Effect of seaweed elicitation and culture conditions on biomass and metabolite production in in vitro shoots of Withania somnifera
Sangeetha Vinod, Kanimozhi Natarajan, Krishnapriya Santhanu, Divya Selvakumar, Senthil Natesan, Kalaiselvi Senthil
Abstract
Withania somnifera is an important medicinal plant used in various herbal preparations due the presence of its key metabolites-withanolides. The present study focuses on the effect of seaweed extract and different in vitro culture conditions on the biomass and key metabolite content in in vitro shoot cultures of Withania somnifera. The commercially available seaweed extract powder of Kappaphycus alverizii with the trade name ’Magic vita - P’ was examined for its effect on solid, suspension and bioreactor cultures of Withania somnifera. The standardisation of elicitation conditions showed the exposure of shoot cultures to 0.25% seaweed extract for 7 days resulted in maximum biomass and withaferin A content which were 1.91 fold and 3.05 fold higher than that of untreated shoots. Further among the three culture conditions studied, the bioreactor cultures exhibited maximum growth index compared to the solid and suspension cultures thus producing maximum biomass which in turn resulted in higher accumulation of withanolides per batch of culture. Thus the seaweed treated shoots in bioreactor yielded 18.56, 8.96, and 7.29 fold increase in withaferin A, withanolide A and withanone content compared to control shoots in solid media. Further the effect of this elicitation and culture conditions on the accumulation pattern of the primary metabolites were studied using GC-MS. The Principal Component Analysis (PCA) of the GC-MS data exhibited a clear distinction between the control and seaweed treated samples. Thus our findings indicate a clear protocol for scaling up of withanolide production from in vitro shoot cultures of Withania somnifera.