Genetic Diversity on Resistance to Tomato Yellow Leaf Curl Virus in Tomato

Tomato yellow leaf curl disease (TYLCD) is a major constraint in tomato (Solanum lycopersicum) production worldwide since 1980’s. It is a viral disease caused by a cluster of virus species. Besides Tomato yellow leaf curl virus (TYLCV), the most invasive and best studied species, species of TYLCV-like viruses and strains have been identified and classified according to the description in the International Committee on Taxonomy of Viruses (ICTV). Controlling TYLCD is usually focused on reducing or avoiding the whitefly vector population by common practices of heavy spray of insecticides and/or the use of nets. Breeding TYLCV-resistant tomato cultivars is an economically and environmentally sustainable alternative. In the past, many wild tomato relatives have been screened for resistance to TYLCV. However, accession numbers were not always published and resistant sources were usually clarified only at species level, which led to redundant screenings for TYLCV resistance in different labs. This presentation will (1) summarize results of different screenings worldwide to illustrate genetic diversity on tomato resistance to TYLCV; (2) report on the progress and status of the identification and mapping of tomato genes (including Ty-1 to ty-6) and their allelic variants; and (3) discuss the challenges of TYLCV introgression breeding (e.g. chromosomal rearrangements) and possibilities for durable and broad-spectrum geminivirus resistance.