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

伊利诺伊大学芝加哥分校的Roberta Mason-Gamer博士的Mason-Gamer研究旨在阐明披碱草属几个欧洲和亚洲物种的进化史。披碱草属与小麦、大麦和黑麦一起被归入小麦部落、小麦族和黑麦族。从进化的角度来看，披碱草之所以有趣，是因为它复杂的遗传史。虽然遗传上最简单的或二倍体的小麦科成员有两套完整的染色体(来自父母双方的一套，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，代表来自两个或更多在遗传和进化上截然不同的祖先的组合基因组。这项研究集中在原产于欧洲和亚洲的披碱草属四个基因组(四倍体)成员，并直接建立在早期对北美四倍体披碱草物种的研究基础上。这项研究的目的是利用来自四个不同分子标记的DNA序列数据来阐明这些复杂的欧亚物种中的18个物种的进化历史。更具体地说，目标是：(1)确定每个物种的二倍体母本和父本祖先；(2)评估披碱草属内的遗传多样性模式是否与广泛的地理模式相对应，或与先前观察到的外观可见的形态变异模式相对应。当来自这些物种的数据与来自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多倍体群体。对多倍体的研究与了解地球上开花植物的非凡多样性有关，因为多达一半的开花植物物种是多倍体起源的。多倍体不仅是植物物种形成的主要机制，而且我们最重要的一些农作物也是多倍体的，包括紫花苜蓿、油菜籽、棉花、咖啡、十字花科蔬菜、土豆、大豆、烟草、小麦等。因此，多倍体形成的机制和伴随多倍体产生的遗传变化引起了植物科学家在许多研究领域的广泛兴趣。这里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。除了提供对伊利莫斯复杂历史的洞察，该项目还将以两种方式支持伊利诺伊大学芝加哥分校的学生教育。首先，两名研究生将得到助学金的支持。他们将深入参与基因数据的收集、分析和解释。无论他们在方法和思路上获得了什么，都将直接丰富他们自己的论文研究。其次，本科生的参与将是完成该项目的重要组成部分。这笔助学金提供勤工俭学的工资，还支持那些希望通过完成研究项目获得课程学分的学生的用品费用。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.