A male determinant gene in diploid dioecious Diospyros, OGI, is required for male flower production in monoecious individuals of Oriental persimmon (D. kaki)

The sexuality of crops is an important trait affecting production and breeding efficiencies. Recently, a Y-chromosome-encoded gene, designated Oppressor of MeGI (OGI), has been shown to play a central role in dioecious sex determination in diploid persimmons (Diospyros spp.). However, little is known about the relationship between OGI and the irregular sexuality in polyploid persimmon (D. kaki). D. kaki, which is mostly hexaploid with some nonaploid individuals, is mainly constituted of monoecious and female individuals. In this study, we attempted to investigate the association of sexuality with OGI allele diversities/dosages in a wide range of D. kaki cultivars. The results indicated that OGI is indispensable for the monoecious phenotype producing male flowers, which suggested a conserved role for OGI as a key to expressing maleness in D. kaki, as in dioecious diploid Diospyros. However, the existence of OGI alleles did not always lead to production of male flowers in D. kaki. The dosage or composition of OGI alleles had no substantial effect on the sexuality of the cultivars tested. We discuss the potential use of the obtained information on OGI allele diversities/dosages for breeding of D. kaki cultivars.