Segregation of astringency in F₁ progenies derived from crosses between pollination-constant, nonastringent persimmon cultivars

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 F1 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 F1 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' x Japanese PCNA 'Taishu', Japanese PCNA 'Shinshu' x Japanese PCNA 'Taishu', and Japanese PVNA (non-PCNA) 'Kurokuma' x 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 x 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.