uniquely associated with the B biotype. However, the lack of genetic variability in the Rdl gene among B strains is consistent with the recent origin and spread of this novel biotype. © 1995 Academic Press. All rights reserved.
• Anthony, N. M., Brown, J. K., Markham, P. G., & ffrench-Constant, R. (1995). Molecular analysis of cyclodiene resistance-associated mutations among populations of the sweetpotato whitefly Bemisia tabaci. Pesticide Biochemistry and Physiology, 51(3), 220-228.
• Banks, G., Bird, J., Brown, J. K., Cabrera, I., Fornaris, G., Kiesler, K., & Sosa, M. (1995). First report of an epidemic in tomato caused by two whitefly-transmitted geminiviruses in Puerto Rico.. Plant Disease, 79(12), 1250. doi:10.1094/pd-79-1250a
• Brown, J. K., & Jessop, A. C. (1995). Genetics of avirulences in Erysiphe graminis f.sp. hordei. Plant Pathology, 44(6), 1039-1049. doi:10.1111/j.1365-3059.1995.tb02663.x
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  The genetics of avirulences towards barley mildew resistances were analysed in crosses of the Erysiphe graminis f.sp. hordei isolate DH14 with CC107 and with CC138. Nine avirulences, Avr a9 , Avr a10 , Avr a11 , Avr a12 , Avr Ab , Avr CP , Avr b , Avr k and Avr La , segregated as single genes in one or other cross. However, F segregation data were consistent with avirulence matching the Mla7 resistance gene being controlled by two genes, designated Avr a7 1 and Avr a7 2. Infection types of avirulent isolates differed on varieties in which Mla7 had been derived from each of the four known sources of that resistance. Linkage was detected between Avr a7 1 and Avr b in the cross CC107 x DH14, and between Avr a10 and Avr k , Avr a11 and Avr La , and Avr h and the triadimenol response gene Tdl2 in CC138 x DH14.
• Brown, J. K., Coats, S. A., Bedford, I. D., Markham, P. G., Bird, J., & Frohlich, D. R. (1995). Characterization and distribution of esterase electromorphs in the whitefly, Bemisia tabaci (Genn.) (Homoptera: Aleyrodidae). Biochemical Genetics, 33(7-8), 205-214.
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  PMID: 8595048;Abstract: Esterase profiles were examined for over 40 populations of the whitefly, Bemisia tabaci, obtained from native and cultivated plant hosts worldwide. Twelve unique electromorphs were identified from distinct populations concentrated largely in Central America, Africa, and India. One electromorph, type B, has recently been proposed as a separate species, Bemisia argentifolii, and has recently spread throughout much of the world. When considered with evidence from mating studies and the ability to induce phytotoxic disorders (squash silverleaf disorder), our data suggest that the single taxon Bemisia tabaci may actually represent a species complex. © 1995 Plenum Publishing Corporation.
• Brown, J. K., Coats, S. A., Bedford, I. D., Markham, P. G., Bird, J., & Frohlich, D. R. (1995). Characterization and distribution of esterase electromorphs in the whitefly, Bemisia tabaci (Genn.) (Homoptera: Aleyrodidae). Biochemical Genetics, 33(Issue 7). doi:10.1007/bf02401851
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  Esterase profiles were examined for over 40 populations of the whitefly, Bemisia tabaci, obtained from native and cultivated plant hosts worldwide. Twelve unique electromorphs were identified from distinct populations concentrated largely in Central America, Africa, and India. One electromorph, type B, has recently been proposed as a separate species, Bemisia argentifolii, and has recently spread throughout much of the world. When considered with evidence from mating studies and the ability to induce phytotoxic disorders (squash silverleaf disorder), our data suggest that the single taxon Bemisia tabaci may actually represent a species complex. © 1995, Plenum Publishing Corporation. All rights reserved.
• Brown, J. K., Frohlich, D. R., & Rosell, R. C. (1995). The sweetpotato or silverleaf whiteflies: Biotypes of Bemisia tabaci or a species complex?. Annual Review of Entomology, 40(1), 511-534.
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  Abstract: The recent emergence of whitefiy species of the genus Bemisia as virus vectors and pests worldwide has stimulated investigations into their biology. The invasion of pantropical agroecosystems by an exotic whitefiy and increased pressures by indigenous whiteflies elsewhere have led to the examination of Bemisia tabaci biology with a new perspective. The concept of host races or biotypes was proposed in the 1950s to describe select B. tabaci populations with definitive host associations and specific virus-vector capabilities. However, little attention has been given to the mechanisms involved. Biochemical, molecular, and whole-system approaches are underway to examine the underlying diversity among reproductively isolated populations or biotypes of B. tabaci.
• Brown, J. K., Frohlich, D. R., & Rosell, R. C. (1995). The sweetpotato or silverleaf whiteflies: Biotypes of Bemisia tabaci or a species complex?. Annual Review of Entomology. doi:10.1146/annurev.en.40.010195.002455
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  The recent emergence of whitefiy species of the genus Bemisia as virus vectors and pests worldwide has stimulated investigations into their biology. The invasion of pantropical agroecosystems by an exotic whitefiy and increased pressures by indigenous whiteflies elsewhere have led to the examination of Bemisia tabaci biology with a new perspective. The concept of host races or biotypes was proposed in the 1950s to describe select B. tabaci populations with definitive host associations and specific virus-vector capabilities. However, little attention has been given to the mechanisms involved. Biochemical, molecular, and whole-system approaches are underway to examine the underlying diversity among reproductively isolated populations or biotypes of B. tabaci.
• Costa, H. S., Westcot, D. M., Ullman, D. E., Rosell, R., Brown, J. K., & Johnson, M. W. (1995). Morphological variation in Bemisia endosymbionts. Protoplasma, 189(3-4), 194-202.
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  Abstract: The ultrastructure of the endosymbionts of several populations of whitefly (Homoptera: Aleyrodidae) was examined using transmission electron microscopy. Consistent differences in morphology and relative number of endosymbionts were observed between species and biotypes of whitefly within the Bemisia taxon. Bemisia argentifolii (=B. tabaci B biotype) individuals from Hawaii, Florida, and Arizona contained two morphological types of microorganisms housed within the mycetocyte cells of immature whiteflies. In contrast, individuals from populations of B. tabaci A biotype from Arizona and Mexico, and B. tabaci Jatropha biotype from Puerto Rico, consistently contained three distinct morphological types of microorganisms within their mycetocytes. Organisms from B. tabaci A and Jatropha biotypes differed from each other in the relative frequency of each type of microorganism. These observations suggest that different whitefly biotypes may have variable combinations of micro-fauna, with some possibly unique to each group, and furthers the hypothesis that variation in whitefly endosymbionts may be associated with the development of biotypes. © 1995 Springer-Verlag.
• Costa, H. S., Westcot, D. M., Ullman, D. E., Rosell, R., Brown, J. K., & Johnson, M. W. (1995). Morphological variation in Bemisia endosymbionts. Protoplasma, 189(Issue 3-4). doi:10.1007/bf01280174
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  The ultrastructure of the endosymbionts of several populations of whitefly (Homoptera: Aleyrodidae) was examined using transmission electron microscopy. Consistent differences in morphology and relative number of endosymbionts were observed between species and biotypes of whitefly within the Bemisia taxon. Bemisia argentifolii (=B. tabaci B biotype) individuals from Hawaii, Florida, and Arizona contained two morphological types of microorganisms housed within the mycetocyte cells of immature whiteflies. In contrast, individuals from populations of B. tabaci A biotype from Arizona and Mexico, and B. tabaci Jatropha biotype from Puerto Rico, consistently contained three distinct morphological types of microorganisms within their mycetocytes. Organisms from B. tabaci A and Jatropha biotypes differed from each other in the relative frequency of each type of microorganism. These observations suggest that different whitefly biotypes may have variable combinations of micro-fauna, with some possibly unique to each group, and furthers the hypothesis that variation in whitefly endosymbionts may be associated with the development of biotypes. © 1995 Springer-Verlag.
• Rosell, R. C., Lichty, J. E., & Brown, J. K. (1995). Ultrastructure of the mouthparts of adult sweetpotato whitefly, Bemisia tabaci Gennadius (Homoptera: Aleyrodidae). International Journal of Insect Morphology and Embryology, 24(3), 297-306.
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  Abstract: The fine structure of the mouthparts of the whitefly, Bemisia tabaci Gennadius (Homoptera: Aleyrodidae), was examined by scanning and transmission electron microscopy. Adult whitefly mouthparts are similar to those of other homopterans, especially aphids, being composed of the labrum, the labium, and the stylets. The stylet bundle is the feeding organ of the whitefly and is composed of 2 mandibular stylets and 2 maxillary stylets. Mandibular stylets, which are located on the outer aspect of the stylet bundle, each contain 2 dendrites. The tips of the mandibular stylets are curved inward, and there are barb-like ridges on the lateral aspects, which probably function in piercing and cutting plant tissues and in anchoring the stylets in the tissues. The maxillary stylets are not innervated and are interlocked to form 2 separate compartments, the food canal and salivary canal. At the distal end of the interlocked maxillary stylets, there is a small depression, which may allow for mixing of the salivary canal and food canal components. Movement of the B. tabaci stylets during feeding is discussed in comparison with other homopterans. © 1995.
• Rosell, R. C., Lichty, J. E., & Brown, J. K. (1995). Ultrastructure of the mouthparts of adult sweetpotato whitefly, Bemisia tabaci Gennadius (Homoptera: Aleyrodidae). International Journal of Insect Morphology and Embryology, 24(Issue 3). doi:10.1016/0020-7322(94)00026-m
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  The fine structure of the mouthparts of the whitefly, Bemisia tabaci Gennadius (Homoptera: Aleyrodidae), was examined by scanning and transmission electron microscopy. Adult whitefly mouthparts are similar to those of other homopterans, especially aphids, being composed of the labrum, the labium, and the stylets. The stylet bundle is the feeding organ of the whitefly and is composed of 2 mandibular stylets and 2 maxillary stylets. Mandibular stylets, which are located on the outer aspect of the stylet bundle, each contain 2 dendrites. The tips of the mandibular stylets are curved inward, and there are barb-like ridges on the lateral aspects, which probably function in piercing and cutting plant tissues and in anchoring the stylets in the tissues. The maxillary stylets are not innervated and are interlocked to form 2 separate compartments, the food canal and salivary canal. At the distal end of the interlocked maxillary stylets, there is a small depression, which may allow for mixing of the salivary canal and food canal components. Movement of the B. tabaci stylets during feeding is discussed in comparison with other homopterans. © 1995.
• Thomas, J. C., Adams, D. G., Keppenne, V. D., Wasmann, C. C., Brown, J. K., Kanost, M. R., & Bohnert, H. J. (1995). Protease inhibitors of Manduca sexta expressed in transgenic cotton. Plant Cell Reports, 14(12), 758-762.
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  Abstract: To explore the effectiveness of insect derived protease inhibitors in protecting plants against insect feeding, anti-trypsin, anti-chymotrypsin and anti-elastase protease inhibitor (PI) genes from Manduca sexta L. were expressed in transgenic cotton (Gossypium hirsutum L.). From 198 independent transformants, 35 elite lines were further analyzed. Under the control of the 35S promoter of CaMV, PI accumulated to approximately 0.1% of total protein, depending on the tissue analyzed. Using cell-flow cytometry, DNA content/ nuclei of transgenic and non-transformed cotton were identical. On cotton plants expressing PIs, fecundity of Bemisia tabaci (Genn.), the sweetpotato whitefly, was reduced compared to controls. Expression of these protease inhibitors may reduce the developmental rate of B. tabaci and other insects, and provide a strategy for cotton protection. © 1995 Springer-Verlag.
