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Donald L. Nuss - One of the best experts on this subject based on the ideXlab platform.
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enhanced Hypovirus transmission by engineered super donor strains of the chestnut blight fungus cryphonectria parasitica into a natural population of strains exhibiting diverse vegetative compatibility genotypes
Virology, 2019Co-Authors: Cameron M Stauder, Donald L. Nuss, Dongxiu Zhang, M L Double, W L Macdonald, Amy M Metheny, Matthew T KassonAbstract:Abstract Horizontal transmission of virulence attenuating Hypoviruses of Cryphonectria parasitica is restricted by an allorecognition system termed vegetative incompatibility (vic). A super donor formulation of two engineered C. parasitica strains (SD328/SD82) with gene disruptions at four of six vic loci transmitted Hypovirus to strains in the laboratory independent of vic genotype. We now report the transmission of Hypovirus by the SD328/82 formulation to a diverse, natural C. parasitica population infecting American chestnut in a forest setting. Hypovirulent (HV) isolates were recovered from 94% of cankers treated with the Hypovirus-infected SD328/82 formulation compared to 51% of cankers treated with a Hypovirus-infected EU5/6 formulation (strains having the same vic genotypes as SD strains but lacking vic gene disruptions). Overall, the SD328/82 formulation transmitted Hypovirus into more divergent vic genotypes compared to the EU5/6 formulation. These results demonstrate the SD328/82 formulation can serve as an enhanced Hypovirus vector for highly divergent C. parasitica populations.
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enhanced Hypovirus transmission by engineered super donor strains of the chestnut blight fungus cryphonectria parasitica into a natural population of strains exhibiting diverse vegetative compatibility genotypes
Virology, 2019Co-Authors: Cameron M Stauder, Donald L. Nuss, Dongxiu Zhang, M L Double, W L Macdonald, Amy M Metheny, Matthew T KassonAbstract:Abstract Horizontal transmission of virulence attenuating Hypoviruses of Cryphonectria parasitica is restricted by an allorecognition system termed vegetative incompatibility (vic). A super donor formulation of two engineered C. parasitica strains (SD328/SD82) with gene disruptions at four of six vic loci transmitted Hypovirus to strains in the laboratory independent of vic genotype. We now report the transmission of Hypovirus by the SD328/82 formulation to a diverse, natural C. parasitica population infecting American chestnut in a forest setting. Hypovirulent (HV) isolates were recovered from 94% of cankers treated with the Hypovirus-infected SD328/82 formulation compared to 51% of cankers treated with a Hypovirus-infected EU5/6 formulation (strains having the same vic genotypes as SD strains but lacking vic gene disruptions). Overall, the SD328/82 formulation transmitted Hypovirus into more divergent vic genotypes compared to the EU5/6 formulation. These results demonstrate the SD328/82 formulation can serve as an enhanced Hypovirus vector for highly divergent C. parasitica populations.
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long term field study of transgenic hypovirulent strains of cryphonectria parasitica in a forest setting
Forest Pathology, 2017Co-Authors: M L Double, Donald L. Nuss, Matthew T Kasson, W R Rittenour, I Holaskova, D P G Short, W L MacdonaldAbstract:Summary Transgenic hypovirulent strains of Cryphonectria parasitica, the chestnut blight fungus, engineered to contain a chromosomally integrated full-length infectious cDNA copy of virulence-attenuating Hypoviruses, differ from natural hypovirulent strains in the ability to transmit Hypoviruses to ascospore progeny and with 100% efficiency through asexual spores. We report the results of a long-term field study that examined whether these properties result in enhanced hypovirulence establishment, dissemination and persistence under field conditions. Informed by previous field results using a severe Hypovirus, this study that employed 144 American chestnut trees was designed to provide improved inoculum formulation and delivery and to include the use of a mild Hypovirus isolate (less debilitating) CHV-1/Euro7 in an attempt to increase dissemination. Isogenic transgenic hypovirulent (TG), non-transgenic cytoplasmic hypovirulent (CH) or virus-free virulent (V) treatment strains were applied to artificially initiated and natural C. parasitica cankers three times each year for 7 years. Reservoirs of treatment inoculum also were initiated and refreshed annually for the first 6 years of the study. Sampling of 111,000 individual ascospores from 4,500 perithecia confirmed Hypovirus-containing spermatia successfully transmitted TG Hypoviruses to ascospore progeny under field conditions. Surprisingly, TG ascospore progeny were recovered 3 years after the last annual application of treatment inoculum. Repeated sampling of over 440 cankers revealed dissemination of both CH and TG hypovirulent strains. However, no significance differences in establishment or dissemination were observed for the two hypovirulent strains. The results are discussed in terms of the contribution of ascospore progeny to infection, competition by endemic virulent C. parasitica, size of inoculated trees and the biological control potential of TG hypovirulent strains.
