Judith K Brown
- Professor, Plant Science
- Professor, BIO5 Institute
- Research Associate Professor, Entomology
- Professor, Entomology / Insect Science - GIDP
- Regents Professor, Plant Sciences
- Member of the Graduate Faculty
Dr. Judith K. Brown has dedicated her career to the study of vector-borne plant pathogens of global importance. Over the last 30+ years, she has tackled a number of challenging viral disease problems around the globe. She has visited, lectured, and studied emerging viral diseases in >65 countries. Her laboratory has hosted over 60 visiting scholars or graduate students from 30+ countries. Dr. Brown is best known for her groundbreaking research on begomoviruses and their whitefly vectors. She has characterized a large number of begomovirus species/strains and epidemiologies, pioneered detection/identification methods, and helped establish taxonomy and nomenclature for geminivirus classification. With respect to the whitefly vector, she has conducted research to test the hypothesis that Bemisia tabaci is a cryptic species, consistent with the observed widely variable differences within and between genetic variants, i.e. host range, habitat, and begomovirus transmission. Recently, at least five cryptic species have been delineated by nuclear genome sequence analyses. Research also involves elucidating the transmission pathway and begomovirus-gut/salivary gland interactions, and use of dsRNA/RNAi as a biopesticide for gene knockdown in insect vectors. Recently she has contributed importantly to the emerging pathosystem of psyllids and Ca. Liberibacter and the reemerging Cacao swollen shoot badnavirus complex. Her passion and commitment to international plant pathology has led to applied solutions that improve global food security.
Dr. Brown is Full Professor at The University of Arizona, Tucson in the School of Plant Sciences with a joint appointment in the Department of Entomology. She also holds an honorary appointment at Centro de Investigación Científica de Yucatán, Merida. Brown was born in Youngstown, Ohio and moved to Scottsdale, Arizona at an early age. She received her B. S. in Horticulture / Plant Pathology minor from Texas A & M University in 1979. For her M.S. degree she studied luteoviruses and aphid vector biology at Washington State University. Judy returned to Arizona and completed her Ph.D. at the University of Arizona where she was the first to study whitefly-transmitted viruses in Arizona, that coincidently emerged as a threat to the desert southwest as she began her graduate studies and early scientific career. Tucson remained her base with appointments as a post-doc (1985-1989) and Research Professor (1990-1999), ultimately joining the academic ranks in Plant Sciences as Associate Professor (1999), and advancing to Full Professor (2004). She has been recognized for her scholarly achievements as recipient of the Wellman Award, the Caribbean Division’s highest recognition for international contributions to plant pathology, as APS Fellow in 2011, and Fellow, American Association for the Advancement of Science Fellow in 2015. In 2019, she was awarded the College of Agriculture’s Faculty of the Year primarily for her international research and training contributions.
Brown has been globally integrated with her begomovirus-whitefly research and has worked on this system in more than 41 countries and she has logged 5 million air travel miles. Recently, this research has led Brown to Pakistan where she is leading efforts to characterize cotton leaf curl begomoviruses and the whitefly vector and endosymbiont populations that drive disease spread. She coordinates efforts to towards identifying sources of resistant germplasm and develop diagnostic tools (1994-1998; 2011-present). Successful outcomes requires expertise in the complexity of the system, and the associated viruses and associated betasatellites. In this area of research Brown has trained Ph.D.-level and young faculty scientists on country-supported fellowships from Burkina Faso, Cameroon, China, Cote d’Ivoire, Cyprus, Egypt, Ghana, Guatemala, India, Nigeria, Oman, Pakistan, Sweden, and Uganda, among others.
