NUCLEOTIDE-SEQUENCE OF COAT PROTEIN GENE FOR GPV ISOLATE OF BARLEY YELLOW DWARF VIRUS AND CONSTRUCTION OF EXPRESSION PLASMID FOR PLANT

GPV is a Chinese serotype isolate of barley yellow dwarf virus (BYDV) that has no reaction with antiserum of MAV, PAV, SGV, RPV and RMV. The sequence of the coat protein (CP) of GPV isolate of BYDV was identifi ed and its amino acid sequence was deduced. The coding region for the putative GPV CP is 603 bases nucleotides and encodes a Mr 22 218 (22 k u) protein. The same as MAV, PAV and RPV, GPV contained a second ORF w ithin the coat protein coding region. This protein of 17 024 Mr (17 ku ) is thought to correspond to the Virion protein genome linked (Vpg). Sequence comparisons of the CP coding region between the GPV isolate o f BYDV and other isolates of BYDV have been done. The nucleotide and a mino acid sequence homology of GPV has a greater identity to the seque nce of RPV than those of PAV and MAV. The GPV CP sequence shared 83.7% of nucleotide similarity and 77.5% of deduced amino acid similarity, whereas that of the PAV and MAV shared 56.9%, 53.2% and 44.1%, 43.8% r espectively. According to BYDV-GPV CP sequence, two primers were desig ned. The cDNA of CP was produced by RT-PCR. Full-length cDNA of CP was inserted into plasmid to construct expression plasmids named pPPI1, p PPI2 and pPPI5 based on different promoters. The recombinant plasmids were identified by using alpha-P-32-dATP labelled CP probe, alpha-P-32 -ATP labelled GPV RNA probe and sequencing to confirm real GPV CP gene cDNA in plasmids.