High frequency somatic embryogenesis in Ceropegia spiralis Wight--An endemic and endangered medicinal plant

Plant regeneration through direct somatic embryogenesis in Ceropegia spiralis was achieved in the present investigation. Callus was obtained from nodes, internodes and thin cell layers (TCLs) of the plant. Explants were cultured on Murashige and Skoog (MS) medium supplemented with N-6-benzyl amino purine (BAP) with different concentrations of auxins. Extensive callusing of TCLs (99.93 plus or minus 0.26%) was observed on the medium containing BAP (13.32 mu M) with 2,4 dichlorophenoxy acetic acid (2,4-D, 4.52 mu M). On MS medium supplemented with kinetin (Kn, 4.56 mu M)+casein (250 mg/L) the highest number (8.40 plus or minus 1.14) of germinating somatic embryo was noticed. The ontogeny of the somatic embryos was also observed. The emblings were transferred to pots containing vermiculite and coco peat in 1:1 ratio. On transfer to the shaded green house for hardening, vigorous growth of plantlets was observed. Eventually, plantlets were transferred in the open field after 50 d with 85% survival rate.