Appropriate induction of TOC1 ensures optimal MYB44 expression in ABA signaling and stress response in Arabidopsis.

Plants possess the remarkable ability to integrate the circadian clock with various signalling pathways, enabling them to quickly detect and react to both external and internal stress signals. However, the interplay between the circadian clock and biological processes in orchestrating responses to environmental stresses remains poorly understood. TOC1, a core component of the plant circadian clock, plays a vital role in maintaining circadian rhythmicity and participating in plant defences. Here, our study reveals a direct interaction between TOC1 and the promoter region of MYB44, a key gene involved in plant defence. TOC1 rhythmically represses MYB44 expression, thereby ensuring elevated MYB44 expression at dawn to help the plant in coping with lowest temperatures during diurnal cycles. Additionally, both TOC1 and MYB44 can be induced by cold stress in an Abscisic acid (ABA)‐dependent and independent manner. TOC1 demonstrates a rapid induction in response to lower temperatures compared to ABA treatment, suggesting timely flexible regulation of TOC1‐MYB44 regulatory module by the circadian clock in ensuring a proper response to diverse stresses and maintaining a balance between normal physiological processes and energy‐consuming stress responses. Our study elucidates the role of TOC1 in effectively modulating expression of MYB44, providing insights into the regulatory network connecting the circadian clock, ABA signalling, and stress‐responsive genes. Summary statement: We present initial evidence that MYB44, a key player in the ABA signalling pathway, is directly targeted by the circadian clock. Additionally, our findings offer a comprehensive understanding of the TOC1‐MYB44 module, elucidating its crucial role under both ABA‐dependent and ABA‐independent conditions during cold stress. [ABSTRACT FROM AUTHOR]