• Thomas, J. C., Adams, D. G., Keppenne, V. D., Wasmann, C. C., Brown, J. K., Kanost, M. R., & Bohnert, H. J. (1995). Protease inhibitors of Manduca sexta expressed in transgenic cotton. Plant Cell Reports, 14(Issue 12). doi:10.1007/bf00232917
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  To explore the effectiveness of insect derived protease inhibitors in protecting plants against insect feeding, anti-trypsin, anti-chymotrypsin and anti-elastase protease inhibitor (PI) genes from Manduca sexta L. were expressed in transgenic cotton (Gossypium hirsutum L.). From 198 independent transformants, 35 elite lines were further analyzed. Under the control of the 35S promoter of CaMV, PI accumulated to approximately 0.1% of total protein, depending on the tissue analyzed. Using cell-flow cytometry, DNA content/ nuclei of transgenic and non-transformed cotton were identical. On cotton plants expressing PIs, fecundity of Bemisia tabaci (Genn.), the sweetpotato whitefly, was reduced compared to controls. Expression of these protease inhibitors may reduce the developmental rate of B. tabaci and other insects, and provide a strategy for cotton protection. © 1995 Springer-Verlag.
• Thomas, J. C., Adams, D. G., Nessler, C. L., Brown, J. K., & Bohnert, H. J. (1995). Tryptophan decarboxylase, tryptamine, and reproduction of the whitefly. Plant Physiology, 109(2), 717-720.
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  Abstract: Tryptophan decarboxylase (TDC) from Catharanthus roseus (periwinkle) converts tryptophan to the indole-alkaloid tryptamine. When the TDC gene was expressed in transgenic tobacco, the 55-kD TDC enzyme and tryptamine accumulated. Bemisia tabaci (sweetpotato whitefly) reproduction on transgenic plants decreased up to 97% relative to controls. Production of tryptamine, its derivatives, or other products resulting from TDC activity may discourage whitefly reproduction and provide a single-gene-based plant protection strategy.
• Thomas, J. C., Adams, D. G., Nessler, C. L., Brown, J. K., & Bohnert, H. J. (1995). Tryptophan decarboxylase, tryptamine, and reproduction of the whitefly. Plant Physiology, 109(Issue 2). doi:10.1104/pp.109.2.717
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  Tryptophan decarboxylase (TDC) from Catharanthus roseus (periwinkle) converts tryptophan to the indole-alkaloid tryptamine. When the TDC gene was expressed in transgenic tobacco, the 55-kD TDC enzyme and tryptamine accumulated. Bemisia tabaci (sweetpotato whitefly) reproduction on transgenic plants decreased up to 97% relative to controls. Production of tryptamine, its derivatives, or other products resulting from TDC activity may discourage whitefly reproduction and provide a single-gene-based plant protection strategy.
• Wasmann, C. C., Thomas, J. C., Keppenne, V. D., Kanost, M. R., Brown, J. K., Bohnert, H. J., & Adams, D. G. (1995). Manduca sexta encoded protease inhibitors expressed in Nicotiana tabacum provide protection against insects. Plant Physiology and Biochemistry, 33(5), 611-614.
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  Crop plants are damaged by a multitude of insect pests, lowering crop quality and yield. Here we have expressed insect encoded anti-trypsin, anti-chymotrypsin and anti-elastase protease inhibitor (PI) genes from Manduca sexta L. in transgenic Nicotiana tabacum L. under the control of the 35S promoter of cauliflower mosaic virus. PI levels accumulated in leaves to 0.05-0.1% of the total protein. When these plants were tested against the new Bemisia tabaci (Genn.), sweetpotato whitefly type B, insect reproduction was reduced by as much as 98 % compared to controls. This result suggests that M. sexta derived protease inhibitors, together with other anti-insect genes and plant-encoded responses to damage and attack, may be useful in protecting crop plants against insects.
• BEDFORD, I. D., BRIDDON, R. W., BROWN, J. K., ROSELL, R. C., & MARKHAM, P. G. (1994). Geminivirus transmission and biological characterisation of Bemisia tabaci (Gennadius) biotypes from different geographic regions. Annals of Applied Biology, 125(Issue 2). doi:10.1111/j.1744-7348.1994.tb04972.x
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  Eighteen populations of Bemisia tabaci, collected from different geographic locations (North & Central America, the Caribbean, Africa, the Middle East, Asia and Europe), were studied to identify and compare biological and genetic characteristics that can be used to differentiate biotypes. The morphology of the fourth instar/pupal stage and compound eye structures of adults were investigated using scanning electron microscopy and found to be typical of the species among all biotypes and populations studied. Setae and spines of B. tabaci larval scales from the same colony were highly variable depending on the host plant species or leaf surface characteristics. The location and the morphology of caudal setae, characteristic of all B. tabaci studied to date, were present in all colonies. However, differences in adult body lengths and in the ability to induce phy to toxic disorders in certain plant species were found between biotypes or populations. The recently identified “B” biotype, characterised by a diagnostic esterase banding pattern and by its ability to induce phytotoxic responses in squash, honeysuckle and nightshade was readily distinguished from non‐“B” biotype populations. None of the non‐“B” biotypes studied, were found to induce phytotoxic responses. Nine populations examined showed typical “B” biotype characteristics, regardless of country of origin. All tested populations, determined as “B” or “B”‐like biotypes successfully mated with other “B” biotype colonies from different geographic areas. Non‐“B” biotype colonies did not interbreed with other biotypes. The B. tabaci populations were tested for their ability to transmit 15 whitefly‐transmitted geminiviruses (WTGs) from different geographic areas with a wide range of symptom types. All WTGs were transmitted by the “B” biotype colonies and by most non‐“B” biotype colonies, with the exception of three viruses found in ornamental plants which were non‐transmissible by any colony. Some non‐“B” biotypes would not transmit certain geminiviruses and some geminiviruses were more efficiently transmitted than were others. Copyright © 1994, Wiley Blackwell. All rights reserved
• Bedford, I. D., Briddon, R. W., Brown, J. K., Rosell, R. C., & Markham, P. G. (1994). Geminivirus-transmission and biological characterisation of Bermisia tabaci (Gennadius) biotypes from different geographic regions. Annals of Applied Biology, 125(2), 311-326.
• Brown, J. K. (1994). Bootstrap hypothesis tests for evolutionary trees and other dendrograms.. Proceedings of the National Academy of Sciences of the United States of America, 91(25), 12293-7. doi:10.1073/pnas.91.25.12293
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  The bootstrap computer-intensive statistical technique is frequently applied to statistical analyses of phylogenetic trees. The widely used rule that a group is supported significantly if it appears in at least 95% of bootstrap trees is conservative in most situations. This paper describes three ways of using the bootstrap to carry out statistical inference on phylogenies. The first method tests whether there is nonrandom support for a single group or tree. The second method compares the support for two groups or trees. The third method tests whether a single group or tree has better support than the set of all possible alternatives; this may be a replacement for the "95% rule." These tests generally require fewer bootstrap trees to be estimated than do other methods of bootstrapping phylogenies. A simple, sequential statistical method can be used to increase the efficiency further. These methods can be applied to tests of multiple hypotheses about a single phylogeny. Parsimony analyses of 5S rRNA sequences of plants and cluster analyses of randomly amplified polymorphic DNA bands in three pathotypes of the cereal eyespot fungus are used as illustrative examples. The tests can be used to analyze dendrograms in subjects other than taxonomy.
• Coats, S. A., Brown, J. K., & Hendrix, D. L. (1994). Biochemical characterization of biotype-specific esterases in the whitefly, Bemisia tabaci Genn (homoptera: Aleyrodidae). Insect Biochemistry and Molecular Biology, 24(7), 723-728.
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  Abstract: Biochemical properties of the predominant esterases found in two distinct populations, presently considered to be different biotypes of the whitefly Bemisia tabaci, were investigated. General esterases, previously established as diagnostic markers on native polyacrylamide gels (PAGE) for the 'A' and 'B' biotypes, were characterized with respect to molecular masses, isoelectric points (pIs), isomeric relationships, and substrate specificities. One previously unidentified band in the 'B' biotype was detected on native gels when ethylenediaminetetracetic acid (EDTA) was added to gel buffers. In each of the 'A' and 'B' biotypes, 12 bands were resolved by isoelectric focusing (IEF), and had pIs ranging from 4.86 to 7.37, and 4.70 to 6.59, respectively. The two bands ('B'1 and 'B'2), used as diagnostic markers on native gels for the 'B' biotype, were identified as a single band (E7) with IEF. An analogous E7 band was resolved in the 'A' biotype with IEF, but corresponded to only one isomer (A6) on native gels. Results of substrate studies revealed most bands on IEF gels had carboxylesterase activity. The E7 esterase in each biotype was identified specifically as acetylcholinesterase (AChE). Ferguson plots revealed these E7 esterases of the 'A' and 'B' biotypes had equivalent charges, but different molecular masses, indicating they are size isomers. Two dimensional (2D) and IEF analyses confirmed this relationship. © 1994.
• Coats, S. A., Brown, J. K., & Hendrix, D. L. (1994). Biochemical characterization of biotype-specific esterases in the whitefly, Bemisia tabaci Genn (homoptera: Aleyrodidae). Insect Biochemistry and Molecular Biology, 24(Issue 7). doi:10.1016/0965-1748(94)90060-4
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  Biochemical properties of the predominant esterases found in two distinct populations, presently considered to be different biotypes of the whitefly Bemisia tabaci, were investigated. General esterases, previously established as diagnostic markers on native polyacrylamide gels (PAGE) for the 'A' and 'B' biotypes, were characterized with respect to molecular masses, isoelectric points (pIs), isomeric relationships, and substrate specificities. One previously unidentified band in the 'B' biotype was detected on native gels when ethylenediaminetetracetic acid (EDTA) was added to gel buffers. In each of the 'A' and 'B' biotypes, 12 bands were resolved by isoelectric focusing (IEF), and had pIs ranging from 4.86 to 7.37, and 4.70 to 6.59, respectively. The two bands ('B'1 and 'B'2), used as diagnostic markers on native gels for the 'B' biotype, were identified as a single band (E7) with IEF. An analogous E7 band was resolved in the 'A' biotype with IEF, but corresponded to only one isomer (A6) on native gels. Results of substrate studies revealed most bands on IEF gels had carboxylesterase activity. The E7 esterase in each biotype was identified specifically as acetylcholinesterase (AChE). Ferguson plots revealed these E7 esterases of the 'A' and 'B' biotypes had equivalent charges, but different molecular masses, indicating they are size isomers. Two dimensional (2D) and IEF analyses confirmed this relationship. © 1994.
