Epigenetic reprogramming occurs during gametogenesis as well as during embryogenesis to reset the genome for early development. In flowering plants, many heterochromatic marks are maintained in sperm, but asymmetric DNA methylation is mostly lost. Asymmetric DNA methylation is dependent on small RNA but the re-establishment of silencing in embryo is not well understood. Here we demonstrate that small RNAs direct the histone H3 lysine 9 dimethylation during Arabidopsis thaliana embryonic development, together with asymmetric DNA methylation. This de novo silencing mechanism depends on the catalytic domain of SUVH9, a Su(Var)3-9 homolog thought to be catalytically inactive.

中文翻译：

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小 RNA 指导拟南芥胚胎中的组蛋白甲基化

表观遗传重编程发生在配子发生期间以及胚胎发生期间，以重置基因组以进行早期发育。在开花植物中，精子中保留了许多异色标记，但大部分不对称 DNA 甲基化已丢失。不对称 DNA 甲基化依赖于小 RNA，但在胚胎中重新建立沉默尚不清楚。在这里，我们证明了小 RNA 在拟南芥胚胎发育过程中指导组蛋白 H3 赖氨酸 9 甲基化，以及不对称 DNA 甲基化。这种从头沉默机制取决于 SUVH9 的催化域，这是一种被认为无催化活性的 Su(Var)3-9 同系物。