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Title: Genome-wide association mapping reveals a rich genetic architecture of stripe rust resistance loci in emmer wheat (Triticum turgidum ssp. dicoccum)

Author
item LIU, WEIZHEN - Washington State University
item MACCAFERRI, MARCO - University Of Bologna, Italy
item Chen, Xianming
item PUMPHREY, MICHAEL - Washington State University
item LAGHETTI, GAETANO - Istituto Di Bioscienze E Biorisorse-Uos Portici-cnr
item PIGNONE, DOMENICO - Istituto Di Bioscienze E Biorisorse-Uos Portici-cnr
item TUBEROSA, ROBERTO - University Of Bologna, Italy

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2017
Publication Date: 11/20/2017
Citation: Liu, W., Maccaferri, M., Chen, X., Pumphrey, M., Laghetti, G., Pignone, D., Tuberosa, R. 2017. Genome-wide association mapping reveals a rich genetic architecture of stripe rust resistance loci in emmer wheat (Triticum turgidum ssp. dicoccum). Theoretical and Applied Genetics. 130(11):2249-2270.

Interpretive Summary: Cultivated emmer wheat, one of the oldest domesticated crops in the world, is a potentially rich reservoir of variation for improvement of resistance/tolerance to biotic and abiotic stresses in wheat. Here, we employed genome-wide association (GWAS) mapping to dissect effective stripe rust resistance loci in a worldwide collection of 176 cultivated emmer wheat accessions. Adult plants were tested in six field environments and seedlings were evaluated with five races of the pathogen from the United States and one race from Italy under greenhouse conditions. Five accessions were resistant across all experiments. The panel was genotyped with the wheat 90,000 Illumina iSelect single nucleotide polymorphism (SNP) array and 5,106 polymorphic SNP markers with mapped positions were obtained. A high level of genetic diversity and fast linkage disequilibrium decay were observed. In total, we identified 14 loci associated with field resistance in multiple environments. Thirty-seven loci were significantly associated with all-stage (seedling) resistance and six of them were effective to multiple races. Of the 51 loci, 29 were mapped distantly from previously reported stripe rust resistance genes or quantitative trait loci and represent newly documented resistance loci. Our results suggest that GWAS is an effective method for characterizing genes in cultivated emmer wheat and confirm that emmer wheat is a rich source of stripe rust resistance loci that could be used for durum and bread wheat improvement.

Technical Abstract: Cultivated emmer wheat (Triticum turgidum ssp. dicoccum), one of the oldest domesticated crops in the world, is a potentially rich reservoir of variation for improvement of resistance/tolerance to biotic and abiotic stresses in wheat. Resistance to stripe rust (Puccinia striiformis f. sp. tritici) in emmer wheat has been under-investigated. Here, we employed genome-wide association mapping to dissect effective stripe rust resistance loci in a worldwide collection of 176 cultivated emmer wheat accessions. Adult plants were tested in six environments and seedlings were evaluated with five races of the pathogen from the United States and one race from Italy under greenhouse conditions. Five accessions were resistant across all experiments. The panel was genotyped with the wheat 90,000 Illumina iSelect single nucleotide polymorphism (SNP) array and 5,106 polymorphic SNP markers with mapped positions were obtained. A high level of genetic diversity and fast linkage disequilibrium decay were observed. In total, we identified 14 loci associated with field resistance in multiple environments. Thirty-seven loci were significantly associated with all-stage (seedling) resistance and six of them were effective to multiple races. Of the 51 loci, 29 were mapped distantly from previously reported stripe rust resistance genes or quantitative trait loci and represent newly documented resistance loci. Our results suggest that GWAS is an effective method for characterizing genes in cultivated emmer wheat and confirm that emmer wheat is a rich source of stripe rust resistance loci that could be used for durum and bread wheat improvement.