Phylogeny and cultivar development of Diospyros kaki: A survey based on molecular analyses

The relationships of Diospyros kaki to 14 Diospyros species, including D. glandulosa which was assumed as a progenitor of D. kaki by Ng (Malaysian Forester 41: 43-50), were studied by a combined data set of the sequences for ITS region and matK gene. Maximum parsimony, maximum likelihood, and neighbor joining analyses revealed that D. oleifera, a species native to China, was much closer to D. kaki than D. glandulosa. However, both D. oleifera and D. glandulosa were more closely related to D. kaki, compared with other species analyzed, indicating that these two diploid species might be involved in the origin of D. kaki, most of which is hexaploid. In addition, as for D. kaki, 102 Japanese, 20 Korean, and 24 Chinese cultivars were studied for their genetic relationships by comparing 496 AFLP markers to investigate cultivar development of D. kaki in Asia. An unrooted cladogram constructed by neighbor joining analysis indicated independent cultivar development in China, Korea, and Japan. Furthermore, pollination constant non-astringent (PCNA) type cultivars of Japanese origin were clearly separated from non-PCNA type cultivars in the cladogram, also indicating independent development of PCNA cultivars in Japan. Cultivar development of D. kaki in Asia is discussed further in the work, with focus on the astringency trait.