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A single silent substitution in the genome of Apple stem grooving virus causes symptom attenuation

2003; Microbiology Society; Volume: 84; Issue: 9 Linguagem: Inglês

10.1099/vir.0.19179-0

1465-2099

Hisae Hirata, Xiaoyun Lu, Yasuyuki Yamaji, Satoshi Kagiwada, Masashi Ugaki, S. Namba,

Insect-Plant Interactions and Control

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.