The role of ROP signaling in auxin-dependent oriented cell division

细胞是植物结构的基本组成部分。由于细胞壁的限制，细胞分裂过程中细胞形状的维持和细胞壁的定位对植物的形态发生至关重要。分裂面取向是胚胎和胚胎后发育过程中决定细胞和组织多样性的形成事件的基础。因此，了解在这一过程中所采用的机制在植物细胞和发育生物学中至关重要。在拟南芥胚胎发生过程中，细胞对称分裂平面的方向是由基于最小表面积的简单几何默认规则决定的。相反，导致新组织层形成的不对称细胞分裂偏离了转录生长素反应的这一简单规则。对这一现象的分子调控的进一步分析揭示了mt相关的IQD蛋白和小Rho gtpase的信号成分，即ROPs。在这个项目中，我将结合遗传学、分子生物学、细胞生物学和计算成像分析等方法，研究胚胎发育过程中ROP活性如何调节细胞形状和分裂平面方向。我将研究这是否涉及质膜极性和细胞骨架组织的调节，以及这些过程如何与定向细胞分裂相关。此外，我将探讨在早期胚胎模式形成过程中，与ROP下游信号成分（如mt结合iqd）的相互作用如何调节细胞动力学。该项目的结果将揭示在植物发育过程中维持细胞形状和定向分裂平面的质膜-细胞骨架界面上的新信号机制。

Cells are fundamental building blocks of plant architecture. Cell shape maintenance and positioning of the wall during cell division are crucial for plant morphogenesis because of cell wall constraints. Orientation of division plane forms the basis for formative events, which determine the cell and tissue diversity during embryonic and post-embryonic development. Thus, understanding the mechanisms employed in this process is of central importance in plant cell and developmental biology. During Arabidopsis embryogenesis the orientation of the cell division plane in symmetric cell divisions is determined by a simple geometric default rule based on minimal surface area. By contrast, asymmetric cell divisions, which result in the formation of new tissue layers, deviate from this simple rule upon transcriptional auxin response. Further analysis on the molecular regulation of this phenomenon revealed MT-associated IQD proteins and signalling components of the small Rho GTPases, namely ROPs. In this project, I will use a combination of approaches involving genetics, molecular biology, cell biology and computational imaging analysis, to address how ROP activity regulates cell shape and division plane orientation during embryo development. I will investigate whether this involves regulation of plasma membrane polarity and cytoskeleton organization, and how these processes correlate with oriented cell division. Furthermore, I will explore how the interaction with ROP downstream signalling components like MT-binding IQDs regulate cell dynamics during early embryo patterning. The outcomes of this project will reveal novel signalling mechanisms at the plasma membrane-cytoskeleton interface that maintain cell shape and orient division planes during plant development.