Influence of Hormones and Explants Towards In vitro Callusing and Shoot Organogenesis in a Commercially Important Medicinal Plant

The present study evaluates the effect of plant growth regulators (2, 4-D and Kinetin) and on two types of explants (leaf and node) on induction and growth of friable callus in Rauvolfia serpentina, a commercially important medicinal plant. Friable callus are the most suitable source for cell suspension culture that would enable the production of active principles at the in vitro level. For callusing, explants were obtained from shoots raised in vitro. Percentage response from nodal explant with respect to callus induction was comparatively higher (89.7 %) than that of leaf. While 2, 4-D (2 mg L -1 ) alone appeared to be effective but with Kinetin (1.6 mg L -1 ) proved to be the best PGR combination. Callus obtained were whitish to whitish green in color and friable in texture. Proliferation of callus significantly increased at 0.5 mg L -1 followed by 0.25 mg L -1 of 2, 4-D concentration alone. For shoot regeneration, calli were cultured in MS basal media supplemented with 2 mg L -1 BAP. Histological evaluation of paraffin sections of various stages starting from the callus initiation up to shoot regeneration were prepared, to study the developmental pattern of callus formation and shoot organogenesis in R. serpentina.