title: Effectors from Wheat Rust Fungi Suppress Multiple Plant Defense Responses.
abstract: Fungi that cause cereal rust diseases (genus Puccinia) are important pathogens of wheat globally. Upon infection, the fungus secretes a number of effector proteins. Although a large repository of putative effectors has been predicted using bioinformatic pipelines, the lack of available high-throughput effector screening systems has limited functional studies on these proteins. In this study, we mined the available transcriptomes of Puccinia graminis and P. striiformis to look for potential effectors that suppress host hypersensitive response (HR). Twenty small (<300 amino acids), secreted proteins, with no predicted functions were selected for the HR suppression assay using Nicotiana benthamiana, in which each of the proteins were transiently expressed and evaluated for their ability to suppress HR caused by four cytotoxic effector-R gene combinations (Cp/Rx, ATR13/RPP13, Rpt2/RPS-2, and GPA/RBP-1) and one mutated R gene-Pto(Y207D). Nine out of twenty proteins, designated Shr1 to Shr9 (suppressors of hypersensitive response), were found to suppress HR in N. benthamiana. These effectors varied in the effector-R gene defenses they suppressed, indicating these pathogens can interfere with a variety of host defense pathways. In addition to HR suppression, effector Shr7 also suppressed PAMP-triggered immune response triggered by flg22. Finally, delivery of Shr7 through Pseudomonas fluorescens EtHAn suppressed nonspecific HR induced by Pseudomonas syringae DC3000 in wheat, confirming its activity in a homologous system. Overall, this study provides the first evidence for the presence of effectors in Puccinia species suppressing multiple plant defense responses.
authors: First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339.
authors: Sowmya R
authors: SR
authors: Ramachandran
authors: First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339.
authors: Chuntao
authors: C
authors: Yin
authors: First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339.
authors: Joanna
authors: J
authors: Kud
authors: First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339.
authors: Kiwamu
authors: K
authors: Tanaka
authors: First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339.
authors: Aaron K
authors: AK
authors: Mahoney
authors: First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339.
authors: Fangming
authors: F
authors: Xiao
authors: First, second, fourth, fifth, and seventh authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and third and sixth authors: Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339.
authors: Scot H
authors: SH
authors: Hulbert
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001487:Basidiomycota / Q000235:genetics* / Q000502:physiology; D016923:Cell Death; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D016153:Genes, Suppressor; D054884:Host-Pathogen Interactions; D006967:Hypersensitivity; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D057865:Plant Immunity; D018515:Plant Leaves / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D030821:Plants, Genetically Modified; D011551:Pseudomonas fluorescens / Q000235:genetics / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D059467:Transcriptome; D014908:Triticum / Q000235:genetics / Q000276:immunology* / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins; D017382:Reactive Oxygen Species
keywords: reactive oxygen species