Genome-wide mapping of resistance to stripe rust caused by Puccinia striiformis f. sp. tritici in hexaploid winter wheat

Authors: MULETA, KEBEDE - Washington State University; Chen, Xianming; PUMPHREY, MICHAEL - Washington State University

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2019
Publication Date: 2/14/2020
Citation: Muleta, K.T., Chen, X., Pumphrey, M. 2020. Genome-wide mapping of resistance to stripe rust caused by Puccinia striiformis f. sp. tritici in hexaploid winter wheat. Crop Science. 60(1):115-131. https://doi.org/10.1002/csc2.20058.
DOI: https://doi.org/10.1002/csc2.20058

Interpretive Summary: Stripe rust is a widespread disease and major limit to wheat production worldwide. The USDA-ARS National Small Grains Collection (NSGC) has proven to be a rich source of genetic diversity to improve stripe rust resistance in wheat breeding programs. The objective of the present study was to investigate the genetic diversity and source of resistance to stripe rust in 441 accessions from the collection representing globally-sourced winter wheat germplasm, as a complement to a previous study. The genome-wide association study (GWAS) was conducted to identify loci conferring resistance to stripe rust based on phenotypic data from four field experiments and greenhouse seedling resistance screening against three races of the pathogen. A total of 5,831 informative single nucleotide polymorphism markers were used to investigate population structure, linkage disequilibrium and marker-trait associations. Our results showed 12 and 7 genomic regions significantly associated with stripe rust resistance based on field adult-plant and greenhouse seedling responses, respectively. Five of the genomic regions were mapped far from previously identified stripe rust resistance genes, indicating new resistance loci. The present study provides additional insight into the usefulness of wheat germplasm collections as an important resistance source for breeding wheat varieties with stripe rust resistance. Further work should aim at validating the identified genomic regions and the associated molecular markers to enhance their utility in marker assisted breeding.

Technical Abstract: Stripe rust, caused by the fungus Puccinia striiformis f. sp. tritici (Pst) is a widespread disease and major limit to wheat production worldwide. The USDA-ARS National Small Grains Collection (NSGC) has proven to be a rich source of genetic diversity to improve stripe rust resistance in wheat breeding programs. The objective of the present study was to investigate the genetic diversity and source of resistance to stripe rust in 441 accessions from the collection representing globally-sourced winter wheat germplasm, as a complement to a previous study. The genome-wide association study (GWAS) was conducted to identify loci conferring resistance to Pst based on phenotypic data from four field experiments and greenhouse seedling resistance screening against three races of the pathogen. A total of 5,831 informative single nucleotide polymorphism (SNP) markers were used to investigate population structure, linkage disequilibrium and marker-trait associations. Our results showed 12 and 7 genomic regions significantly associated with stripe rust resistance based on field adult-plant and greenhouse seedling responses, respectively, at False Discovery Rate (FDR) adjusted P value < 0.1. Five of the significantly associated genomic regions were mapped far from previously identified Pst resistance genes and QTL, indicating that they represent potentially new stripe rust resistance loci. The present study provides additional insight into the usefulness of wheat germplasm collections as an important resistance source that can be used to incorporate diverse resistance genes into adapted wheat cultivars. Further work should aim at validating the identified genomic regions and the associated molecular markers to enhance their utility in marker assisted breeding.