title: Effector Polymorphisms of the Sunflower Downy Mildew Pathogen Plasmopara halstedii and Their Use to Identify Pathotypes from Field Isolates.
abstract: The obligate biotroph oomycete Plasmopara halstedii causes downy mildew on sunflower crop, Helianthus annuus. The breakdown of several Pl resistance genes used in sunflower hybrids over the last 25 years came along with the appearance of new Pl. halstedii isolates showing modified virulence profiles. In oomycetes, two classes of effector proteins, key players of pathogen virulence, are translocated into the host: RXLR and CRN effectors. We identified 54 putative CRN or RXLR effector genes from transcriptomic data and analyzed their genetic diversity in seven Pl. halstedii pathotypes representative of the species variability. Pl. halstedii effector genes were on average more polymorphic at both the nucleic and protein levels than random non-effector genes, suggesting a potential adaptive dynamics of pathogen virulence over the last 25 years. Twenty-two KASP (Competitive Allele Specific PCR) markers designed on polymorphic effector genes were genotyped on 35 isolates belonging to 14 Pl. halstedii pathotypes. Polymorphism analysis based on eight KASP markers aims at proposing a determination key suitable to classify the eight multi-isolate pathotypes into six groups. This is the first report of a molecular marker set able to discriminate Pl. halstedii pathotypes based on the polymorphism of pathogenicity effectors. Compared to phenotypic tests handling living spores used until now to discriminate Pl. halstedii pathotypes, this set of molecular markers constitutes a first step in faster pathotype diagnosis of Pl. halstedii isolates. Hence, emerging sunflower downy mildew isolates could be more rapidly characterized and thus, assessment of plant resistance breakdown under field conditions should be improved.
authors: Institut National de la Recherche Agronomique, INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), Unité Mixte de Recherches UMR441, F-31326 Castanet-Tolosan, France.|Centre National de la Recherche Scientifique, CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), Unité Mixte de Recherches UMR2594, F-31326 Castanet-Tolosan, France.
authors: Quentin
authors: Q
authors: Gascuel
authors: Institut National de la Recherche Agronomique, INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), Unité Mixte de Recherches UMR441, F-31326 Castanet-Tolosan, France.|Centre National de la Recherche Scientifique, CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), Unité Mixte de Recherches UMR2594, F-31326 Castanet-Tolosan, France.
authors: Amandine
authors: A
authors: Bordat
authors: Institut National de la Recherche Agronomique, INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), Unité Mixte de Recherches UMR441, F-31326 Castanet-Tolosan, France.|Centre National de la Recherche Scientifique, CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), Unité Mixte de Recherches UMR2594, F-31326 Castanet-Tolosan, France.
authors: Erika
authors: E
authors: Sallet
authors: Institut National de la Recherche Agronomique, INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), Unité Mixte de Recherches UMR441, F-31326 Castanet-Tolosan, France.|Centre National de la Recherche Scientifique, CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), Unité Mixte de Recherches UMR2594, F-31326 Castanet-Tolosan, France.
authors: Nicolas
authors: N
authors: Pouilly
authors: Institut National de la Recherche Agronomique, INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), Unité Mixte de Recherches UMR441, F-31326 Castanet-Tolosan, France.|Centre National de la Recherche Scientifique, CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), Unité Mixte de Recherches UMR2594, F-31326 Castanet-Tolosan, France.
authors: Sébastien
authors: S
authors: Carrere
authors: Institut National de la Recherche Agronomique, INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), Unité Mixte de Recherches UMR441, F-31326 Castanet-Tolosan, France.|Centre National de la Recherche Scientifique, CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), Unité Mixte de Recherches UMR2594, F-31326 Castanet-Tolosan, France.
authors: Fabrice
authors: F
authors: Roux
authors: Institut National de la Recherche Agronomique, INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), Unité Mixte de Recherches UMR441, F-31326 Castanet-Tolosan, France.|Centre National de la Recherche Scientifique, CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), Unité Mixte de Recherches UMR2594, F-31326 Castanet-Tolosan, France.
authors: Patrick
authors: P
authors: Vincourt
authors: Institut National de la Recherche Agronomique, INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), Unité Mixte de Recherches UMR441, F-31326 Castanet-Tolosan, France.|Centre National de la Recherche Scientifique, CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), Unité Mixte de Recherches UMR2594, F-31326 Castanet-Tolosan, France.
authors: Laurence
authors: L
authors: Godiard
mesh_terms: D000483:Alleles; D005819:Genetic Markers; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006368:Helianthus / Q000382:microbiology*; D009868:Oomycetes / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D010935:Plant Diseases / Q000382:microbiology; D011110:Polymorphism, Genetic; D020641:Polymorphism, Single Nucleotide; D014774:Virulence / Q000235:genetics
chemical_list: D005819:Genetic Markers