The Role of Brassinosteroid Inactivation in Plant Development

类甾醇是参与调节植物发育以响应环境变化的生长促进激素。大多数油菜素类固醇的研究使用模式植物拟南芥集中在这些激素的生物合成或受体介导的信号通路。PI之前进行的研究主要集中在油菜素类固醇失活酶CYP 734 A1和CYP 72 C1上，并证明通过失活实现了调节这些激素水平的重要模式。遗传分析表明，这些酶共同作用，调节植物发育的许多方面。生物化学分析表明，这两种酶通过不同的机制使油菜素类固醇降解。在这个项目中，将采取生化方法来测试CYP 734 A1结合多种活性油菜素类固醇的假设，这样做与不同的亲和力。将使用类似的方法来检验CYP 72 C1通过与CYP 734 A1不同的生化机制灭活油菜素类固醇的假设。分子遗传学分析将被用来测试的假设，CYP 734 A1和CYP 72 C1有重叠，以及在植物发育中的独特作用。将使用类似的方法来检验CYP 734 A1和CYP 72 C1介导的油菜素类固醇失活途径与另一种油菜素类固醇失活酶UCG 73 C5相互作用的假设。这些研究将有助于揭示调节油菜素类固醇失活的机制，以及这一过程如何影响植物发育的许多方面。该项目的发现将影响多个研究领域，包括植物发育，油菜素类固醇和其他植物激素，酶功能和协同/冗余遗传相互作用的研究。这些研究将直接有助于博士的教育。学生，博士后，本科生和高中生。

Brassinosteroids are growth-promoting hormones involved in modulating plant development in response to changes in the environment. Most brassinosteroid investigations using the model plant Arabidopsis have concentrated on either the biosynthesis of these hormones or on the receptor-mediated signaling pathways. Previous research undertaken by the PI has focused on the brassinosteroid-inactivating enzymes, CYP734A1 and CYP72C1 and demonstrated that an important mode of regulating the level of these hormones is achieved through inactivation. Genetic analysis demonstrates that these enzymes act together to regulate many aspects of plant development. Biochemical analysis demonstrates that these two enzymes inactivate brassinosteroids, doing so via different mechanisms. In this project, a biochemical approach will be taken to test the hypothesis that CYP734A1 binds multiple active brassinosteroids, doing so with different affinities. Similar approaches will be used to test the hypothesis that CYP72C1 inactivates brassinosteroids via a different biochemical mechanism than CYP734A1. Molecular-genetic analysis will be used to test the hypothesis that CYP734A1 and CYP72C1 have overlapping as well unique roles in plant development. Similar approaches will be used to test the hypothesis that the CYP734A1- and CYP72C1-mediated brassinosteroid-inactivation pathway interacts with another brassinosteroid-inactivating enzyme, UCG73C5. These studies will help reveal the mechanisms regulating brassinosteroid inactivation and how this process affects many aspects of plant development. Findings from this project will impact multiple areas of research including studies of: plant development, brassinosteroids and other plant hormones, enzyme function, and synergistic/redundant genetic interactions. These studies will contribute directly to the education of a Ph.D. student, a postdoc, undergraduates and high school students.