Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
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| cleavage of potato virus y polyprotein in escherichia coli depending on the proteolytic activity of viral protease. | we have cloned a 5-kb cdna corresponding to the 3'-half of genomic rna of potato virus y (pvy), the type member of plant potyvirus. based on its nucleotide sequence, the cdna was presumed to encode pvy protease responsible for the self-processing of polyprotein precursor expressed from pvy genome. to test its proteolytic activity, the cdna was modified so as to express the protease-polymerase-coat protein (cp) portion of pvy polyprotein in escherichia coli. by western blotting analysis of the ce ... | 1993 | 7763774 |
| mutational analysis of the amino acid residues essential for the cis and trans cleavage activity of the potato virus y 50-kda protease. | to examine the proteolytic activities of various truncated derivatives of the potato virus y (pvy) 50-kda protease, the derivatives were expressed in escherichia coli in polyprotein forms fused with coat protein (cp). for the intermolecular cleavage reaction, the truncated proteases were expressed together with the substrate protein containing the polymerase-cp junction. the activity was evaluated by the amount of the mature cp released from the precursor by the intra- and intermolecular cleavag ... | 1993 | 7764224 |
| the 5' untranslated region of pvy rna, even located in an internal position, enables initiation of translation. | potato virus y (pvy) is the type member of the potyvirus group. potyviruses, like picorna-, como-, and nepoviruses, belong to the picornavirus-like supergroup. all these viral rnas have a vpg at their 5' end, and for four picornaviruses and one comovirus internal initiation of translation has been reported. to know if such a translational mechanism holds true for potyviral rnas, the 5' nontranslated region (ntr) of pvy rna was placed in an internal position, either by adding 91 bases upstream of ... | 1993 | 8122396 |
| characterization of antigenic epitopes of potato virus y. | immunochemical analysis of overlapping synthetic hexapeptides covering the entire length of the coat protein of potato virus y (pvy) revealed immunodominant regions both at the n-terminal and at the c-terminal end of the coat protein. immunization of rabbits with synthetic peptides representing n- and c-terminal regions of the coat protein resulted in production of antibodies that reacted with pvy. antigenicity of pvy peptides was found to correlate with predicted beta turns, with hydrophilicity ... | 1993 | 7680576 |
| induction of a highly specific antiviral state in transgenic plants: implications for regulation of gene expression and virus resistance. | transgenic tobacco plants expressing either a full-length form of the tobacco etch virus (tev) coat protein or a form truncated at the n terminus of the tev coat protein were initially susceptible to tev infection, and typical systemic symptoms developed. however, 3 to 5 weeks after a tev infection was established, transgenic plants "recovered" from the tev infection, and new stem and leaf tissue emerged symptom and virus free. a tev-resistant state was induced in the recovered tissue. the resis ... | 1993 | 12271055 |
| improvement in the sensitivity of pvyn detection by increasing the cdna probe size. | cloned cdna to a north american isolate of tobacco veinal necrotic strain of potato virus y (pvyn) rna was used for the detection of pvyn in diseased samples. digoxigenin-labelled cdna probes were prepared from approximately 0.56 kb, approximately 1.2 kb, approximately 2.5 kb, and approximately 3.25 kb overlapping clones representing the 3'-terminus of the pvyn genome. it was shown that the probe sizes, as determined by alkaline gel-electrophoresis, generally corresponded to the size of the temp ... | 1994 | 7714042 |
| digoxigenin-labelled molecular probe for the simultaneous detection of three potato pathogens: potato spindle tuber viroid (pstvd), potato virus y (pvy), and potato leafroll virus (plrv). | a molecular probe, p3pot, was constructed of pstvd, pvy, plrv cdna fragments introduced into puc18 vector. sequencing of the inserts revealed that cloned fragments covered conservative parts of pathogenic genomes. dot-blot hybridization of digoxigenin-labelled construct to crude extracts from plants infected with different potato viruses proved high sensitivity and specificity of the p3pot probe. this makes p3pot probe an useful tool for the routine testing, and selection of virus-free potatoes. | 1994 | 7732766 |
| replicase-mediated resistance to potato virus y in transgenic tobacco plants. | nicotiana tabacum 'turkish samsun nn' plants were transformed with nuclear inclusion b (nib) gene sequences of potato virus y, o strain (pvyo). the full-length construct included an additional in-frame initiation codon contiguous to the putative n-terminal amino acid codon and a stop codon replacing the c-terminal amino acid codon. of 13 independently transformed lines, four yielded 37 (out of 100) plants in the r1 generation that were resistant to pvyo infection. progeny of 13 out of 15 of r1 p ... | 1994 | 8167367 |
| a pcr-microplate hybridization method for plant virus detection. | a sensitive nonradioactive method for detection of plant viruses was evaluated. a cdna fragment from the coat protein coding region of the potato virus y (pvy) rna genome amplified by reverse transcription (rt) followed by polymerase chain reaction (pcr), was directly adsorbed onto polystyrene microplate wells after heat denaturation. the adsorbed cdna was hybridized with a digoxigenin (dig)-labelled cdna probe without a prehybridization step. the probe was also prepared by pcr using the same pa ... | 1994 | 8188816 |
| mutations in the helper component protease gene of zucchini yellow mosaic virus affect its ability to mediate aphid transmissibility. | the nucleotide sequence of the helper component protease (hc-pro) genes of three zucchini yellow mosaic virus (zymv) strains has been compared with that of a helper-deficient strain of zymv-hc. the comparisons revealed three unique deduced amino acid differences. two of these mutations were located in regions which are conserved in other potyviruses. the role of these mutations in aphid transmissibility was examined by exchanging dna fragments of part of the deficient hc-pro gene with the respec ... | 1994 | 8207404 |
| small-scale field tests with transgenic potato, cv. bintje, to test resistance to primary and secondary infections with potato virus y. | the coat protein (cp) gene of the potato virus y (pvy) strain n605 has been cloned into a plant binary expression vector and introduced into the potato variety bintje. the transformed lines, bt6, that contained two copies of the cp gene showed complete resistance to the homologous strain pvy-n605 and a good resistance to the related strain pvy-o803 in the greenhouse. the good resistance of bt6 to primary and secondary infections by pvy was confirmed in two successive field tests where the virus ... | 1994 | 7919216 |
| characterization and strain identification of a potato virus y isolate non-reactive with monoclonal antibodies specific to the ordinary and necrotic strains. | an isolate of potato virus y, named pvy-36, reacted with polyclonal antibody against pvy-o (an ordinary strain), but not with any of eight monoclonal antibodies (mabs) specific to pvy-o or with two mabs specific to pvy-t (a necrotic strain). from its host range and symptomatology, pvy-36 belongs to the pvyo group. the nucleotide sequence of the coat protein (cp) coding region of the pvy-36 genome was determined and the amino acid sequence was predicted. based on the cp amino acid sequence, pvy-3 ... | 1994 | 7928283 |
