Medicago Truncatula as the Nodal Species for Comparative and Functional Legume Genomics

豆科植物是世界上最重要的植物类群之一，是人类饮食中蛋白质、动物饲料和饲料作物、油料作物以及生物圈中可用氮的重要来源。 此外，几种作物豆类是最具特征的植物遗传系统，具有许多经典的遗传标记，发达的DNA标记图谱和基因组分析的基本工具。 然而，尽管私人和公共资源投入了大量资源，但基因组庞大而复杂以及引入外源基因的困难等特征严重限制了作物豆类分子分析的步伐。 为了满足豆科植物对简单遗传系统的需求，研究人员选择了蒺藜苜蓿作为豆科生物学的模式物种。 与主要作物豆科植物不同，蒺藜苜蓿适合于有效的分子和遗传分析，并且非常适合于相关作物豆科物种重要的生物学问题的研究。 该项目将对蒺藜苜蓿的总DNA进行大规模分析，称为“基因组”。 特别是，基因组织图（比较基因组学）和它们在植物生物学中的功能图（功能基因组学）是该项目的重点。 该研究小组的最新结果首次证明了蒺藜苜蓿和豆科作物之间以及蒺藜苜蓿和特征良好的模式植物拟南芥之间的保守基因组结构。 在模式植物和相关作物物种之间保持基因组结构是非常重要的，因为它有望加快克隆和鉴定重要农艺学基因和性状的步伐。在该计划下开展的研究活动将包括以下方法：（1）比较基因组学，包括比较蒺藜苜蓿、豆科作物豌豆、苜蓿和大豆之间的基因组织，和充分表征的模式植物拟南芥;（2）功能基因组学，其将涉及构建和表征表达基因序列文库，并进行大规模基因表达分析以研究基因功能，以及（3）生物信息学，这将涉及开发一个数据库和数据库资源，用于分析和传播蒺藜苜蓿基因组信息。这项研究将整合豆类的遗传和功能信息，从而扩大对经济上重要的豆类物种进行基础和应用研究的机会。 这项研究将使科学家能够比较蒺藜苜蓿和相关作物豆类的农艺和科学兴趣的基因。 这些知识将使人们能够更有效地克隆和鉴定抗病性和作物产量等有价值的基因和性状，并最终促进改良作物品种的开发。 通过这项研究产生的表达基因数据库将能够详细分析特定基因在植物生长和发育中的作用。 在这项研究过程中发现的许多基因将成为作物改良策略和豆类生物学家继续科学研究的重点。 拟议的工作极大地受益于以前的NSF赞助的研究模式植物拟南芥。 同样，该项目的完成不仅有利于豆类研究，也有利于更广泛的科学界。

The legume family is one of the most important groups of plants worldwide, as an important source of protein in the human diet, of fodder and forage crops for animals, of oil crops, and for available nitrogen in the biosphere. Moreover, several crop legumes are among the best characterized plant genetic systems, with numerous classical genetic markers, well developed DNA marker maps, and basic tools for genome analysis. Nevertheless, despite the investment of considerable resources from private and public sources, features such as large and complex genomes, and difficulties with introduction of foreign genes have severely limited the pace of molecular analysis in crop legumes. In response to the need for a simple genetic system in legumes, investigators selected Medicago truncatula as a model species for legume biology. Unlike the major crop legumes, Medicago truncatula is amenable to efficient molecular and genetic analyses and it is well suited for study of biological issues important to the related crop legume species. This project will undertake the large scale analysis of Medicago truncatula's total DNA, called its "genome". In particular, a map of the organization of genes (comparative genomics), and of their functions in plant biology (functional genomics), are the emphases of this project. Recent results from this research team document the first indications of conserved genome structure between Medicago truncatula and crop legumes and between Medicago truncatula and the well-characterized model plant Arabidopsis thaliana. Conserved genome structure between model plants and related crop species is significant because it is expected to accelerate the pace of cloning and characterization of agronomically important genes and traits.Research activities conducted under this program will encompass the following approaches: (1) comparative genomics, which will involve comparing the organization of genes between Medicago truncatula the crop legumes pea, alfalfa, and soybean, and the well-characterized model plant Arabidopsis thaliana; (2) functional genomics, which will involve constructing and characterizing a library of expressed gene sequences, and conducting large scale gene expression analysis to study gene function, and (3) bioinformatics, which will involve developing a database and database resources for analysis and dissemination of Medicago truncatula genome information.The long term impact of this research will be to integrate genetic and functional information across legumes, and thereby expand opportunities for basic and applied research in economically important legume species. This research will allow scientists to compare genes of agronomic and scientific interest in Medicago truncatula and the related crop legumes. This knowledge will enable more efficient cloning and characterization of valuable genes and traits, such as disease resistance and crop productivity, and it will ultimately facilitate the development of improved crop varieties. The database of expressed genes generated by this research will enable the detailed analysis of the role of specific genes in plant growth and development. Many of the genes identified in the course of this research will become the focus of crop improvement strategies and of continued scientific investigation by legume biologists. The proposed work benefits enormously from previous NSF-sponsored research on the model plant Arabidopsis thaliana. Likewise, completion of the project will benefit not only research on legumes, but the broader scientific community as well.