The Experts below are selected from a list of 171 Experts worldwide ranked by ideXlab platform
D J Robinson - One of the best experts on this subject based on the ideXlab platform.
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umbraVirus encoded proteins both stabilize heterologous viral rna and mediate its systemic movement in some plant species
2001Co-Authors: Eugene V Ryabov, D J Robinson, Michael TalianskyAbstract:The proteins encoded by open reading frame 3 (ORF3) of the umbraViruses pea enation mosaic Virus-2 and tobacco mottle Virus, like that of Groundnut Rosette Virus, mediated the movement of viral RNA through the phloem of infected Nicotiana benthamiana or N. clevelandii plants when they were expressed from chimeric tobacco mosaic Virus in place of the coat protein. However, these chimeras did not move systemically in N. tabacum. In lysates of N. benthamiana or N. tabacum protoplasts, the chimeric RNAs were more stable than was RNA of tobacco mosaic Virus lacking the coat protein gene. The chimeric Viruses also protected the latter in trans, suggesting that the ORF3 proteins can increase the stability of heterologous viral RNA. Umbraviral ORF3 proteins contain a conserved arginine-rich domain, and the possible roles of this motif in the functions of the proteins are discussed.
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Groundnut Rosette disease Virus complex biology and molecular biology
2000Co-Authors: Michael Taliansky, D J Robinson, A F MurantAbstract:Publisher Summary This chapter focuses on the cause of Rosette disease of Groundnut in which the umbraVirus Groundnut Rosette Virus (GRV) depends on Groundnut Rosette assistor Virus (GRAV) for transmission by Aphis craccivora . The GRV/GRAV complex is, especially interesting, because the main cause of Rosette disease symptoms in Groundnut is a third component, a satellite RNA, which depends on GRV for its replication but on GRAV for its encapsidation and transmission by aphids. There are two major symptom variants, chlorotic Rosette and green Rosette with considerable variation within each type. Both the chlorotic and green forms of the disease make plants severely stunted, with shortened internodes and reduced leaf size. In chlorotic Rosette, the leaves are bright yellow, usually with a few green islands. The biological properties of GRAV, which replicates autonomously in plants, are typical of a luteoVirus and GRAV is therefore classified within the family Luteoviridae .
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epidemiology of Groundnut Rosette Virus disease current status and future research needs
1998Co-Authors: Rayapati A Naidu, D J Robinson, H Bottenberg, P Subrahmanyam, F M Kimmins, J M ThreshAbstract:Rosette is the most destructive Virus disease of Groundnut in sub-Saharan Africa. It is caused by a complex of Groundnut Rosette assistor Virus, Groundnut Rosette umbraVirus and its satellite RNA. The disease appears to be indigenous to Africa. The disease is thought to have spread to the introduced Groundnut from indigenous host plants. Unresolved issues of importance include the nature of the primary source(s) of inoculum, the means of survival of the disease and vector during unfavourable periods, and the distances over which the aphid vector can disperse and disseminate Virus. It is suggested that the ecology and epidemiology of Rosette disease need further investigation. It is also suggested that progress can be made by developing a co-ordinated multi-disciplinary research programme, and by making full use of the latest techniques. It is concluded that this information could prove useful for explaining the sporadic disease epidemics that cause serious crop losses and occasional total crop failure, and would facilitate the development
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two distinct mechanisms of transgenic resistance mediated by Groundnut Rosette Virus satellite rna sequences
1998Co-Authors: Michael Taliansky, Eugene V Ryabov, D J RobinsonAbstract:Transformation of Nicotiana benthamiana with full-length sequences of a mild variant of the Groundnut Rosette Virus (GRV) satellite RNA (sat-RNA) yielded plants that did not produce symptoms when inoculated with GRV and a virulent sat-RNA. Two different resistance mechanisms operated in different transformed lines. In the first, plants contained high levels of transcript RNA, and replication of both sat-RNA and GRV genomic RNA was inhibited. This mechanism is analogous to the down-regulation of GRV genomic and sat-RNA replication in infections containing the mild sat-RNA, and indeed infection of sat-RNA transgenic plants with GRV was shown to lead to liberation of unit-length sat-RNA from transgene transcripts. In the second resistance mechanism, plants contained low transcript RNA levels, and replication of sat-RNA but not of GRV genomic RNA was inhibited. These plants were also resistant to infection by potato Virus X derivatives containing GRV sat-RNA sequences. This mechanism is an example of homology-dependent gene silencing or cosuppression. Resistant plants were also produced by transformation with sequences representing only the 5′ terminal one-third of the mild sat-RNA; the mechanism of resistance in these plants was of the cosuppression type. Additional keywords: Groundnut Rosette disease.
