Preliminary study on mapping of genes controlling staminate flower expression and QTL analysis of the ratio of pistillate flowers in melon (Cucumis melo L.).

Melon (Cucumis melo L.) displays a range of sexual phenotypes including various combinations of male, female, or bisexual flowers. Gynoecious sex expression is of great value in heterosis breeding in melon (Cucumis melo L.) because artificial emasculation can partially be avoided and hybrid purity can be ascertained. The gynoecious melon line WI998 was crossed as female parent with the monoecious melon line 3-2-2 as male parent. The F 2 population was used for linkage analysis to map gene a using SSR markers. The resulting map consisted of 5 linkage groups with 18 SSR markers and one morphological marker. It spanned a total of 442.7 cM of genetic distance with a 24.6 cM average interval. Two SSR markers, MU4128-2 and MU5028-1 flanking gene a with the distance at 42.8 and 26 cM, respectively. Two QTL named FP 2.1 (female percentage 2.1) and FP 2.2 (female percentage 2.2) were located in linkage group 3. The ratio of dominant and additive effect of FP 2.1 and FP 2.2 were 1.19 and 1.09, respectively. The location information of gene a which controlling presence of staminate and pistillate flower quantitative trait locus in melon should have great value on sex expression research in cucurbits.