Sex Expression and Flower Morphogenesis in ‘84 apple sherbet’ Cucumber (Cucumis sativus) Carrying the mm Genotype with the c.97G > T Mutation in the CS-ACS2 Gene

The andromonoecious cucumber cultivar ‘Lemon’ (mmff; Cucumis sativus L.) produces male flowers and bisexual flowers with short ovaries on the same plant. Our previous studies showed that some ‘Lemon’ (mmff) plants and their progeny from crosses with the gynoecious cultivar ‘Dokanari-sennari’ (MMFF) also produced female flowers with short ovaries resembling bisexual flowers under standard cultivation conditions. This phenotype was mainly observed in plants carrying the mm genotype with the c.97G > T mutation in the CS-ACS2 gene. In ‘Lemon’ plants, female flowers with short ovaries appeared only after male and bisexual flowers, and this pattern was defined as a novel trimonoecious phenotype. In this study, we examined another andromonoecious cultivar, ‘84 apple sherbet’, under controlled growth conditions. Molecular marker analysis and DNA sequencing confirmed the mmff genotype. Five of six plants produced female flowers with short ovaries in addition to male and bisexual flowers. Unlike ‘Lemon’, some plants developed female flowers at an early developmental stage. These results indicate that this trimonoecious phenotype occurs in cultivars other than ‘Lemon’ and suggest that the mm genotype contributes to the formation of both bisexual and female flowers with short ovaries in cucumber.