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Mutagenesis of the Catalytic and Cleavage Site Residues of the Hypovirus Papain-Like Proteases p29 and p48 Reveals Alternative Processing and Contributions to Optimal Viral RNA Accumulation
2016Co-Authors: Kenneth S Jensen, Donald L. NussAbstract:The positive-stranded RNA genome of the prototypic virulence-attenuating Hypovirus CHV-1/EP713 contains two open reading frames (ORF), each encoding an autocatalytic papain-like leader protease. Protease p29, derived from the N-terminal portion of ORF A, functions as a suppressor of RNA silencing, while protease p48, derived from the N-terminal portion of ORF B, is re-quired for viral RNA replication. The catalytic and cleavage site residues required for autoproteolytic processing have been func-tionally mapped in vitro for both proteases but not confirmed in the infected fungal host. We report here the mutagenesis of the CHV-1/EP713 infectious cDNA clone to define the requirements for p29 and p48 cleavage and the role of autoproteolysis in the context of Hypovirus replication. Mutation of the catalytic cysteine and histidine residues for either p29 or p48 was tolerated but reduced viral RNA accumulation to ca. 20 to 50 % of the wild-type level. Mutation of the p29 catalytic residues caused an accumu-lation of unprocessed ORF A product p69. Surprisingly, the release of p48 from the ORF B-encoded polyprotein was not pre-vented by mutation of the p48 catalytic and cleavage site residues and was independent of p29. The results show that, while dis-pensable for Hypovirus replication, the autocatalytic processing of the leader proteases p29 and p48 contributes to optimal virus RNA accumulation. The role of the predicted catalytic residues in autoproteolytic processing of p29 was confirmed in the in-fected host, while p48 was found to also undergo alternative processing independent of the encoded papain-like protease activi-ties
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mutagenesis of the catalytic and cleavage site residues of the Hypovirus papain like proteases p29 and p48 reveals alternative processing and contributions to optimal viral rna accumulation
Journal of Virology, 2014Co-Authors: Kenneth S Jensen, Donald L. NussAbstract:The positive-stranded RNA genome of the prototypic virulence-attenuating Hypovirus CHV-1/EP713 contains two open reading frames (ORF), each encoding an autocatalytic papain-like leader protease. Protease p29, derived from the N-terminal portion of ORF A, functions as a suppressor of RNA silencing, while protease p48, derived from the N-terminal portion of ORF B, is required for viral RNA replication. The catalytic and cleavage site residues required for autoproteolytic processing have been functionally mapped in vitro for both proteases but not confirmed in the infected fungal host. We report here the mutagenesis of the CHV-1/EP713 infectious cDNA clone to define the requirements for p29 and p48 cleavage and the role of autoproteolysis in the context of Hypovirus replication. Mutation of the catalytic cysteine and histidine residues for either p29 or p48 was tolerated but reduced viral RNA accumulation to ca. 20 to 50% of the wild-type level. Mutation of the p29 catalytic residues caused an accumulation of unprocessed ORF A product p69. Surprisingly, the release of p48 from the ORF B-encoded polyprotein was not prevented by mutation of the p48 catalytic and cleavage site residues and was independent of p29. The results show that, while dispensable for Hypovirus replication, the autocatalytic processing of the leader proteases p29 and p48 contributes to optimal virus RNA accumulation. The role of the predicted catalytic residues in autoproteolytic processing of p29 was confirmed in the infected host, while p48 was found to also undergo alternative processing independent of the encoded papain-like protease activities. Importance: Hypoviruses are positive-strand RNA mycoviruses that attenuate virulence of their pathogenic fungal hosts. The prototypic Hypovirus CHV-1/EP713, which infects the chestnut bight fungus Cryphonetria parasitica, encodes two papain-like autocatalytic leader proteases, p29 and p48, that also have important functions in suppressing the RNA silencing antiviral defense response and in viral RNA replication, respectively. The mutational analyses of the CHV-1/EP713 infectious cDNA clone, reported here, define the requirements for p29 and p48 cleavage and the functional importance of autoproteolysis in the context of Hypovirus replication and exposed an alternative p48 processing pathway independent of the encoded papain-like protease activities. These findings provide additional insights into Hypovirus gene expression, replication, and evolution and inform ongoing efforts to engineer Hypoviruses for interrogating and modulating fungal virulence.
