Submitted to: Genome Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2003
Publication Date: 5/1/2003
Citation: AKHUNOV, E.D., LAZO, G.R., CHAO, S., ANDERSON, O.D., GUSTAFSON, J.P., WALKER-SIMMONS, M.K., STEBER, C.M. THE ORGANIZATION AND RATE OF EVOLUTION OF THE WHEAT TRANSCRIPTOME ARE CORRELATED WITH RECOMBINATION RATES ALONG CHROMOSOME ARMS. GENOME RESEARCH. 2003. V. 13(5). P. 753-763. Interpretive Summary: Wheat is one of the most important crops both within the U.S. and worldwide. Development of new and improved varieties into the future will depend on the basic knowledge of the organization and function of the genes found on the wheat chromosomes. This paper describes relationships between wheat chromosome structure and the exchange of genetic information through recombining gene and chromosome segments and the distribution and fate of duplicated genes. It was found the the fastest changing portions of the wheat chromosomes are the distal ends of the chromosomes - regions where gene duplication and DNA exchange between chromosomes is occurring the most rapidly. The paper also discusses the evolutionary significance of the findings and how it relates to the production of improved wheat varieties.
Technical Abstract: Genes detected by 3977 wheat expressed sequence tags were mapped into chromosome bins delineated by breakpoints of 159 overlapping deletions. These data were used to assess the organizational and evolutionary aspects of the wheat transcriptome (the sum of all genes and genelike nucleotide sequences present in the genome). Gene density and recombination rate increased with the relative distance of a bin from the centromere. Single-gene loci present once in the wheat genomes were found predominantly in the proximal, low-recombination regions, while multi-gene loci tended to be more frequent in distal, high-recombination regions. One-quarter of all gene motifs within wheat genomes were represented by two or more duplicated loci (paralogous sets). For 40 such sets, ancestral loci and loci derived from them by duplication were identified. Loci derived by duplication were most frequently located in distal, high-recombination chromosome regions whereas ancestral loci were most frequently located proximal to them. It is suggested that recombination has played a central role in the evolution of wheat transcriptome structure and that gradients of recombination rates along chromosome arms promote more rapid rates of transcriptome evolution in distal, high-recombination regions than in proximal, low-recombination regions.