IN VITRO CALLOGENESIS AND ORGANOGENESIS IN DIFFERENT EXPLANTS OF STEVIA (STEVIA REBAUDIANA)

Abstract

Different explants of Stevia rebaudiana i.e. leaf, node and shoot apices were used to callus initiation and regeneration of shoots when cultured on Murashige and Skoog (MS) medium supplemented with different concentration of auxins and cytokinins. Different concentrations of 2, 4-D were used for callus initiation in leaf and nodal explants. In the case of leaf explants the best callus was observed at the concentration of 2.5 mg/l 2, 4-D (2, 4 Dichloro phenoxyacetic acid) and in nodal explants at the concentration of 1.5 mg/l 2, 4-D. Leaf calluses were subcultured in different concentrations of 2,4-D as well as BAP (Benzyl amino purine) +IAA( Indole-3- acetic acid )for further proliferation of callus and for organ formation. The combination of BAP+IAA (2+1 mg/l) was considered the best medium for organ formation. For shoot apices, different concentrations of BAP alone and in combination with IAA were tested, BAP (1mg/l) alone or BAP+IAA (2+1mg/l) gave the best response. Regenerated shoots were transferred to the rooting medium containing different levels of auxins. Medium containing 0.5 mg/l IBA (Indole-3- butyric acid) favored root formation.