Control of Plant Cell Shape by the ASB Loci in Arabidopsis

植物细胞形态在植物细胞功能中起着至关重要的作用。由于这种关系，了解植物细胞形状是如何被控制的，对我们理解植物细胞生物学至关重要。此外，了解细胞形状是如何被控制的可能允许操纵细胞形状，从而使细胞功能，在重要的作物植物农业效益。研究植物细胞形状控制的最佳模型系统之一是高等植物拟南芥（鼠耳衣）上的毛状体。皮层微管阵列在控制植物细胞扩增方向方面起着重要作用，是植物细胞形态的主要决定因素。然而，在细胞扩增方向的改变（如根毛或毛状分枝的形成）过程中，皮层mt的组织机制仍然是植物生物学中尚未解决的问题。我们正在使用遗传方法来识别参与特定的，局部细胞扩增事件的基因（最终是蛋白质）-毛状分支的起始。拟南芥毛状体是大的单细胞，由茎上的三到四个分枝组成。本文重点研究了新近发现的控制毛状体分支位置和长度的4个位点（不对称分支[ASB]位点）。最近的证据表明，MT细胞骨架在毛状体分支的形成中起重要作用，而肌动蛋白细胞骨架在毛状体扩张中起主导作用。提出的研究的直接目标是测试关于ASB突变体中肌动蛋白和MT细胞骨架组织的假设，并确定ASB基因（控制分支位置）与控制分支数量的基因之间的遗传关系。一旦基因克隆成功，细胞骨架研究以及基因分析将为ASBgene产物的功能解剖提供一个框架。完成所提出的研究目标将提供有关控制细胞扩增机制的关键信息。由于植物细胞共用细胞壁，因此在发育过程中不能像动物细胞那样长距离迁移，因此细胞扩增的方向是植物形态发生的主要决定因素。因此，植物控制局部细胞扩增的精确空间模式的机制是我们理解植物发育的核心

0091393Oppenheimer Plant cell shape plays a crucial role in plant cell function. Because of this relationship, understanding how plant cell shape is controlled is of fundamental importance to our understanding of plant cell biology. In addition, understanding how cell shape is controlled may allow the manipulation of cell shape, and hence cell function, in important crop plants for agricultural benefit. One of the best model systems for studying the control of plant cell shape is the trichome, or plant hair, on the higher plant Arabidopsis thaliana (mouse ear cress).It is well established that the cortical microtubule (MT) array plays a large role in controlling the direction of plant cell expansion which is the major determinant of plant cell shape. However, the mechanisms that organize the cortical MTs during a change in the direction of cell expansion (such as initiation of root hairs or trichome branches) remain an unresolved problem in plant biology. We are using a genetic approach to identify the genes (and ultimately the proteins) that participate in a specific, localized cell expansion event-the initiation of trichome branches. Arabidopsis trichomes are large, single cells consisting of three or four branches on a stalk. This proposal focuses on four newly discovered loci (the ASYMMETRIC BRANCH [ASB] loci) that control trichome branch position and length. Recent evidence suggests that the MT cytoskeleton plays an important role in trichome branch initiation, whereas the actin cytoskeleton plays a leading role in trichome expansion.The immediate goals of the proposed research are to test hypotheses concerning the organization of the actin and MT cytoskeletons in ASB mutants, and to determine the genetic relationship of the ASB genes (which control branch position) to the genes that control branch number. The cytoskeleton studies, along with the genetic analyses, will provide a framework for a functional dissection of the ASBgene products once the genes are cloned. Accomplishing the objectives of the proposed research will provide critical information about the mechanisms by which cell expansion is controlled. Because plant cells share cell walls and thus cannot migrate large distances during development like animal cells, the direction of cell expansion is a primary determinant of plant morphogenesis. Therefore, mechanisms by which plants control the precise spatial pattern of localized cell expansion is central to our understanding of plant development