过量表达GST基因对盐胁迫下转基因拟南芥氧化损伤的影响

Effects of GST Gene Over-expression on Oxidative Damage to Transgenic Arabidopsis under Salt Stress

利用模式生物拟南芥作为实验材料,通过测定谷胱甘肽-抗坏血酸代谢相关酶(GST、GPX、APX、GR、DHAR、MDHAR)的活性和GSH、ASA、MDA含量以及生物量等来研究过量表达具有过氧化物酶活性的盐地碱蓬谷胱甘肽转移酶基因(GST基因)对盐胁迫下转基因拟南芥氧化损伤的影响.结果显示,转基因拟南芥比野生型具有较高的GST、GPX以及MDHAR酶活性;前者还具有较多的还原型谷胱甘肽和抗坏血酸,并且谷胱甘肽库氧化水平较野生型高.盐胁迫不但部分抑制了野生型拟南芥的生长,同时也导致了大量脂质过氧化物的积累;而盐胁迫对转基因拟南芥的生长抑制不明显,也没有较多的脂质过氧化物的积累.结果表明,过量表达盐地碱蓬谷胱甘肽转移酶基因提高了转基因拟南芥依赖于还原型谷胱甘肽的过氧化物清除途径,同时有可能改变了GSH和ASA的代谢途径,这两方面的作用导致了转基因拟南芥氧化损伤的降低,使转基因拟南芥在盐胁迫下保持较好的生长态势.

The activities of the enzymes related to glutathione-ascorbic acid metabolism（ GST, GPX, APX, GR,DHAR,MDHAR）,the contents of GSH,ASA and MDA and the biomass of Arabidopsis,a modular organism,were measured to study the effects of the over-expression of GST gene of Suaeda salsa showing peroxidase activity on oxidative damage to transgenic Arabidopsis. It was shown that transgenic Arabidopsis had higher activities of GST,GPX and MDHAR than its wild type;the former contained more glutathione and ascorbate than the latter and the glutathione pool of the former was more oxidized than the wild type. Salt stress not only inhibited the growth of wild Arabidopsis type and resulted in the accumulation of great amounts of lipid peroxides;but salt stress did not obviously inhibit the growth of transgenic Arabidopsis and did not result in the accumulation of great amounts of peroxides. Results showed that the overexpression of GST gene of Suaeda salsa enhanced the reliance of transgenic Arabidopsis on the peroxideclearing pathway of glutathione and probably changed the metabolic pathway of GSH and ASA and these two effects led to the reduction of oxidative damage to Arabidopsis so as to make transgenic Arabidopsis grow well under salt stress.