Plant Defense and the Counter Defense by Viruses

Muzafar Ahmad Shiekh*

Abstract

RNA silencing is a sequence specific RNA degradation process triggered by the formation of double stranded RNA that can be introduced by a virus or transgene. RNA silencing was first discovered in transgenic plants, where it was termed co-suppression or post transcriptional gene silencing (PTGS). In plants, it serves as an antiviral defense, and many plant viruses encode suppressors of silencing. RNA silencing has been a robust host defense mechanism against plant viruses is generally countered by virus-encoded silencing suppressors. This strategy now increasingly recognizes to be used by most plant viruses. We are presenting here an overview of the common features shared by some of the best studied plant viral silencing suppressors followed of the characteristics of the few reported plant viral suppressors.