Plant Regeneration through Somatic Embryo in Herpetospermum pedunculosum, an Endangered Tibetan Medicinal Herb

Objective An effective reproducible protocol for complete plant regeneration via somatic embryogenesis has been developed for Herpetospermum pedunculosum, an endangered Tibetan medicinal herb. Methods The cotyledon explants used in this study were excised from seedlings germinated in vitro. Callus was induced from cotyledon explants on Murashige and Skoog’s medium, supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D, 0.1–1.0 mg/L) alone or in combination with 6-benzylaminopurine (BA, 0.5, 1.0, and 2.0 mg/L). Results The calli showed differentiation of globular embryos after three weeks of incubation on MS medium supplemented with various combinations of BA and NAA. Sixty-two percent of the embryogenic calli produced somatic embryos in MS basal medium supplemented with BA (1.0 mg/L) + NAA (2.0 mg/L). The addition of KN (0.5 mg/L) to MS medium containing both BA and NAA (2.0 mg/L each) significantly increased the frequency of somatic embryogenesis. The maximum percentage of embryogenic calli formation was 83%, and globular embryos formed and germinated successfully in this medium. Then, transferring the regenerated plants from this medium to hormone-free MS medium will further enhanced the development of the plants, and the healthy plantlets are formed successfully within four weeks. The plantlets were transferred to soil to acclimatize under greenhouse conditions and 75% survived. Conclusion Somatic embryogenesis protocol as reported here can play a key role in the propagation and conservation of this endangered species.