Evaluation of phenotyping and genotyping for resistance against Tomato yellow leaf curl Thailand virus (TYLCTHV) validated by Ty-2, Ty-3, and Ty-4 genes in tomato

Tomato yellow leaf curl virus (TYLCV) caused by whitefly-transmitted begomoviruses is one of the most destructive and causing heavy losses in tomato yields, especially in sub-tropic and tropic regions including Thailand. Therefore, breeding a tomato cultivar resistant to TYLCV is necessary. The purpose of this research was to evaluate tomato cultivars which are resistant to TYLCV for Thailand's strain (TYLC-THV) with agronomic traits. The 35 tomato accessions obtained from The World Vegetable Center (AVRDC) were compared with the susceptible cultivar (Seedatip: KKU-T12002). The results of field evaluation showed that the 11 tomato accessions performed moderately resistant to TYLC-THV and their good agronomic traits. The results for resistance were classified into 3 groups based on their responses to TYLC-THV. The first group, i.e., KKU-T24003 and KKU-T23160 were identified as highly resistant. The second group, i.e., KKU-T23176, was identified as resistant and the other seven tomato cultivars were identified as moderately resistant. In addition, Ty-2, Ty-3, and Ty-4 gene were validated by 2 SCAR markers and 1 SSR marker in the 12 tomato accessions.