Repression of <scp> <i>DkALDH10</i> </scp> by <scp>microRNA143c</scp> promotes astringency loss in Chinese <scp>PCNA</scp> persimmon

Persimmon fruits accumulate substantial amounts of proanthocyanidins (PAs), with soluble PAs causing a dry or puckering sensation in the mouth when consumed. Acetaldehyde, an important volatile compound, reacts with soluble PAs to form insoluble PAs, leading to the natural deastringency of the fruits of the Chinese Pollination Constant Non-astringent (C-PCNA) persimmon at ripening. In this study, a DkALDH (aldehyde dehydrogenase) gene belonging to subfamily 10 was revealed to be localized to the tonoplast and plasma membrane. Following transient expression experiments, we observed that DkALDH10 negatively regulates the conversion of soluble PAs into insoluble PAs. Furthermore, the stable transformation of DkALDH10 confirmed that its overexpression reduced the acetaldehyde content and thereby inhibited the conversion of soluble PAs into insoluble PAs, whereas the silencing of DkALDH10 increased the acetaldehyde content and consequently promoted the conversion of soluble PAs into insoluble PAs. Notably, microRNA143c from the small RNA libraries of 'Eshi 1' (C-PCNA) fruit was predicted to target the DkALDH10 gene. The expression patterns of the transcripts of miR143c and DkALDH10 differed during the full fruit development stages of 'Eshi 1', and miR143c could cleave DkALDH10 at positions 10-11 bp according to RLM-5' RACE analysis and GFP signal detection. Transient expression and stable transformation experiments demonstrated that miR143c negatively regulates the expression of DkALDH10, thereby influencing the conversion of soluble PAs into insoluble PAs through the modulation of acetaldehyde levels in persimmon. Collectively, our results indicate that miR143c suppresses the expression of DkALDH10, positively regulating the natural deastringency of C-PCNA persimmon. This finding provides a potential strategy for genetically manipulating the deastringency of C-PCNA persimmon fruit.