Genetic analysis and QTL mapping of fruit-related traits in wax gourd (Benincasa hispida)

As an important fruit vegetable, fruit-related traits have become one of the breeding hotspots of wax gourd (Benincasa hispida). The fruit traits have an important role on the quality and yield of wax gourd, and QTL mapping of these traits will provide solid basis for fruit character improvement as well as high-yield breeding. In this study, the inheritance of four fruit-related traits, including fruit weight (FW), fruit length (FL), fruit diameter (FD) and flesh thickness (FT), was analyzed. All the frequency distribution of the four traits in an F-2 population showed a single peak skewed distribution, which proved them to be quantitative. Subsequently, based on the high-density genetic map using 140 F-2 individuals, nine QTLs associated with the four traits were detected on chromosome 3, 4, 5, 6, 9, 10 and 11. Four of the nine QTLs had major effect, which were responsible for more than 10.0% of phenotypic variance. Furthermore, the major QTLs of FW, FD and FT shared similar location intervals, which implied that this location might contain some pleiotropic genes. This is the first report on QTL mapping of quantitative trait in wax gourd, which plays an important role for fine mapping of these important fruit traits.