Cloning of Gene Silencing Regulator (RGS-CAM) into the Viral Vector.

Post-transcriptional gene silencing (PTGS) is a fundamental regulatory mechanism operation in plants, animals and fungi. PTGS serves as an antiviral defense mechanism in plants and may play a similar role in other organisms. The Vance lab has identified a plant virus protein, the helper component-proteinase (HC-Pro) of potyviruses that suppresses PTGS and thereby acts as a counter-defense. Preliminary results from this lab have also identified a cellular protein that interacts with HC-pro in the yeast two-hybrid system. This cellular protein is a novel calmodulin-related protein (termed rgs-CaM) which, like HC-Pro itself, suppresses PTGS. Our current hypothesis is that HC-Pro suppression of PTGS is mediated via activation of rgs-CaM. The goal of this project was to eliminate rgs-CaM expression using a virus induced gene silencing (VIGS) approach and then determine if HC-Pro could still suppress PTGS in the rgs-CaM negative plants. The investigation of suppressors of PTGS is useful in a practical sense. These proteins have significant potential to improve yield in technologies that use plants to express foreign gene products. Given the antiviral nature of gene silencing in plants and the indications that PTGS is an ancient mechanism in eukaryotic organisms, the work could lead to development of antiviral strategies in both plants and animals.

Daria S. Solovieva
South Carolina Governor's School for Science and Mathematics