甘露糖对镉胁迫下小麦生长、镉转运和氧化胁迫的影响

Effects of mannose on wheat(Triticum aestivum L.)growth,cadmium transport and oxidative stress under cadmium stress

[目的]本文旨在阐述喷施甘露糖缓解小麦镉(Cd)胁迫和抑制Cd转运的分子机制。[方法]测定小麦生长、生理、生化指标和分析根系蛋白组学差异,经过KEGG和GO注释方法分析差异蛋白所涉途径的相关信息,进一步用Real-time PCR验证差异表达蛋白。[结果]甘露糖处理15 d后,小麦根长和根干重分别增加54.8%和29.5%;地上部Cd总含量减少33.6%,而地下部增加58.1%。Cd转运系数减小47.7%,小麦Cd转运被抑制。叶片和根中谷胱甘肽(GSH)含量分别增加11.1%和42.8%,氧化型谷胱甘肽(GSSG)含量分别减少43.2%和49.3%。叶片和根活性氧分子的积累减少,表明小麦所受氧化胁迫减轻。甘露糖处理后,谷胱甘肽还原酶(GR)活性明显升高,过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性没有明显变化。处理后根中共有222个蛋白质发生显著变化,分别属于谷胱甘肽代谢、氮代谢、磷酸戊糖途径(PPP)、糖酵解/糖异生、氰氨基酸代谢、次生代谢产物和苯丙烷生物合成等途径。其中,谷胱甘肽代谢途径中有5个谷胱甘肽-S-转移酶(GST)差异丰度蛋白(DAP),选择其中差异变化最大的GSTU6用于Real-time PCR验证,其表达量显著增加,合成GSH前体物的GLN1-2以及Prx135的表达量也显著增加。[结论]甘露糖能增强谷胱甘肽清除活性氧能力,缓解小麦Cd胁迫,减少Cd转运。

[Objectives]This article aimed to explore the molecular mechanism of mannose spraying to relieve wheat cadmium stress and inhibit cadmium transfer.[Methods]The growth,physiological and biochemical indexes,as well as the comparation proteomics of root were assayed.Relevant information of the pathway involved in the differential proteins through the KEGG(Kyoto encyclopedia of genes and genomes)and GO(gene ontology)annotation was analyzed,and the differential protein expressions by real-time PCR were further verified.[Results]After 15 days of mannose treatment,the root length and root dry weight increased significantly by 54.8%and 29.5%,respectively.The total amount of Cd decreased by 33.6%in shoot,while increased by 58.1%in root.Moreover,the transport coefficient decreased by 47.7%,which indicated Cd transfer was inhibited.The glutathione(GSH)content in leaves and roots increased by 11.1%and 42.8%,respectively,while the oxidized glutathione(GSSG)content decreased by 43.2%and 49.3%,respectively.The accumulation of reactive oxygen molecules in leaves and roots were reduced,which alleviated oxidative stress.After mannose treatment,there was no significant change in catalase(CAT)and superoxide dismutase(SOD)activities except glutathione reductase(GR)activity.A total of 222 proteins in the roots changed significantly after treatment,belonging to metabolism pathways,i.e.glutathione metabolism,nitrogen metabolism,pentose phosphate pathway,glycolysis/gluconeogenesis,cyanoamino acid metabolism,secondary metabolite biosynthesis and phenylpropane synthesis.There were 5 glutathione-S-transferase(GST)differential abundance proteins(DAP)in the glutathione metabolic pathway,and the GSTU6 with the largest variation was selected for verification by real-time PCR,and its expression results significantly increased.In addition,the expression of GLN1-2 which affected the synthesis of GSH precursors and Prx135 which affected the clearance of peroxides significantly increased.[Conclusions]Mannose promoted the glutathione to remove active oxygen species,which relieved cadmium stress and block cadmium transport in wheat.