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

细胞是植物结构的基本构件。由于细胞壁的限制，细胞分裂过程中细胞形状的保持和细胞壁的定位对植物的形态发生至关重要。分裂平面的取向是形成事件的基础，这些事件决定了胚胎和胚胎后发育过程中细胞和组织的多样性。因此，了解这一过程中使用的机制在植物细胞和发育生物学中具有重要意义。在拟南芥胚胎发育过程中，对称细胞分裂中细胞分裂平面的方向由一个基于最小表面积的简单几何缺省规则决定。相比之下，导致新组织层形成的不对称细胞分裂在转录生长素反应上偏离了这一简单规则。对这一现象的进一步分子调控分析揭示了MT相关的IQD蛋白和小Rho GTP酶的信号成分，即ROP。在这个项目中，我将结合遗传学、分子生物学、细胞生物学和计算机成像分析的方法，研究ROP活动如何在胚胎发育过程中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，我将探索与ROP下游信号组件(如MT结合的IQD)的相互作用如何在早期胚胎模式形成过程中调节细胞动力学。该项目的结果将揭示在质膜-细胞骨架界面上的新的信号机制，该机制在植物发育过程中保持细胞形状并定向分裂平面。

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.