Tanshinone production and isoprenoid pathways in Salvia miltiorrhiza hairy roots induced by Ag⁺and yeast elicitor

This work examined the accumulation of diterpenoid tanshinones and related secondary metabolism pathways in hairy root cultures of Salvia miltiorrhiza Bunge (Lamiacae) induced by a biotic elicitor, the carbohydrate fraction of yeast extract (YE, 100 μg mL-1), and an abiotic elicitor, Ag+(30 μM). The activity of 3-hydroxy-3-methylglutaryl CoA redutase (HMGR) was only stimulated by Ag+, and 1-deoxy-d-xylulose 5-phosphate synthase (DXS) was stimulated by both, but more strongly by YE. While the non-MVA pathway inhibitor fosmidomycin inhibited the tanshinone accumulation induced by both elicitors, the MVA-pathway inhibitor mevinolin only suppressed the Ag-induced tanshinone accumulation. The results suggest that the tanshinone accumulation induced by the two elicitors was mainly synthesized via the non-MVA pathway (DXS activity), but could depend on crosstalk between the MVA and non-MVA pathways. Furthermore, the pretreatment of hairy roots with Ag+for 24-48 h potentiated the YE-induced tanshinone production and DXS activity.