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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Cereal Crops Research » Research » Publications at this Location » Publication #304923
Title: Association mapping of seedling resistance to spot form net blotch in a worldwide collection of barley

Author
item TAMANG, PRABIN - North Dakota State University
item NEUPANE, ANJAN - North Dakota State University
item MAMIDI, SUJAN - North Dakota State University
item Friesen, Timothy
item BRUEGGEMAN, ROBERT - North Dakota State University

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/19/2014
Publication Date: 4/15/2015
Publication URL: http://handle.nal.usda.gov/10113/60699
Citation: Tamang, P., Neupane, A., Mamidi, S., Friesen, T., Brueggeman, R. 2015. Association mapping of seedling resistance to spot form net blotch in a worldwide collection of barley. Phytopathology. 105(4):500-508.

Interpretive Summary: Spot form net blotch is an important leaf disease of barley in major production regions around the world. Development of resistance to this disease has been difficult due to the lack of understanding of both pathogen virulence and barley resistance. A worldwide collection of barley consisting of 2062 barley accessions of diverse origin and genotype were evaluated at the seedling stage for resistance to four isolates of the causal pathogen (P. teres f. maculata) collected from the USA (FGO), New Zealand (NZKF2), Australia (SG1) and Denmark (DEN2.6). Of the 2062 barley accessions phenotyped, 1480 were genotyped for further association mapping analysis. Genome wide association mapping was utilized to identify and map resistance loci from the seedling disease response data. The 27 genomic regions were identified across all seven barley chromosomes. Six distinct loci were identified by the association mapping analysis that corresponded to previously characterized SFNB resistance loci. The 21 putative novel loci identified may represent a broad spectrum of resistance and or susceptibility loci. This is the first comprehensive association mapping study to characterize SFNB resistance underlying broad populations of the barley host and P. teres f maculata pathogen.

Technical Abstract: Spot form net blotch, caused by the necrotrophic fungal pathogen Pyrenophora teres f. maculata, is an important foliar disease of barley in major production regions around the world. Deployment of adequate host resistance is challenging because the virulence of P. teres f. maculata is highly variable and characterized quantitative resistances are typically ineffective against the diverse pathogen populations. A world barley core collection consisting of 2062 barley accessions of diverse origin and genotype were phenotyped at the seedling stage with four P. teres f. maculata isolates collected from the USA (FGO), New Zealand (NZKF2), Australia (SG1) and Denmark (DEN2.6). Of the 2062 barley accessions phenotyped, 1480 were genotyped with the Illumina barley iSelect chip and passed the quality controls with 5954 polymorphic markers used for further association mapping analysis. Genome wide association mapping was utilized to identify and map resistance loci from the seedling disease response data and the SNP marker data. The best among six different regression models was identified for each isolate and association analysis was performed separately for each. A total of 138 significant (-log10p-value>3.0) marker-trait associations (MTA) were detected. Using a 5 cM cutoff, a total of 10, 8, 13 and 6 loci associated with SFNB resistance were identified for the FGO, SG1, NZKF2, and DEN2.6 isolates, respectively. The 27 loci containing from 1-34 MTAs were identified on all seven barley chromosomes with one locus at 66-69 cM on chromosome 2H common to all four isolates. Six distinct loci were identified by the AM analysis that corresponded to previously characterized SFNB resistance QTL (QRpt4, QRpt6, Rpt4 and Rpt7) identified by biparental population analysis. The 21 putative novel loci identified may represent a broad spectrum of resistance and or susceptibility loci. This is the first comprehensive AM study to characterize SFNB resistance loci underlying broad populations of the barley host and P. teres f maculata pathogen.