二氧化硫胁迫导致拟南芥防护基因表达改变

研究SO2熏气对拟南芥细胞中mRNA和蛋白质表达的影响,分析植株对逆境胁迫的响应机制.结果表明,30 mg·m-3 SO2 熏气72 h后拟南芥地上组织中差异表达1倍以上的基因有494个,其中抗氧化酶、谷胱甘肽硫转移酶(GST)、硫氧还蛋白等多种与逆境生理关系密切的基因表达上调;2.5～30 mg·m-3 SO2 熏气可导致超氧化物岐化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GPX)和GST的活性诱导性增高,SOD、CAT同工酶谱带特征改变.研究结果表明,SO2 胁迫能够诱导拟南芥中防护基因在mRNA和蛋白质表达水平的改变,这些基因的差异性表达可能对逆境生理过程有益.

Expression of Arabidopsis defense-related genes in response to sulfur dioxide fumigation

Sulfur dioxide (SO2 ) is one of the most common and harmful air pollutants. It results primarily from the combustion of sulfur containing fossil fuels, metallurgical processes involving sulfide ores, the production of sulfuric acid and volcanic activity. Exposure to high concentration of SO2 can induce leaf necrosis, plant growth inhibition and DNA damage in leaves and roots. However, plants adapt to environmental stresses by developing a number of mechanisms for regulation of defense response. Expression of stress responsive gene increases under rapidly changing environmental conditions, which may play important roles in regulating responses to abiotic stresses. To further understanding the adaptive mechanisms of higher plants, effects of SO2 exposure on generation of reactive oxygen species (ROS), mRNA level, isoenzymes characteristics and activities of defense enzymes were investigated in Arabidopsis thaliana (L.). By using oligoneucleotide arrays, a genomic-wide gene expression was investigated in shoots of A. thaliana Col-0. Our experiments found that 494 genes showed more than one fold difference in mRNA levels between SO2 fumigation and the control, and many defense-related genes including antioxidant defense enzymes, glutathione s-transferase (GST) and thioredoxins genes showed enhanced expression after exposure to 30 mg?m-3 SO2 for 72 h. Exposure to SO2 (2.5, 10 and 30 mg?m-3, respectively) increased O-?2 production rate and H2O2 content. Both O-?2 production and H2O2 content rised up with increasing SO2 concentration and prolonged period, demonstrating an accumulation of ROS in A. thaliana leaves. Analysis of differential protein expression carried out by detecting difference in anti-oxidative enzymes activities and the characteristics of superoxide dismutase (SOD) and catalase (CAT) isoenzymes banding patterns between SO2 fumigation and the control. Results of the present study showed that exposure to SO2 (2.5, 10 and 30 mg?m-3, respectively) induced significant increases in activities of SOD, peroxidase (POD), glutathione peroxidase (GPX) and glutathione S-transferase (GST), but decreases in activities of SOD and CAT in A. thaliana leaves exposed to 30 mg?m-3 SO2 for 72 h. Meanwhile both FeSOD and CuZnSOD isoforms increased, along with CAT2 and CAT3 isoforms decreased. Changes in both activities of anti-oxidative enzymes and characteristics of SOD and CAT isoenzyme (bands) demonstrated the differential expression levels of defense proteins in A. thaliana leaves. These results showed that SO2 caused changes in mRNA and protein expression levels of anti-oxidative defense enzymes. In addition, contents of reduced glutathione (GSH) increased significantly in A. thaliana leaves during SO2 fumigation. Our results suggest that defense response genes may have a particular function in plant adaptation to environmental change. Antioxidant therapy may play a major role in preventing SO2 damage in plant cells.