Abstract
The resistance to tomato yellow leaf curl disease was evaluated and analyzed in tomato plants of CLN2498E (source of resistance), Castle Rock, and their progenies F-1, F-2 and BC1F1 populations using a sequence tagged site marker, linked to Ty-2 gene (T0302). Three viral strains (TYLCV-Has, TYLCV-IL and TYLCV-Pep) were used for segregation of resistance and disease evaluation for both parents and their progenies. Results showed that CLN2498E carried Ty-2 gene marker but Castle Rock did not have this resistance gene. The F-2 and BC1F1 plants were segregated for Ty-2 with ratio closed to 3:1 (X-2 =0.86) and 1:1 (X-2 =0.60), respectively. These ratios indicated that Ty-2 gene was simply inherited into the F-2 and BC1F1. The phenotypic screening results showed that the resistance to infection was dependent on the type of viral strain. The line CLN2498E was resistant to TYLCV-Has and TYLCV-IL while Castle Rock was susceptible. The plants those have Ty-2 gene homozygous (Ty-2/Ty-2) or heterozygous (Ty-2/ty2) were resistant to TYLCV-Has and TYLCV-IL while the plants did not carry Ty-2 gene were susceptible for both strains. In contrast, all the plants were susceptible to TYLCV-Pep even if they were carrying the resistance gene (Ty-2).