背景回顾：Establishing the embryonic body plan of multicellular organisms relies on precisely orchestrated cell divisions coupled with pattern formation, which, in animals, are regulated by Polycomb group (PcG) proteins. The conserved Polycomb Repressive Complex 2 (PRC2) mediates H3K27 trimethylation and comes in different flavors in Arabidopsis. 

提出问题：The PRC2 catalytic subunit MEDEA is required for seed development; however, a role for PRC2 in embryonic patterning has been dismissed. 

主要发现：Here, we demonstrate that embryos derived from medea eggs abort because MEDEA is required for patterning and cell lineage determination in the early embryo. 

作用机制：Similar to PcG proteins in mammals, MEDEA regulates embryonic patterning and growth by controlling cell-cycle progression through repression of CYCD1;1, which encodes a core cell-cycle component. 

结论：Thus, Arabidopsis embryogenesis is epigenetically regulated by PcG proteins, revealing that the PRC2-dependent modulation of cell-cycle progression was independently recruited to control embryonic cell proliferation and patterning in animals and plants.

 摘 要 

多细胞生物建立胚胎体轴依赖于细胞分裂与模式形成之间的精确协调，在动物中，这一过程受到Polycomb group（PcG）蛋白的调控。保守的多梳抑制复合物PRC2介导H3K27三甲基化，而在拟南芥中PRC2具有不同类型的复合物。PRC2催化亚基MEDEA是种子发育所必需的；然而，PRC2在胚胎形成中的作用还不清楚。本文中，作者发现由medea突变体卵细胞发育而来的胚胎会败育，因为MEDEA是早期胚胎中模式形成和细胞谱系决定所必需的。与哺乳动物中的PcG蛋白类似，MEDEA通过抑制编码细胞周期核心成分的基因CYCD1;1来控制细胞周期进程，从而调控胚胎的模式建成和生长。因此，拟南芥胚胎发生受到PcG蛋白介导的表观遗传调控，说明动物和植物中，PRC2依赖性的细胞周期进程调控是被独立招募来控制胚胎细胞增殖和模式形成的。

 通讯作者 

** Ueli Grossniklaus **