Enhancement of tanshinone production in Salvia miltiorrhiza Bunge (red or Chinese sage) hairy‐root culture by hyperosmotic stress and yeast elicitor

The present study evaluates the use of hyperosmotic stress and a biotic elicitor YE (yeast elicitor; polysaccharide fraction of yeast extract) to stimulate diterpenoid tanshinone production in hairy-root culture of Salvia miltiorrhiza Bunge (Lamiaceae). Sorbitol was applied as an osmoticum at various concentrations (30-100 g/l) to the hairy-root culture in MS (Murashige and Skoog) medium [Murashige and Skoog (1962) Physiol. Plant. 15, 473-497] containing 30 g/l sucrose, and it increased the TT (total tanshinone) content of roots most dramatically at 50-70 g/l (medium osmolality 410-500 mmol/kg; 1 mol/kg approximately 1 osmol/kg), to 4.5-fold of that in the control. The hairy roots showed strong tolerance to hyperosmotic stress, retaining a stable or higher dry weight of roots at osmolality up to 500 mmol/kg. Most remarkably, the combined use of sorbitol (50 g/l) and YE (100 mg/l) increased the TT content 10-fold (1481.6 versus 146.4 microg/g dry root) and the volumetric tanshinone yield 9-fold (16.3 versus 1.77 mg/l) compared with the control. The results suggest that the combined use of hyperosmotic stress and a biotic elicitor can effectively enhance secondary metabolite production in hairy-root cultures.