Phylogenetic Analysis of Eurasion Allotetraploid Species of Elymus (Gramineae) Based on Four Molecular Data Sets.

0426194Mason-Gamer 伊利诺伊大学芝加哥分校的 Roberta Mason-Gamer 博士进行的研究旨在阐明披碱草属草属中几个欧洲和亚洲物种的进化历史。 披碱草与小麦、大麦和黑麦一起属于小麦族、小麦科。 从进化的角度来看，披碱草因其复杂的遗传历史而很有趣。 虽然遗传上最简单的二倍体小麦科成员有两套完整的染色体（每个亲本各一套，就像人类一样），但披碱草个体有四套、六套甚至八套完整的染色体，代表来自两个或多个遗传和进化上不同的祖先的组合基因组。 这项研究重点关注原产于欧洲和亚洲的披碱草的四基因组（四倍体）成员，并直接建立在对北美四倍体披碱草物种的早期研究基础上。 该研究的目的是利用四种不同分子标记的 DNA 序列数据来阐明 18 种复杂的欧亚物种的进化历史。 更具体地说，目标是：（1）鉴定每个物种的二倍体母本和父本祖先，以及（2）评估披碱草内的遗传多样性模式是否与广泛的地理模式相对应，或者与先前观察到的外部可见形态变异的模式相对应。 当这些物种的数据与北美四倍体的现有数据相结合时，这项研究将涵盖迄今为止使用详细的分子系统发育方法检查的最大的多倍体群体。多倍体研究有助于了解地球上开花植物的非凡多样性，因为所有开花植物物种中多达一半是多倍体起源的。 多倍体不仅代表植物物种形成的主要机制，而且一些最重要的农作物也是多倍体，包括苜蓿、油菜、棉花、咖啡、十字花科蔬菜、马铃薯、大豆、烟草、小麦等。 因此，多倍体形成的机制和伴随多倍体的遗传变化引起了许多研究领域的植物科学家的广泛兴趣。 诸如此处描述的进化研究为详细探索多倍体的许多其他方面奠定了必要的基础。 除了深入了解 Elymus 的复杂历史外，该项目还将通过两种方式支持伊利诺伊大学芝加哥分校的学生教育。 首先，两名研究生将获得补助金的支持。 他们将深入参与遗传数据的收集、分析和解释。 他们从这次经历中获得的方法和思路将直接丰富自己的论文研究。 其次，本科生的参与将是完成该项目的重要组成部分。 该补助金提供勤工俭学的工资，还为希望获得完成研究项目的课程学分的学生提供用品费用支持。 本科生将学习许多广泛适用的实验室技术，包括 DNA 分离、基因扩增和 DNA 测序。

0426194Mason-Gamer Research by Dr. Roberta Mason-Gamer of the University of Illinois-Chicago is designed to clarify the evolutionary history of several European and Asian species in the grass genus Elymus. Elymus is classified within the wheat tribe, Triticeae, along with wheat, barley, and rye. From an evolutionary standpoint, Elymus is interesting because of its complex genetic history. While the genetically simplest, or diploid, members of the Triticeae have two complete sets of chromosomes (one set from each parent, just as in humans), Elymus individuals have four, six, or even eight complete sets, representing the combined genomes from two or more genetically and evolutionarily distinct ancestors. This research focuses on the four-genome (tetraploid) members of Elymus that are native to Europe and Asia, and builds directly upon earlier research on the tetraploid Elymus species of North America. The objective of the research is to clarify the evolutionary history of 18 of these complex Eurasian species using DNA sequence data from four different molecular markers. More specifically, the goals are to: (1) identify the diploid maternal and paternal progenitors of each species, and (2) assess whether patterns of genetic diversity within Elymus correspond either to broad geographic patterns, or to previously observed patterns of outwardly visible morphological variation. When data from these species are combined with existing data from the North American tetraploids, this research will encompass the largest group of polyploids examined to date using detailed molecular phylogenetic methods. Studies of polyploids are relevant to understanding the extraordinary diversity of flowering plants on earth, since as many as half of all flowering plant species are of polyploid origin. Not only does polyploidy represent a major mechanism of plant speciation, but some of our most important crop plants are polyploid, including alfalfa, canola, cotton, coffee, cruciferous vegetables, potatoes, soybeans, tobacco, wheat, and many others. Thus, mechanisms of polyploid formation and the genetic changes that accompany polyploidy are of broad interest to plant scientists in many fields of research. Evolutionary studies such as the one described here lay the necessary groundwork for detailed explorations of many other facets of polyploidy. In addition to providing insights into the complicated history of Elymus, the project will support student education at the University of Illinois at Chicago in two ways. First, two graduate students will be supported by the grant. They will be deeply involved with the collection, analysis, and interpretation of genetic data. Whatever they gain from this experience in terms of methods and ideas will directly enrich their own thesis research. Second, undergraduate student participation will be an important part of completing the project. The grant provides work-study wages, and also supports the cost of supplies for students who wish to receive course credit for completing research projects. Undergraduates will learn many broadly applicable laboratory techniques, including DNA isolation, gene amplification, and DNA sequencing.