Optimization of Elicitation Conditions with Methyl Jasmonate and Salicylic Acid to Improve the Productivity of Withanolides in the Adventitious Root Culture of Withania somnifera (L.) Dunal

Adventitious root cultures derived from leaf derived callus of Withania somnifera (L.) Dunal were treated with methyl jasmonate and salicylic acid independently. Biomass accumulation, culture age, elicitation period, and culture duration were optimized for higher withanolides production in the two best-responding varieties collected from Kolli hills (Eastern Ghats) and Cumbum (Western Ghats) of Tamil Nadu, India. Between the two elicitors, salicylic acid (SA) improved the production of major withanolides (withanolide A, withanolide B, withaferin A, and withanone) as well as minor constituents (12-deoxy withastramonolide, withanoside V, and withanoside IV) in the Kolli hills variety. Treatment of root biomass (11.70 g FW) on 30-day-old adventitious root cultures with 150 μM SA for 4 h elicitor exposure period resulted in the production of 64.65 mg g−l dry weight (DW) withanolide A (48-fold), 33.74 mg g−l DW withanolide B (29-fold), 17.47 mg g−l DW withaferin A (20-fold), 42.88 mg g−l DW withanone (37-fold), 5.34 mg g−l DW 12-deoxy withastramonolide (nine fold), 7.23 mg g−l DW withanoside V (seven fold), and 9.45 mg g−l DW withanoside IV (nine fold) after 10 days of elicitation (40th day of culture) when compared to untreated cultures. This is the first report on the use of elicitation strategy on the significant improvement in withanolides production in the adventitious root cultures of W. somnifera.