Chromosomal genomics - genome scale dissection of gene order in wheat chromosomes. Exploring the Wheat Genome

We used a novel approach that incorporated chromosome sorting, second generation sequencing, array hybridization and systematic exploitation of conserved synteny with model grasses, to assign approximately 860f the estimated ~32,000 barley genes to individual chromosome arms. Using a series of bioinformatically constructed 'genome zippers' that integrate gene indices of rice, sorghum and Brachypodium in a conserved synteny model, we were able to assemble 21,766 barley genes in a putative linear order. We show that the barley (H) genome displays a mosaic of structural similarity to hexaploid bread wheat A, B and D subgenomes and that orthologous genes in different grasses exhibit signatures of positive selection in different lineages. We present an ordered, information-rich scaffold of the barley genome that provides a valuable surrogate for a whole genome sequence and a robust framework for the development of novel strategies in cereal breeding.