Transcriptomic, metabolomic, and proteomic analyses reveal UVB-stimulated biosynthesis of flavonoids, terpenoids, and alkaloids in dandelion (Taraxacum officinale)

Abstract

Ultraviolet-B (UVB) radiation acts as a natural environmental regulator that controls multiple physiological and metabolic processes in plants. Taraxacum officinale is a medicinal plant and dietary component that is notable for its abundance of bioactive secondary metabolites. To elucidate the response of secondary metabolites to UVB in T. officinale, we performed integrated transcriptomic, proteomic, and metabolomic analyses on leaf tissues following exposure to UVB for seven days. Transcriptomic analysis revealed a significant upregulation of genes associated with photosynthesis, flavonoid biosynthesis, and stress responses. Proteomic analysis identified upregulated proteins enriched in pathways related to secondary metabolite biosynthesis and alkaloid synthesis. Metabolomic profiling demonstrated a substantial increase in the accumulation of flavonoids, terpenoids, and alkaloids. Integrative network analysis further identified key transcription factors, including MYB, NAC, and bHLH, as central regulators of flavonoid, terpenoid, and alkaloid biosynthetic pathways in response to UVB exposure. Functional validation through transgenic overexpression in T. officinale demonstrated that ToMYB111, ToMYB113, and ToNAC068 act as positive regulators of flavonoid hyperaccumulation. Specifically, ToMYB113 and ToNAC068 transactivate the ToUGT1 promoter through direct binding, thereby enhancing flavonoid accumulation. These findings provide novel insights into the molecular basis of UVB-induced secondary metabolite accumulation in T. officinale, with potential applications in crop improvement and pharmaceutical development.