- Ph.D. Plant Pathology - Virology
- University of Arizona, Tucson, Arizona, United States
- WHITEFLY-TRANSMITTED VIRUSES OF THESOUTHWEST (PLANT, INSECT-TRANSMITTEDGEMINIVIRUSES)
- University of Arizona, Tucson, Arizona (2004 - Ongoing)
- Adjunct Professor
- Plant Protection Department, University of Puerto Rico, Rio Piedras, Fall 1995
- Vice President
- Caribbean Division-American Phytopathological Society, Summer 2019
- College of Agriculture, Research Faculty of the Year
- College of Agriculture and Life Sciences, Spring 2019
- Fulbright Specialist
- Fulbright Specialist Program, Fall 2017
- American Association for Advancement of Science, Fall 2015
- American Phytopathological Society, Summer 2011
- Honorary Professor
- CICY, Merida, Yucatán, Mexico, Winter 2012
- Partnership Award-National Plant Diagnostic Network
- USDA-NIFA Partnership Award, Fall 2010
- Wellman Award
- American Phytopathological Society-Caribbean Division, Summer 2008
- Women’s History Recognition for Professional & Academic Leadership
- Washington State University, Fall 2005
- Leadership Development Program-Class 14
- ESCOP/ACOP, Summer 2005
Plant virology, Insect vector biology, biotechnology for pathogen/vector control
Plant virology (DNA viruses), emergent insect-transmitted viruses/fastidious bacteria; functional genomics insect vector-pathogen interactions; molecular epidemiology; diagnostics; algal biology for biofuel production; international collaborative research and training
Directed ResearchPLS 592 (Fall 2021)
DissertationPLS 920 (Fall 2021)
ResearchPLS 900 (Fall 2021)
ResearchPLS 900 (Spring 2021)
DissertationPLS 920 (Fall 2020)
ResearchPLS 900 (Fall 2020)
DissertationPLS 920 (Spring 2020)
General VirologyPLS 333 (Spring 2020)
Independent StudyPLS 499 (Spring 2020)
ResearchPLS 900 (Spring 2020)
DissertationPLS 920 (Fall 2019)
Intro to ResearchPLS 695C (Fall 2019)
ResearchPLP 900 (Fall 2019)
ResearchPLS 900 (Fall 2019)
DissertationPLS 920 (Spring 2019)
ResearchPLP 900 (Spring 2019)
ResearchPLS 900 (Spring 2019)
Comparative VirologyACBS 611 (Fall 2018)
Comparative VirologyMIC 611 (Fall 2018)
Comparative VirologyPLP 611 (Fall 2018)
ResearchPLS 900 (Fall 2018)
DissertationPLS 920 (Spring 2018)
General VirologyPLS 333 (Spring 2018)
ResearchPLS 900 (Spring 2018)
DissertationPLS 920 (Fall 2017)
ResearchPLP 900 (Fall 2017)
ResearchPLS 900 (Fall 2017)
DissertationPLS 920 (Spring 2017)
Independent StudyPLS 499 (Spring 2017)
ResearchPLP 900 (Spring 2017)
ResearchPLS 900 (Spring 2017)
Curr Top Plant Sci-AdvPLS 595B (Fall 2016)
DissertationPLS 920 (Fall 2016)
Independent StudyPLS 499 (Fall 2016)
ResearchPLS 900 (Fall 2016)
ThesisPLS 910 (Fall 2016)
Independent StudyPLS 399 (Summer I 2016)
DissertationPLS 920 (Spring 2016)
General VirologyPLS 333 (Spring 2016)
ResearchPLS 900 (Spring 2016)
ThesisPLS 910 (Spring 2016)
- Brown, J. K. (2016). Vector-Plant Pathogen Interactions. St Paul, MN: APS Press.More infoBOOK EditorVector-Plant Pathogen Interactions. 2016. Ed. Brown, J.K. American Phytopathological Society Press, St Paul MN. 496pp
- 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.More infoBrown, 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.More infoCicero, 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.More infoLangham, 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. K., Waller, P. M., Gao, S., & Steichen, S. (2020). Association between algal productivity and phycosphere composition in an outdoor Chlorella sorokiniana reactor based on multiple longitudinal analyses.. Microbial biotechnology, 13(5), 15.
- 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
- 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:10.1111/1751-7915.13591More infoMicroalgae 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.
