Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras, 2780-156, Portugal.
Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, Oeiras, 2780-157, Portugal.
Plant J. 2020 Aug;103(4):1289-1303. doi: 10.1111/tpj.14801. Epub 2020 Jul 3.
In flowering plants, pollen development is under a dynamic and well-orchestrated transcriptional control, characterized by an early phase with high transcript diversity and a late post-mitotic phase skewed to a cell-type-specific transcriptome. Such transcriptional changes require a balance between synthesis and degradation of mRNA transcripts, the latter being initiated by deadenylation. The CCR4-NOT complex is the main evolutionary conserved deadenylase complex in eukaryotes, and its function is essential during germline specification in animals. We hypothesized that the CCR4-NOT complex might play a central role in mRNA turnover during microgametogenesis in Arabidopsis. Disruption of NOT1 gene, which encodes the scaffold protein of the CCR4-NOT complex, showed abnormal seed set. Genetic analysis failed to recover homozygous progeny, and reciprocal crosses confirmed reduced transmission through the male and female gametophytes. Concordantly, not1 embryo sacs showed delayed development and defects in embryogenesis. not1 pollen grains exhibited abnormal male germ unit configurations and failed to germinate. Transcriptome analysis of pollen from not1/+ mutants revealed that lack of NOT1 leads to an extensive transcriptional deregulation during microgametogenesis. Therefore, our work establishes NOT1 as an important player during gametophyte development in Arabidopsis.
在开花植物中，花粉发育受到动态且协调良好的转录控制，其特征是早期具有高转录多样性，后期有丝分裂后阶段偏向于细胞类型特异性转录组。这种转录变化需要 mRNA 转录物的合成和降解之间的平衡，后者由脱腺苷酸化引发。CCR4-NOT 复合物是真核生物中主要的进化保守脱腺苷酸酶复合物，其功能在动物生殖系特化过程中至关重要。我们假设 CCR4-NOT 复合物可能在拟南芥小配子发生过程中的 mRNA 周转中发挥核心作用。破坏编码 CCR4-NOT 复合物支架蛋白的 NOT1 基因显示出异常的种子设置。遗传分析未能恢复纯合后代，并且正反交证实了通过雄性和雌性配子体的减少传递。一致地，not1 胚囊显示出发育延迟和胚胎发生缺陷。not1 花粉粒表现出异常的雄性生殖单位构型并且不能发芽。来自 not1/+ 突变体的花粉的转录组分析表明，缺乏 NOT1 导致小配子发生过程中的广泛转录失调。因此，我们的工作确立了 NOT1 作为拟南芥配子体发育过程中的重要参与者。
