过表达TaLEA1和TaLEA2基因提高转基因拟南芥的耐盐性

我国土壤盐碱化日益严重,对我国的粮食安全造成了严重威胁。耐盐基因挖掘对作物耐盐育种非常重要。LEA蛋白家族是一个多基因家族,在植物应对非生物胁迫中发挥重要作用。本课题组前期研究阐明小麦TaLEA1基因在拟南芥中过表达可以提高转基因植物的耐盐性和抗旱性。本研究系统分析了小麦TaLEA2基因表达蛋白的理化性质、基因表达模式及启动子功能区域,并在拟南芥中过表达TaLEA2基因及共表达TaLEA1和TaLEA2基因,分析TaLEA2基因的抗逆功能及2个LEA基因的抗逆效果。结果表明,TaLEA2基因的表达产物属于第3组LEA蛋白,是稳定的亲水蛋白,富含α-螺旋、β-转角等结构。TaLEA2基因在小麦根、茎、叶、花、种子等不同组织中均有表达,盐胁迫条件诱导其高表达。在拟南芥中过表达TaLEA2基因,或过表达TaLEA1和TaLEA2基因都能够提高转基因拟南芥的耐盐性和抗旱性,转基因株系的种子萌发率、根长及叶绿素含量显著高于野生型,且双基因过表达的转基因植物的抗逆能力高于单个基因过表达株系。本研究结果为LEA基因抗逆机理的研究和多基因共转提高植物抗逆性提供了重要信息。

Overexpression of TaLEA1 and TaLEA2 genes improves salt tolerance in Arabidopsis

Soil salinization is becoming more and more serious in cultivated land in China,which poses a major threat to China's food security.Identifying novel genes conferring salt tolerance and understanding their functions in salt stress adaptation are vitally important for improving crop stress tolerance.The late embryogenesis abundant (LEA) proteins,usually encoded by a multigene family in higher plants,play a positive role in plant response to abiotic stress.We have previously shown that overexpression of TaLEA1,originally isolated in wheat,conferred salt and drought tolerance in Arabidopsis.In this study,we isolated TaLEA2 gene from wheat,analyzed the physical and chemical properties of its deduced protein,determined its expression pattern and promoter region,and examined its function through overexpression in Arabidopsis.Furthermore,we reported the effects of simultaneous overexpression of TaLEA1 and TaLEA2 genes in transgenic Arabidopsis.The results showed that TaLEA2 belonged to the third group of LEA proteins.TaLEA2 was likely a stable hydrophilic protein and rich in α-helix and β-turn,thus providing a structural basis for its function in stress tolerance.TaLEA2 expression was detected in wheat root,stem,leaf,flower and seed tissues,and up-regulated by high salt treatment.Overexpression of TaLEA2 alone,or TaLEA1 and TaLEA2 simultaneously,conferred salt and drought tolerance in Arabidopsis,with the transgenic lines exhibiting higher seed germination rate,longer root length and higher chlorophyll content than the wild type (WT) controls.More importantly,the double overexpressors displayed a higher level of stress tolerance than single overexpressors and WT controls.This study generated valuable information on the function of wheat LEA genes in salt and drought stress,which may facilitate the deployment of these genes in enhancing crop tolerance to abiotic stresses in the future.