Early Career Speaker: Evolution of Genome Structure in Polyploid Wheat Revealed by Comparison of Wheat and Aegilops tauschii Whole-Genome BioNano Maps

It has been suggested that changes in genome structure and expression played an important role in the evolution of hexaploid wheat (genomes AABBDD). Hexaploid wheat originated about 8,000 years ago via hybridization of tetraploid wheat (genomes AABB) with diploid Aegilops tauschii (genomes DD). Because of this recent origin, it may be possible to detect and analyze in detail structural changes that have taken place in the wheat D genome. Genome-wide BioNano genome (BNG) maps are an exceptionally powerful tool for genome comparisons. We discuss the construction of BNG maps for Ae. tauschii and wheat and their subsequent comparison for the detection of structural differences between the D genome of wheat and that of Ae. tauschii. These comparisons revealed that a vast majority of these changes are indels. The BNG map comparisons can identify those that have taken place during wheat evolution, precisely locate them, and assess the role of recombination and location on the centromere-telomere axis in their origin. This work is a part of the NSF-funded Project IOS-1238231 to generate a reference sequence for the genome of Ae. tauschii (http://aegilops.wheat.ucdavis.edu/ATGSP/).