| molecular cloning and sequencing of the capsid and the nuclear inclusion protein genes of a north american pvyn isolate. | the sequence of the 3'-terminal 3258 nucleotides of a tobacco veinal necrosis strain of a potato virus y (pvyn) isolate from north america was determined. the sequence revealed an open reading frame of 2931 nucleotides, of which the start codon was not identified. the nontranslated region contains 327 nucleotides upstream of a poly(a) tract. the open reading frame encodes a large polyprotein containing 976 amino acids. the data indicate that the coat protein (cp) and the nuclear inclusion protei ... | 1994 | 7954114 |
| [the effect of the 5'-leader of potato x-virus on expression of the gene for the potato y virus membrane protein in transgenic solanum tuberosum]. | the 5'-leader of potato virus x (pvx) genomic rna was successfully used to generate potato plants expressing the coat protein of the potato virus yn (russian isolate) (pvy cp). two expression cassettes were constructed that carried the pvy cp coding sequence along with the pvy 3'untranslated region under the control of the camv 35s promoter and poly(a) signal. the cassettes contained different sequences between the 35s promoter and the cp artificial aug initiating codon of the coat protein: eith ... | 1994 | 7990802 |
| transgenic plant virus resistance mediated by untranslatable sense rnas: expression, regulation, and fate of nonessential rnas. | haploid leaf tissue of tobacco cultivars k326 and k149 was transformed with several transgenes containing cdna of the potato virus y (pvy) coat protein (cp) open reading frame (orf). the various transgenes containing the pvy cp orf sequence produced (1) the expected mrna and cp product, (2) an mrna rendered untranslatable by introduction of a stop codon immediately after the initiation codon, or (3) an antisense rna that was untranslatable as a result of the incorrect orientation of the pvy cp o ... | 1994 | 7994177 |
| principles and background for the construction of transgenic plants displaying multiple virus resistance. | we investigated the possibility of reconstructing the 2'-5' oligoadenylate (2-5a) pathway into the plant kingdom to achieve multiple virus resistance. differently phosphorylated 2-5a trimers and tetramers inhibited tmv rna translation in cell-free systems. in wheat germ extracts the most potent inhibitors were nonphosphorylated forms of 2-5a. triphosphorylated forms of 2-5a were deposphorylated and hydrolysed in plant extracts. since we could not detect homologous dna to mammalian 2-5a synthetas ... | 1994 | 8032271 |
| distinct functions of capsid protein in assembly and movement of tobacco etch potyvirus in plants. | tobacco etch potyvirus engineered to express the reporter protein beta-glucuronidase (tev-gus) was used for direct observation and quantitation of virus translocation in plants. four tev-gus mutants were generated containing capsid proteins (cps) with single amino acid substitutions (r154d and d198r), a double substitution (dr), or a deletion of part of the n-terminal domain (delta n). each modified virus replicated as well as the parental virus in protoplasts, but was defective in cell-to-cell ... | 1994 | 7511101 |
| resistance to potato virus y in somatic hybrids between solanum etuberosum and s. tuberosum x s. berthaultii hybrid. | somatic hybrids between a potato virus y (pvy) resistant solanum etuberosum clone and a susceptible diploid potato clone derived from a cross between s. tuberosum gp. tuberosum haploid us-w 730 and s. berthaultii were evaluated for resistance to pvy. all but one of the tested somatic hybrids were significantly more resistant than cultivars 'atlantic' and 'katahdin'. however, none was as resistant as the s. etuberosum parent. one hexaploid somatic hybrid, possibly the product of a triple-cell fus ... | 1994 | 24178025 |
| resistance against multiple plant viruses in plants mediated by a double stranded-rna specific ribonuclease. | many plant viruses have single-stranded rnas as their genomes. during the course of replication, genomic rnas and their complementary template rnas are likely to form double-stranded (ds) rna at least transiently. to attack replication intermediates of many plant rna viruses specifically, we introduced a yeast-derived ds-rna specific rnase gene called pac 1 into plants. the transformed plants showed a decrease in lesion numbers when they were challenged with tomato mosaic virus, and a delay in t ... | 1995 | 7556661 |
| transmission by aphids of a naturally non-transmissible plum pox virus isolate with the aid of potato virus y helper component. | two spanish plum pox virus (ppv) isolates, 5.15 and 3.3, were used in transmission experiments involving the aphid vector myzus persicae, with woody and herbaceous host plants. these isolates differ in the size of their coat protein (cp) and sequence analysis revealed that isolate 3.3 has a 15 amino acid deletion near the n terminus of the cp, affecting the same positions as in a previously reported non-aphid-transmissible ppv isolate from germany. aphid transmission experiments showed that isol ... | 1995 | 7561767 |
| a simplified procedure for the subtractive cdna cloning of photoassimilate-responding genes: isolation of cdnas encoding a new class of pathogenesis-related proteins. | transgenic tobacco plants (ppa-1) constitutively expressing escherichia coli pyrophosphatase behind the 35s camv promoter accumulate high levels of soluble sugars in their leaves [27]. these plants were considered a tool to study adaptation of leaves to photoassimilate accumulation at the molecular level. by differential hybridization of a subtractive library enriched for transcripts present in the transgenic plants 12 different cdnas were isolated. by sequence analysis four cdnas could be ident ... | 1995 | 8555446 |
| digoxigenin-labelled cdna probes for the detection of potato virus y in dormant potato tubers. | an isolate (y139) of the potato virus y strain pvyo, common in the potato-growing regions of eastern canada, was cloned and segments of about 1800 bases from the 3'-end of the pvy-genome were sequenced. these clones were used to prepare molecular detection probes by labelling with digoxigenin. five methods reported to yield nucleic acid preparations from tuber tissue were compared. two of the methods failed to yield nucleic acids from tubers suitable for use in dot-blot hybridization. the other ... | 1995 | 7769026 |
| 5' proximal potyviral sequences mediate potato virus x/potyviral synergistic disease in transgenic tobacco. | the interaction of potato virus x (pvx) and potato virus y (pvy) in tobacco causes a synergistic disease characterized by a dramatic increase in symptom severity, a change in the regulation of pvx rna replication, and an increase in accumulation of pvx. in this study we demonstrate that pvx also interacts synergistically with three other members of the potyvirus group of plant viruses, tobacco vein mottling virus (tvmv), tobacco etch virus (tev), and pepper mottle virus. these synergisms resembl ... | 1995 | 7831814 |
| reason for non-aphid transmissibility in a strain of kalanchoë mosaic potyvirus. | kalanchoë mosaic potyvirus (kmv) is transmitted by aphids in a nonpersistent manner. after multiple mechanical inoculations, a non-aphid-transmissible (nat) variant appeared. addition of purified helper component (hc) from potato virus y-infected plants did not restore the aphid transmissibility of purified kmv-nat. comparison of the nucleotide sequence in the n-terminal half of the coat protein gene of kmv-nat with that of an aphid-transmissible (at) kmv strain revealed a single nucleotide diff ... | 1995 | 8808336 |
| sequence polymorphism in the 5'ntr and in the p1 coding region of potato virus y genomic rna. | potato virus y (pvy) the type member of the genus potyvirus, occurs world-wide as isolates which differ in host range and the type of symptoms caused. the sequences of a 5' segment of viral rna overlapping the 5' non-translated region (5'ntr) alone (ten isolates) or the 5'ntr and the adjacent p1 coding region (eight isolates) were established. these data were used to quantify the polymorphism in the 5'-terminal part of the pvy genome. nucleotide sequence identity between isolates ranged from 66- ... | 1995 | 9049340 |
