RESUMO
The RNA2 of a German isolate of the bipartite barley mild mosaic bymovirus (BaMMV-ASL1) is 3524 nucleotides long excluding the 3'-terminal poly(A) tail. The isolate was propagated by mechanical inoculation for several years. Electrophoretic comparison of viral nucleic acids during this period revealed that a spontaneous reduction in the length of the RNA2 occurred, resulting in the isolate BaMMV-ASL1a. The deleted RNA2 of BaMMV lacked a fragment that was 630 nucleotides long. The deletion occurred in the 3' half of the single open reading frame (ORF) found in RNA2; this ORF encodes a polyprotein that has a molecular mass of 98 kDa, which is assumed to be processed autocatalytically into proteins of 25 kDa and 73 kDa. A full-length cDNA of the deleted RNA2 was synthesized and cloned under the control of the phage T7 promoter. In vitro transcripts of the BaMMV-ASL1a clone replicated in barley plants after co-inoculation with a wild-type-like isolate of BaMMV. The deletions in RNA2 of BaMMV-ASL1a and those of a number of other isolates that were examined were found to affect a domain of the putative 73 kDa protein that is obviously not essential for replication but may be important for the transmission of BaMMV by its natural vector Polymyxa graminis.
Assuntos
Potyvirus/fisiologia , RNA Mensageiro/genética , RNA Viral/genética , Deleção de Sequência , Replicação Viral/genética , Sequência de Bases , DNA Complementar/genética , DNA Recombinante/genética , Hordeum/virologia , Dados de Sequência Molecular , Fases de Leitura Aberta/genética , Potyvirus/genética , RNA Viral/isolamento & purificaçãoRESUMO
The sequence of 1,787 nucleotides (nts) in the genomic RNA of pelargonium leaf curl virus (PLCV) was determined. It included the entire coat protein (cp) gene (nts 585 to 1,754), 558 nts of the 3' end of the putative RNA polymerase gene, 26 nts of an intercistronic region between the two genes and 33 nts downstream of the stop codon of the cp gene. The cp gene was cloned into the expression vector pET8c and expressed in E. coli. The deduced cp amino acid sequence of PLCV was compared with those of five other tombusviruses. The closer the degree of serological relatedness between two viruses, the more similarity was found in their cp amino acid sequences not only in the protruding domains, but also in their random and shell domains and in the arm regions. Nucleic acid hybridization tests, cp amino acid comparisons and serological tests all suggest the same order of sequence for the relationships in the tombusvirus group.
Assuntos
Capsídeo/genética , Vírus de Plantas/genética , Sequência de Aminoácidos , Sequência de Bases , Capsídeo/química , DNA Viral , Dados de Sequência Molecular , Plantas/microbiologia , Alinhamento de SequênciaRESUMO
A full-length cDNA clone of an aphid non-transmissible isolate of plum pox potyvirus (PPV) was rendered biologically active when placed under the control of the cauliflower mosaic virus 35S RNA promoter and the nopaline synthase polyadenylation signal. The cDNA was constructed so that the exact 5' end of the PPV RNA was present at the transcription initiation site. Inoculation of plasmid DNA onto Nicotiana benthamiana led to systemic infection, whereas local lesions were produced in Chenopodium amaranticolor and C. quinoa, typical of an infection with PPV. Examination of infected plants revealed PPV-specific virus particles as well as viral RNA, the coat protein and the non-structural large nuclear inclusion protein (NIb).
Assuntos
Vírus de Plantas/genética , Plantas/microbiologia , Vírus de RNA/genética , Clonagem Molecular , Microscopia Eletrônica , Vírus de Plantas/patogenicidade , Plantas Tóxicas , Vírus de RNA/patogenicidade , Sequências Reguladoras de Ácido Nucleico/genética , Nicotiana/microbiologia , Transcrição Gênica , Árvores/microbiologia , VírionRESUMO
The complete nucleotide sequence of the RNA of an aphid non-transmissible plum pox virus (PPV-NAT) isolate has been determined from five overlapping cDNA clones. cDNA prepared by primer extension was used to determine the 5' terminus. The assembled RNA is 9741 nucleotides in length, excluding a 3' terminal poly(A) sequence. One large open reading frame starts at nucleotide positions 36 to 38 and is terminated with an UAG codon at positions 9522 to 9524. The putative start codon is located at positions 147 to 149. The encoded polyprotein has a predicted Mr of 353.8K. Comparison of cistrons from tobacco vein mottling virus and tobacco etch virus with those predicted for PPV-NAT indicated a similar genome organization. A highly conserved sequence of 12 nucleotides was found in the 5' non-coding region of these three potyviruses. The potential polyadenylation signal from yeast (UAUGU) was found in the 3' non-coding region of PPV-NAT and several other members of the potyvirus group.
