RcMYBPA2 of Rosa chinensis functions in proanthocyanidin biosynthesis and enhances abiotic stress tolerance in transgenic tobacco

Proanthocyanidins (PAs) are major antioxidant flavonoids that play a key role in protecting plants against adverse environmental stress, but the transcriptional regulation of PAs synthesis in rose has not been fully investigated. Here, we report the functional characterization of RcMYBPA2 from rose (Rosa chinensis). RcMYBPA2 expression was induced by wounding, methyl viologen and salicylic acid. Overexpression of RcMYBPA2 in tobacco (Nicotiana tabacum) led to increased PAs concentrations, as well as enhanced tolerance to oxidative stress in comparison with the wild type (WT). Of special note, the transgenic plants exhibited lower levels of reactive oxygen species (ROS) than the WT, accompanied by higher levels of antioxidant enzyme activity under oxidative conditions. The ROS scavenging ability of the transgenic plants was compromised by inhibitors of antioxidant enzymes. In addition, a range of several stress-responsive genes was also up-regulated in the transgenic tobacco under oxidative stresses. Taken together, it is demonstrated that RcMYBPA2 is a positive regulator of the PAs biosynthetic pathway and participates in oxidative tolerance partly via modulating ROS scavenging ability and stress-responsive genes expression. Overexpression of RcMYBPA2 in tobacco led to increased PA content, as well as enhanced tolerance to oxidative stress via scavenging ROS and modulating expression of stress-responsive genes.