Identifying loci conferring resistance to leaf and stripe rusts in a spring wheat population (Triticum aestivum L.) via genome-wide association mapping

Authors: LIU, WEIZHEN - Washington State University; Kolmer, James; RYNEARSON, SHERI - Washington State University; Chen, Xianming; LIANGLIANG, GAO - University Of Minnesota; ANDERSON, JAMES - University Of Minnesota; TURNER, M. - University Of Minnesota; PUMPHREY, MICHAEL - Washington State University

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/30/2019
Publication Date: 10/1/2019
Citation: Liu, W., Kolmer, J.A., Rynearson, S., Chen, X., Liangliang, G., Anderson, J.A., Turner, M.K., Pumphrey, M. 2019. Identifying loci conferring resistance to leaf and stripe rusts in a spring wheat population (Triticum aestivum L.) via genome-wide association mapping. Phytopathology. 109:1932-1940. https://doi.org/10.1094/PHYTO-04-19-0143-R.
DOI: https://doi.org/10.1094/PHYTO-04-19-0143-R

Interpretive Summary: Stripe rust, caused by the fungus Puccinia striiformis f. sp. tritici, is an important disease of wheat in the USA and worldwide. To reduce yield losses in wheat due to this disease, wheat breeders add stripe rust resistance genes to wheat using molecular DNA markers that are linked to the resistance genes, and also by testing wheat cultivars with different races or biotypes of stripe rust. The objective of this study was to find molecular DNA markers that are linked to stripe rust resistance genes in wheat. A collection of spring wheat cultivars from the USA and worldwide was tested for stripe rust resistance in field plots and also with five different races. A total of 21 possible stripe rust resistance genes in this collection were found to be linked to DNA markers. Three of these genes were also closely linked to genes that give resistance to leaf rust caused by Puccinia triticina. The DNA markers linked to the stripe rust resistance genes can be used by wheat breeders to develop wheat cultivars with improved stripe rust resistance.

Technical Abstract: A genome-wide association study (GWAS) for leaf rust (caused by Puccinia triticina Erikss.) resistance identified 46 resistance quantitative trait loci (QTL) in an elite spring wheat leaf rust resistance diversity panel. Testing for stripe rust (caused by Puccinia striiformis Westend. f. sp. tritici Erikss.) responses in five US environments at the adult-plant stage and to five US races at the seedling stage revealed balanced phenotypic distributions in this population except for the seedling response to race PSTv-37. GWAS for stripe rust resistance discovered a total of 21 QTL significantly associated with all-stage or field resistance on chromosomes 1B, 1D, 2B, 3B, 4A, 5A, 5B, 5D, 6A, 6B, 7A and 7B. Previously documented pleiotropic stripe and leaf rust resistance genes Yr18/Lr34, Yr17/Lr37, Yr30/Lr27 and Yr46/Lr67 were detected in this population. In addition, stripe rust resistance QTL Yrswp-2B.1, Yrswp-3B and Yrswp-7B co-located with leaf rust resistance locus 2B_3, 3B_t2 and 7B_4, respectively. Haplotype analysis revealed that Yrswp-3B and 3B_t2 were either tightly linked or the same gene with a pleiotropic effect for resistance to both stripe and leaf rusts. The SNP markers IWB35950, IWB74350, and IWB72134 for the 3B QTL to both rusts should be useful in incorporating the resistance allele(s) in new cultivars.