Analyses of Cell-Cell Interactions Required for Floral Development

9630716爱尔兰双子叶植物的花通常由四个轮生的花器官组成，这些花器官通过花分生组织的三个细胞层中的每一个细胞的协调增殖而产生。细胞间的相互作用对这种花型的发展很重要。这些细胞间信号事件可能包括轮间、器官间和层间相互作用。这个项目将调查这些可能的信号机制中的每一个在多大程度上参与建立花型。以前的工作表明，DTA基因在花瓣和雄蕊器官原基中的表达导致花瓣和雄蕊的消融。在嫁接实验中，将含有DTA基因构建的烟草植株与野生型植物嫁接，将被用来检验只消融部分花器官原基的效果。由此产生的嵌合植物可以用来评估剩余组织能在多大程度上再生部分或全部缺失的模式元件。这些实验的结果将有助于确定不同的信号过程在不同的花型规范中所起的作用程度。此外，还将确定花同源异型APETALA3(AP3)基因在拟南芥花发育过程中细胞-细胞相互作用中的作用。利用异源Ac/DS转座元件系统，将有可能产生野生型AP3和突变型AP3组织的嵌合体拟南芥植株。这些植物将被用来评估AP3基因产物在细胞间通讯中的作用。确定细胞间信号作用的参数，结合对单个基因产物在这些信号过程中的作用的分析，将导致对分生组织细胞如何协调它们的发育以形成分化的花的更全面的理解。

9630716 Irish The dicot flower generally consists of four whorls of floral organs, which arise through the coordinated proliferation of cells in each of the three cell layers of the floral meristem. Cell-cell interactions are important for the development of this floral pattern. These intercellular signaling events potentially include interwhorl, interorgan, and interlayer interactions. This project will investigate the extent to which each of these possible signaling mechanisms participates in establishing the floral pattern. Previous work has shown that expression of the DTA gene in the petal and stamen organ primordia results in ablation of petals and stamens. Grafing experiments, in which Nicotiana plants containing the DTA gene construct are grafted with wild type plants, will be used to examine the effects of ablating only part of the floral organ primordia. The resulting chimeric plants can be used to assess the degree to which remaining tissues can regenerate part or all of the missing patern elements. The results of these experiments will help to define the extent to which different signaling processes play in the specification of the differentiated floral pattern. In addition, the role of the floral homeotic APETALA3 (AP3) gene in cell-cell interactions in the development of the Arabidopsis flower will be defined. Using the heterologous Ac/Ds transposable element system, it will be possible to generate Arabidopsis plants that are mosaics of wild type AP3 and mutant ap3 tissues. These plants will be used to assess the role of the AP3 gene product in intercellular communication. Defining the parameters of where intercellular signals act, in combination with the analyses of the roles of individual gene products in these signaling processes, will lead to a more complete understanding of how meristematic cells coordinate their development to form the differentiated flower.