MYB Transcription Factor CDC5 Activates <i>CBF3</i> Expression to Positively Regulate Freezing Tolerance via Cooperating With ICE1 and Histone Modification in <i>Arabidopsis</i>

The freezing temperature greatly limits the growth, development and productivity of plants. The C-repeat/DRE binding factor (CBF) plays a major role in cold acclimation, enabling plants to increase their freezing tolerance. Notably, the INDUCER OF CBF EXPRESSION1 (ICE1) protein has garnered attention for its pivotal role in bolstering plants' resilience against freezing through transcriptional upregulation of DREB1A/CBF3. However, the research on the interaction between ICE1 and other transcription factors and its function in regulating cold stress tolerance is largely inadequate. In this study, we found that a R2R3 MYB transcription factor CDC5 interacts with ICE1 and regulates the expression of CBF3 by recruiting RNA polymerase II, overexpression of ICE1 can complements the freezing deficient phenotype of cdc5 mutant. CDC5 increases the expression of CBF3 in response to freezing. Furthermore, CDC5 influences the expression of CBF3 by altering the chromatin status through H3K4me3 and H3K27me3 modifications. Our work identified a novel component that regulates CBF3 transcription in both ICE1-dependent and ICE1-independent manner, improving the understanding of the freezing signal transduction in plants.