title: EXA1, a GYF domain protein, is responsible for loss-of-susceptibility to plantago asiatica mosaic virus in Arabidopsis thaliana.
abstract: One of the plant host resistance machineries to viruses is attributed to recessive alleles of genes encoding critical host factors for virus infection. This type of resistance, also referred to as recessive resistance, is useful for revealing plant-virus interactions and for breeding antivirus resistance in crop plants. Therefore, it is important to identify a novel host factor responsible for robust recessive resistance to plant viruses. Here, we identified a mutant from an ethylmethane sulfonate (EMS)-mutagenized Arabidopsis population which confers resistance to plantago asiatica mosaic virus (PlAMV, genus Potexvirus). Based on map-based cloning and single nucleotide polymorphism analysis, we identified a premature termination codon in a functionally unknown gene containing a GYF domain, which binds to proline-rich sequences in eukaryotes. Complementation analyses and robust resistance to PlAMV in a T-DNA mutant demonstrated that this gene, named Essential for poteXvirus Accumulation 1 (EXA1), is indispensable for PlAMV infection. EXA1 contains a GYF domain and a conserved motif for interaction with eukaryotic translation initiation factor 4E (eIF4E), and is highly conserved among monocot and dicot species. Analysis using qRT-PCR and immunoblotting revealed that EXA1 was expressed in all tissues, and was not transcriptionally responsive to PlAMV infection in Arabidopsis plants. Moreover, accumulation of PlAMV and a PlAMV-derived replicon was drastically diminished in the initially infected cells by the EXA1 deficiency. Accumulation of two other potexviruses also decreased in exa1-1 mutant plants. Our results provided a functional annotation to GYF domain-containing proteins by revealing the function of the highly conserved EXA1 gene in plant-virus interactions.
authors.affiliation: Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Hashimoto
authors.affiliation: Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Yutaro
authors.initials: Y
authors.lastname: Neriya
authors.affiliation: Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Keima
authors.affiliation: Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Nozomu
authors.initials: N
authors.lastname: Iwabuchi
authors.affiliation: Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Koinuma
authors.affiliation: Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Hagiwara-Komoda
authors.affiliation: Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ishikawa
authors.affiliation: Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Misako
authors.initials: M
authors.lastname: Himeno
authors.affiliation: Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Kensaku
authors.initials: K
authors.lastname: Maejima
authors.affiliation: Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamaji
authors.affiliation: Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan. anamba@mail.ecc.u-tokyo.ac.jp.
authors.forename: Shigetou
authors.initials: S
authors.lastname: Namba
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000821:virology*; D010935:Plant Diseases / Q000235:genetics / Q000821:virology*; D010942:Plant Viruses / Q000472:pathogenicity*
keywords: 
  Arabidopsis thaliana
  ; 
  Potexvirus
  ; EXA1; GYF domain; plant-virus interactions; plantago asiatica mosaic virus; recessive resistance