Signaling to Cell Morphogenesis in Arabidopsis Leaves

这个项目的长期目标是了解植物细胞是如何实现各种形状的。细胞形状的形成对植物的发育和形态发生很重要，但这一基本过程背后的分子机制却知之甚少。本项目的重点是控制拟南芥叶上皮细胞连锁拼图外观的调控蛋白网络。这个网络中的一个核心角色是一种植物特有的鸟嘌呤核苷酸结合蛋白，即ROP。拼图形态的形成需要细胞叶形成区的局部细胞突起与其他区域突起的局部约束相协调。ROP通过激活RIC4蛋白来组装局部细胞生长所需的肌动蛋白细胞骨架，以及通过失活组织微管细胞骨架以限制细胞生长的RIC1蛋白来促进分叶。RIC1通路反馈抑制了ROP的激活，以确保凹陷的形成。在这项拟议的工作中，将使用遗传学、分子、细胞生物学和蛋白质组学方法来阐明ROP活性调控的机制以及RIC1对微管的调控机制。本研究的目的是对植物细胞形态形成的机制提供新的见解，并发现控制细胞形态发生和植物发育的新基因。这些基因可能被证明对对农业和园艺实践有利的植物形态的遗传操作有用。该项目还将通过少数民族学生暑期研究实习和REU计划等外联方案，将研究与本科生和研究生的培训以及代表不足的本科生的参与结合起来。

The long-term goal of this project is to understand how plant cells achieve various shapes. Cell shape formation is important for the development and the morphogenesis of plants, but the molecular mechanism underlying this fundamental process is poorly understood. This project focuses on a network of regulatory proteins in the control of interlocking jigsaw puzzle appearance of Arabidopsis leaf epidermal cells. A central player in this network is a plant-specific guanine nucleotide binding protein known as ROP. The formation of jigsaw puzzle appearance requires the coordination of localized cellular outgrowth in the lobe-forming region of the cell with localized constraint of outgrowth in the other regions. ROP promotes lobing by activating the RIC4 protein to assemble the actin cytoskeleton required for localized cell outgrowth, as well as by inactivating the RIC1 protein that organizes the microtubule cytoskeleton for constraining cellular outgrowth. The RIC1 pathway feedback represses ROP activation to assure the formation of indentations. In this proposed work, genetic, molecular, cell biological, and proteomic approaches will be used to elucidate the mechanism by which ROP activity is regulated as well as the mechanism underpinning the RIC1 regulation of microtubules. This research aim is expected to provide new insights into the mechanism for cell shape formation in plants and to identify new genes that control cell morphogenesis and plant development. These genes may prove to be useful for genetically manipulating plant forms that are beneficial to agricultural and horticultural practices. This project will also integrate research with training of undergraduate and graduate students and participation of underrepresented undergraduate students through outreach programs such as Minority Student Summer Research Internships and REU Programs.