• Nelson, D. R., Allen, J. C., Brewster, C. C., Naranjo, S. E., Ellsworth, P. C., Natwick, E. T., Kirk, A. A., Heinz, K. M., Hoelmer, K. A., Hunter, M. S., Dennehy, T. J., Zolnerowich, G., Ziegweid, K., Yates, L., Wyatt, S. D., Wendel, L., Weinberg, A., Watson, T. F., Veierov, D., , Vecek, D., et al. (1994). Abstracts of Papers Presented at The International Workshop onBemisia Spp.. Phytoparasitica, 22(4), 309-359. doi:10.1007/bf02980532
• Smith, P. H., Green, R. M., Brown, J. K., & Boyd, L. A. (1994). The relationship between the expression of defense-related genes and mildew development in Barley. Molecular Plant-microbe Interactions, 7(3), 401-410. doi:10.1094/mpmi-7-0401
• Smith, S., Smith, P. H., Brown, J. K., & Boyd, L. A. (1994). Molecular and cellular expression of quantitative resistance in barley to powdery mildew. Physiological and Molecular Plant Pathology, 45(1), 47-58. doi:10.1016/s0885-5765(05)80018-9
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  The induction of five defence-related genes was examined in two barley cvs, P-03 and S-03, in direct relation to the growth and development of two near-isogenic Erysiphe graminis f.sp. hordei isolates, CC142 ( Aa6 ) and CC143 ( Va6 ). The barley cvs contained the mildew resistance gene Mla6 , while the E. graminis f.sp. hordei isolates differed only in virulence to Mla6 . Differences in the development of the two isolates on the two cvs were reflected in the patterns of defence gene induction. The defence genes examined included a chitinase, a peroxidase, a phenylalanine ammonia lyase, a leaf-specific thionin and a gene showing homology to the pathogenesis-related R protein from tobacco. The two isolates showed similar patterns of development up to 16 h after inoculation. At this time, a retardation in the development of the avirulent isolate, CC142, became apparent on S-03. However, inhibition of CC142 on P-03 was not seen until 48 h after inoculation. This difference in CC142 development was paralleled by an earlier, specific defence gene response to the avirulent isolate in S-03. By 16 h after inoculation higher transcript levels of the chitinase and the peroxidase genes were seen in S-03, while in P-03, a specific defence gene response to CC142 was only seen after 24 h. The earlier defence gene response, seen in S-03 to the avirulent isolate, may contribute to the earlier inhibition of CC142 development seen on this cultivar.
• Kirk, A. A., Lacey, L. A., Roditakis, N., & Brown, J. K. (1993). The status of Bemisia tabaci (Hom.: Aleyrodidae), Trialeurodes vaporariorum (Hom.: Aleyrodidae) and their natural enemies in Crete. Entomophaga, 38(3), 405-410.
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  Abstract: The non «B» biotype of Bemisia tabaci (Gennadius) is recorded for the first time in Crete in 1992, in the north east and south east of the island. Trialeurodes vaporariorum (Westwood) is the predominant whitefly on plants in the north and west of the island. Three surveys of Crete were made in 1992 and 1993 for natural enemies of B. tabaci and T. vaporariorum and resulted in the collection of 4 species of Encarsia, (plus a number of species that are unidentifiable at this time), an Eretmocerus sp. (unidentifiable at this time) and a fungal pathogen, Paecilomyces farinosus (Dickson Ex Fries) Brown & Smith. Encarsia adrianae was identified from T. vaporariorum; which constitutes its most westerly distribution point and a new host record respectively. B. tabaci and T. vaporariorum were found on horticultural crops, ornamentals and weeds. Populations of both whitefly species were severely depleted on field hosts throughout the island during the winter of 1992/93. Climatic constraints, competition with T. vaporariorum in otherwise suitable niches, effective natural enemies and an observed low level of polyphagy may explain the present limited distribution of the non «B» biotype of B. tabaci in Crete. © 1993 Lavoisier Abonnements.
• Kirk, A. A., Lacey, L. A., Roditakis, N., & Brown, J. K. (1993). The status of Bemisia tabaci (Hom.: Aleyrodidae), Trialeurodes vaporariorum (Hom.: Aleyrodidae) and their natural enemies in Crete. Entomophaga, 38(Issue 3). doi:10.1007/bf02374458
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  The non «B» biotype of Bemisia tabaci (Gennadius) is recorded for the first time in Crete in 1992, in the north east and south east of the island. Trialeurodes vaporariorum (Westwood) is the predominant whitefly on plants in the north and west of the island. Three surveys of Crete were made in 1992 and 1993 for natural enemies of B. tabaci and T. vaporariorum and resulted in the collection of 4 species of Encarsia, (plus a number of species that are unidentifiable at this time), an Eretmocerus sp. (unidentifiable at this time) and a fungal pathogen, Paecilomyces farinosus (Dickson Ex Fries) Brown & Smith. Encarsia adrianae was identified from T. vaporariorum; which constitutes its most westerly distribution point and a new host record respectively. B. tabaci and T. vaporariorum were found on horticultural crops, ornamentals and weeds. Populations of both whitefly species were severely depleted on field hosts throughout the island during the winter of 1992/93. Climatic constraints, competition with T. vaporariorum in otherwise suitable niches, effective natural enemies and an observed low level of polyphagy may explain the present limited distribution of the non «B» biotype of B. tabaci in Crete. © 1993 Lavoisier Abonnements.
• Sivasupramaniam, S., Costa, H. S., Brown, J. K., & Bird, J. (1993). Regional Distribution, Insecticide Resistance, and Reciprocal Crosses Between the A and B Biotypes of Bemisia Tabaci. International Journal of Tropical Insect Science, 14(02), 255-266. doi:10.1017/s1742758400014703
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  Populations of the whitefly, Bemisia tabaci collected from the Americas and the Caribbean Basin were examined for non-specific esterases and for the ability to induce characteristic phytotoxic disorders in key assay species as a means of investigating biogeographic diversity. Esterase markers were used to detect polymorphisms among regional B. tabaci populations and to establish the present distribution of B. tabaci biotypes in the region. The A biotype occurred only in contiguous locales in northern Mexico and the southwestern US, while the B biotype was present throughout much of the Caribbean Basin and the US, and in Brazil. Distinct C and D type esterase markers were observed for Costa Rican and Nicaraguan B. tabaci populations, respectively. The 0 or null type population was collected only from Jatropha gossypifolia (L.) in Puerto Rico. Laboratory colonies of the A and the B biotypes were almost equally sensitive to an organophosphate, profenofos. The B biotype was more resistant to a pyrethroid, permethrin, suggesting the existence of a biotype of fi. tabaci, with a history of exposure to pesticides with a pyrethroid-based chemistry. In mating studies involving reciprocal crosses between the A and the B biotypes, very few F, female progeny were produced, indicating either minimal or non-existent reproductive compatibility between these haplo-diploid B. tabaci populations, presently considered to be the same species. Evidence is presented for the recent and widespread introduction, and subsequent spread of the B biotype throughout the US, the Caribbean Basin, and other proximal locations.
• Bedford, I. D., Briddon, R. W., Markham, P. G., Brown, J. K., & Rosell, R. C. (1992). Bemisia tabaci - biotype characterisation and the threat of this whitefly species to agriculture.. Proc. 1992 Brighton Crop Protection Conference - Pests and Diseases, 3, 1235-1240.
• Brown, J. K., & Bird, J. (1992). Whitefly-transmitted geminiviruses and associated disorders in the Americas and the Caribbean Basin.. Plant Disease, 76(3), 220-225. doi:10.1094/pd-76-0220
• Brown, J. K., Jessop, A. C., Rezanoor, H. N., & Thomas, S. (1992). Genetic control of the response of Erysiphe graminis f.sp. hordei to ethirimol and triadimenol. Plant Pathology, 41(2), 126-135. doi:10.1111/j.1365-3059.1992.tb02329.x
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  A study was conducted on the genetic control of the response of Erysiphe graminis f.sp. hordei, the causal agent of barley powdery mildew, to two fungicides: the hydroxypyrimidine ethirimol, and the triazole, sterol demethylation inhibitor triadimenol. In tests of responses to both fungicides, sets of progeny of various crosses were classified by principal components analysis into discrete resistant and sensitive classes. A single allele controlled the response to ethirimol of the resistant isolate DH14 in crosses with the sensitive isolates CC52 and CC138. The ethirimol-resistance alleles of DH14 and another resistant isolate. CC107, are at the same locus or are closely linked. Alleles at single loci controlled resistance and sensitivity to triadimenol in crosses of DH14 (sensitive) with CC107 (moderately resistant) and CC138 (highly resistant). There was no evidence for polygenic control of response to either fungicide. The ethirimol response locus and the two putative triadimenol response loci are designated Eth1 and Tdl1 and Tdl2, respectively. There was no evidence for linkage of Eth1 and Tdl2 in the cross CC138 × DH14, in which responses to both fungicides segregated.
• Parrelta, M. P., Heinz, K. M., Gill, R. J., Brown, J. K., & Bellows, T. S. (1992). Sweetpotato whitefly: prospects for biological control. California Agriculture, 46(1), 25-26. doi:10.3733/ca.v046n01p25
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  The damage to desert agricultural crops in Southern California and Arizona in fall-winter 1991 by the sweetpotato whitefly, Bemisia tabaci (Gennadius) is unprecedented in the history of the South west. Damage estimates exceed $200 million for California alone with the complete loss of the fall and winter melon crop and major damage to many winter vegetables and other crops. Origins of the problem, and potential biological control agents, are discussed.
• Poulos, B. T., Brown, J. K., Harrison, B. D., Poulos, B. T., & Swanson, M. M. (1992). Genome affinities and epitope profiles of whitefly-transmitted geminiviruses from the Americas. Annals of Applied Biology, 121(2), 285-296. doi:10.1111/j.1744-7348.1992.tb03441.x
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  Summary The relationships among fifteen isolates of whitefly-transmitted geminiviruses (WTGs) from North, Central and South America and six from other continents were assessed (a) in nucleic acid hybridisation tests with sulphonated DNA probes for eight of the viruses, and/or (b) in triple-antibody-sandwich ELISA with panels of monoclonal antibodies (MAbs) to particles of African cassava mosaic virus (ACMV) and Indian cassava mosaic virus (ICMV). Probes specific for DNA-A of four American viruses, abutilon mosaic (AbMV), bean golden mosaic (BGMV), squash leaf curl (SLCV) and tomato golden mosaic (TGMV), detected virtually all the American viruses but reacted weakly if at all with ICMV, ACMV or tomato yellow leaf curl virus from Thailand (TYLCV-T). Conversely, the probe for ACMV DNA-A did not detect any of the American viruses, and that for TYLCV-T DNA-A reacted weakly with SLCV and TGMV0020but did not detect the others. In contrast, probes specific for DNA-B of the four American viruses or ACMV detected only the homologous virus, except for slight reactions between the AbMV DNA-B probe and both chino del tomate virus (CdTV)-DNA and SLCV-DNA. However, a probe for DNA-B of bean calico mosaic virus (BCMoV) reacted weakly with BGMV-PR DNA, and a probe for DNA-B of CdTV from Mexico detected several American viruses. Six out of 17 MAbs specific for ACMV and six out of 10 MAbs specific for ICMV reacted with one or other of the 14 American virus isolates tested. Two and-ACMV MAbs reacted with all, and one anti-ACMV MAb and two anti-ICMV MAbs reacted with nearly all the American viruses, one anti-ACMV MAb reacted with about half the American viruses and six other MAbs reacted with only one or two of them. Of the American viruses, CdTV and AbMV were the least closely related to the others. The epitope profiles of BCMoV, BGMV, cotton leaf crumple virus, serrano golden mosaic virus and SLCV were virtually indistinguishable. TGMV, potato yellow mosaic virus (PYMV) and an euphorbia virus had profiles intermediate between those of the BGMV cluster and AbMV-CdTV. In general, the epitope profiles and the results of hybridisation tests with DNA-A probes show that the similarities among the American viruses are greater than those between the American viruses and the viruses from other continents; the hybridisation tests with DNA-B probes show that substantial differences exist between individual American viruses. In America, geminivirus evolution seems to have proceeded convergently from different progenitor viruses, or divergently from one ancestral form, with DNA-B diverging to a greater extent than DNA-A and its particle-protein gene.
