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1.
Barley mild mosaic virus is a member of theBymoviruses, a genus of the familyPotyviridae. The virus consists of two types of flexuous rod-shaped particles. Each of them contains one single-stranded polyadenylated RNA in plus orientation of approximately 7.6 kb (RNA1) and 3.6 kb (RNA2). Complementary DNAs of both RNAs have been synthesised and cloned. The nucleotide sequence of RNA2 has been determined. It is 3524 nucleotides in length, excluding the 3 poly(A) tail, and contains one large open reading frame (2679 nts), coding for a polyprotein of approximately 98 kDa. There are indications that a putative proteolytic activity in the N-terminal part can cleave the polyprotein autocatalytically into a 25 kDa protein (putative proteinase) and a 73 kDa polypeptide of unknown function.  相似文献   

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The sequence of the 3 terminal 1722 nucleotides (nts) of RNA1 of the type (Canadian) isolate of wheat spindle streak mosaic bymovirus (WSSMV-C) was determined. The sequence started within a single open reading frame (ORF), which was expected to encode the carboxyl terminus of the nuclear inclusion b protein (NIb) and the capsid protein (CP) of 294 amino acids, followed by a 3 untranslated region (UTR) of 237 nucleotides. The NIb and CP of WSSMV-C share 99 and 100% amino acid sequence identity with the corresponding proteins of WSSMV-French isolate (WSSMV-F), but only 89 and 77% with wheat yellow mosaic virus (WYMV-J), respectively. The 3UTR of RNA1 of WSSMV-C shares 94% nucleotide sequence identity with that of WSSMV-F but only 73% with WYMV-J and WYMV-Chinese isolate (WYMV-Chi). The results support the classification of WSSMV-C and WSSMV-F as strains of the same virus species which is distinct from WYMV.  相似文献   

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The sequence of the 3-terminal 2074 nucleotides (nts), excluding the 3-poly (A) tail, of RNA of a potyvirus isolated from lily (Lilium Asiatic hybrid cv. Enchantment) in Japan, currently tentatively designated as Tulip breaking virus-li (TBV-li), was determined. The sequence started within a single open reading frame (ORF) that encoded the carboxyl terminus of the large nuclear inclusion protein (NIb) and the complete 275-amino-acid coat protein (CP), followed by a 3-untranslated region (3-UTR) of 204 nts. The CP of TBV-li shared 91% amino acid (aa) sequence identity with that of TBV lily strain Dutch isolate (TBV-lily). The nt sequences of their 3-UTR were 94% identical. However both viruses shared only 60–65% sequence identities with TBV tulip strain Niigata isolate in the corresponding regions. The results suggest that TBV-li is closely related to TBV-lily, and that these two TBV lily strains should be classified into a species different from TBV tulip strains. We therefore support a proposal to rename TBV-lily Lily mottle virus (LMoV), and suggest that TBV-li is another strain of LMoV (LMoV-J).  相似文献   

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Eight isolates of Grapevine virus A (GVA), which induced different symptoms in leaves of Nicotiana benthamiana, were recovered from various grapevines. The dsRNA patterns of two isolates, which consistently induced mild vein clearing (referred here as mild isolates of GVA) were similar, but different from those of other isolates of GVA. Analysis based on overall nucleotide (nt) sequence identity in the 3 terminal part of the GVA genome, comprising part of ORF3 (putative movement protein, MP), entire ORF4 (capsid protein, CP), entire ORF5 and part of 3 UTR, revealed that GVA isolates separate into three groups (I, II, III), sharing 91.0–99.8% nt sequence identity within groups and 78.0–89.3% nt sequence identity between groups. Mild isolates of the virus were group III and shared only 78.0–79.6% nt sequence identity with the other isolates. The comparison of predicted amino acid sequences for MP and CP revealed many amino acid alterations, revealing distinct local net charges of these proteins for mild isolates of the virus. Based on both conserved and divergent nt regions in the CP and ORF5, oligonucleotide primers were designed for the simultaneous RT-PCR detection of all GVA isolates and for the specific detection of the most divergent virus variants represented here by mild isolates of the virus.  相似文献   

