Chrysanthemum officinale is a popular medicinal and edible plant that exerts its biological activities mainly through the presence of flavonoids and caffeoylquinic acids (CQAs). However, the regulatory mechanisms of flavonoid and CQA biosynthesis in chrysanthemum heads are unknown.
In this study, we determined the contents of flavonoids and CQAs during chrysanthemum capitulum development using high performance liquid chromatography (HPLC), and found that the contents were higher in the S1 and S2 stages, and gradually decreased in the S3 ~ S5 stages. Transcriptomic analysis showed that CmPAL1/2, CmCHS1/2, CmFNS, CmHQT and CmHCT were the key structural genes for flavonoids and CQAs biosynthesis. In addition, this study identified transcription factors (TFs) associated with flavonoids and CQA biosynthesis, including MYB, bHLH, AP2/ERF, and MADS-box families, by weighted gene co-expression correlation network analysis (WGCNA), k-means clustering, correlation analysis, and protein-interaction prediction.CmERF/PTI6 and CmCMD77 were considered to be upstream regulators of CmMYB3 and CmbHLH143, which in turn may form a complex that directly regulates the structural genes CmPAL1/2, CmCHS1/2, CmFNS, CmHQT, and CmHCT, thereby controlling flavonoid and CQA biosynthesis.
Overall, these findings initially revealed the TF regulatory network for the accumulation of flavonoids and CQAs in chrysanthemum heads, and laid a theoretical foundation for the quality enhancement of Hangbaichrysanthemum and the high-quality development of the industry.
