TDZ Plays Key Role in Shoot Regeneration from Different Explants of Picrorhiza kurroa: An Endangered Medicinal Herb of Western Himalayas

Picrorhiza kurroa plants were collected from its natural habitat. In vitro plants were raised from the leaves of high yielding collection screened in an earlier study. Leaves, roots and internodal segments were cultured for 15 days. The effect of thidiazuron (1-phenyl-3-(1, 2, 3- thiadiazol-5-yl) urea; TDZ) pretreatment for 15 days on regeneration potential of different explants viz. leaves, roots and internodes of Picrorhiza kurroa was studied. Regeneration potential varied significantly with the type of explant. Regeneration response of 100% with 46.25 shoots per explant was obtained in leaf segments of 2.0 cm length pretreated with 0.5 µM TDZ for 15 days and then transferred to 2.32 µM kinetin (Kn) containing MS basal medium. In case of root explants maximum shoot number (17.12) was obtained on 0.5 µM TDZ pretreated for 15 days and then to 3.64 µM Kn. Maximum shoots per explants (12.33) were obtained in case of internodes pretreated with 0.5 µM TDZ for 15 days and transferred to 1.16 µM Kn. Regenerated shoots from different explants developed in vitro rooting on MS basal medium within 7-8 days. Conclusively, an efficient and repeatable protocol for rapid regeneration from different explants and in vitro rooting has been developed in P. kurroa which can be effectively used for its conservation.