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In order to characterise and classify an unknown maize-infecting potyvirus isolated from fields in northeast Spain, the entire coat protein gene and the C-terminal twothirds of the large nuclear inclusion protein (NIb) gene were cloned and sequenced. Protein sequencing enabled the cleavage site between the two proteins to be deduced and also revealed that on storage the viral coat protein undergoes a specific degradation in which the N-terminal 39 amino acids are removed. Comparison of the nucleotide sequence of the 3 non-coding region of the viral RNA and the predicted amino acid sequence of the coat protein with the equivalent regions of other members of the potyvirus group revealed that the Spanish virus is closely related to maize dwarf mosaic virus strain A.  相似文献   

8.
To identify possible sites of viral attenuation, the complete nucleotide sequences of two isolates of Zucchini yellow mosaic virus (ZYMV) were determined; a severe isolate Z5-1 and an attenuated isolate from Z5-1 (designated ZYMV-2002). The viral genome of both isolates consisted of 9593 nucleotides in size and contained an open reading frame encoding a single polyprotein of 3080 amino acids. Comparison of the nucleotide sequences for Z5-1 and ZYMV-2002 revealed 14 nucleotide mutations, resulting in seven amino acid substitutions with four in the HC-Pro region, two in the CI region, and one in the NIb region. These results provide a genetic basis for future manipulation of the ZYMV reverse genetics system. The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under the accession numbers AB188115 and AB188116  相似文献   

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A sterile white fungus was isolated from the healthy looking roots of buffalo grass (Stenotaphrum secundatum) grown on cleared bush land in Perth, Western Australia. The fungal strain was pathogenic on 12 plant species screened under the greenhouse conditions. The clamp connections and dolipore septa indicated that the isolate was a Basidiomycete. Mycelial features, growth rate at different temperatures, as well as pathogenicity patterns of this sterile white basidiomycete (SWB) were distinctly different from those of a strain with a similar morphology, ATCC 28344, previously described as a pathogen in Florida and Georgia (USA). All attempts to induce sporulation failed. The isolates were also compared using the nucleotide sequence analysis of the ribosomal DNA array. Approximately 1 kbp of the 5 end of the large subunit ribosomal RNA gene, complete sequences of the small subunit ribosomal RNA gene and the entire ITS region (including ITS1, ITS2 and 5.8S gene) were sequenced for the purpose. The obtained sequences were compared with the homologous regions of other genera of Agaricales available in GenBank. Relatively low sequence similarities between the American and Australian strains, as well as the phylogenetic analysis of the studied regions has suggested that these two fungi belong to different genera. Interesting results were achieved in the case of the large subunit ribosomal DNA since this region has been widely studied for taxonomy of Basidiomycetes. The Australian strain 3034 appeared to be closely related to the genus Campanella and the American SWB was identified as belonging to the genus Marasmius, possibly to M. graminum. Our data suggest that the Australian strain is a novel pathogen, and is different from the American SWB isolates described to date.  相似文献   

10.
Virus interactions between Tomato spotted wilt virus (TSWV) and Potato virus X (PVX) containing the nucleocapsid protein (N) gene sequences were examined to evaluate the capacity of the N gene sequences from TSWV to promote RNA-mediated cross-protection. Plants simultaneously inoculated with TSWV and PVX containing the 3 96bp of the N gene were highly resistant to TSWV infection, whereas no such resistance was observed in plants inoculated with TSWV and PVX containing the 5 96bp. These results suggest that the 3 portion of the N gene has a higher capacity for promoting RNA-mediated cross-protection of TSWV.  相似文献   