| three-dimensional model of the potyviral genome-linked protein. | the full sequence of the genome-linked viral protein (vpg) cistron located in the central part of potato virus y (common strain) genome has been identified. the vpg gene codes for a protein of 188 amino acids, with significant homology to other known potyviral vpg polypeptides. a three-dimensional model structure of vpg is proposed on the basis of similarity of hydrophobic-hydrophilic residue distribution to the sequence of malate dehydrogenase of known crystal structure. the 5' end of the viral ... | 1996 | 8901548 |
| virus-induced cell death in plants expressing the mammalian 2',5' oligoadenylate system. | the major components of the 2-5a system, responsible for the mammalian interferon-induced antiviral response, are the 2',5' oligoadenylate synthetase (2-5aase) and 2',5' oligoadenylate (2-5a) dependent ribonuclease (rnase l). transgenic tobacco plants expressing these two enzyme activities were produced by crossing the transgenic plants expressing rnase l with those expressing 2-5aase. the double transgenic plants showed complete resistance against cucumber mosaic virus (cmv), infection with nec ... | 1996 | 9634822 |
| genetic engineering of potato for broad-spectrum protection against virus infection. | transgenic potato plants expressing mutant alleles of plrv orf4, the gene for the movement protein pr17 of this luteovirus, were generated for broad-range protection against virus infection. when tested for protection against infection by plrv, all transgenic lines showed a significant reduction of virus antigen. potato lines accumulating n- or c-terminally extended plrv pr17 mutant proteins were resistant to infection by the unrelated potato viruses pvy and pvx. transgenic lines that did not ex ... | 1996 | 9634829 |
| cell-free cloning and biolistic inoculation of an infectious cdna of potato virus y. | potato virus y (pvy) full-length cdna has been found to be refractory to cloning in escherichia coli cells. a full-length 9.7 kb pvy cdna was obtained by reverse transcription polymerase chain reaction (rt-pcr) from the rna of pvy (tuber necrotic strain, pvyntn). double-stranded dna fragments were used as primers (ds megaprimers), to include signals for transcription in vivo (a cauliflower mosaic virus 35s rna promoter and a nopaline synthase terminator) in the final pcr product. biolistic bomba ... | 1996 | 8601790 |
| loss of potyvirus transmissibility and helper-component activity correlate with non-retention of virions in aphid stylets. | the hypothesis that loss of aphid transmissibility of potyvirus mutants is due to non-retention of virions in the mouthparts was tested by feeding aphids through membranes on purified virions of aphid transmissible (at or hat) and non-aphid-transmissible (nat) tobacco vein mottling virus (tvmv) or tobacco etch virus (tev), in the presence of functional [potato virus y (pvy) hc or tvmv hc] or non-functional (pvc hc) helper component (hc). tvmv virions were detected, by electron microscopic examin ... | 1996 | 8609482 |
| nucleic acid-binding properties of a bacterially expressed potato virus y helper component-proteinase. | the potyvirus helper component-proteinase (hc-pro) is a multifunctional protein previously reported to have affinity for polyribonucleotides. to investigate further the ability of hc-pro to bind nucleic acids, the potato virus y (pvy) lye84 isolate hc-pro gene was amplified, cloned in an escherichia coli expression vector and sequenced. hc-pro was expressed as a fusion with the maltose-binding protein and purified by affinity chromatography. electrophoretic mobility-shift assays demonstrated tha ... | 1996 | 8609483 |
| switches in the mode of transmission select for or against a poorly aphid-transmissible strain of potato virus y with reduced helper component and virus accumulation. | a poorly aphid-transmissible potato virus y (pvy-pat) variant emerged after several cycles of mechanical transmission of an initially aphid-transmissible (at) isolate. sequence analysis of the n-terminal region of the helper component-proteinase (hc-pro) gene revealed a lys to glu change at a position previously found to abolish the hc-pro aphid transmission activity in several potyviruses. two cycles of aphid transmission allowed the virus population to evolve towards an at form (pvy-atnew) whe ... | 1996 | 8757973 |
| frequent occurrence of recombinant potyvirus isolates. | we have performed a systematic search for recombination in the region encoding coat protein and the 3' non-translated region in natural isolates of potyviruses, the largest group of plant rna viruses. the presence of recombination, and the localization of the cross-over points, were confirmed statistically, by three different methods. recombination was detected or suspected in 18 out of 109 potyvirus isolates tested, belonging to four out of eight virus species, and was most prevalent in potato ... | 1996 | 8760448 |
| the complete nucleotide sequence of yam mosaic virus (ivory coast isolate) genomic rna. | the complete nucleotidic sequence of the yam mosaic virus (ymv) rna was determined following the cloning of partial segments of the genome by reverse transcription and polymerase chain reactions (rt-pcr) using degenerate and/or specific oligonucleotide primers. ymv genomic rna is 9,608 nucleotides in length and contains one open reading frame (orf) encoding a polyprotein of 3,103 amino acids (aa) with a calculated mr of 350,915. the 5' leader sequence of ymv rna preceding the orf is 134 nucleoti ... | 1996 | 8774686 |
| factors affecting detection of pvy in dormant tubers by reverse transcription polymerase chain reaction and nucleic acid spot hybridization. | a reverse transcription polymerase chain reaction (rt-pcr) protocol was developed using two 20-mer primers located in nuclear inclusion genes nia and nib of potato virus y (pvy). a 1017 bp pcr-product was detected in dormant potato tubers, infected with pvy(o), but not in tubers from healthy plants. the pcr product was specific to pvy, as determined by southern blot detection by hybridization with a pvy(o)-specific probe. as little as 1 pg of purified pvy(o)-rna can be detected after rt-pcr ampl ... | 1996 | 8795005 |
| a strain-type clustering of potato virus y based on the genetic distance between isolates calculated by rflp analysis of the amplified coat protein gene. | potato virus y (pvy) isolates have been classified into genetic strains by a host-independent criterion using a molecular typing method. the method used extracts from infected tissue, and included immunocapture-rt-pcr-rflp analysis using 5 different restriction endonucleases (dde i, eco rv, hinf i, rsa i and taq i). genetic distances between the different pvy "restrictotypes" were calculated and used to define the pvy genetic strains. three main clusters were found: pvyo, pvyn, and non-potato pv ... | 1996 | 9526547 |
| systemic acquired resistance mediated by the ectopic expression of invertase: possible hexose sensing in the secretory pathway. | systemic acquired resistance (sar) has been reported to be associated with lesion-mimic mutants. tobacco plants expressing vacuolar and apoplastic yeast-derived invertase (vaclnv and cwlnv, respectively) develop spontaneous necrotic lesions similar to hypersensitive responses caused by avirulent pathogens. therefore, sar and metabolic alterations leading to the activation of defense-related responses were studied in these plants. defense-related gene transcripts, callose content, peroxidase acti ... | 1996 | 12239401 |
