Milestones in the development and applications of plant virus vector as gene silencing platforms

One of the main post-genomics challenges facing scientists remains the identification of gene function in a large number of plant species. Plant viruses offer great potential in linking genes to phenotypes through epigenetic expression or knockdown of selected genes. The past decade has seen the development and ever increasing applications of a gene knockdown technique termed virus-induced gene silencing (VIGS). VIGS recapitulates an RNA-mediated antiviral defense mechanism, mediating a homology-based post-transcriptional degradation of selected plant RNAs, leading to a loss-of-function phenotype. Due to its rapidity and increasing number of virus vectors developed as gene silencing platforms, VIGS has become a powerful technology to determine the function of genes in an increasing number of crop species, where the routinely available transgenesis or mutagenesis approaches are often not amenable to large genomes and complex genetic backgrounds.