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trans acting untranslated elements of Groundnut Rosette Virus satellite rna are involved in symptom production
1997Co-Authors: Michael Taliansky, D J RobinsonAbstract:Isolates of Groundnut Rosette umbraVirus (GRV) contain a satellite RNA (sat-RNA), about 900 nucleotides (nt) in length, different variants of which are responsible for the symptoms of different forms of Rosette disease in Groundnuts and, in the particular instance of sat-RNA YB3b, for the production of yellow blotch symptoms in Nicotiana benthamiana. Sat-RNA YB3b does not affect the accumulation of GRV genomic or subgenomic RNAs in infected plants. Replication of sat-RNA YB3b and induction of yellow blotch symptoms do not require the production of any sat-RNA-encoded proteins. Experiments with deletion mutants identified three functional untranslated elements in sat-RNA YB3b. One (designated R) comprises nt 47-281, is essential for sat-RNA replication and appears to be cis-acting. The other two (designated A and B) comprise nt 280-470 and 629-849, respectively, are both involved in yellow blotch symptom production and can act in trans. Element A contains the determinant that is unique to sat-RNA YB3b. The process of symptom induction by sat-RNA YB3b apparently involves a novel type of specific interaction of two untranslated RNA elements, which can complement each other, with a host factor or factors.
Michael Taliansky - One of the best experts on this subject based on the ideXlab platform.
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umbraVirus encoded movement protein induces tubule formation on the surface of protoplasts and binds rna incompletely and non cooperatively
2001Co-Authors: Kulpash M Nurkiyanova, Eugene V Ryabov, N O Kalinina, Yongchang Fan, Igor A Andreev, A G Fitzgerald, Peter Palukaitis, Michael TalianskyAbstract:Various functions of the cell-to-cell movement protein (MP) of Groundnut Rosette Virus (GRV) were analysed. The GRV ORF4-encoded protein was shown by immunofluorescence microscopy to generate tubular structures that protrude from the surface of the protoplast. The protein encoded by ORF4 was assessed also for RNA-binding properties. This protein was tagged at its C terminus with six histidine residues, produced in Escherichia coli using an expression vector and purified by affinity chromatography. Gel retardation analysis demonstrated that, in contrast to many other viral MPs, including the 3a MP of Cucumber mosaic Virus (CMV), the ORF4-encoded protein bound non-cooperatively to viral ssRNA and formed complexes of low protein:RNA ratios. Competition binding experiments showed that the ORF4-encoded protein bound to both ssRNA and ssDNA without sequence specificity, but did not bind to dsDNA. UV cross-linking and nitrocellulose membrane-retention assays confirmed that both the GRV and the CMV MPs formed complexes with ssRNA and that these complexes showed similar stability in NaCl. Probing the MP–RNA complexes by atomic force microscopy demonstrated that the ORF4-encoded protein bound RNA incompletely, leaving protein-free RNA segments of varying length, while the CMV 3a protein formed highly packed complexes. The significance of the two properties of limited RNA binding and tubule formation of the umbraviral MP is discussed.
