Genetic analysis of resistance to Fusarium oxysporum f. sp. niveum race 2 in cultivated watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai]

The genetics and nature of gene action involved in resistance to Fusarium oxysporum f. sp. niveum race 2 causing wilt in watermelon was studied. Five resistant accessions were crossed with a common susceptible parent to develop six generations for each combination. The populations were screened in two consecutive assays during June to September 2019. Based on the segregation of F-2, the resistance in IC0523048, EC794455 and EC759804 was found to be governed by two major complementary dominant genes. However, the deviation from the expected ratio in BC1 progeny suggested the involvement of modifying genetic factors. The F-2 and backcross progenies of BIL-53 x IIHR-9 and BIL-53 x EC794421 did not follow any of the ratios tested. Allelism test revealed the absence of any allelic relationship between IIHR9 and IC0523048 for resistance. Generation mean analysis revealed presence of epistasis in BIL-53 x EC794455 and BIL-53 x EC759804 while in the other three crosses, simple additive-dominance interaction was observed. These resistant accessions and the inheritance information generated in this study would help in incorporation of resistance to Fusarium wilt race 2 into elite commercial backgrounds.