Dual Elicitation for Improved Production of Withaferin A by Cell Suspension Cultures of Withania somnifera

High yielding transformed callus culture of W. somnifera was established by infecting hypocotyls with Agrobacterium tumefaciens MTCC-2250. Maximum withaferin A content of 0.0875 mg/g dry cell weight and transformation efficiency of 80% were obtained. Confirmation of transformation was done on the basis of the presence of the ags gene by using polymerase chain reaction. Various abiotic elicitors (arachidonic acid, methyl jasmonate, calcium chloride, and copper sulfate) and biotic elicitors (cell extracts and culture filtrates of Alternia alternata, Fusarium solani, and Verticilium dahaliae) were tested at different concentrations to enhance withaferin A production in suspension culture of transformed cells. Maximum enhancements of 5.4 times and 9.7 times, respectively, were obtained when copper sulfate (100 mu M) and the cell extract of V. dahaliae (5% v/v) were added separately to suspension cultures. The dual elicitation strategy by the combined addition of these two elicitors resulted in 13.8-fold enhancement of withaferin A content in comparison to control cultures (2.65 mg/L). The present study indicates the potential of this biotechnology-based methodology for the large-scale production of withaferin A.