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Title: Characterization of molecular diversity and genome-wide mapping of loci associated with resistance to stripe rust and stem rust in Ethiopian bread wheat accessions

Author
item MULETA, KEBEDE - Washington State University
item Rouse, Matthew
item RYNEARSON, SHERI - Washington State University
item Chen, Xianming
item BUTA, BEDADA - Ethiopian Institute Of Agricultural Research
item PUMPHREY, MICHAEL - Washington State University

Submitted to: BMC Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2017
Publication Date: 8/4/2017
Citation: Muleta, K.T., Rouse, M.N., Rynearson, S., Chen, X., Buta, B.G., Pumphrey, M. 2017. Characterization of molecular diversity and genome-wide mapping of loci associated with resistance to stripe rust and stem rust in Ethiopian bread wheat accessions. Biomed Central (BMC) Plant Biology. https://doi.org/10.1186/s12870-017-1082-7.
DOI: https://doi.org/10.1186/s12870-017-1082-7

Interpretive Summary: The narrow genetic basis of resistance in modern wheat cultivars and the strong selection response of pathogen populations have been responsible for periodic and devastating epidemics of the wheat rust diseases. New sources of resistance are needed to achieve durable varietal performance against changes in pathogen virulence. Here, we report a high-density molecular characterization and genome-wide association study (GWAS) of stripe rust and stem rust resistance in Ethiopian bread wheat lines based on phenotypic data from multi-environment field trials and seedling resistance screening experiments. A total of 24,281 single nucleotide polymorphism (SNP) markers filtered from the wheat 90K iSelect genotyping assay were used to survey Ethiopian germplasm for population structure, genetic diversity and marker-trait associations. We identified 15 loci significantly associated with seedling and adult plant resistance to stripe rust and also detected 9 additional genomic regions significantly associated with seedling resistance to stem rust in the Ethiopian wheat accessions. Many of the identi'ed resistance loci were mapped close to previously identi'ed rust resistance genes; however, three on the short arms of chromosomes 5AS and 7BS for stripe rust resistance and two on chromosomes 3BL and 7B for stem rust resistance may be novel. The molecular markers identified in this study should be useful in efficiently targeting the associated resistance loci in marker-assisted breeding for rust resistance in Ethiopia and other countries.

Technical Abstract: The narrow genetic basis of resistance in modern wheat cultivars and the strong selection response of pathogen populations have been responsible for periodic and devastating epidemics of the wheat rust diseases. Characterizing new sources of resistance and incorporating multiple genes into elite cultivars is the most widely accepted current mechanism to achieve durable varietal performance against changes in pathogen virulence. Here, we report a high-density molecular characterization and genome-wide association study (GWAS) of stripe rust and stem rust resistance in Ethiopian bread wheat lines based on phenotypic data from multi-environment field trials and seedling resistance screening experiments. A total of 24,281 single nucleotide polymorphism (SNP) markers filtered from the wheat 90K iSelect genotyping assay were used to survey Ethiopian germplasm for population structure, genetic diversity and marker-trait associations. Our results show 15 loci were significantly associated with seedling and adult plant resistance to stripe rust at false discovery rate (FDR)-adjusted probability (P) <0.10. GWAS also detected 9 additional genomic regions significantly associated (FDR-adjusted P <0.10) with seedling resistance to stem rust in the Ethiopian wheat accessions. Many of the identi'ed resistance loci were mapped close to previously identi'ed rust resistance genes; however, three on the short arms of chromosomes 5AS and 7BS for stripe rust resistance and two on chromosomes 3BL and 7B for stem rust resistance may be novel. The molecular markers identified in this study should be useful in efficiently targeting the associated resistance loci in marker-assisted breeding for rust resistance in Ethiopia and other countries.