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Peter M. Waterhouse - One of the best experts on this subject based on the ideXlab platform.
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The Luteovirus P4 Movement Protein Is a Suppressor of Systemic RNA Silencing
Viruses, 2017Co-Authors: Adriana F. Fusaro, Régis L. Corrêa, Kenlee Nakasugi, Craig Jackson, Lawrence M. Kawchuk, Maite F. S. Vaslin, Deborah A. Barton, Melanie Kalischuk, Peter M. WaterhouseAbstract:The plant viral family Luteoviridae is divided into three genera: Luteovirus, Polerovirus and Enamovirus. Without assistance from another virus, members of the family are confined to the cells of the host plant’s vascular system. The first open reading frame (ORF) of poleroviruses and enamoviruses encodes P0 proteins which act as silencing suppressor proteins (VSRs) against the plant’s viral defense-mediating RNA silencing machinery. Luteoviruses, such as barley yellow dwarf virus-PAV (BYDV-PAV), however, have no P0 to carry out the VSR role, so we investigated whether other proteins or RNAs encoded by BYDV-PAV confer protection against the plant’s silencing machinery. Deep-sequencing of small RNAs from plants infected with BYDV-PAV revealed that the virus is subjected to RNA silencing in the phloem tissues and there was no evidence of protection afforded by a possible decoy effect of the highly abundant subgenomic RNA3. However, analysis of VSR activity among the BYDV-PAV ORFs revealed systemic silencing suppression by the P4 movement protein, and a similar, but weaker, activity by P6. The closely related BYDV-PAS P4, but not the polerovirus potato leafroll virus P4, also displayed systemic VSR activity. Both Luteovirus and the polerovirus P4 proteins also showed transient, weak local silencing suppression. This suggests that systemic silencing suppression is the principal mechanism by which the Luteoviruses BYDV-PAV and BYDV-PAS minimize the effects of the plant’s anti-viral defense.
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replicating satellite rna induces sequence specific dna methylation and truncated transcripts in plants
RNA, 2001Co-Authors: Mingbo Wang, Susan Wesley, E J Finnegan, Neil A Smith, Peter M. WaterhouseAbstract:Tobacco plants were transformed with a chimeric transgene comprising sequences encoding beta-glucuronidase (GUS) and the satellite RNA (satRNA) of cereal yellow dwarf Luteovirus. When transgenic plants were infected with potato leafroll Luteovirus (PLRV), which replicated the transgene-derived satRNA to a high level, the satellite sequence of the GUS:Sat transgene became densely methylated. Within the satellite region, all 86 cytosines in the upper strand and 73 of the 75 cytosines in the lower strand were either partially or fully methylated. In contrast, very low levels of DNA methylation were detected in the satellite sequence of the transgene in uninfected plants and in the flanking nonsatellite sequences in both infected and uninfected plants. Substantial amounts of truncated GUS:Sat RNA accumulated in the satRNA-replicating plants, and most of the molecules terminated at nucleotides within the first 60 bp of the satellite sequence. Whereas this RNA truncation was associated with high levels of satRNA replication, it appeared to be independent of the levels of DNA methylation in the satellite sequence, suggesting that it is not caused by methylation. All the sequenced GUS:Sat DNA molecules were hypermethylated in plants with replicating satRNA despite the phloem restriction of the helper PLRV. Also, small, sense and antisense approximately 22 nt RNAs, derived from the satRNA, were associated with the replicating satellite. These results suggest that the sequence-specific DNA methylation spread into cells in which no satRNA replication occurred and that this was mediated by the spread of unamplified satRNA and/or its associated 22 nt RNA molecules.
