Molecular isolation of the M gene suggests that a conserved-residue conversion induces the formation of bisexual flowers in cucumber plants

Sex determination in plants involves a variety of mechanisms. Here, we report the map-based cloning and characterization of the unisexual-flower-controlling gene M. M was identified as a previously characterized putative 1-aminocyclopropane-1-carboxylic acid synthase gene, while the m allele that mutated at a conserved site (Gly33Cys) lost activity in the original enzymatically active allele.