过量表达Trxs对铝胁迫下转基因大麦幼苗根系抗氧化酶系的影响

Effects of Overexpressing Trxs on Antioxidant Enzymes Activities in Transgenic Barley Seedling Roots under Aluminum Stress

为了解硫氧还蛋白的过量表达对提高植物抗铝毒能力的作用,以过量表达硫氧还蛋白S基因(Trxs)的转基因大麦为材料,采用水培法研究0.05 mmol/L AlCl3胁迫条件下转基因大麦株系(LSY-11-1-1)幼苗根系谷胱甘肽过氧化物酶(GSH-PX)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)等抗氧化酶活性的变化,以及蛋白质和膜脂氧化损伤程度。结果表明,(1)在0.05 mmol/L AlCl3处理下,大麦幼苗根中蛋白质羰基含量和丙二醛含量显著高于非胁迫处理样品,但是转基因大麦的蛋白质羰基含量和丙二醛含量显著低于非转基因对照,如在铝胁迫处理的6、24、48、72和96 h时转基因大麦幼苗根中蛋白羰基含量分别只有对照的68.13%、52.39%、56.18%、58.02%和60.48%,MDA含量分别是对照的71.26%、74.47%、83.05%、73.65%与75.31%。(2)胁迫处理下大麦根系GSH-PX、CAT和APX等抗氧化酶活性出现不同程度的增加;与非转基因对照相比,转基因大麦幼苗根系抗氧化酶系的活性普遍高于对照,如GSH-PX活性在处理的3、24、48、72和96 h时分别是对照的1.1、1.2、1.8、1.6和1.6倍;APX在活性高峰时分别是对照的121%(3h)和119%(96 h);CAT活性在胁迫处理的3、12、24、48和72 h分别比对照提高了62%、11%、7%、34%和17%,而且转基因幼苗根系CAT活性高峰(处理3 h)比对照提前出现21 h(处理24 h)出现。这些结果表明过量表达Trxs可以有效地提高上述抗氧化酶类的活性,缓解铝毒对大麦根系蛋白质和膜脂的氧化损伤,从而提高转基因大麦幼苗对铝胁迫的抗性。

The barley variety,LSY and its transgenic line overexpressing Trxs were employed to measure the antioxidant enzyme activity,protein oxidative damage and lipid peroxidation damnification under aluminum（Al）stress（0.05 mmol/ L） with hydroponic method.The results showed that（1） the degrees of protein oxidative damage and lipid peroxidation damnification in roots of the transgenic barley seedling was much less than the wild type（non-transgenic barley） as reflected by lower contents of protein carbonyl and malonaldehyde in the transgenic line.Carbonyl content in transgenic barley is only 68.13%,52.39%,56.18%,58.02% and 60.48% of that of wild type at 6 h,24 h,48 h,72 h and 96 h after exposed to Al stress,respectively.Moreover MDA content is 71.26%、74.47%、83.05%、73.65%,and 75.31% of that of the non-transgenic barley.（2） In comparison with non-transgenic barley,activities of glutathione peroxides（GSH-PX）,catalase（CAT） and ascorbate peroxides（APX） in the transgenic barley roots were generally higher,although these antioxidant enzyme activities give a rise to different degrees under the aluminum stress.For example,the GSH-PX activity of transgenic barley seedling were 1.1,1.2,1.8,1.6 and 1.6 times of the non-transgenic barley at 3,24,48,72 and 96 h after the aluminum treatment,respectively.Similar increase was observed in CAT,its activity is 62%,11%,7%,34% and 17% greater than the non-transgenic seedling,respectively at 3,12,24,48 and 72 h on the presence of aluminum.What＇s more,the transgenic line reached the CAT activity peak earlier about 21h than the non-transgenic line.At the peak of the activity,that of APX is 121% of the non-transgenic barley at 3 h and 119 % at 96 h.All the results indicate that overexpressing Trxs efficiently enhances the antioxidant enzymes activities in the root of transgenic barley seedling and relieves the aluminum toxicity to the protein oxidative damage and lipid peroxidation damnification.It is possible that Trxs improved the tolerance of Al3＋ in transgenic barley through increasing the antioxidant enzymes activity,such as GSH-PX,CAT and APX.These properties raise the possibility that transgenic barley could find application in reducing the stress caused by aluminum in acid soils in the future.