CAREER: Analysis of Signalling in Arabidopsis Carpel Patterning

本研究的目的是了解调节拟南芥果实模式的信号网络。经典实验表明，在植物果实发育过程中，细胞间信号传导事件起着关键作用，但迄今为止，所涉及的信号和受体尚未被确定。本研究旨在了解拟南芥果实大小和形态是如何调控的。通过对拟南芥的插入突变体进行筛选，发现了四个受体激酶基因的突变体，这些突变体在果实的额外器官中具有共同的表型。这些基因的零等位基因的表型分析表明，这些受体激酶对果实发育轴的建立至关重要。由于观察到的受体突变体之间的共同表型，研究人员开始寻找潜在配体的可用突变，发现油菜素内酯可能在水果原基的细胞信号传导中起作用。初步数据表明，在产生果实的花分生组织中存在细胞信号传导的横向抑制模型。这项建议的具体目标是：(1)通过基因筛选确定该信号网络的更多组成部分，(2)通过分析受体激酶的表达模式和细胞水平上突变表型的表征来确定受体激酶是否参与侧向信号传导，(3)通过使用生化中间体、在单个步骤被阻断的突变体和油菜素内酯生物合成抑制剂来测试油菜素内酯在果实图案化中的作用。在本计画的教学部分，将会发展数个分子生物学电脑实验单元。这些课程是为分子生物学本科生的讲座课程设计的，其中一个模块后来将被修改，用于公立学校的推广。这些模块的目标是教授分子生物学的基本概念，并提高人们对生物技术如何影响我们日常生活的认识。一个模块将比较传统的植物育种方法和转基因方法，包括实验方法和发展作物的经济和生物学意义的分析。本模块将教授学生食物背后的生物学原理，并为他们未来的个人和政治决策做好准备。智力优势：拟南芥果实的大小和模式是如何调控的，这些实验的结果将告诉我们如何调控拟南芥果实的大小，并可应用于理解其他植物果实大小的调控。在驯化作物中，其中一些基因的同系物的变化可能是果实大小和形态多样性的原因。经典植物育种、分子遗传学和转基因植物发展之间相互作用的概念构成了提案教育部分的基础。这项工作的广泛影响：拟议的研究，测试调节拟南芥果实模式的信号事件模型，是跨学科的，结合了基因组学，遗传学，分子生物学和发育。这些实验将为本科生、研究生和博士后提供培训机会。这些实验也构成了为分子生物学课程开发计算机模块的基础。其中一个模块将在教师的投入下重新设计，并纳入一个正在进行的推广计划，向高中生传授植物育种策略和转基因生物。所有为课程开发的模块都将在互联网上提供给学生和教师。图森公立学校和亚利桑那大学的学生群体都提供了接触弱势群体学生的机会。

The goal of this research is to understand the signaling networks that regulate pattern in the Arabidopsis fruit. Classical experiments indicated a key role for intercellular signaling events during the development of the fruit in plants, but the signals and receptors involved have thus far not been identified. The aims of this proposal are to understand how fruit size and pattern are regulated in Arabidopsis. Using a screen of insertion mutants in Arabidopsis, mutants have been identified in four receptor kinase genes that share a common phenotype of extra organs in the fruit. The analysis of the phenotypes of the null alleles of these genes suggests these receptor kinases are critically important for establishing the developmental axes of the fruit. Because of the observed, shared phenotypes among the receptor mutants, a search was initiated for available mutations in potential ligands which revealed that brassinosteroids may play a role in cell signaling in the fruit primordia. The preliminary data suggests a lateral inhibition model of cell signaling in the floral meristem that produces the fruit. The specific aims of this proposal are: (1) to identify more components of this signaling network using genetic screens, (2) to determine if the receptor kinases are involved in lateral signaling through analysis of their expression patterns and characterization of the mutant phenotypes at the cellular level, and (3) to test the role of brassinosteroids in fruit patterning by using biochemical intermediates, mutants that are blocked at individual steps and an inhibitor of brassinosteroid biosynthesis.In the instructional portion of this project, several molecular-biology computer-lab modules will be developed. These are designed to accompany a lecture course for undergraduates in molecular biology, and one module will later be modified for public school outreach. The goals of these modules will be to teach basic concepts in molecular biology and to increase awareness of how biological technology affects our daily lives. One module will compare the traditional plant breeding approach with transgenic approaches, including both experimental methods and analysis of the economic and biological implications of developing crops. This module will teach students about the biology underlying the food they consume and prepare them for their future in both personal and political decision-making.Intellectual merit: The results of the proposed experiments will tell us how fruit size and pattern are regulated in Arabidopsis, and can be applied to understanding the regulation of fruit size in other plants. In domesticated crop plants, changes in the homologs of some of these genes may be responsible for the diversity in fruit size and morphology. This concept of the interplay between classical plant breeding, molecular genetics and the development of transgenic plants forms the basis of the educational part of the proposal.Broader impacts of this work: The proposed research, testing a model for signaling events that regulate patterning in Arabidopsis fruit, is interdisciplinary, combining genomics, genetics, molecular biology, and development. The experiments will provide training opportunities for undergraduates, graduate students and postdoctorals. The experiments also form the basis of some of the ideas for developing computer modules to accompany a molecular-biology lecture class. One of these modules will be redesigned with the input of teachers to be included in an ongoing outreach program to teach high-school students about plant-breeding strategies and genetically modified organisms. All modules developed for courses will be made available on the Internet for students and teachers. Both the Tucson public school and University of Arizona student populations provide opportunities to reach students from underrepresented groups.