Key message

Recent understandings ofArabidopsiszygote.

Abstract

Body axis formation is essential for the proper development of multicellular organisms. The apical-basal axis in Arabidopsis thaliana is determined by the asymmetric division of the zygote, following its cellular polarization. However, the regulatory mechanism of zygote polarization is unclear due to technical issues. The zygote is located deep in the seed (ovule) in flowers, which prevents the living dynamics of zygotes from being observed. In addition, elucidation of molecular pathways by conventional forward genetic screens was not enough because of high gene redundancy in early development. Here, we present a review introducing two new methods, which have been developed to overcome these problems. Method 1: the two-photon live-cell imaging method provides a new system to visualize the dynamics of intracellular structures in Arabidopsis zygotes, such as cytoskeletons and vacuoles. Microtubules form transverse rings and control zygote elongation, while vacuoles dynamically change their shapes along longitudinal actin filaments and support polar nuclear migration. Method 2: the transcriptome method uses isolated Arabidopsis zygotes and egg cells to reveal the gene expression profiles before and after fertilization. This approach revealed that de novo transcription occurs extensively and immediately after fertilization. Moreover, inhibition of the de novo transcription was shown to sufficiently block the zygotic division, thus indicating a strong possibility that yet unidentified zygote regulators can be found using this transcriptome approach. These new strategies in Arabidopsis will help to further our understanding of the fundamental principles regarding the proper formation of plant bodies from unicellular zygotes.

中文翻译：

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植物合子中的细胞内动力学和转录调控：拟南芥的案例研究。

关键信息

对拟南芥合子的最新认识。

抽象

体轴形成对于多细胞生物的正常发育至关重要。拟南芥的顶基轴由合子的不对称分裂，取决于其细胞极化。但是，由于技术问题，合子极化的调节机制尚不清楚。合子位于花的种子（胚珠）的深处，这阻止了观察到合子的动态。另外，由于早期开发中的高基因冗余性，通过常规的正向遗传筛选来阐明分子途径还不够。在这里，我们提出了一个综述，介绍了两种新方法，这些新方法已经开发出来，可以克服这些问题。方法1：双光子活细胞成像方法提供了一个新的系统来可视化拟南芥细胞内结构的动力学受精卵，例如细胞骨架和液泡。微管形成横向环并控制合子伸长，而液泡沿纵向肌动蛋白丝动态改变其形状并支持极性核迁移。方法2：转录组方法使用分离的拟南芥合子和卵细胞揭示受精前后的基因表达谱。这种方法表明，从头转录广泛发生在受精后。此外，显示出从头转录的抑制作用可充分阻断合子分裂，从而表明使用该转录组方法仍可发现尚未鉴定的合子调节子的可能性很大。拟南芥中的这些新策略 有助于我们进一步了解有关从单细胞合子正确形成植物体的基本原理。