Gene-Based Markers for the Tomato Yellow Leaf Curl Virus Resistance Gene Ty-3

The viral disease induced by Tomato yellow leaf curl virus (TYLCV) reduces tomato (Solanum lycopersicum) yield significantly in tropical and subtropical regions. A number of loci, including Ty-1 to Ty-5, conferring resistance to TYLCV have been described and introgressed into modern tomato cultivars. The availability of molecular markers linked to these genes would expedite the introgression of TYLCV resistance into commercial cultivars. In the present study, we developed gene-based markers linked to the Ty-3 gene using a segregating population derived from a cross between the TYLCV-resistant line S. lycopersicum ‘A45’ and the susceptible line S. lycopersicum ‘A39’. Agrobacterium-mediated screening was used to test TYLCV resistance of plants in the segregating population, and the resistance was evaluated by a visual scoring method and polymerase chain reaction analysis. By comparing sequences of the Ty-3 genes of the resistant and susceptible lines, two high-resolution melting (HRM) markers (Ty3-HRM1 and Ty3-HRM2) and one sequence characterized amplified region (SCAR) marker (Ty3-SCAR1) were developed. The HRM markers were based on single nucleotide polymorphisms at the 13th exon and the 15th intron, whereas the SCAR marker was based on a 246-bp deletion in the 16th intron. These gene-based markers will be useful tools for marker-assisted selection in breeding programs to improve TYLCV resistance of tomato.