Rop GTPase Signaling Networks: Roles in Development and Stress Responses

在真核生物中，羊鸟嘌呤核苷酸结合蛋白（G蛋白）是控制胞外信号向胞内信号转导途径流动的通用分子开关。拟南芥具有一个独特的小G蛋白亚家族，称为Rop。在拟南芥中，Rop调控许多信号转导通路。本研究的重点是控制叶表皮铺装细胞形态发生的一种依赖于rop的途径。由于植物细胞被包裹在细胞壁中，不具有运动性，因此细胞形态发生对植物的生长发育尤为重要。表皮铺装细胞具有独特的叶状和窦状互锁的细胞形态，为研究植物细胞形态发生机制提供了一个有益的模型系统。先前利用转基因表达Rop2显性突变基因的研究表明，一个或多个Rops控制着叶片的形成。然而，这些研究并没有揭示11种拟南芥gtpase中哪一种参与了控制路面细胞形态发生的信号通路。此外，这一途径的其他成分是未知的。作为阐明拟南芥细胞形态发生的分子机制这一长期目标的第一步，这项工作包含两个主要目的。首先，拟南芥Rop基因的敲除突变体将用于确定哪个Rop基因控制叶片铺装细胞的形态发生。其次，将使用酵母双杂交方法和高通量蛋白质组学方法来鉴定rop依赖性形态发生途径的组成部分。该研究计划有望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基因操纵有利于农业和园艺实践的植物形态是有用的。

0115078YangGuanine nucleotide-binding proteins (G proteins) are universal molecular switches that control the flow of extracellular signals to intracellular signal transduction pathways in eukaryotic organisms. Arabidopsis possesses a unique subfamily of small G proteins, termed Rop. Rop regulates many signal transduction pathways in Arabidopsis. This proposed research is focused on a Rop-dependent pathway that controls the morphogenesis of leaf epidermal pavement cells. Because plant cells are encased in cell walls and are non-motile, cell morphogenesis is particularly important for plant growth and development. Having a unique cell shape with interlocking lobes and sinuses, epidermal pavement cells provide a useful model system for studying the mechanism of cell morphogenesis in plants. Previous studies using transgenic expression of Rop2 dominant mutant genes suggest that one or more Rops controls the formation of lobes. However, these studies did not reveal which of the 11 Arabidopsis Rop GTPases participate in the signaling pathway that controls the morphogenesis of pavement cells. Furthermore, other components in this pathway are unknown. As a first step in the long-term goal of elucidating the molecular mechanism of cell morphogenesis in Arabidopsis, this proposed work contains two major aims. First, knockout mutants for Arabidopsis Rop genes will be used to determine which Rop gene(s) controls the morphogenesis of leaf pavement cells. Second, components of the Rop-dependent morphogenesis pathway will be identified using the yeast two-hybrid method complemented with a high throughput proteomics approach. This research plan is expected 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.