SlGSTU43 and SlERF-B12 Genes Are Involved in SlMYB15-Regulated Redox Homeostasis to Enhance Cold Tolerance in Tomato

Cold stress is a major abiotic factor limiting plant growth and productivity. MYB transcription factors are important regulators of stress responses. Our previous study identified SlMYB15 as a positive regulator of cold tolerance in tomato. However, their downstream regulatory mechanisms remained unclear. Herein, subcellular localization confirmed that SlMYB15 is a nuclearly localized transcription factor. Transcriptomic analysis revealed that SlMYB15 modulates genes involved in redox processes, hormone signaling, and glutathione metabolism under cold stress. SlMYB15 upregulated GSTU43, ERF-B12, CYP76A2-like, and CYP81D1-like, reducing ROS accumulation by enhancing antioxidant enzyme activities and modulating RBOH1-dependent H2O2 signaling. Silencing GSTU43 or ERF-B12 impaired the cold tolerance in SlMYB15-overexpressing plants. Furthermore, SlMYB15 activated the expression of GSTU43 and ERF-B12 by directly binding to the promoter regions. Collectively, these findings suggest that SlMYB15 enhances cold tolerance by regulating key redox-related genes, providing new insights into MYB-mediated stress resistance in tomato.