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umbraVirus encoded proteins both stabilize heterologous viral rna and mediate its systemic movement in some plant species
2001Co-Authors: Eugene V Ryabov, D J Robinson, Michael TalianskyAbstract:The proteins encoded by open reading frame 3 (ORF3) of the umbraViruses pea enation mosaic Virus-2 and tobacco mottle Virus, like that of Groundnut Rosette Virus, mediated the movement of viral RNA through the phloem of infected Nicotiana benthamiana or N. clevelandii plants when they were expressed from chimeric tobacco mosaic Virus in place of the coat protein. However, these chimeras did not move systemically in N. tabacum. In lysates of N. benthamiana or N. tabacum protoplasts, the chimeric RNAs were more stable than was RNA of tobacco mosaic Virus lacking the coat protein gene. The chimeric Viruses also protected the latter in trans, suggesting that the ORF3 proteins can increase the stability of heterologous viral RNA. Umbraviral ORF3 proteins contain a conserved arginine-rich domain, and the possible roles of this motif in the functions of the proteins are discussed.
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umbraVirus gene expression helps potato leafroll Virus to invade mesophyll tissues and to be transmitted mechanically between plants
2001Co-Authors: Eugene V Ryabov, H. Barker, Gillian Fraser, M A Mayo, Michael TalianskyAbstract:Potato leafroll Virus (PLRV) was mechanically transmissible when inocula also contained the umbraVirus Pea enation mosaic Virus-2 (PEMV-2). In plants infected with PLRV and PEMV-2, PLRV accumulated in clusters of mesophyll cells in both inoculated and systemically infected leaves. No transmissions were obtained by coinoculation with Potato Virus Y, Potato Virus X (PVX), Tobacco mosaic Virus, or Cucumber mosaic Virus (CMV), although PLRV was transmissible from mixtures with CMV(ORF4) (a recombinant that contained the movement protein (MP) gene of the umbraVirus Groundnut Rosette Virus (GRV) in place of the CMV MP gene). In contrast, neither a recombinant PVX that expressed GRV MP nor a mutant of CMV(ORF4), in which the CMV 2b gene was untranslatable, was able to help PLRV transmission. Possibly both a cell-to-cell movement function and counterdefense mechanisms such as those that block posttranscriptional gene silencing are involved in movement of PLRV within plants and its mechanical transmission between plants.
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Groundnut Rosette disease Virus complex biology and molecular biology
2000Co-Authors: Michael Taliansky, D J Robinson, A F MurantAbstract:Publisher Summary This chapter focuses on the cause of Rosette disease of Groundnut in which the umbraVirus Groundnut Rosette Virus (GRV) depends on Groundnut Rosette assistor Virus (GRAV) for transmission by Aphis craccivora . The GRV/GRAV complex is, especially interesting, because the main cause of Rosette disease symptoms in Groundnut is a third component, a satellite RNA, which depends on GRV for its replication but on GRAV for its encapsidation and transmission by aphids. There are two major symptom variants, chlorotic Rosette and green Rosette with considerable variation within each type. Both the chlorotic and green forms of the disease make plants severely stunted, with shortened internodes and reduced leaf size. In chlorotic Rosette, the leaves are bright yellow, usually with a few green islands. The biological properties of GRAV, which replicates autonomously in plants, are typical of a luteoVirus and GRAV is therefore classified within the family Luteoviridae .
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host specific cell to cell and long distance movements of cucumber mosaic Virus are facilitated by the movement protein of Groundnut Rosette Virus
1999Co-Authors: Eugene V Ryabov, Peter Palukaitis, I M Roberts, Michael TalianskyAbstract:The cucumoVirus, cucumber mosaic Virus (CMV), requires both the 3a movement protein (MP) and the capsid protein (CP) for cell-to-cell movement. Replacement of the MP of CMV with the MP of the umbraVirus, Groundnut Rosette Virus (GRV), which does not encode a CP, resulted in a hybrid Virus, CMV(ORF4), which could move cell to cell in Nicotiana tabacum and long distance in N. benthamiana. After replacement of the CMV CP in CMV(ORF4) with the gene encoding the green fluorescent protein (GFP), the hybrid Virus, CMV(ORF4.GFP), expressing both the GRV MP and the GFP, could move cell to cell but not systemically in either Nicotiana species. Immunoelectron microscopic analysis of cells infected by the hybrid Viruses showed different cellular barriers in the vasculature preventing long-distance movement of CMV(ORF4) in N. tabacum and CMV(ORF4.GFP) in N. benthamiana. Thus the GRV MP, which shows limited sequence similarity to the CMV MP, was able to support CP-independent cell-to-cell movement of the hybrid Virus, but CP was still required for long-distance movement and entry of particular vascular cells required functions encoded by different proteins.
