Comparative Transcriptome Profiling Reveals Two WRKY Transcription Factors Positively Regulating Polysaccharide Biosynthesis in Polygonatum cyrtonema .

() is a valuable rhizome-propagating traditional Chinese medical herb. Polysaccharides (PCPs) are the major bioactive constituents in . However, the molecular basis of PCP biosynthesis in remains unknown. In this study, we measured the PCP contents of 11 wild germplasms. The results showed that PCP content was the highest in Lishui Qingyuan (LSQY, 11.84%) and the lowest in Hangzhou Lin'an (HZLA, 7.18%). We next analyzed the transcriptome profiles of LSQY and HZLA. Through a qRT-PCR analysis of five differential expression genes from the PCP biosynthesis pathway, phosphomannomutase, UDP-glucose 4-epimerase (galE), and GDP-mannose 4,6-dehydratase were determined as the key enzymes. A protein of a key gene, , was localized in the chloroplast. The PCP content in the transiently overexpressed tobacco leaves was higher than in the wild type. Moreover, luciferase and Y1H assays indicated that PcWRKY31 and PcWRKY34 could activate by binding to its promoter. Our research uncovers the novel regulatory mechanism of PCP biosynthesis in and is critical to molecular-assisted breeding.