Department of Integrated Genetics, National Institute of Genetics, Yata 1111, Mishima 411-8540, Shizuoka, Japan.
Curr Opin Plant Biol. 2011 Feb;14(1):81-7. doi: 10.1016/j.pbi.2010.08.017. Epub 2010 Sep 23.
Transposable elements (TEs) and repeats are methylated and silenced epigenetically in a variety of organisms including plants. Recent results in Arabidopsis suggest that the TE silencing can be reprogrammed by small RNA during gametogenesis. On the other hand, TE-specific DNA methylation independent of small RNA can be induced by H3K9 methylation through mechanisms conserved between plants and fungi. Methylation of CG sites is found not only in TEs but also in the body of constitutively transcribed genes. Although the function of gene-body methylation is still elusive, the distribution and control of this type of DNA methylation are very similar between plants and animals. Possible interactions of these multiple layers of epigenetic marks and their evolution are discussed.
转座元件 (TEs) 和重复序列在多种生物体中（包括植物）通过表观遗传被甲基化和沉默。最近在拟南芥中的研究结果表明，在配子发生过程中小 RNA 可以重新编程 TE 的沉默。另一方面，通过植物和真菌之间保守的机制，H3K9 甲基化可以诱导与小 RNA 无关的 TE 特异性 DNA 甲基化。CG 位点的甲基化不仅存在于 TEs 中，也存在于组成型转录基因的基因体中。尽管基因体甲基化的功能仍然难以捉摸，但这种类型的 DNA 甲基化在植物和动物之间的分布和控制非常相似。讨论了这些多层表观遗传标记的相互作用及其进化。
