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Steven A. Lommel
Professor of Plant PathologyProfessor of GeneticsAssistant Director, North Carolina Agriculture Research Service
Editorial Boards
Research InterestsThe research program in my laboratory has focused on a small RNA plant virus, red clover necrotic mosaic virus (RCNMV) as a model system to study the molecular mechanisms of plant viral pathogenesis (click here to see a model of the virion structure or a representation of the RCNMV genome). Over the past decade the laboratory has focused on using RCNMV to study the molecular mechanisms of virus movement and systemic infection. We genetically established that the virus-encoded movement protein (MP) is necessary for local movement of the virus infection and that the MP and capsid protein (CP) are essential for long-distance transport. A saturation mutagenesis study indicated that the MP has a number of functional domains, including those for binding to single-stranded RNA, targeting to plasmodesmata, modification of plasmodesmata, trafficking RNA from cell to cell, and effecting long-distance transport. In collaboration with Dr. Bill Lucas, UC Davis, we showed that a viral RNA-MP complex is formed and is transported through the plasmodesmata. Recently we have generated compelling genetic evidence that the MP and capsid protein must interact in order to facilitate long-distance transport. We are currently determining whether the virus needs to be in the form of a virion to facilitate long-distance transport. In parallel with the viral studies, a postdoctoral researcher in the laboratory has been developing a genetic screen in Arabidopsis and in Nicotiana benthamiana to identify host factors necessary for facilitating cell-to-cell and systemic infection of the virus. Again, the goal of this work is to understand the process of viral systemic infection in sufficient detail to design control strategies that prevent the establishment and spread of a virus infection. A couple of years ago, while developing new RCNMV gene expression constructs, we uncovered an unexpected and novel gene regulation mechanism based on an RNA-RNA interaction. This initial observation has led to a new line of investigation in the laboratory that is distinct from the movement program. We identified a novel bipartite RNA regulator of subgenomic RNA synthesis in RCNMV. We hypothesize that this regulator acts to sterically inhibit the procession of RNA polymerase on the viral template. This results in a premature termination event, generating a minus strand template for subgenomic RNA (sgRNA) synthesis. This regulator is composed of a trans-acting 34-nucleotide stem-loop (TA) encoded on the viral RNA-2, and an 8 nucleotide (nt) complementary sequence on the viral RNA-1 (click here for model of RNA elements involved in trans-activation). We believe this is the first report of RNA-mediated transcriptional regulation in an RNA virus (see abstract of Science paper). Based on our current data, we have a working model for the mechanism of sgRNA synthesis in RCNMV that is now being tested by molecular, genetic, and physical experimentation. Our laboratory has shown that RNA transcription can be regulated exclusively by the direct molecular interaction of another RNA molecule. This discovery not only establishes an entirely new mechanism for regulating transcription but also provides supporting evidence for the popular hypothesis that RNAs were the first molecules capable of independent replication and enzymatic activity in the "primordial soup of life." In addition to the mechanistic programs described, the laboratory nearly always has a project or two studying the etiology or epidemiology of a relevant virus disease. In the past we have worked on viral problems in the cut flower industry in Central and South America; the papaya industry in Hawaii; hard red winter wheat, corn and sorghum in the high plains of the United States; and most recently with the peppermint industry in the Northwest United States and the pepper industry in North Carolina. Current Laboratory Personnel
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Postdoctoral Associates
Links of Interest
Contact InformationDr. Steven A. Lommel Tel: (919) 515-6990 |
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NCSU Department of Plant Pathology | 3419 Gardner Hall, Raleigh, NC 27695-7616
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