Genetic map-physical map relationships for homoeologous group 5 in wheat established using microsatellites

摘要

Since deletion lines are an ideal material for physically allocating ESTs and genes to small chromosomal regions in bread wheat, we characterized a set of 84 deletion lines covering the 21 chromosomes of wheat using 682 microsatellites. We localized these microsatellite loci to 94 breakpoints in an homozygous state (88 of them being distal deletions, six remaining interstitial), and five in an heterozygous state representing 159 deletion bins. We identified 105 new commonly mapped loci between genetic and physical maps (52 and 53 for ITMI and CtCS maps, respectively). Only a few discrepancies concerning marker order were observed. Using 121 microsatellites from homoeologous group 5, respectively ten, twelve and nine junctions were described for chromosomes 5A, 5B and 5D resulting in 28 deletion bins (nine for 5A, eleven for 5B and eight for 5D). Differences were noticed concerning the relationships between genetic and physical distances. We observed small genetic distances over large physical regions around the centromeres and large genetic to physical map ratios close to the telomeres. Chromosomes from homoeologous group 2 and 5 were the best covered (122 and 121 microsatellites respectively) while the coverage for those from group 4 was scarcer(69 microsatellites). The mapped microsatellite loci will be useful for deletion stock verifications as well as allocating of associated QTLs to deletion bins where numerous ESTs that could be potential candidate genes are currently assigned.