A F Murant - One of the best experts on this subject based on the ideXlab platform.
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Groundnut Rosette disease Virus complex biology and molecular biology
2000Co-Authors: Michael Taliansky, D J Robinson, A F MurantAbstract:Publisher Summary This chapter focuses on the cause of Rosette disease of Groundnut in which the umbraVirus Groundnut Rosette Virus (GRV) depends on Groundnut Rosette assistor Virus (GRAV) for transmission by Aphis craccivora . The GRV/GRAV complex is, especially interesting, because the main cause of Rosette disease symptoms in Groundnut is a third component, a satellite RNA, which depends on GRV for its replication but on GRAV for its encapsidation and transmission by aphids. There are two major symptom variants, chlorotic Rosette and green Rosette with considerable variation within each type. Both the chlorotic and green forms of the disease make plants severely stunted, with shortened internodes and reduced leaf size. In chlorotic Rosette, the leaves are bright yellow, usually with a few green islands. The biological properties of GRAV, which replicates autonomously in plants, are typical of a luteoVirus and GRAV is therefore classified within the family Luteoviridae .
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the satellite rnas associated with the Groundnut Rosette disease complex and pea enation mosaic Virus sequence similarities and ability of each other s helper Virus to support their replication
1996Co-Authors: S A Demler, Gustaaf A De Zoeten, D G Rucker, D J Robinson, Angelika Ziegler, A F MurantAbstract:Pea enation mosaic Virus (PEMV) and the causal agents of Groundnut Rosette disease are diverse examples of disease complexes involving two RNA species, one of which is related to the genomes of luteoViruses and the other to those of umbraViruses. In both complexes, these viral RNA components may be supplemented with satellite RNAs that are dependent on the umbraVirus component for replication and systemic movement, and on the luteoVirus component for encapsidation and vector transmission. Sequence analysis identified regions of similarity between the satellites of Groundnut Rosette Virus (GRV) and PEMV, particularly at the 5′ and 3′ termini and around duplicate sequence repeats present in each satellite RNA. The umbraVirus GRV and the umbraVirus-like PEMV RNA-2 were each able to support the replication and systemic spread of homologous and heterologous satellites. The presence of the PEMV satellite in infections with GRV had no effect on symptom expression in Nicotiana spp. or in Arachis hypogaea. Likewise, in Pisum sativum, the GRV satellite had no effect on the symptoms induced by PEMV. However, the intense yellow blotch symptoms induced in Nicotiana benthamiana by the YB3 GRV satellite in conjunction with GRV were also manifested when PEMV was the helper. Although PEMV RNA-1 was capable of supporting the encapsidation and aphid transmission of the GRV satellite, no evidence was obtained that the essential role of the GRV satellite in the aphid transmission of GRV could be supplied by the PEMV satellite. These data further strengthen the hypothesis of an evolutionary relationship between PEMV and the luteoVirus-umbraVirus complexes.
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detection of Groundnut Rosette umbraVirus infections with radioactive and non radioactive probes to its satellite rna
1995Co-Authors: V C Blok, D J Robinson, Angelika Ziegler, K Scott, D B Dangora, A F MurantAbstract:Summary A cloned cDNA copy of the satellite RNA of Groundnut Rosette Virus (GRV), labelled with either 32P or digoxigenin, was used as a probe to detect the satellite RNA in infected leaves. The test was successfully applied to N. benthamiana and to Groundnuts, infected with isolates of GRV from East and West Africa and with isolates which cause different types of symptom in Groundnuts, including one which is almost symptomless. Although the probe did not react with extracts from plants infected with GRV isolates from which the satellite RNA had been artificially eliminated, all naturally occurring GRV isolates contain the satellite RNA. The test therefore provides a reliable indicator of infection by GRV.
