外源NO对镧胁迫下燕麦幼苗活性氧代谢和矿质元素含量的影响

为探讨外源NO对稀土元素镧(La)胁迫下燕麦幼苗生理响应的调节作用,采用水培方法,研究了NO供体硝普钠(SNP)对20mmol/L La~(3+)胁迫下幼苗生长、活性氧代谢和矿质元素吸收的影响。结果表明,La~(3+)胁迫下燕麦幼苗根长、株高和植株干重明显下降,根系和叶片活性氧(O_2~(·-)和H_2O_2)水平及丙二醛(MDA)含量显著提高,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性降低,抗坏血酸过氧化物酶(APX)活性及抗坏血酸(AsA)和谷胱甘肽(GSH)含量提高;施加100μmol/L SNP能显著缓解La~(3+)胁迫对燕麦幼苗生长的抑制作用,降低La~(3+)胁迫下燕麦幼苗根系和叶片O_2~(·-)、H_2O_2、MDA、AsA和GSH含量,提高SOD、CAT、POD和APX活性。La~(3+)胁迫提高了燕麦幼苗根系和叶片La和铜(Cu)的富集量,抑制了钾(K)、钙(Ca)、镁(Mg)、铁(Fe)、锌(Zn)、锰(Mn)的吸收;施加100μmol/L SNP可显著抑制燕麦从根系向叶片La的转运,缓解La~(3+)胁迫对K、Ca、Mg、Fe吸收的抑制及对Cu吸收的促进效应,使根系中Zn、Mn含量下降,叶片Zn、Mn含量增加。由此表明,外源NO能够通过提高抗氧化酶活性及影响La的转运和矿质元素吸收,缓解La~(3+)胁迫对燕麦幼苗的氧化伤害和生长抑制。

Effect of exogenous nitric oxide on active oxygen metabolism and mineral contents in oat seedlings under lanthanum stress

The pollution of agricultural systems by rare earth elements has become one of the most serious envi-ronmental deterioration problems worldwide.The signaling molecule nitric oxide (NO)is involved in the plant response to heavy metals.The aim of this study was to investigate the regulating effect of exogenous NO on the physiological response of oat seedlings to lanthanum (La)stress.We conducted a hydroponic experiment in which the exogenous NO donor sodium nitroprusside (SNP)was applied to oat seedlings under a 20 mmol/L La3+ treatment and plant growth,active oxygen metabolism,and the absorption of minerals were investigated. The root length,plant height,and dry weight of oat seedlings were significantly lower in La3+-stressed seed-lings than in control seedlings.Compared with control plants,those treated with La3+ showed significantly in-creased active oxygen (O2 ·- and H2 O2 )and malondialdehyde (MDA)contents in roots and leaves,decreased activities of superoxide dismutase (SOD),catalase (CAT),and peroxidase (POD),and increased ascorbate peroxidase (APX)activity and ascorbic acid (AsA)and glutathione (GSH)contents.Addition of 100μmol/L SNP to oat seedlings under La3+stress significantly alleviated the La3+-inhibition of growth.Compared with La3+-treated seedlings,those treated with La3+ + SNP showed reduced contents of O2 ·-,H2 O2 ,MDA, AsA,and GSH in roots and leaves,and increased activities of SOD,CAT,POD,and APX.Seedlings under La3+stress showed increased La and copper (Cu)accumulation in the roots and leaves,but decreased absorp-tion of potassium (K),calcium (Ca),magnesium (Mg),iron (Fe),zinc (Zn),and manganese (Mn).Com-pared with La3+-treated seedlings,those treated with La3++ SNP showed significantly lower La translocation from roots to leaves,increased absorption of K,Ca,Mg,Fe,increased Cu uptake,lower Zn and Mn contents in roots,and higher Zn and Mn contents in leaves.Consequently,exogenous NO could alleviate the oxidative damage and growth inhibition of oat seedlings under La3+ stress by increasing the activities of antioxidant en-zymes and altering La translocation and mineral absorption.