Isolation and characterization of a basic Helix-Loop-Helix transcription factor gene potentially involved in proanthocyanidin biosynthesis regulation in persimmon (Diospyros kaki Thunb.)

Persimmon (Diospyros kaki Thunb.) fruits accumulate abundant proanthocyanidins (PAs) which can protect plants against herbivore and UV irradiation, contribute to the taste of many fruits, and act as antioxidants that are beneficial to human health. Previous studies indicated that, basic Helix-Loop-Helix (bHLH) transcription factors, such as AtTT8 and VvMYC1, regulated PA biosynthesis in Arabidopsis and grape respectively. Here, we had cloned and characterized a bHLH gene (DkMYC1) from 'Luotian-tianshi'. persimmon. Phylogenetic analysis of the DkMYC1 protein sequence showed it shared high similarity with AtTT8 and VyMYC1. The expression profile of DkMYC1 was analyzed in two pollination-constant non-astringent (PCNA) type persimmon cultivar fruits with different molecular mechanisms for PA accumulation, and one astringent (non-PCNA) type persimmon by quantitative real-time PCR (qRT-PCR) analysis during fruits development. Results showed the expression pattern of DkMYC1 was correlated with PA accumulation in the two PCNA and the non-PCNA cultivars during fruits development and the expression of biosynthetic genes which were involved in PA biosynthesis. These results indicated that DkMYC1 may be an important bHLH transcription factor regulating PA biosynthesis in persimmon. This is the first report of a bHLH transcription factor gene involved in PA biosynthesis in persimmon. (c) 2012 Elsevier B.V. All rights reserved.