title: Phytophthora effector targets a novel component of small RNA pathway in plants to promote infection.
abstract: A broad range of parasites rely on the functions of effector proteins to subvert host immune response and facilitate disease development. The notorious Phytophthora pathogens evolved effectors with RNA silencing suppression activity to promote infection in plant hosts. Here we report that the Phytophthora Suppressor of RNA Silencing 1 (PSR1) can bind to an evolutionarily conserved nuclear protein containing the aspartate-glutamate-alanine-histidine-box RNA helicase domain in plants. This protein, designated PSR1-Interacting Protein 1 (PINP1), regulates the accumulation of both microRNAs and endogenous small interfering RNAs in Arabidopsis. A null mutation of PINP1 causes embryonic lethality, and silencing of PINP1 leads to developmental defects and hypersusceptibility to Phytophthora infection. These phenotypes are reminiscent of transgenic plants expressing PSR1, supporting PINP1 as a direct virulence target of PSR1. We further demonstrate that the localization of the Dicer-like 1 protein complex is impaired in the nucleus of PINP1-silenced or PSR1-expressing cells, indicating that PINP1 may facilitate small RNA processing by affecting the assembly of dicing complexes. A similar function of PINP1 homologous genes in development and immunity was also observed in Nicotiana benthamiana. These findings highlight PINP1 as a previously unidentified component of RNA silencing that regulates distinct classes of small RNAs in plants. Importantly, Phytophthora has evolved effectors to target PINP1 in order to promote infection.
authors.affiliation: Department of Plant Pathology and Microbiology and Center for Plant Cell Biology, University of California, Riverside, CA 92521; and National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Yongli
authors.initials: Y
authors.lastname: Qiao
authors.affiliation: Department of Plant Pathology and Microbiology and Center for Plant Cell Biology, University of California, Riverside, CA 92521; and.
authors.forename: Jinxia
authors.initials: J
authors.lastname: Shi
authors.affiliation: Department of Plant Pathology and Microbiology and.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhai
authors.affiliation: Department of Plant Pathology and Microbiology and Center for Plant Cell Biology, University of California, Riverside, CA 92521; and.
authors.forename: Yingnan
authors.initials: Y
authors.lastname: Hou
authors.affiliation: Department of Plant Pathology and Microbiology and Center for Plant Cell Biology, University of California, Riverside, CA 92521; and wenbo.ma@ucr.edu.
authors.forename: Wenbo
authors.initials: W
authors.lastname: Ma
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000235:genetics* / Q000469:parasitology*; D002467:Cell Nucleus / Q000378:metabolism; D020868:Gene Silencing; D035683:MicroRNAs / Q000378:metabolism; D010641:Phenotype; D010838:Phytophthora / Q000378:metabolism*; D010935:Plant Diseases / Q000469:parasitology; D030821:Plants, Genetically Modified; D017434:Protein Structure, Tertiary; D020365:RNA Helicases / Q000378:metabolism; D034622:RNA Interference; D018749:RNA, Plant / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics*; D014026:Nicotiana / Q000378:metabolism; D014774:Virulence
chemical_list: D035683:MicroRNAs; D018749:RNA, Plant; D034741:RNA, Small Interfering; D020365:RNA Helicases
keywords: Phytophthora pathogenesis; RNA helicase; RxLR effector; gene silencing; small RNA