Tomato yellow leaf curl virus disease of tomato and its management through resistance breeding: a review

摘要

The whitefly (Bemisia tabaci Gennadius) transmitted Tomato yellow leaf curl virus (TYLCV) disease is a limiting factor in tomato production. Breeding resistance into tomatoes is one of the options to manage the disease. Among various screening techniques available for TYLCV, whitefly mediated individual plant inoculation technique is the most reliable one. Till date, six independently inherited major resistance genes and few Quantitative Trait Loci (QTLs) have been mapped in wild tomato species including S. chilense (Ty-1, Ty-3, Ty-4 and Ty-6), S. habrochaites syn. L. hirsutum (Ty-2), and S. peruvianum (ty-5). Ty-1 and Ty-2 genes express complete or nearly complete dominance, while Ty-3 shows partial dominance. These three genes have been extensively used in resistance breeding programs to combat both the monopartite and the bipartite begomoviruses. Since the Ty-genes in general exhibit partial or incomplete dominance, single gene F-1 hybrids are less effective than the pure lines homozygous for the resistance gene. Therefore, for hybrids to be effective either both the parents should be resistant or they involve multiple resistance genes. In this review, we have compiled up-to-date information on TYLCV occurrence and pathogen variability, allele mining, genetic mapping and cultivar development; and visualised future prospects of TYLCV resistance breeding in tomato.