Divergent evolutionary mechanisms of co-located Tak/Lrk and Glu-D3 loci revealed by comparative analysis of grass genomes

• Published in: Genome Vol. 56; no. 4; pp. 195 - 204
• Main Authors: Wang, Zi-Ning, Banik, Mitali, Cloutier, Sylvie
• Format: Journal Article
• Language: English
• Published: Canada NRC Research Press 01.04.2013; Canadian Science Publishing NRC Research Press
• Subjects: Brachypodium; Comparative analysis; densité génique; Disease resistance; Evolution; Evolution, Molecular; Evolutionary genetics; evolutionary mechanisms; gene density; Gene Duplication; Gene loci; Genetic aspects; Genetic Loci; Genome, Plant; Genomics; Glu-3; Glutens - genetics; graminées; Grasses; Hordeum vulgare; Molecular weight; Multigene Family; mécanismes évolutifs; Oryza sativa; Phylogeny; Physiological aspects; Plant immunology; Plant reproduction; Poaceae - genetics; Protein-Serine-Threonine Kinases - genetics; Quantitative genetics; Sequence Alignment; Sorghum; Tak/Lrk; Triticum aestivum; Wheat; Zea mays; United States
• ISSN: 0831-2796; 1480-3321
• DOI: 10.1139/gen-2012-0172

Seed storage and disease resistance proteins are major traits of wheat. The study of their gene organization and evolution has some implications in breeding. In this study, we characterized the hexaploid wheat D-genome BAC clone TaBAC703A9 that contains a low molecular weight glutenin locus (Glu-D3) and a resistance gene analogue cluster. With a gene density of one gene per 4.8 kb, the cluster contains four resistance gene analogues, namely Tak703-1, Lrr703, Tak703, and Lrk703. This structural cluster unit was conserved across nine grass genomes, but divergent evolutionary mechanisms have been involved in shaping the Tak/Lrk loci in the different species. Gene duplication was the major force for the Tak/Lrk evolution in oats, maize, barley, wheat, sorghum, and Brachypodium, while tandem duplication drove the expansion of this locus in japonica rice. Despite the close proximity of the Glu-D3 and the Tak/Lrk loci in wheat, the evolutionary mechanisms that drove their amplification differ. The Glu-D3 region had a lower gene density, and its amplification was driven by retroelements.