Baoshan Chen - One of the best experts on this subject based on the ideXlab platform.
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Image_4_Comparative Methylome Analysis Reveals Perturbation of Host Epigenome in Chestnut Blight Fungus by a Hypovirus.JPEG
2018Co-Authors: Sisi Zhou, Xiaorui Shen, Zhiqiang Wang, Baoshan ChenAbstract:In eukaryotic genomes, DNA methylation is an important type of epigenetic modification that plays crucial roles in many biological processes. To investigate the impact of a Hypovirus infection on the methylome of Cryphonectria parasitica, the chestnut blight fungus, whole-genome bisulfite sequencing (WGBS) was employed to generate single-base resolution methylomes of the fungus with/without Hypovirus infection. The results showed that Hypovirus infection alters methylation in all three contexts (CG, CHG, and CHH), especially in gene promoters. A total of 600 differentially methylated regions (DMRs) were identified, of which 144 could be annotated to functional genes. RNA-seq analysis revealed that DNA methylation in promoter is negatively correlated with gene expression. Among DMRs, four genes were shown to be involved in conidiation, orange pigment production, and virulence. Taken together, our DNA methylomes analysis provide valuable insights into the understanding of the relationship between DNA methylation and Hypovirus infection, as well as phenotypic traits in C. parasitica.
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Table_1_Comparative Methylome Analysis Reveals Perturbation of Host Epigenome in Chestnut Blight Fungus by a Hypovirus.XLSX
2018Co-Authors: Sisi Zhou, Xiaorui Shen, Zhiqiang Wang, Baoshan ChenAbstract:In eukaryotic genomes, DNA methylation is an important type of epigenetic modification that plays crucial roles in many biological processes. To investigate the impact of a Hypovirus infection on the methylome of Cryphonectria parasitica, the chestnut blight fungus, whole-genome bisulfite sequencing (WGBS) was employed to generate single-base resolution methylomes of the fungus with/without Hypovirus infection. The results showed that Hypovirus infection alters methylation in all three contexts (CG, CHG, and CHH), especially in gene promoters. A total of 600 differentially methylated regions (DMRs) were identified, of which 144 could be annotated to functional genes. RNA-seq analysis revealed that DNA methylation in promoter is negatively correlated with gene expression. Among DMRs, four genes were shown to be involved in conidiation, orange pigment production, and virulence. Taken together, our DNA methylomes analysis provide valuable insights into the understanding of the relationship between DNA methylation and Hypovirus infection, as well as phenotypic traits in C. parasitica.
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Comparative Methylome Analysis Reveals Perturbation of Host Epigenome in Chestnut Blight Fungus by a Hypovirus
Frontiers Media S.A., 2018Co-Authors: Sisi Zhou, Baoshan Chen, Xiaorui Shen, Zhiqiang WangAbstract:In eukaryotic genomes, DNA methylation is an important type of epigenetic modification that plays crucial roles in many biological processes. To investigate the impact of a Hypovirus infection on the methylome of Cryphonectria parasitica, the chestnut blight fungus, whole-genome bisulfite sequencing (WGBS) was employed to generate single-base resolution methylomes of the fungus with/without Hypovirus infection. The results showed that Hypovirus infection alters methylation in all three contexts (CG, CHG, and CHH), especially in gene promoters. A total of 600 differentially methylated regions (DMRs) were identified, of which 144 could be annotated to functional genes. RNA-seq analysis revealed that DNA methylation in promoter is negatively correlated with gene expression. Among DMRs, four genes were shown to be involved in conidiation, orange pigment production, and virulence. Taken together, our DNA methylomes analysis provide valuable insights into the understanding of the relationship between DNA methylation and Hypovirus infection, as well as phenotypic traits in C. parasitica
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Table_2_cpubi4 Is Essential for Development and Virulence in Chestnut Blight Fungus.XLSX
2018Co-Authors: Qi Chen, Jinzi Wang, Baoshan ChenAbstract:Ubiquitination plays key roles in eukaryotic growth, stress adaptation, and metabolic regulation. In our previous work, ubiquitin was found to be secreted in the Hypovirus-infected strain of Cryphonectria parasitica, a phytopathogenic filamentous fungus responsible for the chestnut blight. Here we report the functional and molecular characterization of a polyubiquitin gene, cpubi4, in C. parasitica. The expression of cpubi4 was upregulated by the infection of a Hypovirus. Deletion of cpubi4 resulted in abnormal morphology, reduced sporulation, attenuation of virulence, and significant reduction in ubiquitination. A total of 378 sites in 236 proteins were identified to be significantly decreased in ubiquitination in the absence of cpubi4. Quantitative proteome analysis revealed that 285 in 4,776 identified proteins changed in abundance (1.5-fold, P < 0.05) in the cpubi4 null mutant, as compared with the wild-type strain.
