Epigenetic marks are reprogrammed in the gametes to reset genomic potential in the next generation. In mammals, paternal chromatin is extensively reprogrammed through the global erasure of DNA methylation and the exchange of histones with protamines1,2. Precisely how the paternal epigenome is reprogrammed in flowering plants has remained unclear since DNA is not demethylated and histones are retained in sperm3,4. Here, we describe a multi-layered mechanism by which H3K27me3 is globally lost from histone-based sperm chromatin in Arabidopsis. This mechanism involves the silencing of H3K27me3 writers, activity of H3K27me3 erasers and deposition of a sperm-specific histone, H3.10 (ref. 5), which we show is immune to lysine 27 methylation. The loss of H3K27me3 facilitates the transcription of genes essential for spermatogenesis and pre-configures sperm with a chromatin state that forecasts gene expression in the next generation. Thus, plants have evolved a specific mechanism to simultaneously differentiate male gametes and reprogram the paternal epigenome.

中文翻译：

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H3K27me3 的靶向重编程可重置植物父本染色质的表观遗传记忆。

表观遗传标记在配子中被重新编程，以重置下一代的基因组潜力。在哺乳动物中，父本染色质通过 DNA 甲基化的整体消除以及组蛋白与鱼精蛋白的交换而被广泛重编程1,2。由于 DNA 没有去甲基化并且组蛋白保留在精子中，因此父系表观基因组在开花植物中如何重新编程仍不清楚3,4。在这里，我们描述了拟南芥中 H3K27me3 从基于组蛋白的精子染色质中全局丢失的多层机制。该机制涉及 H3K27me3 书写器的沉默、H3K27me3 擦除器的活性以及精子特异性组蛋白 H3.10（参考文献 5）的沉积，我们证明它对赖氨酸 27 甲基化免疫。H3K27me3 的缺失促进了精子发生所必需的基因的转录，并用染色质状态预先配置了精子，从而预测了下一代的基因表达。因此，植物进化出了一种特定的机制来同时分化雄性配子并重新编程父本表观基因组。