title: MtQRRS1, an R-locus required for Medicago truncatula quantitative resistance to Ralstonia solanacearum.
abstract: Ralstonia solanacearum is a major soilborne pathogen that attacks > 200 plant species, including major crops. To characterize MtQRRS1, a major quantitative trait locus (QTL) for resistance towards this bacterium in the model legume Medicago truncatula, genetic and functional approaches were combined. QTL analyses together with disease scoring of heterogeneous inbred families were used to define the locus. The candidate region was studied by physical mapping using a bacterial artificial chromosome (BAC) library of the resistant line, and sequencing. In planta bacterial growth measurements, grafting experiments and gene expression analysis were performed to investigate the mechanisms by which this locus confers resistance to R. solanacearum. The MtQRRS1 locus was localized to the same position in two recombinant inbred line populations and was narrowed down to a 64 kb region. Comparison of parental line sequences revealed 15 candidate genes with sequence polymorphisms, but no evidence of differential gene expression upon infection. A role for the hypocotyl in resistance establishment was shown. These data indicate that the quantitative resistance to bacterial wilt conferred by MtQRRS1, which contains a cluster of seven R genes, is shared by different accessions and may act through intralocus interactions to promote resistance.
authors: INP, UPS, Laboratoire d'Ecologie Fonctionnelle et Environnement (Ecolab), ENSAT, Université de Toulouse, Castanet Tolosan, France.
authors: Cécile
authors: C
authors: Ben
authors: Frédéric
authors: F
authors: Debellé
authors: Hélène
authors: H
authors: Berges
authors: Arnaud
authors: A
authors: Bellec
authors: Marie-Françoise
authors: MF
authors: Jardinaud
authors: Philippe
authors: P
authors: Anson
authors: Thierry
authors: T
authors: Huguet
authors: Laurent
authors: L
authors: Gentzbittel
authors: Fabienne
authors: F
authors: Vailleau
mesh_terms: D032461:Chromosomes, Plant / Q000235:genetics; D016000:Cluster Analysis; D003433:Crosses, Genetic; D060467:Disease Resistance / Q000235:genetics*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D056726:Genetic Association Studies; D005838:Genotype; D018546:Hypocotyl / Q000276:immunology / Q000382:microbiology; D007178:Inbreeding; D046913:Medicago truncatula / Q000235:genetics* / Q000276:immunology / Q000382:microbiology*; D058977:Molecular Sequence Annotation; D008969:Molecular Sequence Data; D010641:Phenotype; D020161:Physical Chromosome Mapping; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology* / Q000382:microbiology*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D040641:Quantitative Trait Loci / Q000235:genetics*; D043368:Ralstonia solanacearum / Q000502:physiology*; D015203:Reproducibility of Results
keywords: Medicago truncatula; Ralstonia solanacearum; bacterial wilt; mapping; quantitative resistance; quantitative trait locus (QTL); root pathogen