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

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.