DNA胞嘧啶甲基化变异调控植物基因组内功能基因表达和转座子转座活性，影响植物生长和发育的稳定性。 RNA⁃dependent RNA polymerase 2（ RDR2）基因参与RNA⁃directed DNA methylation（ RdDM）途径指导合成CHH（ H＝G、T、A）甲基化，CHH甲基化在基因和转座子上表现不同，是目前DNA胞嘧啶甲基化的研究热点之一。拟南芥中RDR1基因与RDR2属于同一家族，最新研究结果证实，RDR1基因不仅可以指导CHH甲基化形成，并且其功能缺失会不同程度影响CG和CHG甲基化。前期研究工作表明，水稻中其同源基因OsRDR1功能缺失可在特异位点影响DNA胞嘧啶甲基化，但是否大规模影响全基因组DNA甲基化尚不明确。在此基础上，采用甲基化敏感多态性扩增（Methylation sensitive amplification polymorphism，MSAP）技术研究OsRDR1基因功能缺失突变体全基因组CCGG位点的甲基化情况。结果同野生型比较分析发现，OsRDR1基因功能缺失没有引起全基因组CCGG位点甲基化水平的显著变化，但一定程度产生CHG去甲基化变异。由于MSAP试验方法的局限性，关于Osrdr1突变体全基因组DNA胞嘧啶甲基化变异还需更深入研究论证。%DNA cytosine methylation plays an important role in regulating functional gene expression and activity of transposable elements( TEs) , which impacts the stability of plant growth and develop⁃ment. RNA⁃dependent RNA polymerase 2(RDR2)was involved in RNA⁃directed DNA methylation ( RdDM) on CHH methylation ( H=G、T、A) , which had different functions on gene and TEs. RDR1 and RDR2 belonged to the same family in Arabidopsis,and the new researches confirmed that CG/CHG/CHH methylation variation was induced by functional loss of RDR1 gene. In our previous study, we found DNA methylation alteration with a locus specific manner by functional loss of OsRDR1 gene in rice. In this study, we used Methylation Sensitive Amplification Polymorphism ( MSAP ) to detect genome⁃wide CCGG sites⁃methylation in OsRDR1 mutant. The results showed level of genome⁃wide CCGG sites⁃methylation did not change a lot by comparison with wide type, but there was CHH hypo⁃methylation in contrast to wide type. Because of the limitation of MSAP methods, the research of DNA cytosine methylation variation in Osrdr1 mutant needs further study.
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