| both common and specific genetic factors are involved in polygenic resistance of pepper to several potyviruses. | absolute resistance to potato virus y pathotype 0 (pvy 0), potyvirus e and chili veinal mottle virus (cvmv) and a partial resistance to potato virus y pathotype 1,2 (pvy 1,2) were found in an indian pepper line, 'perennial'. in the doubled haploid (dh) progeny from the f1 of a cross 'perennial' by 'yolo wonder', resistance to cvmv was confered by two independent genes, one with a clear dominant effect. resistance to pvy and potyvirus e was quantitatively expressed and controlled by several reces ... | 1996 | 24166111 |
| sequencing and characterization of the coat protein and 3' non-coding region of a new sweet potato potyvirus. | a cdna library was constructed from viral genomic rna purified from sweet potato plants affected by "sweet potato chlorotic dwarf disease" in an attempt to clarify the etiology of this viral complex in argentina. by sequence analysis, some of the obtained clones were found to belong to sweet potato feathery mottle potyvirus (spfmv), to a closterovirus and to a new potyvirus. a cdna clone of 1,103 bp representing the coat protein cistron and 3' non-coding region of the newly identified potyvirus ... | 1997 | 9672624 |
| tobacco veinal necrosis determinants are unlikely to be located within the 5' and 3' terminal sequences of the potato virus y genome. | three potato virus y isolates, representatives of distinct pvy groups, identified in potato fields in northern poland were submitted to biological and molecular analysis. phenotypically, two isolates, pvyn-ny and pvyn-wi, belong to the necrotic strain and the third one (pvyo-lw) to the common strain. pvyn-wi, however, did not react with monoclonal antibodies directed against the necrotic strain isolates which recognise pvyn-ny. to characterise the isolates, coat protein genes were sequenced and ... | 1997 | 9170503 |
| movement protein-derived resistance to triple gene block-containing plant viruses. | two mutant potato virus x (pvx) movement protein (mp) genes (m 12k-sal and m 12k-kpn) were obtained by inserting specific linkers at the boundary between the n-terminal hydrophobic and putative transmembrane segment, and the central invariant hydrophilic region of the respective 12 kda, 12k, triple gene block (tgb) protein. several transgenic potato lines which expressed m 12k-sal or m 12k-kpn to different degrees were resistant to infection by pvx, potato aucuba mosaic potexvirus and the carlav ... | 1997 | 9191914 |
| analysis of the sequence diversity of the p1, hc, p3, nib and cp genomic regions of several yam mosaic potyvirus isolates: implications for the intraspecies molecular diversity of potyviruses. | partial sequences from serologically characterized yam mosaic potyvirus (ymv) isolates were determined in conserved (helper-component proteinase, hc; nuclear inclusion b, nib) and variable (first protein, p1; third protein, p3; and coat protein, cp) regions of the potyviral genome in order to investigate the intraspecies molecular diversity of ymv. multiple sequence alignments and pairwise comparisons were used to quantify the sequence polymorphism in these regions. two levels of diversity were ... | 1997 | 9191916 |
| optimization of purification procedure for potato virus y strain nn. | potato virus y strain nn (pvynn) was purified from mechanically infected plants nicotiana tabaccum cv. samsun by extraction of the plants with various buffers, clarification of the suspensions with chloroform or triton x-100, high speed centrifugation of the virus through sucrose cushion and resuspension of the sedimented virus is different buffers. the two optimal combinations of different procedures tested were either (1) extraction of the plants with the buffer containing 0.3% ascorbic, 0.3% ... | 1997 | 9199715 |
| amplification and cloning of a long rna virus genome using immunocapture-long rt-pcr. | a rapid and easy method was developed in order to amplify long fragments of the genome of potato virus y (pvy), a virus possessing a 10-kb genomic rna. the method of immunocapture-rt-pcr was adapted, by using thermostable dna polymerases with proofreading activity and the proper buffers and cycles, to amplify almost the whole genome of pvy in two fragments (5.6 and 4.3 kb) without purifying virions nor viral rna. both fragments were cloned subsequently and their ends sequenced. the method is app ... | 1997 | 9220402 |
| transgenic accumulation of two plant virus coat proteins on a single self-processing polypeptide. | an expression cassette based on the highly specific tobacco etch potyvirus (tev) nuclear inclusion (nia) proteinase has been developed to produce multiple proteins through the translation of a single self-processing polypeptide. gene constructs encoding tev nia, the tobacco mosaic tobamovirus (tmv) coat protein (cp) and the soybean mosaic potyvirus (smv) cp were used to develop transgenic tobacco plants. proper processing of the multifunctional polypeptide was demonstrated, leading to accumulati ... | 1997 | 9225054 |
| molecular characterization of coat protein genes of serologically distinct isolates of potato virus y necrotic strain. | the cost protein (cp) genes of two potato virus y necrotic isolates (n27 and a mutant strain n27-92), which differed in their reactivity to a monoclonal antibody (mab), were characterized. both isolates could be detected by mab 4e7, but mab vn295.5 selectively reacted to n27 and not to n27-92. the cp genes of both isolates coded for 267 amino acids with approximately 99.0% identity at both the nucleotide and the amino acid levels. nucleotide sequence comparison indicated five substitutions in n2 ... | 1997 | 9246744 |
| induction of antibodies to plant viral proteins by dna-based immunization. | dna-based immunization is a promising new technique for generating antibodies in laboratory animals for diagnostic purposes in biological science. the main advantages are the elimination of time and labor and the technically demanding steps of antigen purification. the dna sequence of the protein of interest, cloned in a suitable in vivo expression vector that is administered intramuscularly or intradermally, is sufficient to induce an immune response in animals. we report the induction of antib ... | 1997 | 9255730 |
| synthesis of full-length potyvirus cdna copies suitable for the analysis of genome polymorphism. | new methods facilitating the synthesis and amplification of full-length cdna copies of single-stranded viral rna genomes have been developed. a method is described for the efficient purification of potyviral rna and total rna from infected plants and it is shown that they can serve as templates for the efficient synthesis of a full-length, 10 kb long, genomic cdna. two different reverse transcriptases were used (amv-rt and mmlv-rt); only the first reverse transcriptase produced a good quality, f ... | 1997 | 9300384 |
| infectious in vivo and in vitro transcripts from a full-length cdna clone of pvy-n605, a swiss necrotic isolate of potato virus y. | a full-length cdna clone of the potato virus y (pvy) genome was obtained after cloning difficulties in escherichia coli were overcome. these difficulties were mainly due to the expression of the ci gene from upstream prokaryotic promoter-like elements within the pvy genome. to overcome this problem, pvy cdna was maintained in two subclones which were ligated before infection. a plasmid in which these two fragments were contained could be propagated in some e. coli strains but was unstable and yi ... | 1997 | 9400962 |
| expression of a luteoviral movement protein in transgenic plants leads to carbohydrate accumulation and reduced photosynthetic capacity in source leaves. | elucidating the role of viral genes in transgenic plants revealed that the movement protein (mp) from tobacco mosaic virus is responsible for altered carbohydrate allocation in tobacco and potato plants. to study whether this is a general feature of viral mps, the movement protein mp17 of potato leafroll virus (plrv), a phloem-restricted luteovirus, was constitutively expressed in tobacco plants. transgenic lines were strongly reduced in height and developed bleached and sometimes even necrotic ... | 1997 | 9418046 |
