EXA1, a GYF domain protein, is responsible for loss‐of‐susceptibility to plantago asiatica mosaic virus in Arabidopsis thaliana. (19th September 2016)

• Record Type: Journal Article
• Authors: Hashimoto, Masayoshi; Neriya, Yutaro; Keima, Takuya; Iwabuchi, Nozomu; Koinuma, Hiroaki; Hagiwara‐Komoda, Yuka; Ishikawa, Kazuya; Himeno, Misako; Maejima, Kensaku; Yamaji, Yasuyuki; Namba, Shigetou
• Is Part Of: Plant journal. Volume 88:Number 1(2016:Oct.)
• Page Start: 120
• Page End: 131
• Publication Date: 2016-09-19
• Subjects: recessive resistance -- EXA1 -- plantago asiatica mosaic virus -- Potexvirus -- GYF domain -- Arabidopsis thaliana -- plant–virus interactions; Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.13265
• Languages: English
• ISSNs: 0960-7412

Abstract

Summary: 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. Significance Statement: Plant host resistance to viruses can be mediated by dominant disease resistance (R) genes or by recessive alleles of genes encoding host factors that are critical for viral infection. Recessive resistance has been used to breed for virus‐resistant plants as well as for understanding plant‐virus interactions. Here we identified a host factor that is highly conserved among monocot and dicot species, and is critical for accumulation of three related, but distinct plant RNA viruses.