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 Entomology and 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 technique 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:
2005 Scientific Report: Nelson Laboratory

Selected publications:

Liu, J.-Z., Richerson, K. and Nelson, R. S. Growth conditions for plant virus-host studies. Curr. Protoc. Microbiol. (in press)

Harries, P. A., Palanichelvam, K., Yu, W., Schoelz, J. E. and Nelson, R. S. (2009) The Cauliflower mosaic virus protein P6 forms motile inclusions that traffic along actin microfilaments and stabilize microtubules. Plant Physiol. 149, 1005-1016 (First published on November 21, 2008; 10.1104/pp.108.131755)

Scofield, S. R. and Nelson, R. S. (2009) Resources for virus-induced gene silencing (VIGS) in the grasses. Plant Physiol. 149, 152-157

Harries, P. A., Palanichelvam, K., Bhat, S. and Nelson, R.S. (2008) Tobacco mosaic virus 126-kDa protein increases the susceptibility of Nicotiana tabacum to other viruses and its dosage affects virus-induced gene silencing. Mol. Plant-Microbe Interact. 21, 1539-1548

Melcher, U., Muthukumar, V., Wiley, G. B., Min, B. E., Palmer, M. W., Verchot-Lubicz, J., Nelson, R. S., Roe, B. A., Vaskar, T. and Pierce, M. L. (2008) Evidence for novel viruses by analysis of nucleic acids in virus-like particle fractions from Ambrosia psilostachya. J. Virol. Methods 152, 49-55

Quan, S., Nelson, R. S. and Deom, C. M. (2008) The methyltransferase domain of the 1a protein of cowpea chlorotic mottle virus controls local and systemic accumulation in cowpea. Arch. Virol. 153, 1505-1516

Harries, P.A. and Nelson, R.S. (2008) Movement of viruses in plants. In: "Encyclopedia of Virology" 3rd Edition. Mahy, B. and van Regenmortel, M. eds., Elsevier, vol. 3, pp. 348-355

Itaya, A., Zhong, X., Bundschuh, R., Qi, Y., Wang, Y., Takeda, R., Harris, A.R., Molina, C., Nelson, R.S. and Ding, B. (2007) A structured viroid RNA serves as a substrate for dicer-like cleavage to produce biologically active small RNAs but is resistant to RNA-induced silencing complex-mediated degradation. J. Virol. 81, 2980-2994

Ding, X.S., Schneider, W.L., Chaluvadi, S.R., Rouf Mian, M.A. and Nelson, R.S. (2006) Characterization of a Brome mosaic virus strain and its use as a vector for gene silencing in monocotyledonous hosts. Mol. Plant-Microbe Interact. 19, 1229-1239

Sasaki, N., Park, J.-W., Maule, A.J. and 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 349, 396-408

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

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