In vitro morphogenetic responses from cotyledonary explants of immature zygotic embryos of Pterocarpus santalinus

Pterocarpus santalinus is an endangered species with high therapeutic and commercial value that needs urgent protection. The study developed an easy and notable protocol for in-vitro regeneration via callus formation of the species using cotyledons from germinated immature zygotic embryos. The efect of plant growth regulators on callogenesis and morphogenesis was studied. Our investigation demonstrated that maximum callus mass (1036.44 mg) was obtained when Murashige and Skoog (MS) medium were supplemented with 0.1 mg/l BAP and 8 mg/l NAA. However, maximum callus frequency (95.37%) was obtained with 0.1 mg/l BAP and 1 mg/l 2,4-D. For shoot morphogenesis, 0.1 mg/l BAP and 1 mg/l 2,4-D showed a maximum shoot frequency of 83.33%, whereas the maximum number of shoots/explants (1.87) was observed in 0.1 mg/l BAP or 4 mg/l NAA and maximum shoot length (4.12 cm) was found in 0.01 mg/l BAP. The root morphogenesis was found efcient with NAA applied alone or in combination. The combination of NAA (2 mg/l) and BAP (0.01 mg/l) was found efcient for maximum root frequency (83.33%), while maximum roots/explant (8.70) and root length (4.64 cm) were observed in NAA 4 and 2 mg/l respectively. The regenerated plantlets survived well in the acclimatization process for 3-5 weeks but grew slowly. The plantlets that survived in the laboratory condition got through the greenhouse with a 100% survival rate. The control of various morphogenetic processes as a function of growth regulators has been discussed. Hence, the present study can be applied to the large-scale propagation of species to improve their population.