Survey of ancestral species of persimmon (Diospyros kakiThunb.) and considering the process for appearance of pollination constant non-astringent (PCNA)-type persimmon.

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The purpose of this study is 1) to clarify whether pollination constant non-astringent (PCNA) persimmons exist in China except for 'Luo Tian Tian Shi', in addition to clarify an uniqueness of `Luo Tian Tian Shi', and 2) to survey ancestral species of persimmon (Diospyros kaki Thunb.). For this purpose, we conducted the following investigations:1)We constructed survey trips to Luotian county in Hubei province, where 'Luo Tian Tian Shi' was found. As the results, we were able to find new PCNA cultivars named `Qiuyan Tian Shi', 'Baogai Tian Shi', and 'Xiaoguo Tian Shi'. In addition, we were able to investigate the original tree of `Luo Tian Tian Shi', which showed us `Luo Tian Tian Shi' originated from a seedling.2)The uniqueness of PCNA trait in `Luo Tian Tian Shi' was clarified to investigate the F_1 progenies derived from crossings between 'Luo Tian Tian Shi' and Japanese PCNA or non-PCNA cultivars. In F_1 progenies from all crossings, PCNA and non-PCNA individuals were segregated at the ratio of 1:1. It means that the trait of Chinese PCNA is dominant. It is quite different from recessive trait of Japanese PCNA.3)As for consideration of ancestral species of persimmon, the survey of specimens was conducted in Botanical Garden in Kunming, Wuhan, and Beijing. We found an interesting species named "ye mao shi" classified as Diospyros kaki var. sylvestris. This species has a pubescent fruit surface, while wild persimmon (D. kaki) named "ye shi" has glabrous fruits. The morphological characteristic of "ya mao shi" was very similar to D. galndulosa, which is supposed to be a progenitor of D. kaki. We also could find the trees of this species in the forest of Xishuangbanna Tropical Botanical Garden, the Chinese Academy of Science.