Clonal Micropropagation Technology of Relict Gymnosperms Sequoia sempervirens (D. Don) Endl.

Sequoia sempervirens (D. Don) Endl. is the tallest relict plants capable of accumulating unique secondary metabolites that can be used in pharmacognosy. Given the documented reproductive vulnerability of the coast redwood, biotechnological methods for establishing in vitro genetic banks and bioresource collections are increasingly relevant for the preservation of its gene pool. This study utilized nodal segments of S. sempervirens harvested from a donor tree maintained in the stock greenhouse of the N.V. Tsitsin Main Botanical Garden of the Russian Academy of Sciences (Moscow). The research investigates the effects of mineral and hormonal nutrient media compositions, as well as the explant’s original position on the shoot, on in vitro propagation efficiency. Stepwise sterilization using a 0.1 % (w/v) mercuric chloride solution for 18 min resulted in a successful sterile culture rate exceeding 80 %. Findings indicate that explants should initially be cultured on a hormone-free Murashige and Skoog (MS) basal medium, followed by a proliferation medium supplemented with either 2 mg/L 2,4-D + 0.5 mg/L BAP + 0.5 mg/L NAA or 2 mg/L 2,4-D + 2 mg/L 2iP for effective multiplication. For rooting, it is advisable to transfer regenerants to a medium containing 2 mg/L 2,4-D + 0.5 mg/L BAP + 0.5 mg/L NAA. Following the development of the root system, the resulting clones are prepared for ex vitro transfer. Acclimatization is conducted in a soil substrate under a polyethylene cover with a 16-hour photoperiod to support the transition to ex vitro conditions. Acknowledgements: The team of authors expresses its gratitude to Anton V. Kucherov, agronomist of the N.V. Tsitsin Main Botanical Garden of the Russian Academy of Sciences, for providing plant material. The study was carried out as part of the research project No. 24-76-00070.