Abstract: A study has been undertaken to investigate the effects of kinetin on the telomerase activity and physiological characteristics of wild Elymus sibiricus seedlings under different levels of salt stress in order to provide a scientific basis for agricultural production in areas with severe soil salinization and the improvement of artificial grassland. Wild E. sibiricus were collected from Qinghai-Tibet Plateau alpine grassland in 2015 and used as test material in sand culture experiments. When the third leaf of the seedlings extracted and unfolded, the seedlings were treated with sodium chloride (NaCl) solution at different concentration levels (0, 50, 100, 150, 200 mmol·L^-1) for 168 hours. The seedlings’ leaves were then sprayed with kinetin solutions of different concentrations (0, 5, 10, 20, 30 mg·L^-1) for 240 hours and measurements taken of telomerase activity and physiological parameters: chlorophyll, free proline (Pro), malondialdehyde (MDA), soluble sugar (SS), and soluble protein (SP) content. The results showed that with the increase of salt stress, telomerase activity firstly increased and then decreased, peaking under the 50 mmol·L^-1 NaCl treatment. When NaCl concentrations were higher than 50 mmol·L^-1, telomerase activity decreased and the content of free proline, soluble sugar and soluble protein increased with increasing salt stress, among which the SS increment (101.5%) of seedlings under 250 mmol·L^-1 NaCl was significantly different from that of the control (P<0.05). Following spraying with 10 mg·L^-1 kinetin, the MDA content of seedlings treated with 0 mmol·L^-1 NaCl decreased by 64.9%. High concentrations of kinetin can significantly relieve the salt stress of seedlings (P<0.05), with chlorophyll content (under 250 mmol·L^-1 NaCl stress) and SS content (under 100 mmol·L^-1 NaCl stress) increasing by 17.3% and 165.6% respectively after spraying with 20 mg·L^-1 kinetin.These results indicate that exogenous kinetin alleviates salt stress to some extent. Suitable NaCl concentrations induced telomerase activity, whereas high concentrations of NaCl stress may cause oxidative damage to E. sibiricus cells and result in decreased telomerase activity.

Key words: Elymus sibiricus, telomerase activity, salt stress, physiological characteristics