Preliminary Study On Salt Tolerance Regulated By Polyamines In Arabidopsis Thaliana

Salt stress could cause changes in polyamines levels in plant tissues,and exogenous polyamines enhanced salt tolerance of plant.However the mechanism of the effect of exogenous polyamines still remains unclear.In the paper,we chose Arabidopsis thaliana as a studying material,the alleviative effects on salinity of different polyamines at different concentrations were compared.In addition,endogenous polyamine contents of Arabidopsis seedlings under different NaCl concentrations were determined,combining with exogenous spermine treatment for Arabidopsis salinity,the relationships between polyamine metabolism and Arabidopsis salt tolerance were studied.The main results were as follows:The growth of Arabidopsis seedlings was obviously suppressed under 100 mmol/L NaCl treatment,and the alleviative effect on Arabidopsis salinity of four exogenous polyamines(putrescine,Put;cadaverine,Cad;spermidine,Spd;spermine,Spm) at different concentrations were investigated.After applying 0.01 mmol/L Spd and 0.01 mmol/L Spm respectively,the length of root elongation and the dry and fresh weight of per plant increased to some different extent,and 0.01 mmol/L Spm had the best alleviative effect on the salt damage of Arabidopsis.However,the effect of 1 mmol/L Put and 0.05 mmol/L Cad appeared not to be significant compared with Spd and Spm.Three forms of endogenous polyamine contents of Arabidopsis under different NaCl concentrations were determined,it showed that the PCA soluble Spd content was provoked by 50 mmol/L NaCl treatment.Besides,free form and PCA soluble Spd contents obviously decreased while Spm content increased with the rising of NaCl concentrations in Arabidopsis seedlings.The free Put content decreased under 150 mmol/L NaCl treatment for 7 days,under the other concentration and time treatment,three forms of Put contents did not mainly change.There was no distinct changes in three forms of Cad caused by salt stress.Comparing with the free polyamines and PCA soluble polyamines,the PCA insoluble polyamines changed unconspicuously under salt stress.The contents of total polyamines reduced significantly as the treatment time was prolonged. The Arabidopsis was treated with 0.01 mmol/L exogenous Spm,which significantly ameliorated Arabidopsis damage caused by 100 mmol/LNaCl stress.The increase of MDA content and electrolytic leakage of leaves were restrained effectively,the content of Na~+ decreased and the content of K~+ increased,resulting in the decrease of the ratio of Na~+/K~+ in Arabidopsis seedlings.It is suggest that exogenous Spm alleviated the salt damage of Arabidopsis through regulating the ion balance of Arabidopsis.