Abstract:A hydroxyproline (HYP) resistant cell line of Chinese aneurolepidium (Aneurolepidium chinense (Trin.) Kitag. ) was isolated under selection pressure of 20 mmol/L HYP. Comparison of the free amino acid pool levels in the cell line with that of donor showed substantial accumulation of proline (6.6 × ). Enzyme examination indicated that γ-glutamyl kinase controlling proline biosynthesis in HR20-8 cell line had 2.5 times as much activity as that of the donor. Exogenous L-proline inhibited the enzyme activities both in the HR20-8 and the donor by the same rate of 30% at 100 mmol/L. The responses of HR20-8 cell line to NaC1, PEG and cold temperature (5 ℃) were also compared with those of donor and the former exhibited remarkably increased tolerance to the tested stress condition. The results showed that changes of γ-glutamyl kinase property exhibited the phenomenon of extra accumulation of proline which might favor the increased tolerance to NaC1, PEG and cold temperature in the resistant cell line.