外源水杨酸对苜蓿幼苗盐胁迫的缓解效应

Exogenous salicylic acid on alleviating salt stress in alfalfa seedlings

为明确外源水杨酸提高苜蓿抗盐的生理生化机制,以"甘农3号"苜蓿品种为材料,在150mmol/L NaCl胁迫条件下,采用叶面喷施方法,研究外源水杨酸(salicylic acid,SA)对苜蓿幼苗生长、有机渗透调节物质含量及抗氧化系统的影响。结果表明,盐胁迫显著抑制了苜蓿幼苗生长,盐胁迫下添加0.25mmol/L外源SA后,苜蓿幼苗的株高、根长、鲜重,植株叶绿素含量显著升高,叶片和根系中游离脯氨酸、丙二醛(MDA)含量显著降低,可溶性蛋白含量显著增加;叶片中超氧化物歧化酶(SOD)、愈创木酚过氧化物酶(GPX)和抗坏血酸过氧化物酶(APX)活性显著升高,过氧化氢酶(CAT)活性、抗坏血酸(AsA)和还原型谷胱甘肽(GSH)含量未发生变化;根系中GPX活性、AsA和GSH含量显著升高,SOD、CAT和APX活性则未发生变化,说明外源SA处理能调控苜蓿幼苗有机渗透调节物质含量和抗氧化保护系统,缓解盐胁迫对苜蓿植株的伤害。

In order to make clear the physiological and biochemical mechanisms of exogenous salicylic acid（SA） on salt resistant capability of alfalfa,Medicago sativa cv.Gannong No.3 was used as material to study the effect of exogenous SA on alfalfa seedling growth,organic osmotic regulation substance contents and anti-oxidization system on condition of 150 mmol/L NaCl stress using foliar application.The result indicated that 150 mmol/L NaCl salt stress had conspicuous inhibitory effect on alfalfa seedling growth,while significant increase in shoot heigth,root length,fresh weight and plant chlorophyll content were found when 0.25 mmol/L exogenous SA had been applicated,together with significant decrease in free proline and malondialdehyde（MDA） contents in leaves and rootsand increase in soluble protein;superoxide dismutase（SOD）,guaiacol peroxidase（GPX） and ascorbate peroxidase（APX） activities in leaves were found significantly increased,and no change was found in catalase（CAT）,ascorbic acid（AsA） and reduced glutathione（GSH）;for the root,GPX activity,AsA and GSH contents were found increased,and no change was found in SOD,CAT and APX activities,indicating that exogenous SA could regulate organic osmotic regulation substances and protect the anti-oxidization system in alfalfa seedling,and alleviate the injure of salt stress on alfalfa plants.