Gibberellins negatively regulate low temperature-induced anthocyanin accumulation in a HY5/HYH-dependent manner.

Low temperature could significantly induce anthocyanin accumulation in the presence of light. Recently, two bZIP transcription factors LONG HYPOCOTYL 5 (HY5) and HOMOLOG OF HY5 (HYH) were identified to play an important role in the process of low temperature-induced anthocyanin accumulation. However, the mechanism by which HY5/HYH regulates anthocyanin accumulation under low temperature still remains unclear. Here, we found that the gibberellins (GAs) could decrease but PAC (endogenous GAs biosynthesis inhibitor) increase the low temperature-induced anthocyanin accumulation, implying that GAs signaling may involve in this process. Furthermore, the transcript levels of GA2ox1, encoding a major member of bioactive GAs-deactivating enzymes, were significantly up-regulated by low temperature in a HY5/HYH-dependent manner. Moreover, hy5hyh mutant was insensitive to PAC in enhancing anthocyanin accumulation under low temperature. From these data we propose that, together with HY5/HYH, GA signaling may play an important role during low temperature-induced anthocyanin accumulation.