title: RXLR and CRN Effectors from the Sunflower Downy Mildew PathogenPlasmopara halstediiInduce Hypersensitive-Like Responses in Resistant Sunflower Lines.
abstract: Plasmopara halstediiis an obligate biotrophic oomycete causing downy mildew disease on sunflower,Helianthus annuus, an economically important oil crop. Severe symptoms of the disease (e.g., plant dwarfism, leaf bleaching, sporulation and production of infertile flower) strongly impair seed yield.Plresistance genes conferring resistance to specificP. halstediipathotypes were located on sunflower genetic map but yet not cloned. They are present in cultivated lines to protect them against downy mildew disease. Among the 16 differentP. halstediipathotypes recorded in France, pathotype 710 is frequently found, and therefore continuously controlled in sunflower by differentPlgenes. High-throughput sequencing of cDNA fromP. halstediiled us to identify potential effectors with the characteristic RXLR or CRN motifs described in other oomycetes. Expression of sixP. halstediiputative effectors, five RXLR and one CRN, was analyzed by qRT-PCR in pathogen spores and in the pathogen infecting sunflower leaves and selected for functional analyses. We developed a new method for transient expression in sunflower plant leaves and showed for the first time subcellular localization ofP. halstediieffectors fused to a fluorescent protein in sunflower leaf cells. Overexpression of the CRN and of 3 RXLR effectors induced hypersensitive-like cell death reactions in some sunflower near-isogenic lines resistant to pathotype 710 and not in susceptible corresponding lines, suggesting they could be involved inPlloci-mediated resistances.
authors.affiliation: Laboratoire des Interactions Plantes Microorganismes, INRA, CNRS, Université de Toulouse Castanet Tolosan, France.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Gascuel
authors.affiliation: Laboratoire des Interactions Plantes Microorganismes, INRA, CNRS, Université de Toulouse Castanet Tolosan, France.
authors.forename: Luis
authors.initials: L
authors.lastname: Buendia
authors.affiliation: Laboratoire des Interactions Plantes Microorganismes, INRA, CNRS, Université de Toulouse Castanet Tolosan, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Pecrix
authors.affiliation: Laboratoire des Interactions Plantes Microorganismes, INRA, CNRS, Université de Toulouse Castanet Tolosan, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Blanchet
authors.affiliation: Laboratoire des Interactions Plantes Microorganismes, INRA, CNRS, Université de Toulouse Castanet Tolosan, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Muños
authors.affiliation: INRA, UMR1095 Clermont-Ferrand, France.
authors.forename: Felicity
authors.initials: F
authors.lastname: Vear
authors.affiliation: Laboratoire des Interactions Plantes Microorganismes, INRA, CNRS, Université de Toulouse Castanet Tolosan, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Godiard
keywords: Agrobacterium-mediated transient expression; Plasmopara halstedii; downy mildew; hypersensitive response; oomycete effectors; resistant sunflower; subcellular localization