• SWANSON, M., BROWN, J., POULOS, B., & HARRISON, B. (1992). Genome affinities and epitope profiles of whitefly‐transmitted geminiviruses from the Americas. Annals of Applied Biology, 121(2). doi:10.1111/j.1744-7348.1992.tb03441.x
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  The relationships among fifteen isolates of whitefly‐transmitted geminiviruses (WTGs) from North, Central and South America and six from other continents were assessed (a) in nucleic acid hybridisation tests with sulphonated DNA probes for eight of the viruses, and/or (b) in triple‐antibody‐sandwich ELISA with panels of monoclonal antibodies (MAbs) to particles of African cassava mosaic virus (ACMV) and Indian cassava mosaic virus (ICMV). Probes specific for DNA‐A of four American viruses, abutilon mosaic (AbMV), bean golden mosaic (BGMV), squash leaf curl (SLCV) and tomato golden mosaic (TGMV), detected virtually all the American viruses but reacted weakly if at all with ICMV, ACMV or tomato yellow leaf curl virus from Thailand (TYLCV‐T). Conversely, the probe for ACMV DNA‐A did not detect any of the American viruses, and that for TYLCV‐T DNA‐A reacted weakly with SLCV and TGMV0020but did not detect the others. In contrast, probes specific for DNA‐B of the four American viruses or ACMV detected only the homologous virus, except for slight reactions between the AbMV DNA‐B probe and both chino del tomate virus (CdTV)‐DNA and SLCV‐DNA. However, a probe for DNA‐B of bean calico mosaic virus (BCMoV) reacted weakly with BGMV‐PR DNA, and a probe for DNA‐B of CdTV from Mexico detected several American viruses. Six out of 17 MAbs specific for ACMV and six out of 10 MAbs specific for ICMV reacted with one or other of the 14 American virus isolates tested. Two and‐ACMV MAbs reacted with all, and one anti‐ACMV MAb and two anti‐ICMV MAbs reacted with nearly all the American viruses, one anti‐ACMV MAb reacted with about half the American viruses and six other MAbs reacted with only one or two of them. Of the American viruses, CdTV and AbMV were the least closely related to the others. The epitope profiles of BCMoV, BGMV, cotton leaf crumple virus, serrano golden mosaic virus and SLCV were virtually indistinguishable. TGMV, potato yellow mosaic virus (PYMV) and an euphorbia virus had profiles intermediate between those of the BGMV cluster and AbMV‐CdTV. In general, the epitope profiles and the results of hybridisation tests with DNA‐A probes show that the similarities among the American viruses are greater than those between the American viruses and the viruses from other continents; the hybridisation tests with DNA‐B probes show that substantial differences exist between individual American viruses. In America, geminivirus evolution seems to have proceeded convergently from different progenitor viruses, or divergently from one ancestral form, with DNA‐B diverging to a greater extent than DNA‐A and its particle‐protein gene. Copyright © 1992, Wiley Blackwell. All rights reserved
• Brown, J. K. (1991). An update on the whitefly-transmitted geminiviruses in the Americas and the Caribbean Basin. FAO Plant Protection Bulletin, 39(1), 5-23.
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  Abstract: Whitefly-transmitted (WFT) geminiviruses that cause epidemics in vegetable, staple and fibre crops are increasing in prevalence and distribution in subtropical, tropical and fringe temperate regions of the world. This article reviews the research on WFT geminiviruses and presents results substantiating the need for a more thorough investigation of tropical weed species which serve as potential sources of undescribed and uncharacterized WFT geminiviruses. -from Author
• Brown, J. K. (1991). An update on the whitefly-transmitted geminiviruses in the Americas and the Caribbean Basin. FAO Plant Protection Bulletin, 39(Issue 1).
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  Whitefly-transmitted (WFT) geminiviruses that cause epidemics in vegetable, staple and fibre crops are increasing in prevalence and distribution in subtropical, tropical and fringe temperate regions of the world. This article reviews the research on WFT geminiviruses and presents results substantiating the need for a more thorough investigation of tropical weed species which serve as potential sources of undescribed and uncharacterized WFT geminiviruses. -from Author
• Brown, J. K., & Costa, H. S. (1991). Biological Characteristics and Esterase Patterns for Bemisia tabaci Populations, and the Association of Silverleaf Symptom Development in Squash with One Population. Entomol. Exp. Appl., 61, 211-219.
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  Biological characteristics (oviposition and survival rates) and esterase banding patterns were investigated to evaluate the extent of variation among three test populations of Bemisia tabaci Gennadius (Homoptera. Aleyrodidae). In terms of reproductive capabilities, whiteflies from the cotton (Gossvviurn hirsutum L.) and pumpkin (Cucurbita maxima Duchesne) populations performed similarly on the three host plant species tested. Both populations, which originated from the same wild -type field population, reproduced to higher levels on either cotton and pumpkin hosts than on a poinsettia (Euahorbia vulcherrirna Willdenow) host. In contrast, whiteflies from the poinsettia population differed from cottonand pumpkinreared populations in that reproductive capabilities were relatively similar for the three host species tested. For whiteflies from pumpkin and cotton populations a similar and characteristic esterase banding pattern ( "Atype ") was observed, while whiteflies from the poinsettia population yielded a different banding pattern ( "Btype "). In transmission studies, whiteflies from cotton or pumpkin sources did not induce silverleaf (SL) or white stem (WS) symptoms in Cucurbita spp. tested. In contrast, poinsettia population whiteflies were routinely associated with SL and WS symptom phenotypes which developed in Cucurbita spp. following exposure to whitefly adults. From these data, it is possible to correlate a specific esterase banding pattern (A or B) with reproductive capabilities and either the ability or inability to induce SL and WS symptoms. Introduction In the past decade the importance of the whitefly, Bemisia tabaci Gennadius, as serious pest in vegetable and fiber crops has increased on a worldwide basis. Recently, symptoms like those described for the squash silverleaf disorder (SSL) in Cucurbita spp. (Maynard and Cantliffe, 1989), were observed in field zucchini and pumpkin in Arizona (1989 and 1990 authors, pers. observ.). Although feeding by B. tabaci (Maynard and Cantliffe, 1989; Yokomi et al., 1990) and the presence of two doublestranded RNAs (Bharathan et al., 1990) have been associated with the disorder, the etiology of this disease is unknown. Despite the unprecedented B. tabaci population levels which have been associated with increased virus incidence in the Southwestern U. S. during the past decade, SSL symptoms were not observed in Arizona until 1989. This observation suggests that either a recent change has occurred in endemic B. tabaci populations, or that an exotic population with different biological and/or genetic characteristics possibly affiliated with the SSL disorder has become prevalent.
• Costa, H. S., & Brown, J. K. (1991). Variation in biological characteristics and esterase patterns among populations of Bemisia tabaci, and the association of one population with silverleaf symptom induction. Entomologia Experimentalis et Applicata, 61(3), 211-219.
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  Abstract: Biological characteristics (oviposition and survival rates) and esterase banding patterns in native PAGE were investigated to evaluate variation among three populations of Bemisia tabaci Gennadius (Homoptera: Aleyrodidae). Reproductive capabilities of whiteflies from cotton (Gossypium hirsutum L.) and pumpkin (Cucurbita maxima Duchesne) populations were similar on the three host plant species tested. These populations, which had the same wild-type field origin, reproduced better on either cotton and pumpkin than on poinsettia (Euphorbia pulcherrima Willdenow). In contrast, poinsettia whiteflies exhibited relatively similar reproductive capabilities for the three host species tested. Pumpkin and cotton whiteflies had similar esterase banding patterns ('A' type), while poinsettia whiteflies yielded a different banding pattern ('B' type). In transmission studies, whiteflies from cotton or pumpkin sources did not induce silverleaf (SSL) or white stem (WS) symptoms in Cucurbita spp. tested. In contrast, poinsettia whiteflies were associated routinely with SSL and WS symptoms in Cucurbita spp. following colonization by whitefly adults. From these data, it was possible to correlate a specific esterase banding pattern (A or B) with reproductive capabilities and the ability to induce SSL and WS symptoms. © 1991 Kluwer Academic Publishers.
• Costa, H. S., & Brown, J. K. (1991). Variation in biological characteristics and esterase patterns among populations of Bemisia tabaci, and the association of one population with silverleaf symptom induction. Entomologia Experimentalis et Applicata, 61(Issue 3). doi:10.1111/j.1570-7458.1991.tb01553.x
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  Biological characteristics (oviposition and survival rates) and esterase banding patterns in native PAGE were investigated to evaluate variation among three populations of Bemisia tabaci Gennadius (Homoptera: Aleyrodidae). Reproductive capabilities of whiteflies from cotton (Gossypium hirsutum L.) and pumpkin (Cucurbita maxima Duchesne) populations were similar on the three host plant species tested. These populations, which had the same wild-type field origin, reproduced better on either cotton and pumpkin than on poinsettia (Euphorbia pulcherrima Willdenow). In contrast, poinsettia whiteflies exhibited relatively similar reproductive capabilities for the three host species tested. Pumpkin and cotton whiteflies had similar esterase banding patterns ('A' type), while poinsettia whiteflies yielded a different banding pattern ('B' type). In transmission studies, whiteflies from cotton or pumpkin sources did not induce silverleaf (SSL) or white stem (WS) symptoms in Cucurbita spp. tested. In contrast, poinsettia whiteflies were associated routinely with SSL and WS symptoms in Cucurbita spp. following colonization by whitefly adults. From these data, it was possible to correlate a specific esterase banding pattern (A or B) with reproductive capabilities and the ability to induce SSL and WS symptoms. © 1991 Kluwer Academic Publishers.
• Costa, H. S., Byrne, D. N., & Brown, J. K. (1991). Life history traits of the whitefly, Bemisia tabaci (Homoptera: Aleyrodidae) on six virus-infected or healthy plant species. Environmental Entomology, 20(4), 1102-1107. doi:10.1093/ee/20.4.1102
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  In some cases, infection by plant viruses can alter host plant quality for homopterous insects. In these experiments, adult whiteflies from a population of Bemisia tabaci (Gennadius) that had been reared continuously on pumpkin plants for more than five years, were exposed to six plant species infected with one of four whitefly-transmitted plant viruses. The life history traits of whiteflies on virus-infected hosts were compared to those of whiteflies exposed to corresponding healthy hosts. Significant differences were found in progeny survival and oviposition rate among the six healthy hosts. Survival on healthy hosts ranked as follows: zucchini > cantaloupe = cotton = pumpkin > lettuce = tomato. Oviposition and immature survival rates varied between healthy and virus-infected host plants. The mean proportion of eggs surviving to adulthood was higher on pumpkin plants infected with watermelon curly mottle strain of squash leaf curl virus (WCMoV/SLCV) than on healthy pumpkin. Significantly lower mean proportion of offspring survived to adulthood on WCMoV/SLCV-infected zucchini, chino del tomate virus-infected tomato, and cotton leaf crumple virus-infected cotton compared to whiteflies on healthy control plants. For other virus-infected–healthy combinations, there were no significant differences in survival rates. No correlation was observed between levels of total free amino acids in healthy and infected plants and rates of oviposition or survival. The lack of correlation between oviposition and survival rates on healthy and infected plants, suggests that B. tabaci does not assess host suitability to regulate oviposition with respect to the projected host suitability for offspring survival.
