CAREER: Analysis of Signalling in Arabidopsis Carpel Patterning

本研究的目的是了解在拟南芥果实中调控模式的信号网络。经典实验表明，细胞间信号事件在植物果实发育过程中起着关键作用，但涉及的信号和受体到目前为止还没有确定。这项建议的目的是了解拟南芥果实的大小和模式是如何调控的。利用拟南芥中插入突变体的筛选，已经在四个受体激酶基因中鉴定出突变体，这些基因具有果实中额外器官的共同表型。对这些基因零等位基因的表型分析表明，这些受体激酶对于建立果实的发育轴是至关重要的。由于在受体突变体中观察到的共同表型，我们开始了对潜在配体的可用突变的搜索，这表明油菜素类固醇可能在果实原基的细胞信号中发挥作用。初步数据表明，在产生果实的花分生组织中，细胞信号的侧向抑制模型。这项建议的具体目标是：(1)利用遗传筛选来确定这个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特征来确定受体激酶是否参与侧向信号传递，以及(3)通过使用生化中间体、在各个步骤被阻止的突变体和油菜素类固醇生物合成的抑制剂来测试油菜素类固醇在果实模式中的作用。在这个项目的教学部分，将开发几个分子生物学计算机实验室模块。这些课程是为本科生开设的分子生物学课程而设计的，其中一个模块稍后将进行修改，以供公立学校推广使用。这些单元的目标将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。其中一个模块将比较传统的植物育种方法和转基因方法，包括实验方法和对发展作物的经济和生物学影响的分析。本模块将向学生传授他们所消费的食物背后的生物学知识，并为他们在个人和政治决策中的未来做好准备。智力优势：拟议的实验结果将告诉我们拟南芥中果实大小和模式是如何调节的，并可用于理解其他植物果实大小的调节。在驯化的农作物中，这些基因中的一些同源基因的变化可能是导致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的相互作用的概念构成了该提议的教育部分的基础。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的模型，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。这些实验也构成了开发计算机模块以配合分子生物学讲课的一些想法的基础。其中一个模块将在教师的参与下重新设计，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。为课程开发的所有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来自代表性不足群体的学生的机会。

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.