Abstract
An efficient system for in vitro propagation of the endangered medicinal plant Rauvolfia serpentina has been developed. Proliferation of shoots was achieved from nodal segment explants, excised from a field grown plants on Murashige and Skoog (MS) medium supplemented with thidiazuron (TDZ) (0.1-2.5 μmol/L) although with low regeneration response and few number of shoots per explant. Greater number of shoots was achieved from nodal explants pretreated with higher concentrations of TDZ (5-100 μmol/L) in liquid MS medium for different time periods (4, 8, 12 and 16 days), followed by their transfer on a growth regulator-free medium. The highest response in terms of percent regeneration (90%), average number of shoots/explant (23.17 ± 2.15) and maximum shoot length (5.3 cm ± 0.83 cm) were achieved by pretreating the nodal explants with 50 μmol/L TDZ for 8 days. Rooting was achieved in MS medium supplemented with 0.5 μmol/L indole-3-butyric acid with an average of 5.50 ± 0.92 roots per microshoot. The rooted plantlets were transferred to soil, where 90% of them grew well and exhibited a normal development. Chlorophyll a and b, carotenoids, net photosynthetic rate and antioxidative enzymes, viz., superoxide dismutase and catalase activities were measured in leaf tissues during ex vitro acclimatization at 0, 7, 14, 21 and 28 days. Most of the activities showed a decreasing trend but subsequently increased after 7 days of acclimatization. These changes suggested the adjustment of the in vitro propagated plantlets to ex vitro conditions.