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Said A Ghabrial - One of the best experts on this subject based on the ideXlab platform.
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Chrysoviruses (Chrysoviridae) - General Features and Chrysovirus-Related Viruses
Encyclopedia of Virology, 2021Co-Authors: Ioly Kotta-loizou, José R Castón, Robert H. A. Coutts, Hiromitsu Moriyama, Said A GhabrialAbstract:Abstract The family Chrysoviridae encompasses viruses with isometric particles, 35–40 nm in diameter, and multipartite double-stranded RNA genomes. The family was recently reorganized to accommodate two genera, AlphaChrysovirus and BetaChrysovirus, which infect fungi and are also associated with plants and insects. Chrysoviruses are transmitted intracellularly; both vertically from parent to offspring and horizontally from one isolate to another, and may cause hypovirulence in their fungal hosts.
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private correspondance
2016Co-Authors: Daohong Jiang, Said A GhabrialAbstract:Molecular cloning and complete nucleotide sequencing of Penicillium chrysogenum virus (PcV) dsRNAs indicated that PcV virions contained four dsRNA segments with sizes of 3562, 3200, 2976 and 2902 bp. Each dsRNA segment had unique sequences and contained a single large open reading frame (ORF). In vitro translation of transcripts derived from full-length cDNA clones of PcV dsRNAs yielded single products of sizes similar to those predicted from the deduced amino acid sequences of the individual ORFs. Sequence similarity searches revealed that dsRNA1 encodes a putative RNA-dependent RNA polymerase. In this study, it was determined that dsRNA2 encodes the major capsid protein and that p4, encoded by dsRNA4, is virion-associated as a minor component. All four dsRNAs of PcV, like the genomic segments of viruses with multipartite genomes, were found to have extended regions of highly conserved terminal sequences at both ends. In addition to the strictly conserved 59-terminal 10 nt, a second region consisting of reiteration of the sequence CAA was found immediately upstream of the AUG initiator codon. These (CAA)n repeats are reminiscent of the translational enhancer elements of tobamoviruses. The 39-terminal 14 nt were also strictly conserved. As PcV and related viruses with four dsRNA segments (genus Chrysovirus) have not been previously characterized at the molecular level, they were provisionally classified in the family Partitiviridae, comprising viruses with bipartite genomes. This study represents the first report on molecular characterization of a Chrysovirus and the results suggest the creation of a new family of mycoviruses with multipartite dsRNA genomes to accommodate PcV and related viruses
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Reprint of "The victorivirus Helminthosporium victoriae virus 190S is the primary cause of disease/hypovirulence in its natural host and a heterologous host".
Virus research, 2016Co-Authors: Wendy M Havens, Nobuhiro Suzuki, Said A GhabrialAbstract:A transmissible disease of the plant pathogenic fungus Helminthosporium victoriae, the causal agent of Victoria blight of oats, was reported more than 50 years ago. Diseased, but not normal, isolates, of H. victoriae contain two distinct viruses designated according to their sedimentation values as victorivirus Helminthosporium victoriae virus 190S (HvV190S) and Chrysovirus Helminthosporium victoriae 145S (HvV145S). Although a viral etiology of the disease was previously proposed, conclusive evidence was lacking. Here we present unequivocal evidence based on transfecting virus-free H. victoriae protoplasts with purified virus particles showing that HvV190S is essential for disease development. Furthermore, we show an expansion of the host range of HvV190S to include Cryphonectria parasitica and we also show similarity in a subset of phenotypic traits between HvV190S-infected RNA silencing deficient mutant (Δdcl-2) of C. parasitica and a strain of H. victoriae. In virulence assays on detached American chestnut branches and Red Delicious apple fruits, HvV190S-infected C. parasitica strain Δdcl-2 was markedly less virulent than wild type and virus-free Δdcl-2 C. parasitica strains. Furthermore, the hypovirulent HvV190S-infected C. parasitica Δdcl-2 strain exhibited strong antifungal activity in dual culture with the plant pathogenic fungus Sclerotinia sclerotiorum. No such inhibitory activity was observed in comparable dual cultures with wild type and virus-free Δdcl-2 C. parasitica strains. The discovery that infection with HvV190S induced a hypovirulent phenotype in a heterologous plant pathogenic host is very significant since it might be possible to convert other economically important plant pathogenic fungi to hypovirulence using HvV190S.
