title: A single silent substitution in the genome of Apple stem grooving virus causes symptom attenuation.
abstract: Among randomly mutagenized clones derived from an infectious cDNA copy of genomic RNA of Apple stem grooving virus (ASGV), we previously identified a clone, pRM21, whose in vitro transcript (ASGV-RM21) does not induce any symptoms characteristic of the original (wild-type) cDNA clone (ASGV-wt) in several host plants. Interestingly, ASGV-RM21 has only a single, translationally silent nucleotide substitution, U to C, at nucleotide 4646 of the viral genome within open reading frame (ORF) 1. Here, we characterize and verify this unprecedented silent-mutation-induced attenuation of symptoms in infected plants. Northern and Western blot analyses showed that less ASGV-RM21 accumulates in host plants than ASGV-wt. In addition, two more silent substitutions, U to A and U to G, constructed by site-directed mutagenesis at the same nucleotide (4646), also induced attenuated symptoms. This is the first report that a single silent substitution attenuates virus-infection symptoms and implicates a novel determinant of disease symptom severity.
authors.affiliation: Laboratory of Bioresource Technology, Graduate School of Frontier Sciences, The University of Tokyo, 202 Bioscience Bldg, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
authors.forename: Hisae
authors.initials: H
authors.lastname: Hirata
authors.affiliation: Laboratory of Bioresource Technology, Graduate School of Frontier Sciences, The University of Tokyo, 202 Bioscience Bldg, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Lu
authors.affiliation: Laboratory of Bioresource Technology, Graduate School of Frontier Sciences, The University of Tokyo, 202 Bioscience Bldg, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamaji
authors.affiliation: Laboratory of Bioresource Technology, Graduate School of Frontier Sciences, The University of Tokyo, 202 Bioscience Bldg, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kagiwada
authors.affiliation: Laboratory of Bioresource Technology, Graduate School of Frontier Sciences, The University of Tokyo, 202 Bioscience Bldg, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Ugaki
authors.affiliation: Laboratory of Bioresource Technology, Graduate School of Frontier Sciences, The University of Tokyo, 202 Bioscience Bldg, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
authors.forename: Shigetou
authors.initials: S
authors.lastname: Namba
mesh_terms: D015152:Blotting, Northern; D015153:Blotting, Western; D036022:Capsid Proteins / Q000032:analysis; D016679:Genome, Viral; D009154:Mutation; D016366:Open Reading Frames; D010935:Plant Diseases / Q000821:virology*; D018515:Plant Leaves / Q000821:virology; D010942:Plant Viruses / Q000235:genetics* / Q000302:isolation & purification; D012328:RNA Viruses / Q000235:genetics* / Q000302:isolation & purification; D012367:RNA, Viral / Q000032:analysis
chemical_list: D036022:Capsid Proteins; D012367:RNA, Viral