【摘要】 以拟南芥(Arabidopsis thaliana)为材料,研究二氧化硫(SO2)熏气对植株硫同化作用的影响.结果显示,SO2熏气后,拟南芥植株地上组织中硫同化关键酶半胱氨酸合成酶(OAS-TL)活性提高,半胱氨酸(Cys)和谷胱甘肽(GSH)含量显著增加,谷胱甘肽硫转移酶(GST)和谷胱甘肽过氧化物酶(GSH-PX)的活性诱导性增高;GSH-PX、GST和硫氧还蛋白等多种与逆境生理关系密切的基因表达上调.结果表明,SO2胁迫能诱导拟南芥植株硫同化作用增强,使Cys和GSH水平提高,促进相关防御酶活性及基因表达水平升高,以有效清除植物细胞中的活性氧和其它胞内有毒代谢物,提高植株对逆境的适应性.更多还原

【Abstract】 The response of sulfur assimilation process to sulfur dioxide (SO 2) was investigated in SO 2-fumigatited Arabidopsis thaliana (L.).Four-week-old plants were exposed to 0,2.5,10 and 30 mg m-3 of SO 2 for 120 h,respectively.The activity of cysteine synthase [O-acetylserine(thiol) lyase,OAS-TL],a key enzyme of sulfur assimilation,increased significantly in A.thaliana shoots after exposure to SO 2.Meanwhile,Cys content enhanced markedly with increasing OAS-TL activity.Our results demonstrated an enhancement of sulfur assimilation in SO 2-fumigated A.thaliana plants.Moreover,GSH level and GSH-related enzymes activities increased significantly and maintained higher levels during SO 2 fumigation.The activities of glutathione peroxidase (GSH-PX) and glutathione S-transferase (GST) enhanced with increasing SO 2 concentration and exposure time.By using Affymetrix ATH1 GeneChip,a genomic-wide gene expression was investigated in A.thaliana plants exposed to 30 mg m-3 SO 2 for 72 h.Analyses of gene expression profile indicated that some stress response genes including GSH-PXs,GSTs and thioredoxin (TRXs) were strongly up-regulated in SO 2-fumigated A.thaliana shoots.The increases in mRNA levels of GSTU3 and TRXh8 in response to SO 2 fumigation were confirmed by the results of semi-quantitative RTPCR.Our results indicated that high concentration of SO 2 could enhance sulfur assimilation process and cause Cys and GSH contents increase in plant cells.The enhancement of GSH content and GSH-related defense enzymes activities might mediate plant adaption to SOstress.更多还原