CIRCADIAN CLOCK-ASSOCIATED1 Delays Flowering by Directly Inhibiting the Transcription of in Pak-choi.

Flowering is critical to the success of plant propagation. The MYB family transcription factor () is an essential component of the core loop of the circadian clock and plays a crucial role in regulating plant flowering time. In this study, we found that photoperiod affects the expression pattern and expression level of , which is delayed flowering time under short-day conditions in Pak-choi [ (. ) ssp. ]. We detected overexpression and silencing of in Pak-choi, resulting in delayed and promoted flowering time, respectively. Furthermore, we also discovered that () and () were expressed significantly differently in overexpression and silencing plants compared with control plants. Therefore, we further investigated the interaction relationship between , , and , and the results showed that and as a complex interacted with each other. Moreover, both BcCCA1 and BcFLC can directly bind to the promoter of and repress its transcription, and BcCCA1 can form a complex with BcFLC to enhance the transcriptional inhibition of by BcFLC. This study reveals a new mechanism by which the circadian clock regulates flowering time.