title: Resistance to Puccinia graminis f. sp. avenae in Barley Is Associated with the Rpg5 Locus.
abstract: In barley, gene Rpg5 was first identified for providing resistance to the rye stem rust pathogen (Puccinia graminis f. sp. secalis). A subsequent study determined that Rpg5 is required for rpg4-mediated resistance to the wheat stem rust pathogen (P. graminis f. sp. tritici) including pathotype TTKSK ("Ug99"), which poses a major threat to global wheat and barley production. Based on the effectiveness of Rpg5 against P. graminis f. sp. tritici and P. graminis f. sp. secalis, we assessed whether it also conferred resistance to the oat stem rust pathogen (P. graminis f. sp. avenae). A barley F8 recombinant inbred line (RIL) population was produced by crossing 'Q21861' (Rpg1 and Rpg5) with '73-G1' (Rpg1), which is susceptible to P. graminis f. sp. avenae, P. graminis f. sp. secalis, and some pathotypes of P. graminis f. sp. tritici. Seedling tests were performed on the F8 RIL population using Australian pathotypes of P. graminis f. sp. tritici, P. graminis f. sp. secalis, P. graminis f. sp. avenae, and a putative somatic hybrid between P. graminis f. sp. tritici and P. graminis f. sp. secalis known as the 'Scabrum' rust. Segregation in the responses to all rust isolates for the RILs was identical (50 resistant: 52 susceptible), and fitted a 1:1 ratio (X2=0.039, P=0.843), indicating that resistance to all isolates was monogenetically inherited. Screening of the RILs and the parental lines with perfect markers for the functional Rpg1 and Rpg5 resistance alleles indicated that Rpg1 was fixed, while Rpg5 was positive in all resistant lines and negative in all susceptible lines. This suggests that different formae speciales of P. graminis may share common effectors, and that the Rpg5 locus confers resistance to both P. graminis f. sp. tritici and P. graminis f. sp. secalis and the heterologous formae speciales of P. graminis, P. graminis f. sp. avenae.
authors: First, second, and fourth authors: The University of Sydney, Plant Breeding Institute Cobbitty, Private Bag 4011, Narellan, NSW, 2567, Australia; and third author: Cereal Research Centre, Agriculture & Agri-Food Canada, Winnipeg, MB, Canada.
authors: Peter
authors: P
authors: Dracatos
authors: Davinder
authors: D
authors: Singh
authors: Tom
authors: T
authors: Fetch
authors: Robert
authors: R
authors: Park
mesh_terms: D000483:Alleles; D001315:Australia; D001487:Basidiomycota / Q000502:physiology*; D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics*; D003433:Crosses, Genetic; D060467:Disease Resistance; D005819:Genetic Markers / Q000235:genetics; D005838:Genotype; D001467:Hordeum / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D010641:Phenotype; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D018515:Plant Leaves / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics*; D018547:Plant Stems / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D036226:Seedlings / Q000235:genetics / Q000276:immunology / Q000382:microbiology
chemical_list: D005819:Genetic Markers; D010940:Plant Proteins