Effect of spermidine on seed germination and physiological characteristics of Perilla frutescens seedlings under NaCl stress

Objective In order to get the method for improving the salt resistance of Perilla frutescens seeds and seedlings under NaCl stress,the seed germination and physiological characteristics of P.frutescens seedlings were studied.Methods Several physiological indexes of P.frutescens seeds under NaCl stress,such as the germination vigor(Gv),germination rate(Gr),and germination index(Gi),were measured.And other indexes of the seedlings like relative water contents(RWC),malondialdehyde(MDA),superoxide(SOD),peroxidase(POD),and catalase(CAT) were also measured.Results The germination indexes of P.frutescens seeds under NaCl stress was inhibited obviously inhibition.But after the treatment by spermidine(Spd) at the different concentrations,every germination indexes were all increased.And the seeds treated by Spd with the concentration of 0.25 mmol/L had the most significant increase in every index.The Gv was 59.7%,the Gr and Gi were 69.4% and 12.8,respectively.The RWC and total flavonoids in P.frutescens leaves decreased under NaCl stress,but after treated by Spd,the rate of decrease had been relieved and the content of MDA was decreased.The activities of three enzymes including SOD,POD,and CAT were increased by the treatment of Spd,and got the maximum(72.4 U/g,8.7 and 8.8 U/mg,respectively) with the concentration of 0.25 mmol/L were got.Conclusion Spd with the concentration of 0.25 mmol/L could significantly alleviate the damages to the seeds and seedlings of P.frutescens under NaCl stress,and promote the salt resistance to the seeds and seedlings of P.frutescens.