Control of Plant Cell Shape by the ASB Loci in Arabidopsis

奥本海默植物细胞形态对植物细胞功能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控制的，对于我们理解植物细胞生物学是至关重要的。此外，了解细胞形状是如何控制的，可能会允许在重要的农作物中操纵细胞形状，从而控制细胞功能，从而使农业受益。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的毛状体或植物毛发。众所周知，皮质微管阵列在控制植物细胞扩张方向方面发挥着重要作用，而植物细胞扩张方向是植物细胞形状的主要决定因素。然而，在细胞扩展方向的改变(如根毛或毛状体分支的启动)期间组织皮质MT的机制在植物生物学中仍然是一个尚未解决的问题。我们正在使用遗传方法来识别参与特定的、局部的细胞扩张事件的基因(最终是蛋白质)--毛状体分支的启动。拟南芥毛状体是一个茎上由三到四个枝条组成的大的单细胞。这一建议集中在四个新发现的控制毛状体分支位置和长度的基因座(不对称分支[ASB]基因座)上。最近的证据表明，MT细胞骨架在毛状体分枝起始中起重要作用，而肌动蛋白细胞骨架在毛状体的扩展中起主导作用。本研究的近期目标是检验ASB突变体中有关肌动蛋白和MT细胞骨架组织的假说，并确定控制分支位置的ASB基因与控制分支数量的基因之间的遗传关系。细胞骨架研究，以及遗传分析，将为克隆基因后对ASB基因产物的功能剖析提供一个框架。完成拟议研究的目标将提供关于控制细胞扩张的机制的关键信息。由于植物细胞共享细胞壁，因此在发育过程中不能像动物细胞那样长距离迁移，因此细胞扩张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张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