Fine genotyping of a highly polymorphic ASTRINGENCY-linked locus reveals variable hexasomic inheritance in persimmon (Diospyros kaki Thunb.) cultivars

Persimmon (Diospyros kaki Thunb.) is one of the major tree crops in East Asia and is generally hexaploid. A single ASTRINGENCY (AST) locus controls the astringency/non-astringency (A/NA) trait of persimmon fruit, one of the most important traits for consumption, on each of the six corresponding chromosomes. Although several molecular approaches are in progress to elucidate the molecular mechanisms of astringency trait in persimmon, the distinct polysomic behavior of the AST locus remains to be solved. The aim of this study was to perform fine genotyping of a highly polymorphic marker locus linked to the AST locus, detect the allele pairing in ten segregated F(1) lines derived from hybridization of A-type x NA-type cultivars, and identify the basis of hexaploid inheritance at the AST locus in persimmon. The results showed that persimmon cultivars frequently produce aneuploid offspring bearing an extra chromosome with the AST locus, with the incidence of aneuploidy varying among the cultivars. On the examination of hexasomic behavior in persimmon cultivars, the ratios of individuals bearing each allele pair segregated from A-type parents showed a good fit to the expected ratios in an autohexaploid inheritance model, except for cvs. Luo-tian-tian-shi and Sa-gok-shi which fitted to an autoallohexaploid inheritance model. These results suggest variable hexasomic behavior among persimmon cultivars.