Abstract: Populus euphratica is an arbor that grows in drought and saline area in Northwest China. This work aims to explore the relation of telomerase activity and oxidative damage resistance. Using Populus euphratica and P. simonii×P. pyramibalis cv callus cells as materials，superoxide anion free radical levels，malondialdehyde contents and telomerase activity under salt stress were investigated. Results indicated that the fresh growth were consistent with sigmoid growth curve in both P. euphratica and P. simonii × P. pyramibalis cv cells，and the growth of P. simonii × P. pyramibalis cv was higher than that of P. euphratica. Compared to the control（0 mmol/L），the cell activity of P. euphratica increased when cultured for 7 days under the treatment of 100 mmol/L NaCl，and maintained at a certain level under the treatment of 300 mmol/L NaCl for 15 days. However，the cell activity of P. simonii × P. pyramibalis cv was affected under low NaCl concentration，and approximated to zero when cultured for 5 days under 300 mmol/L NaCl. Under the treatment of 100 mmol/L NaCl，the content of superoxide anion free radical and telomerase activity in P. euphratica cells increased compared to P. simonii × P. pyramibalis cv cells，while the malondialdehyde content in P. simonii × P. pyramibalis cv cells rose significantly. The telomerase activity in P. euphratica cells was much higher than that in P. simonii×P. pyramibalis cv cells when cultured in 300 mmol/L NaCl. The telomerase activity in P. euphratica cells increased but no significant change in P. simonii×P. pyramibalis cv cells under the low concentration of H₂O₂；high concentration of NaCl or H₂O₂ caused the oxidative damages to both P. euphratica and P. simonii × P. pyramibalis cv cells，resulting in the decrease of telomerase activity. Experimental results suggest that the telomerase can play certain role in defensing oxidative damage.

Key words: Populus euphratica, P. simonii×P. pyramibalis cv, salt stress, telomerase, oxidative damage