REU: Molecular Systematics of the Legume Tribe Phaseoleae and Allies

菜豆亚科是豆科植物中最大的分类支系。在部落的80多个属中，有许多常见的食用植物，包括菜豆、利马豆、大豆、风信子、木豆、豌豆、绿豆和菜豆。尽管该部落在经济上很重要，但在大多数情况下，该属之间的关系鲜为人知。康奈尔大学的杰弗里·道尔博士将在这个项目中提出三个层次的系统问题：1)属的自然分类是什么？2)属的自然类群之间是如何联系的？3)部落作为一个整体是一个自然的、单系的群体吗？第三个问题对豆科整个蝶形亚科的系统发育具有重要的意义，因为部落分类学主要是基于一些关键的形态特征，这些特征的有效性值得怀疑。因此，为了解决第三个问题，还将研究菜豆亚科以外的类群。研究中要分析的特征是分子性质的。初步工作表明，叶绿体DNA(CpDNA)的两个主要结构突变将有助于在菜豆亚族水平上划分属群，以及与木本植物相关的部落群的划分。储存蛋白基因中的插入序列描述了大豆及其近亲的特征。编码胞质葡糖磷酸异构酶的基因在豆科的许多成员中都是沉默的。因此，该项目的第一阶段将是使用这种罕见的突变来划分分类群组，至少为提出的问题提供部分答案。一旦定义了自然类群，就可以通过cpDNA图谱和特定基因的测序等技术来研究属之间的精确关系。

The Phaseoleae is the largest taxonomic tribe of the legume family. Among the more than 80 genera of the tribe are a number of familiar food plants including the garden bean, lima bean, soybean, hyacinth bean, pigeon pea, cowpea, mungbean, and jack bean. Despite the economic importance of the tribe, relationships among the genera are in most cases poorly known. Three levels of systematic questions will be addressed by Dr. Jeffrey Doyle of Cornell University in this project: 1) what are the natural grouping of genera? 2) how are natural groups of genera related to one another? and 3) is the tribe as a whole a natural, monophyletic group? This third question has important implications for the phylogeny of the entire papilionoid (bean) subfamily of the Leguminosae, because the tribal taxonomy is based largely on a few key morphological characters of dubious validity. Thus to address the third question, groups outside the Phaseoleae will also be studied. The characters to be analyzed in the research are molecular in nature. Preliminary work has shown that two major structural mutations of chloroplast DNA (cpDNA) will be useful for the circumscription of groups of genera at the levels of subtribe within the Phaseoleae and of groups of tribes related to the woody Millettieae. An insertion sequence in a storage protein gene characterizes the soybean and its close relatives. A duplication for the gene encoding cytosolic glucosephosphate isomerase has been silenced in various members of the Phaseoleae. The first stage of the project, therefore, will be to use such rare mutations to delimit groups of taxa, affording at least partial answers to the questions posed. Once natural groups are defined, precise relationships among genera can be studied by such techniques as cpDNA mapping and the sequencing of particular genes.