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replicating satellite rna induces sequence specific dna methylation and truncated transcripts in plants
Science & Engineering Faculty, 2001Co-Authors: Mingbo Wang, Susan Wesley, E J Finnegan, Neil A Smith, Peter M. WaterhouseAbstract:Tobacco plants were transformed with a chimeric transgene comprising sequences encoding β-glucuronidase (GUS) and the satellite RNA (satRNA) of cereal yellow dwarf Luteovirus. When transgenic plants were infected with potato leafroll Luteovirus (PLRV), which replicated the transgene-derived satRNA to a high level, the satellite sequence of the GUS:Sat transgene became densely methylated. Within the satellite region, all 86 cytosines in the upper strand and 73 of the 75 cytosines in the lower strand were either partially or fully methylated. In contrast, very low levels of DNA methylation were detected in the satellite sequence of the transgene in uninfected plants and in the flanking nonsatellite sequences in both infected and uninfected plants. Substantial amounts of truncated GUS:Sat RNA accumulated in the satRNA-replicating plants, and most of the molecules terminated at nucleotides within the first 60 bp of the satellite sequence. Whereas this RNA truncation was associated with high levels of satRNA replication, it appeared to be independent of the levels of DNA methylation in the satellite sequence, suggesting that it is not caused by methylation. All the sequenced GUS:Sat DNA molecules were hypermethylated in plants with replicating satRNA despite the phloem restriction of the helper PLRV. Also, small, sense and antisense ∼22 nt RNAs, derived from the satRNA, were associated with the replicating satellite. These results suggest that the sequence-specific DNA methylation spread into cells in which no satRNA replication occurred and that this was mediated by the spread of unamplified satRNA and/or its associated 22 nt RNA molecules.
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a single copy of a virus derived transgene encoding hairpin rna gives immunity to barley yellow dwarf virus
Molecular Plant Pathology, 2000Co-Authors: Mingbo Wang, David Abbott, Peter M. WaterhouseAbstract:Barley yellow dwarf virus-PAV (BYDV-PAV) is the most serious and widespread virus of cereals worldwide. Natural resistance genes against this Luteovirus give inadequate control, and previous attempts to introduce synthetic resistance into cereals have produced variable results. In an attempt to generate barley with protection against BYDV-PAV, plants were transformed with a transgene designed to produce hairpin (hp)RNA containing BYDV-PAV sequences. From 25 independent barley lines transformed with the BYDV-PAV hpRNA construct, nine lines showed extreme resistance to the virus and the majority of these contained a single transgene. In the progeny of two independent transgenic lines, inheritance of a single transgene consistently correlated with protection against BYDV-PAV. This protection was rated as immunity because the virus could not be detected in the challenged plants by ELISA nor recovered by aphid feeding experiments. In the field, BYDV-PAV is sometimes associated with the related Luteovirus Cereal yellow dwarf virus-RPV (CYDV-RPV). When the transgenic plants were challenged with BYDV-PAV and CYDV-RPV together, the plants were susceptible to CYDV-RPV but immune to BYDV-PAV. This shows that the immunity is virus-specific and not broken down by the presence of CYDV. It suggests that CYDV-RPV does not encode a silencing-suppressor gene or that its product does not protect BYDV-PAV against the plant's RNAi-like defence mechanism. Either way, our results indicate that the BYDV-PAV immunity will be robust in the field and is potentially useful in minimizing losses in cereal production worldwide.
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comparison of the coat protein movement protein and rna polymerase gene sequences of australian chinese and american isolates of barley yellow dwarf virus transmitted by rhopalosiphum padi
Archives of Virology, 1998Co-Authors: Mingbo Wang, Z Cheng, P Keese, Michael Graham, P J Larkin, Peter M. WaterhouseAbstract:Barley yellow dwarf Luteovirus-GPV (BYDV-GPV) is a common problem in Chinese wheat crops but is unrecorded elsewhere. A defining characteristic of GPV is its capacity to be transmitted efficiently by both Schizaphis graminum and Rhopaloshiphum padi. This dual aphid species transmission contrasts with those of BYDV-RPV and BYDV-SGV, globally distributed viruses, which are efficiently transmitted only by Rhopaloshiphum padi and Schizaphis graminum respectively. The viral RNA sequences encoding the coat protein (22K) gene, the movement protein (17K) gene, the region surrounding the conserved GDD motif of the polymerase gene and the intergenic sequences between these genes were determined for GPV and an Australian isolate of BYDV-RPV (RPVa). In all three genes, the sequences of GPV and RPVa were more similar to those of an American isolate of BYDV-RPV (RPVu) than to any other Luteovirus for which there is data available. RPVa and RPVu were very similar, especially their coat proteins which had 97% identity at the amino acid level. The coat protein of GPV had 76% and 78% amino acid identity with RPVa and RPVu respectively. The data suggest that RPVu and RPVa are correctly named as strains of the same serotype and that GPV is sufficiently different from either RPV strain to be considered a distinct BYDV type. The coat protein and movement protein genes of GPV are very dissimilar to SGV. The polymerase sequences of RPVu, RPVa and GPV show close affinities with those of the sobemo-like Luteoviruses and little similarity with those of the carmo-like Luteoviruses. The sequences of the coat proteins, movement proteins and the polymerase segments of BYDV serotypes, other than RPV and GPV, form a cluster that is separate from their counterpart sequences from dicot-infecting Luteoviruses. The RPV and GPV isolates consistently fall within a dicot-infecting cluster. This suggests that RPV and GPV evolved from within this group of viruses. Since these other viruses all infect dicots it seems likely that their common ancestor infected a dicot and that RPV and GPV evolved from a virus that switched hosts from a dicot to a monocot.
