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Maria Ivone E Clara - One of the best experts on this subject based on the ideXlab platform.
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olive mild mosaic virus transmission by Olpidium virulentus
European Journal of Plant Pathology, 2015Co-Authors: Carla Varanda, Maria Ivone E Clara, Susana Santos, Maria Do Rosario FelixAbstract:The ability of Olpidium virulentus to vector Olive latent virus 1 (OLV-1), Olive mild mosaic virus (OMMV) and Tobacco necrosis virus D (TNV-D) was evaluated. Transmission assays involved zoospore acquisition of each virus, inoculation onto cabbage plant roots followed by viral detection. Assays revealed that these viruses are transmitted in the absence of the fungus, but the transmission rates of OMMV are much higher when OMMV is incubated with O. virulentus zoospores prior to inoculation, while the transmission rates of each OLV-1 and TNV-D do not change when they are incubated with the fungus. Our data shows that O. virulentus is an efficient vector of OMMV, greatly enhancing virus transmissibility, but not that of OLV-1 nor TNV-D. Prior studies have shown that another fungus, O. brassicae, also enhances OMMV transmission. To our knowledge, this is the first report of a plant virus, OMMV, being efficiently transmitted by two different species of fungi.
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specific amino acids of olive mild mosaic virus coat protein are involved in transmission by Olpidium brassicae
Journal of General Virology, 2011Co-Authors: Carla Varanda, Maria Do Rosario Felix, Claudio M Soares, Solange Oliveira, Maria Ivone E ClaraAbstract:Transmission of Olive mild mosaic virus (OMMV) is facilitated by Olpidium brassicae (Wor.) Dang. An OMMV mutant (OMMVL11) containing two changes in the coat protein (CP), asparagine to tyrosine at position 189 and alanine to threonine at position 216, has been shown not to be Olpidium brassicae-transmissible owing to inefficient attachment of virions to zoospores. In this study, these amino acid changes were separately introduced into the OMMV genome through site-directed mutagenesis, and the asparagine-to-tyrosine change was shown to be largely responsible for the loss of transmission. Analysis of the structure of OMMV CP by comparative modelling approaches showed that this change is located in the interior of the virus particle and the alanine-to-threonine change is exposed on the surface. The asparagine-to-tyrosine change may indirectly affect attachment via changes in the conformation of viral CP subunits, altering the receptor binding site and thus preventing binding to the fungal zoospore.
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Evidence of olive mild mosaic virus transmission by Olpidium brassicae
European Journal of Plant Pathology, 2011Co-Authors: Carla Varanda, Marta S. M. R. Silva, Maria Do Rosário F. Félix, Maria Ivone E ClaraAbstract:Transmission of three strains of OMMV by an Olpidium sp. was evaluated and compared. The three strains were 1) an OMMV wild type (WT) recovered from olive trees, 2) an OMMV variant (L11) obtained after 15 serial passages of single local lesions induced in Chenopodium murale plants, and 3) a construct OMMV/OMMVL11 in which the coat protein (CP) gene replaced that of the wild type. A single-sporangial culture derived from Chinese cabbage ( Brassica pekinensis) used as a bait plant grown in soil of an olive orchard, was identified as Olpidium brassicae based on the size and sequence of the generated amplicon in PCR specific tests. Each of the three virus strains was soil transmitted to cabbage roots in the absence of the fungus at similar rates of 30 to 40%. Separate plant inoculation by O. brassicae zoospores incubated with each viral strain resulted in enhanced transmission of OMMV, reaching 86% of infection whereas that of the other two strains remained practically unaffected at ca . 34%. Binding assays showed that the amount of virus bound to zoospores, estimated spectrophotometrically, was 7% in the case of OMMV, and practically nil in the case of the other two viral strains. Substitution of the coat protein (CP) gene of OMMV by that of the OMMV L11 strain, drastically reduced viral transmissibility in the presence of zoospores to the level of that observed in their absence. Our data shows that OMMV soil transmission is greatly enhanced by O. brassicae zoospores and that the viral CP plays a significant role in this process, most likely by facilitating virus binding and later entrance into the host plant roots.
