In vitro studies on the bearing ability of Stevia for stevioside biosynthesis

In this experiment, one month old callus tissues derived from leaf explants of Stevia cultured on half MS medium with 3 per cent sucrose supplemented with 2, 4-D alone and in combination with BA, BAP and Kinetin separately at different concentration levels was analysed by RP-HPLC to ascertain whether the plant growth regulator on which the callus tissues cultured had a bearing on the biosynthesis of steviosides. The leaf explants were also evaluated for parameters such as days taken for initiation of callus and that to become necrotic, type of callus and its biomass. A friable good yellow coloured callus was obtained in all the treatments contained 2, 4-D itself. However, the intensity of yellow colour was reduced with the addition of BA and kinetin whereas; the glossiness was improved in presence of BAP. Medium having 2 mg/l 2, 4-D and 0.2 mg/l BAP produced callus early (29 days) and was maintained for more than two and half month without any necrotic symptoms. The fresh weight of the callus was increased with the increase in the concentration of 2, 4-D. With the addition of cytokinins the biomass accumulation was reduced but improved with the increase in their concentration. The callus cultured on MS medium containing 2, 4-D (2 mg/l) and BA (0.2 mg/l) has produced higher biomass (1.40 g F.W. and 0.206 g D.W.) and stevioside synthesis (10.80%).