Abstract: Cell-suspension cultures derived from the calli initiated from plumalar axis of Oxytropis leptophylla were used for studying the effects of different enzymes, phytohormones and osmotic pressure in medium (e. g. the content of glucose) on protoplast isolation and culture. The results showed that the protoplasts were easy to damage into small segments when osmotic pressure was out of balance for protoplats' protoplasm. It was also found that the low osmotic pressure acted similarly to 2,4-D at high concentration in inducing the cell budding division, which resulted in death of cells. The optimum osmotic pressure and phytohormones combination was determined.

Key words: Oxytropis leptophylla, Protoplast, Phytohormone, Osmotic pressure, Cell-suspension