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the victorivirus helminthosporium victoriae virus 190s is the primary cause of disease hypovirulence in its natural host and a heterologous host
Virus Research, 2016Co-Authors: Wendy M Havens, Nobuhiro Suzuki, Said A GhabrialAbstract:A transmissible disease of the plant pathogenic fungus Helminthosporium victoriae, the causal agent of Victoria blight of oats, was reported more than 50 years ago. Diseased, but not normal, isolates, of H. victoriae contain two distinct viruses designated according to their sedimentation values as victorivirus Helminthosporium victoriae virus 190S (HvV190S) and Chrysovirus Helminthosporium victoriae 145S (HvV145S). Although a viral etiology of the disease was previously proposed, conclusive evidence was lacking. Here we present unequivocal evidence based on transfecting virus-free H. victoriae protoplasts with purified virus particles showing that HvV190S is essential for disease development. Furthermore, we show an expansion of the host range of HvV190S to include Cryphonectria parasitica and we also show similarity in a subset of phenotypic traits between HvV190S-infected RNA silencing deficient mutant (Δdcl-2) of C. parasitica and a strain of H. victoriae. In virulence assays on detached American chestnut branches and Red Delicious apple fruits, HvV190S-infected C. parasitica strain Δdcl-2 was markedly less virulent than wild type and virus-free Δdcl-2 C. parasitica strains. Furthermore, the hypovirulent HvV190S-infected C. parasitica Δdcl-2 strain exhibited strong antifungal activity in dual culture with the plant pathogenic fungus Sclerotinia sclerotiorum. No such inhibitory activity was observed in comparable dual cultures with wild type and virus-free Δdcl-2 C. parasitica strains. The discovery that infection with HvV190S induced a hypovirulent phenotype in a heterologous plant pathogenic host is very significant since it might be possible to convert other economically important plant pathogenic fungi to hypovirulence using HvV190S.
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The victorivirus Helminthosporium victoriae virus 190S is the primary cause of disease/hypovirulence in its natural host and a heterologous host.
Virus Research, 2015Co-Authors: Wendy M Havens, Nobuhiro Suzuki, Said A GhabrialAbstract:A transmissible disease of the plant pathogenic fungus Helminthosporium victoriae, the causal agent of Victoria blight of oats, was reported more than 50 years ago. Diseased, but not normal, isolates, of H. victoriae contain two distinct viruses designated according to their sedimentation values as victorivirus Helminthosporium victoriae virus 190S (HvV190S) and Chrysovirus Helminthosporium victoriae 145S (HvV145S). Although a viral etiology of the disease was previously proposed, conclusive evidence was lacking. Here we present unequivocal evidence based on transfecting virus-free H. victoriae protoplasts with purified virus particles showing that HvV190S is essential for disease development. Furthermore, we show an expansion of the host range of HvV190S to include Cryphonectria parasitica and we also show similarity in a subset of phenotypic traits between HvV190S-infected RNA silencing deficient mutant (Δdcl-2) of C. parasitica and a strain of H. victoriae. In virulence assays on detached American chestnut branches and Red Delicious apple fruits, HvV190S-infected C. parasitica strain Δdcl-2 was markedly less virulent than wild type and virus-free Δdcl-2 C. parasitica strains. Furthermore, the hypovirulent HvV190S-infected C. parasitica Δdcl-2 strain exhibited strong antifungal activity in dual culture with the plant pathogenic fungus Sclerotinia sclerotiorum. No such inhibitory activity was observed in comparable dual cultures with wild type and virus-free Δdcl-2 C. parasitica strains. The discovery that infection with HvV190S induced a hypovirulent phenotype in a heterologous plant pathogenic host is very significant since it might be possible to convert other economically important plant pathogenic fungi to hypovirulence using HvV190S.
