DNA methylation is reconfigured at the onset of reproduction in rice shoot apical meristem
DNA methylation is reconfigured at the onset of reproduction in rice shoot apical meristem
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DOI：
10.1038/s41467-020-17963-2
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发表时间：
2020-08-14
影响因子：
16.6
通讯作者：
Tsuji, Hiroyuki
中科院分区：
文献类型：
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作者：
Higo, Asuka;Saihara, Noriko;Tsuji, Hiroyuki
DNA甲基化是一种表观遗传修饰，它规定了多能干细胞的基本状态，并调节了干细胞向各种细胞类型的发育转变。在开花植物中，茎尖分生组织（shoot apical meriorganization， SAM）包含一个多能干细胞群体，它产生植物的地上部分，包括生殖细胞。在适当的条件下，SAM经历了从叶片形成的营养SAM到花序和花形成的生殖SAM的发育转变。虽然SAM特征在这一转变中很大程度上发生了变化，但DNA甲基化的全貌仍然难以捉摸。通过分析营养和生殖阶段分离的水稻SAM的全基因组DNA甲基化，研究人员发现，相对于分化叶片，营养SAM中CHH位点的甲基化保持较高，特别是转座元件（TEs），并且通过rna依赖的DNA甲基化途径在生殖SAM中增加。我们还发现，配子中高度甲基化的te中有一半已经在SAM中发生了CHH超甲基化。我们的研究结果表明，早在生殖细胞分化之前，DNA甲基化就开始在SAM中发生变化，以保护基因组免受有害te的侵害。开花植物的茎尖分生组织由形成叶片过渡到花器官。在这里，Higo等人表明，许多在配子中高度甲基化的转座子的DNA甲基化在开花之前就在SAM中建立了，这表明它在生殖细胞分化之前很久就保护了有害的转座子。
DNA methylation is an epigenetic modification that specifies the basic state of pluripotent stem cells and regulates the developmental transition from stem cells to various cell types. In flowering plants, the shoot apical meristem (SAM) contains a pluripotent stem cell population which generates the aerial part of plants including the germ cells. Under appropriate conditions, the SAM undergoes a developmental transition from a leaf-forming vegetative SAM to an inflorescence- and flower-forming reproductive SAM. While SAM characteristics are largely altered in this transition, the complete picture of DNA methylation remains elusive. Here, by analyzing whole-genome DNA methylation of isolated rice SAMs in the vegetative and reproductive stages, we show that methylation at CHH sites is kept high, particularly at transposable elements (TEs), in the vegetative SAM relative to the differentiated leaf, and increases in the reproductive SAM via the RNA-dependent DNA methylation pathway. We also show that half of the TEs that were highly methylated in gametes had already undergone CHH hypermethylation in the SAM. Our results indicate that changes in DNA methylation begin in the SAM long before germ cell differentiation to protect the genome from harmful TEs. The shoot apical meristem of flowering plants transitions from forming leaves to floral organs. Here Higo et al. show that DNA methylation of many transposons that are hypermethylated in gametes is established in the SAM before flowering, suggesting it protects against harmful transposition long before germ cell differentiation.