ALDH2 genes are negatively correlated with natural deastringency in Chinese PCNA persimmon ( Diospyros kaki Thunb.)

Chinese pollination-constant and non-astringent persimmon (C-PCNA) has important application values in the genetic improvement of PCNA for its trait of natural deastringency controlled by a single dominant gene. However, the key genes and the regulatory networks are still not fully understood. The process of C-PCNA natural deastringency may be associated with the acetaldehyde-mediated coagulation of soluble tannins, but the functions of ALDH2 genes related to the metabolism of acetaldehyde are not clear. In this work, three types of persimmon cultivars, ‘Eshi 1’ and ‘Luotian Tianshi’ (C-PCNA type), ‘Youhou’ (J-PCNA type), and ‘Mopanshi’ (non-PCNA type), were sampled. Two members of ALDH2 family genes, DkALDH2a and DkALDH2b , were isolated from ‘Eshi 1’ persimmon fruit. Gene expression patterns indicated that they may be involved in “coagulation effect”, which leads to natural deastringency in C-PCNA persimmon fruit. Transient expression in ‘Eshi 1’ leaves further demonstrated that their expression can reduce the consumption of soluble tannins and inhibit the astringency removal process. Therefore, DkALDH2a and DkALDH2b are negatively correlated with natural deastringency in C-PCNA persimmon.