R2R3-MYB transcription factor PbMYB5-like positively regulates the biosynthesis of phenylalanine-related metabolites in pear (Pyrus bretschneideri)

The red color of red pears is primarily attributed to the accumulation of anthocyanins, which are biosynthesized via the phenylalanine pathway. However, research into the regulation of these processes is currently limited. The study found that increasing the expression of the transcription factor PbMYB5-like resulted in increased expression of genes involved in anthocyanin, proanthocyanidin (PAs), and lignin biosynthesis, as well as anthocyanin accumulation in pear epidermis. The experiments demonstrated that PbMYB5-like interacts with bHLH3, resulting in the formation of the PbMYB5 like-bHLH3-WD40 complex, which regulates the expression of structural genes such as CCR, F5H, LAR, ANS, UFGT, and others. Furthermore, PbMYB5-like has been demonstrated to directly bind to the promoters of CHI, F3H, ANS, and UFGT genes, thereby regulating the synthesis of related metabolites. The findings of this study provide a foundation for understanding the mechanisms by which PbMYB5-like regulates pear skin color, which is a pivotal aspect in pear breeding and germplasm innovation.