title: Host-induced gene silencing in barley powdery mildew reveals a class of ribonuclease-like effectors.
abstract: Obligate biotrophic pathogens of plants must circumvent or counteract defenses to guarantee accommodation inside the host. To do so, they secrete a variety of effectors that regulate host immunity and facilitate the establishment of pathogen feeding structures called haustoria. The barley powdery mildew fungus Blumeria graminis f. sp. hordei produces a large number of proteins predicted to be secreted from haustoria. Fifty of these Blumeria effector candidates (BEC) were screened by host-induced gene silencing (HIGS), and eight were identified that contribute to infection. One shows similarity to β-1,3 glucosyltransferases, one to metallo-proteases, and two to microbial secreted ribonucleases; the remainder have no similarity to proteins of known function. Transcript abundance of all eight BEC increases dramatically in the early stages of infection and establishment of haustoria, consistent with a role in that process. Complementation analysis using silencing-insensitive synthetic cDNAs demonstrated that the ribonuclease-like BEC 1011 and 1054 are bona fide effectors that function within the plant cell. BEC1011 specifically interferes with pathogen-induced host cell death. Both are part of a gene superfamily unique to the powdery mildew fungi. Structural modeling was consistent, with BEC1054 adopting a ribonuclease-like fold, a scaffold not previously associated with effector function.
authors: Department of Life Science, Imperial College, London, UK.
authors: Clara
authors: C
authors: Pliego
authors: Daniela
authors: D
authors: Nowara
authors: Giulia
authors: G
authors: Bonciani
authors: Dana M
authors: DM
authors: Gheorghe
authors: Ruo
authors: R
authors: Xu
authors: Priyanka
authors: P
authors: Surana
authors: Ehren
authors: E
authors: Whigham
authors: Dan
authors: D
authors: Nettleton
authors: Adam J
authors: AJ
authors: Bogdanove
authors: Roger P
authors: RP
authors: Wise
authors: Patrick
authors: P
authors: Schweizer
authors: Laurence V
authors: LV
authors: Bindschedler
authors: Pietro D
authors: PD
authors: Spanu
mesh_terms: D001203:Ascomycota / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D016923:Cell Death; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D020868:Gene Silencing; D005816:Genetic Complementation Test; D001467:Hordeum / Q000382:microbiology* / Q000502:physiology; D054884:Host-Pathogen Interactions; D009154:Mutation; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology / Q000502:physiology; D018749:RNA, Plant / Q000235:genetics; D012260:Ribonucleases / Q000235:genetics* / Q000378:metabolism; D036226:Seedlings / Q000382:microbiology / Q000502:physiology; D013045:Species Specificity
chemical_list: D005656:Fungal Proteins; D018749:RNA, Plant; D012260:Ribonucleases