VvbZIP22 regulates quercetin synthesis to enhances cold resistance in grape

Grapes are one of the important fruit crops widely cultivated in the world, with high nutritional and economic value. However, with the intensification of global warming, extreme low temperature has seriously affected the development of the grape industry. Quercetin is a highly antioxidant active substance that can enhance the tolerance of plants to external environmental stress, but its function and mechanism in response to low-temperature stress in grapes are still unclear. Here, we found that grapes accumulate more quercetin under low-temperature stress, and exogenous quercetin can significantly improve the cold resistance of grapes. The key quercetin synthesis gene VvFLS1 (flavanol synthase 1) is up-regulated after low-temperature treatment, and overexpression of VvFLS1 increases quercetin content and enhances the cold resistance of grape. Yeast one-hybrid and dual luciferase reporter systems demonstrate that VvbZIP22 (basic-leucine zipper 22) directly binds to the VvFLS1 promoter, and VvbZIP22 has cold-induced expression characteristics. Overexpression of VvbZIP22 significantly improves the cold resistance of grape. The above results indicate that quercetin plays an important role in the response of grapes to low-temperature stress. Under low temperature, VvbZIP22 can mediate quercetin synthesis through regulating VvFLS1, alleviate oxidative damage, and improve the cold resistance of grapes.