The open reading frame 5A of foxtail mosaic virus is expressed in vivo and is dispensable for systemic infection

N. L. Robertson, R. French, T. J. Morris

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Infectious transcripts were successfully derived from full-length cDNA clones of foxtail mosaic potexvirus (FoMV). Full-length clones were constructed by RT-PCR whereby 5' and 3' genomic segments of 2.7 and 3.4 kb, respectively, were ligated into Bluescript II KS. The in vitro RNA transcripts were infectious to moncotyledonous (barley) and dicotyledonous (Chenopodium amaranticolor) plant species. Individual mutation studies on clones of each of the five major ORFs confirmed predicted gene function for the polymerase, TGB (triple gene block), and coat protein (CP) genes. Protoplast studies on expression of a unique open reading frame, ORF 5A, which initiates 143 nts upstream of the CP before it 'reads through' the CP, revealed that the 5A protein was produced in vivo. Mutation analysis of the 5A ORF indicated, however, that it was not required for either replication or for productive infection of plants. However, the nucleic acid sequences encoding the extended CP segment were shown to be important for CP expression. Additional mutations in 5A had no effect on FoMV replication in protoplasts but rendered the virus noninfectious to plants. A correlation with diminished CP production from both mutant clones implies that synthesis of subgenomic CP mRNA was compromised, and this limited systemic infection.

Original languageEnglish (US)
Pages (from-to)1685-1698
Number of pages14
JournalArchives of Virology
Volume145
Issue number8
DOIs
Publication statusPublished - Sep 16 2000

    Fingerprint

ASJC Scopus subject areas

  • Virology

Cite this