EN
Leaf regeneration via direct induction of adventitious shoots obtained from an endangered medicinal plant, Curculigo orchioides Gaertn. by pretreating with thidiazuron. C. orchioides is an endangered medicinal herb belonging to the family Hypoxidaceae. Direct inoculation of leaf pieces on MS medium supplemented with various concentrations of BAP (2–8 µM) or TDZ (2–8 µM) alone or in combination with NAA (0.5 and 1.0 µM) produced low shoot induction both in terms of % response and number of shoots per explant. Hence, leaf explants were pretreated with 15, 25 or 50 µM thidiazuron (TDZ), for 6, 24 or 48 h with the aim of improving shoot regeneration from cultured explants. After pretreatment, explants were transferred to an agar solidified MS medium that was supplemented with BAP (4 µM), TDZ (6 µM), BAP (4 µM) + NAA (1.0 µM), TDZ (6 µM) + NAA (0.5 µM). Control explants were incubated directly on the medium without any pretreatment. The pretreatment of explants with 15 µM TDZ for 24 h significantly promoted the formation of adventitious shoots and the maximum response was observed on MS medium supplemented with 6 µM TDZ. In this medium, 96 % cultures responded with an average number of 16.2 adventitious shoots per explant. The percentage of leaf explants producing shoots and the average number of shoots per explant were significantly improved when TDZ pretreated leaves were cultured onto MS medium supplemented with BAP or TDZ alone or in combination with NAA. The rooted plantlets were successfully transplanted to soil with 90% success. The present investigation indicated the stimulatory role of TDZ pretreatment in regulating shoot regeneration from leaf explants of C. orchioides.