Virus Resistant Transgenic Plants for Environmentally Safe Management of Viral Diseases

Abstract

Plant viruses are one of the major yield reducing factors for agricultural and horticultural crops. In India, most destructive diseases are caused by gemini-, poty-, and tospoviruses. Virus resistant transgenic plants (VRTPs), developed by the transfer of transgenes from virus, plant or other origins, have been found resistant to a wide range of viruses. The most successful approach is the viral coat protein mediated resistance (CPMR). Other transgenes of viral origin, which have shown promise are: replicase protein, movement protein, proteases, and antisense sequences. 'R'-genes from plants, plantibodies and yeast RNase genes are also useful for developing VRTPs. In a large number of VRTPs developed using transgenes of viral origin, resistance is conferred by post-transcriptional gene silencing

(PTGS); in some cases PTGS has been overcome when plants are infected by a heterologous virus, indicating need for cautious approach. Overall, the bio-safety concerns in the use of VRTPs get insignificant, but these must be addressed scientifically. In India, initiatives have been taken for developing VRTPs to manage important plant viral diseases. The present world area under VRTPs is about 0.4 mha. Judging from the success of various strategies, the

area under VRTPs is expected to grow at a fast rate in the coming years.