Synthetic Seed Production as a Tool for the Conservation and Domestication of Celastrus paniculatus: A Rare Medicinal Plant

The black-oil tree (Celastrus paniculatus Willd) is a highly valued medicinal plant species belong to the Celastraceae family, known as Jyothishmathi in Ayurveda and Duhundu in Sri Lanka and grows as a perennial vine. It is an endangered medicinal plant species recorded in the red list of endangered fauna and flora of Sri Lanka in 1999. The seed oil of Celastrus paniculatus contains sesquiterpene alkaloids namely; celapagine, celapanigine, celapanine and celastrol, used in traditional system of medicine for various disorders and because of its high pharmaceutical value, plants are over exploited in natural habitats. Owing to poor seed germination and lack of successful vegetative propagation methods, domestication and commercial planting of this important medicinal plant species to meet the demand seems impossible. Therefore, it is of high importance to develop a reliable and efficient in vitro propagation to produce black oil plants for commercial use. In this study, it was attempted to produce synthetic seeds of Celestrus paniculatus via in vitro multiple shoot proliferation. Nodal segment explants were collected from freshly emerged age of sprouts, surface sterilized and cultured in Murashige and Skoog medium supplemented with different 6-benzylaminopurine (BAP) and Thidiazuron (TDZ) concentrations for shoot induction. The highest soot proliferation rate; 25 shoot tips/explant were observed with 0.1 mg/L TDZ. Induced shoot tips were used for synthetic seed production after encapsulating with BAP and a-naphthalene acetic (NAA) enriched sodium alginate. Shoot tip encapsulated beads produced with 4% sodium alginate were firm, clear, round and uniform in size and easy to handle. The influence of growth regulators (BAP and NAA) and storage period on the germination of encapsulated shoot tips was studied to evaluate the success of encapsulated shoot tips as a propagule. The beads germinated with 2 mg/L BAP and 0.2 mg/L NAA provided 80% in vitro germination percentage. Shoot tips of synthetic seeds remained green and healthy after storage at 5°C for a period of 8 weeks. Current findings suggest that encapsulated micro shoots (synthetic seeds) could be produced successfully, as the first step in domestication and conservation of Celastrus paniculatus. Further studies required on rooting of micro shoots, acclimatization and transferring of plantlets produced from synthetic seeds to in vivo conditions for domestication and conservation purposes.