Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/13/2005
Publication Date: 3/14/2006
Citation: Brooks, S.A., Huang, L., Herbel, M.N., Gill, B.S., Brown-Guedira, G., Fellers, J.P. 2006. Structural variation and evolution of a defense-gene cluster in natural populations of Aegilops tauschii. Theor. Appl. Genet. 112:618-626.
Technical Abstract: Genetic mapping and sequencing of plant genomes have been useful for investigating eukaryotic chromosome structural organization. In man cases analyses have been limited in the number of representatives sampled from specific groups. The degree of intraspecific genome diversity remains in question, and it is possible that a single model genome may have limited utility for identifying genes in related members of the species or genus. Genes of particular interest for crop-plant improvement are disease resistance genes that are harbored by wild relatives of modern cultivated crops. The genes are evolutionarily dynamic and under selective pressure by a broad range of pathogenic organisms. Using resistance gene analogs as models for resistance gene evolution, intraspecific genome comparisons were made among populations of wild diploid wheat (Aegilops tauschii). We observed deletion haplotypes occurring frequently and independently in the genome, where total loss of gene complements is a common yet overlooked form of allelic variation. Haplotypes are correlated with species distribution and are without adaptive value in alternate environments. We address the consequences of deletion haplotypes on genome restructuring and resistance gene evolution.