Hiromitsu Moriyama - One of the best experts on this subject based on the ideXlab platform.
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Chrysoviruses (Chrysoviridae) - General Features and Chrysovirus-Related Viruses
Encyclopedia of Virology, 2021Co-Authors: Ioly Kotta-loizou, José R Castón, Robert H. A. Coutts, Hiromitsu Moriyama, Said A GhabrialAbstract:Abstract The family Chrysoviridae encompasses viruses with isometric particles, 35–40 nm in diameter, and multipartite double-stranded RNA genomes. The family was recently reorganized to accommodate two genera, AlphaChrysovirus and BetaChrysovirus, which infect fungi and are also associated with plants and insects. Chrysoviruses are transmitted intracellularly; both vertically from parent to offspring and horizontally from one isolate to another, and may cause hypovirulence in their fungal hosts.
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Population Structure of Double-Stranded RNA Mycoviruses That Infect the Rice Blast Fungus Magnaporthe oryzae in Japan
Frontiers in microbiology, 2020Co-Authors: Yuta Owashi, Mitsuhiro Aihara, Tohru Teraoka, Tsutomu Arie, Hiromitsu Moriyama, Ken KomatsuAbstract:Various viruses infect Magnaporthe oryzae (syn., Pyricularia oryzae), which is a well-studied fungus that causes rice blast disease. Most research has focused on the discovery of new viruses and the hypovirulence-associated traits conferred by them. Therefore, the diversity and prevalence of viruses in wild fungal populations have not been explored. We conducted a comprehensive screening of M. oryzae mycoviruses from various regions in Japan using double-stranded RNA electrophoresis and RT-PCR assays. We detected three mycoviruses, Magnaporthe oryzae virus 2 (MoV2), Magnaporthe oryzae Chrysovirus 1 (MoCV1), and Magnaporthe oryzae partitivirus 1 (MoPV1), among 127 of the 194 M. oryzae strains screened. The most prevalent virus was MoPV1 (58.8%), which often co-infected in a single fungal strain together with MoV2 or MoCV1. MoV2 and MoCV1 were found in 22.7% and 10.8% of strains, respectively, and they were usually distributed in different regions so that mixed-infection with these two mycoviruses was extremely rare. The predominance of MoPV1 in M. oryzae is supported by significant negative values from neutrality tests, which indicate that the population size of MoPV1 tends to increase. Population genetic analyses revealed high nucleotide diversity and the presence of phylogenetically diverse subpopulations among the MoV2 isolates. This was not the case for MoPV1. Furthermore, studies of a virus-cured M. oryzae strain revealed that MoV2 does not cause any abnormalities or symptoms in its host. However, a leaf sheath inoculation assay showed that its presence slightly increased the speed of mycelial growth, compared with virus-free mycelia. These results demonstrate that M. oryzae in Japan harbors diverse dsRNA mycovirus communities with wide variations in their population structures among different viruses.
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Mycovirus-Induced Tenuazonic Acid Production in a Rice Blast Fungus Magnaporthe oryzae.
