PgF3H gene enhances drought tolerance in transgenic Arabidopsis by regulating flavonoid biosynthesis and stress response

Water stress significantly impairs plant growth and yield, but plants combat this through various strategies, including flavonoid biosynthesis regulation. Flavonoids, crucial secondary metabolites, aid in plant development and stress responses. Pearl millet, a drought-tolerant crop, produces high levels of secondary metabolites like flavonoids and anthocyanins via the phenylpropanoid pathway. Research indicates that flavonoid-encoding genes are prevalent in drought-tolerant pearl millet variants, hinting at their role in drought response, though their exact functions are not fully understood. This study highlights the essential role of pearl millet flavanone 3-hydroxylase ( PgF3H ) in flavonoid biosynthesis. Overexpressing PgF3H in Arabidopsis enhances flavonol and anthocyanin content, improving tolerance to water-deficit stress without affecting antioxidant gene expression. Supporting evidence includes increased flavanone 3-hydroxylase activity in the Atf3h mutant and variable anthocyanin levels in Atans and Atanr mutants. In silico analysis of the PgF3H promoter revealed stress-responsive elements, and ProPgF3H::GUS expressing lines showed increased GUS expression with higher PEG concentrations. The in silico structure of PgF3H revealed a 2OG-Fe(II) oxygenase domain, crucial in the flavonoid biosynthetic pathway. In conclusion, PgF3H overexpression enhances drought tolerance in Arabidopsis , suggesting a potential strategy for improving crop drought resistance by manipulating flavonoid biosynthesis.