|LA ROTA, M|
|LAPITAN, N L|
Submitted to: Wheat Genetics International Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/30/2003
Publication Date: 9/1/2003
Citation: Dvorak, J., Akhunov, E.D., Akhunov, A.R., Luo, M., Linkiewicz, A.M., Dubcovsky, J., Hummel, D., Lazo, G.R., Chao, S., Anderson, O.D., David, J., Qi, L., Echalier, B., Gill, B.S., Miftahudin, Gustafson, J.P., La Rota, M., Sorrells, M.E., Zhang, D., Nguyen, H.T., Kalavacharla, V., Hossain, K., Kianian, S.F., Peng, J., Lapitan, N.V., Wennerlind, E.J., Nduati, V., Anderson, J.A., Sidhu, D., Gill, K.S., Choi, D., Close, T.J., Mcguire, P.E., Qualset, C.O. 2003. New insights into the organization and evolution of wheat genomes. In: Proceedings of the Wheat Genetics International Symposium, September 1-6, 2003, Paestum, Italy. p. 248-253.
Technical Abstract: Mapping genes detected by wheat expressed sequence tags (ESTs) in hexaploid wheat and an analysis of distribution and frequencies of gene deletions in tetraploid and hexaploid wheats provided new insights into the organization of wheat genomes and suggested that recombination has played a central role in their evolution. Relative gene densities and recombination rates along wheat chromosome arms were shown to increase with the relative distance from the centromere. Single-gene loci present once in each wheat genome were located predominantly in the proximal, low-recombination regions, while multi-gene loci were more frequent in distal, high-recombinational regions. The distribution of loci that originated by duplication and transposition correlated positively with recombination rates along chromosome arms. Fixed deletions of loci that occurred in diploid ancestors of wheat were also most frequent in high recombination regions. The global effect of these trends is that the distal regions of wheat chromosome arms have been evolving faster than the proximal, low-recombination regions. This is reflected by lower synteny between homoeologous chromosomes in the distal chromosome regions than in the proximal chromosome regions. Polymorphism for deletions that occurred during the evolution of tetraploid and hexaploid wheat was higher in the distal, high-recombination region than in the proximal, low-recombination region. It is suggested that this disparity in the deletion rates leads to higher gene density in the distal chromosome regions.