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In April 2001, stunted barley plants bearing mosaic symptoms were observed in a field in France (Marne Department, 51). Rod-shaped and flexuous particles were visualized by electron microscopy and positive serological reactions were detected by ELISA with Barley yellow mosaic virus (BaYMV) and Soil-borne cereal mosaic virus (SBCMV) polyclonal antisera. The tubular virus which was soil transmissible to barley cv. Esterel was separated from BaYMV by serial mechanical inoculations to barley cv. Esterel. This furo-like virus, in contrast to a French isolate of SBCMV, could be transmitted to Hordeum vulgare, Avena sativa, Beta vulgaris and Datura stramonium. RT-PCR was used to amplify the 3′-terminal 1500 nucleotides of RNA1 and the almost complete sequence of RNA2. Nucleotide and amino acid sequence analyses revealed that the French virus infecting barley is closely related to a Japanese isolate of Soil-borne wheat mosaic virus (SBWMV-JT) which was originally isolated from barley. This French isolate was named SBWMV-Mar. The 3′ UTRs of both RNAs can be folded into tRNA-like structures which are preceded by a predicted upstream pseudoknot domain with seven and four pseudoknots for RNA1 and RNA2, respectively. The four pseudoknots strongly conserved in RNAs 1 and 2 of SBWMV-Mar show strong similarities to those described earlier in SBWMV RNA2 and were also found in the 3′ UTR of Oat golden stripe virus RNAs 1 and 2 and Chinese wheat mosaic virus RNA2. Sequence analyses revealed that the RNAs 2 of SBWMV-Mar and -JT are likely to be the product of a recombination event between the 3′ UTRs of the RNAs 2 of SBWMV and SBCMV. This is the first report of the occurrence of an isolate closely related to SBWMV-JT outside of Japan.  相似文献   

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The coding sequences in RNA2 for the coat proteins (CP) of strawberry latent ringspot virus (SLRSV) were modified and amplified using polymerase chain amplification reactions (PCR) to facilitate their expression inAgrobacterium tumefaciens-transformedNicotiana tabacum Xanthi-nc. The coding sequences for the smaller capsid protein (S, 29kDa) and that for the theoretical precursor of L and S (P, 73kDa) had ATG initiation codon sequences added at the 5-proximal Ser/Gly (S/G) cleavage site in the unmodified sequence. The sequence coding for the larger of the two proteins of mature SLRSV capsids (L, 44kDa) had an ATG codon added at its 5 S/G site and a TAG stop codon sequence added at the 3-proximal S/G site. The P, L and S proteins were expressedin planta to a maximum concentration of 0.01 % of total extractable proteins but did not assemble into virus-like particles. When challenged by mechanical inoculation with virus particles or viral RNA, and compared with control plants, tobacco plants (primary transgenic clones or S1 and S2, kanamycin-resistant seedlings) expressing the virus capsid subunits separately, or their precursor, decreased the accumulation of SLRSV particles in inoculated leaves and fewer plants became invaded systemically. In experiments in which the roots of seedlings were exposed to SLRSV-carrying vector nematodes (Xiphinema diversicaudatum), SLRSV was detected in the roots of non-transformed control tobacco plants (6/20) and in transgenic tobacco expressing the L protein (7/40), but not in any of 25 tobacco plants expressing the S protein or in 35 expressing the P protein. This is the second example of CP-mediated resistance to virus inoculation by nematode vectors.  相似文献   

13.
Cowpea mild mottle virus (CMMV) has physicochemical properties typical of carlaviruses, but has remained unclassified due to a number of unusual properties, including no serological cross-reaction with 18 carlaviruses; production of brush-like inclusion bodiesin vivo; and the ability to be transmitted by whiteflies (Bermisia tabaci). In this paper we report the use of a carlavirus specific PCR primer to identify CMMV as a member of the carlavirus group. This is confirmed by nucleotide sequence (958 nucleotides) from the 3 terminal region of CMMV RNA which contains a partial open reading frame (ORF) having high similarity with the coat proteins of other carlaviruses. The sequence also contains an 11.7K ORF at the 3 terminus, containing a zinc-finger motif which is unique to carlaviruses.  相似文献   

14.
A technique based on the use of specific primers for polymerase chain reaction (PCR) was developed for the identification of the stem and bulb nematode belonging to the Ditylenchus dipsaci species complex. The internal transcribed spacer region ITS1 and ITS2, the gene 5.8 S and part of genes 18 S and 26 S of twenty populations of the D. dipsaci species complex belonging to both D. dipsaci sensu stricto and Ditylenchus sp. B (corresponding to populations of giant individuals associated to Vicia faba) and three congeneric species were amplified with two universal ribosomal primers. PCR-amplified DNA samples were digested with five restriction enzymes in order to reveal some polymorphism allowing the identification of D. dipsaci populations associated with Fabaceae seeds. The polymorphism among species was confirmed by the sequencing of the PCR products. A primer (DdpS2) was designed in a region conserved in all populations of both D. dipsaci sensu stricto and D. sp. B studied in the present work. The other Anguinidae species (except a few species from Central Asia associated to Astereaceae and D. sp. G associated to Plantago maritima) differ in two to four nucleotides at the 3′ extremity of this region. This sequence portion coincides with a TspEI restriction site. In combination with a primer located in the ribosomal region, this first primer is a good candidate for identification by PCR of populations of the D. dipsaci species complex found in Fabaceae seeds. A second primer (DdpS1) was designed in a similar way and was specific to D. dipsaci sensu stricto. The utility of these two sets of primers is discussed against the background of quarantine regulation.  相似文献   

