Liquid shoot culture of Salvia officinalis L. for micropropagation and production of antioxidant compounds; effect of triacontanol

Abstract

Liquid shoot culture of Salvia officinalis L. in MS medium containing IAA (0.1 mg l^-1) and BAP (0.45 mg l^-1) was developed and evaluated in relation to shoot multiplication and antioxidant compound (carnosic acid, carnosol and rosmarinic acid) accumulation. In the liquid medium, on average, 3 new shoots per explant (shoot tip) were obtained within 3 weeks. The shoots produced 8.2±0.02 mg of diterpenoids and 31.2±0.29 mg of rosmarinic acid per gram of dry weight. Shoot proliferation and diterpenoid content increased when triacontanol (5, 10 or 20 pg l^-1) was added to the liquid medium. In optimum conditions (at 20 pg l^-1 TRIA) almost 7 shoots were formed per explant after 3 weeks. An increase in diterpenoid production (expressed as the sum of carnosol and carnosic acid) ranged from 30% to 50% and dependended on triacontanol concentration tested. The level of diterpenoids in triacontanol-treated shoots was similar to the content of compounds in commercial herbal product (dried leaves of S. officinalis) (10-12 mg g^-1 dry wt). Triacontanol did not increase rosmarinic acid production, but the content of the phenolic as compound in shoots grown in liquid culture (31 mg g^-1 dry wt) was even 24 times higher compared to samples of dried leaves of S. officinalis plants. We also demonstrated that the highest amounts of CA, Car and RA were accumulated in young, top parts of sage shoots. This observation could be useful for improving the selection of material for the extraction of natural antioxidants from S. officinalis.