The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Bradley I. Hillman - One of the best experts on this subject based on the ideXlab platform.
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Phytophthora infestans RNA virus 2, a novel RNA virus from Phytophthora infestans, does not belong to any known virus group
Archives of Virology, 2019Co-Authors: Kevin Myers, Bradley I. HillmanAbstract:Phytophthora infestans is the causal agent of potato and tomato late blight. In this study, we obtained the complete genome sequence of a novel RNA virus from this plant pathogen, tentatively named “Phytophthora infestans RNA virus 2” (PiRV-2). The PiRV-2 genome is 11,170 nt in length and lacks a polyA tail. It contains a single large open reading frame (ORF) with short 5’ and 3’ untranslated regions. The ORF is predicted to encode a polyprotein of 3710 aa (calculated molecular weight, 410.94 kDa). This virus lacks significant similarity to any other known viruses, even in the conserved RNA-dependent RNA polymerase region. Phylogenetic analysis demonstrated that it did not cluster with any known virus group. We conclude that PiRV-2 belongs to a new virus family yet to be described. This virus was found to be faithfully transmitted through asexual reproduction.
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A member of the virus family Narnaviridae from the plant pathogenic oomycete Phytophthora infestans
Archives of Virology, 2012Co-Authors: Kevin Myers, Bradley I. HillmanAbstract:A virus that has properties consistent with inclusion in the virus family Narnaviridae was described in Phytophthora infestans , the oomycete that caused the Irish potato famine. The genome of Phytophthora infestans RNA virus 4 (PiRV-4) is 2,984 nt with short complementary terminal sequences and a single open reading frame predicted to encode an RNA-dependent RNA polymerase (RdRp) most closely related to saccharomyces cerevisiae narnavirus 20S (ScNV-20S) and ScNV-23S, the members of the genus Narnavirus , family Narnaviridae . This report constitutes the first description of a member of the family Narnaviridae from a host taxon outside of the kingdom Fungi.
Kevin Myers - One of the best experts on this subject based on the ideXlab platform.
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Phytophthora infestans RNA virus 2, a novel RNA virus from Phytophthora infestans, does not belong to any known virus group
Archives of Virology, 2019Co-Authors: Kevin Myers, Bradley I. HillmanAbstract:Phytophthora infestans is the causal agent of potato and tomato late blight. In this study, we obtained the complete genome sequence of a novel RNA virus from this plant pathogen, tentatively named “Phytophthora infestans RNA virus 2” (PiRV-2). The PiRV-2 genome is 11,170 nt in length and lacks a polyA tail. It contains a single large open reading frame (ORF) with short 5’ and 3’ untranslated regions. The ORF is predicted to encode a polyprotein of 3710 aa (calculated molecular weight, 410.94 kDa). This virus lacks significant similarity to any other known viruses, even in the conserved RNA-dependent RNA polymerase region. Phylogenetic analysis demonstrated that it did not cluster with any known virus group. We conclude that PiRV-2 belongs to a new virus family yet to be described. This virus was found to be faithfully transmitted through asexual reproduction.
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A member of the virus family Narnaviridae from the plant pathogenic oomycete Phytophthora infestans
Archives of Virology, 2012Co-Authors: Kevin Myers, Bradley I. HillmanAbstract:A virus that has properties consistent with inclusion in the virus family Narnaviridae was described in Phytophthora infestans , the oomycete that caused the Irish potato famine. The genome of Phytophthora infestans RNA virus 4 (PiRV-4) is 2,984 nt with short complementary terminal sequences and a single open reading frame predicted to encode an RNA-dependent RNA polymerase (RdRp) most closely related to saccharomyces cerevisiae narnavirus 20S (ScNV-20S) and ScNV-23S, the members of the genus Narnavirus , family Narnaviridae . This report constitutes the first description of a member of the family Narnaviridae from a host taxon outside of the kingdom Fungi.
Jonathan Yuen - One of the best experts on this subject based on the ideXlab platform.
