Evaluation of TYLCV-resistant Tomato Germplasm Using Molecular Markers

Tomato yellow leaf curl virus (TYLCV) infection causes serious economic losses in tomato production world-wide, and the development of new domestic cultivars with high levels of resistance to TYLCV is required. In this study, major advanced breeding lines carrying TYLCV-resistance loci, Ty-1, Ty-2, Ty-3, and Ty-3a were collected from overseas breeding programs, and their allelic composition of each resistance locus were confirmed by using public PCR-based DNA markers. Perfect matches between marker genotypes and the resistance indicated a feasibility of marker-assisted selection (MAS). In addition, genetic relationship of the TYLCV-resistant germplasm with commercial hybrids broadly grown in South Korea and other breeding lines were evaluated by AFLPs. A very close genetic background among these tomato germplasm revealed by the genetic similarity coefficient (0.87 to 1.00) and UPGMA implied the easiness of a rapid incorporation of the resistance genes. Phenetic tree showed a close relationship between TYLCV-resistant CLN lines and general type commercial hybrids, while Gc lines formed an independent group distinguished from both general and cherry type cultivars. Pyramiding TYLCV-resistance alleles using the resistant germplasm and DNA markers introduced in this report will greatly improve the breeding process for high levels of TYLCV-resistance. For accurate evaluation of the TYLCV-resistance, however, a reliable method of bio-assay still remains to be established.