Yeast extract improved biosynthesis of astragalosides in hairy root cultures ofAstragalus membranaceus

The dried root ofAstragalus membranaceusis a well-known herbal medicine, and it is useful in treating chronic diseases and weakness, as well as for improving overall health and vitality. Astragalosides, which are root quality indicators ofA. membranaceus, are natural triterpenoid saponins that are used in the treatment of diabetes and cardiovascular diseases. Currently, there is an urgent need to improve their production because of their low quantity in plants and the difficulty of chemical synthesis. In this study, yeast extract was added to facilitate elicitation inAgrobacterium-mediated hairy root cultures, thereby enhancing astragaloside production inA. membranaceus. Results showed that yeast extract could stimulate astragaloside content effectively in the hairy roots ofA. membranaceus. Moreover, astragaloside accumulation was positively correlated with the upregulation of mevalonate biosynthetic gene expression in the presence of yeast extract. Our study demonstrated that pretreatment with yeast extract (3.65 mM) for 72 h serves as an effective strategy to enhance astragaloside levels inA. membranaceushairy root cultures. Thus, these optimal conditions can provide valuable information for the improvement of astragaloside industrial production inA. membranaceus.