Allen W Miller - One of the best experts on this subject based on the ideXlab platform.
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Blackwell Science, LtdPathogen profile Barley yellow dwarf virus: Luteoviridae or Tombusviridae?
2014Co-Authors: Allen W Miller, S I Jun, Randy BeckettAbstract:Barley yellow dwarf virus (BYDV), the most economically important virus of small grains, features highly specialised relationships with its aphid vectors, a plethora of novel translation mechanisms mediated by long–distance RNA interactions, and an ambiguous taxonomic status. The structural and movement proteins of BYDV that confer aphid transmission and phloem-limitation properties resemble those of the Luteoviridae, the family in which BYDV is classified. In contrast, many genes and cis-acting signals involved in replication and gene expression most closely resemble those of the Tombusviridae. Taxonomy: BYDV is in genus Luteovirus, family Luteoviri-dae. BYDV includes at least two serotypes or viruses: BYDV-PAV and BYDV-MAV. The former BYDV-RPV is now Cereal yellow dwarf virus-RPV (CYDV-RPV). CYDV is in genus Polerovirus, fam-ily Luteoviridae. Genus Luteovirus shares many features with family Tombusviridae. Physical properties: ∼25 nm icosahedral (T = 3) virions. One major (22 kDa) and one minor (50–55 kDa) coat protein. 5.6–5.8 kb positive sense RNA genome with no 5′-cap and no poly(A) tail. Host range: Most grasses. Most important in oats, barley and wheat. Also infects maize and rice. Symptoms: Yellowing and dwarfing in barley, stunting in wheat; reddening, yellowing and blasting in oats. Some isolates cause leaf notching and curling. Key attractions: Model for the study of circulative trans-mission of aphid-transmitted viruses. Plethora of unusual trans-lation mechanisms. Evidence of recombination in recent evolutionary history creates taxonomic ambiguity. Economically important virus of wheat, barley and oats, worldwide. Useful websites/meetings: International symposium
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barley yellow dwarf virus luteoviridae or tombusviridae
Molecular Plant Pathology, 2002Co-Authors: Allen W Miller, Randy J BeckettAbstract:Summary Barley yellow dwarf virus (BYDV), the most economically important virus of small grains, features highly specialised relationships with its aphid vectors, a plethora of novel translation mechanisms mediated by long–distance RNA interactions, and an ambiguous taxonomic status. The structural and movement proteins of BYDV that confer aphid transmission and phloem-limitation properties resemble those of the Luteoviridae , the family in which BYDV is classified. In contrast, many genes and cis -acting signals involved in replication and gene expression most closely resemble those of the Tombusviridae . Taxonomy: BYDV is in genus Luteovirus, family Luteoviridae. BYDV includes at least two serotypes or viruses: BYDV-PAV and BYDV-MAV. The former BYDV-RPV is now Cereal yellow dwarf virus-RPV (CYDV-RPV). CYDV is in genus Polerovirus, family Luteoviridae. Genus Luteovirus shares many features with family Tombusviridae. Physical properties: ∼25 nm icosahedral (T = 3) virions. One major (22 kDa) and one minor (50–55 kDa) coat protein. 