二氧化硫胁迫诱导拟南芥NIT2基因DNA甲基化修饰  

Sulfur Dioxide Induces DNA Methylation Alteration of A Gene Encoding Nitrilase 2 Protein in Arabidopsis Plants

作　　者：李利红[1,2] 仪慧兰[1] 王艺雯[1] 杨波[1] 

机构地区：[1]山西大学生命科学学院,环境科学与工程研究中心,太原030006 [2]山西省水产科学研究所,太原030006

出　　处：《农业环境科学学报》2012年第4期685-690,共6页Journal of Agro-Environment Science

基　　金：国家自然科学基金项目(30870454;30470318);高等学校博士学科点专项科研基金(20070108007)

摘　　要：DNA甲基化是一种重要的表观遗传修饰形式。利用亚硫酸氢盐修饰后测序法和甲基化敏感性限制性内切酶-PCR(MSRE-PCR)法,研究SO2胁迫对拟南芥腈水解酶(NIT2)基因序列中胞嘧啶甲基化状态的影响,分析甲基化特征改变在植物胁迫应答过程中的作用。研究发现,30 mg.m-3的SO2连续熏气3 d后,拟南芥植株地上组织细胞中NIT2基因启动子区域CG和CHH(H为C,A或T)位点甲基化水平下降,总甲基化水平降低,但未检出编码区5′端目的片段中CCGG位点甲基化状态的改变。RT-PCR分析表明,SO2胁迫组拟南芥植株地上组织细胞中NIT2基因的转录水平高于对照组。研究结果表明,SO2胁迫导致拟南芥NIT2基因启动子区甲基化水平降低,NIT2基因转录上调,说明SO2胁迫能诱发拟南芥基因胞嘧啶甲基化水平改变,启动子区甲基化水平的降低可能与防御基因的诱导表达有关,胞嘧啶甲基化修饰参与了植物的抗逆生理过程。DNA methylation is involved in the regulation of many cellular processes.Environmental stimuli induce DNA methylation alterations which may have important consequences for plant adaptations.In this study,SO2-induced DNA methylation alteration of a gene encoding nitrilase 2 protein（NIT2） in Arabidopsis was investigated by using bisulfite sequencing and methylation sensitive restriction enzyme PCR.Quantitative analysis of DNA methylation in NIT2 promoter region showed that cytosine residues were hypomethylated in both CG and CHH（where H is C,A or T） contexts after plant exposed to 30 mg·m-3 SO2 for 3 d,and the methylation levels of the promoter decreased from 37% to 32%.However,cytosine methylation change in the sequence CCGG in the upstream part of NIT2 coding region could not be detected in SO2-exposed plants.RT-PCR analysis indicated that NIT2 transcript level increased markedly in plants exposed to 30 mg·m-3 SO2 for 3 d.The present results showed that DNA hypomethylation of NIT2 promoter region was associated with high NIT2 transcript level in SO2-exposed plants.Our results were consistent with the previous report that NIT2 was overexpressed in an Arabidopsis mutant deficient in DNA methyltransferase,indicating that NIT2 expression was directly regulated by promoter DNA methylation.These data suggest that SO2-induced epigenetic change may be closely related to the gene activation in plant response to SO2 stress.Our report may help to reveal a possible role of this epigenetic mechanism in plants adaptation to environmental stress.

关 键 词：SO2 拟南芥 NIT2 DNA甲基化 基因表达 

分 类 号：X503.233[环境科学与工程—环境工程]