• Costa, H., Brown, J. K., Byrne, D. N., Brown, J., Byrne, D., & Costa, H. S. (1991). Host plant selection by the whitefly, Bemisia tabaci (Gennadius), (Hom., Aleyrodidae) under greenhouse conditions. Journal of Applied Entomology, 112, 146-152. doi:10.1111/j.1439-0418.1991.tb01040.x
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  The whitefly, Bemisia tabaci (Gennadius), is of considerable economic importance as a pest and a virus vector in the tropical and subtropical regions of the world. One aspect of whitefly behaviour that is not well understood, is how they select host plants for feeding and oviposition. These factors directly impact whitefly population dynamics, and thus the spread of diseases caused by whitefly‐transmitted viruses. To date, however, host selection behaviour in B. tabaci has received little attention. Studies reported herein were conducted to determine if there were differences in rates of oviposition and offspring survival when adult B. tabaci were exposed to two different host plant species. There was no significant difference between oviposition rates on lettuce, Lactuca sativa L., and cantaloupe, Cucumis melo L., however, offspring survival was significantly greater on cantaloupe than lettuce. When given a choice, B. tabaci initially entered lettuce plots more frequently than cantaloupe plots, despite the fact that offspring survival rates were higher on cantaloupe. Within several days however, a greater number of whiteflies were trapped within cantaloupe plots compared to lettuce plots, suggesting movement or dispersal from lettuce plots into cantaloupe plots. In another dispersal study designed to measure leaving times, whiteflies reared on a particular host plant were more reluctant to leave that host than to leave other plant species tested. These results suggest that the host‐plant upon which B. tabaci has been reared may play a more important role in subsequent host selection than does the potential suitability of the host with respect to offspring survival. Zur Wirtspflanzenwahl von Bemisia tabaci (Gennadius) (Hom., Aleyrodidae) unter Gewächshausbedingungen Bemisia tabaci (Gennadius) ist in tropischen und subtropischen Gebieten der Erde von bedeutender wirtschaftlicher Wichtigkeit. Auf welche Weise Wirtspflanzen zur Nahrungsaufnahme und Eiablage ausgesucht werden, ist noch nicht genügend bekannt. Faktoren dieser Art beeinflussen die Wachstumsdynamik direkt und dadurch die Verbreitung von Viruskrankheiten, die durch B. tabaci übertragen werden. Das Verhalten, das zur Wahl der Wirte führt, wurde bisher wenig erforscht. Studien darüber untersuchten Unterschiede in der Eiablage und im Überleben der Nachkommenschaft von B. tabaci bei zwei verschiedenen Wirtspflanzen. Es gab keine signifikanten Unterschiede in der Eiablage zwischen Kopfsalat, Lactuca sativa L., und Honigmelone, Cucumis melo L.; die Überlebensrate der Nachkommen war bei Honigmelone aber höher als bei Kopfsalat. Wenn beides zur Auswahl stand, zog B. tabaci Salatbeete den Melonenbeeten vor, obwohl die Überlebensrate für Nachkommen in Melonen höher war. Innerhalb einiger Tage wurde eine größere Anzahl von B. tabaci in Melonenbeeten als in Salatbeeten gefangen; dies läßt Wanderung oder Dispersion von Salatbeeten in Melonenbeete vermuten. In einer anderen Dispersionsstudie wurde die Zeitspanne bis zum Verlassen gemessen. B. tabaci, die sich auf einer bestimmten Wirtspflanze entwickelt hatten, zeigten geringere Tendenzen, im Vergleich zu anderen getesteten Pflanzenarten diesen Wirt zu verlassen. Die Ergebnisse lassen die Vermutung zu, daß die Wirtspflanze, auf der B. tabaci aufwuchs, eine größere Rolle bei der Wahl des zukünftigen Wirtes spielt als eine mögliche Eignung für die Nachkommenschaft. 1991 Blackwell Verlag GmbH
• Wilson, F., & Brown, J. (1991). Inheritance of response to cotton leaf crumple virus infection in cotton. Journal of Heredity, 82(6). doi:10.1093/oxfordjournals.jhered.a111140
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  The inheritance of symptom development and symptom severity to the cotton leaf crumple virus (CLCV) in upland cotton, Gossypium hirsutumL, was investigated. Deltapine 90, which exhibits a severe reaction to CLCV infection, was crossed to Cedix, an asymptomaticcultivar originally from El Salvador. Parents, F1, F2, and backcross populations were exposed, as seedlings, to viruliferous whiteflies, Bemisia tabaci (Genn.), the insect vector of the virus, and scored routinely throughout the field season for presence and severity of cotton leaf crumple symptoms. Results indicated that factors controlling symptom expression were inherited as duplicate factors, and that the severe-symptom phenotype (genotype C1C1C2C2) was recessive to the asymptomatic phenotype (genotypes C1_C2_). This report is the first documented report of the inheritance of a viral disease in cotton. © 1991, The American Genetic Association.
• Poulos, B. T., Nelson, M. R., & Brown, J. K. (1990). Whitefly-Transmitted Geminiviruses of Tomato and Pepper in Arizona and Their Relationship to Geminiviruses in Florida and in Mexico. Vegetable Report.
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  Whiteflytransmitted geminiviruses, which cause serious diseases of tomato and pepper crops, have become increasingly important pathogens in the fringe temperate and subtropical agricultural regions of the United States and Mexico (Brown, 1988) during the 1980s. These virus diseases have a negative impact on fruit quality, and significantly reduce yields in most commercial tomato and pepper varieties currently grown. Millions of dollars have been lost as a result of geminivirus infections in tomatoes in the U.S. alone.
• BROWN, J., Brown, J. K., NELSON, M., & Nelson, M. R. (1989). Characterisation of watermelon curly mottle virus, a geminivirus distinct from squash leaf curl virus. Annals of Applied Biology, 115(2), 243-252. doi:10.1111/j.1744-7348.1989.tb03383.x
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  Purified preparations of watermelon curly mottle virus (WCMoV), a whitefly‐transmitted geminivirus, contained dimeric or geminate particles of 20 times 30 nm and the virus was transmissible by mechanical means. Virus yields ranged from 100–150 μg/100 g leaf tissue. Purified preparations exhibited a typical nucleoprotein absorbance profile with a maximum absorbance at 258 nm, and A280 / A260 ratio of 0.61–0.64. Infectivity was associated with two light‐scattering, virus‐containing bands following sucrose density gradient centrifugation. The viral capsid protein was resolved as a doublet by SDS‐PAGE. The estimated mol. wts of the two bands within the doublet were 29 100 (±1550) and 27 733 (±1550), respectively. DNA isolated from virus particles was resolved by gel electrophoresis into two circular single‐stranded DNA bands of approximately 2.6 to 2.7 kb. The two bands are believed to represent the individual components of a bipartite genome, characteristic of previously described whitefly‐transmitted geminiviruses. Copyright © 1989, Wiley Blackwell. All rights reserved
• Nelson, M. R., Matejka, J. C., & Brown, J. K. (1989). Use of Stylet Oil to Slow the Spread of Lettuce Infectious Yellows Virus. Vegetable Report.
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  Weight (in grams) of individual heads could be correlated with time of infection in that the lowest weights and marketability ratings occurred in plants infected earliest in the season. Whether they were front treated or untreated plots, marketable heads weighed an average of 784 grams; unmarketable heads weighed 491 grams. The key difference is that, on the average, five marketable heads of lettuce were in the oiltreated plots for every three in the untreated plots.
• Ray, D. T., Ray, D. T., Mcgrady, J., Mccreight, J. D., & Brown, J. K. (1989). Resistance in Cultivated and Wild Lettuce to Lettuce Infectious Yellows Virus. Vegetable Report.
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  In 1988, Arizona's earlyseason lettuce crop was plagued by disease and insect problems, both intensified by unseasonably high temperatures. In the western Arizona production area, an epidemic of lettuce infectious yellows (LIY) resulted in serious economic losses to growers. The yellows disease is incited by the LIY virus (LIYV), a plant virus transmitted by the sweet potato whitefly IBemisia tabaci (Gene.)]. Disease symptoms in lettuce include stunted growth, rolling yellowing and /or reddening of infected leaves; necrotic lesions appear at or near the leaf margins at latter stages of the disease. LIYV has a wide host range which increases the difficulty of isolating lettuce fields from LIYV infected or whitefly -infested fields; also, whiteflies are resistant to insecticides. Therefore, host plant resistance appears to be the most promising means of reducing losses due to this disease. To initiate a breeding program, commercial lettuce cultivars and breeding lines (Lactuca sativa L.), and related, cross -breeding wild lettuce species (L. serriola L. and L. saligna L.) were screened for resistance to LIYV in the western Arizona production area using natural inoculation by residence whiteflies.
• Brown, J. K., Fairbanks, D. J., & Smith, S. E. (1988). Inheritance of large mitochondrial RNA's in alfalfa.. TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik, 76(4), 619-22. doi:10.1007/bf00260917
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  Several large RNA molecules that migrated to electrophoretic positions ranging from 1.7-10 kb were observed in preparation of alfalfa (Medicago sativa) mitochondria. F1 progenies inherited the RNA's from both maternal and paternal parents (Fig. 1). Treatment of intact mitochondria with RNase A failed to remove the RNA's, indicating that they were contained within an RNase impermeable compartment. Further purification of mitochondria in linear sucrose gradients failed to separate the RNA's from mitochondria. Transmission electron microscopic examination of sucrose gradient purified mitochondria revealed that mitochondria were free of contamination by virus-like particles, indicating that the RNA's were contained within the mitochondrion. Biparental inheritance of large mitochondrial RNA's in alfalfa provides evidence that mitochondria are inherited biparentally in this species.
• Brown, J. K., & Nelson, M. R. (1984). Geminate particles associated with cotton leaf crumple disease in Arizona.. Phytopathology, 74(8), 987-990. doi:10.1094/phyto-74-987

Proceedings Publications

• Brown, J. K., Chingandu, N., Cho, M., Gomez, M. A., Jones, J., Pham, J., Staskawicz, B. J., & Zhang, E. (2019, July). CRISPR/Cas9-mediated targeting of Cacao swollen shoot virus DNA. In IS-MPMI XVIII Congress, Glasgow, Scotland..
• Brown, J. K. (2018, Summer). Molecular genomic diversity of previously undescribed cacao swollen shoot badnaviruses in Nigeria. In 2017 International Symposium on Cocoa Research, T3-Pests and Diseases.
• Brown, J. K. (2018, Summer). Variable detection of Cacao swollen shoots disease-associated badnaviruses by PCR amplification. In 2017 International Symposium on Cocoa Research, T3-Pests and Diseases.
• Brown, J. K., & Idris, A. M. (2007). Genetic diversity of Cotton leaf crumple virus in the Western Hemisphere.. In Proceedings of the International Cotton Conference Lubbock, Texas 2007.
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  Cotton leaf crumple virus (CLCrV) a New World begomovirus of cotton and malvaceous weeds was detected in cotton, kenaf and cheeseweed exhibiting leaf crumple and stunting symptoms collected from filed in Guatemala, Mexico, and the US (AZ, CA and TX). A fragment containing the coat protein (CP) was amplified, cloned and sequenced. Phylogenetic analysis of the CP nucleotide sequence placed the CLCrV isolates in a clade containing Sida golden mosaic Costa Rica virus. The analysis partitioned the CLCrV complex into two groups, constituting geographically isolated genotypes. One genotype, the west coast, was identified in Arizona, California, Mexico and Guatemala, while the second genotype was identified in Texas. Although, the genotype from Texas induces similar phenotype in cotton and is most closely related to the west coast genotype, it represents an example of begomovirus genotype in the brink of differentiation into a new species.
• Dennehy, T. J., Degain, B. A., Harpold, G., Brown, J. K., Byrne, F. J., Morin, S., & Nichols, R. L. (2006). First New World report of Q biotype of Bemisia tabaci (Gennadius) reveals high levels of resistance to insecticides.. In RPM Newsletter, 5, 18-19.