Frontiers in microbiology, 2020Co-Authors: Akihiro Ninomiya, Syun-ichi Urayama, Shin-ichi Fuji, Hiromitsu Moriyama, Rei Suo, Shiro Itoi, Daisuke HagiwaraAbstract:Fungi are a rich source of natural products with biological activities. In this study, we evaluated viral effects on secondary metabolism of the rice blast fungus Magnaporthe oryzae using an isolate of APU10-199A co-infected with three types of mycoviruses: a totivirus, a Chrysovirus, and a partitivirus. Comparison of the secondary metabolite profile of APU10-199A with that of the strain lacking the totivirus and Chrysovirus showed that a mycotoxin tenuazonic (TeA) acid was produced in a manner dependent on the mycoviruses. Virus reinfection experiments verified that TeA production was dependent on the totivirus. Quantitative reverse transcription PCR and RNA-sequencing analysis indicated the regulatory mechanism underlying viral induction of TeA: the totivirus activates the TeA synthetase gene TAS1 by upregulating the transcription of the gene encoding a Zn(II)2-Cys6-type transcription factor, TAS2. To our knowledge, this is the first report that confirmed mycovirus-associated regulation of secondary metabolism at a transcriptional level by viral reinfection. Because only treatment with dimethyl sulfoxide has been reported to trigger TeA production in this fungus without gene manipulation, our finding highlights the potential of mycoviruses as an epigenomic regulator of fungal secondary metabolism.
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Analysis of an Intrinsic Mycovirus Associated With Reduced Virulence of the Human Pathogenic Fungus Aspergillus fumigatus.
Frontiers in Microbiology, 2020Co-Authors: Azusa Takahashi-nakaguchi, Syun-ichi Urayama, Hiromitsu Moriyama, Erika Shishido, Misa Yahara, Kanae Sakai, Hiroji Chibana, Katsuhiko Kamei, Tohru GonoiAbstract:Aspergillus fumigatus is an airborne fungal pathogen that causes severe infections with invasive growth in immunocompromised patients. Several mycoviruses have recently been isolated from A. fumigatus strains, but there are presently no reports of mycoviral-mediated reduction or elimination of fungal pathogenicity in vertebrate models. Here, we report the biological features of a novel mycovirus, A. fumigatus Chrysovirus 41362 (AfuCV41362), isolated from the hypovirulent A. fumigatus strain IFM 41362. The AfuCV41362 genome is comprised of four dsRNAs, each of which contains a single ORF (ORF1-4). ORF1 encodes a protein with sequence similarity to RNA-dependent RNA polymerases of viruses in the family Chrysoviridae, while ORF3 encodes a putative capsid protein. Viral RNAs are expressed primarily during the germination stage, and RNA-seq analysis of virus-infected A. fumigatus at the germination stage suggested that the virus suppressed expression of several pathogenicity-associated host genes, including hypoxia adaptation and nitric oxide detoxification genes. In vitro functional analysis revealed that the virus-infected strain had reduced tolerance to environmental stressors. Virus-infected A. fumigatus strain IFM 41362 had reduced virulence in vivo compared to the virus-free strain in a mouse infection model. Furthermore, introduction of the mycovirus to a natively virus-free KU A. fumigatus strain induced virus-infected phenotypes. To identify mycovirus genes responsible for the reduced virulence of A. fumigatus, each viral ORF was ectopically expressed in the virus-free KU strain. Ectopic expression of the individual ORFs only nominally reduced virulence of the host fungus in a mouse infection model. However, we found that ORF3 and ORF4 reduced tolerance to environmental stresses in in vitro analysis. Based on these results, we suggest that the AfuCV41362 mycovirus ORF3 and ORF4 reduce fungal virulence by suppressing stress tolerance together with other viral genes, rather than alone.
