Transcriptomic and Metabolomic Analyses Provide Insights Into the Flavonoid Biosynthesis in Dangshen.

Introduction: Dangshen (DS) has been used for hundreds of years as a traditional Chinese medicine. It has a wide range of biological activities. Flavonoids are one of the important bioactive components with strong free radical scavenging and antioxidant capacity in DS. However, the biosynthesis process of flavonoids in DS remains unclear.

Objective: The aim of this study was to understand the biosynthesis molecular mechanism of flavonoids in DS.

Methods: In this study, metabolomics research and transcriptome sequencing for DS were carried out. Transcript and metabolite profiles were generated by high-throughput RNA sequencing (RNA-seq) data analysis and liquid chromatography-tandem mass spectrometry, respectively.

Results: In total, 256 metabolites were identified in the root, stem, leaf, and flower of DS using untargeted metabolomics. Among them, 55 flavonoids, including pinobanksin, butein, fustin, pelargonidin, apigenin, luteolin, and eriodictyol, were closely related to flavonoid metabolism, and most of them were upregulated in different tissues of DS. Furthermore, the differentially expressed genes identified by transcriptomics were mainly enriched in the biosynthesis of flavonoid, isoflavonoid, flavone, and flavonol. A number of genes, including ANS, CCOAOMT, CHI, CHS, CYP75B1, CYP75A, CYP93B2_16, CYP98A/C3'H, DFR, F3H, FLS, and HCT, may regulate the production of flavonoids in different tissues of DS. An integrated analysis of transcriptome and metabolome revealed the flavonoid biosynthetic network in DS and elucidated the diversity of flavonoid biosynthetic pathway in roots, stems, leaves, and flowers of DS.

Conclusion: Our findings provide a molecular basis and new insights into flavonoid biosynthesis in DS and lay the foundation for breeding new valuable DS cultivars.