Callogenesis of Sida rhombifolia L.: A Threatened Medicinal Plant

Protocol for callogenesis of a species belonging to the genus Sida (Malvaceae) has been standardized. Sida rhombifoliaL. var. rhomboidea (Roxb.) Mast., the 'swetberela', is an important medicinal plant used in Rural Bengal. The plant is presently not found in wild state, though grown in the gardens of the herbalists. In order to formulate the micropropagation strategies of this threatened plant, its various parts were used as explants for callogenesis. Among the explants, callus initiation was noticed with shoot tip and young leaf explants when cultured on MS medium supplemented with 3% sucrose and 1 mg/l each of NAA and IAA. For appreciable growth of the callus coconut milk (25% v/v) was required to be added to the initiation medium. With respect to callus growth, shoot tip was found to be better explant than young leaves. The callus failed to produce somatic embryogenesis. However, rhizogenesis was induced by sub-culturing the calli in the initiation medium. Different hormonal combinations often caused the transformation of the calli from the whitish, translucent, soft and friable nature to compact and yellowish or brownish forms.