外源NO对镉胁迫下草地早熟禾幼苗根系生长及生理的影响

Effects of exogenous NO on physiological characteristics of kentucky bluegrass under cadmium stress

为了探究外源NO对镉胁迫下草地早熟禾幼苗生理特性的影响,以草地早熟禾品种午夜(Poa pratensis cv.Midnight)为试验材料,研究在1000μmol/L的镉胁迫下,50μmol/L的外源NO对镉胁迫的缓解效应,试验共设置4个处理CK(蒸馏水)、Cd、NO、Cd+NO。NO供体硝普钠(SNP)采用叶面喷施,Cd处理采用根部施入,测定NO对草地早熟禾幼苗叶片相对含水量、丙二醛含量、游离脯氨酸含量、抗氧化酶活性及根系总根长、根表面积、根尖数、分支数、交叉数的影响。结果表明:Cd胁迫可降低早熟禾相对含水量,抗氧化酶活性,增加MDA和脯氨酸的积累,抑制根系生长;Cd胁迫下添加NO可增加草地早熟禾叶片相对含水量,提高抗氧化酶活性,减少MDA和游离脯氨酸的累积,增加总根长、总根表面积、根尖数、分支数、交叉数。试验表明1000μmol/L的镉胁迫可加重草地早熟禾氧化损伤,抑制草地早熟禾幼苗生长,施加50μmol/L NO可提高抗氧化酶活性,降低游离脯氨酸的累积和促进根系生长,缓解镉胁迫对草地早熟禾的生长抑制。

The main purpose of this paper was to study the effects of exogenous nitric oxide on physiological characteristics of Kentucky bluegrass under cadmium stress.Taking Kentucky bluegrass variety‘midnight’as experimental material,the mitigation effect of exogenous nitric oxide(50μmol/L)on the seedlings of bluegrass under cadmium stress(1000μmol/L)was studied.A total of 4 treatments including CK,Cd,NO and Cd+NO were set in the experiment.NO donor sodium nitroprusside(SNP)was sprayed by foliar spraying,while Cd treatment was applied by root application.The leaf relative water content,malondialdehyde(MDA)content,free proline content,antioxidant enzyme activity and roots morphology indexes were measured.The results showed that under cadmium stress,the relative water content and antioxidant enzyme activity of bluegrass decreased,MDA and free proline accumulation increased,and root growth was inhibited.The application of SNP can promote relative leaf water content,increase the activity of antioxidant enzyme,reduce the content of MDA and free proline,increase total root length,total root surface area,number of root tips,number of branches,and number of intersections.It indicated that the oxidative damage of Kentucky bluegrass was aggravated and seedling growth was inhibited under cadmium stress(1000μmol/L),exogenous NO could alleviate cadmium stress of Kentucky bluegrass by increasing the activity of antioxidant enzymes,reducing the accumulation of free proline and promoting root growth.