|OLIVERA, PABLO - University Of Minnesota
|POLAND, JESSE - Kansas State University
|Rouse, Matthew - Matt
Submitted to: BMC Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2016
Publication Date: 12/15/2016
Citation: Edae, E.A., Olivera, P., Jin, Y., Poland, J.A., Rouse, M.N. 2016. Genotype-by-sequencing facilitates genetic mapping of a stem rust resistance locus in Aegilops umbellulata, a wild relative of cultivated wheat. Biomed Central (BMC) Genomics. 17:1039. doi 10.1186/s12864-016-3370-2.
Interpretive Summary: Stem rust is a devastating fungal disease of wheat. Emerging strains of the wheat stem rust fungus such as Ug99 threaten wheat production because of their broad virulence to currently grown wheat varieties. Several accessions of a wild relative of wheat, Aegilops umbellulata are resistant to Ug99. A population derived from a Ug99-resistant Ae. umbellulata accession crossed to a Ug99-susceptible accession was created. Genetic mapping with SNP markers obtained by genotyping-by-sequencing placed resistance to Ug99 on chromosome 2U. Markers were identified as closely linked to the Ug99 resistance resistance gene in Ae. umbellulata. Scientists could use these markers to aid the introgression of this Ug99 resistance gene into wheat and for marker-assisted selection in breeding and germplasm development programs. In addition, breeders could use these markers in their breeding programs to develop Ug99 resistant wheat cultivars.
Technical Abstract: Background: Wild relatives of wheat play a significant role in wheat improvement as a source of genetic diversity. Stem rust disease of wheat causes significant yield losses at the global level and stem rust pathogen race TTKSK (Ug99) is virulent to most previously deployed resistance genes. Therefore, the objective of this study was to identify loci conferring resistance to stem rust pathogen races including Ug99 in an Aegilops umbelluata bi-parental mapping population using genotype-by-sequencing (GBS) SNP markers. Results: A bi-parental F2:3 population derived from a cross made between stem rust resistant accession PI 298905 and stem rust susceptible accession PI 542369 was used for this study. F2 individuals were evaluated with stem rust race TTTTF followed by testing F2:3 families with races TTTTF and TTKSK. The segregation pattern of resistance to both stem rust races suggested the presence of one resistance gene. A genetic linkage map, comprised 1,933 SNP markers, was created for all seven chromosomes of Ae. umbellulata using GBS. A major stem rust resistance QTL that explained 80% and 52% of the phenotypic variations for TTTTF and TTKSK, respectively, was detected on chromosome 2U of Ae. umbellulata. Conclusion: The novel resistance gene for stem rust identified in this study can be transferred to commercial wheat varieties assisted by the tightly linked markers identified here. These markers identified through our mapping approach can be a useful strategy to identify and track the resistance gene in marker-assisted breeding in wheat.