SlMYB17 Antagonises the SlCBF Pathway to Negatively Regulate Tomato Chilling Tolerance

Low temperature is a significant environmental constraint, impeding the extensive cultivation of tropical plants. Here, we identify the transcription factor SlMYB17 as an important negative regulator of tomato chilling tolerance. Overexpression of SlMYB17 significantly reduced chilling tolerance, whereas slmyb17 mutants exhibited enhanced tolerance. ChIP-seq analysis revealed that SlMYB17 targets genes involved in diverse biological processes and stress responses, suggesting its role in coordinating plant development and stress adaptation. SlMYB17 directly binds to the promoters of cold-regulated (COR) genes, such as SlCOR27b and WCOR413, thereby inhibiting their expression. Crucially, protein-protein interaction studies and Dual-LUC assays demonstrated that SlMYB17 interacts with SlCBF1, SlCBF2, and SlCBF3 in the nucleus to inhibit SlCBF-mediated activation of COR genes. Using virus-induced gene silencing (VIGS) targeting SlCBF1-3 in wild-type and slmyb17 mutants, we demonstrate genetically that SlMYB17's function in chilling tolerance is dependent on SlCBFs. Collectively, SlMYB17 antagonises the SlCBF pathway at both transcriptional and protein activity levels, ultimately suppressing tomato chilling tolerance. Our work establishes slmyb17 mutants as valuable genetic resources for developing chilling-tolerant tomato varieties, and the ChIP-seq data provide important insights for studying MYB transcription factors in stress responses and development.