Positively Regulates Flavonol Biosynthesis and Enhances Tolerance to Low Pi Stress in .

Phosphorus (P) is an essential macronutrient for plant growth and development. The concentration of flavonol, a natural plant antioxidant, is closely related to phosphorus nutritional status. However, the regulatory networks of flavonol biosynthesis under low Pi stress are still unclear. In this study, we identified a PFG-type MYB gene, , whose expression was significantly up-regulated under low Pi conditions. Overexpression of dramatically increased flavonol concentration and the expression of certain flavonol biosynthetic genes (, , and ) in transgenic tobacco. Moreover, overexpression of also increased the total P concentration and enhanced tobacco tolerance of low Pi stress by increasing the expression of -family genes ( and ). We further demonstrated that overexpressing plants and overexpressing plants also had increased flavonol and P accumulation and higher tolerance to low Pi stress, showing a similar phenotype to -overexpressing transgenic tobacco under low Pi stress. These results suggested that tobacco acts as a phosphorus starvation response enhancement factor and regulates and expression, which results in increased flavonol and P accumulation and enhances tolerance to low Pi stress.