Betalain estimation and callus induction in different explants of Bougainvillea spp.

The present study was carried out to investigate the in vivo betalain content in bract and leaf of some bougainvillea cultivars and to develop a reliable, rapid and efficient callus induction protocol. The maximum betacyanin content in bracts was recorded in the cv. Bhabha (2.68 mg/g FW) followed by cv. Rao (2.40 mg/g FW). The maximum betaxanthin content in bracts was recorded in the cv. Lady Mary Baring (1.27 mg/g FW). The maximum betacyanin content in leaf was recorded in the cv. Dr H B Singh (0.58 mg/g FW), while the maximum betaxanthin content in leaf was recorded in the cv. Bhabha (0.73 mg/g FW). The total betalain content in bract was estimated to be maximum in the cv. Bhabha (3.60 mg/g FW) followed by cv. Rao (3.36 mg/g FW). The total betalain content in leaf was highest in cv. Bhabha followed by cv. Dr R R Pal. Of the different treatments employed for callus induction on Murashige and Skoog’s (MS) medium using leaf explants in bougainvillea cv. Bhabha, the treatment comprising 6 mg/l 2,4-D recorded maximum induction coefficient (98.75%) and minimum days (8.50) was required for callus initiation. In case of internodal explants the induction coefficient was lower and more number of days was required for callus initiation. No callus induction was recorded on bract. Absolutely no callus induction was noted on the MS basal medium devoid of plant hormones (control). The maximum gain in callus biomass accumulation, in both the explants, in terms of fresh and dry cell weight was recorded in the callus cultured on MS medium supplemented with 6 mg/l 2,4-D. This treatment also resulted in lowest fresh and dry cell weight ratio in leaf and internodal explants. Wounding of leaf explants was found to be beneficial for accelerating the callogenesis process. The multiplication of callus was satisfactory on MS medium supplemented with doubled quantity of vitamins and 6 mg/l 2,4-D.