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

Abstract

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.

Stem-loop structure in the 5′ region of potato virus X genome required for plus-strand RNA accumulation

“…Cockerham (1955) classi®ed different isolates of PVX into four groups based on phenotype to two endogenous resistance genes in potato. PVX-CP (group 2; Orman et al, 1990), PVX-X3 and PVX-UK3 (group 3;Huisman et al, 1988;Kavanagh et al, 1992), PVX-HB (group 4; Querci et al, 1993), and a Russian isolate that we have designated PVX-R (Skryabin et al, 1988) were compared to our isolate (Hemenway et al, 1988) denoted as PVX-WA. PVX-WA is likely to be a group 3 strain based on amino acid similarities, but has not been tested on the appropriate host plants.…”

“…The capped and polyadenylated viral RNA is composed of an 84 nt 5 H non-translated region (NTR), ®ve open reading frames (ORFs), and a 72 nt 3 H NTR (Huisman et al, 1988;Skryabin et al, 1988). ORF1 encodes the viral replicase protein, which is the only viral protein absolutely required for PVX RNA synthesis.…”

Transgenic Nicotiana debneyii expressing viral coat protein are resistant to potato virus S infection

“…The viral genome consists of one single-stranded, positive sense RNA molecule with an estimated Mr of 2.4 × 106 which contains a T-terminal polyadenylated region. Recent nucleotide sequence data from PVS (MacKenzie et al, 1989) and a related carlavirus, potato virus M (PVM) (Rupasov et al, 1989), have demonstrated that these two viruses have genome organizations similar to that of potato virus X (PVX) (Huisman et al, 1988) and other members of the potexvirus group. The viral genome of PVS contains six open reading frames (ORFs) which encode polypeptides with Mr of 10734, 32515, 7222, 11802, 25092 and more than 41052.…”

Cell-to-cell movement of three genera (+) ss RNA plant viruses

“…On the basis of these properties, Scholthof (2004) classified this type of plant virus transport to the so-called Type II (see Table 1 Final ORF is virus capsid protein, engaged not only in assembling the particles but also in cell-to-cell transport (Huisman et al 1988;Santa Cruz et al 1998).…”