title: QTL identification and microphenotype characterisation of the developmentally regulated yellow rust resistance in the UK wheat cultivar Guardian.
abstract: Yellow rust (causal agent: Puccinia striiformis f.sp. tritici) resistance in the UK wheat cultivar Guardian is developmentally regulated, resistance increasing as the plant matures. Yellow rust resistance was assessed under field conditions on plants after ear emergence to ensure maximum expression of resistance. Three quantitative trait loci (QTL) for yellow rust resistance were identified, being located on chromosomes 1B (QPst.jic-1B), 2D (QPst.jic-2D) and 4B (QPst.jic-4B). The largest resistance effect, QPst.jic-1B located to the same position on the long arm of chromosome 1B as the known durable source of yellow rust resistance, Yr29. Microscopic studies were carried out to determine what effect the resistance in Guardian had on the development of P. striiformis f.sp. tritici. While the adult plant resistance in Guardian did not prevent germinated urediniospores from establishing an effective infection site, the growth of hyphae within flag leaf tissue was significantly inhibited, slowing the development of microcolonies. 3,3-diaminabenzadine (DAB) and trypan blue staining indicated that this inhibition of hyphal growth was not associated with hydrogen peroxide accumulation or extensive plant cell death.
authors.affiliation: Department of Disease and Stress Biology, John Innes Centre, Norwich Research Park, Norwich, UK.
authors.forename: J P E
authors.initials: JP
authors.lastname: Melichar
authors.forename: S
authors.initials: S
authors.lastname: Berry
authors.forename: C
authors.initials: C
authors.lastname: Newell
authors.forename: R
authors.initials: R
authors.lastname: MacCormack
authors.forename: L A
authors.initials: LA
authors.lastname: Boyd
mesh_terms: D000704:Analysis of Variance; D001487:Basidiomycota / Q000166:cytology / Q000254:growth & development; D002874:Chromosome Mapping; D020090:Chromosome Segregation; D003433:Crosses, Genetic; D018525:Germination; D007113:Immunity, Innate / Q000235:genetics*; D008126:Lod Score; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics* / Q000276:immunology* / Q000382:microbiology; D040641:Quantitative Trait Loci / Q000235:genetics*; D019655:Quantitative Trait, Heritable; D013172:Spores, Fungal / Q000166:cytology / Q000502:physiology; D014908:Triticum / Q000235:genetics / Q000254:growth & development* / Q000276:immunology / Q000382:microbiology*; D006113:United Kingdom