5.6–5.8 kb positive sense RNA genome with no 5′-cap and no poly(A) tail. Host range: Most grasses. Most important in oats, barley and wheat. Also infects maize and rice. Symptoms: Yellowing and dwarfing in barley, stunting in wheat; reddening, yellowing and blasting in oats. Some isolates cause leaf notching and curling. Key attractions: Model for the study of circulative transmission of aphid-transmitted viruses. Plethora of unusual translation mechanisms. Evidence of recombination in recent evolutionary history creates taxonomic ambiguity. Economically important virus of wheat, barley and oats, worldwide. Useful websites/meetings: International symposium: ‘Barley Yellow Dwarf Disease: Recent Advances and Future Strategies’, CIMMYT, El Batan, Mexico, 1–5 September 2002, http://www.cimmyt.cgiar.org/Research/wheat/Conf_BYD_02/invitation.htm http://www.cimmyt.org/Research/wheat/BYDVNEWS/htm/BYDVNEWS.htm Aphid transmission animation: http://www.ppws.vt.edu/~sforza/tmv/bydv_aph.html
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primary and secondary structural elements required for synthesis of barley yellow dwarf virus subgenomic rna1
Journal of Virology, 1999Co-Authors: Gennadiy Koev, B R Mohan, Allen W MillerAbstract:Barley yellow dwarf Luteovirus (BYDV) generates three 3′-coterminal subgenomic RNAs (sgRNAs) in infected cells. The promoter of sgRNA1 is a putative hot spot for RNA recombination in Luteovirus evolution. The sgRNA1 transcription start site was mapped previously to either nucleotide 2670 or nucleotide 2769 of BYDV genomic RNA (gRNA) in two independent studies. Our data support the former initiation site. The boundaries of the sgRNA1 promoter map between nucleotides 2595 and 2692 on genomic RNA. Computer prediction, phylogenetic comparison, and structural probing revealed two stem-loops (SL1 and SL2) in the sgRNA1 promoter region on the negative strand. Promoter function was analyzed by inoculating protoplasts with a full-length infectious clone of the BYDV genome containing mutations in the sgRNA promoter. Because the promoter is located in an essential coding region of the replicase gene, we duplicated it in a nonessential part of the genome from which a new sgRNA was expressed. Mutational analysis revealed that secondary structure, but not the nucleotide sequence, was important at the base of SL1. Regions with both RNA primary and secondary structural features that contributed to transcription initiation were found at the top of SL1. Primary sequence, but not the secondary structure, was required in SL2, which includes the initiation site. Disruption of base pairing near the sgRNA1 start site increased the level of transcription three- to fourfold. We propose that both primary and secondary structures of the sgRNA1 promoter of BYDV play unique roles in sgRNA1 promoter recognition and transcription initiation.
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barley yellow dwarf virus rna requires a cap independent translation sequence because it lacks a 5 cap
Virology, 1999Co-Authors: Edwards Allen, Shanping Wang, Allen W MillerAbstract:Abstract A 3′ translation enhancer (3′TE) sequence that facilitates cap-independent translation is located near the 3′ end of barley yellow dwarf Luteovirus RNA. Here, we show that the 3′TE is required for translation of the viral genome and thus for viral replication. Antisense inhibition showed that the 3′TE has significant secondary structure and is required for translation of virion RNA from infected plants and uncapped genomic transcripts but not for translation of capped transcripts. Direct end-labeling of RNAs verified the absence of a 5′ modification on virion RNA. Thus barley yellow dwarf virus differs from related viruses by having neither a genome-linked protein nor a 5′ cap.
