Chapter 28 - RNA interference against RNA viruses in plants

Abstract

Viruses are the biotrophic parasites of plants, cause a wide variety of symptoms, and are responsible for considerable yield loss in a variety of crops. The genera, viz., Tospovirus, Ilarvirus, Cucumovirus, and Potyvirus, are the major RNA plant viruses that infect cultivated crops worldwide which leads to huge loss. The virus disease management relies upon the use of prophylactic measures, cultural practices, planting resistant cultivars, vector control options, and molecular approaches. The efforts made through the conventional breeding program by developing resistant cultivars against viruses that are not successful in all crops due to unavailability of resistant sources. Alternatively, the RNA silencing technology has been explored as an advanced biotechnological tool for the control of virus diseases in crop plants. The antiviral mechanism through RNA silencing in plants is also known as RNA interference (RNAi) or posttranscriptional gene-silencing (PTGS). RNA silencing is a surveillance response induced by double-stranded RNA (dsRNA), wherein the dsRNA is cleaved into short small interfering RNA (siRNA), which is the key attribute for sequence-specific degradation of mRNA. The plants expressing sense and antisense gene fragments of viruses have shown resistance to virus. The inverted repeat constructs producing self-complementary RNAs (hairpin RNAs) from viral origin have efficiently induced virus resistance in transgenic plants through RNA-silencing mechanism. RNA silencing has expedited the molecular basis of plant antiviral systems, since it allows more accurate downregulation of gene expression without influencing the expression of other genes.