DkMYB14 is a bifunctional transcription factor that regulates proanthocyanindin accumulation in persimmon fruit.

Proanthocyanidins (PAs) are phenolic secondary metabolites that contribute to the protection of plant and human health. Persimmon (Diospyros kaki Thunb.) can accumulate abundant PAs in fruit, which cause a strong astringent sensation. PAs can be classified into soluble and insoluble PAs; the former cause astringency but the latter does not. Soluble PAs can be converted into insoluble PAs when interacting with acetaldehydes. We demonstrate here that DkMYB14, which regulates PA accumulation in persimmon fruit flesh, is a bifunctional transcription factor that acts as a repressor in PA biosynthesis but becomes an activator when involved in acetaldehyde biosynthesis. Interestingly, both functions contribute to the elimination of astringency by decreasing PA biosynthesis and promoting PA insolubilization. We show that the amino acid of Gly39 in the R2 domain and the EAR-like motif in the C-terminus of DkMYB14 are essential for the regulation of both PA and acetaldehyde synthesis. The repression function of DkMYB14 was lost after the mutation of either motif, and all activities of DkMYB14 were eliminated following the mutation of both motifs. Our results demonstrate that DkMYB14 functions both as a transcriptional activator and repressor, directly repressing PA biosynthesis and promoting PA insolubilization, resulting in non-astringency in persimmon.