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the satellite rna of barley yellow dwarf virus rpv is supported by beet western yellows virus in dicotyledonous protoplasts and plants
Virology, 1997Co-Authors: Lada Rasochova, Bryce W Falk, Boni K Passmore, Allen W MillerAbstract:The subgroup II Luteovirus barley yellow dwarf virus-RPV (BYDV-RPV) acts as a helper virus for a satellite RNA (satRPV RNA). The subgroup II Luteovirus beet western yellows virus (BWYV) and the ST9-associated RNA (ST9a RNA), a BWYVassociated RNA that encodes a polymerase similar to those of subgroup I Luteoviruses, were assayed for their ability to support replication of satRPV RNA. SatRPV RNA was replicated in tobacco protoplasts in the presence of BWYV RNA or a mixture of BWYV plus the ST9a RNA, but not in the presence of ST9a RNA alone. ST9a RNA stimulated BWYV RNA accumulation which, in turn, increased the accumulation of satRPV RNA. SatRPV RNA was encapsidated in BWYV capsids primarily as circular monomers, which differs from the linear monomers found in BYDV (RPV/ PAV) particles. SatRPV RNA was transmitted to Capsella bursa-pastoris plants by aphids only in the presence of BWYV and ST9a RNA. SatRPV RNA reduced accumulation of both BWYV helper and ST9a nonhelper RNAs in plants but did not affect symptoms. The replication of satRPV RNA only in the presence of subgroup II luteoviral RNAs but not in the presence of RNAs with subgroup I-like polymerase genes, in both monocotyledonous and dicotyledonous hosts, suggests that the specificity determinants of satRPV RNA replication are contained within the polymerase genes of supporting viruses rather than in structural genes or host plants. q 1997 Academic Press
G A De Zoeten - One of the best experts on this subject based on the ideXlab platform.
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expression and suppression of circulative aphid transmission in pea enation mosaic virus
Journal of General Virology, 1997Co-Authors: S A Demler, D G Ruckerfeeney, Jihad S Skaf, G A De ZoetenAbstract:Pea enation mosaic virus (PEMV) is composed of two autonomously replicating virus RNAs related to the genomic RNAs of viruses in the genera Luteovirus and Umbravirus. The transmission of PEMV resembles that of its Luteovirus relatives in utilizing circulative aphid transmission. However, unlike its Luteovirus counterparts, PEMV can also be mechanically transmitted. Prolonged mechanical passage of PEMV can lead to the loss of aphid transmissibility, a trait that is mirrored by specific changes in the PEMV virion composition. These changes were used to examine the virus contribution to vector transmission and the mechanisms by which it is regulated. Using a local lesion isolation technique, one aphid transmissible and two aphid non-transmissible isolates of PEMV were compared. Structural analysis of a 54 kDa minor structural subunit unique to the aphid transmissible isolate demonstrated that it was a fusion of the 21 kDa virus coat protein and a 33 kDa protein encoded immediately downstream of the 21 kDa ORF, consistent with the formation of the 54 kDa subunit by translational readthrough. Genetic analyses utilizing exchanges between infectious in vitro transcripts of each isolate demonstrated that although the 33 kDa protein was non-essential for infection, its presence was mandatory for aphid transmission, and that specific changes within the 33 kDa ORF were sufficient to confer or abolish aphid transmission. This study also demonstrates that isolates of PEMV exist as mixtures of aphid transmissible and non-transmissible genotypes, and provides insight into the mechanisms used by this virus to down-regulate aphid transmission in response to a specific selection pressure.
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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
Journal of General Virology, 1996Co-Authors: S A Demler, D G Rucker, G A De Zoeten, 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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replication of the satellite rna of pea enation mosaic virus is controlled by rna 2 encoded functions
Journal of General Virology, 1994Co-Authors: S A Demler, D G Rucker, L Nooruddin, G A De ZoetenAbstract:The helper virus mediating replication of the satellite RNA (RNA 3) of pea enation mosaic virus (PEMV) consists of two autonomously replicating, taxonomically unrelated viral RNAs with ties to the Luteovirus (RNA 1) and the newly proposed umbravirus (RNA 2) genera. The following study dissects the relative contribution of each of the genomic RNAs of PEMV to the subsistence and dissemination of this satellite RNA. Infectivity assays in a pea protoplast system demonstrate that RNA 2 alone is responsible for the replication of RNA 3, an observation that is supported in part by shared regions of sequence homology at the 5′ and 3′ termini of both RNAs. In pea seedlings, infectivity assays also demonstrated that the presence of RNA 2 alone is necessary for the systemic invasion of RNA 3. In contrast, the Luteovirus-like phase of PEMV (RNA 1) is solely responsible for the encapsidation and aphid transmission of both RNA 2 and the satellite RNA. In a manner comparable to several other virus-satellite systems, the satellite of PEMV also displays a differential response in its capacity to attenuate symptom expression in selected host species. Thus, the satellite RNA of PEMV exists in a trilateral arrangement with its host and two viral RNAs, comparable in many respects to the satellite-virus-host interaction occurring with ground-nut rosette disease.
