AUTHOR=Song Zhaopeng , Luo Yong , Wang Weifeng , Fan Ningbo , Wang Daibin , Yang Chao , Jia Hongfang 

TITLE=NtMYB12 Positively Regulates Flavonol Biosynthesis and Enhances Tolerance to Low Pi Stress in Nicotiana tabacum

JOURNAL=Frontiers in Plant Science

VOLUME=10

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.01683

DOI=10.3389/fpls.2019.01683

ISSN=1664-462X

ABSTRACT=<p>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, <italic>NtMYB12</italic>, whose expression was significantly up-regulated under low Pi conditions. Overexpression of <italic>NtMYB12</italic> dramatically increased flavonol concentration and the expression of certain flavonol biosynthetic genes (<italic>NtCHS</italic>, <italic>NtCHI</italic>, and <italic>NtFLS</italic>) in transgenic tobacco. Moreover, overexpression of <italic>NtMYB12</italic> also increased the total P concentration and enhanced tobacco tolerance of low Pi stress by increasing the expression of <italic>Pht1</italic>-family genes (<italic>NtPT1</italic> and <italic>NtPT2</italic>). We further demonstrated that <italic>NtCHS-</italic>overexpressing plants and <italic>NtPT2-</italic>overexpressing plants also had increased flavonol and P accumulation and higher tolerance to low Pi stress, showing a similar phenotype to <italic>NtMYB12</italic>-overexpressing transgenic tobacco under low Pi stress. These results suggested that tobacco <italic>NtMYB12</italic> acts as a phosphorus starvation response enhancement factor and regulates <italic>NtCHS</italic> and <italic>NtPT2</italic> expression, which results in increased flavonol and P accumulation and enhances tolerance to low Pi stress.</p>