RNA interference is a gene regulatory mechanism that limits the level of transcript in two ways: suppressing transcription (transcriptional gene silencing) and degrading mRNA (post-transcriptional gene silencing) . It is a process that occurs in all eukaryotic cells as an approach to cellular defense and acts as an antiviral mechanism in higher plants and insects. RNA interference is triggered by double-stranded RNA that uses the genes own DNA sequence to turn it off, a process known as gene silencing. The mechanism of RNA interference involves the following steps:

• Long double-stranded RNA is diced into small fragments with the help of an enzyme called Dicer. These small fragments are known as siRNA or small interfering RNA.
• The siRNAs are passed through the RNA-induced silencing complex. The duplex unwinds, and the RNA is activated. Such complexes promote RNA degradation and inhibit translation.
• The siRNA binds to Argonaute protein, and one of the strands from the double-stranded is removed. The remaining strand binds to the mRNA target sequences. The Argonaute protein either cleaves the mRNA or recruits other factors to regulate the target sequence.

RNA interference has several applications, including gene knockdown, functional genomics, and studying the functions of genes in cell culture and in model organisms. It is also used for gene mapping and annotation in plants.