| mutational analysis of the potato virus y 5' untranslated region for alteration in translational enhancement in tobacco protoplasts. | the 185 nucleotide 5' untranslated region (5'utr) of potato virus y ordinary strain (pvy-o) showed translation-enhancing activity on the beta-glucuronidase (gus) gene in tobacco protoplasts. mutational analysis of the 5'utr was done to find sequence motifs necessary for the enhancement. deletions within the 1-130 nucleotide region of 5'utr stimulated the gus expression in some cases, while the gus activity declined with deletions in the 131-185 nucleotide region. the results indicated that the l ... | 1997 | 9438996 |
| simultaneous detection of cucumber mosaic virus, tomato mosaic virus and potato virus y by flow cytometry. | the simultaneous detection is described of cucumber mosaic virus (cmv), potato virus y (pvy) and tomato mosaic virus (tomv) by flow cytometry. extracts from leaves of healthy and cmv or pvy infected plants were incubated with latex particles, each with a diameter of 3 microm. extracts from tomv infected or uninfected plants, however, were incubated with particles, each with a diameter of 6 microm. beads were washed and incubated in succession with primary and secondary antibodies, the latter lab ... | 1997 | 9504759 |
| expression of a cdna encoding phytolacca insularis antiviral protein confers virus resistance on transgenic potato plants. | to develop an antiviral agent and virus-resistant plants, a cdna clone encoding phytolacca insularis antiviral protein (pip) was isolated from a cdna library constructed with poly(a)+ rna purified from leaves of p. insularis. the pip cdna contains an open reading frame encoding 307 amino acids. the deduced amino acid sequence includes a putative signal sequence of 22 amino acids at the n-terminus. the amino acid sequence of pip shares 84% homology with that of the pokeweed antiviral protein (pap ... | 1997 | 9509425 |
| a hypersensitive response-like mechanism is involved in resistance of potato plants bearing the ry(sto) gene to the potyviruses potato virus y and tobacco etch virus. | potato plants carrying the ry(sto) gene from solanum stoloniferum are extremely resistant to a number of potyviruses, but it is not known at what stage of infection the resistance is expressed. the resistance may be due to ry(sto) or to a closely linked gene. in this investigation, we used potato virus y (pvy) and a tobacco etch virus construct that encodes beta-glucuronidase (tev-gus) to monitor virus infections of potato plants. systemic spread of either virus in resistant potato plants was no ... | 1998 | 9460939 |
| transgenic plants expressing potato virus x orf2 protein (p24) are resistant to tobacco mosaic virus and ob tobamoviruses. | the p24 protein, one of the three proteins implicated in local movement of potato virus x (pvx), was expressed in transgenic tobacco plants (nicotiana tabacum xanthi d8 nn). plants with the highest level of p24 accumulation exhibited a stunted and slightly chlorotic phenotype. these transgenic plants facilitate the cell-to-cell movement of a mutant of pvx that contained a frameshift mutation in p24. upon inoculation with tobacco mosaic virus (tmv), the size of necrotic local lesions was signific ... | 1998 | 9420280 |
| potato virus y group c isolates are a homogeneous pathotype but two different genetic strains. | potato virus y group c isolates (pvyc) have been characterized according to biological, molecular and genetic criteria. two genetic strains, pvyc1 and pvyc2, were identified on the basis of genetic distances (among them and other pvy strains), host range (ability or inability to infect pepper), mab response (elisa recognition with mab 10e3) and coat protein processing site. some characteristics, such as aphid transmission and elisa using other mabs, did not correlate with classification into the ... | 1998 | 9714255 |
| potato virus a detection by reverse transcription-polymerase chain reaction. | simple and reliable procedure for sample preparation and reverse transcription-polymerase chain reaction (rt-pcr) detection of potato virus a (pva) is described. pva-specific primers used in the rt-pcr defined a target sequence of 321 bp and did not produce amplification product(s) with potato virus y. | 1998 | 9770075 |
| strain specific recombinant antibodies to potato virus y potyvirus. | single chain fv antibody fragments have been selected from a synthetic phage-antibody library following three and four rounds of affinity selection with purified potato virus y, common strain (pvy(o)). the selected fragments were highly specific for pvy and detected seven out of nine isolates of pvy(o) whilst failing to detect three isolates of pvy(n) and 12 isolates of pvy(ntn). nucleotide sequence of the scfv genes showed the variable heavy fragments belonged to the human vh4 family, whilst th ... | 1998 | 9779619 |
| localization of the p1 protein of potato y potyvirus in association with cytoplasmic inclusion bodies and in the cytoplasm of infected cells. | the n-terminal p1 proteinase of potato virus y (ordinary strain group isolate pvy-o) was expressed in e. coli. antiserum was raised against the expressed protein and used to detect the viral proteins in infected tobacco leaf tissue by western blotting and by electron microscopy with immunogold labelling. in the immunogold localization studies p1 protein was detected in association with the cytoplasmic inclusion bodies characteristic of pvy infections and in the cytoplasm of the infected plant ce ... | 1998 | 9780035 |
| resistance in plants transformed with the p1 or p3 gene of tobacco vein mottling potyvirus. | tobacco plants were transformed with genes encoding the tobacco vein mottling potyvirus (tvmv) p1 or p3 protein. when compared with vector-transformed or p1 transgenic lines, seedlings of p3 transgenic lines (except a low expressor line) developed poorly, suggesting a detrimental effect of p3 on the plant. all p1 and p3 transgenic lines were protected against the homologous tvmv strain and showed variable proportions of two resistance phenotypes: asymptomatic plants or symptomatic plants that re ... | 1998 | 9820159 |
| viral pathogenicity determinants are suppressors of transgene silencing in nicotiana benthamiana. | post-transcriptional gene silencing (ptgs) of a green fluorescent protein (gfp) transgene is suppressed in nicotiana benthamiana plants infected with potato virus y (pvy) or with cucumber mosaic virus (cmv), but not in plants infected with potato virus x (pvx). by expressing pvy and cmv-encoded proteins in a pvx vector we have shown that the viral suppressors of gene silencing are the hcpro of pvy and the 2b protein of cmv. the hcpro acts by blocking the maintenance of ptgs in tissues where sile ... | 1998 | 9822616 |
| rflp mapping of the whole genome of ten viral isolates representative of different biological groups of potato virus y. | ten pvy isolates representative of four pvy groups (yn, yntn, yn-w, yo), differing by their ability to induce reactions of vein necrosis on tobacco and tuber necrosis on potato, were studied in order to research the regions of the viral genome involved in these necrosis phenomena. the whole genome of these isolates was amplified in two fragments (4,063 and 5,670 nucleotides) and was subjected to a restriction fragment length polymorphism (rflp) study. in the first 4,063 nucleotides of the pvy ge ... | 1998 | 9856095 |
| mutations in the potyvirus helper component protein: effects on interactions with virions and aphid stylets. | mutations of k --> e in the highly conserved 'kitc' motif of the potyvirus helper component (hc) protein result in loss of hc function in aphid transmission, presumably because of inability to interact with virions, stylets or both. in this study we show that hc of potato virus c (pvc), a naturally occurring variant of potato virus y (pvy) that has the k --> e mutation, lacks the ability to be retained in stylets, whereas pvy hc is retained. the k --> e mutation in either pvc or a site-directed ... | 1998 | 9880030 |
