Molecular systematics of the temperate IR-lacking Clade of Papilionoid Legumes (Leguminosae) and the Evolution of Nod Factor Receptor Genes

豆科植物在农业和经济上的重要性仅次于牧草，有大量的种类作为园艺品种种植或作为粮食、饲料、纤维、燃料、油料、木材、药品和化学品的作物而收获。在“蝶形”亚科中，许多为食用和饲用而种植的常见驯化物种，包括紫花苜蓿、鹰嘴豆、扁豆、豌豆、三叶草、蚕豆，在技术上被称为缺乏反向重复分支或“IRLC”。IRLC约有50个属和4,350多种(占所有豆科植物的23%)，包含了绝大多数草本豆科植物，这些豆科植物在世界温带地区，特别是北美和欧亚大陆，地理上分布广泛，往往具有生态优势。这一组还包括一些用作遗传学和基因组学研究的模式植物系统的物种(紫花苜蓿、豌豆)和共生固氮(紫花苜蓿和三叶草)，以及几个大的属，作为适应辐射或多样化的例子。尽管在这个类群中有许多具有生物学意义、农业意义和生态重要性的物种，但对这个类群进行的广泛的系统研究相对较少，许多与其成员之间的分类学和进化关系有关的问题仍然没有解决。这个项目的主要目标是1)利用基于多个叶绿体和核基因序列的系统发育(或树)来澄清IRLC中的关系；2)在属的水平上构建一个反映其系统发育关系的最新分类；以及3)利用系统发育学来研究关于这一组的生物学、生态学和进化的有趣和潜在有用的问题，例如估计物种多样化的速度和模式，以及对于建立豆类和固氮根瘤细菌之间的共生关系所必需的基因的进化。这一项目的一个重要成果将是大大改善对这一组蝶形豆科植物的历史和生物多样性的了解，这类豆科植物几乎占该科所有物种的四分之一。此外，这些结果将促进更好地理解一些对整个家族有影响的基本生物学问题，例如豆类宿主特定识别固氮菌所需基因的保护和进化。该项目将促进美国和国际合作者之间的合作，而研究生和本科生将通过参与该项目的所有阶段，接受当代系统生物学以及DNA测序、系统发育重建和生物信息学的当前技术方面的培训。将通过在会议、出版物、向豆类信息网站(例如，Ildis、LIS)和公众可访问的数据库(Genbank、生命之树项目、TreeBASE)提交材料，向公众和科学界广泛传播成果，此外，还将创建一个专门的网站，作为关于这类豆科植物的生物多样性、系统发育和农业经济重要性信息的综合资源。

The legumes (plant family Leguminosae) are second only to the grasses in agricultural and economic importance, with a large number of species planted as horticultural varieties or harvested as crops for food, forage, fiber, fuel, oils, timber, medicines, and chemicals. Within the "papilionoid" subfamily many of the familiar domesticated species grown for food and forage, including Medicago (alfalfa), Cicer (chick pea), Lens (lentil), Pisum (pea), Trifolium (clover), Vicia (faba bean), are members of a group technically known as the inverted repeat lacking clade or "IRLC". The IRLC, with ca. 50 genera and more than 4,350 species (23% of all legumes), contains the vast majority of herbaceous legumes that are geographically widespread and often ecologically dominant in temperate regions of the world, especially North America and Eurasia. This group also contains a number of species used as model plant systems for the study of genetics and genomics (Medicago truncatula, Pisum sativum) and symbiotic nitrogen fixation (Medicago and Trifolium species), as well as several large genera that serve as examples of adaptive radiation or diversification. In spite of the number of biologically interesting, agriculturally, and ecologically important species in this group, relatively few broad-level systematic studies on this group have been undertaken and many issues related to the taxonomy and evolutionary relationships among its members remain unresolved. The primary goals of this project are 1) the clarification of relationships in the IRLC using phylogenies (or trees) based on sequences of multiple plastid and nuclear genes; 2) to construct an up-to-date classification of this group at the generic level that reflects their phylogenetic relationships; and 3) to use the phylogeny to study interesting and potentially useful questions about the biology, ecology, and evolution of this group, such as estimating rates and patterns of species diversification, and the evolution of genes essential to establishment of the symbiotic relationship between legumes and nitrogen-fixing rhizobial bacteria. An important outcome of this project will be a much-improved understanding of the history and biodiversity of this group of papilionoid legumes, which includes almost one quarter of all species in the family. Furthermore, these results will promote a greater understanding of a number of fundamental biological questions that have implications for the entire family, such as the conservation and evolution of genes required for the specific recognition of nitrogen-fixing bacteria by their legumes hosts. This project will foster collaborations among US and international collaborators, while graduate and undergraduate students will receive training in contemporary systematic biology as well as current techniques of DNA sequencing, phylogeny reconstruction, and bioinformatics through participation in all phases of the project. Results will be widely disseminated to both the general public and the scientific community through presentations at meetings, publications, contributions to legume information websites (e.g., ILDIS, LIS) and publicly accessible databases (Genbank, Tree of Life Project, TreeBASE), in addition to the creation of a dedicated website to serve as an comprehensive resource for information on the biodiversity, phylogeny, and agro-economic importance of this group of legumes.