Metabolomic and Transcriptomic Analyses Reveal Changes in Active Components During the Growth and Development of Comfrey (<i>Symphytum officinale</i> L.)

Comfrey (<i>Symphytum officinale</i> L.) is a traditional medicinal plant, and its growth period has an important effect on the accumulation of active components. Phenolic acids and flavonoids are the most important active components in comfrey, but their accumulation in comfrey has not been studied. At present, most research on comfrey focuses on its roots. There is still a lack of systematic research on the comparison of active components and biological activities in the aerial parts of comfrey in different growth periods. To explore the influence of the growth period on the active components of comfrey, non-targeted metabolomics and transcriptomics were used to comprehensively analyze the active components of comfrey during the vegetative period, blooming period, and maturity period and compare the dynamic changes in phenolic acid and flavonoid accumulation during different growth periods of comfrey. The results revealed that the vegetative period presented the highest total phenol and flavonoid contents. The predominant secondary metabolites associated with phenolic acids and flavonoids were integral to the phenylpropanoid, flavonoid, and isoflavonoid biosynthetic pathways. Critical structural genes governing these metabolic processes—PAL, C4H, 4CL, CHS, FLS, and DFR—exhibited marked upregulation during the vegetative growth stage. Comprehensive transcriptomic analysis and weighted gene co-expression network analysis were used to construct a co-expression network of structural genes and transcription factors that affected the accumulation of specific metabolites, and the transcription factors related to the synthesis of flavonoids and phenols were predicted. These findings elucidate the temporal regulatory mechanisms governing the growth-phase-dependent accumulation of bioactive constituents in comfrey, advancing the understanding of phytochemical dynamics in medicinal plants.