In vitro propagation for the conservation of a rare medicinal plant Justicia gendarussa Burm. f. by nodal explants and shoot regeneration from callus

Justicia gendarussa is a valuable medicinal plant and various parts of this plant are pharmaceutically used for the treatment of different diseases. In vitro regeneration of shoot buds was obtained from culture of nodal cuttings as well as shoot regeneration from callus. The nodal cuttings differed in shoot proliferation in terms of percentage of explants that responded and average shoot length with various concentrations (4.4, 8.9, 13.3, 17.7, 22.2 mu M) of 6-benzyladenine (BA), kinetin (Kn) and thidiazuron. In all treatments, one shoot was invariably present. Optimum 87% of cultures responded with an average shoot length of 4.4 cm on Murashige and Skoog (MS) medium supplemented with 17.7 mu M BA. Callus was induced from the mature leaf segments on MS medium supplemented with Kn (4.7, 13.9, 23.2 mu M) alone or in combination with 2, 4-dichlorophenoxyacetic acid (2, 4-D; 2.3 mu M, 4.5 mu M). Optimum callus induction (78%) was obtained on MS medium supplemented with 14 mu M Kn and 4.5 mu M 2, 4-D. When the callus was subcultured on MS medium fortified with BA (8.9, 17.7, 26.6 mu M) or Kn (9.3, 18.6, 27.9 mu M) alone or in combination with a naphthalene acetic acid (NAA; 2.7, 5.4 mu M), shoot regeneration was obtained. The highest response (92%) was observed on MS medium containing 17.7 mu M BA and 5.4 lM NAA. On this medium, an average number of 12.2 shoots were obtained per responding callus. The shoots obtained from callus and nodal cuttings were rooted with a frequency of 73% on MS medium augmented with 9.8 lM indole-3-butyric acid. The rooted shoots were successfully transplanted to soil and sand mixture (1: 1) with 90% survival rate. The protocol standardized for shoot proliferation and regeneration in J. gendarussa from nodal cuttings and leaf-derived callus is suitable for micropropagation and conservation of this essential medicinal plant.