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Data_Sheet_1_cpubi4 Is Essential for Development and Virulence in Chestnut Blight Fungus.DOCX
2018Co-Authors: Qi Chen, Jinzi Wang, Baoshan ChenAbstract:Ubiquitination plays key roles in eukaryotic growth, stress adaptation, and metabolic regulation. In our previous work, ubiquitin was found to be secreted in the Hypovirus-infected strain of Cryphonectria parasitica, a phytopathogenic filamentous fungus responsible for the chestnut blight. Here we report the functional and molecular characterization of a polyubiquitin gene, cpubi4, in C. parasitica. The expression of cpubi4 was upregulated by the infection of a Hypovirus. Deletion of cpubi4 resulted in abnormal morphology, reduced sporulation, attenuation of virulence, and significant reduction in ubiquitination. A total of 378 sites in 236 proteins were identified to be significantly decreased in ubiquitination in the absence of cpubi4. Quantitative proteome analysis revealed that 285 in 4,776 identified proteins changed in abundance (1.5-fold, P < 0.05) in the cpubi4 null mutant, as compared with the wild-type strain.
Leslie L. Domier - One of the best experts on this subject based on the ideXlab platform.
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Transcriptional and Small RNA Responses of the White Mold Fungus Sclerotinia sclerotiorum to Infection by a Virulence-Attenuating Hypovirus.
Viruses, 2018Co-Authors: Shin-yi Lee Marzano, Achal Neupane, Leslie L. DomierAbstract:Mycoviruses belonging to the family Hypoviridae cause persistent infection of many different host fungi. We previously determined that the white mold fungus, Sclerotiniasclerotiorum, infected with Sclerotinia sclerotiorum Hypovirus 2-L (SsHV2-L) exhibits reduced virulence, delayed/reduced sclerotial formation, and enhanced production of aerial mycelia. To gain better insight into the cellular basis for these changes, we characterized changes in mRNA and small RNA (sRNA) accumulation in S.sclerotiorum to infection by SsHV2-L. A total of 958 mRNAs and 835 sRNA-producing loci were altered after infection by SsHV2-L, among which >100 mRNAs were predicted to encode proteins involved in the metabolism and trafficking of carbohydrates and lipids. Both S. sclerotiorum endogenous and virus-derived sRNAs were predominantly 22 nt in length suggesting one dicer-like enzyme cleaves both. Novel classes of endogenous small RNAs were predicted, including phasiRNAs and tRNA-derived small RNAs. Moreover, S. sclerotiorum phasiRNAs, which were derived from noncoding RNAs and have the potential to regulate mRNA abundance in trans, showed differential accumulation due to virus infection. tRNA fragments did not accumulate differentially after Hypovirus infection. Hence, in-depth analysis showed that infection of S. sclerotiorum by a hypovirulence-inducing Hypovirus produced selective, large-scale reprogramming of mRNA and sRNA production.
