Regenerative callus induction and biochemical analysis of Stevia rebaudiana Bertoni

Stevia Leaves are the principal source of stevioside, which is estimated to be 100-300 times sweeter than table sugar. Stevioside has clinical significance as they are reported to maintain glucose levels in human blood. Owing to the difficulties in propagation of stevia through seeds and vegetative methods, callus culture has been an efficient alternative for generation of stevioside. The aim of this study is to develop an efficient and standardized protocol for maximum induction and multiplication of callus from a leaf. Callus culture was established from leaves in MS basal media fortified with various combinations (BAP, NAA, 2,4-D, KN, IBA) and concentrations of phytohormones. The best callusing (100%) was recorded in MS media supplemented with (2,4-D 1.0mg/l + NAA 1.0mg/l). The callus was harvested after 4 weeks and screened for the presence of various bioactive compounds. The qualitative results showed that the extracts of callus contained bioactive compounds like flavonoids, glycosides, phenol, tannins, sterols and saponins thereby making callus one of the sources for extraction of various secondary metabolites.