| affinity purification of hc-pro of potyviruses with ni2+-nta resin. | the hc-pro of zucchini yellow mosiac virus (zymv) was found to bind to ni2+-nta resin with or without his-tagging. the binding stringency was similar to that observed in proteins with a zinc finger motif like the hc-pro. using this characteristic we developed an efficient and rapid method (2-3 h) for purification of the hc-pro of several potyviruses. a dominant protein of about 150 kda was extracted and identified as the hc-pro of zymv by means of immunoblotting. about 150 microg of hc-pro were ... | 1998 | 9923736 |
| detection of potato virus y p1 protein in infected cells and analysis of its cleavage site. | the p1 protein is liberated from the n-terminal region of the potyviral polyprotein by cleavage depending on its own autoproteolytic activity. existence of the 32-kda p1 protein in tobacco plants infected with potato virus y ordinary strain (pvy-o) was detected by an antiserum against a recombinant pvy-o p1 protein. in vivo analysis using tobacco protoplasts confirmed that the phe284-ser285 was the cleavage site separating the p1 protein from the pvy-o polyprotein. phe284 was indispensable for p ... | 1998 | 9532800 |
| separation of slovenian isolates of pvy(ntn) from the north american isolates of pvy(n) by a 3-primer pcr. | the potato tuber ringspot necrosis isolate of potato virus y (pvy(ntn)) is a recently recognized and highly aggressive isolate of the pvy(n) group of strains. in order to screen specifically sources of resistance to pvy(ntn) a method to separate pvy(ntn) from pvy(n) is needed. to achieve this, 61 isolates from 13 imported and locally developed potato cultivars in slovenia were studied. on the basis of the reactions in indicator plants nicotiana tabacum cv. samsun and solanum brachycarpum and wit ... | 1998 | 9628222 |
| examination of the leaf-drop symptom of virus-infected potato using anther culture-derived haploids. | abstract necrotic lesions and vein necrosis characteristic of the hypersensitive response (hr) controlled by the dominant resistance gene ny develop in potato cv. pito after infection with potato virus y ordinary strain (pvy masculine) at a low temperature (16/18 degrees c night/day). in contrast, at high temperatures (19/24 degrees c night/day), large coalesced lesions develop in the lower infected leaves, which wither and remain hanging from stems forming the leaf-drop symptom; mosaic symptoms ... | 1998 | 18944819 |
| tissue culture methods for the screening and analysis of putative virus-resistant transgenic potato plants. | abstract following regeneration, putative virus-resistant transgenic plants are usually transferred from tissue culture to a greenhouse or growth chamber to screen for resistance to infection and disease development using mechanical, graft, or insect vector inoculation methods. to reduce initial screening costs and time, we developed mechanical and graft inoculation methods suitable for tissue culture use. the in vitro methods were validated by comparing them with similar greenhouse screens usin ... | 1998 | 18944923 |
| helper component mutations in nonconserved residues associated with aphid transmission efficiency of a pepper isolate of potato virus y. | abstract the aphid transmission properties of a pepper isolate of potato virus y belonging to the pathotype 1-2 (pvy 1-2) have been characterized. pvy 1-2 was not transmitted in plant-to-plant experiments, although purified virus particles were efficiently transmitted when supplemented with heterologous helper component (hc) of the transmissible isolate pvy 0 at through membrane acquisition assays, indicating that its coat protein was functional in transmission. additionally, virions of pvy 1-2 ... | 1999 | 18944642 |
| a single amino acid change in viral genome-associated protein of potato virus y correlates with resistance breaking in 'virgin a mutant' tobacco. | abstract tobacco cultivar virgin a mutant (vam) is reported to have the recessive potyvirus resistance gene va. varied levels of resistance were observed in vam plants inoculated with japanese potato virus y (pvy) isolates. vam was highly resistant to most of the pvy isolates tested and tolerant to three necrotic strain isolates of pvy-t. based on data obtained from tissue printing and press blotting, the resistance appeared to be mainly at the level of cell-to-cell movement. pvy replicated in v ... | 1999 | 18944784 |
| potyvirus helper component-proteinase self-interaction in the yeast two-hybrid system and delineation of the interaction domain involved. | using the yeast two-hybrid system, a screen was performed for possible interactions between the proteins encoded by the 5' region of potyviral genomes [p1, helper component-proteinase (hc-pro), and p3]. a positive self-interaction involving hc-pro was detected with lettuce mosaic virus (lmv) and potato virus y (pvy). the possibility of heterologous interaction between the hc-pro of lmv and of pvy was also demonstrated. no interaction involving either the p1 or the p3 proteins was detected. a ser ... | 1999 | 10329571 |
| gene silencing-mediated resistance in transgenic tobacco plants carrying potato virus y coat protein gene. | unlike other pathogens, plant viruses are hardly controlled by chemical agents. potato virus y (pvy) is distributed around the world, and causes a great loss economically. in an attempt to minimize the damage by viruses, the pvy coat protein (cp) gene was introduced into tobacco by agrobacterium-mediated transformation. a significant proportion of the transgenic plants displayed resistance to pvy and showed substantially decreased cp transgene expression at both protein and steady-state mrna lev ... | 1999 | 10515600 |
| effect of mutations within the cys-rich region of potyvirus helper component-proteinase on self-interaction. | the first approximately 60 amino acids of the n-terminal part of the potyvirus helper component-proteinase (hc-pro) include highly conserved residues comprising a cys-rich region. in the present study, the domain in potato virus y sufficient for self-interaction was mapped using the yeast two-hybrid system to the 83 n-terminal amino acids of hc-pro. mutations in the conserved his and two cys residues within the cys-rich region have a strong debilitating effect on self-interaction when introduced ... | 1999 | 10580041 |
| the use of cysteine proteinase inhibitors to engineer resistance against potyviruses in transgenic tobacco plants. | as the processing mechanism of all known potyviruses involves the activity of cysteine proteinases, we asked whether constitutive expression of a rice cysteine proteinase inhibitor gene could induce resistance against two important potyviruses, tobacco etch virus (tev) and potato virus y (pvy), in transgenic tobacco plants. tobacco lines expressing the foreign gene at varying levels were examined for resistance against tev and pvy infection. there was a clear, direct correlation between the leve ... | 1999 | 10585723 |
| rna-dna interactions and dna methylation in post-transcriptional gene silencing. | post-transcriptional gene silencing (ptgs) is a homology-dependent process that reduces cytoplasmic rna levels. in several experimental systems, there is also an association of ptgs with methylation of dna. to investigate this association, we used plants carrying a transgene encoding the green fluorescent protein (gfp). gene silencing was induced using potato virus x rna vectors carrying parts of the coding sequence or the promoter of the gfp transgene. in each instance, homology-based, rna-dire ... | 1999 | 10590159 |
