Differential Expression of the Diverse Plant Actins

描述（申请人提供）：植物具有古老的生殖和营养肌动蛋白基因类，具有不同的表达模式。在上一个资助期间，我们检验了这些古老的肌动蛋白基因在维管植物进化过程中被保存下来的假设，因为它们具有不同的调节模式和/或因为它们表达功能上不同的肌动蛋白同变异体。我们将研究扩展到分析和肌动蛋白相关蛋白（ARP）家族，并鉴定了200多个由拟南芥基因组编码的肌动蛋白结合蛋白（ABP）。肌动蛋白、剖面和ARP基因的突变导致了多种信息表型，从影响细胞、器官和植物大小的表型到极端的形态差异，包括细胞极性、不育性和胚胎致死率的改变。我们通过制作许多亚类和等变异体特异性单克隆抗体来研究其不同的表达模式，探讨了肌动蛋白同变异体的重要性。我们已经证明，肌动蛋白异位表达，而不是过表达，会极大地破坏大多数器官和组织的发育。在下一个资助期，我们将应用各种细胞生物学、分子和遗传学方法来研究肌动蛋白、ARPs和ABPs的不同异位变体的作用。我们的新具体目标是：1)表征拟南芥肌动蛋白，ARP的表型，并分析突变体和突变体组合，重点关注这些基因最独特的功能；2)研究各种肌动蛋白同型异构体对器官、组织和细胞发育的功能意义；3)确定肌动蛋白结合蛋白（actin-binding protein isovariant, ABPs）器官和组织特异性表达（例如，profiling， ADF）的重要性；4)构建具有最小数量生殖和营养同变异体的植物，以进一步表征肌动蛋白和ABP同变异体之间的差异。

DESCRIPTION (provided by applicant): Plants have ancient classes of reproductive and vegetative actin genes with distinct expression patterns. During the last grant period we have examined the hypothesis that these ancient actin genes were preserved throughout vascular plant evolution because they have distinct patterns of regulation and/or because they express functionally distinct actin protein isovariants. We have extended our research to include the profiling and actin-related protein (ARP) families, and have identified more than 200 actin binding proteins (ABP) encoded by the Arabidopsis genome. Mutations in actin, profiling, and ARP genes have resulted in a variety of informative phenotypes ranging from those affecting cell, organ, and plant size to extreme morphological differences including alterations in cell polarity, sterility, and embryo lethality. We have explored the importance of actin protein isovariants by making numerous subclass- and isovariant-specific monoclonal antibodies to examine their distinct expression patterns. We have demonstrated that ectopic expression, but not overexpression, of actin isovariants dramatically disrupts the development of most organs and tissues During the next grant period we will apply a wide variety of cell biological, molecular, and genetic approaches to our research dissecting the roles of different isovariants of the actins, ARPs, and ABPs. Our new Specific Aims are: 1) to characterize the phenotypes of Arabidopsis actin, ARP, and profiling mutants and combinations of mutants focusing on the most distinct functions of these genes; 2) to investigate the functional significance of various actin isovariants to organ, tissue, and cell development; 3) to identify the significance of organ and tissue specific expression of actin-binding protein isovariants (ABPs) (e.g., profiling, ADF), and 4) to construct plants with a minimal complement of reproductive and vegetative isovariants to further characterize differences among actin and ABP isovariants.