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short communication specific amino acids of olive mild mosaic virus coat protein are involved in transmission by Olpidium brassicae
2011Co-Authors: Carla Varanda, Solange Oliveira, Maria Ivone E ClaraAbstract:Departamento de Biologia, Universidade de E´vora, 7002-554 E´vora, PortugalTransmission of Olive mild mosaic virus (OMMV) is facilitated by Olpidium brassicae (Wor.)Dang. An OMMV mutant (OMMVL11) containing two changes in the coat protein (CP),asparagine to tyrosine at position 189 and alanine to threonine at position 216, has been shownnot to be Olpidium brassicae-transmissible owing to inefficient attachment of virions tozoospores. In this study, these amino acid changes were separately introduced into the OMMVgenome through site-directed mutagenesis, and the asparagine-to-tyrosine change was shown tobe largely responsible for the loss of transmission. Analysis of the structure of OMMV CP bycomparative modelling approaches showed that this change is located in the interior of the virusparticle and the alanine-to-threonine change is exposed on the surface. The asparagine-to-tyrosine change may indirectly affect attachment via changes in the conformation of viral CPsubunits, altering the receptor binding site and thus preventing binding to the fungal zoospore.
R N Campbell - One of the best experts on this subject based on the ideXlab platform.
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Fungal transmission of plant viruses.
Annual Review of Phytopathology, 1996Co-Authors: R N CampbellAbstract:▪ Abstract Thirty soilborne viruses or virus-like agents are transmitted by five species of fungal vectors. Ten polyhedral viruses, of which nine are in the family Tombusviridae, are acquired in the in vitro manner and do not occur within the resting spores of their vectors, Olpidium brassicae and O. bornovanus. Fungal vectors for other viruses in the family should be sought even though tombusviruses are reputed to be soil transmitted without a vector. Eighteen rod-shaped viruses belonging to the furo- and bymovirus groups and to an unclassified group are acquired in the in vivo manner and survive within the resting spores of their vector, O. brassicae, Polymyxa graminis, P. betae, and Spongospora subterranea. The viral coat protein has an essential role in in vitro transmission. With in vivo transmission a site in the coat protein-read through protein (CP-RT) of beet necrotic yellow vein furovirus determines vector transmissibility as does a site in a similar 98-kDa polyprotein of barley mild mosaic bymo...
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Lettuce ring necrosis, a viruslike disease of lettuce: evidence for transmission by Olpidium brassicae
Plant Disease, 1996Co-Authors: R N Campbell, Hervé LotAbstract:Lettuce ring necrosis (LRN) caused severe symptoms on butterhead and crisphead types of lettuce but only mild symptoms on iceberg or cos types Single sporangial isolates of Olpidium brassicae were prepared from three sites in France to prove the vector role of the fungus and lo attempt the separation of the LRN agent (LRNA) and lettuce big vein virus (LBVV). A vector role for O. brassicae was demonstrated, but few isolates transmitted either agent, apparently because they were lost during one to two generation transfers of the fungus. Isolates transmitted LRNA and LBVV together or LBVV alone, but there was no clear evidence for transmission of LRNA alone. The LRNA was carried within the resting spores of the vector. Isolates of O. brassicae from two fields in the Salinas Valley of California carried LBVV and LRNA. This is the first report of LRNA in North America.
