Synergistic Interaction Between VyMYB24 from Chinese Wild Grape Vitis yeshanensis and Cytokinin Enhances Cold Tolerance in Transgenic Tobacco

Low temperatures severely restrict plant growth and agricultural productivity, and exploring cold tolerance mechanisms is critical. This study investigated the combined effects of grape-derived transcription factor gene VyMYB24 and the synthetic cytokinin CPPU on cold tolerance in transgenic tobacco. Under low-temperature stress, tobacco plants overexpressing VyMYB24 and treated with CPPU exhibited significantly alleviated wilting, higher chlorophyll contents, and an improved net photosynthetic rate compared to controls. These plants also showed a lower relative conductivity and malondialdehyde (MDA) content, higher proline accumulation, and elevated activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), accompanied by reduced reactive oxygen species (ROS), hydrogen peroxide (H2O2), and superoxide anions (O2·-). The results confirm that VyMYB24 and CPPU synergistically improve cold tolerance via membrane stabilization, enhanced antioxidant defense, and maintained photosynthetic capacity, providing a theoretical foundation for the rational application of CPPU in the cultivation and management of grapes under low-temperature conditions.