title: Identification of a Differentially Expressed TIR-NBS-LRR Gene in a Major QTL Associated to Leaf Rust Resistance in Salix.
abstract: An earlier identified major quantitative trait locus for resistance towards the willow leaf rust fungus Melampsora larici-epitea in a Salix viminalis x (S. viminalis × S. schwerinii) population was used to identify potential resistance genes to the rust pathogen. Screening a genomic bacterial artificial chromosome library with markers from the peak position of the QTL region revealed one gene with TIR-NBS-LRR (Toll Interleukin1 Receptor-Nucleotide Binding Site-Leucine-Rich Repeat) domain structure indicative of a resistance gene. The resistance gene analog was denoted RGA1 and further analysis revealed a number of non-synonymous single nucleotide polymorphisms in the LRR domain between the resistant and susceptible Salix genotypes. Gene expression levels under controlled conditions showed a significantly lower constitutive expression of RGA1 in the susceptible genotype. In addition, the susceptible genotype showed a significantly reduced expression level of the RGA1 gene at 24 hours post inoculation with M. larici-epitea. This indicates that the pathogen may actively suppress RGA1 gene expression allowing a compatible plant-pathogen interaction and causing infection.
authors.affiliation: Department of Plant Biology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Tom
authors.initials: T
authors.lastname: Martin
authors.affiliation: Department of Plant Biology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Ann-Christin
authors.initials: AC
authors.lastname: Rönnberg-Wästljung
authors.affiliation: Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Stenlid
authors.affiliation: Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Berit
authors.identifier: http://orcid.org/0000-0002-6456-6121
authors.initials: B
authors.lastname: Samils
mesh_terms: D000595:Amino Acid Sequence; D001487:Basidiomycota / Q000472:pathogenicity; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics / Q000378:metabolism; D060467:Disease Resistance / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D018515:Plant Leaves / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020641:Polymorphism, Single Nucleotide; D017434:Protein Structure, Tertiary; D040641:Quantitative Trait Loci; D032108:Salix / Q000235:genetics* / Q000382:microbiology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D051194:Toll-Like Receptor 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D051194:Toll-Like Receptor 1