Micropropagation, in vitro flowering, and tuberization in Brachystelma glabrum Hook. f., an endemic species

Brachystelma glabrum Hook. f. is an endemic plant species of Eastern Ghats, India. In this study, efficient protocols for in vitro micropropagation, flowering, and tuberization of this plant were developed. Sterilized shoot tip and nodal explants were cultured on Murashige and Skoog (MS) medium supplemented with different plant growth regulators (PGRs) and additives for shoot induction and multiplication. Both shoot tip and nodal explants showed the best response (90 and 100%, respectively) on MS medium supplemented with thidiazuron (TDZ) at 1.0 mg L-1. The microshoots multiplied best on MS + TDZ (1.0 mg L-1) in combination with alpha-naphthaleneacetic acid (NAA) at 0.5 mg L-1 and coconut water (CW) at 25%. The highest number of in vitro flowers (4.0 flowers per microshoot) was observed on MS medium supplemented with a combination of N6-benzyladenine (BA) and indole-3-butyric acid (IBA), each at 1.5 mg L-1. In vitro-derived shoots produced aerial tubers on MS + TDZ (2.0 mg L-1) + IBA (0.5 mg L-1) and basal tubers on MS + TDZ at 2.0 mg L-1. In vitro shoots were best rooted on half-strength (1/2) MS + NAA at 0.5 mg L-1. The rooted plantlets were successfully acclimatized inpots with70% survival after a hardening period of 1 mo. This protocol provides an effective method for the conservation of this endemic plant species.