不同形态硒对盐胁迫下小麦苗期光合生理、抗氧化系统及离子稳态的影响

Effects of Different Selenium Forms on Photosynthetic Physiology,Antioxidant System and Ion Homeostasis of Wheat Seedlings under Salt Stress Yang

为了解盐胁迫下不同形态硒(Se)及其组合对小麦耐盐机制的影响,本试验以无盐胁迫为对照(CK),设置盐胁迫处理(SS)及盐胁迫下施用纳米硒(SeNPs)、亚硒酸钠(SeIV)、硒代蛋氨酸(SeMet)处理及其复合施用处理[SeNPs+SeIV、SeNPs+SeMet、SeIV+SeMet、Se(NPs+IV+Met)],研究不同形态硒对盐胁迫下小麦光合生理、抗氧化系统及离子稳态的影响。结果表明,盐胁迫下小麦光合生理受到显著影响,抗氧化产物累积增加,离子稳态失衡。盐胁迫下不同形态硒及其组合处理提高小麦叶片光合色素(叶绿素a、叶绿素b、类胡萝卜素)含量,改善叶绿素荧光参数(Fv/Fm、ΦPSⅡ、NPQ、qP),减轻盐胁迫对叶绿体损伤,激活抗氧化酶(SOD、CAT、APX),降低脂质过氧化物(LPO)、超氧阴离子自由基(O_(2)^(·)^(-))、过氧化氢(H_(2)O_(2))含量,上调表达相关盐调控基因(TaAOX、TaSOS1、TaNHX1),整体而言以含SeNPs的组合处理[SeNPs+SeIV、Se(NPs+IV+Met)]效果较优。此外,盐胁迫下,与CK、SS和不同形态硒单施相比,SeNPs+SeIV、Se(NPs+IV+Met)处理植株Se、K含量显著增加,Na含量显著降低,K/Na比值增加,SeNPs+SeIV处理整体优于Se(NPs+IV+Met)处理。综上,盐胁迫下不同形态硒及其组合处理均可保护叶片光合色素降解、提高光合效率、激活抗氧化防御系统、诱导盐调控基因表达上调,并通过增加植株Se、K含量和降低Na吸收维持植株离子稳态从而缓解盐分胁迫,且整体以纳米硒与亚硒酸钠组合施用(SeNPs+SeIV)效果最佳。

To understand the mechanisms of different forms of selenium(Se)and their combinations on the salt tolerance of wheat,the salt stress treatment(SS),the application of selenium nanoparticles(SeNPs),sodium selenite(SeIV),selenomethionine(SeMet)and their combinations including SeNPs+SeIV,SeNPs+SeMet,SeIV+SeMet and Se(NPs+IV+Met)were set with no salt stress as control(CK)in this experiment.Their effects on photosynthetic physiology,antioxidant system and ion homeostasis of wheat were studied under salt stress.The results showed that the photosynthetic physiology of wheat was significantly affected by salt stress with the accumulation of antioxidant substances increasing and the ion homeostasis imbalanced.Under salt stress,all the selenium treatments increased the content of photosynthetic pigments(chlorophyll a,chlorophyll b,carotenoids)in wheat leaves,improved chlorophyll fluorescence parameters(Fv/Fm,ΦPSⅡ,NPQ,qP),activated antioxidant enzymes(SOD,CAT,APX),reduced lipid peroxide(LPO),superoxide anion radical(O_(2)^(·)^(-))and hydrogen peroxide(H_(2)O_(2))contents and upregulated the expression of related saltregulated genes(TaAOX,TaSOS1,TaNHX1);overall,the combination treatment with SeNPs[SeNPs+SeIV,Se(NPs+IV+Met)]had better effect.Furthermore,under salt stress,compared with CK,SS and single application of all the selenium forms,the SeNPs+SeIV and Se(NPs+IV+Met)treatments increased Se and K contents and decreased Na content significantly,resulting in increase of K/Na ratio,SeNPs+SeIV treatment was more effective than Se(NPs+IV+Met)treatment.In summary,under salt stress,different forms of selenium and their combinations could inhibit the degradation of photosynthetic pigments in leaves,improve photosynthetic efficiency,activate antioxidant defence system,induce upexpression of saltregulated genes,and maintain wheat ion homeostasis by increasing Se and K content and reducing Na absorption to alleviate salt stress;the combination of selenium nano-selenium and sodium selenite(SeNPs+SeIV)had the best effects.