外源NO对转基因白桦外源基因表达及DNA甲基化的影响

Effects of Exogenous Nitric Oxide on Exogenous Gene Expression and DNA Methylation in Transgenic Birch

为探讨外源NO诱导转基因白桦外源基因表达与基因组DNA甲基化之间的关系,本研究分析了NO供体硝普钠(sodium nitroprusside,SNP)对转基因白桦愈伤组织中外源基因BGT转录的影响,并对此过程中基因组DNA甲基化水平、甲基转移酶基因DRM、MET表达量及生理生化指标进行研究。结果表明:2 mmol·L^(-1)SNP处理后,转基因白桦防御酶活性、丙二醛(MDA)含量显著升高,表明高浓度NO对白桦细胞正常生命活动产生了伤害;甲基转移酶DRM和MET基因上调表达,基因组DNA甲基化水平由10.6%增加到16.5%,外源基因BGT表达量在6 h时显著增加,3 d时仅为对照的0.46倍,说明转基因白桦外源BGT基因的表达对高浓度NO响应明显且受基因组甲基化水平的影响。本研究揭示了转基因白桦外源BGT基因和甲基转移酶MET、DRM基因对高浓度NO的响应模式,分析了基因组甲基化水平及生理生化特征的变化,为转基因植物生长发育的表观遗传调控和外源基因表达影响机制的研究奠定基础。

In order to investigate the relationship between transgene expression and the methylation of genomic DNA induced by 2 mmol~ L-1 SNP in Transgenic birch, the effect of SNP （sodium nitroprusside） on the expression of exogenous BGT, methyhransferase gene DRM, MET and the level of DNA methylation were determined in transgenic birch callus. The activities of defense enzymes and the MDA （malondialdehyde） content in transgenic birch were increased significantly, which indicated high concentration of NO had harm on the normal life of birch cells. The methyltransferase DRM and MET genes were up-regulated and the methylation level of genomic DNA was increased from 10.6% to 16.5%. The transcription level of BGT was improved at 6 h and only 0.46 folds of the control at 3 d, which suggested the expression of exogenous BGT gene in transgenic brich was affected by high concentration of NO and the level of genomic methylation. The results revealed the response patterns of exogenous gene and methyltransferase gene and determined the genomic methylation level and physiological and biochemical characteristics to the high concentration of NO in birch, which will provide some references for further study of epigenetic regulation and regulation of exogenous gene expression in transgenic plants.