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.

No abstract

The nucleotide sequence of the genomic RNA of potato leafroll virus was determined and its genetic organization deduced. The RNA is 5882 nucleotides long and contains 6 open reading frames (ORFs) encoding proteins of 70, 70, 56, 28, 23 and 17 kDa. The putative genes for the coat protein (23 kDa) and the RNA-dependent RNA polymerase (70 kDa) were identified by interviral amino acid sequence homologies. For expression of the different ORFs, translational frameshift and readthrough events are proposed.cDNA cloning; Nucleotide sequence; Amino acid sequence homology; RNA virus, plant positive-strand; (Potato leafroll virus)

No abstract

SUMMARYThe nucleotide sequence of the genomic RNA of narcissus mosaic virus (N MV) was deduced from a set of cDNA clones and by direct sequencing of RNA. The genome, with a length of 6955 nucleotides [excluding the 3'poly(A) tail], contains six open reading frames (ORFs) with the capacity to code for polypeptides of more than 1 OK, with Mr values of 186284, 25845, 13998, 11059, 26097 and 10519. The first five of these putative proteins show considerable homology to similar proteins encoded by the RNAs of potato virus X (PVX, 6435 nucleotides) and white clover mosaic virus (WCIMV, 5845 nucleotides). The sixth ORF is completely overlapped by the Mr 26 097 coat protein cistron and has some homology with a similar ORF in WC1MV RNA. The difference in length of the RNAs of NMV, PVX and WCIMV is due to a nonhomologous domain of variable length in the central region of the 5'-proximal ORF of the three viruses.