Submitted to: Genome Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/18/2003
Publication Date: 5/1/2003
Citation: Akhunov, E.D., Goodyear, A.J., Geng, S., Qi, L., Echalier, B., Gill, B.S., Miftahudin, Gustafson, J.P., Lazo, G.R., Chao, W.S. 2003. The organization and rate of evolution of the wheat transcriptome are correlated with recombination rates along wheat chromosome arms. Genome Research. 13(5):753-763. Interpretive Summary: A comparison of the evolutionary changes that have taken place between chromosome regions of wheat was attempted. The present study was designed to attempt to compare the gene differences between various chromosomal regions of wheat. An understanding of differences in gene density along chromosome arms has evolved and changed over time and will be of considerable value in research and breeding programs designed to improve our understanding of the biology of wheat. We analyzed the wheat genomes based on gene order and gene recombination rates. The results revealed several spectacular evolutionary rearrangements between the genes present in various regions within the wheat genomes. This information will be of immense value to cereal evolutionists, and to those scientists that are using DNA sequences for wheat improvement.
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 gene-like 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 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.