Inheritance and molecular mapping of andromonoecious and gynoecious sex determining genes in melon (Cucumis melo L.)

The inheritance of sex determination genes in melon was studied using the populations of F1, F2, BC1P1 and BC1P2 derived from two parental lines, the gynoecious WI998 and andromonoecious TopMark. These populations were segregating at two loci for sex determination: the a gene locus for andromonoecious and the m gene locus for gynoecious sex expression. It was found that different phenotypes corresponded to different genotypes in sex expression: A-G- = monoecious; A-gg = gynomonecious; aaG- = andromonoecious; aagg = hemaphrodite; and A-ggmm = gynoecious. A preliminary genetic mapping of these two gene loci were conducted with microsatellite markers in the F2 population with 298 individuals. Fifty-five polymorphic SSR markers were identified and applied for linkage analysis to construct the genetic map which spanned 666.7 cM with a mean marker interval of 17.09 cM. SSR marker MU5549-1 linked to gene a with the distance at 13.5 cM and SSR marker MU14723-2 linked to gene m with the distance at 11.6 cM.