- 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
- 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
- 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: 10.4172/2324-8955.1000180More infoPeer-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-PDNMore infoPeer-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.0198953More infoDespite 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)More infoPeer-reviewed Short Report (Disease Note)
- 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
- 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.More infoVyas, 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].More infoXie, 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.
- 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
- 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.More infoLeke, 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.More infoLeke, 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.More infoAlabi, 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.More infoHadjistylli, 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.More infoCicero, 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/srep38469More infoMalik, 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.More infoMcRoberts, 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.More infoChen, 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..More infoChingandu, 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..More infoLeke, 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.More infoQuintela, 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.More infoUnkefer, 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.
- 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.More infoCicero, 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.
- 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.More infoLeke, 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.
- 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..More infoVyas 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.More infoZia-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.More infoSattar, 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.More infoSattar, 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.More infoCicero, 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.More infoBrown, 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. (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.More infoFisher, 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.More infoNaim, 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.More infoVarsani, 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.More infoN’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.More infoAl-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.More infoHameed, 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.More infoTang, 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.More infoIdris, 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.More infoHadjistylli, 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.More infoMusser, 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.More infoAl-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.More infoGao, 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.More infoVarsani, 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.More infoIdris, 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
- 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.More infoHadjistylli, 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).
- 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.More infoHosseinzadeh, 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.
- 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.More infoVarsani, 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., 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.More infoVarsani, 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. (2013). A genome-wide pairwise-identity-based proposalfor the classification of viruses in the genus, Mastrevirus (family, Geminiviridae).. Archives of Virology, 158:(1411-1424).More infoMuhire, B., D.P. Martin, J.K. Brown, J. Navas-Castillo, E. Moriones, F.M. Zerbini, R. Rivera-Bustamante,
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.More infoShe, 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.More infoUr-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..More infoLegg, 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..More infoHosseinzadeh, 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.More infoAngelova, 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.More infoA 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;#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;#160;% of the plants and the development of severe curling symptoms, whereas only 20&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;#160;% vs. 20&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.More infoAbstract: 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.More infoPMID: 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.
- 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.More infoAbstract: 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.More infoPMID: 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., 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., 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.More infoPMID: 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., 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.More infoPMID: 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-.
- 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.More infoDOI 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.More infoAbstract: 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.More infoAbstract: 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.More infoDOI: 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.More infoDOI: 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.More infoPMID: 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.
- 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.More infoPMID: 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., 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.More infoIdris, 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.More infoPMID: 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.
- 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).More infoPMID: 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., 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).More infoe34817. 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.More infodoi: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.More infoPMID: 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., 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.More infodoi: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.More infoAbstract: 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.More infoAbstract: 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-.
- 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.More infoPMID: 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., 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.More infoPMID: 21394606;
- 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.More info201x. ; 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.More info[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.More infoAbstract: 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., 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.More infoPMID: 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.
- 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.More infoPMID: 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.
- 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-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-.
- 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.More infoPMID: 20574644;Abstract: Rhynchosia minima (L.) DC. (Fabaceae) plants exhibiting bright golden mosaic symptoms were previously associated with begomovirus infection in Yucatan, México . 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.More infoAbstract: 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.
- 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.More infoAbstract: 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.More infoPMID: 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.
- 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-.
- 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.More infoAbstract: 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.More infoPMID: 19774336;PMCID: PMC2853933;
- 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.More infoPMID: 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.
- 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.More infoPMID: 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.
- 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-.
- 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.More infoPMID: 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.
- 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.More infoPMID: 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.
- 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.More infoPMID: 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.
- 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.More infoPMID: 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 . 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.More infoPMID: 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.
- 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.More infoPMID: 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.
- 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.More infoPMID: 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.
- 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.More infoAbstract: 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.More infoAbstract: 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(4), 199-206.More infoAbstract: 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.More infoPMID: 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.
- 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.More infoAbstract: 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.More infoPMID: 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). 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.More infoPMID: 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.
- 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.More infoAbstract: 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.More infoAbstract: 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.