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involvement of the cucumber necrosis virus coat protein in the specificity of fungus transmission by Olpidium bornovanus
Virology, 1994Co-Authors: Morven A Mclean, R N Campbell, Richard I Hamilton, D'ann RochonAbstract:Abstract Cucumber necrosis (CNV) and the cherry strain of tomato bushy stunt (TBSV-Ch) are tombusviruses which differ in transmissibility by the fungus Olpidium bornovanus (Sahtiyanci) Karling (= O. radicale Schwartz and Cook). Zoospores acquire and transmit CNV, but not TBSV-Ch, in the in vitro manner. To assess the robe of the coat protein in the specificity of fungus transmission, reciprocal exchanges were made between the coat protein genes of these two viruses in full-length infectious cDNA crones. Virions containing a modified TBSV-Ch genome with the CNV coat protein gene were efficiently transmitted, but those containing a modified CNV genome with the TBSV-Ch coat protein gene were not. This is the first direct demonstration for the role of a viral coat protein in the specificity of transmission by a fungus.
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host specificity and nomenclature of Olpidium bornovanus Olpidium radicale and comparisons to Olpidium brassicae
Botany, 1994Co-Authors: R N Campbell, S T SimAbstract:Olpidium radicale Schwartz & Cook fide Lange & Insunza does not encompass O. radicale Schwartz & Cook emended Cook 1935. Thus, the combination Olpidium bornovanus (Sahtiyanci) Karling is accepted. Single sporangial isolates of O. bornovanus and Olipidium brassicae were prepared from bulk cultures trapped on cucurbit hosts using soils or roots obtained from France, California, Canada, and Brazil. The O. bornovanus isolates comprised three host-specific strains (cucumber, melon, and squash) based on the host in which they multiplied abundantly. All strains reproduced moderately well in watermelon, slightly in mung bean, and not at all in lettuce, cauliflower, red clover, or timothy. Two of three O. brassicae isolates trapped on melon had host specificity similar to that of the melon strains of O. bornovanus and the third was plurivorous. The vegetative generation time of O. bornovanus was longer (5+ days) than that of O. brassicae (3+ days). The O. bornovanus isolates grew at temperatures of 18–30 °C, where...
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Transmission of cucumber leaf spot virus by Olpidium radicale
Journal of General Virology, 1991Co-Authors: R N Campbell, Hervé Lecoq, C. Wipf Scheibel, S T SimAbstract:The ability of zoospores of four cultures of Olpidium radicale and one of O. brassicae to transmit viruses acquired in vitro from dilute virus solutions was compared. Transmission was demonstrated by infectivity and serological assays of the roots of cucumber seedlings 6 days after inoculation. A bulk culture of O. radicale, from cucumber plant roots collected near Nantes, France, a single-sporangial culture derived from it, and a single-sporangial culture from melon plant roots collected near Woodland, California, U.S.A., transmitted cucumber leaf spot virus (CLSV) and the cucumber fruit streak strain of CLSV (CLSV-FS). A bulk culture of O. radicale from melon plant roots collected at Montfavet, France, did not transmit CLSV or CLSV-FS. All four cultures transmitted cucumber necrosis and melon necrotic spot viruses, used as positive controls, but they did not transmit cucumber soil-borne, squash necrosis, petunia asteroid mosaic or tobacco necrosis viruses. In each of the trials a single-sporangial culture of O. brassicae from lettuce plant grown in California transmitted only tobacco necrosis virus.
Carla Varanda - One of the best experts on this subject based on the ideXlab platform.
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olive mild mosaic virus transmission by Olpidium virulentus
European Journal of Plant Pathology, 2015Co-Authors: Carla Varanda, Maria Ivone E Clara, Susana Santos, Maria Do Rosario FelixAbstract:The ability of Olpidium virulentus to vector Olive latent virus 1 (OLV-1), Olive mild mosaic virus (OMMV) and Tobacco necrosis virus D (TNV-D) was evaluated. Transmission assays involved zoospore acquisition of each virus, inoculation onto cabbage plant roots followed by viral detection. Assays revealed that these viruses are transmitted in the absence of the fungus, but the transmission rates of OMMV are much higher when OMMV is incubated with O. virulentus zoospores prior to inoculation, while the transmission rates of each OLV-1 and TNV-D do not change when they are incubated with the fungus. Our data shows that O. virulentus is an efficient vector of OMMV, greatly enhancing virus transmissibility, but not that of OLV-1 nor TNV-D. Prior studies have shown that another fungus, O. brassicae, also enhances OMMV transmission. To our knowledge, this is the first report of a plant virus, OMMV, being efficiently transmitted by two different species of fungi.
