Chili Leaf Curl Disease in Asia: Diversity and resistance

Start date: 1 July 2020
End date: 30 June 2023

The primarily limitations to increased chili productivity and quality are biotic and abiotic stresses. The past three decades have seen the number of virus species infecting chili as well as virus disease incidence considerably increase. Likely, the most devastating chili-infecting viruses, especially in tropical and subtropical regions, are members of the whitefly- (Bemisia tabaci) transmitted Begomovirus (Geminiviridae), which cause chili leaf-curl disease (ChiLCD). In some of the hotspots for the disease, losses of 100% have been reported. Due to ChiLCD, farmers have switched from growing high value chili to low return cotton, maize, or other crops. Management of Begomoviruses has been based primarily on insecticides against the whitefly vector. However, the use of insecticides has been found to be only partially effective, costly for producers, and represents a hazard to farmers, consumers, and the environment, while limiting export potential through presence of pesticide residue. Furthermore, insecticides to manage the vector are often ineffective because they may only be applied once symptoms are seen, by which time transmission of the virus has already occurred.

An effective alternative to harmful insecticide applications for management of Begomovirus is the development of resistant cultivars. In order to effectively breed for resistance, an understanding of the epidemiology, genetic diversity, and phylogeny of the pathogen is required. Despite the severe losses due to begomoviruses, systematic studies of the species of Begomovirus in different chili-production regions in Asia are limited. In this project, we take a multimodal approach as the most efficient and impactful strategy to tackle Chili Leaf Curl Disease in Asia, with the overall objective of expanding the boundaries of our understanding of the genetics of resistance in the host and the phylogeny and genetic recombination rates in the pathogen. The specific objectives include 1) confirmation of WorldVeg resistance sources to new ChiLCD isolates, 2) identification of novel sources of resistance to ChiLCD in a biodiverse germplasm set, and 3) collection and phylogenetic characterization of the Begomovirus species infecting chili and other hosts across Asia.