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Transfection of Sclerotinia sclerotiorum with In Vitro Transcripts of a Naturally Occurring Interspecific Recombinant of Sclerotinia sclerotiorum Hypovirus 2 Significantly Reduces Virulence of the Fungus
Journal of virology, 2015Co-Authors: Shin-yi Lee Marzano, Houston A. Hobbs, Berlin D. Nelson, Glen L. Hartman, Darin M. Eastburn, Nancy K. Mccoppin, Leslie L. DomierAbstract:ABSTRACT A recombinant strain of Sclerotinia sclerotiorum Hypovirus 2 (SsHV2) was identified from a North American Sclerotinia sclerotiorum isolate (328) from lettuce (Lactuca sativa L.) by high-throughput sequencing of total RNA. The 5′- and 3′-terminal regions of the genome were determined by rapid amplification of cDNA ends. The assembled nucleotide sequence was up to 92% identical to two recently reported SsHV2 strains but contained a deletion near its 5′ terminus of more than 1.2 kb relative to the other SsHV2 strains and an insertion of 524 nucleotides (nt) that was distantly related to Valsa ceratosperma Hypovirus 1. This suggests that the new isolate is a heterologous recombinant of SsHV2 with a yet-uncharacterized Hypovirus. We named the new strain Sclerotinia sclerotiorum Hypovirus 2 Lactuca (SsHV2L) and deposited the sequence in GenBank with accession number KF898354. Sclerotinia sclerotiorum isolate 328 was coinfected with a strain of Sclerotinia sclerotiorum endornavirus 1 and was debilitated compared to cultures of the same isolate that had been cured of virus infection by cycloheximide treatment and hyphal tipping. To determine whether SsHV2L alone could induce hypovirulence in S. sclerotiorum, a full-length cDNA of the 14,538-nt viral genome was cloned. Transcripts corresponding to the viral RNA were synthesized in vitro and transfected into a virus-free isolate of S. sclerotiorum, DK3. Isolate DK3 transfected with SsHV2L was hypovirulent on soybean and lettuce and exhibited delayed maturation of sclerotia relative to virus-free DK3, completing Koch9s postulates for the association of hypovirulence with SsHV2L. IMPORTANCE A cosmopolitan fungus, Sclerotinia sclerotiorum infects more than 400 plant species and causes a plant disease known as white mold that produces significant yield losses in major crops annually. Mycoviruses have been used successfully to reduce losses caused by fungal plant pathogens, but definitive relationships between Hypovirus infections and hypovirulence in S. sclerotiorum were lacking. By establishing a cause-and-effect relationship between Sclerotinia sclerotiorum Hypovirus Lactuca (SsHV2L) infection and the reduction in host virulence, we showed direct evidence that Hypoviruses have the potential to reduce the severity of white mold disease. In addition to intraspecific recombination, this study showed that recent interspecific recombination is an important factor shaping viral genomes. The construction of an infectious clone of SsHV2L allows future exploration of the interactions between SsHV2L and S. sclerotiorum, a widespread fungal pathogen of plants.
W L Macdonald - One of the best experts on this subject based on the ideXlab platform.
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enhanced Hypovirus transmission by engineered super donor strains of the chestnut blight fungus cryphonectria parasitica into a natural population of strains exhibiting diverse vegetative compatibility genotypes
Virology, 2019Co-Authors: Cameron M Stauder, Donald L. Nuss, Dongxiu Zhang, M L Double, W L Macdonald, Amy M Metheny, Matthew T KassonAbstract:Abstract Horizontal transmission of virulence attenuating Hypoviruses of Cryphonectria parasitica is restricted by an allorecognition system termed vegetative incompatibility (vic). A super donor formulation of two engineered C. parasitica strains (SD328/SD82) with gene disruptions at four of six vic loci transmitted Hypovirus to strains in the laboratory independent of vic genotype. We now report the transmission of Hypovirus by the SD328/82 formulation to a diverse, natural C. parasitica population infecting American chestnut in a forest setting. Hypovirulent (HV) isolates were recovered from 94% of cankers treated with the Hypovirus-infected SD328/82 formulation compared to 51% of cankers treated with a Hypovirus-infected EU5/6 formulation (strains having the same vic genotypes as SD strains but lacking vic gene disruptions). Overall, the SD328/82 formulation transmitted Hypovirus into more divergent vic genotypes compared to the EU5/6 formulation. These results demonstrate the SD328/82 formulation can serve as an enhanced Hypovirus vector for highly divergent C. parasitica populations.