- 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.More infoAbstract: 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(4), 233-240.More infoAbstract: 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.More infoAbstract: 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.More infoAbstract: 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.
- 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.More infoPMID: 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.
- 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.More infoAbstract: 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.More infoAbstract: 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.
- 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.More infoAbstract: 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.More infoAbstract: 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.More infoPMID: 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., 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.More infoPMID: 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.
- 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.More infoPMID: 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.
- 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.More infoPMID: 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., 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.More infoPMID: 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.
- 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.More infoPMID: 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.More infoPMID: 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.More infoAbstract: 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.More infoAbstract: 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.More infoPMID: 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.
- 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.More infoPMID: 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.
- 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.More infoAbstract: 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, EACMV-UG2 and EACMV-UG2). 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 produced the RFLP fragments predicted for the published sequences of EACMV-UG2/UG2Mld/UG2Svr. However, both EACMV-UG2 and EACMV-UG2, 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.More infoPMID: 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.
- 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.More infoPMID: 12557003;
- 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.More infoPMID: 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.
- 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.More infoPMID: 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.
- 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.More infoAbstract: 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, 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.More infoAbstract: 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.More infoPMID: 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, 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.More infoAbstract: 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).More infoMonopartite 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.More infoPMID: 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.
- 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.More infoPMID: 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.
- 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.More infoPMID: 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.
- 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.More infoAbstract: 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., 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.More infoPMID: 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.
- 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.More infoPMID: 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.
- 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.More infoPMID: 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.
- Brown, J. K. (2000). Molecular markers for the identification and global tracking of whitefly vector-Begomovirus complexes. Virus Research, 71(1-2), 233-260.More infoPMID: 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., 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.More infoPMID: 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., 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.More infoPMID: 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.
- 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.More infoPMID: 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.
- 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.More infoPMID: 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.
- 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.More infoAbstract: 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.More infoPMID: 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.
- 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.More infoPMID: 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.
- 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.More infoAbstract: 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.More infoAbstract: 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.
- 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.More infoPMID: 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.
- 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.More infoAbstract: 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.More infoAbstract: 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.
- 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.More infoAbstract: 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.More infoPMID: 8812594;
- 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.More infoAbstract: 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.More infoAbstract: 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.More infoAbstract: 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. (1995). Molecular analysis of cyclodiene resistance-associated mutations among populations of the sweetpotato whitefly Bemisia tabaci. Pesticide Biochemistry and Physiology, 51(3), 220-228.
- 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.More infoPMID: 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., 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.More infoAbstract: 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.More infoAbstract: 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.More infoAbstract: 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.More infoAbstract: 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.More infoAbstract: 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.
- 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.
- 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.More infoAbstract: 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.
- 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.More infoAbstract: 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.
- 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.More infoAbstract: 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
- 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.More infoAbstract: 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.
- 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. (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.More infoInvited 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.More infoInvited 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.More infoinvited 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.More infoInvited 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.
- 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.
- 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.
- 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.More infoInvited 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.
- Brown, J. K. (2018, March). Viruses of grapevines: Vectors and diseases. Viticulture Workshop, University of Arizona. Benson, AZ: Extension.
- 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.
- 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.More infoInvited 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.More infoInvited 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).More info2.5 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.More infoCelebration 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.More infoFunctional 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.More infoInvited 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.More infoRe-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.More infoInvited 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.More infoInvited 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.More infoSymposium: 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.More infoPlenary: 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.More infoEmergent 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.More infoInvited 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.More infoInvited 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.More infoInvited 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.More infoSymposium: 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.More infoComparative 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.More infoInvited 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.More infoSeminar: 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.
- 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.
- 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).More infoLammers, 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.More infoLeke, 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.
- 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#playMore infoWebinar 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/More infoWebCast- 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.
- Brown, J. K. (2018, February). Cacao Swollen Shoot Virus. Radio Interview, Bill Buckmaster Show.More infoRadio 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..More infoBrown, 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=14271More infoBrown, 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/