In vitro production of tanshinones in adventitious root cultures of Perovskia abrotanoides Kar. under Ag+ ion and yeast extract elicitation

Perovskia abrotanoides Kar. is a perennial species, which belongs to Lamiaceae family. Some pharmaceutical properties (antimicrobial, anti-diabetes, anti-inflammatory and anti-cancer activities) attributed to this plant roots are related to the presence of diterpenoid tanshinones. This study was aimed to investigate the effect of single and combination treatments of AgNO3 (Ag+) and yeast extract (YE) on growth and tanshinone production in adventitious root cultures of P. abrotanoides. Leaf explants were induced to form adventitious roots on a solid MS medium containing 2 mg/L NAA. Regenerated roots were subsequently transferred to a liquid MS medium, for multiplication. In the first experiment, adventitious roots were treated with 25 μM Ag+ for 24, 48 and 168 hours (one week), and the one-week treatment was chosen as the best condition to promote root growth and tanshinone production. In combination treatments, 12, 24 and 48 hours after Ag+ pre-treatment, 200 mg/L YE was added to the cultures, and roots were harvested one week after the first elicitation. Single treatments improved root growth and tanshinone production (six-fold increase compared with the control). Maximum amount of tanshinone-IIA (12 times higher than control) was obtained after a one-week treatment with Ag+. Under the combination treatments, amount of different tanshinones varied depending the time period of YE elicitation. In the best case, two-fold increase in total tanshinone content (over the single treatments) was found 12 hours after addition of YE to Ag+-pre-treated cultures, which was due to the remarkable increase in tanshinone-I. No significant changes were measured in cryptotanshinone levels.