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

0212992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生长的。 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部分，因此应在正常根系发育的背景下研究这一过程。 为什么只有豆科植物能与根瘤菌形成固氮根瘤？ 也许发育上的差异是它们与根瘤菌相互作用能力的根源。 特别是，侧根已被提出作为一个潜在的进化前体的固氮结节，基于其发展的相似性。本项目的近期目标是研究根系发育和根系生长之间的关系。 该项目的具体目标是：1。确定根发育基因在根形成过程中的作用。这个问题将用遗传学和分子生物学相结合的方法来解决。 将继续进行根瘤和根发育所需基因的突变体筛选。 与此同时，将在发育中的根瘤中检查已知的根发育基因的表达。 最后，将更详细地表征在上述筛选中鉴定的lat 1 -1突变体的表型。 2.定位根瘤和根发育所需的基因LAT 1，并鉴定跨越此遗传区间的基因组BAC克隆。LAT 1是目前发现的少数几个连接侧根发育和根瘤形成的基因之一。 因此，该基因提供了一个工具，以检查之间的交叉遗传程序的生根和根的发展。在本项目期间，将对LAT 1基因进行精细定位，并鉴定跨越这一区间的基因组BAC克隆，为将来克隆LAT 1基因奠定基础。 3.用形态学和分子标记描述豆科植物侧根发育的特征：是否有任何独特的特征？为了解决这个问题，将产生分子标记，在非常早期的阶段标记侧根，并允许通过侧根发育观察标记的细胞。 因此，可以将M. truncatula将被鉴定，并且可以用作框架来检查在响应特异性目标1中鉴定的突变体中的侧根发育。

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.