Abstract: We optimized a rapid, effective system of plant regeneration by direct shoot regeneration and organogenesis in an endangered tree, the living fossil Metasequoia glyptostroboides. We studied the influence of plant growth regulators on explant types (embryo, root, stem and young leaf). Callus could be induced by different types of explants on MS medium supplemented with different combinations of 2,4-D, NAA and 6-BA. The frequency of callus induction was highest (100%) with  embryo used as explants, then with stem (97.1%). The best media for callus induction on embryo was MS+1.0 mg·L^–1 2,4-D+0.5 mg·L^–1 6-BA, MS+0.1 mg·L^–1 6-BA+1.0 mg·L^–1 NAA, MS+0.5 mg·L^–1 6-BA+1.0 mg·L^–1 NAA, MS+1.0 mg·L^–1 6-BA+1.0 mg·L^–1 NAA, MS+0.5 mg·L^–1 6-BA+2.0 mg·L^–1 NAA, MS+1.0 mg·L^–1 6-BA+2.0 mg·L^–1 NAA and MS+0.5 mg·L^–1 2,4-D+0.5 mg·L^–1 NAA. More regenerated plants were obtained on MS medium, with a frequency of 62.5%.

Key words: Metasequoia glyptostroboides, plant regeneration, rate of induction, tissue culture