NSF Award Abstract - #0321664

AWSFL008-DS3

Comparative Analysis of Legume Genome Evolution

Abstract

In the U.S., soybean (Glycine max) is second only to corn in total acres planted and is a primary source of proteins and oils for both animal and human consumption. A major feature of the soybean genome is a duplication event estimated to have occurred 9 million years ago. Similar polyploidization events are believed to have occurred multiple times in the evolutionary history of most, and perhaps all, flowering plants, and have lead to dramatic changes in genome structure. Major questions regarding the process of genome restructuring following polyploidization remain to be answered. Comparative genomic analyses will be used to identify patterns of gene rearrangement associated with both old (9 mya) and recent (<50 kya) polyploidy events in the Glycine genus. Specifically, an approximately 1 megabasepair interval from each of six legume taxa will be sequenced, as will the duplicated regions in the polyploid members (12 intervals in total). These taxa include two soybean cultivars, the closest true diploid relative of soybean Teramnus labialus and a recent polyploidy relative, Glycine tomentella G1188, that has twice as many chromosomes as soybean. The genomic interval to be sequenced contains several commercially important disease resistance (R) genes in soybean, and contains both rapidly rearranging and relatively stable chromosomal blocks. These analyses will address fundamental questions regarding genome evolution on both short (<100,000 years) and long (>50 million years) time scales, as well as questions regarding the evolution of R genes. This sequence collection will also facilitate identification of conserved promoter elements and non-coding RNAs, and well as commercially useful R genes. All sequence data, physical maps, and analyses will be made publicly available through a project web-site. This project will also generate new public software for phylogenetic analysis of genome rearrangements, and bacterial artificial chromosome (BAC) libraries of 5 legume species. The project will be linked to the educational and non-science community via direct collaborations with two hands-on science museums in Bloomington, Indiana and Blacksburg, Virginia, and by two high school outreach programs at the University of Minnesota and Cornell University. Hands-on activity kits will be developed that will be used for public events at museums, and more importantly in K-12 classrooms. Classroom use will be promoted through a series of teacher training workshops hosted at each museum. All kits will be specifically designed to address state academic standards in science and will teach principles in plant biology and evolution.