羊草根、叶在干旱和盐胁迫下的生理反应

我国北方干旱气候和盐渍化土地严重限制了羊草(Leymus chinensis)生长,为探究羊草在逆境下根、叶的联系与区别,为提高羊草耐盐性和耐旱性提供理论依据,本研究通过设置不同浓度PEG(20%、30%、40%、50%)溶液和NaCl溶液(100、200、300、400mmol·L~(-1)),模拟不同程度干旱和盐生境,测定干旱胁迫和盐胁迫下羊草根、叶抗氧化酶系统(APX、CAT、POD)活性和可溶性蛋白含量的变化,对比羊草根、叶在胁迫下的生理反应。结果显示,轻度盐胁迫下(100mmol·L~(-1)),羊草主要通过叶片的APX消除活性氧自由基,渗透调节部位主要在叶片中;中度盐胁迫(200、300mmol·L~(-1))下,根部、叶部分别主要通过提高POD和CAT活性来消除活性氧;胁迫严重时(400 mmol·L~(-1)),根部APX显著升高,叶片则通过提高POD和CAT活性共同抵抗活性氧的危害,渗透调节也会从叶片转为根、叶共同作用。干旱胁迫初期(20%),羊草主要依靠根、叶中的APX和叶中的CAT来消除活性氧,随着胁迫加重,根中的APX和叶中的CAT活性提高,共同抵抗活性氧危害,根、叶中POD活性一直呈下降状态,对抵抗活性氧自由基伤害作用不大,渗透调节部位主要在叶片中。

Physiological response of leaves and roots of Leymus chinensis under drought and salt stress

The growth of Leymus chinensis was severely restricted by the arid climate and salinized land in north of China.This test contrasts physiological responses of roots and leaves of L.chinensis under stress,to identify the effects on,and differences between,roots and leaves of L.chinensis by simulating different drought and salt conditions.The benefit of this study is to provide a theoretical basis for enhanced salt tolerance and drought tolerance in L.chinensis.Drought stress and salt stress were respectively simulated by different concentrations of PEG solution and NaCl solution.We discuss the activities of antioxidant enzymes(APX,CAT,and POD)and diversification of soluble protein content in the roots and leaves of L.chinensis.Result: Under mild salt stress(100 mmol·L-1),L.chinensis mainly eliminated the ROS through APX of the leaves,and the site of osmotic regulation is mainly in the leaves;under moderate salt stress(200,300 mmol·L-1),the roots and leaves eliminated ROS by increasing activities of POD and CAT,and the roots mainly improved activity of POD,and the leaves mainly enhanced activity of CAT;under severe stress(400 mmol·L-1),APX of the roots was significantly increased,while the leaves were able to resist damage from ROS by increasing POD and CAT activities,and the location of osmotic regulation also changed from leaves,to roots and leaves.In the early stage of drought stress(20%),L.chinensis mainly relied on APX of roots and leaves and CAT of leaves to eliminate ROS.With the stress increase,activities of APX and CAT in roots were increased to resist the damage from ROS,and the activity of POD in roots and leaves kept decreasing,The location of osmotic adjustment was mainly in leaves.