Poplar MYB117 promotes anthocyanin synthesis and enhances flavonoid B-ring hydroxylation by up-regulating the flavonoid 3′,5′-hydroxylase gene

Abstract Flavonoids, such as anthocyanins, proanthocyanidins, and flavonols, are widespread plant secondary metabolites important for adaptation to diverse abiotic biotic stresses. Flavonoids can be variously hydroxylated decorated; their biological activity is partly dependent on the degree of hydroxylation B-ring. Flavonoid biosynthesis regulated by MYB transcription factors, which have been identified characterized in a diversity plants. Here we characterize new activator, MYB117, hybrid poplar (Populus tremula×tremuloides). When overexpressed transgenic plants, MYB117 enhanced anthocyanin accumulation all tissues. Transcriptome analysis MYB117-overexpressing poplars confirmed up-regulation flavonoid genes, well two 3′,5′-hydroxylase (F3′5′H) genes. We also up-regulated cytochrome b5 required full F3′5′H . Phytochemical demonstrated corresponding increase B-ring flavonols these transgenics. Similarly, overexpression F3′5′H1 directly resulted increased hydroxylation, but without affecting overall content. However, gene F3′5′H1-overexpressing plants did not further hydroxylation. Our data indicate that regulates anthocyanins poplar, enhances up-regulating F3′5′H1.