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the chimeric nature of the genome of pea enation mosaic virus the independent replication of rna 2
Journal of General Virology, 1993Co-Authors: S A Demler, D G Rucker, G A De ZoetenAbstract:The genome of pea enation mosaic virus (PEMV) consists of two plus-sense RNAs, both of which are required for mechanical transmission. RNA 1 (5706 nucleotides) has strong sequence similarity with members of the Luteovirus group, a similarity with members of the Luteovirus group, a similarity that is also manifested in the symptomatology, cytopathology and vector transmission of this virus. RNA 2 (4253 nucleotides) is hypothesized to facilitate systemic invasion and mechanical transmission, attributes that distinguish PEMV from the phloem-limited Luteoviruses. Sequence analysis of RNA 2 has demonstrated that PEMV is unique among multicomponent viruses in that it lacks 3′- and 5′-terminal homology between its genomic RNAs. Sequence analysis of RNA 2 has identified an open reading frame encoding a putative product of 65K that contains a series of polymerase-like motifs typical of viral RNA-dependent RNA polymerases. This protein sequence lacks homology with the polymerase encoded on RNA 1 of PEMV, instead being more closely affiliated with the polymerases of viruses related to the carmo- and tombusvirus groups. Inoculation of pea protoplasts with RNA transcripts derived from a full-length cDNA clone of RNA 2 has demonstrated that RNA 2 replicates autonomously in the absence of RNA 1, although comparable inoculation of whole plants failed to establish a systemic infection. There is no evidence that RNA 2 encodes structural proteins, suggesting that encapsidation functions are supplied in trans by RNA 1, comparable to the helper-dependent complexes occurring within the Luteovirus group. These data suggest that the PEMV genome can be characterized as a symbiotic association of two taxonomically distinct viral RNAs cooperatively interacting in the establishment of a systemic virus infection.
F. E. Gildow - One of the best experts on this subject based on the ideXlab platform.
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genetic regulation of polerovirus and Luteovirus transmission in the aphid schizaphis graminum
Phytopathology, 2006Co-Authors: M E Burrows, Marie-cécile Caillaud, Dawn M Smith, E C Benson, F. E. Gildow, Stephen K GrayAbstract:Burrows, M. E., Caillaud, M. C., Smith, D. M., Benson, E. C., Gildow, F. E., and Gray, S. M. 2006. Genetic regulation of polerovirus and Luteovirus transmission in the aphid Schizaphis graminum. Phytopathology 96:828837. Sexual forms of two genotypes of the aphid Schizaphis graminum, one a vector, the other a nonvector of two viruses that cause barley yellow dwarf disease (Barley yellow dwarf virus [BYDV]-SGV, Luteovirus and Cereal yellow dwarf virus-RPV, polerovirus), were mated to generate F1 and F2 populations. Segregation of the transmission phenotype for both viruses in the F1 and F2 populations indicated that the transmission phenotype is under genetic control and that the parents are heterozygous for genes involved in transmission. The ability to transmit both viruses was correlated within the F1 and F2 populations, suggesting that a major gene or linked genes regulate the transmission. However, individual hybrid genotypes differed significantly in their ability to transmit each virus, indicating that in addition to a major gene, minor genes can affect the transmission of each virus independently. Gut and salivary gland associated transmission barriers were identified in the nonvector parent and some progeny, while other progeny possessed only a gut barrier or a salivary gland barrier. Hemolymph factors do not appear to be involved in determining the transmission phenotype. These results provide direct evidence that aphid transmission of Luteoviruses is genetically regulated in the insect and that the tissue-specific barriers to virus transmission are not genetically linked.
