RNA Interference: A Versatile Tool for Functional Genomics and Unraveling the Genes Required for Viral Disease Resistance in Plants

Virus-induced gene silencing (VIGS) is a powerful reverse genetics technology used to unravel the functions of genes. It uses viruses as vectors to carry targeted plant genes. The virus vector is used to induce RNA-mediated silencing of a gene or genes in the host plant. The process of silencing is triggered by dsRNA molecules, the mechanism is explained in this chapter. Over the years a large number of viruses have been modified for use as VIGS vectors and a list of these vectors is also included. As the name suggests, virus-induced gene silencing uses the host plant’s natural defense mechanisms against viral infection to silence plant genes. VIGS is methodologically simple and is widely used to determine gene functions, including disease resistance, abiotic stress, biosynthesis of secondary metabolites and signal transduction pathways. Here, we made an attempt to describe the basic underlying molecular mechanism of VIGS, the methodology and various experimental requirements, as well as its advantages and disadvantages. Finally, we discuss the future prospects of VIGS in relation to CRISPR/Cas9 technology. Besides using it to overexpress or silence genes, VIGS has emerged as the preferred delivery system for the cutting edge CRISPR/Cas9 genome editing technology.