Breeding of tomato lines resistant to tomato yellow leaf curl virus (Ty-3) and tomato spotted wilt virus (Sw-5) by molecular marker assisted backcrossing method

Various viruses cause significant yield and quality losses in tomato production. The aim of this study is; to provide resistance to the related viruses to the parent line of the indeterminate table tomato variety candidate suitable for spring cultivation, which has commercialization potential in terms of yield and quality characteristics but is sensitive to two important virus factors. Genes giving resistance to Tomato Spotted Wilt Virus and Tomato Yellow Leaf Curl Virus were transferred to one of the parent lines by a marker-assisted backcrossing program. For this, the parent line numbered "51" sensitive to TYLCV and TSWV was hybridized with hybrid numbered "202 F1" the donor carrying double resistance. The first population obtained (pseudo-BC1F1) was screened with molecular markers at the seedling stage. Plants bearing Ty-3 and Sw-5 were grown in the greenhouse. "51" is backcrossed to the repeated parent. Seedlings were grown again from BC2F1 seeds obtained from plants superior in terms of herbal and agronomic characters and the above procedures were repeated. BC2F1 plants exhibiting double virus resistant repeat parent characteristics were inbred and homozygous double virus resistant BC2F2 plants were obtained. Double strength (Ty-3 and Sw-5) plants were identified with the help of relevant molecular markers and brought up to BC2F2 stage. 12 plants that carry genes homozygous to Ty-3 and Sw-5 will be used instead of the repeated parent and will be used in the development of double virus resistant hybrid tomato candidates. Developing dual strength lines using molecular markers linked to the Ty-3 and Sw-5 genes will enable the development of native resistant varieties against TYLCV and TSWV viruses that cause significant economic losses in tomato. Parental lines carrying the Sw-5 and Ty-3 genes were developed using marker-assisted selection methods. With the commercialization of hybrids carrying resistance genes, the yield and quality losses caused by these factors will be prevented.