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sequences of 10 variants of the satellite like rna 3 of Groundnut Rosette Virus
1994Co-Authors: V C Blok, D J Robinson, Angelika Ziegler, A F MurantAbstract:Ten cDNA clones, representing the satellite-like RNA-3 associated with five different isolates of Groundnut Rosette Virus, were prepared and sequenced. The sequences are at least 87% identical, but differences associated both with symptom differences and with geographical origin were found. The sequences contain up to five potential open reading frames (ORFs), of which three are in the strand that is most abundant in infected plants and two are in the complementary strand. Only one of these ORFs is present in all 10 sequences. Neither the sequence of RNA-3 nor that of its potential translation products had significant similarities to sequences in the databases.
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a variant of the satellite rna of Groundnut Rosette Virus that induces brilliant yellow blotch mosaic symptoms in nicotiana benthamiana
1991Co-Authors: I K Kumar, A F Murant, D J RobinsonAbstract:SUMMARY Some Malawian cultures of Groundnut Rosette Virus (GRV) give rise to variants that, although still causing symptoms of the chlorotic type of Rosette in Groundnut, induce brilliant yellow blotch mosaic symptoms, instead of the usual veinal chlorosis and mild mottle, in Nicotiana benthamiana. One such isolate (YB) induced the formation in infected plants of a 0.9 kbp dsRNA having extensive sequence homology with molecules of similar size in other naturally occurring isolates of GRV. These dsRNA molecules were shown to be double-stranded forms of single-stranded satellite RNA molecules. Experiments in which the satellite was removed from and restored to isolate YB, or exchanged with those from other GRV isolates, showed that it carries the determinant for yellow blotch mosaic symptoms. Plants inoculated with the 0.9 kbp dsRNA (denatured or undenatured) developed yellow blotch mosaic even when the satellite-free GRV helper was not inoculated until 11 days later. The satellite RNA is therefore a very stable molecule. Prior infection of N. benthamiana with a GRV isolate containing a normal form of the satellite protected against expression of yellow blotch mosaic symptoms when the plants were later inoculated with isolate YB, whereas prior infection with satellite-free isolates did not. This provides a simple method of determining whether a GRV isolate has an associated satellite RNA. The YB satellite seems to be a newly recognised variant additional to those known to cause the chlorotic, green and other forms of Groundnut Rosette disease.
Eugene V Ryabov - One of the best experts on this subject based on the ideXlab platform.
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cajal bodies and the nucleolus are required for a plant Virus systemic infection
2007Co-Authors: Sang Hyon Kim, Eugene V Ryabov, N O Kalinina, Daria V Rakitina, Trudi Gillespie, Stuart A Macfarlane, Sophie Haupt, John W S BrownAbstract:The nucleolus and Cajal bodies (CBs) are prominent interacting subnuclear domains involved in a number of crucial aspects of cell function. Certain Viruses interact with these compartments but the functions of such interactions are largely uncharacterized. Here, we show that the ability of the Groundnut Rosette Virus open reading frame (ORF) 3 protein to move viral RNA long distances through the phloem strictly depends on its interaction with CBs and the nucleolus. The ORF3 protein targets and reorganizes CBs into multiple CB-like structures and then enters the nucleolus by causing fusion of these structures with the nucleolus. The nucleolar localization of the ORF3 protein is essential for subsequent formation of viral ribonucleoprotein (RNP) particles capable of Virus long-distance movement and systemic infection. We provide a model whereby the ORF3 protein utilizes trafficking pathways involving CBs to enter the nucleolus and, along with fibrillarin, exit the nucleus to form viral 'transport-competent' RNP particles in the cytoplasm.
