The Experts below are selected from a list of 189 Experts worldwide ranked by ideXlab platform
Maria Ivone E Clara - One of the best experts on this subject based on the ideXlab platform.
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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.
Carla Varanda - One of the best experts on this subject based on the ideXlab platform.
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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.
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.
Piero Roggero - 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.
J. Vera-graziano - One of the best experts on this subject based on the ideXlab platform.
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First Report of Lettuce big-vein associated virus (Varicosavirus) Infecting Lettuce in Mexico.
Plant Disease, 2014Co-Authors: D. L. Ochoa-martínez, J. Alfonsina-hernández, J. Sánchez-escudero, D. Rodríguez-martínez, J. Vera-grazianoAbstract:Lettuce (Lactuca sativa) is a common consumed vegetable and a major source of income and nutrition for small farmers in Mexico. This crop is infected with at least nine viruses: Mirafiori lettuce big-vein virus (MiLBVV), Lettuce big-vein associated virus (LBVaV), both transmitted by the soil-borne fungus Olpidium brassicae; Tomato spotted wilt virus (TSWV), Tomato chlorotic spot virus (TCSV), Groundnut ringspot virus (GRSV), Lettuce mottle virus (LMoV), Cucumber mosaic virus (CMV), Bidens mosaic virus (BiMV), and Lettuce mosaic virus (LMV) (1). From March to May 2012, a disease on lettuce was observed in the south region of Mexico City displaying mild to severe mosaic, leaf deformation, reduced growth, slight thickening of the main vein, and plant death. At the beginning of the epidemic there were just a few plants with visible symptoms and 7 days later the entire crop was affected, causing a loss of 93% of the plants. It was estimated by counting the number of severely affected or dead plants in three pl...
