Submitted to: Proceedings of the National Academy of Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2003
Publication Date: 9/5/2003
Citation: ACKHUNOV, E.D., AKHUNOV, A.R., LINKIEWICZ, A.M., DUBCOVSKY, J., HUMMEL, D., LAZO, G.R., CHAO, S., ANDERSON, O.D., DAVID, J., QI, L. SYNTENY PERTURBATIONS BETWEEN WHEAT HOMOEOLOGOUS CHROMOSOMES CAUSED BY LOCAL DUPLICATIONS AND DELETIONS CORRELATE WITH RECOMBINATION RATES. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES. 2003. 100:10836-10841. Interpretive Summary: Recent findings about the placement of genes expressed in wheat are providing an insight into the organization of the wheat genome. Genes in wheat were tentatively placed on genetic maps constructed from a complex series of screenings against mapping lines. The genes, represented by expressed sequence tags (ESTs), were used as DNA probes to survey the expressed portion of the wheat genome. Over 3,977 probes were analyzed, being placed into 159 different bin locations of the wheat genome map. Comparisons were made between all loci placed on the seven chromosomes of the A, B, and D genome groups of the hexaploid wheat. There were twice as many unique loci in the B genome than in the A and D genomes, as well as less frequent co-linear order of probes. Many insertions and deletions of loci were detected when comparisons were made between the chromosome groups, and pointed to higher recombination at the distal ends of the chromosomes. The organization of a framework wheat map will provide a resource for developing markers for breeding and set the stage for more detailed analysis of the wheat genome.
Technical Abstract: Loci detected by Southern blot hybridization of 3,977 expressed sequence tag unigenes were mapped into 159 chromosome bins delineated by breakpoints of a series of overlapping deletions. These data were used to assess synteny levels along homoeologous chromosomes of the wheat A, B, and D genomes, in relation to both bin position on the centromere-telomere axis and gradient of recombination rates along chromosome arms. There were twice as many unique loci in the B genome than in the A and D genomes, and synteny levels between the B genome chromosomes and the A and D genome homoeologues were lower than those between the A and D genome homoeologues. These differences among the wheat genomes were attributed to differences in the mating systems of wheat diploid ancestors. Synteny pertubations were characterized in 31 paralogous sets of loci with perturbed synteny. Both insertions and deletions of loci were detected and both preferentially occurred in high recombination regions of chromosomes.