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umbraVirus encoded movement protein induces tubule formation on the surface of protoplasts and binds rna incompletely and non cooperatively
2001Co-Authors: Kulpash M Nurkiyanova, Eugene V Ryabov, N O Kalinina, Yongchang Fan, Igor A Andreev, A G Fitzgerald, Peter Palukaitis, Michael TalianskyAbstract:Various functions of the cell-to-cell movement protein (MP) of Groundnut Rosette Virus (GRV) were analysed. The GRV ORF4-encoded protein was shown by immunofluorescence microscopy to generate tubular structures that protrude from the surface of the protoplast. The protein encoded by ORF4 was assessed also for RNA-binding properties. This protein was tagged at its C terminus with six histidine residues, produced in Escherichia coli using an expression vector and purified by affinity chromatography. Gel retardation analysis demonstrated that, in contrast to many other viral MPs, including the 3a MP of Cucumber mosaic Virus (CMV), the ORF4-encoded protein bound non-cooperatively to viral ssRNA and formed complexes of low protein:RNA ratios. Competition binding experiments showed that the ORF4-encoded protein bound to both ssRNA and ssDNA without sequence specificity, but did not bind to dsDNA. UV cross-linking and nitrocellulose membrane-retention assays confirmed that both the GRV and the CMV MPs formed complexes with ssRNA and that these complexes showed similar stability in NaCl. Probing the MP–RNA complexes by atomic force microscopy demonstrated that the ORF4-encoded protein bound RNA incompletely, leaving protein-free RNA segments of varying length, while the CMV 3a protein formed highly packed complexes. The significance of the two properties of limited RNA binding and tubule formation of the umbraviral MP is discussed.
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umbraVirus encoded proteins both stabilize heterologous viral rna and mediate its systemic movement in some plant species
2001Co-Authors: Eugene V Ryabov, D J Robinson, Michael TalianskyAbstract:The proteins encoded by open reading frame 3 (ORF3) of the umbraViruses pea enation mosaic Virus-2 and tobacco mottle Virus, like that of Groundnut Rosette Virus, mediated the movement of viral RNA through the phloem of infected Nicotiana benthamiana or N. clevelandii plants when they were expressed from chimeric tobacco mosaic Virus in place of the coat protein. However, these chimeras did not move systemically in N. tabacum. In lysates of N. benthamiana or N. tabacum protoplasts, the chimeric RNAs were more stable than was RNA of tobacco mosaic Virus lacking the coat protein gene. The chimeric Viruses also protected the latter in trans, suggesting that the ORF3 proteins can increase the stability of heterologous viral RNA. Umbraviral ORF3 proteins contain a conserved arginine-rich domain, and the possible roles of this motif in the functions of the proteins are discussed.
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umbraVirus gene expression helps potato leafroll Virus to invade mesophyll tissues and to be transmitted mechanically between plants
2001Co-Authors: Eugene V Ryabov, H. Barker, Gillian Fraser, M A Mayo, Michael TalianskyAbstract:Potato leafroll Virus (PLRV) was mechanically transmissible when inocula also contained the umbraVirus Pea enation mosaic Virus-2 (PEMV-2). In plants infected with PLRV and PEMV-2, PLRV accumulated in clusters of mesophyll cells in both inoculated and systemically infected leaves. No transmissions were obtained by coinoculation with Potato Virus Y, Potato Virus X (PVX), Tobacco mosaic Virus, or Cucumber mosaic Virus (CMV), although PLRV was transmissible from mixtures with CMV(ORF4) (a recombinant that contained the movement protein (MP) gene of the umbraVirus Groundnut Rosette Virus (GRV) in place of the CMV MP gene). In contrast, neither a recombinant PVX that expressed GRV MP nor a mutant of CMV(ORF4), in which the CMV 2b gene was untranslatable, was able to help PLRV transmission. Possibly both a cell-to-cell movement function and counterdefense mechanisms such as those that block posttranscriptional gene silencing are involved in movement of PLRV within plants and its mechanical transmission between plants.
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host specific cell to cell and long distance movements of cucumber mosaic Virus are facilitated by the movement protein of Groundnut Rosette Virus
1999Co-Authors: Eugene V Ryabov, Peter Palukaitis, I M Roberts, Michael TalianskyAbstract:The cucumoVirus, cucumber mosaic Virus (CMV), requires both the 3a movement protein (MP) and the capsid protein (CP) for cell-to-cell movement. Replacement of the MP of CMV with the MP of the umbraVirus, Groundnut Rosette Virus (GRV), which does not encode a CP, resulted in a hybrid Virus, CMV(ORF4), which could move cell to cell in Nicotiana tabacum and long distance in N. benthamiana. After replacement of the CMV CP in CMV(ORF4) with the gene encoding the green fluorescent protein (GFP), the hybrid Virus, CMV(ORF4.GFP), expressing both the GRV MP and the GFP, could move cell to cell but not systemically in either Nicotiana species. Immunoelectron microscopic analysis of cells infected by the hybrid Viruses showed different cellular barriers in the vasculature preventing long-distance movement of CMV(ORF4) in N. tabacum and CMV(ORF4.GFP) in N. benthamiana. Thus the GRV MP, which shows limited sequence similarity to the CMV MP, was able to support CP-independent cell-to-cell movement of the hybrid Virus, but CP was still required for long-distance movement and entry of particular vascular cells required functions encoded by different proteins.
