302 Life Sciences Bldg.
Baton Rouge, LA 70803
Phone: (225) 578-1384
Fax: (225) 578-1415
University of Arkansas, Ph.D., 1984
University of Arkansas, M.S., 1981
University of Costa Rica, B.S. (Ing. Agr.), 1978
As a plant pathologist with the Louisiana State University Agricultural Center, my main job responsibility is the development of a research program addressing diseases caused by viruses in Louisiana crops. Other duties include teaching a graduate course and a laboratory on plant virology, directing graduate student research, and working with extension personnel on the diagnosis of viral diseases.
Based on the type of relationship with the host, plant viruses can be grouped as acute or persistent. Most acute viruses cause disease and have been well studied. Due to the apparent lack of effect on the host phenotype, limited information is available on persistent plant viruses. Persistent plant viruses are dsRNA virus members of the families Endornaviridae, Chrysoviridae, Partitiviridae, and Totiviridae. They have been reported to infect several economically important crops, such as avocado, alfalfa, barley, beets, cherry, common bean, fava bean, melon, pepper, rice, and tomato, among others. My laboratory and collaborators have identified persistent virus-free and persistent virus-infected lines of cultivars of bell pepper, common bean, and jalapeño pepper. Preliminary comparative experiments using these lines suggest that in some cases, these viruses may have an effect on the phenotype, seed/fruit yield, seed emergence, and the host reaction to some acute plant viruses. It is possible that the persistent viruses are in a symbiotic (mutualistic) relationship with the host and provide an unknown benefit.
Virus identification is important for developing control strategies, and another area of my research program focuses on plant virus identification and characterization and the development of detection tools. Graduate students in my laboratory and collaborators have identified, characterized, and developed detection tools for several newly recognized virus species causing diseases on sweet potato, pepper, tomatoes, citrus, common bean, and ornamental crops.
Valverde, R. A. and Clark, C. A. 2013. Begomoviruses. Pages 86-88 in:Compendium of sweetpotato diseases, pests, and disorders 2nd ed. C. A. Clark, D. M. Ferrin, T. P. Smith, and G. J. Holmes, eds. The American Phytopathological Society Press. St. Paul, MN.
Rao, G. P., Valverde, R. A., and Dovas, C. I. 2008. Techniques in Diagnosis of Plant Viruses Studium Press LLC, Houston, 302pp.
Valverde, R. A., Clark, C. A., Kokkinos, C. D., and Gutierrez, D. L. 2008. Sweet potato viral diseases. Pages: 251-272 in Characterization, diagnosis and management of plant viruses. Volume 1: Industrial crops. G. P. Rao, S. M. Khurana, and L. Lenardon eds. Studium Press, USA.
Valverde, R. A., and Fulton, J. P. 1996. Comoviruses: Identification and Diseases Caused. Pages 17-33 in: The Plant Viruses: Polyhedral Virions and Bipartite RNA Genomes. Harrison, B. D. ed. Plenum Publishing. New York, N. Y.
Dodds, J. A., Valverde, R. A., and Matthews, D. M. 1988. Detection and interpretation of dsRNAs. Pages 309-326 in: Viruses of Fungi and Simple Eukaryotes. Koltin, Y. and Leibowitz, M. J. eds. Marcel Dekker, Inc. New York, N. Y.
Articles in refereed journals
Okada, R., Young, C. K., Valverde, R. A., Sabanadzovic, S., Aoki, N., Hotate, S., Kiyota, E., Moriyama,H., & Fukuhara, T. 2013. Molecular characterization of two evolutionally distinct endornaviruses co-infecting common bean (Phaseolus vulgaris). Journal of General Virology 93:220-229.
Villanueva, F., Sabanadzovic, S., Valverde, R. A., and Navas-Castillo, J. 2012. Complete genome sequence of a double-stranded RNA virus from avocado. Journal of Virology 86:1282-1283.
Valverde, R. A. Sabanadzovic, S., and Hammond, J. 2012. Viruses that enhance the aesthetics of some ornamental Plants: beauty or beast? Plant Disease 96:600-611.
Roossinck, M. J., Sabanadzovic, S., Okada, R., & Valverde, R. A. 2011. The remarkable evolutionary history of endornaviruses. Journal of General Virology 92:2674-2678.
Lai, Y., Yi, G., Chen, C., Bhardwaj, K., Tragesser, B. J., Valverde, R. A., Zlotnick, A., Mukhopadhyay, S., Ranjith-Kumar, C. T., and Kao, C. C. 2011. Viral Double-strand RNA-binding Proteins Can Enhance Innate Immune Signaling by Toll-Like Receptor 3. PLoS ONE 6 (10): e25837. doi:10.1371/journal.pone.0025837
Okada, R., Kiyota, E., Sabanadzovic, S., Moriyama,H., Fukuhara, T., Saha, P., Roossinck. M. J., Severin, A., and Valverde, R. A. 2011. Bell pepper endornavirus: molecular and biological properties and occurrence in the genus Capsicum. Journal of General Virology 92:2664-2673.
Sabanadzovic, S. and Valverde, R. A. 2011. Properties of two cryptoviruses from pepper (Capsicum annuum). Virus Genes 43:307-312.
Valverde, R. A., Sabanadzovic, S., and Rush, M. C. 2011. Identification of Oryza sativa endornavirus in rice genotypes from breeding programmes in the United States. Plant Breeding 130:271-274.
Lozano, G., Trenado, H. Valverde, R. A. & Navas-Castillo, J. 2009. New begomovirus species of recombinant nature in sweet potato (Ipomoea batatas) and I. indica: taxonomic and phylogenetic implications. Journal of General Virology 90:2550-2562.
Valverde, R. A., Clark, C. A., and Valkonen, J. P. T. 2007.Viruses and virus disease complexes of sweetpotato. Plant Viruses 1:116-126.
Valverde, R. A. and Gutierrez, D. L. 2007. Transmission of a dsRNA in bell pepper and evidence that it consists of the genome of an endornavirus. Virus Genes 35:399-403.
Lotrakul, P.,and Valverde, R. A. 1999. Cloning of a DNA-A-like genomic component of sweetpotato leaf curl virus: nucleotide sequence and phylogenetic relationships. Molecular Plant Pathology On-Line. Mppol/1999/0206LOTRAKUL.
Arancibia, R. A., and Valverde, R. A. 1995. A cryptic virus from pepper. Plant Pathology 44:164-168.
Kousik, C. S., Snow, J. P., and Valverde, R. A. 1994. Comparison of double-stranded RNA components and virulence among isolates of Rhizoctonia solani AG-1 IA and AG-1 IB. Phytopathology 84:44-49.
Valverde, R. A., Nameth, S. T., Abdallha, A. O., Desjardins, P. R., and Dodds, J. A. 1990. Indigenous double-stranded RNA from pepper (Capsicum annuum). Plant Science 67:195-201.
Valverde, R. A., Nameth, S. T., and Jordan, R. L. 1990. Analysis of double-stranded RNA for plant virus diagnosis. Plant Disease 74:255-258.
Valverde, R. A., and Dodds, J. A. 1987. Some properties of isometric virus particles which encapsidate the satellite RNA of tobacco mosaic virus. Journal of General Virology 68:965-972.
Valverde, R. A., and Dodds, J. A. 1986. Evidence for a satellite RNA associated naturally with the U5 strain and experimentally with the U1 strain of tobacco mosaic virus. Journal of General Virology 67:1875-1884.
Valverde, R. A., Dodds, J. A., and Heick, J. A. 1986. Double stranded RNAs from plants infected with viruses having elongated particles and undivided genomes. Phytopathology 76:459-465.