A Sustainable Approach to In Vitro Propagation and Conservation of Salvia dominica L.: A Wild Medicinal Plant from Jordan

Salvia dominica L. is an important wild medicinal plant that grows in Jordan and neighboring countries, and this plant has been suffering from many threats in its wild environment. Therefore, this research aims to establish a comprehensive and sustainable approach via an in vitro propagation and conservation system for the S. dominica L. plant. Axillary buds were used to initiate the in vitro culture on Murashige and Skoog MS media supplemented with 0.5 mg L⁻¹ of GA₃. In vitro shoot proliferation and rooting were experimented on with different concentrations of cytokinins and auxins, respectively. Calli were induced in the dark on excised leaf discs (0.5 cm in diameter), and multiplication was experimented on with different growth regulators. Cryopreservation experiments were applied on the callused segments under different growth conditions via the vitrification technique. A full protocol was achieved for shoot proliferation with 6.3 shoots/explant using 1.2 mg L⁻¹ of thidiazuron (TDZ), while rooting was achieved at 1.5 mg L⁻¹ of NAA with 6.6 functional roots/explant. Acclimatization was completely successful for the rooted plants. The highest callus production with 5.81 g/calli was achieved using 1.5 mg L⁻¹ of benzylaminopurine (BAP). Cryopreservation of the S. dominica calli was successfully achieved when a pure plant vitrification solution (PVS2) was used to dehydrate the calli for 20 min after immersion in the loading solution for 20 min with a 76.6% regrowth percentage. The loading and the plant vitrification solution type and duration were the most critical points in the regrowth of the cryopreserved calli. In conclusion, a successful protocol was set up for the in vitro propagation and conservation of S. dominica calli. This study has prompted us to perform further studies on sustainable in vitro production and conservation of critically endangered medicinal plants to implement a green environment protecting against surrounding threats.