Segregation of Astringency in F1 Progenies Derived from Crosses between Pollination-constant, Nonastringent Persimmon Cultivars

Abstract

Japanese persimmon ( Diospyros kaki Thunb.) cultivars are classified into four types depending on the nature of astringency loss of the fruit. The pollination-constant, non-astringent (PCNA) persimmons lose their astringency on the tree as the fruits develop. This PCNA trait is qualitatively inherited and recessive to the other three types, pollination-constant, astringent (PCA), pollination-variant, nonastringent (PVNA), and pollination-variant, astringent (PVA). In fact, crosses among Japanese PCNA cultivars yield only PCNA type in F 1 generation as shown in recent breeding programs at the National Institute of Fruit Tree Science. Despite these previous results, we demonstrated here that non-PCNA (PVNA, PVA, and PCA) type offspring were derived at relatively high rates in the F 1 generation from a cross between `Luo Tian Tian Shi', a PCNA accession from China, and the Japanese PCNA cultivar, `Taishu', despite the fact that `Luo Tian Tian Shi' was confirmed to be a true PCNA type by measuring tannin cell size, a principal morphological characteristic to distinguish PCNA cultivars from non-PCNA ones. When segregations of tannin cell size and tannin content in three progenies of the breeding populations derived from Chinese PCNA `Luo Tian Tian Shi' × Japanese PCNA `Taishu', Japanese PCNA `Shinshu' × Japanese PCNA `Taishu', and Japanese PVNA (non-PCNA) `Kurokuma' × Japanese PCNA `Taishu' were investigated, all offspring between Japanese PCNA cultivars contained only small tannin cells and were PCNA types, and those between Japanese PVNA × PCNA cultivars contained only large tannin cells and were non-PCNA types. However, hybrids between `Luo Tian Tian Shi' and `Taishu' segregated into populations of small and large tannin cells, indicating that `Luo Tian Tian Shi' is likely heterozygous for astringency. Therefore, Chinese PCNA `Luo Tian Tian Shi' should be different from Japanese PCNA cultivars in genetic makeup.