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enhanced Hypovirus transmission by engineered super donor strains of the chestnut blight fungus cryphonectria parasitica into a natural population of strains exhibiting diverse vegetative compatibility genotypes
Virology, 2019Co-Authors: Cameron M Stauder, Donald L. Nuss, Dongxiu Zhang, M L Double, W L Macdonald, Amy M Metheny, Matthew T KassonAbstract:Abstract Horizontal transmission of virulence attenuating Hypoviruses of Cryphonectria parasitica is restricted by an allorecognition system termed vegetative incompatibility (vic). A super donor formulation of two engineered C. parasitica strains (SD328/SD82) with gene disruptions at four of six vic loci transmitted Hypovirus to strains in the laboratory independent of vic genotype. We now report the transmission of Hypovirus by the SD328/82 formulation to a diverse, natural C. parasitica population infecting American chestnut in a forest setting. Hypovirulent (HV) isolates were recovered from 94% of cankers treated with the Hypovirus-infected SD328/82 formulation compared to 51% of cankers treated with a Hypovirus-infected EU5/6 formulation (strains having the same vic genotypes as SD strains but lacking vic gene disruptions). Overall, the SD328/82 formulation transmitted Hypovirus into more divergent vic genotypes compared to the EU5/6 formulation. These results demonstrate the SD328/82 formulation can serve as an enhanced Hypovirus vector for highly divergent C. parasitica populations.
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evaluation of two decades of cryphonectria parasitica Hypovirus introduction in an american chestnut stand in wisconsin
Phytopathology, 2018Co-Authors: M L Double, Anita Davelos Baines, A. M. Jarosz, Dennis W Fulbright, W L MacdonaldAbstract:Hypovirus-infected Cryphonectria parasitica strains were introduced in a large stand of American chestnut (>4,000 individuals) in western Wisconsin (USA) to evaluate whether Hypoviruses can serve as biological control agents. They were deployed by treating cankers from 1992 to 1997 and again from 2004 to 2014. After 17 years of Hypovirus introductions within an area of the stand with the longest history of disease, isolation of Hypovirus-infected strains increased from 55% in 1994 to 86% in 2014 from cankers that were treated. During the same period, isolation from cankers that arose on trees with treated cankers increased from 29 to 72% and from 15 to 84% for cankers on nearby trees that received no treatment. Tree survivorship over the 23-year study period for trees with treated cankers was 51% compared with 31% for trees that were not treated. Introduction of Hypovirus has resulted in the regrowth of the crowns of many large-diameter trees. Putative recovery of American chestnut in this stand provides evidence that prolonged Hypovirus treatment can act as a biological control when limited numbers of vegetative compatibility types of C. parasitica exist.
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long term field study of transgenic hypovirulent strains of cryphonectria parasitica in a forest setting
Forest Pathology, 2017Co-Authors: M L Double, Donald L. Nuss, Matthew T Kasson, W R Rittenour, I Holaskova, D P G Short, W L MacdonaldAbstract:Summary Transgenic hypovirulent strains of Cryphonectria parasitica, the chestnut blight fungus, engineered to contain a chromosomally integrated full-length infectious cDNA copy of virulence-attenuating Hypoviruses, differ from natural hypovirulent strains in the ability to transmit Hypoviruses to ascospore progeny and with 100% efficiency through asexual spores. We report the results of a long-term field study that examined whether these properties result in enhanced hypovirulence establishment, dissemination and persistence under field conditions. Informed by previous field results using a severe Hypovirus, this study that employed 144 American chestnut trees was designed to provide improved inoculum formulation and delivery and to include the use of a mild Hypovirus isolate (less debilitating) CHV-1/Euro7 in an attempt to increase dissemination. Isogenic transgenic hypovirulent (TG), non-transgenic cytoplasmic hypovirulent (CH) or virus-free virulent (V) treatment strains were applied to artificially initiated and natural C. parasitica cankers three times each year for 7 years. Reservoirs of treatment inoculum also were initiated and refreshed annually for the first 6 years of the study. Sampling of 111,000 individual ascospores from 4,500 perithecia confirmed Hypovirus-containing spermatia successfully transmitted TG Hypoviruses to ascospore progeny under field conditions. Surprisingly, TG ascospore progeny were recovered 3 years after the last annual application of treatment inoculum. Repeated sampling of over 440 cankers revealed dissemination of both CH and TG hypovirulent strains. However, no significance differences in establishment or dissemination were observed for the two hypovirulent strains. The results are discussed in terms of the contribution of ascospore progeny to infection, competition by endemic virulent C. parasitica, size of inoculated trees and the biological control potential of TG hypovirulent strains.
Matthew T Kasson - One of the best experts on this subject based on the ideXlab platform.