• Musser, R. O., Cipollini, D. F., Hum-Musser, S. M., Williams, S. A., Brown, J. K., & Felton, G. W. (2005). Evidence that the caterpillar salivary enzyme glucose oxidase provides herbivore offense in solanaceous plants. In Archives Insect Biochem Physiol, 58, 128-137.
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  The insect salivary enzyme glucose oxidase (GOX) can inhibit wound-inducible nicotine production in tobacco, Nicotiana tabacum. We examined whether salivary gland extracts of Helicoverpa zea lacking active GOX could still suppress nicotine in tobacco, Nicotiana tabacum, and whether GOX could suppress wound-inducible defenses of another Solanaceous plant, tomato Lycopersicon esculentum. Tobacco leaves were wounded with a cork borer and treated with water, salivary gland extracts with active GOX (SxG), or salivary gland extracts with inactive GOX (SxI). After three days, leaves treated with SxG had significantly less nicotine than all other wounded treatments. Neonates that fed on the terminal leaves of tobacco plants treated with SxG had significantly higher survival than neonates that fed on leaves treated with either SxI or water. This evidence supports the assertion that GOX is the salivary factor responsible for the suppression of tobacco plant nicotine production by H. zea saliva. Results for the NahG tobacco plants, which lack salicylic acid (SA) due to a transgene for bacterial SA hydroxylase, indicate that suppression of nicotine by GOX does not require SA. However, tobacco leaves that were wounded and treated with SxG had significantly higher levels of the SA-mediated PR-1a protein than leaves treated with SxI or water. Leaves of tomato plants wounded with scissors and then treated with SxG had trypsin inhibitor levels that were moderately lower than plants wounded and treated with purified GOX, water, or SxI. However, all the wounded tomato leaves irrespective of treatment resulted in lower caterpillar growth rates than the non-wounded tomato leaves. Glucose oxidase is the first insect salivary enzyme shown to suppress wound-inducible herbivore defenses of plants. © 2005 Wiley-Liss, Inc.
• Musser, R. O., Kwon, H. S., Williams, S. A., White, C. J., Romano, M. A., Holt, S. M., Bradbury, S., Brown, J. K., & Felton, G. W. (2005). Evidence that caterpillar labial saliva suppresses infectivity of potential bacterial pathogens. In Arch. Insect Biochem. Physiol., 58, 138-144.
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  Salivary enzyme, glucose oxidase (GOX) from the caterpillar Helicoverpo zeo, catalyzes the conversion of glucose to gluconic acid and hydrogen peroxide. Because hydrogen peroxide has well-known antimicrobial properties, we examined whether caterpillar labial saliva could reduce the infectivity of bacterial pathogens. We examined the effects of caterpillar saliva on the growth of two bacteria species Serratia marcescens and Pseudomonas aeruginosa. Wells formed in LB agar contained a solution of salivary gland extract (Sx) and glucose, GOX and glucose, Sx only, GOX only, or glucose only. After 18 h of incubation, the diameter of cleared bacteria was measured. Wells treated with only GOX, Sx, or glucose showed no measurable area of clearing, while wells treated with GOX with glucose or Sx with glucose had considerable clearing. To determine if saliva could provide protection to caterpillars in vivo, a surgery was performed on caterpillars that prevented the secretion of labial saliva. Caterpillars were fed a diet containing either no added bacteria or treated with high levels of S. marcescens or P. aeruginosa. Caterpillars that could not secrete saliva had significantly higher levels of mortality when feeding on diet treated with either bacterium than caterpillars that could secrete saliva when feeding on equal levels of bacteria-treated diet. Our evidence demonstrates for the first time that insect saliva in situ can provide protection against bacterial pathogens and that the salivary enzyme GOX appears to provide the antimicrobial properties. © 2005 Wiley-Liss, Inc.

Presentations

• Brown, J. K. (2019, March 10-15). Psyllid-Ca.Liberibacter interactions involved in the circulative, propagative transmission pathway: molecular and cellular interfaces. Joint International Citrus Virology Conference and International Research Citrus Workshop-HLB. Riverside CA: Citrus Virology and International Citrus Workshop.
• Brown, J. K. (2019, May). Functional genomics of whitefly vector-begomovirus interactions. APS-Caribbean Division annual meeting, joint w/ CENSA III International Seminar on Animal and Plant Health (SISA). Varadero, Cuba: APS-Caribbean division.
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  Invited Plenary presentation, whitefly virus-vector interactions
• Brown, J. K. (2019, May). High throughput phenotyping and -omics tools to study cacao diseases. (i) Cacao swollen shoot virus status in West Africa; (ii) Molecular detection platforms for CSSD. Toward sustainable cacao production in Western Africa. Kenema, Sierra Leon: IITA, Ibadan Nigeria.
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  Invited workshop presentations (2)
• Brown, J. K. (2019, National Plant Diagnostics Fifth National MeetingApril 15-18). New Developments in Taxonomy of Plant Viruses. National Plant Diagnostics Network - Fifth National Meeting Indianapolis, IN. Indianapolis, IN: National Plant Diag Network.
• Brown, J. K. (2019, November 11-14). Emergent vector-borne DNA viruses of cotton and cacao – possible risks and routes of global spread. Joint Annual Entomological Society of America / Entomological Society of British Columbia Meeting. Vancouver, BC: MARS and USDA-ARS Miami.
• Brown, J. K. (2019, October 21-22). Cacao swollen shoot virus: update on CSSV research on viral genomic diversity and molecular detection platforms. Cacao Working Group. Accra, Ghana: MARS.
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  invited presentation
• Brown, J. K. (2019, October 29-31). Brown, J.K. 2019. Genomic variability and evolutionary considerations of badnaviruses associated with cacao swollen shoot disease. International Advances in Plant Virology. Rome Italy: MARS, USDA-ARS Miami.
• Brown, J. K. (2019, Sept 26-27). Dynamics of the whitefly vector associated with the cotton leaf curl outbreak. 2nd Sino-Pak International Conference on Innovations in Cotton Breeding and Biotechnology. Multan, Pakistan: Cotton Incorporated and Local conference grant sponsorship from HEC, Pakistan.
• Brown, J. K. (2019, September). Biopesticidal dsRNA therapy for psyllid mortality and abatement of vector-mediated CLas transmission. Invited Seminar. Hattiesburg, MS: University of Southern Mississippi.
• Brown, J. K. (2018, April). Circulative, propagative transmission up close: Ca. Liberibacter spp. exploits endo/exocytosis and cytoskeleon remodeling pathways in the psyllid vector.. CALS Frontiers in Life Science Research Seminar. Univerity of Arizona: CALS Administration.
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  Invited lecture
• Brown, J. K. (2018, July). Cacao Swollen Shoot Virus: what we know and don’t know after 100 years. International Congress of Plant Pathology. Boston, MA: International Congress of Plant Pathology.
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  Invited Symposium Presentation
• Brown, J. K. (2018, July). Classification and characterization of plant viruses identified by metagenomics approaches. Sequence based taxonomies for plant pathogens symposium. International Congress of Plant Pathology. Boston, MA: International Congress of Plant Pathology.
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  Invited Symposium Presentation
• Brown, J. K. (2018, June). Diseases caused by arthropod-transmitted virus and Liberibacter in southwestern desert crops. Progressive Farmers. Blythe, CA: UC-California-Riverside County Agriculture and Natural Resources, Coop Extension.
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  Invited presentation
• Brown, J. K. (2018, June). Swollen shoot disease of cacao: the tale of an exotic plants’ fate in a foreign land. UBRP Summer Program. Univerity of Arizona: Undergraduate Biology Research Program.
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  Invited lecture, summer UBRP
• Brown, J. K. (2018, March). CSSD Badnavirus discovery and characterization to inform molecular detection. Pest and Diseases Workshop, MARS. Miami, FL: MARS and USDA-ARS cacao researchers.
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  Invited presentation
• Brown, J. K. (2018, March). Viruses of grapevines: Vectors and diseases. Viticulture Workshop, University of Arizona. Benson, AZ: Extension.
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  Invited presentation
• Brown, J. K. (2018, November). Emergent vector-borne DNA viruses of cotton and cacao – possible risks and routes of global spread. Joint Annual Entomological Society of America, Entomological Society of British Columbia. Vancouver, BC: Entomological Society of America.
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  Invited Symposium Presentation
• Brown, J. K. (2018, throughout the year). 11 Professional meeting abstracts (9-oral presentations, 2 posters). Professional meetings (Beltwide Cotton Conference, Plant and Animal Genome Conference, Amer Phytopath Soc, Sino-Pakistan Cotton Biotechnology, Entomol Soc Amer,13th Ann Seq, Finishing, Anal Future-Vampiro genome seq)listed above.
• Brown, J. K., Avelar, A. S., & Schuch, U. (2018, June). Cause of witches broom on blue palo verde. Desert Horticulture Conference. Star Pass Marriott Hotel: UA Extension.
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  Invited presentationA.S. Avelar, presenter
• Brown, J. K. (2017, August). Molecular diagnostics for exotic leaf curl begomovirus-betasatellites undergoing diversification and expansion. America Phytopathological Society, Annual meeting Abstract. San Antonio, TX.
• Brown, J. K. (2017, June). Psyllid vector-Ca. Liberibacter interactions at cellular and molecular interfaces. Third Hemiptera-Plant Interactions Symposium. Madrid, Spain: Third Hemiptera-Plant Interactions Symposium.
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  Invited Speaker
• Brown, J. K. (2017, March). Psyllid vector-Liberibacter interactions at cellular and molecular interfaces. Fifth Intern’l Res. Conf. on HLB Abstract. Orlando, FL.
• Brown, J. K. (2016, April 20). Insect vectors of plant and fastidious bacterial pathogens in Arizona. Maricopa County Master Gardeners - Science Education. Maricopa Co. Extension Center, Phoenix, AZ.: Extension (Kelly Young).
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  2.5 hours lectures on plant viruses, vectors, management in gardens
• Brown, J. K. (2016, April). A cumulative model for Liberibacter invasion and circulation based on electron microscopy, functional genomics, proteomics, and yeast-2-hybrid analyses. Pacific Branch-ESA. Honolulu Hawaii: Symposium Animal and Plant Vector Biology: Addressing Old Questions with New Technologies (organizer; speaker).
• Brown, J. K. (2016, August). Badnaviruses associated with Theobroma cacao L. in West Africa and Trinidad. Mars Research Committee meeting. UC-Davis, Davis CA: MARS and UC-Davis.
• Brown, J. K. (2016, January). Citrus greening disease and future prospects for lemons in Arizona. Community Culinary Kitchen cooking evening. Tucson, AZ: Community Culinary Kitchen dinner speaker: Food theme-lemons.
• Brown, J. K. (2016, January). Cocao swollen shoot virus: Virome-diagnostic development for a re-emergent, mealybug-transmitted virus spreading in West Africa.. Plant and Animal Genome Conference. San Diego, CA: PAG.
• Brown, J. K. (2016, June). An emerging tale of elusive badnaviruses associated with Theobroma cacao L. in West Africa.. International Research Teleconference. Miami FL/Redding UK, UC-Davis: USDA-ARS/MARS Quarantine Committee.
• Brown, J. K. (2016, June). An emerging tale of elusive badnaviruses infecting cacao in the Eastern Caribbean and East Africa.. Frontiers in Science and Technology for Cacao Quality, Productivity and Sustainability.. College Park, PA: Penn State University.
• Brown, J. K. (2016, June). Next-generation diagnostics: new prospects for etiological and epidemiological studies of plant viruses.. KEYNOTE Speaker: 13th International Plant Virus Epidemiology Symposium. Avignon, France: IPVE.
