Analyses of Cell-Cell Interactions Required for Floral Development

9630716 Irish双子叶植物的花通常由四轮花器官组成，它们是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的。 细胞间的相互作用对这种花型的形成很重要。 这些细胞间信号传导事件可能包括轮间、器官间和层间相互作用。 本项目将调查这些可能的信号机制中的每一种参与建立花型的程度。 先前的工作表明，在花瓣和雄蕊器官原基中的DTA基因的表达导致花瓣和雄蕊的消融。 嫁接实验，其中含有DTA基因构建体的烟草植物与野生型植物嫁接，将用于检查仅切除部分花器官原基的效果。 所得到的嵌合体植物可用于评估剩余组织可再生部分或全部缺失的模式元件的程度。 这些实验的结果将有助于确定在何种程度上不同的信号处理发挥的规格分化的花型。 此外，花同源异型APETALA 3（AP 3）基因在细胞间相互作用的拟南芥花的发展中的作用将被定义。 使用异源Ac/Ds转座因子系统，将有可能产生野生型AP 3和突变型AP 3组织嵌合体的拟南芥植物。 这些植物将用于评估AP 3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传导过程中的作用的分析，将导致对分生组织细胞如何协调其发育以形成分化的花的更完整的理解。

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.