Chemical characterization and the intrusion through elicitation and Agrobacterium rhizogenes mediated hairy root transformation in Saussurea costus C.B. Clarke

Saussurea costus (Asteraceae) commonly known as kuth, is an important medicinal plant with a rich repository of medicinally valuable compounds. During the present study, pharmacologically important sesquiterpene lactones namely costunolide, dehydrocostus lactone, betulinic acid and syringin were isolated from different plant extracts. Furthermore, the elicitation effect of jasmonic acid (JA) and different light regiments on the accumulation of secondary metabolites (costunolide and dehydrocostus lactone) was evaluated using HPLC. There was an increase in amount of costunolide and dehydrocostus lactone compared to control after 96 h of treatment with JA and continuous light. The amount of costunolide after 96 h was maximum 6.47 mg/g DW in response to JA as compared to control which was found to be 1.7 mg/g DW. Similarly, the concentration of dehydrocostus lactone after 96 h showed maximum accumulation of compound 4.7 mg/g DW in response to continuous light. The in vitro response in MS medium augmented with BAP (4 mg/l) produces friable and creamish coloured callus, however, number of days increased from 10 to 22 days with 70% culture response. Also, Agrobacterium rhizogenes strain LBA9402 was found to be most effective strain for the establishment of hairy root cultures among all the strains used. The genomic DNA was used as template in PCR to amplify rolB gene which confirmed the efficient transformation of the roots. Additionally, total metabolite content of in vitro raised hairy roots of S. costus was significantly higher than the field grown plants. The production of secondary metabolites through elicitation and hairy roots can serve as a potential tool for the conservation action programme in S. costus.