15.
Brown rot and twig canker of fruit trees are caused by Monilinia laxa, M. fructigena and M. fructicola. The Internal Transcribed Spacer (ITS) between the 18S and the 28S rRNA genes of four M. laxa and four M. fructigena isolates collected in France was amplified by Polymerase Chain Reaction (PCR) using universal primers and sequenced. Multiple alignment of the ITS sequences and comparison with published sequences revealed very little intraspecific variation and a low interspecific polymorphism clustered in two regions. Species-specific PCR primers were designed to amplify a 356bp fragment for each of the three species. The specificity of the three primer pairs was successfully tested with a collection of 17 M. laxa, 18 M. fructigena and 6 M. fructicola isolates collected from different hosts and different countries, unequivocally confirming the identification of each isolate based on morphological and cultural traits. Using stringent PCR conditions, no cross-reaction was observed with any of the isolates tested. The specificity of the PCR assays was also successfully confirmed with DNA extracted from different fungal species, either phylogenetically close to the genus Monilinia or commonly found on diseased fruits. Using this new reliable technique, doubtful isolates can be directly identified in a single PCR run. Moreover, detection and identification of the Monilinia species were successfully achieved directly on diseased fruits. This simple and rapid method can be particularly useful to detect M. fructicola which is a listed quarantine fungus in all European countries.  相似文献   

16.
Two primer sets were designed based on the sequence of polymorphic bands that were derived from repetitive sequence-based polymerase chain reaction (rep-PCR) fingerprinting and specifically detected in Ralstonia solanacearum race 4 strains (ginger, mioga, and curcuma isolates). One primer set (AKIF-AKIR) amplified a single band (165bp) from genomic DNA obtained from all mioga and curcuma and some ginger isolates; another set (21F-21R) amplified one band (125bp) from the other ginger isolates. These primer sets did not amplify the bands from genomic DNA of other R. solanacearum strains or of other related bacteria. PCR detection limit for the pathogen was 2 × 102cfu.The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under accession numbers AB118756 and AB118757  相似文献   

17.
The 2326 nucleotides of the 3′-terminal region of Carnation vein mottle virus (CVMV) RNA, which included part of the nuclear inclusion b gene, the complete coat protein (CP) gene and the entire 3′-noncoding region (3′-NCR) were determined. The region encoding the CP gene is 843 nucleotides long and the deduced protein consists of 280 amino acids. A search of the EMBL and PIR databases showed that the amino acid sequence of CVMV CP most resembled that of Plum pox virus with a similarity of 67.9%. The 3′-NCR of CVMV RNA is 541 nucleotides long, second longest in the genus Potyvirus. These results indicate that CVMV is closely related to Plum pox virus but is a distinct species in the genus Potyvirus. Received 8 October 1999/ Accepted in revised form 9 January 2000  相似文献   

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Pepper mottle virus, genus Potyvirus, was first identified in Japan based on particle morphology, host range, aphid transmission, and molecular classification using the nucleotide sequence of the coat protein gene and 3-untranslated region.  相似文献   

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Rose yellow mosaic virus, which belongs to the Roymovirus genus in the Potyviridae family, was isolated here in Japan from a rose cultivar, Irish Mist. The full-length genomic sequence was similar to a strain in Minnesota, United States, which was the first ever isolated, with 85% nucleotide and 94% amino acid sequence similarities. Unlike the Minnesota strain, which lacks 220 nt including the 6K1 protein region, the Japanese isolate contains this coding region, which is commonly found in those of the Potyviridae.

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