Proanthocyanidins (PAs) are secondary metabolites that contribute to important plant traits like fruit astringency. Persimmon (Diospyros kaki Thunb.) is unique for accumulating abundant PAs in its fruit flesh. Two non-astringent-type mutants, namely, Japanese pollination-constant and non-astringent (J-PCNA) and Chinese PCNA (C-PCNA), were unable to accumulate PA naturally on the tree before harvest. It was clear that the decreased expression profile of a Myb transcription factor (TF) DkMyb4 in persimmon fruits results in the PCNA trait in J-PCNA mutant. However, the mechanism leading to the PCNA trait in C-PCNA mutant remains unclear. In this study, with the purpose of figuring out whether or not there was a certain Myb TF resulting in PCNA trait in C-PCNA mutant, a gene homologous to DkMyb4 was isolated from C-PCNA cultivar ‘Luotian-tianshi’, named DkPA1. Bioinformatics analysis showed that DkPA1 shared high similarity to DkMyb4 in amino acid level, and that DkPA1 was phylogenetically closer to PA-related Myb TFs. Expression pattern of DkPA1 coincided with expression of PA pathway genes, also consistent with PA accumulation model in both C-PCNA and non-PCNA fruit during fruit development. Though being absent in J-PCNA, we found there were MYBCORE cis-motifs in promoter of PA pathway Leucoanthocyanidin reductase (DkLAR) gene isolated from C-PCNA and non-PCNA, which was reported as a key cis-element for PA biosynthesis and target of Myb TFs. These results suggested that DkLAR was regulated by DkPA1 in C-PCNA and non-PCNA, it played much more important role in C-PCNA and non-PCNA PA biosynthesis than that in J-PCNA.
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