QTL-seq identifies major quantitative trait loci of stigma color in melon

Stigma color plays an important role in pollination. In nature, melon (Cucumis melo L.) stigmas are either yellow or green; however, a review of the literature found no report on how stigma color affects pollination and fruit development in melon. Here, we used an F2 melon population derived from a cross between ‘MR-1’ (P1, with green stigmas) and ‘M1–32’ (P2, with yellow stigmas), and performed genetic analysis and mapping. The results of bulked segregant analysis allowed the identification of genetic loci controlling stigma color on chromosomes 6 and 8. An F2 population consisting of 150 individuals was used for initial mapping. A genetic map of 304.17 cM was constructed using 37 cleaved amplified polymorphism sequence (CAPS) markers. We identified one major quantitative trait locus (QTL) and one minor QTL for stigma color. The major QTL GS8.1 was further mapped to a 4.13 cM interval between CAPS markers 8C-10 and 8C-16, which explained 27.04% of the phenotypic variation. In addition, GS6.1 was mapped between E-49 and 6A-7, explaining 18.6% of the phenotypic variation. This study provides a theoretical basis for the fine mapping and cloning of melon genes controlling stigma color.