The zinc-finger transcription factor ZAT6 is essential for hydrogen peroxide induction of anthocyanin synthesis in Arabidopsis.

The accumulation of flavonoids is activated by various abiotic stresses, and the induction of reactive oxygen species (ROS) especially hydrogen peroxide (HO) is a general response to abiotic stress in plants. However, the direct link between flavonoids and HO and underlying mechanism remain elusive. In this study, we found that the concentrations of anthocyanin and flavonoids were significantly induced by HO treatment. Furthermore, we found that the transcript level of ZINC FINGER of ARABIDOPSIS THALIANA 6 (ZAT6) was significantly activated after exogenous HO treatment, and modulation of AtZAT6 expression positively affected the concentrations of both anthocyanin and total flavonoids. Notably, exogenous HO-induced anthocyanin synthesis was largely alleviated in AtZAT6 knockdown plants, but showed higher level in AtZAT6 overexpressing plants. AtZAT6 directly activated the expressions of TT5, TT7, TT3, TT18, MYB12, and MYB111 through binding to their promoters with TACAAT elements of these genes, and the activation of MYB12 and MYB111 up-regulated the expressions of TT4 and TT6. Taken together, this study indicates that AtZAT6 plays important role in HO-activated anthocyanin synthesis, via directly binding to the promoters of several genes that involved in anthocyanin synthesis.