Double stranded RNA expression and its topical application for non-transgenic resistance to plant viruses

Abstract

The discovery of RNA silencing has heralded a new phase in the understanding of nucleic acid metabolism and has provided researchers with alternative methods to define the biochemical, developmental and self-protection pathways in plants. Manipulation of these pathways to ultimately modify, induce or enhance favorable traits and repress or completely eliminate unfavorable qualities including disease susceptibility can be achieved by insertion or infiltration of transgenes encoding appropriate effectors. Remarkably, in contrast to transgene derived viral resistance, the RNA silencing mechanism can be readily induced by the topical application of dsRNA effector molecules. The current review summarises the various dsRNA production systems available for producing the large amounts of dsRNA required for topical application onto field grown crops. Also discussed are several investigations utilising a topical application of exogenous, sequence-specific dsRNA to induce the RNA silencing mechanism for viral resistance in plants. Currently, there are limitations for the spray-on application of dsRNA for field use. Further research to define a new phase in the non-transgenic delivery of RNA silencing for complete management of plant pathogens is crucial for its commercial application.