Novel stripe rust all-stage resistance loci edentified in a worldwide collection of durum wheat using genome-wide association mapping

Authors: AOUN, MERIEM - North Dakota State University; Chen, Xianming; SOMO, MOHAMED - Cornell University; Xu, Steven; LI, XUEHUI - North Dakota State University; ELIAS, ELIAS - North Dakota State University

Submitted to: The Plant Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/24/2021
Publication Date: 11/5/2021
Citation: Aoun, M., Chen, X., Somo, M., Xu, S.S., Li, X., Elias, E.M. 2021. Novel stripe rust all-stage resistance loci edentified in a worldwide collection of durum wheat using genome-wide association mapping. The Plant Genome. 14. Article e20136. https://doi.org/10.1002/tpg2.20136.
DOI: https://doi.org/10.1002/tpg2.20136

Interpretive Summary: Durum wheat production is constrained by fungal diseases including stripe rust. Continuous mining of germplasm for the discovery and deployment of stripe rust resistance genes is needed to counter the impact of this disease. In this study, we evaluated a worldwide collection of 432 durum wheat lines to seven United States races of the wheat stripe rust pathogen that carry diverse virulence/avirulence combinations on wheat genes for resistance to stripe rust. We found that 46–84% of the durum wheat accessions were susceptible to each of the tested races. A total of 32 accessions were resistant to all seven races. Genome-wide association studies (GWAS) using over 97,000 SNP markers generated from genotyping-by-sequencing of 364 accessions identified 56 quantitative trait loci (QTL) associated with all-stage stripe rust resistance located on all 14 durum wheat chromosomes. Six of these QTL were associated with resistance to 2-4 races and none of these QTL were associated with resistance to all seven races. The remaining 50 QTL were effective against one race. Eighteen of the 56 identified QTL had large effects against at least one of the races. Map-based comparison of the discovered QTL in this study with previously published stripe rust resistance genes/QTL showed that 28 were previously identified, whereas the remaining 28 QTL appear to be novel. This study reports effective sources of stripe rust resistance to contemporary races in the United States and shows that this durum wheat collection is abundant in novel resistance loci that can be transferred into adapted durum cultivars.

Technical Abstract: Durum wheat production is constrained by fungal diseases including stripe rust caused by Puccinia striiformis f. sp. tritici (Pst). Continuous mining of germplasm for the discovery and deployment of stripe rust resistance (Yr) genes is needed to counter the impact of this disease. In this study, we evaluated a worldwide collection of 432 durum wheat lines to seven US Pst races that carry diverse virulence/avirulence combinations on wheat Yr genes. We found that 46–84% of the durum wheat accessions were susceptible to each of the tested Pst races. A total of 32 accessions were resistant to all seven races. Genome-wide association studies (GWAS) using over 97,000 SNP markers generated from genotyping-by-sequencing of 364 accessions identified 56 quantitative trait loci (QTL) associated with all-stage stripe rust resistance located on all 14 durum wheat chromosomes. Six of these QTL were associated with resistance to 2-4 Pst races and none of these QTL were associated with resistance to all seven races. The remaining 50 QTL were effective against one race. Eighteen of the 56 identified QTL had large effects against at least one of the races. Map-based comparison of the discovered QTL in this study with previously published Yr genes/QTL showed that 28 were previously identified, whereas the remaining 28 QTL appear to be novel. This study reports effective sources of stripe rust resistance to contemporary races in the United States and shows that this durum wheat collection is abundant in novel resistance loci that can be transferred into adapted durum cultivars.