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specific amino acids of olive mild mosaic virus coat protein are involved in transmission by Olpidium brassicae
Journal of General Virology, 2011Co-Authors: Carla Varanda, Maria Do Rosario Felix, Claudio M Soares, Solange Oliveira, Maria Ivone E ClaraAbstract:Transmission of Olive mild mosaic virus (OMMV) is facilitated by Olpidium brassicae (Wor.) Dang. An OMMV mutant (OMMVL11) containing two changes in the coat protein (CP), asparagine to tyrosine at position 189 and alanine to threonine at position 216, has been shown not to be Olpidium brassicae-transmissible owing to inefficient attachment of virions to zoospores. In this study, these amino acid changes were separately introduced into the OMMV genome through site-directed mutagenesis, and the asparagine-to-tyrosine change was shown to be largely responsible for the loss of transmission. Analysis of the structure of OMMV CP by comparative modelling approaches showed that this change is located in the interior of the virus particle and the alanine-to-threonine change is exposed on the surface. The asparagine-to-tyrosine change may indirectly affect attachment via changes in the conformation of viral CP subunits, altering the receptor binding site and thus preventing binding to the fungal zoospore.
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Evidence of olive mild mosaic virus transmission by Olpidium brassicae
European Journal of Plant Pathology, 2011Co-Authors: Carla Varanda, Marta S. M. R. Silva, Maria Do Rosário F. Félix, Maria Ivone E ClaraAbstract:Transmission of three strains of OMMV by an Olpidium sp. was evaluated and compared. The three strains were 1) an OMMV wild type (WT) recovered from olive trees, 2) an OMMV variant (L11) obtained after 15 serial passages of single local lesions induced in Chenopodium murale plants, and 3) a construct OMMV/OMMVL11 in which the coat protein (CP) gene replaced that of the wild type. A single-sporangial culture derived from Chinese cabbage ( Brassica pekinensis) used as a bait plant grown in soil of an olive orchard, was identified as Olpidium brassicae based on the size and sequence of the generated amplicon in PCR specific tests. Each of the three virus strains was soil transmitted to cabbage roots in the absence of the fungus at similar rates of 30 to 40%. Separate plant inoculation by O. brassicae zoospores incubated with each viral strain resulted in enhanced transmission of OMMV, reaching 86% of infection whereas that of the other two strains remained practically unaffected at ca . 34%. Binding assays showed that the amount of virus bound to zoospores, estimated spectrophotometrically, was 7% in the case of OMMV, and practically nil in the case of the other two viral strains. Substitution of the coat protein (CP) gene of OMMV by that of the OMMV L11 strain, drastically reduced viral transmissibility in the presence of zoospores to the level of that observed in their absence. Our data shows that OMMV soil transmission is greatly enhanced by O. brassicae zoospores and that the viral CP plays a significant role in this process, most likely by facilitating virus binding and later entrance into the host plant roots.
