Regeneration of plants from alginate-encapsulated shoots of Tylophora indica (Burm. f.) Merrill, an endangered medicinal plant

A protocol has been developed for plant regeneration from encapsulated nodal segments of Tylophora indica. Nodal segments collected from a 2-year-old plant were encapsulated in calcium alginate beads. The best gel complex was achieved using 3% (w/v) sodium alginate and 100 mM CaCl2.2H(2)O. The maximum frequency (91%) of conversion of encapsulated beads into plantlets was achieved on Murashige and Skoog (MS) medium containing 2.5 mu M 6-benzyladenine (BA) and 0.5 mu M alpha-naphthalene acetic acid (NAA) after 6 weeks of culture. Encapsulated nodal segments stored at 4 degrees C for 1 - 8 weeks also showed successful conversion, followed by development into complete plantlets when returned to regeneration medium. Conversion of encapsulated nodal segment into plantlets also occurred when the calcium alginate beads were sown directly into Soilrite (TM) moistened with 1/2MS salts. Plants regenerated from encapsulated nodal segments could be hardened, acclimatised and established in soil, with a success rate of 90%. Encapsulation of vegetative propagules in calcium alginate beads could be useful for the exchange, storage and micropropagation of germplasm of this endangered medicinal plant.