Applications of Virus Induced Gene Silencing (VIGS) in Plant Functional Genomics Studies

Virus induced gene silencing (VIGS) is an effective technology that exploits an antiviral defense mechanism in plants. It is a recently developed gene transcript suppression technique for characterizing the function of plant genes. VIGS is rapid, efficient and specific system for transient gene silencing. The major steps in VIGS includes; engineering viral genomes to the appropriate viral vector to incorporate fragments of host genes that are targeted to be silenced, infecting the appropriate plant hosts and silencing the target genes as part of the defense mechanism of the plant against virus infection. The VIGS vector is a recombinant virus engineered to be able to carry a piece an endogenous gene from the host. During infection with the modified vector, the host’s defense reaction will be induced against the cloned host gene; a loss of function phenotype makes it possible to identify the function of the gene. The recombinant virus is introduced into plant cells through Agrobacterium tumefaciens mediated transient expression or in vitro transcribed RNA inoculation or direct DNA inoculation. The Trans gene is amplified along with the viral RNA by RNA dependent RNA polymerase generating dsRNA molecules. dsRNA is the triggering molecule of Post transcriptional gene silencing. VIGS as a reverse genetics tool for functional genomics studies presenting several advantages. Despite its great potential, many limitations remain to be overcome. In this review, the molecular mechanism in VIGS technology, its advanced application in plant functional genomics studies and the major limitation and potential future prospects were briefly discussed.