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short communication specific amino acids of olive mild mosaic virus coat protein are involved in transmission by Olpidium brassicae
2011Co-Authors: Carla Varanda, Solange Oliveira, Maria Ivone E ClaraAbstract:Departamento de Biologia, Universidade de E´vora, 7002-554 E´vora, PortugalTransmission of Olive mild mosaic virus (OMMV) is facilitated by Olpidium brassicae (Wor.)Dang. An OMMV mutant (OMMVL11) containing two changes in the coat protein (CP),asparagine to tyrosine at position 189 and alanine to threonine at position 216, has been shownnot to be Olpidium brassicae-transmissible owing to inefficient attachment of virions tozoospores. In this study, these amino acid changes were separately introduced into the OMMVgenome through site-directed mutagenesis, and the asparagine-to-tyrosine change was shown tobe largely responsible for the loss of transmission. Analysis of the structure of OMMV CP bycomparative modelling approaches showed that this change is located in the interior of the virusparticle and the alanine-to-threonine change is exposed on the surface. The asparagine-to-tyrosine change may indirectly affect attachment via changes in the conformation of viral CPsubunits, altering the receptor binding site and thus preventing binding to the fungal zoospore.
D'ann Rochon - One of the best experts on this subject based on the ideXlab platform.
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a multigene phylogeny of Olpidium and its implications for early fungal evolution
BMC Evolutionary Biology, 2011Co-Authors: D'ann Rochon, Satoshi Sekimoto, Jennifer E Long, Jaclyn Dee, Mary L BerbeeAbstract:From a common ancestor with animals, the earliest fungi inherited flagellated zoospores for dispersal in water. Terrestrial fungi lost all flagellated stages and reproduce instead with nonmotile spores. Olpidium virulentus (= Olpidium brassicae), a unicellular fungus parasitizing vascular plant root cells, seemed anomalous. Although Olpidium produces zoospores, in previous phylogenetic studies it appeared nested among the terrestrial fungi. Its position was based mainly on ribosomal gene sequences and was not strongly supported. Our goal in this study was to use amino acid sequences from four genes to reconstruct the branching order of the early-diverging fungi with particular emphasis on the position of Olpidium. We concatenated sequences from the Ef-2, RPB1, RPB2 and actin loci for maximum likelihood and Bayesian analyses. In the resulting trees, Olpidium virulentus, O. bornovanus and non-flagellated terrestrial fungi formed a strongly supported clade. Topology tests rejected monophyly of the Olpidium species with any other clades of flagellated fungi. Placing Olpidium at the base of terrestrial fungi was also rejected. Within the terrestrial fungi, Olpidium formed a monophyletic group with the taxa traditionally classified in the phylum Zygomycota. Within Zygomycota, Mucoromycotina was robustly monophyletic. Although without bootstrap support, Monoblepharidomycetes, a small class of zoosporic fungi, diverged from the basal node in Fungi. The zoosporic phylum Blastocladiomycota appeared as the sister group to the terrestrial fungi plus Olpidium. This study provides strong support for Olpidium as the closest living flagellated relative of the terrestrial fungi. Appearing nested among hyphal fungi, Olpidium's unicellular thallus may have been derived from ancestral hyphae. Early in their evolution, terrestrial hyphal fungi may have reproduced with zoospores.
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molecular aspects of plant virus transmission by Olpidium and plasmodiophorid vectors
Annual Review of Phytopathology, 2004Co-Authors: D'ann Rochon, Kishore Kakani, Marjorie Robbins, Ron ReadeAbstract:▪ Abstract The genome structures of a large number of viruses transmitted by Olpidium and plasmodiophorid vectors have been determined. The viruses are highly diverse, belonging to 12 genera in at least 4 families. Plasmodiophorids are now classified as protists rather than true fungi. This finding, along with the recognition of the great variety of viruses transmitted by Olpidium and plasmodiophorid vectors, will likely lead to an elaboration of the details of in vitro and in vivo transmission mechanisms. Recent progress in elucidating the interaction between Cucumber necrosis virus (CNV) and its zoospore vector suggests that specific sites on the capsid as well as on the zoospore are involved in transmission. Moreover, some features of CNV/zoospore attachment are similar to poliovirus/host cell interactions, suggesting evolutionary conservation of functional features of plant and animal virus capsids.
