Improvement of resistance to late blight in hybrid tomato

Abstract

Late blight is one of the major diseases in tomato cultivated both in the greenhouse and the field. In this work, we determined the resistance levels of all progeny lines (F₁ to F₃) and a new variety (NV) F₁ to the late blight disease fungus to evaluate these hybrid lines as potential sources of resistance. The experiments were carried out in greenhouse conditions in a completely randomized block design with three replications. Fifteen out of 204 F₂ plants of cross A (AV107-4 × L3708) and 13 out of 203 F₂ plants of cross B (Campari × 917 × L3708) were found to be resistant to late blight in combined data from greenhouse trials. In addition, 5 resistant F₃ lines derived from each of the two crosses A and B were selected for further investigation. By screening the NV F₁ hybrids obtained by pollination of the F₃ lines by 3 male-sterile cultivars (Wonung-1, 2, and 3), two stable resistant hybrids, Wonung-2 × A120 and Wonung-3 × B23, were finally produced. An examination of the qualitative characters in the NV F₁ hybrids indicated improved fruit weight and quality. Taken together, our screening results indicate that both of these hybrids are good sources of resistance and have high-value horticultural characters, which can be used for tomato breeding programs.