Physical mapping of the short arm of chromosome 3 in aegilops tauschii and barley

Abstract

A research program has been established to generate fine physical and genetic maps of wheat and barley chromosomes 3 and 7. In association with the International Wheat and Barley Genome Sequencing Consortia, the ultimate goal is to use these maps to produce a full genome sequence, target specific genes for isolation and analysis and investigate the recombinational behavior of the complex Triticeae chromosomes. We made a first physical map of chromosome 3S using the BAC library of Aegilops tauschii, the ancestor of D genome. The target region was the telomeric 20 cM of the short arm of Group 3 chromosomes, delineated by an X-ray induced deletion mutation called ph2a and estimated to be around 80 Mb in size. About 100 EST were anchored on the contigs by using information from previous studies of the deletion mutant, the physical map of 3BS, the wheat deletion bin map and the barley genetic map. The physical map on Ae tauschii and barley genetic maps were linked and used to calculate the recombination rate across the region. The maps allowed us to compare the organization of the genes along the chromosome 3S in the H, B and D-ancestor genomes. The physical contigs will provide the base for further sequencing of chromosome 3S.