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involvement of the cucumber necrosis virus coat protein in the specificity of fungus transmission by Olpidium bornovanus
Virology, 1994Co-Authors: Morven A Mclean, R N Campbell, Richard I Hamilton, D'ann RochonAbstract:Abstract Cucumber necrosis (CNV) and the cherry strain of tomato bushy stunt (TBSV-Ch) are tombusviruses which differ in transmissibility by the fungus Olpidium bornovanus (Sahtiyanci) Karling (= O. radicale Schwartz and Cook). Zoospores acquire and transmit CNV, but not TBSV-Ch, in the in vitro manner. To assess the robe of the coat protein in the specificity of fungus transmission, reciprocal exchanges were made between the coat protein genes of these two viruses in full-length infectious cDNA crones. Virions containing a modified TBSV-Ch genome with the CNV coat protein gene were efficiently transmitted, but those containing a modified CNV genome with the TBSV-Ch coat protein gene were not. This is the first direct demonstration for the role of a viral coat protein in the specificity of transmission by a fungus.
Hervé Lot - One of the best experts on this subject based on the ideXlab platform.
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Transmission by Olpidium brassicae of Mirafiori lettuce virus and Lettuce big-vein virus, and Their Roles in Lettuce Big-Vein Etiology
Phytopathology®, 2002Co-Authors: Hervé Lot, Robert N. Campbell, Sylvie Souche, Robert G. Milne, Piero RoggeroAbstract:Lot, H., Campbell, R. N., Souche, S., Milne, R. G., and Roggero, P. 2002. Transmission by Olpidium brassicae of Mirafiori lettuce virus and Lettuce big-vein virus, and their roles in lettuce big-vein etiology. Phytopathology 92:288-293. Big-vein disease occurs on lettuce worldwide in temperate conditions; the causal agent has been presumed to be Lettuce big-vein virus (LBVV), genus Varicosavirus, vectored by the soilborne fungus Olpidium brassicae. Recently, the role of LBVV in the etiology of big-vein disease has been questioned because a second soilborne virus, Mirafiori lettuce virus (MiLV), genus Ophiovirus, has been found frequently in big-veinaffected lettuce. LBVV and MiLV, detectable and distinguishable by enzyme-linked immunosorbent assay using specific antisera, were tested for their ability to be transmitted from lettuce to lettuce by mechanical inoculation of sap extracts, or by zoospores of O. brassicae, and to cause big-vein disease. Both viruses were mechanically transmissible from lettuce to herbaceous hosts and to lettuce, but very erratically. LBVV was transmitted by O. brassicae but lettuce infected with only this virus never showed symptoms. MiLV was transmitted in the same manner, and lettuce infected with this virus alone consistently developed big-vein symptoms regardless of the presence or absence of LBVV. With repeated mechanical transmission, isolates of both viruses appeared to lose the ability to be vectored, and MiLV appeared to lose the ability to cause bigvein symptoms. The recovery of MiLV (Mendocino isolate, from California) from stored O. brassicae resting spores puts the earliest directly demonstrable existence of MiLV at 1990.
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Lettuce ring necrosis, a viruslike disease of lettuce: evidence for transmission by Olpidium brassicae
Plant Disease, 1996Co-Authors: R N Campbell, Hervé LotAbstract:Lettuce ring necrosis (LRN) caused severe symptoms on butterhead and crisphead types of lettuce but only mild symptoms on iceberg or cos types Single sporangial isolates of Olpidium brassicae were prepared from three sites in France to prove the vector role of the fungus and lo attempt the separation of the LRN agent (LRNA) and lettuce big vein virus (LBVV). A vector role for O. brassicae was demonstrated, but few isolates transmitted either agent, apparently because they were lost during one to two generation transfers of the fungus. Isolates transmitted LRNA and LBVV together or LBVV alone, but there was no clear evidence for transmission of LRNA alone. The LRNA was carried within the resting spores of the vector. Isolates of O. brassicae from two fields in the Salinas Valley of California carried LBVV and LRNA. This is the first report of LRNA in North America.
