A Genetic and Molecular Approach to Investigating the Relationship Between Root and Nodule Development in the Model Legume, Medicago Truncatula

[02:12 . 92]哈里斯这个项目的长期目标是了解固氮根瘤是如何在豆科植物的根部发育的。由于根瘤的形成是一个植物发育过程，是大多数豆科植物发育的正常组成部分，因此这个过程应该在正常根系发育的背景下进行研究。为什么只有豆科植物形成固氮根瘤菌？也许发育差异的根源在于它们与根瘤菌相互作用的能力。特别是，侧根被认为是固氮根瘤的潜在进化前体，基于它们的发育相似性。这个项目的直接目标是研究根系发育和结瘤之间的关系。本项目的具体目标是：1。确定根系发育基因在结瘤过程中的作用。这个问题将采用遗传和分子相结合的方法来解决。对根瘤和根系发育所需基因的突变体筛选将继续进行。同时，已知的根发育基因的表达将在正在发育的根瘤中进行检测。最后，在上述筛选中鉴定的lat1-1突变体的表型将被更详细地表征。2. 定位根瘤和根发育所需的基因LAT1，并鉴定跨越这一遗传区间的基因组BAC克隆。LAT1是目前发现的与侧根发育和根瘤形成有关的少数基因之一。因此，该基因为研究结瘤和根系发育的遗传程序之间的交集提供了一个工具。在本项目期间，将对LAT1基因进行精细定位，鉴定跨越该区间的基因组BAC克隆，为今后LAT1基因的克隆奠定基础。3. 用形态学和分子标记描述豆科植物侧根的发育特征：有什么独特的特征吗？为了解决这个问题，将产生分子标记，在很早的阶段标记侧根，并允许通过侧根发育观察被标记的细胞。通过这种方式，可以确定M. truncatula侧根发育的阶段，并可以作为一个框架来检查响应Specific Aim 1中鉴定的突变体的侧根发育。

0212992HarrisThe long-term goal of this project is to understand how nitrogen-fixing nodules develop on the roots of legumes. Since nodule formation is a plant developmental program, and is a normal part of the development of most legumes, this process should be studied within the context of normal root development. Why is it that only legumes form nitrogen-fixing nodules with rhizobia? Perhaps a difference in development lies at the root of their ability to interact with rhizobia. In particular, lateral roots have been proposed as a potential evolutionary precursor of nitrogen-fixing nodules, based on their developmental similarities. The immediate goal of this project is to examine the relationship between root development and nodulation. The specific aims of this project are:1. Determine the role of root development genes in the process of nodulation.This problem will be addressed using a combined genetic and molecular approach. The mutant screen for genes required both for nodule and root development will be continued. In parallel, the expression of known root development genes will be examined in the developing nodule. Finally, the phenotype of the lat1-1 mutant, identified in above screen, will be characterized in more detail. 2. Map LAT1, a gene required for both nodule and root development and identify genomic BAC clones that span this genetic interval.LAT1 is one of the few genes currently identified that links lateral root development and nodule formation. Thus this gene provides a tool to examine the intersection between the genetic programs for nodulation and root development. During the period of this project, the LAT1 gene will be finely mapped and genomic BAC clones spanning this interval identified, laying the groundwork for the future cloning of the LAT1 gene. 3. Characterize lateral root development in a legume using morphological and molecular markers: Are there any unique features? To address this question, molecular markers will be generated that label lateral roots at a very early stage and allow the observation of the marked cells through lateral root development. In this way, stages of lateral root development in M. truncatula will be identified, and can be used as a framework to examine lateral root development in mutants identified in response Specific Aim 1.