CONCEPTS OF RNA INTERFERENCE AND ITS USES AS A PEST MANAGEMENT IN PLANTS AND BIOTECHNOLOGY: REVIEW
Fekede Girma
Abstract
RNAi is an RNA-dependent gene silencing process that is controlled by the RNA induced silencing complex (RISC). The process is initiated by short double-stranded RNA molecules in the cell’s cytoplasm, where they interact with the catalytic RISC component argonaute. The RNA is cleaved into short fragments by the enzyme dicer. Dicer binds and cleaves double-stranded RNAs to produce double stranded fragments of 20-25 positive base pairs, along with a few unpaired overhang bases on each end. There is an intrinsic mechanism probably present in all multicellular eukaryotes, which converts double stranded (ds) RNA into small (21 nt) RNAs (by cleavage with endo nucleases called Dicers) and uses them to direct sequence-specific degradation of cognate single-stranded RNAs. These small RNAs are termed short interfering (si) RNAs and the process is called RNA interference (RNAi). Curiously, most animals possess only one Dicer gene, whereas in plants Arabidopsis has four and poplar and rice seem to have five and six, respectively. RNAi as its application, it is importantly used for pest and disease management in plants without any negeative impact on the environment and with no intensive labor on human being.