重金属镉、铅对多年生黑麦草细胞内几种抗氧化酶基因表达的影响

Effect of Cadmium Ion and Lead Ion Induced Stress on Anti-oxidative Genes Expression in Perennial Ryegrass Cells

重金属胁迫作为逆境条件之一对植物抗逆境代谢基因表达影响状况是筛选污染环境治理时草被植物的主要依据。本文利用Northern印记杂交技术,对重金属离子处理后多年生黑麦草幼苗内的几种抗氧化酶基因表达的ploy(A)+mRNA进行分析。初步研究结果表明,镉、铅离子胁迫处理对幼苗根系内超氧化物酶基因(Mn-sod)、过氧化氢酶基因(Cat)、抗坏血酸过氧化物酶基因(Apx)、谷胱甘肽过氧化物酶基因(Gpx)的表达产生不同影响,这与上述基因编码的相应代谢酶在抗逆代谢中的作用有一定关系。由于镉离子胁迫时产生的活性氧物质远大于铅离子胁迫,不同离子处理后上述基因表达情况出现一些差异。其中,Mn-sod在镉胁迫4h内被快速诱导、而铅胁迫后12h该基因表达量才达到相近的表达强度;Cat表达量在镉胁迫8h后达到较高值且持续增加,而铅胁迫后12h内仍然较低,24h时达到与镉胁迫相近的表达强度;两种金属离子对Gpx表达的影响相似,但镉离子诱导的基因表达强度要远大于铅离子;铅离子胁迫4h后Apx表达强度开始持续增加,但镉胁迫对Apx表达影响可能因试验误差造成降低的结果(有必要做进一步重复研究)。可见,重金属胁迫与其他逆境胁迫一样对植物逆境适应代谢,以及相关基因的表达均产生积极影响,在植物抗逆代谢研究中应该引起足够重视。

Heavy metal ion-induced stress is one of adverse conditions to plant grown, Cadmium （Cd） and Lead （Pb） are among the most toxic of industrial pollutions. When the heavy metal is accumulated in soil by heavy metal pollutant, it will enter into plant and will badly menace agricultural products. Anti-oxidative enzyme is the most important metabolism enzyme in cells which metabolism and catabolism reactive oxygen species （ROS） in cells induced by adverse condition stress. The expression of the anti-oxidative enzyme gene will be affected by ROS. So, the state of some anti-oxidative enzymes genes expression affected by heavy metal ion-induced stress is important reference factor of selecting some tolerate plant. Using comparison between RNA blot, the paper analyzed the expression of Mn-sod（manganese-containing superoxide dismutase gene）, Cat （catalase gene）, Gpx （gluthation peroxidase gene） and Apx （ascorbate peroxidase gene） by heavy metal-induced, in perennial ryegrass （Lolium perenne） exposed to heavy metal ion-induced stress for 0-24 h. Because of the influence upon the perennial ryegrass cell genes expression induced by both of metal ions is different, cadmium ion stress caused more intense oxidation stress to cell metabolism than lead ion stress, and the enzymes genes expression have been induced by this stresses is different, too. Northern blot analyses showed that the transcription of 4 genes is induced by both of ion-induced oxidative stress. In continuous cultures, the expression of Mn-sod is strongly stimulated upon increased to both metal ions within 4 h after stress treatment. Mn-sod transcript level is continued to increase until 24 h. But, the gene expressional intensity induced by cadmium stress is more than that induced by lead stress in same time. Cat transcript level began increased after stress 8 h and remained at elevated levels until 24 h. Gpx and Apx transcript level is not alike deal with different metal ions. The effect of cadmium ion-induced stress on the gene expressional intensity is more than that of lead ion-induced stress, too.