Managing chili leaf curl disease through RNAi based strategies

Chili leaf curl disease (ChiLCD) is one of the most devastating plant diseases in the world. As a result of its continuing rapid spread, leaf curl epidemics are developing in all agro climatic regions of India. The high altitude areas are less epidemic than warm coastal dry inland areas and the disease spread is particularly rapid in south India (Andhra Pradesh).The disease is caused by viruses belonging to genera Begomoviruses, family Geminiviridae (geminiviruses), mainly include Chili leaf curl virus (ChiLCV) though other begomoviruses may be included. The viruses are transmitted by an insect vector, mainly the whitefly, Bemisia tabaci. The genome of ChiLCV generally consists of a single circular single-stranded DNA-A molecule (ss DNA). It encodes six open reading frames, two (AV1 and AV2) in the Viral sense strand and four (AC1, AC2, AC3 and AC4) in the Complementary strand. Various (physical, mechanical and chemical) methods of control, aimed primarily at the vector of the virus are being practiced. In this article we focus on control by crop management, Host plant resistance to the virus and molecular strategies for virus resistance. Breeding for resistance appears to be the best approach for controlling this disease, although only partially resistant varieties are commercially available. We also provide an overview of the most outstanding achievements in ChiLCV research that may lead to more effective control strategies.