• Brown, J. K. (2016, June). Parallel proteome-transcriptome enabled interrogation of whitefly proteins involved in begomovirus transmission. Invited Seminar. Beijing, China: Chinese Acad. Sci. Inst. Vegetables & Flowers.
• Brown, J. K. (2016, June). The cotton leaf curl pandemic-A diagnostics dilemma. Invited seminar. Guangzhou, China: Guangdong Academy of Agricultural Sciences -Plant Protection Unit.
• Brown, J. K. (2016, March). Spreading the Heat: Insect transmitted pandemic-associated pathogens concurrent with changing climate. Fourth NPDN National Meeting. Washington D.C.: Symposium. Advancing Diagnostics for Emerging Pathogens and Pests Affected by Gloabal Trade and Climate Change.
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  Celebration of 15 years of the National Plant Diagnostic Network
• Brown, J. K. (2016, November). Cacao swollen shoot virus in West Africa comprises a complex of species with variable genome and conserved protein domain arrangements. Regional Symposium: Next Generation Cocoa Research for West and Central Africa. Ibadan, Nigeria: IITA.
• Brown, J. K., & Chingandu, N. (2016, March). Cacao swollen shoot virus-an emergent viral pathogen of the chocolate plant.. Undergraduate Plant Science Club speaker. UA Shantz Bld: Plant Science Club.
• Brown, J. K., & Fisher, T. (2016, Sept). Psyllid vector-Liberibacter interactions at cellular and molecular interfaces. Huanglongbing Symposium. Orlando, FL: International Congress of Entomology.
• Brown, J. K., & Schuch, U. K. (2016, June). Palo verde witches broom. Desert Horticulture Annual Meeting. Tucson: UA.
• Schuch, U. K., & Brown, J. K. (2016, June). Palo Verde Broom Disease. Desert Horticulture Conference. Tucson: UA Cooperative Extension.
• Brown, J. K. (2013, April). Zebra chip diease. Evidence for Ca. Liberibacter invasion, adherence, and motility in the psyllid vector. Zebra Chip Symposium. Pacific Branch ESA. Coeur d’Alene, ID.
• Brown, J. K. (2015, December). Prospects for isothermal field detection of emerging viral pathogens of cacao, cotton, and cowpea. AGDIA Invited seminar. Elkhart, IN.
• Brown, J. K. (2015, February). Invited Presentation: Re-emergence of Cacao swollen shoot virus in West Africa: evidence for extreme diversity and a possible virus complex. Insect Pests and Diseases of Cacao Workshop. Orlando, FL.
• Brown, J. K. (2015, February). Invited Seminar: Application of RNAi to interfere with insect transmission of citrus greening disease. UF Whitney Marine Biosciences Laboratory. Augustine, FL.
• Brown, J. K. (2015, January). Invited Workshop: Citrus greening: biofilms and yellow dragons. USDA-APHIS Workshop. Phoenix, AZ.
• Brown, J. K. (2015, January). Invited Workshop: Cocao swollen shoot virus: Virome-diagnostic development for a re-emergent, mealybug-transmitted virus spreading in West Africa. . Cacao Genome Workshop, Plant & Animal Genome Conference Symposium. San Diego, CA.
• Brown, J. K. (2015, July/August). Seed transmission of vector borne pathogens. Assessment of detection methods and the threat of Candidatus Liberibacter in seed and other propagative plant materials. American Phytopathological Society Seminar. Pasadena, CA.
• Brown, J. K. (2015, June). : Identification and characterization of a cyanobacterial pathogen of Chlorella species in the ARID raceway: Vampirovibrio chlorellavorus. CICY, Invited Seminar. Cancun, Qunitana Roo, Mexico.
• Brown, J. K. (2015, March). Cotton leaf curl virus complex: diversification and evolution of the resistance-breaking Burewala strain following release of a Multan-resistant variety. Invited Seminar, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences. Ghangzhou China.
• Brown, J. K. (2015, March). Parallel proteome-transcriptome enabled interrogation of whitefly effectors of begomovirus transmission. Invited Seminar, Institute of Vegetables and Flowers, Chinese Academy of Sciences. Beijing, China.
• Brown, J. K. (2015, November). A global perspective on badnaviruses causing diseases of cacao. Symposium and Panel Discussion, Cacao Research Center and Gene Bank. Port of Spain, Trinidad.
• Brown, J. K. (2015, November). The Bemisia tabaci sibling species group: taxonomic conundrum and successful virus vector - a history and perspective. Invited Seminar: Plant Protection Unit, University of West Indies. Port of Spain, Trinidad.
• Brown, J. K. (2015, October). Organizer and Speaker; Historical overview and future outlooks for the AZPDN. 10th Aniversary Meeting, AZ-Plant Diagnostic Network, UA Campus-McClelland. Tucson, AZ.
• Brown, J. K. (2014, Fall). Functional genomics of the whitefly Bemisia tabaci (B biotype) begomovirus transmission and dsRNA silencing of candidate genes expressed in the whitefly Bemisia tabaci (B biotype) gut.. Workshop on whitefly genomics Dar es Salam, Tanzania.. International Institute for Tropical Agriculture,: USDA-USAID.
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  Functional genomics of the whitefly Bemisia tabaci (B biotype) begomovirus transmission and dsRNA silencing of candidate genes expressed in the whitefly Bemisia tabaci (B biotype) gut. USDA-USAID Focus on whitefly. International Institute for Tropical Agriculture, Dar es Salam, Tanzania. Oct 20-23, 2014.
• Brown, J. K. (2014, Fall). Psyllid transcripts with potential involvement in Ca. Liberibacter invasion and propagative transmission: Toward RNAi mediated abatement of citrus greening and zebra chip diseases.. Departmental Seminar. Microbiology Dept, UA.
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  Invited seminar: Psyllid transcripts with potential involvement in Ca. Liberibacter invasion and propagative transmission: Toward RNAi mediated abatement of citrus greening and zebra chip diseases. Vet-Science Microbiology Seminar, University of Arizona Nov 10, 2014.
• Brown, J. K. (2014, Fall). Re-emergence and rapid spread of Cacao swollen shoot virus: greater than expected genomic variability.. Cacao Net On Farm Conservation and America’s Cacao breeder’s Working Group Meetings. Turrialba, Costa Rica: CATIE.
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  Re-emergence and rapid spread of Cacao swollen shoot virus: greater than expected genomic variability. Cacao Net On Farm Conservation and America’s Cacao breeder’s Working Group Meetings, Oct 24-31, 2014.
• Brown, J. K. (2014, Fall). Re-emergence of Cacao swollen shoot virus: unexpected genomic variability.. USDA-World Cacao Foundation Workshop.. Miami, FL: USDA-ARS Tropical Horticuture Research Laboratory.
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  Invited Presentation: Re-emergence of Cacao swollen shoot virus: unexpected genomic variability. USDA-World Cacao Foundation Workshop. Miami, FL Dec 4, 2014.
• Brown, J. K. (2014, January). Exploring the diversity of Cacao swollen shoot virus an emergent badnavirus of Theobromus cacao endemic in West Africa.. Plant and Animal Genome meeting-Cacao genome project. San Diego, CACacao genome project committee.
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  Invited Workshop: Exploring the diversity of Cacao swollen shoot virus an emergent badnavirus of Theobromus cacao endemic in West Africa. Invited Presentation. Plant and Animal Genome meeting-Cacao genome project. San Diego, CA January 9-13, 2014.
• Brown, J. K. (2014, Spring 2014). Molecular analysis of the Bemisia tabaci sibling species group: causal role in the Severe African cassava mosaic virus pandemic.. Entomological Society of America, Pacific Branch meeting. Tucson Arizona: ESA-PB.
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  Symposium: Molecular analysis of the Bemisia tabaci sibling species group: causal role in the Severe African cassava mosaic virus pandemic. Entomological Society of America, Pacific Branch meeting, Tucson, AZ April 8, 2014.
• Brown, J. K. (2014, Spring). Begomovirus diversity, phylogenetic and population genetics in cultivated and uncultivated plant ecosystem in Pakistan. Plant Pathology Conference. Lahore, Pakistan: University of Punjab-Lahore.
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  Plenary: Begomovirus diversity, phylogenetic and population genetics in cultivated and uncultivated plant ecosystem in Pakistan. Plant Pathology Conference, University of Punjab-Lahore, May 22-24, 2014.
• Brown, J. K. (2014, Spring). Emergent and Invasive Psyllid-Liberibacter complexes. Western Plant Board 95th Annual Conference.. Tucson Arizona: AZ Department of Agriculture.
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  Emergent and Invasive Psyllid-Liberibacter complexes. Western Plant Board 95th Annual Conference. Tucson, Arizona. March 24-27, 2014.
• Brown, J. K. (2014, Spring). Mechanisms of begomovirus expansion inadvertent selection of resistance-breaking viruses in a center of extreme diversity.. Invited Seminar, College of Agriculture. Faisalabad, Pakistan: Pakistan Agricultural University.
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  Invited College Seminar: Mechanisms of begomovirus expansion inadvertent selection of resistance-breaking viruses in a center of extreme diversity. Pakistan Agricultural University, Faisalabad, Pakistan. May 25, 2014.
• Brown, J. K. (2014, Summer). About Plant Viruses. Course lecture. Prescott College.
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  Invited lecture: About Plant Viruses. Prescott College, Prescott, AZ. June 24, 2014.
• Brown, J. K. (2014, Summer). Biotypes and phylogenetic biology of the Bemisia tabaci sibling species complex.. Whitefly taxonomy workshop. Rio Piedras, Puerto Rico.. Rio Piedras, PR: University of Puerto Rico.
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  Invited Presentation: Biotypes and phylogenetic biology of the Bemisia tabaci sibling species complex. Whitefly taxonomy workshop. Rio Piedras, Puerto Rico. August 31, 2014.
• Brown, J. K. (2014, Summer). Ca. Liberibacter solanacearum: a psyllid-transmitted, endemic and exotic, emergent fastidious prokaryote. APS-Pacific Division Meeting. Vector Symposium. Bozeman, MT: APS-Pacific Division.
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  Symposium: Ca. Liberibacter solanacearum: a psyllid-transmitted, endemic and exotic, emergent fastidious prokaryote. Plant Virus-Vector Complexes in the Western US, APS-Pacific Division Meeting. Vector Symposium, Bozeman, MT July 8-11, 2014.
• Brown, J. K. (2014, Summer). Comparative transcriptome analysis of Asian citrus and Potato psyllids harboring or free of Ca. Liberibacter: putative effectors involved in adhesion, immunity, nutrition, and endo-exocytosis-like processes.. Symposium Presentation, CIBE. Guayaquil, Ecuador: CIBE.
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  Comparative transcriptome analysis of Asian citrus and Potato psyllids harboring or free of Ca. Liberibacter: putative effectors involved in adhesion, immunity, nutrition, and endo-exocytosis-like processes. Invited Symposium Presentation, CIBE 2014 Guayaquil, Ecuador June 9-12, 2014.
• Brown, J. K. (2014, Summer). Insect vector-borne viruses of legumes in the Desert Southwest: a pipeline for producing virus-free bean seed from infected germplasm seed.. Course lecture. Prescott College.
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  Invited lecture: Insect vector-borne viruses of legumes in the Desert Southwest: a pipeline for producing virus-free bean seed from infected germplasm seed. Prescott College, Prescott, AZ. June 24, 2014.
• Brown, J. K. (2014, Summer). Re-emergence of Cocao swollen shoot virus genomic variability and next steps to design diagnostics to support breeding, tree replacement, and molecular epidemiological studies in West Africa. Workshop on Cacao. Miami, FL: USDA-ARS Tropical Horticuture Research Laboratory.
