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

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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.