Effect of TSWV, TYLCV, FORL resistances on hybrid yield in tomato breeding

The aim of this study was to transfer TYLCV, TSWV, FORL resistance genes to the paternal parent of the (213♀x51♂) 17-52 F1 hybrid tomato by using molecular marker assisted back crossing method. The 17-52 hybrid is suitable for single season, spring and summer season production. Althought, it has a commercial potential in terms and quality, its susceptibility to related diseases halted its commercialization. We aimed to determine whether there is an effect on hybrid yield and fruit quality by transfering the relevant resistance genes. The susceptible elit line 51♂ was crossed with the triple (TYLCV, TSWV, FORL) heterozygous "4293 F1" resistant donor source. The seedlings of the first population (P.BC1 F1) were screened using molecular markers and the heterozygous resistant plant were selected to continue the backcrossing program. In the P.BC3 F1 generation, the plants carrying the single or double resistant Ty-3, Sw-5 genes and showing similarity to the elite line in terms of agronomic characters were selected and selfed. The P.BC3 F2 progenies were subjected to pathology testing for FORL. The individual P.BC3 F3 plants were obtained and selfed in this population. The 128 homozygous resistant plants that possess single or double resistance were identified with the help of molecular markers and crossed with the original maternal parent (213♀) of the 17-52 F1 hybrid. The 106 new resistant hybrids, morhphologically similar to17-52 F1 hybrid, were grown in the spring of 2021 in a replicated trial involving commercial hybrids. Yield and fruit quality data were collected and performances of new hybrids were evaluated against original 17-52 F1 hybrid. The result of the t-test showed that some of the most promising new hybrids are not different from the 17-52 F1 hybrid in terms of, the average yield values per plant, and fruit characteristics. The most promising resistant hybrids with commercialization potential were selected. A few of the new hybrids are expected to reach to market. KEYWORDS: TSWV, TYLCV, FORL, tomato breeding, backcross, hybrid yield, linkage drag