Plant virus-specific transport function I. Virus genetic control required for systemic spread

SUMMARY B component RNA (B-RNA) of red clover mottle comovirus (RCMV) was not transported between cells of inoculated leaf tissue unless it was co-inoculated with the M component. However when host plants were infected with sunn-hemp mosaic tobamovirus (SHMV) or mutant Nill8 of tobacco mosaic virus (TMV) before superinoculation, RCMV B-RNA was transported readily between cells. Plants were infected with SHMV or Nill8 and, 5 days after superinoculation with RCMV B component, protoplasts were isolated from the infected leaves and inoculated with RCMV M component. About 30% of such protoplasts multiplied RCMV (identified by immunofluorescence microscopy) whereas only 3 to 5 % of protoplasts from similarly treated plants not initially infected with SHMV or Nil 18 multiplied RCMV. Thus B-RNA spread from mixedly infected (SHMV + B-RNA or Nil 18 + B-RNA) cells in the absence of M-RNA to the neighbouring cells. RCMV B-RNA spread in leaves infected with the temperature-sensitive coat protein TMV mutant Nil 18 and grown at nonpermissive temperature. Thus TMV coat protein is not involved in enabling RCMV RNA to be transported.

Section: Discussionsupporting

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Red Clover Mottle Comovirus B-RNA Spreads between Cells in Tobamovirus-infected Tissues

Malyshenko

Lapchic

Кондакова

et al. 1988

“…Previous work with the LS1 strain of tobacco mosaic virus, which is temperature-sensitive with respect to movement, has quite elegantly shown that this function is mediated by a 30K non-structural protein (Ohno et al, 1983;Meshi et al, 1987). The 30K protein function could be complemented in trans by previous inoculation with PVX (Taliansky et al, 1982). Given the significant sequence homologies observed between the 7K, 12K and 25K proteins of PVS and PVX, it would be of interest to know if PVS could also serve to complement the movement of LS1 at the restrictive temperature.…”

Section: Discussionmentioning

confidence: 74%

Organization and Interviral Homologies of the 3'-terminal Portion of Potato Virus S RNA

MacKenzie¹,

Tremaine²,

Stace-Smith³

1989

SUMMARYThe sequence of 3553 nucleotides corresponding to the 3'-terminal region of potato virus S (PVS) has been determined from cloned cDNA. The sequence obtained contains six open reading frames (ORFs) encoding proteins of Mr 10 734, Mr 32 515, Mr 7222, Mr 11 802, Mr 25092 and at least Mr 41052. The sequence of the 33K ORF has been confirmed to be that of the viral coat protein gene. The nucleotide sequence of this ORF was obtained from plasmids which were isolated by colony hybridization with a specific monoclonal antibody to PVS, and the expression of coat protein fusion products was verified by Western blots of bacterial cell lystates. The deduced amino acid sequence of a 70 amino acid portion from the central region of the PVS coat protein was 59~ identical to the analogous region of potato virus X. In addition, the 7K, 12K and 25K ORFs displayed significant sequence homology with the similarly sized ORFs from a number of potexviruses. The partial 41K ORF product was homologous with the C-terminal portion of the viral replicase proteins of potato virus X and white clover mosaic virus.

“…The mutation responsible for the ts phenotype appeared to be a single aa change in the 30K protein (Ohno et al, 1983;Meshi et al, 1987). Taliansky et al (1982) have shown that at the restrictive temperature systemic spread of LS1 could be observed provided the leaves had been preinoculated with PVX. This suggests that the 30K protein function can be provided in trans by a transportation function located on the genome of PVX.…”

Section: F L T S G V P G S G K S T I V Tmentioning

confidence: 99%

The Complete Nucleotide Sequence of Potato Virus X and Its Homologies at the Amino Acid Level with Various Plus-stranded RNA Viruses

Huisman

Linthorst

Bol

et al. 1988

228

132

SUMMARYDouble-stranded cDNA of potato virus X (PVX) genomic RNA has been cloned and sequenced. The sequence [6435 nucleotides excluding the poly(A) tract] revealed five open reading frames (ORFs) which were numbered one to five starting at the 5' terminus of the RNA. They encoded proteins of Mr 165588 (166K), 24622 (25K), 12 324 (12K), 7595 (SK) and 25 080 (coat protein), respectively. ORFs 1 and 2 were inphase coding regions. The ORF 1 product contained domains of homology with the tobacco mosaic virus 126K and 183K products. The ORF 2 and 3 products showed homologies with the barley stripe mosaic virus 58K and 14K proteins, the beet necrotic yellow vein virus 42K and 13K products and the white clover mosaic virus 26K and 13K products, respectively. The significance of these homologies with respect to putative functions of the PVX-encoded proteins are discussed.