title: Infection assays in Arabidopsis reveal candidate effectors from the poplar rust fungus that promote susceptibility to bacteria and oomycete pathogens.
abstract: Fungi of the Pucciniales order cause rust diseases which, altogether, affect thousands of plant species worldwide and pose a major threat to several crops. How rust effectors-virulence proteins delivered into infected tissues to modulate host functions-contribute to pathogen virulence remains poorly understood. Melampsora larici-populina is a devastating and widespread rust pathogen of poplar, and its genome encodes 1184 identified small secreted proteins that could potentially act as effectors. Here, following specific criteria, we selected 16 candidate effector proteins and characterized their virulence activities and subcellular localizations in the leaf cells of Arabidopsis thaliana. Infection assays using bacterial (Pseudomonas syringae) and oomycete (Hyaloperonospora arabidopsidis) pathogens revealed subsets of candidate effectors that enhanced or decreased pathogen leaf colonization. Confocal imaging of green fluorescent protein-tagged candidate effectors constitutively expressed in stable transgenic plants revealed that some protein fusions specifically accumulate in nuclei, chloroplasts, plasmodesmata and punctate cytosolic structures. Altogether, our analysis suggests that rust fungal candidate effectors target distinct cellular components in host cells to promote parasitic growth.
authors.affiliation: Department of Chemistry, Biochemistry and Physics, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada, G9A 5H7.|Canadian Forest Service, Laurentian Forestry Centre, Natural Resources Canada, Sainte-Foy, QC, Canada, G1V 4C7.
authors.forename: Hugo
authors.initials: H
authors.lastname: Germain
authors.affiliation: Département de Biologie, Université de Moncton, Moncton, NB, Canada, E1A 3E9.
authors.forename: David L
authors.initials: DL
authors.lastname: Joly
authors.affiliation: Department of Chemistry, Biochemistry and Physics, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada, G9A 5H7.
authors.forename: Caroline
authors.initials: C
authors.lastname: Mireault
authors.affiliation: Department of Chemistry, Biochemistry and Physics, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada, G9A 5H7.
authors.forename: Mélodie B
authors.initials: MB
authors.lastname: Plourde
authors.affiliation: Department of Chemistry, Biochemistry and Physics, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada, G9A 5H7.
authors.forename: Claire
authors.initials: C
authors.lastname: Letanneur
authors.affiliation: Canadian Forest Service, Laurentian Forestry Centre, Natural Resources Canada, Sainte-Foy, QC, Canada, G1V 4C7.
authors.forename: Donald
authors.initials: D
authors.lastname: Stewart
authors.affiliation: Canadian Forest Service, Laurentian Forestry Centre, Natural Resources Canada, Sainte-Foy, QC, Canada, G1V 4C7.
authors.forename: Marie-Josée
authors.initials: MJ
authors.lastname: Morency
authors.affiliation: The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK.|Centre INRA Nancy Lorraine, INRA, UMR 1136 Interactions Arbres/Microorganismes, INRA/Université de Lorraine, Champenoux, 54280, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Petre
authors.affiliation: Centre INRA Nancy Lorraine, INRA, UMR 1136 Interactions Arbres/Microorganismes, INRA/Université de Lorraine, Champenoux, 54280, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Duplessis
authors.affiliation: Canadian Forest Service, Laurentian Forestry Centre, Natural Resources Canada, Sainte-Foy, QC, Canada, G1V 4C7.
authors.forename: Armand
authors.initials: A
authors.lastname: Séguin
mesh_terms: D017360:Arabidopsis / Q000382:microbiology*; D001487:Basidiomycota / Q000472:pathogenicity*; D001681:Biological Assay; D002736:Chloroplasts / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism*; D009868:Oomycetes / Q000254:growth & development / Q000472:pathogenicity*; D000069452:Pathogen-Associated Molecular Pattern Molecules / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology*; D057865:Plant Immunity; D030821:Plants, Genetically Modified; D031425:Plasmodesmata / Q000378:metabolism; D032107:Populus / Q000382:microbiology*; D044224:Pseudomonas syringae / Q000254:growth & development / Q000472:pathogenicity*; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D000069452:Pathogen-Associated Molecular Pattern Molecules
keywords: confocal microscopy; fungus; obligate biotroph; parasite; virulence assays