Abstract: Protoplasts isolated from suspension cell lumps of Medicago lupulina L. started to divide after 2 clays in K8p culture medium containing 0. 1～2.0 mg/L of 2, 4-D, with a maximum division frequency of 38. 35%. After S weeks of culture, the protoplast-derived cell lumps were transferred to liquid/solid double-layer media for microcallus regeneration, with a maximum frequency of 0.58%. The whole plants were regenerated from protoplastderived calli via somatic embryogenesis and organogenesis. In somatic embryogenesis, the embryoids were induced on MS and W14 media with rather wide range (1. 0420.0 mg/L) of 2, 4-D concentration. The highest induction frequency of embryoids was 71.0%. In organogenesis, the differentiation media containing lower concentration of 6-BA (0. 5～0. 7 mg/L) were suitable for adventitious bud formation. The highest frequency of adventitious bud formation from calli was 27. 8%. The mature protoplast-regenerated plants were obtained 3 months after transplanting the plantlets into soil.

Key words: Medicago lupulina, Protoplast culture, Somatic embryogenesis, Organogenesis, Plant regeneration