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What is the evidence for sexual reproduction of Phytophthora infestans in Europe
Plant Pathology, 2012Co-Authors: Jonathan Yuen, Bjorn AnderssonAbstract:The biology of late blight of potato and tomato, caused by Phytophthora infestans, changed when sexual reproduction by the pathogen became possible in many parts of the world, including Europe. In northern Europe, especially Scandinavia, there is increasing evidence that the pathogen is reproducing sexually on a regular basis, although in other regions further south or to the west it appears to reproduce primarily in a clonal manner. The presence of both mating types, the production of viable oospores, and observations of fields with soilborne sources of inoculum are consistent with sexual reproduction. Studies with different marker systems have revealed a population structure without any dominating clonal lineages in Scandinavia, and that is most easily explained by sexual reproduction. Phytophthora infestans recovered from the soil can also be linked to parental genotypes using likelihood-based methods when codominant markers are used. A synthesis of all the available data points to a second centre of sexual reproduction in northern Europe.
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can weed hosts increase aggressiveness of Phytophthora infestans on potato
Phytopathology, 2012Co-Authors: Lina Gronberg, Bjorn Andersson, Jonathan YuenAbstract:Gronberg, L., Andersson, B., and Yuen, J. 2012. Can weed hosts increase aggressiveness of Phytophthora infestans on potato? Phytopathology 102:429-433. Potato late blight, caused by Phytophthora infestans, is a major disease in potato production throughout the world. In southern Sweden, hairy nightshade (Solanum physalifolium), an alternative non-crop host to the pathogen, is an increasing weed problem. Single-lesion leaves infected by P. infestans were collected from potato and hairy nightshade to determine phenotypic and genotypic population differentiation of P. infestans between the two hosts. Genotypic variation was estimated using microsatellites as markers. The results showed no genotypic differentiation in the samples between the two hosts. Aggressiveness tests were performed using the sampled isolates to cross-inoculate potato and hairy nightshade. The proportion of infected leaves, latency period, lesion growth rate, and sporulation capacity were measured. For isolates from hairy nightshade, the odds of infection were higher on both hosts combined. When tested on potato leaves, isolates from hairy nightshade showed a significantly shorter latency period and higher sporulation capacity compared with isolates from potato. This indicates that an alternative host can filter populations of P. infestans toward a higher aggressiveness, which could lead to increasing problems in controlling potato late blight.
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Modelling pathogen competition and displacement– Phytophthora infestans in Scandinavia
European Journal of Plant Pathology, 2012Co-Authors: Jonathan YuenAbstract:Populations of Phytophthora infestans have displaced less fit populations in a number of regions, but not in Scandinavia. In order to study this process, a simple epidemic model was developed, based on the Lotka-Volterra model for competition. The model contains two epidemics, each with logistic growth of two separate populations that interact with each other in that they compete for the same resource base (the plant). In Scandinavia, epidemics from suspected oospore infections are thought to start earlier than those originating from tubers, so routines were added to allow the epidemics to start at different time points. A numerical solution to the model was developed using the deSolve package of the open-source statistical program ‘R’. The resulting model allows examination of the relative importance of different values for the apparent infection rates and starting parameters for the two sub-epidemics. If epidemics from oospore infections start earlier than those from tuber infections, the delay for epidemic initiation via tuber infection would require extremely high values of r in order for this population to dominate at the end of the season. This could be one reason for the lack of persistent clones in the Scandinavian Phytophthora infestans population.
