Research Abstract:
Our research is directed toward elucidating mechanisms of plant virus replication and disease and developing resistance strategies in transgenic plants. Tobacco Mosaic Virus (TMV) is used as the model for most studies. Transgenic plants that produce TMV coat protein restrict disassembly of TMV, thereby limiting virus infection, per se; this is referred to as CP-mediated resistance. When mutations were introduced to the CP to decrease subunit interaction, the efficacy of CP-mediated resistance was reduced—while resistance was increased by mutations that strengthened such interactions. Certain mutations in the CP affected virus replication, and production of the 30 kDa movement protein of TMV. This resulted in restriction of cell-cell and long-distance spread of infection.
The TMV 30kDa Movement Protein (MP) is an integral membrane protein that is essential for cell-cell spread, but non-essential for replication per se. Using fluorescence microscopy in fixed and live cells and biochemical fractionation, the intracellular distribution of MP:GFP (green fluorescent protein) fusions were co-localized with sites of virus replication. Our current studies are designed to determine how the ER and cytoskeleton contribute to intra- and intercellular spread of virus infection and these studies are complemented with a genetic approach using Arabidopsis thaliana to identify host genes involved in cell-cell spread of infection.
Our studies of rice tungro bacilliform paravetrovirus (RTBV) include characterizing the role of transcription factors RF2a and RF2b, their binding to a cis DNA sequence element to regulate transcription of the RTBV promoter, and developing strategies to control virus infection in transgenic plants.
Selected Publications:
Hossain T, Rosenberg I, Selhub J, et al. Enhancement of folates in plants through metabolic engineering. Proc Natl Acad Sci USA 2004. Forthcoming.
Asurmendi S, Berg H, Koo JC, Beachy RN. Coat protein regulates formation of replication complexes during tobacco mosaic virus infection. Proc Natl Acad Sci USA 2004 101:1415-1420.
Dai S, Zhang Z, Chen S, Beachy RN. RF2b, a rice bZIP transcription activator, interacts with RF2a and is involved in symptom development of rice tungro disease. Proc Natl Acad Sci USA 2004 101:687-692.
Kawakami S, Watanabe Y, Beachy RN. Tobacco mosaic virus infection spreads cell to cell via replication complexes. Proc Natl Acad Sci USA 2004 101:6291-6296.
Koo JC, Asurmendi S, Bick J, Woodford-Thomas T, Beachy RN. Ecdysone agonist-inducible expression of a coat protein gene from tobacco mosaic Virus confers viral resistance in transgenic Arabidopsis. Plant J 2004 37:439-448.
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