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  Seminar: Re-emergence of Cocao swollen shoot virus genomic variability and next steps to design diagnostics to support breeding, tree replacement, and molecular epidemiological studies in West Africa. USDA-ARS Tropical Horticuture Research Laboratory, Miami, FL June 19, 2014.
• Brown, J. K. (2013, April). Characterization of vein-greening disease of tomato and psyllid vector in Arizona. Invasive species working group. Portland, OR.
• Brown, J. K. (2013, April). Cotton leaf curl disease Recovery Plan. National Plant Disease Recovery System. Arlington, VA.
• Brown, J. K. (2013, April). Psyllid-Liberibacter complexes: Emerging vector-pathogens. National Plant Disease Recovery System. Arlington, VA.
• Brown, J. K. (2013, August). Cacao swollen shoot virus (CSSV)diagnostics and genetic diversity. USDA-ARS Subtropical Horticultural Research Station. Miami CSSV.
• Brown, J. K. (2013, August). Mechanisms of Begomovirus Expansion-The panacea of host resistance genes: inadvertent selection of resistance-breaking viruses in a center of extreme diversity. APS-MSA Meeting Symposium. Austin, TX.
• Brown, J. K. (2013, January). Same vehicle, different engine: the dynamics of Bemisia tabaci populations driving Cassava virus disease pandemics in sub-Saharan Africa (Legg et al). 12th International Plant Virus Epidemiolology Symposium. Arusha, Tanzania.
• Brown, J. K. (2013, January). Whitefly Bemisia tabaci and effects on virus disease epidemiology in contrasting study systems in Central America and sub-Saharan Africa. IPM CRSP Global Themes Symposium, 12th International Plant Virus Epidemiology meeting. Arusha, Tanzania.
• Brown, J. K. (2013, July). Begomovirus diversity, phylogeography, and population genetics in cultivated and uncultivated plant ecosystems in Pakistan. . Biodiversity and Integrated Pest Management: Working Together for a Sustainable Future. Manado, North Sulawesi, Indonesia.
• Brown, J. K. (2013, July). Cotton leaf curl virus disease complex: a potential risk to world cotton production. Cotton Production Institute. Urumqi, China.
• Brown, J. K. (2013, July). Cotton leaf curl virus disease complex: potential risk to world cotton production. Department of Vegetable Science, Punjab Agricultural University. Ludhiana, India.
• Brown, J. K. (2013, March). Biofilms and yellow dragons. College of Agriculture, Spring Awards Luncheon. Featured Speaker. University of Arizona, Tucson, AZ.
• Brown, J. K. (2013, May). Plant viruses of alfalfa and legume crops. Invited Departmental Seminar, King Saud University. Riyadh, Saudi Arabia.
• Brown, J. K. (2013, November). A highly divergent begomovirus clade whose members are host-restricted to the Convolvulaceae, and extant in wild and cultivated species in the Eastern and Western Hemispheres. , Invited Presentation, 7th International Geminvirus Symposium, 5th International ssDNA Comparative Virology Workshop. Hangzhou, China.
• Brown, J. K. (2013, November). Diversity and distribution of Cacao swollen shoot virus in wild host plants and mealybugs in Cote d’Ivoire (Brown and AKA Romain, presenter). National CSSV Planning Meeting. Bassam, Cote d’Ivoire.
• Brown, J. K. (2013, November). The whitefly Bemisia tabaci sibling (cryptic) species group- a taxonomic conundrum. Invited Seminar. Chinese Academy of Sciences, Institute of Vegetables and Flowers. Beijing, China.
• Brown, J. K. (2013, September). Introduction to Phylogenetic Analysis. Workshop Lecture, King Saud University. Riyadh, Saudi Arabia.
• Brown, J. K. (2013, September). Mechanisms of begomovirus expansion: the panacea of host resistance genes and selection of resistance-breaking viruses in a center of extreme diversity. College of Agriculture Seminar, King Saud University. Riyadh, Saudi Arabia.
• Brown, J. K. (2013, September). Plant virus evolution. The National Science Plan Workshop, King Saud University. Riyadh, Saudi Arabia.
• Brown, J. K. (2011, April). Liberibacter solanacearum and the potato psyllid: an unusual emergent bacterial-hemipteran vector complex in potato and tomato. Seminar. Ft Collins, CO: Colorado State University.
• Brown, J. K. (2011, August). Management of Insect-Transmitted Plant Virus Diseases in the Tropics : Whitefly vector populations in relation to virus ecology and management. American Phytopathological Society National meeting. Honolulu Hawaii: American Phytopathological Society.
• Brown, J. K. (2011, August). New generation sequencing for integrating plant breeding and transgenic protection to managing cotton-infecting begomoviruses. Lahore and Cotton Research Institute. Multan, Pakistan: University of Punjab.
• Brown, J. K. (2011, December). Whitefly-transmitted viruses of melons in the subtropics. Research Station visit and presentation. Fortaleza, Brazil.
• Brown, J. K. (2011, January). First Detector Training. First Detector Training. Sierra Vista, AZ: Cochise County Master Gardeners.
• Brown, J. K. (2011, January). First Detector Training. First Detector Training. Yuma County Extension Office: Yuma County Master Gardeners,.
• Brown, J. K. (2011, June). Progress on the whitefly and psyllid transcriptomes. 7th Meeting of the International Aphid Genomics Consortium. Kansas City, MO: International Aphid Genomics Consortium.
• Brown, J. K. (2011, March). From biotypes and phylogenetic biology, to newgeneration sequencing technologies to unravel the mysteries of the Bemisia tabaci sibling species complex. APS-Caribbean Division-Entomological Society Southern Division joint meeting. Puerto Rico: APS.
• Brown, J. K. (2011, November). Use of omic approaches to study transmission of plant pathogens. Transcriptomics to illuminate Ca. Liberibacter solanacearum- potato psyllid interactions. Entomol. Soc. of America National Meeting. Reno, NV: Entomol. Soc. of America.
• Brown, J. K. (2011, October). Historical overview and current status of the Bemisia tabaci sibling species group. Plant Protection Institute. Guangzhou, China: Guangdong Academy of Agricultural Sciences.

Poster Presentations

• Brown, J. K. (2019, Summer). We submitted eight meeting abstracts in 2019: grad students/post docs: presented 4 oral and 4 poster presentations. variousresearch grant support.
• Brown, J. K. (2017, November). Three previously known species, and two newly described species, Cacao red vein virus and Cacao red vein-banding virus, are associated with cacao swollen shoot disease in West Africa. International Symposium on Cocoa Research, Lima, Peru Abstract. Lima, Peru.

Reviews

• Brown, J. K. (2019. Chocolate under threat from old and new cacao diseases.(pp Phytopathology 109: 1331-1343). St Paul, MN.
• Brown, J. K. (2016. Review of the cultivation program within the national alliance for advanced biofuels and bioproducts.(pp DOI10.1016/j.algal.2016.11.021).
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  Lammers, P., Huesemann, M., Boeing, W., Anderson, D.B., Arnold, R.G., Bai, X., Bohle, M., Brown, L., Brown, J.K., Downes, M.C., Ge, Y., Holladay, J.E., Khopkar, A., Laur, P., Marrone, B.L., Mott, J.B., Nirmalakhandan, K., Ogden, K., Parsons, R., Polle, J., Ryan, R.D., Sayre, R.T., Seger, M., Selvaratnam, T., Thomasson, A., and Olivares, J.A. 2016. Review of the cultivation program within the national alliance for advanced biofuels and bioproducts. Algal Res. DOI10.1016/j.algal.2016.11.021
• Leke, W. K., Mignouna, D. B., & Kvarnheden, A. (2015. Begomovirus disease complex: Emerging virus diseases treat in vegetable production systems of West and Central Africa -A review.(pp 4:1 http://dx.doi.org/10.1186/s40066-014-0020-2).
• Brown, J. K. (2014. Begomovirus disease complex: Emerging virus diseases treat in vegetable production systems of West and Central Africa -A review. Agriculture and Food Security(p. 1). Agriculture and Food Security.
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  Leke, W., Mignouna, D.B., Brown, J.K., and Kvarnheden, A. 2015. Begomovirus disease complex: Emerging virus diseases treat in vegetable production systems of West and Central Africa - A review. Agriculture and Food Security 4:1. http://dx.doi.org/10.1186/s40066-014-0020-2. BioMed Central.

Creative Productions

• Brown, J. K. (2015. Webinar: Threat of Cowpea mild mottle virus —what we know and don’t know about this exotic virus.. American Phytopathological Society Scientific PresentationsUSDA. http://www.apsnet.org/publications/webcasts/scientificpresentations/Pages/Cowpeamildmottlevirus.aspx#play
• Brown, J. K. (2015. http://www.plantmanagementnetwork.org/edcenter/seminars/cotton/BegomovirusWhitefly/. APS On line webinar. Minneapolis, St Paul MN: American Phytopathological Society Scientific Presentations. http://www.apsnet.org/publications/webcasts/scientificpresentations/Pages/Cowpeamildmottlevirus.aspx#play
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  Webinar discussing the potential introduction of an exotic whitefly-transmitted plant virus introduction and the importance to soybean and bean crops in the US
• Brown, J. K. (2014. Webcast: Begomovirus-Whitefly Vector Complexes: Emerging Threats to Cotton-Vegetable Crop Biosecurity.. http://www.plantmanagementnetwork.org/edcenter/seminars/cotton/BegomovirusWhitefly/Plant Management Network, Crop Protection and Management Collection: Focus on Cotton. http://www.plantmanagementnetwork.org/edcenter/seminars/cotton/BegomovirusWhitefly/
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  WebCast- American Phytopathological Society Plant Management Network, Crop Protection and Management Collection: Focus on Cotton. Begomovirus-Whitefly Vector Complexes: Emerging Threats to Cotton-Vegetable Crop Biosecurity. Released November 18, 2014.

Others

• Brown, J. K. (2018, February). Cacao Swollen Shoot Virus. Radio Interview, Bill Buckmaster Show.
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  Radio Interview
• Brown, J. K. (2016, December). National Plant Disease Recovery System Recovery Plan: Cotton leaf curl virus complex. (Commissioned Revision). USDA-ARS Office of Pest Management Policy National Plant Disease Recovery System..
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  Brown, J.K. 2016. National Plant Disease Recovery System Recovery Plan: Cotton leaf curl virus complex. USDA-ARS Office of Pest Management Policy National Plant Disease Recovery System. http://www.ars.usda.gov/research/docs.htm?docid=14271 (2013; revised 2016).
• Brown, J. K., & Rodrigues, J. C. (2015, May 2015). National Plant Disease Recovery System Recovery Plan: Cowpea mild mottle virus complex.. USDA-ARS Office of Pest Management Website. http://www.ars.usda.gov/research/docs.htm?docid=14271
  More info

  Brown, J.K. and Rodrigues, J.-C. 2015. National Plant Disease Recovery System Recovery Plan: Cowpea mild mottle virus complex (now in revision to update from 2014 published version).
• Brown, J. K. (2014, May). National Plant Disease Recovery System Recovery Plan: Cotton leaf curl virus complex. USDA-ARS Office of Pest Management Policy National Plant Disease Recovery System. http://www.ars.usda.gov/research/docs.htm?docid=14271
• Brown, J. K. (2014, November). The program trains and mentors diverse students, visiting scholars, and post-doctoral associates representing many different countries. This provides them and other (US) members of the lab with a broad uWebcast: Understanding of different cultures and traditions, and creating opportunities for future collaboration and networking.. PUblished on Line: American Phytopathological Society. http://www.plantmanagementnetwork.org/edcenter/seminars/cotton/BegomovirusWhitefly/