title: Fine Mapping of the Barley Chromosome 6H Net Form Net Blotch Susceptibility Locus.
abstract: Net form net blotch, caused by the necrotrophic fungal pathogen Pyrenophora teres f. teres, is a destructive foliar disease of barley with the potential to cause significant yield loss in major production regions throughout the world. The complexity of the host-parasite genetic interactions in this pathosystem hinders the deployment of effective resistance in barley cultivars, warranting a deeper understanding of the interactions. Here, we report on the high-resolution mapping of the dominant susceptibility locus near the centromere of chromosome 6H in the barley cultivars Rika and Kombar, which are putatively targeted by necrotrophic effectors from P. teres f. teres isolates 6A and 15A, respectively. Utilization of progeny isolates derived from a cross of P. teres f. teres isolates 6A × 15A harboring single major virulence loci (VK1, VK2, and VR2) allowed for the Mendelization of single inverse gene-for-gene interactions in a high-resolution population consisting of 2976 Rika × Kombar recombinant gametes. Brachypodium distachyon synteny was exploited to develop and saturate the susceptibility region with markers, delimiting it to ∼0.24 cM and a partial physical map was constructed. This genetic and physical characterization further resolved the dominant susceptibility locus, designated Spt1 (susceptibility to P. teres f. teres). The high-resolution mapping and cosegregation of the Spt1.R and Spt1.K gene/s indicates tightly linked genes in repulsion or alleles possibly targeted by different necrotrophic effectors. Newly developed barley genomic resources greatly enhance the efficiency of positional cloning efforts in barley, as demonstrated by the Spt1 fine mapping and physical contig identification reported here.
authors.affiliation: Department of Plant Pathology, North Dakota State University, Fargo, North Dakota 58108-6050.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Richards
authors.affiliation: United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Red River Valley Agricultural Research Center, Cereal Crops Research Unit, Fargo, North Dakota, 58102-2765.
authors.forename: Shiaoman
authors.initials: S
authors.lastname: Chao
authors.affiliation: Department of Plant Pathology, North Dakota State University, Fargo, North Dakota 58108-6050 United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Red River Valley Agricultural Research Center, Cereal Crops Research Unit, Fargo, North Dakota, 58102-2765.
authors.forename: Timothy
authors.initials: T
authors.lastname: Friesen
authors.affiliation: Department of Plant Pathology, North Dakota State University, Fargo, North Dakota 58108-6050 Robert.Brueggeman@ndsu.edu.
authors.forename: Robert
authors.initials: R
authors.lastname: Brueggeman
mesh_terms: D001203:Ascomycota / Q000254:growth & development / Q000472:pathogenicity; D022202:Chromosomes, Artificial, Bacterial; D032461:Chromosomes, Plant / Q000737:chemistry* / Q000378:metabolism; D020451:Contig Mapping; D003433:Crosses, Genetic; D060467:Disease Resistance / Q000235:genetics; D004198:Disease Susceptibility / Q000276:immunology* / Q000382:microbiology; D004843:Epistasis, Genetic; D005819:Genetic Markers; D001467:Hordeum / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D054884:Host-Pathogen Interactions; D010935:Plant Diseases / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D040641:Quantitative Trait Loci; D026801:Synteny; D014774:Virulence
chemical_list: D005819:Genetic Markers
keywords: high-resolution mapping; inverse gene-for-gene; necrotrophic specialist