The Role of Brassinosteroid Inactivation in Plant Development

油菜素内酯是一种促进生长的激素，参与调节植物的发育以应对环境的变化。大多数使用模式植物拟南芥的油菜素内酯研究都集中在这些激素的生物合成或受体介导的信号通路上。PI先前的研究主要集中在油菜素类固醇失活酶CYP734A1和CYP72C1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，这些酶共同调控植物发育的许多方面。生化分析表明，这两种酶通过不同的机制使油菜素内酯失活。在本项目中，将采用生化方法来验证CYP734A1结合多种活性油菜素内酯的假设，并以不同的亲和力结合。将使用类似的方法来验证CYP72C1通过与CYP734A1不同的生化机制使油菜素内酯失活的假设。分子遗传学分析将用于验证CYP734A1和CYP72C1在植物发育中具有重叠和独特作用的假设。类似的方法将用于验证CYP734A1-和cyp72c1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UCG73C5相互作用的假设。这些研究将有助于揭示调控油菜素内酯失活的机制以及这一过程如何影响植物发育的许多方面。该项目的研究结果将影响多个领域的研究，包括：植物发育、油菜素内酯和其他植物激素、酶功能和协同/冗余遗传相互作用。这些研究将直接有助于博士生、博士后、本科生和高中生的教育。

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.