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Luteovirus aphid interactions
Annual Review of Phytopathology, 2003Co-Authors: Stewart M Gray, F. E. GildowAbstract:Members of the Luteoviridae are transmitted by aphids in a circulative, nonpropagative manner that requires the virus to be acquired through gut tissue into the aphid hemocoel and then exit through salivary tissues. This process is aphid species-specific and involves specific recognition of the virus by unidentified components on the membranes of gut and salivary tissues. Transport through the tissues is an endocytosis/exocytosis process. Both structural proteins of the virus are involved in the transmission process, with multiple protein domains regulating the movement and survival of the virus in the aphid and plant. Here we review what is known about the genetic, cellular, and molecular mechanisms regulating these complex and specific virus-aphid interactions.
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Identification, characterization, and relatedness of Luteovirus isolates from forage legumes.
Phytopathology, 1999Co-Authors: V. D. Damsteegt, A. L. Stone, Douglas G. Luster, F. E. Gildow, Anthony J Russo, O. P. SmithAbstract:ABSTRACT Virus isolates from forage legumes collected from eight different states were identified as Luteoviruses closely related to soybean dwarf Luteovirus dwarfing (SbDV-D) and yellowing (SbDV-Y) described in Japan. All isolates produced reddened leaf margins in subterranean clover and were transmitted in a persistent manner by Acrythosiphon pisum, but not by Aulacorthum solani. Specific monoclonal antibodies raised against SbDV-Y were differentially reactive with endemic isolates. Immunoblots probed with a SbDV-D polyclonal antiserum showed single 26-kDa coat protein bands, confirming close serological relatedness to SbDV. Analyses of genomic and subgenomic double-stranded RNAs and northern blot analyses confirmed genomic relatedness to SbDV. Based on our results, we conclude that the U.S. Luteovirus isolates studied comprise a strain or strains of the soybean dwarf virus that have clovers as common hosts and the pea aphid as a common vector.
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evidence for receptor mediated endocytosis regulating Luteovirus acquisition by aphids
Phytopathology, 1993Co-Authors: F. E. GildowAbstract:The ability of five cereal grain aphid species to acquire four vector-specific isolates of barley yellow dwarf Luteoviruses was tested. Aphids from New York clones of Rhopalosiphum maidis, R. padi, Schizaphis graminum, and Sitobion avenae acquired the New York type isolates of MAV, PAV, RMV, and RPV when fed on infected plants, regardless of the ability of each species to transmit the virus. Aphids from a California clone of Metopolophium dirhodum acquired MAV, PAV, and RMV, but not RPV []
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the aphid salivary gland basal lamina as a selective barrier associated with vector specific transmission of barley yellow dwarf Luteoviruses
Phytopathology, 1993Co-Authors: F. E. Gildow, S M GrayAbstract:The inability of virions of the MAV barley yellow dwarf Luteovirus to penetrate the extracellular basal lamina surrounding the accessory salivary glands of some nonvector aphid species suggests that the basal lamina may possess a selective function that regulates vector-specific Luteovirus transmission. When Sitobion avenae and Rhopalosiphum padi were fed for 2 wk of either MAV- or RPV-infected oats and then examined by electron microscopy, virions of both the transmitted MAV and the nontransmitted RPV were observed penetrating the salivary basal lamina of S. avenae [...]
S A Demler - One of the best experts on this subject based on the ideXlab platform.
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expression and suppression of circulative aphid transmission in pea enation mosaic virus
Journal of General Virology, 1997Co-Authors: S A Demler, D G Ruckerfeeney, Jihad S Skaf, G A De ZoetenAbstract:Pea enation mosaic virus (PEMV) is composed of two autonomously replicating virus RNAs related to the genomic RNAs of viruses in the genera Luteovirus and Umbravirus. The transmission of PEMV resembles that of its Luteovirus relatives in utilizing circulative aphid transmission. However, unlike its Luteovirus counterparts, PEMV can also be mechanically transmitted. Prolonged mechanical passage of PEMV can lead to the loss of aphid transmissibility, a trait that is mirrored by specific changes in the PEMV virion composition. These changes were used to examine the virus contribution to vector transmission and the mechanisms by which it is regulated. Using a local lesion isolation technique, one aphid transmissible and two aphid non-transmissible isolates of PEMV were compared. Structural analysis of a 54 kDa minor structural subunit unique to the aphid transmissible isolate demonstrated that it was a fusion of the 21 kDa virus coat protein and a 33 kDa protein encoded immediately downstream of the 21 kDa ORF, consistent with the formation of the 54 kDa subunit by translational readthrough. Genetic analyses utilizing exchanges between infectious in vitro transcripts of each isolate demonstrated that although the 33 kDa protein was non-essential for infection, its presence was mandatory for aphid transmission, and that specific changes within the 33 kDa ORF were sufficient to confer or abolish aphid transmission. This study also demonstrates that isolates of PEMV exist as mixtures of aphid transmissible and non-transmissible genotypes, and provides insight into the mechanisms used by this virus to down-regulate aphid transmission in response to a specific selection pressure.
