Bolting reduces ferulic acid and flavonoid biosynthesis and induces root lignification in Angelica sinensis

Angelica sinensis is a perennial herbaceous species that produces the bioactive metabolites ferulic acid and alkylphthalides widely applied in the treatment of cardio-cerebrovascular diseases. While the effects of bolting on plant biomass and metabolites accumulation have been partly investigated, the mechanism of bolting reducing metabolites biosynthesis is still limited. In this study, the root biomass, accumulations of ferulic acid, flavonoids and lignin, antioxidant capacity, and related genes expression at four different bolting stages were investigated. The results showed that there was a 2.2-, 2.4- and 2.9-fold decrease of the root biomass, ferulic acid and flavonoids contents, while a 2.9-fold increase of lignin content on a per plant basis during the bolting stages. The antioxidant capacity also exhibited significant decrease with growth and development. The differential expression levels of the 20 genes, which are involved in biosynthesis of ferulic acid (e.g. AsPAL1, As4CLs and AsHCT), flavonoids (e.g. AsCHS, AsCHI and AsI3'H) and lignin (e.g. AsCAD1 and AsLACs), were consistent with changes in the above metabolites accumulation. The findings will provide useful references for improving the production of bioactive metabolites in A. sinensis.