Primary and secondary metabolites produced in Salvia miltiorrhiza hairy roots by an endophytic fungal elicitor from Mucor fragilis

Salvia miltiorrhiza is one of the most commonly used medicinal materials in China. In recent years, the quality of S. miltiorrhiza has attracted much attention. Biotic and abiotic elicitors are widely used in cultivation to improve the quality of medicinal plants. We isolated an endophytic fungus, Mucor fragilis, from S. miltiorrhiza. We compared the effects of endophytic fungal elicitors with those of yeast extract together with silver ion, widely used together as effective elicitors, on S. miltiorrhiza hairy roots. Seventeen primary metabolites (amino acids and fatty acids) and five secondary metabolites (diterpenoids and phenolic acids) were analyzed after elicitor treatment. The mycelium extract promoted the accumulation of salvianolic acid B, rosmarinic acid, stearic acid, and oleic acid in S. miltiorrhiza hairy roots. Additionally, qPCR revealed that elicitors affect the accumulation of primary and secondary metabolites by regulating the expression of key genes (SmAACT, SmGGPPS, and SmPAL). This is the first detection of both the primary and secondary metabolites of S. miltiorrhiza hairy roots, and the results of this work should help guide the quality control of S. miltiorrhiza. In addition, the findings confirm that Mucor fragilis functions as an effective endophytic fungal elicitor with excellent application prospect for cultivation of medicinal plants.