| deletion of a large genomic segment in tobacco varieties that are resistant to potato virus y (pvy). | recessive alleles (va, va1, va2, etc) of the tobacco va locus confer resistance to potato virus y (pvy). to elucidate the mechanism underlying this resistance, we attempted to identify randomly amplified polymorphic (rapd) markers that reveal polymorphism between two nearly isogenic lines (nils) that differ in their susceptibility to pvy. using each of 500 primers and 800 pairs of primers, we identified over 100 rapd fragments that differed between the nils. we applied these rapd primers or prim ... | 1999 | 10628866 |
| development of a caps marker for the pvr4 locus: a tool for pyramiding potyvirus resistance genes in pepper. | the pvr4 resistance gene in pepper confers a complete resistance to the three pathotypes of potato virus y (pvy) and to pepper mottle virus (pepmov). in order to use this gene in a marker-assisted selection (mas) program and to permit the pyramiding of several potyvirus resistance genes in the same cultivar, tightly linked amplified fragment length polymorphism (aflp) markers were obtained by the bulked segregant analysis method. eight linked aflp markers were mapped in an interval from 2.1 +/- ... | 1999 | 10659777 |
| partial antigenic characterization of different potato virus y ntn strain isolates. | eight isolates of potato virus y ntn strain (pvy-ntn) of different origin were studied by means of monoclonal antibodies (mabs) in non-competitive and competitive enzyme-linked immunosorbent assay (elisa), and by immunoblot analysis of the viral coat protein (cp). as the mabs reacted with the denatured viral cp, their epitopes must be continuous. the elisa data demonstrate that the epitopes are topologically different. the epitopes may be located on the n-terminal part of cp as showed its partia ... | 1999 | 10825930 |
| comparative genetics of disease resistance within the solanaceae. | genomic positions of phenotypically defined disease resistance genes (r genes) and r gene homologues were analyzed in three solanaceous crop genera, lycopersicon (tomato), solanum (potato), and capsicum (pepper). r genes occurred at corresponding positions in two or more genomes more frequently than expected by chance; however, in only two cases, both involving phytophthora spp., did genes at corresponding positions have specificity for closely related pathogen taxa. in contrast, resistances to ... | 2000 | 10835406 |
| transgenic or plant expression vector-mediated recombination of plum pox virus. | different mutants of an infectious full-length clone (p35ppv-nat) of plum pox virus (ppv) were constructed: three mutants with mutations of the assembly motifs rq and df in the coat protein gene (cp) and two cp chimeras with exchanges in the cp core region of zucchini yellow mosaic virus and potato virus y. the assembly mutants were restricted to single infected cells, whereas the ppv chimeras were able to produce systemic infections in nicotiana benthamiana plants. after passages in different t ... | 2000 | 10906199 |
| an ry-mediated resistance response in potato requires the intact active site of the nia proteinase from potato virus y. | ry confers extreme resistance to all strains of potato virus y (pvy). to identify the elicitor of the ry-mediated resistance against pvy in potato, we expressed each of the pvy-encoded proteins in leaves of pvy-resistant (ry) and -susceptible (ry) plants. for most of the proteins tested, there was no evident response. however, when the nia proteinase was expressed in leaves of ry plants, there was a hypersensitive response (hr). proteinase active site mutants failed to induce the ry-mediated res ... | 2000 | 10972891 |
| analysis of variability of p1 gene region of n strain of potato virus y using temperature-gradient gel electrophoresis and dna heteroduplex analysis. | reaction conditions specific for reverse taranscription-polymerase chain reaction (rt-pcr) of potato virus y strain ntn (pvyntn) were used to amplify a 394 bp fragment of the p1 gene from selected pvy isolates with the aim to study the pvy variability within this genomic region. the p1 gene fragment from the nicola isolate (nicola p1/1 clone) was sequenced and characterized by temperature-gradient gel electrophoresis (tgge). the nicola p1/1 clone differed from that from the hungarian isolate by ... | 2000 | 10989691 |
| some epidemiological approaches to the control of aphid-borne virus diseases in seed potato crops in northern europe. | an account is given of progress during the last 30 years in knowledge of the epidemiology of diseases caused by aphid-borne viruses in seed potato production areas of northern europe. during this period, potato leafroll virus (plrv) and strains of potato virus y (pvy(o), pvy(n)) were consistently the most prevalent and harmful. the main factors influencing spread involve the amount of initial virus inoculum in seed crops, agricultural practices in relation to seed potato production, the status o ... | 2000 | 11137160 |
| barrier crops as a cultural control measure of non-persistently transmitted aphid-borne viruses. | barrier crops have been used since the early 1950s as a cultural control strategy for reducing the spread of non-persistently transmitted aphid-borne viruses. since then, this strategy has been investigated by several authors, resulting in a wide range of divergent conclusions on its effectiveness. in a series of field and laboratory experiments carried out in central spain during 1995-1998, we investigated the efficacy and mode of action of various barrier crops for reducing the spread of potat ... | 2000 | 11137174 |
| molecular characterization of a new potyvirus infecting sunflower. | we have sequenced 1873 nucleotides from the 3'-end region of a sunflower potyvirus genome including the 3'-nib protein coding region (813 nucleotides), the entire coat protein coding region (807 nucleotides) and 3'-ncr (253 nucleotides), excluding the poly (a) tail. amino acids identity of the whole cp between the sunflower virus and potyvirus members ranged from 49.5% (scmv) to 81.5% (pvy-nsnr), and the core ranged from 55% (tvmv) to 87% (pvy-nsnr; pepmov). the 3'-ncr nucleotides showed 38.7% h ... | 2000 | 11205115 |
| constitutive expression of interferon-induced human mxa protein in transgenic tobacco plants does not confer resistance to a variety of rna viruses. | mxa is a key component in the interferon-induced antiviral defense in humans. after viral infections, mxa is rapidly induced and accumulates in the cytoplasm. the multiplication of many rna viruses, including all bunyaviruses tested so far, is inhibited by mxa. these findings prompted us to express mxa in plants in an attempt to create resistance to tospoviruses. here, we report the generation of transgenic tobacco plants that constitutively express mxa under the control of the 35 s cauliflower ... | 2000 | 11206971 |
| virus strain discrimination using recombinant antibodies. | most routine testing for plant viruses is currently carried out using monoclonal and polyclonal antibodies. traditional methods of antibody production however can be time consuming and require the use of expensive cell culture facilities. recombinant antibody technology however is starting to make an impact in this area, enabling the selection of antibody fragments in a few weeks compared with the many months associated with traditional methods and requires only basic microbiological facilities. ... | 2000 | 11360835 |
| mutations in the coat protein gene of plum pox virus suppress particle assembly, heterologous encapsidation and complementation in transgenic plants of nicotiana benthamiana. | two different motifs in the coat protein (cp) of plum pox virus (ppv) (r(3015)q(3016), d(3059)) were mutated by replacing the respective amino acids with others possessing different chemical properties. the mutated cp genes were introduced into an infectious full-length clone of ppv (p35ppv-nat) to investigate their influence on systemic infection of transgenic wild-type ppv cp-expressing and non-transgenic plants of nicotiana benthamiana. all mutants failed to establish systemic infections in n ... | 2000 | 10675394 |
