Identification and characterization of 5 MYB transcription factors regulating the polydatin biosynthesis in Polygonum cuspidatum Sieb. et Zucc

Polydatin, a glucoside of resveratrol, has improved bioavailability and higher anti-inflammatory, antioxidant, and anti-apoptotic activities. Currently, the regulatory mechanism of polydatin biosynthesis remains largely unknown. We previously identified a glycosyltransferase PcUGT95D10 which could catalyze the formation of polydatin from Polygonum cuspidatum Sieb. et Zucc., a main source of polydatin in industrial scale. This study is to further investigate its catalytic mechanism and transcriptional regulatory mechanism for resveratrol. PcUGT95D10 exhibited sugar donor promiscuity, and the residues around active pocket, especially the Gly161, played key roles in the glycosylation. By comparative analysis of transcriptome and metabolome, along with Y1H assay, 5 MYB transcription factors (PcMYB1, PcMYB10, PcMYBR01, PcMYB114, and PcMYB306) linked to PcUGT95D10 expression were characterized. The identical or opposite expression patterns of the 5 PcMYBs in different tissues with PcUGT95D10 gene and polydatin content revealed their regulatory effects on the polydatin biosynthesis. PcMYB1, PcMYB10, PcMYBR01, PcMYB114, and PcMYB306 all could specifically bind to the AC-box element in PcUGT95D10 promoter, with PcMYB1, PcMYB10, and PcMYBR01 as activators to enhance the promoter activity, while PcMYB114 and PcMYB306 playing the inhibiting role. In addition, overexpressing PcMYB1 , PcMYB10 , or PcMYBR01 increased the polydatin accumulation in P. cuspidatum , while the polydatin content was reduced in transgenic PcMYB114 -overexpressed and PcMYB306 -overexpressed hairy roots. In sum, this study successfully identified the potential key residues of PcUGT95D10 glycosylating resveratrol and elucidated a regulatory network of MYB transcription factors for polydatin biosynthesis in P. cuspidatum , which offers new insights into the molecular mechanism of polydatin biosynthesis in P. cuspidatum. • PcUGT95D10 exhibits sugar donor promiscuity for diverse substrate aglycones. • The residue Gly161 in PcUGT95D10 is vital for the glycosylation of resveratrol. • PcMYB1, PcMYB10, and PcMYBR01 serve as activators in the polydatin biosynthesis. • PcMYB114 and PcMYB306 negatively regulate the polydatin production.