Influence of biotic and abiotic elicitors on production of betalain pigments in bougainvillea callus cultures

The present study was carried out to investigate the effects of various biotic and abiotic elicitors on biosynthesis of betalain pigments in bougainvillea callus cultures. Addition of different concentrations of biotic elicitors (methyl jasmonate [MJ] and β-glucan) and abiotic elicitors (calcium chloride, FeEDTA and copper sulphate) into basal Murashige and Skoog's (MS) medium influenced betacyanin and betaxanthin production. Treatment with 0.5 μM MJ was found to be most effective in inducing betalain biosynthesis in the callus. Maximum response coefficient (81.25%), earliest pigment initiation (7 days) and intensification (13.75 days) was observed with 0.5 μM MJ. Beyond this concentration there was a decrease in response coefficient and pigment content. Among the different concentrations of β-glucan, 0.5 mg/l was most effective in increasing the betacyanin and betaxanthin contents (0.35 and 0.22 mg/g FW respectively). Among the abiotic elicitors, calcium chloride at 5 g/l showed maximium response coefficient (78.75%), betacyanin (0.61 mg/g FW) and betaxanthin content (0.42 mg/g FW). FeEDTA at 100 μM and CuSO₄ at 20 μM showed good response coefficient with higher betaxanthin and betacyanin content but at higher concentrations both the response coefficient and pigment production decreased. Correlation between response coefficient, betacyanin and betaxanthin content was also calculated.