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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
Journal of General Virology, 1996Co-Authors: S A Demler, D G Rucker, G A De Zoeten, 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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replication of the satellite rna of pea enation mosaic virus is controlled by rna 2 encoded functions
Journal of General Virology, 1994Co-Authors: S A Demler, D G Rucker, L Nooruddin, G A De ZoetenAbstract:The helper virus mediating replication of the satellite RNA (RNA 3) of pea enation mosaic virus (PEMV) consists of two autonomously replicating, taxonomically unrelated viral RNAs with ties to the Luteovirus (RNA 1) and the newly proposed umbravirus (RNA 2) genera. The following study dissects the relative contribution of each of the genomic RNAs of PEMV to the subsistence and dissemination of this satellite RNA. Infectivity assays in a pea protoplast system demonstrate that RNA 2 alone is responsible for the replication of RNA 3, an observation that is supported in part by shared regions of sequence homology at the 5′ and 3′ termini of both RNAs. In pea seedlings, infectivity assays also demonstrated that the presence of RNA 2 alone is necessary for the systemic invasion of RNA 3. In contrast, the Luteovirus-like phase of PEMV (RNA 1) is solely responsible for the encapsidation and aphid transmission of both RNA 2 and the satellite RNA. In a manner comparable to several other virus-satellite systems, the satellite of PEMV also displays a differential response in its capacity to attenuate symptom expression in selected host species. Thus, the satellite RNA of PEMV exists in a trilateral arrangement with its host and two viral RNAs, comparable in many respects to the satellite-virus-host interaction occurring with ground-nut rosette disease.
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the chimeric nature of the genome of pea enation mosaic virus the independent replication of rna 2
Journal of General Virology, 1993Co-Authors: S A Demler, D G Rucker, G A De ZoetenAbstract:The genome of pea enation mosaic virus (PEMV) consists of two plus-sense RNAs, both of which are required for mechanical transmission. RNA 1 (5706 nucleotides) has strong sequence similarity with members of the Luteovirus group, a similarity with members of the Luteovirus group, a similarity that is also manifested in the symptomatology, cytopathology and vector transmission of this virus. RNA 2 (4253 nucleotides) is hypothesized to facilitate systemic invasion and mechanical transmission, attributes that distinguish PEMV from the phloem-limited Luteoviruses. Sequence analysis of RNA 2 has demonstrated that PEMV is unique among multicomponent viruses in that it lacks 3′- and 5′-terminal homology between its genomic RNAs. Sequence analysis of RNA 2 has identified an open reading frame encoding a putative product of 65K that contains a series of polymerase-like motifs typical of viral RNA-dependent RNA polymerases. This protein sequence lacks homology with the polymerase encoded on RNA 1 of PEMV, instead being more closely affiliated with the polymerases of viruses related to the carmo- and tombusvirus groups. Inoculation of pea protoplasts with RNA transcripts derived from a full-length cDNA clone of RNA 2 has demonstrated that RNA 2 replicates autonomously in the absence of RNA 1, although comparable inoculation of whole plants failed to establish a systemic infection. There is no evidence that RNA 2 encodes structural proteins, suggesting that encapsidation functions are supplied in trans by RNA 1, comparable to the helper-dependent complexes occurring within the Luteovirus group. These data suggest that the PEMV genome can be characterized as a symbiotic association of two taxonomically distinct viral RNAs cooperatively interacting in the establishment of a systemic virus infection.
