ADH and PDC genes involved in tannins coagulation leading to natural de-astringency in Chinese pollination constant and non-astringency persimmon (Diospyros kaki Thunb.)

Pollination constant non-astringency (PCNA)-type persimmons are the most desirable cultivar because the fruit loses astringency naturally and does not require any treatments for edibility. The mechanism of natural astringency loss in Chinese PCNA (C-PCNA)-type persimmon is probably related to the coagulation of soluble tannins into insoluble tannins, which is quite different from that in the Japanese PCNA (J-PCNA) type. In this work, three types of persimmon cultivars were sampled: ‘Luotian-tianshi’ (C-PCNA), ‘Maekawa-jirou’ (J-PCNA), and ‘Mopanshi’ (pollination constant astringent (PCA)) were sampled. Three DkADH and four DkPDC genes were isolated from C-PCNA plants. Three candidate genes for soluble tannins coagulation identified in C-PCNA fruit (DkADH1, DkPDC1, and DkPDC2) were characterized through combined analysis of spatiotemporal expression patterns and tannin and acetaldehyde contents during fruit development. Transient over-expression in persimmon leaves showed that DkADH1 and DkPDC2 led to a significant decrease in the levels of soluble tannins in infiltrated leaves. These results indicated that DkADH and DkPDC genes should be considered key genes for natural astringency loss in C-PCNA types.