Angelika Ziegler - One of the best experts on this subject based on the ideXlab platform.
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the satellite rnas associated with the Groundnut Rosette disease complex and pea enation mosaic Virus sequence similarities and ability of each other s helper Virus to support their replication
1996Co-Authors: S A Demler, Gustaaf A De Zoeten, D G Rucker, D J Robinson, Angelika Ziegler, A F MurantAbstract:Pea enation mosaic Virus (PEMV) and the causal agents of Groundnut Rosette disease are diverse examples of disease complexes involving two RNA species, one of which is related to the genomes of luteoViruses and the other to those of umbraViruses. In both complexes, these viral RNA components may be supplemented with satellite RNAs that are dependent on the umbraVirus component for replication and systemic movement, and on the luteoVirus component for encapsidation and vector transmission. Sequence analysis identified regions of similarity between the satellites of Groundnut Rosette Virus (GRV) and PEMV, particularly at the 5′ and 3′ termini and around duplicate sequence repeats present in each satellite RNA. The umbraVirus GRV and the umbraVirus-like PEMV RNA-2 were each able to support the replication and systemic spread of homologous and heterologous satellites. The presence of the PEMV satellite in infections with GRV had no effect on symptom expression in Nicotiana spp. or in Arachis hypogaea. Likewise, in Pisum sativum, the GRV satellite had no effect on the symptoms induced by PEMV. However, the intense yellow blotch symptoms induced in Nicotiana benthamiana by the YB3 GRV satellite in conjunction with GRV were also manifested when PEMV was the helper. Although PEMV RNA-1 was capable of supporting the encapsidation and aphid transmission of the GRV satellite, no evidence was obtained that the essential role of the GRV satellite in the aphid transmission of GRV could be supplied by the PEMV satellite. These data further strengthen the hypothesis of an evolutionary relationship between PEMV and the luteoVirus-umbraVirus complexes.
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detection of Groundnut Rosette umbraVirus infections with radioactive and non radioactive probes to its satellite rna
1995Co-Authors: V C Blok, D J Robinson, Angelika Ziegler, K Scott, D B Dangora, A F MurantAbstract:Summary A cloned cDNA copy of the satellite RNA of Groundnut Rosette Virus (GRV), labelled with either 32P or digoxigenin, was used as a probe to detect the satellite RNA in infected leaves. The test was successfully applied to N. benthamiana and to Groundnuts, infected with isolates of GRV from East and West Africa and with isolates which cause different types of symptom in Groundnuts, including one which is almost symptomless. Although the probe did not react with extracts from plants infected with GRV isolates from which the satellite RNA had been artificially eliminated, all naturally occurring GRV isolates contain the satellite RNA. The test therefore provides a reliable indicator of infection by GRV.
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sequences of 10 variants of the satellite like rna 3 of Groundnut Rosette Virus
1994Co-Authors: V C Blok, D J Robinson, Angelika Ziegler, A F MurantAbstract:Ten cDNA clones, representing the satellite-like RNA-3 associated with five different isolates of Groundnut Rosette Virus, were prepared and sequenced. The sequences are at least 87% identical, but differences associated both with symptom differences and with geographical origin were found. The sequences contain up to five potential open reading frames (ORFs), of which three are in the strand that is most abundant in infected plants and two are in the complementary strand. Only one of these ORFs is present in all 10 sequences. Neither the sequence of RNA-3 nor that of its potential translation products had significant similarities to sequences in the databases.
