Richard S. Nelson, Ph.D. Scientist e-mail: rsnelson@noble.org

Ph.D., Biology, University of Illinois Joined the Noble Foundation in 1988

Adjunct faculty appointment: Oklahoma State University, Dept. of Plant Pathology

Research emphasis: Molecular and cellular biology of virus movement in plants

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The overall objective of research within my laboratory is to understand how plant RNA viruses move and accumulate in their hosts. Specifically, we are studying the route by which viruses move from initially infected cells into cells within the vascular tissue for transport to other parts of the plant. We are also interested in the route viruses use to escape from the vascular tissue to initiate an infection in the upper uninoculated leaves and virus replication in this tissue. This research necessarily includes the study of gene silencing and silencing suppression in this tissue.

In order to identify the viral proteins or nucleic acid sequences necessary for viral passage from cell-to-cell and leaf-to-leaf and its subsequent accumulation we have assembled a battery of site-directed or truncated cDNA mutants of tobacco mosaic virus strains from which infectious transcripts can be produced. These mutants have differing movement and systemic accumulation phenotypes allowing us to identify the viral sequences necessary for these activities. Dr. X.S. Ding has initiated an independent project to study the cell-to-cell and leaf-to-leaf movement and subsequent accumulation of viruses infecting monocot plants.

It is apparent that virus movement and systemic accumulation requires the presence of various viral proteins interacting with specific host factors, and we are attempting to characterize these host factors. In addition, we are identifying the cell boundaries that limit infection.

We utilize molecular biological, immunocytochemical, in situ localization, microinjection and classical and confocal fluorescence microscopy techniques to answer the questions we pose.

By identifying viral and host factors important for virus movement and accumulation, the function of these nucleic acids and proteins, and the location of their effect, we can begin to design rational strategies to make plants resistant to vascularly-derived viral infection. Such a novel resistance strategy could be combined with other proven strategies for obtaining transgenic plants resistant to viral challenge, thereby creating a potentially impenetrable barrier to viral infection and spread due to multiple mechanisms of protection. In addition, we are utilizing our knowledge in this area to study the function of host genes in monocotyledonous and dicotyledonous plants through virus-induced gene silencing.

See Also:
2001-2002 Scientific Report: Nelson Laboratory (pdf)

Selected publications:
Ding, X.S., Rao, C. S. and Nelson, R.S. Analysis of gene function through virus-induced gene silencing. In "Methods in Molecular Biology" series on "Plant-Pathogen Interactions: Methods and Protocols". Ronald, P. ed., Humana Press, In press

Sasaki, N., Park, J.-W., Maule, A. J., Nelson, R.S. (2006) The cysteine-histidine-rich region of the movement protein of Cucumber mosaic virus contributes to plasmodesmal targeting, zinc binding and pathogenesis. Virology, In press

Wren, J.D., Roossinck, M.J., Nelson, R.S., Scheets, K. M., Palmer, M. W., Melcher, U. (2006) Plant virus diversity and ecology. PLoS Biology 4, 314-315

Ju, J.-H., Samuels, T. D., Wang, Y.-S., Blancaflor E., Payton, M., Mitra R., Krishnamurthy, K., Nelson, R.S., Verchot-Lubicz, J. (2005) The Potato virus X TGBp2 movement protein associates with endoplasmic reticulum-derived vesicles during virus infection. Plant Physiol. 138, 1877-1895

Nelson, R.S. and Citovsky V. (2005) Plant Viruses. Invaders of cells and pirates of cellular pathways. Plant Physiol. 138, 1809-1814

Mian, M.A.R., Zwonitzer, J.C., Hopkins, A. A., Ding, X.S., and Nelson, R.S. (2005) Response of tall fescue genotypes to a new strain of Brome mosaic virus. Plant Dis. 89, 224-227

Nelson, R.S. (2005) Movement of viruses to and through plasmodesmata. In: "Plasmodesmata". Oparka, K., ed., Blackwell Publishing, pp. 188-211

Liu, Jian-Zhong, Blancaflor, E.B., and Nelson, R.S. (2005) The Tobacco mosaic virus 126-kilodalton protein, a constituent of the virus replication complex, alone or within the complex aligns with and traffics along microfilaments. Plant Physiol. 138, 1853-1865

Ding, X.S. and Nelson, R.S. (2004) Sources of virus inoculum under natural conditions. In: "Viruses and Virus diseases of Poaceae (Gramineae)". Lapierre, H., and Signoret, P.-A., eds., INRA editions, Versailles, France, pp. 109-111

Yang, S.-J., Carter, S.A., Cole, A.B., Cheng, N.-H., and Nelson, R.S. (2004) A natural variant of a host RNA-dependent RNA polymerase is associated with increased susceptibility to viruses by Nicotiana benthamiana. Proceedings of the National Academy of Sciences, 101, 6297-6302

Cheng, N.-H., Liu, J.-Z., Nelson, R.S., and Hirschi, K. D. (2004) Characterization of CXIP4, a novel Arabidopsis protein that activates the H⁺/Ca²⁺ antiporter, CAX1. FEBS Letters, 559, 99-106

Li, Y., Bao, Y. M., Wei, C. H., Kang, Z.S., Zhong, Y.W., Mao, P., Wu, G., Chen, Z.L., Schiemann, J., and Nelson, R.S. (2004) Rice dwarf phytoreovirus segment S6-encoded nonstructural protein has a cell-to-cell movement function. Journal of Virology, 78, 5382-5389

Ding, X.S., Liu, J., Cheng, N.-H., Folimonov, A., Hou, Y.-M., Bao, Y., Katagi, C., Carter, S.A., and Nelson, R.S. (2004) The Tobacco mosaic virus 126kDa protein associated with virus replication and movement suppresses RNA silencing. Molecular Plant-Microbe Interactions, 17, 583-592