Effect of growth regulators on rapid micropropagation and psoralen production in Psoralea corylifolia L.

A rapid and efficient micropropagation system was developed for Psoralea corylifolia, an endangered, valuable medicinal plant. Multiple shoot buds were obtained in half-strength liquid Phillips-Collins (L2) medium supplemented with 5 mu M benzylaminopurine (BA) and 5 mu M thidiazuron (TDZ) from apical bud explants of 1-week-old cultures. The shoot buds were subcultured on enriched solid L2 medium supplemented with different concentrations and combinations of BA, kinetin (KIN), 2-isopentenyladenine (2iP), TDZ, bavistin (BVN) and trimethoprim (TMP). Enriched solid L2 medium supplemented with 2 mu M BA, 1 mu M TDZ and 100 mg l(-1) BVN were more effective in producing greater number of shoots per explant (85.2 +/- 0.9 shoots/explant) after 4 weeks of culture. The regenerated shoots (40-50 mm in length) rooted and accompanied by hardening upon transfer to 50 mu M indole-3-butyric acid (IBA) for 15 min and followed by planting in sterile soil mixture and vermiculate (3:1 v/v), with 50 ml of one-eight strength L2 basal salt solution devoid of sucrose and inositol, supplemented with 5 mu M IBA and 100 mg l(-1) BVN. The plants achieved 100% rooting with hardening. Subsequently the rooted plants were successfully established in the field. The survival percentage differed with seasonal variations. The concentration of psoralen was evaluated in different tissues of ex vitro and in vivo grown plants by high-performance liquid chromatography (HPLC). Psoralen content was increased in leaves (2.97%), roots (2.38%), stems (5.40%) and seeds (1.63%) of ex vitro plants than the in vivo plants. This system facilitates for commercial and rapid propagation of P. corylifolia for conservation strategies and phytomedicine production.