Posttranslational regulation of multiple clock-related transcription factors triggers cold-inducible gene expression in Arabidopsis

Significance The DREB1/CBF transcription factors function as master switches for cold stress adaptation in Arabidopsis . Cold stress strongly induced the DREB1 genes, and elucidation of the mechanisms of DREB1 induction is important to clarify the cold stress responses in plants. We revealed that the clock-related MYB proteins RVE4 and RVE8 were quickly transferred from the cytoplasm to the nucleus in response to cold stress and functioned as direct transcriptional activators of DREB1 expression. The other clock-related MYB proteins, CCA1 and LHY, suppressed DREB1 expression under unstressed conditions and were rapidly degraded under cold stress, which suggests that these factors indirectly regulate cold-inducible DREB1 expression. We concluded that posttranslational regulation of the clock-related transcription factors triggered cold-inducible gene expression.