Department of Plant Biology, University of California, Davis, CA 95616, USA.
Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA.
Dev Cell. 2017 Nov 6;43(3):349-358.e4. doi: 10.1016/j.devcel.2017.10.005.
The zygotic transition, from a fertilized egg to an embryo, is central to animal and plant reproduction. Animal embryos depend upon maternally provided factors until zygotic genome activation (ZGA). In plants, the timing and parental genome contributions to ZGA are unresolved. Here, we use the flowering plant Oryza sativa (rice) to characterize transcriptomes of time-staged isogenic and hybrid zygotes following fertilization. Large-scale transcriptomic changes were observed in unicellular zygotes, including upregulation of S-phase genes, a characteristic of ZGA. The parental contributions to ZGA were highly asymmetric. Zygotic transcription was primarily from the maternal genome and included genes for basic cellular processes. Transcription of the paternal genome was highly restricted but unexpectedly included genes encoding putative pluripotency factors expressed at the onset of ZGA. Thus, distinct transcriptional activities are exhibited by the parental genomes during the initiation of embryogenesis, which presumptively derive from divergent pre-zygotic transcriptional states established in the gametes.
从受精卵到胚胎的合子转变是动物和植物繁殖的核心。动物胚胎依赖于母体提供的因子，直到合子基因组激活（ZGA）。在植物中，ZGA 的时间和双亲基因组的贡献尚不清楚。在这里，我们使用开花植物水稻（Oryza sativa）来描述受精后同基因和杂种合子的时间分期的转录组。在单细胞合子中观察到大规模的转录组变化，包括 S 期基因的上调，这是 ZGA 的特征。ZGA 的双亲贡献极不对称。合子转录主要来自母本基因组，并包括基本细胞过程的基因。父本基因组的转录受到高度限制，但出人意料的是，它包括编码在 ZGA 开始时表达的潜在多能性因子的基因。因此，在胚胎发生的起始阶段，双亲基因组表现出不同的转录活性，这可能源自配子中建立的不同的合子前转录状态。