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enhanced Hypovirus transmission by engineered super donor strains of the chestnut blight fungus cryphonectria parasitica into a natural population of strains exhibiting diverse vegetative compatibility genotypes
Virology, 2019Co-Authors: Cameron M Stauder, Donald L. Nuss, Dongxiu Zhang, M L Double, W L Macdonald, Amy M Metheny, Matthew T KassonAbstract:Abstract Horizontal transmission of virulence attenuating Hypoviruses of Cryphonectria parasitica is restricted by an allorecognition system termed vegetative incompatibility (vic). A super donor formulation of two engineered C. parasitica strains (SD328/SD82) with gene disruptions at four of six vic loci transmitted Hypovirus to strains in the laboratory independent of vic genotype. We now report the transmission of Hypovirus by the SD328/82 formulation to a diverse, natural C. parasitica population infecting American chestnut in a forest setting. Hypovirulent (HV) isolates were recovered from 94% of cankers treated with the Hypovirus-infected SD328/82 formulation compared to 51% of cankers treated with a Hypovirus-infected EU5/6 formulation (strains having the same vic genotypes as SD strains but lacking vic gene disruptions). Overall, the SD328/82 formulation transmitted Hypovirus into more divergent vic genotypes compared to the EU5/6 formulation. These results demonstrate the SD328/82 formulation can serve as an enhanced Hypovirus vector for highly divergent C. parasitica populations.
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enhanced Hypovirus transmission by engineered super donor strains of the chestnut blight fungus cryphonectria parasitica into a natural population of strains exhibiting diverse vegetative compatibility genotypes
Virology, 2019Co-Authors: Cameron M Stauder, Donald L. Nuss, Dongxiu Zhang, M L Double, W L Macdonald, Amy M Metheny, Matthew T KassonAbstract:Abstract Horizontal transmission of virulence attenuating Hypoviruses of Cryphonectria parasitica is restricted by an allorecognition system termed vegetative incompatibility (vic). A super donor formulation of two engineered C. parasitica strains (SD328/SD82) with gene disruptions at four of six vic loci transmitted Hypovirus to strains in the laboratory independent of vic genotype. We now report the transmission of Hypovirus by the SD328/82 formulation to a diverse, natural C. parasitica population infecting American chestnut in a forest setting. Hypovirulent (HV) isolates were recovered from 94% of cankers treated with the Hypovirus-infected SD328/82 formulation compared to 51% of cankers treated with a Hypovirus-infected EU5/6 formulation (strains having the same vic genotypes as SD strains but lacking vic gene disruptions). Overall, the SD328/82 formulation transmitted Hypovirus into more divergent vic genotypes compared to the EU5/6 formulation. These results demonstrate the SD328/82 formulation can serve as an enhanced Hypovirus vector for highly divergent C. parasitica populations.
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long term field study of transgenic hypovirulent strains of cryphonectria parasitica in a forest setting
Forest Pathology, 2017Co-Authors: M L Double, Donald L. Nuss, Matthew T Kasson, W R Rittenour, I Holaskova, D P G Short, W L MacdonaldAbstract:Summary Transgenic hypovirulent strains of Cryphonectria parasitica, the chestnut blight fungus, engineered to contain a chromosomally integrated full-length infectious cDNA copy of virulence-attenuating Hypoviruses, differ from natural hypovirulent strains in the ability to transmit Hypoviruses to ascospore progeny and with 100% efficiency through asexual spores. We report the results of a long-term field study that examined whether these properties result in enhanced hypovirulence establishment, dissemination and persistence under field conditions. Informed by previous field results using a severe Hypovirus, this study that employed 144 American chestnut trees was designed to provide improved inoculum formulation and delivery and to include the use of a mild Hypovirus isolate (less debilitating) CHV-1/Euro7 in an attempt to increase dissemination. Isogenic transgenic hypovirulent (TG), non-transgenic cytoplasmic hypovirulent (CH) or virus-free virulent (V) treatment strains were applied to artificially initiated and natural C. parasitica cankers three times each year for 7 years. Reservoirs of treatment inoculum also were initiated and refreshed annually for the first 6 years of the study. Sampling of 111,000 individual ascospores from 4,500 perithecia confirmed Hypovirus-containing spermatia successfully transmitted TG Hypoviruses to ascospore progeny under field conditions. Surprisingly, TG ascospore progeny were recovered 3 years after the last annual application of treatment inoculum. Repeated sampling of over 440 cankers revealed dissemination of both CH and TG hypovirulent strains. However, no significance differences in establishment or dissemination were observed for the two hypovirulent strains. The results are discussed in terms of the contribution of ascospore progeny to infection, competition by endemic virulent C. parasitica, size of inoculated trees and the biological control potential of TG hypovirulent strains.