Rna interference: present status and future prospects in ameliorating the crop yield

The discovery of RNA interference (RNAi) in mid ninety’s added a new dimension in the regulation of gene expression by different types of RNA. It is a phenomenon in which double stranded RNA (dsRNA) is the initiating factor in post-transcriptional gene silencing. It is a process in which the introduction of a double stranded RNA (dsRNA) in the cells causes the specific degradation of an mRNA containing the same sequence. The double stranded RNA (dsRNA) and short interfering RNA (siRNAs) alone cannot degrade mRNA, but require the assistance of two enzymes namely Dicer and RNA induced silencing complex (RISC). Dicer was first discovered in Drosophila. It is a complex enzyme belonging to the RNase III family and has four different domains. RISC is the component of the RNAi machinery that uses siRNAs to track down and degrade the complementary mRNAs. It is diverse in its occurrence and applications. The double stranded RNA (dsRNA) has a direct role in inhibiting viral infection. It is potentially useful method to develop highly specific double stranded RNA (dsRNA) based gene silencing therapeutics (Shuey et al., 2002). This technology has practical applications in crop improvements such as in the production of potato virus Y (PVY) resistant potatoes (Smith et al., 2000). Modification of plant height via RNAi suppression of one of the gibberellin (GA) 20-oxidase (GA20ox) gene viz. OSGA20 Ox2 gene, in rice has been made possible (Feng et al., 2007). The field of RNA interference (RNAi) is moving at an impressive pace and generating exciting results. A better understanding of post-transcriptional gene silencing (PTGS) should allow a more efficient response to viral infection and the development of transgene/host associations that can override silencing to allow the expression of interested proteins.