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estimating the level of susceptibility to Phytophthora infestans in potato genotypes
Phytopathology, 2009Co-Authors: Jonathan Yuen, Gregory A ForbesAbstract:Yuen, J. E., and Forbes, G. A. 2009. Estimating the level of susceptibility to Phytophthora infestans in potato genotypes. Phytopathology 99:782786. Resistance and susceptibility are closely related terms but differ in their underlying assumptions and measurement. Standardized methods for determining the level of resistance and susceptibility in potato to Phytophthora infestans, the causal agent of late blight, have traditionally been semiquantitative and are not based on a true interval scale, thus making their use in most mathematical and statistical operations inappropriate. Recently, researchers have attempted to develop interval scales using regression analysis of the direct or transformed area under the disease progress curve (AUDPC). In this article, a similar approach is described based on the relative AUDPC (RAUDPC) of one or two reference cultivars and tested using a data set of field trials involving cultivars with varying levels of susceptibility evaluated in different environments in several countries. The coefficient of variation (CV) among trials of the AUDPC was reduced when the RAUDPC was used and even more so when the RAUDPC was made relative to the RAUDPC of cv. Bintje (RaRAUDPC), which was present in all trials. The RaRAUDPC was used in regression models to estimate scale values for eight potato cultivars in 13 to 15 locations (depending on cultivar). The CVs of scale values measuring variation among sites were similar to those of the RaRAUDPC. Using two cultivars gave a slight improvement in CV, which was statistically significant. The scale developed here has ascending numbers for increasing susceptibility, is simple, and can be constructed as a ratio measure, which permitted the calculation of mean, variance, and CV.
Haiyun Wang - One of the best experts on this subject based on the ideXlab platform.
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the role of autophagy during development of the oomycete pathogen Phytophthora infestans
Journal of Genetics and Genomics, 2014Co-Authors: Fuxin Wang, Naiqin Zhong, Haiyun WangAbstract:Phytophthora infestans is a highly destructive plant pathogen that causes late blight disease in plants such as potato and tomato(Fry and Goodwin,1997).As a typical oomycete,the primary infective propagule of P.infestans is the sporangium,which can either germinate directly or release biflagellate zoospores that encyst and germinate on the host subsequently(Grenville-Briggs et al.,2005).Due to abundant formation of the sporangia and prolific sporulation,P.infestans can spread quickly in the host tissues and cause extensive necrosis of the infected plants(Kamoun and Smart,2005).
Bjorn Andersson - One of the best experts on this subject based on the ideXlab platform.
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What is the evidence for sexual reproduction of Phytophthora infestans in Europe
Plant Pathology, 2012Co-Authors: Jonathan Yuen, Bjorn AnderssonAbstract:The biology of late blight of potato and tomato, caused by Phytophthora infestans, changed when sexual reproduction by the pathogen became possible in many parts of the world, including Europe. In northern Europe, especially Scandinavia, there is increasing evidence that the pathogen is reproducing sexually on a regular basis, although in other regions further south or to the west it appears to reproduce primarily in a clonal manner. The presence of both mating types, the production of viable oospores, and observations of fields with soilborne sources of inoculum are consistent with sexual reproduction. Studies with different marker systems have revealed a population structure without any dominating clonal lineages in Scandinavia, and that is most easily explained by sexual reproduction. Phytophthora infestans recovered from the soil can also be linked to parental genotypes using likelihood-based methods when codominant markers are used. A synthesis of all the available data points to a second centre of sexual reproduction in northern Europe.
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can weed hosts increase aggressiveness of Phytophthora infestans on potato
Phytopathology, 2012Co-Authors: Lina Gronberg, Bjorn Andersson, Jonathan YuenAbstract:Gronberg, L., Andersson, B., and Yuen, J. 2012. Can weed hosts increase aggressiveness of Phytophthora infestans on potato? Phytopathology 102:429-433. Potato late blight, caused by Phytophthora infestans, is a major disease in potato production throughout the world. In southern Sweden, hairy nightshade (Solanum physalifolium), an alternative non-crop host to the pathogen, is an increasing weed problem. Single-lesion leaves infected by P. infestans were collected from potato and hairy nightshade to determine phenotypic and genotypic population differentiation of P. infestans between the two hosts. Genotypic variation was estimated using microsatellites as markers. The results showed no genotypic differentiation in the samples between the two hosts. Aggressiveness tests were performed using the sampled isolates to cross-inoculate potato and hairy nightshade. The proportion of infected leaves, latency period, lesion growth rate, and sporulation capacity were measured. For isolates from hairy nightshade, the odds of infection were higher on both hosts combined. When tested on potato leaves, isolates from hairy nightshade showed a significantly shorter latency period and higher sporulation capacity compared with isolates from potato. This indicates that an alternative host can filter populations of P. infestans toward a higher aggressiveness, which could lead to increasing problems in controlling potato late blight.