New candidate for the ancestor of Japanese persimmon ( diospyros kaki Thunb.) found in Yunnan province of China.

摘要

There are few reports for the origin of Japanese persimmon (Diospyros kaki) and no species is defined as ancestor for it. However, so far, D. glandulosa (syn. D. roxburghii) was reported as a candidate for the origin of persimmon by Ng (Malaysian Forester 41:43-50, 1978), and D. oleifera and D. lotus are also reported to have very close relationship to D. kaki in phylogenetic analyses using the sequences of matK gene of the chloroplast DNA and ITS region of the genomic DNA by our research (Tree Genetics & Genomes 4:149-158, 2008). These three candidate species are all diploid (2n=2x=30) in contrast that almost all of D. kaki is hexaploid (2n=6x=90). Recently, our survey of Diospyros species in China allowed us to find a new possible candidate of D. kaki, called "ye-mao-shi" in Chinese, in addition to these three candidate species. This new candidate seemed to be much closer to D. kaki than the previous three candidates due to morphological similarities of shape and size of leaf, fruit, and calyx. It was just like D. kaki in morphology, except that the fruit skin is pubescent in contrast with glabrous skin for D. kaki. The leaf surface of this new candidate is also a little bit pubescent. We found this candidate at Xishuangbanna Tropical Botanic Garden in Yunnan Province. According to the survey of specimens at the herbariums of Xishuangbanna Tropical Botanic Garden, Kunming Botanical Garden, Wuhan Botanical Garden, and Beijing Botanical Garden in China, this candidate was confused in the classification and was categorized into both D. kaki var. sylvestris and D. kaki. In fact, there were two types classified into D. kaki var. sylvestris and D. kaki; one has pubescent fruit skin and the other has glabrous fruit skin. The candidate having pubescent fruit skin, called "ye-mao-shi", should be classified as different categorization from D. kaki or D. kaki var. sylvestris. Interestingly, according to our herbarium survey in China, almost all of this candidate was distributed preferentially in Yunnan Province of China. Now, we are trying to analyze this new candidate to validate the genetic relationship to D. kaki in phylogenetic trees. This candidate should be closer to D. kaki among the species we analyzed and we are now planning to analyze the phylogenetic position of this new candidate among other wild Diospyros species we collected.