Synthesis of infectious transcripts of olive latent virus 1: genes required for RNA replication and virus movement.
Genomic RNA of olive latent virus 1 (OLV-1) contains five open reading frames (ORFs) encoding proteins of 23, 82, 8, 6 and 30 (CP) kDa. A full-length cDNA copy of OLV-1RNA was prepared and cloned in a low-copy-number vector (pMUC-19) downstream of or T7 RNA polymerase promoter. Transcripts derived from this template, denoted pMUC-OLV, were highly infectious when inoculated in local and systemic hosts and infected tissues contained virus-like particles. Genes required for replication and virus movement were mapped by site-directed and deletion mutogenesis of the pMUC-OLV. ORF1 and ORF2 mutants were not viable, suggesting that replication requires the 23 and 82 kDa proteins. The 8 and 6 kDa polypeptides were involved in cell-to-cell movement, since their absence did not interfere with RNA replication but prevented systemic infection of inoculated plants. Mutant clones in R and S domains of the CP gene could replicate, but they did not systemically infect Nicotiana benthamiana, indicating that the CP gene is required for OLV-1 long-distance translocation. Mutant clones with large deletions in the CP gene were not viable, probably due to loss of 3'-proximal sequences required for RNA replication.
Pantaleo
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Dipartimento di Protezione delle Piante, Università degli Studi, Italy.
Grieco
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Castellano
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Martelli
G P
GP
D015967:Gene Expression Regulation, Viral; D009154:Mutation; D016366:Open Reading Frames / Q000235:genetics; D010944:Plants / Q000821:virology*; D012367:RNA, Viral / Q000235:genetics; D019183:Tombusviridae / Q000502:physiology*; D014764:Viral Proteins / Q000235:genetics; D014779:Virus Replication / Q000502:physiology*
D012367:RNA, Viral; D014764:Viral Proteins