| aphid transmission studies using helper component proteins of potato virus y expressed from a vector derived from potato virus x. | the genes encoding the helper component (hc) proteins of two strains of potato virus y (pvy) were cloned and the proteins expressed from a vector derived from potato virus x (pvx). the expressed hc contained six n-terminal histidine residues to facilitate purification by metal affinity chromatography. approximately 2-4 microg/g of purified hc was obtained from leaves of nicotiana benthamiana plants systemically infected by recombinant pvx. preparations of the hc protein derived from pvy ordinary ... | 2000 | 10725440 |
| transgenic resistance to pvy(o) associated with post-transcriptional silencing of p1 transgene is overcome by pvy(n) strains that carry highly homologous p1 sequences and recover transgene expression at infection. | resistance to potato virus y (pvy) has been obtained in our previous studies through expression of the pvy p1 gene in sense or antisense orientation in potato cv. pito. in the present study, the mechanism and strain specificity of the resistance were analyzed. several features including low steady-state p1 mrna expression in the resistant p1 plants indicated that resistance was based on post-transcriptional gene silencing (ptgs). resistance was specific to pvy(o) isolates, the pvy strain group f ... | 2000 | 10755299 |
| recessive and dominant genes interfere with the vascular transport of potato virus a in diploid potatoes. | resistance to potato virus a (pva) was examined in a diploid cross involving solanum tuberosum subsp. andigena as a resistance source. hypersensitive resistance (hr) to pva cosegregated with extreme resistance (er) to potato virus y conferred by the dominant gene ry(adg) on chromosome xi. hence, hr to pva was controlled by a novel, dominant resistance gene closely linked to ry(adg), or ry(adg) recognized both viruses but conferred a different type of resistance to each virus. the hr prevented sy ... | 2000 | 10755303 |
| complementation of the movement-deficient mutations in potato virus x: potyvirus coat protein mediates cell-to-cell trafficking of c-terminal truncation but not deletion mutant of potexvirus coat protein. | the cell-to-cell movement of the gus-tagged potato virus x (pvx) coat protein (cp) movement-deficient mutant was restored by potyviral cps of potato virus a (pva) and potato virus y (pvy) in nicotiana benthamiana leaves in transient cobombardment experiments. viral cell-to-cell movement of pvx cp mutant was complemented in nicotiana tabacum cv. sr1 transgenic plants expressing pvy cp: pvx rna and polymerase were detected in the pvx cp mutant-inoculated leaves of transgenic plants. these findings ... | 2000 | 10772977 |
| duplex rt-pcr: reagent concentrations at reverse transcription stage affect the pcr performance. | test conditions for the simultaneous detection of potato leafroll virus (plrv) and potato virus y (pvy) in dormant tubers and leaves by reverse transcription-polymerase chain reaction (rt-pcr) were optimized. various factors optimized at the reverse transcription (rt) stage rather than at the amplification (pcr) stage affected the outcome. in the simplex rt-pcr a onefold dntps concentration (0.5 mm) was sufficient in yielding a plrv or pvy band. in contrast, the duplex rt-pcr required a minimum ... | 2000 | 10785287 |
| a hypercycle theory of proliferation of viruses and resistance to the viruses of transgenic plant. | a set of dynamical equations for the proliferation of two typical viruses tmv and pvy has been derived from the reaction equations describing their replication, assembly and translation. these equations can be seen as the generalization of hypercycle theory to the system. the quantitative explanation on the phenomena of proliferation of plant virus and the mechanism of resistance to the disease of transgenic plant is offered. the phenomenon of specific cessation of minus-strand rna accumulation ... | 2000 | 10816368 |
| compositional analysis of tubers from insect and virus resistant potato plants. | genetically modified potato plants that are resistant to the colorado potato beetle, plus either the potato leaf roll virus or potato virus y, have recently been commercialized. as part of the safety assessment for plants produced by modern biotechnology, the composition of the food/feed must be compared to that of the food/feed produced by an equivalent plant variety from a conventional source. the composition of important nutritional and antinutritional factors in tubers produced by virus- and ... | 2000 | 11312768 |
| regulation of carbohydrate partitioning during the interaction of potato virus y with tobacco. | abstract to test whether carbohydrates may play a signalling function during plant pathogenesis, we investigated the interaction between tobacco and potato virus y (pvy(n)). four days after pvy(n) infection, leaves started to accumulate soluble sugars and leaf photosynthesis decreased. the accumulation of soluble sugars was accompanied by an induction of cell wall invertase and a gradual decrease in the sucrose-to-hexose ratio. in parallel to changes in carbohydrate metabolism and photosynthesis ... | 2000 | 20572950 |
| molecular characterization of potato virus v genomes from europe indicates limited spatiotemporal strain differentiation. | abstract because there were no previous reports on the molecular characterization of potato virus v (pvv, genus potyvirus, family potyviridae), the complete genomic sequence of pvv isolate dv42 was determined. the length of the single-stranded messenger-polarity rna genome was 9,851 nt (nucleotides), followed by a poly(a) tail. the genome contained a 5'-terminal nontranslated region (5'-ntr; 204 nt), a single open reading frame (nucleotides 205-9406; 3,067 amino acids), and a 3'-ntr that was unu ... | 2000 | 18944596 |
| sense- and antisense-mediated gene silencing in tobacco is inhibited by the same viral suppressors and is associated with accumulation of small rnas. | antisense-mediated gene silencing (asgs) and posttranscriptional gene silencing (ptgs) with sense transgenes markedly reduce the steady-state mrna levels of endogenous genes similar in transcribed sequence. rnase protection assays established that silencing in tobacco plants transformed with plant-defense-related class i sense and antisense chitinase (chn) transgenes is at the posttranscriptional level. infection of tobacco plants with cucumber mosaic virus strain fn and a necrotizing strain of ... | 2001 | 11353866 |
| evidence for rna-mediated defence effects on the accumulation of potato leafroll virus. | in plants infected with potato leafroll virus (plrv), or other luteoviruses, infection is very largely confined to cells in the vascular system. even in tobacco plants transformed with plrv full-length cdna, in which all mesophyll cells should synthesize infectious plrv rna transcripts, only a minority of the mesophyll cells accumulate detectable amounts of virus. we have explored this phenomenon further by transforming a better plrv host, nicotiana benthamiana, with the same transgene, by super ... | 2001 | 11714988 |
| a mosaic disease of senna hirsuta induced by a potyvirus in nigeria. | a virus inducing mosaic and severe leaf malformation, isolated from senna hirsuta in nigeria, was studied. the virus had a rather narrow host range, infecting a few species in caesalpinaceae, chenopodiaceae and fabaceae families. the virus was widespread in southern nigeria with prevalence ranging from 74% to 86.4% in some locations. it was transmitted mechanically and in a non-persistent manner by myzuspersicae, aphis craccivora and a. spiraecola. there was no evidence of transmission by seeds. ... | 2001 | 11719985 |