Direct and indirect method of plant regeneration from root explants of Caesalpinia bonduc (L.) Roxb.--a threatened medicinal plant of Western Ghats.

An in vitro regeneration protocol has been standardized via direct and indirect methods from excised root explants of C. bonduc, a threatened woody legume used for the treatment of contagious diseases, inflammation, leprosy, antiperiodic, febrifuge, anthelmenthic, urinary disorders, leucorrhoea, piles and to heal wounds. MS medium supplemented with 17.75 micromol BAP and 2.46 micromol IBA, induced a mean of 3.40 +/- 1.07 shoots directly from the surface of excised root explant. Subsequently, the shoots rooted readily on MS half strength medium with out growth regulators. In indirect organogenesis, callogenic frequency was optimized (96.66%) at the concentration of 9.04 micromol 2, 4-D and 0.88 micromol BAP. An average, 15.30 +/- 5.25 shoots were differentiated from the root callus at the concentration of 17.57 micromol BAP and 2.85 micromol IAA. Shoots regenerated through callus were rooted well on MS half strength medium with growth regulators at 2.95 micromol IBA. Rooted plantlets were transferred to the pots containing sterilized soil and were successfully hardened at greenhouse condition for three weeks then exposed to the natural environment. Survival rate was more (95%) in plantlets derived through direct organogenesis than (60%) the plantlets regenerated through root calli.