Development of an elicitation strategy on enhanced accumulation of oleanolic acid in suspension cultures of Ocimum tenuiflorum L.

Ocimum tenuiflorum Linn. is an important aromatic medicinal plant which produces several secondary metabolites responsible for diverse pharmacological activities. The present study focuses on enhanced production of biomass as well as oleanolic acid (OA), an anticancer and antioxidant compound, in suspension cell cultures of O. tenuiflorum upon elicitation with different elicitors. Leaf explants derived friable calli were inoculated intol iquid Murashige and Skoog (MS) media containing plant growth regulators [0.25 mg/L of α-naphthaleneacetic acid (NAA) and 0.5 mg/L of 6-benzyl amino purine (BAP)] for the establishment of suspension cultures. Influence of several factors such as, age of the suspension cultures, different concentrations, and exposure times of various elicitors such as yeast extract (YE), methyl jasmonate (MeJ) and salicylic acid (SA) respectively were analysed for cell biomass production and accumulation of OA during this study. Among the elicitors tested, YE at 50 mg/L was found to be the most efficient in terms of increased biomass production and accumulation of OA in the cultures. The highest increase in OA production (13.16-fold in elicited cultures compared to untreated cultures) was noted on 17-day-old suspension cultures when exposed to 50 mg/L of YE for four days. Enhancement of 2.72-fold in OA content was also recorded in 17-day-old cultures when treated with MeJ (60 mg/L) during two days of exposure. SA was not efficient in inducing accumulation of OA in 17- and 22-day-old suspension cultures at any concentration and exposure time. Furthermore, it was observed that the effect of different elicitors on biomass production and OA content depended on concentration and the duration of exposure times. Therefore, utilization of elicitation method could be a promising tool to enhance cell growth and OA accumulation in the suspension cell cultures of O. tenuiflorum.