What is RNAi Technique?

RNAi is a biological process in which a double stranded RNA is introduced to inhibit gene expression. RNAi technique can be used in all eukaryotic organisms. The method involves the silencing of a specific mRNA with a complementary dsRNA molecule. 

Procedure:

The dsRNA is introduced to the cell, which is first recognized by an enzyme DICER (an enzyme of the RNAase III family of nucleases); cuts dsRNA into small dsRNA molecules termed as SiRNA (Small Interferring RNA).

SiRNA is then incorporated into a large multi-subunit nuclease complex, “RISC” (RNA Induced Silecing Complex).

RISC unwinds SiRNA in an ATP-dependent step and finds homologous target mRNA (which is produced in the nucleus and reaches the cytoplasm for translation) using SiRNA swquence as a guide and cleaves these mRNA. 

In agriculture, RNAi technique is being used to control parasites on differnt plants. For example, a nematode Meloidegyne incognita infects the roots of tobacco plants and causes great reduction in yield.