Small interfering RNA-mediated regulation of gene expression and its role as a plant reverse genetic tool

In the era of genome sequencing, various techniques have been conceptualized for identifying the functions of annotated genes in model as well as crop systems. One of them is the use of small RNAs in the characterization of gene function. Small RNAs regulate gene expression in eukaryotic organisms in a post-transcriptional manner. Small interfering RNAs (siRNAs) are a group of short, double-stranded RNA (dsRNA) molecules that bind to and inhibit the translation of specific and complimentary mRNAs, thereby knocking-down target gene expression. The siRNA-mediated gene regulation that has initially evolved as a part of innate immunity in plants against invading pathogens also has assumed significance in plant development and has become one of the important tools in regulating mRNA abundance in cells in a post-transcriptional manner. The process of silencing of genes begins with the folding of complimentary RNAs and the production of small dsRNAs by the activity of type III ribonucleases. These small RNAs carry sequence-specific effectors of RNA silencing pathways that negatively regulate expression of genes, viruses, repetitive DNA sequences and transposons. In the current review, we briefly describe the siRNA-mediated regulation of gene expression and its merits and limitations as a reverse genetic tool for functional genomic studies in plants. © 2017, Indian Society for Plant Physiology.