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Chrysoviruses in Magnaporthe oryzae
Viruses, 2018Co-Authors: Hiromitsu Moriyama, Tomoya Higashiura, Tuong Minh Le, Syun-ichi Urayama, Ken KomatsuAbstract:Magnaporthe oryzae, the fungus that causes rice blast, is the most destructive pathogen of rice worldwide. A number of M. oryzae mycoviruses have been identified. These include Magnaporthe oryzae. viruses 1, 2, and 3 (MoV1, MoV2, and MoV3) belonging to the genus, Victorivirus, in the family, Totiviridae; Magnaporthe oryzae. partitivirus 1 (MoPV1) in the family, Partitiviridae; Magnaporthe oryzae. Chrysovirus 1 strains A and B (MoCV1-A and MoCV1-B) belonging to cluster II of the family, Chrysoviridae; a mycovirus related to plant viruses of the family, Tombusviridae (Magnaporthe oryzae. virus A); and a (+)ssRNA mycovirus closely related to the ourmia-like viruses (Magnaporthe oryzae. ourmia-like virus 1). Among these, MoCV1-A and MoCV1-B were the first reported mycoviruses that cause hypovirulence traits in their host fungus, such as impaired growth, altered colony morphology, and reduced pigmentation. Recently we reported that, although MoCV1-A infection generally confers hypovirulence to fungi, it is also a driving force behind the development of physiological diversity, including pathogenic races. Another example of modulated pathogenicity caused by mycovirus infection is that of Alternaria alternata Chrysovirus 1 (AaCV1), which is closely related to MoCV1-A. AaCV1 exhibits two contrasting effects: Impaired growth of the host fungus while rendering the host hypervirulent to the plant, through increased production of the host-specific AK-toxin. It is inferred that these mycoviruses might be epigenetic factors that cause changes in the pathogenicity of phytopathogenic fungi.
Syun-ichi Urayama - One of the best experts on this subject based on the ideXlab platform.
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Mycovirus-Induced Tenuazonic Acid Production in a Rice Blast Fungus Magnaporthe oryzae.
Frontiers in microbiology, 2020Co-Authors: Akihiro Ninomiya, Syun-ichi Urayama, Shin-ichi Fuji, Hiromitsu Moriyama, Rei Suo, Shiro Itoi, Daisuke HagiwaraAbstract:Fungi are a rich source of natural products with biological activities. In this study, we evaluated viral effects on secondary metabolism of the rice blast fungus Magnaporthe oryzae using an isolate of APU10-199A co-infected with three types of mycoviruses: a totivirus, a Chrysovirus, and a partitivirus. Comparison of the secondary metabolite profile of APU10-199A with that of the strain lacking the totivirus and Chrysovirus showed that a mycotoxin tenuazonic (TeA) acid was produced in a manner dependent on the mycoviruses. Virus reinfection experiments verified that TeA production was dependent on the totivirus. Quantitative reverse transcription PCR and RNA-sequencing analysis indicated the regulatory mechanism underlying viral induction of TeA: the totivirus activates the TeA synthetase gene TAS1 by upregulating the transcription of the gene encoding a Zn(II)2-Cys6-type transcription factor, TAS2. To our knowledge, this is the first report that confirmed mycovirus-associated regulation of secondary metabolism at a transcriptional level by viral reinfection. Because only treatment with dimethyl sulfoxide has been reported to trigger TeA production in this fungus without gene manipulation, our finding highlights the potential of mycoviruses as an epigenomic regulator of fungal secondary metabolism.
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Analysis of an Intrinsic Mycovirus Associated With Reduced Virulence of the Human Pathogenic Fungus Aspergillus fumigatus.
Frontiers in Microbiology, 2020Co-Authors: Azusa Takahashi-nakaguchi, Syun-ichi Urayama, Hiromitsu Moriyama, Erika Shishido, Misa Yahara, Kanae Sakai, Hiroji Chibana, Katsuhiko Kamei, Tohru GonoiAbstract:Aspergillus fumigatus is an airborne fungal pathogen that causes severe infections with invasive growth in immunocompromised patients. Several mycoviruses have recently been isolated from A. fumigatus strains, but there are presently no reports of mycoviral-mediated reduction or elimination of fungal pathogenicity in vertebrate models. Here, we report the biological features of a novel mycovirus, A. fumigatus Chrysovirus 41362 (AfuCV41362), isolated from the hypovirulent A. fumigatus strain IFM 41362. The AfuCV41362 genome is comprised of four dsRNAs, each of which contains a single ORF (ORF1-4). ORF1 encodes a protein with sequence similarity to RNA-dependent RNA polymerases of viruses in the family Chrysoviridae, while ORF3 encodes a putative capsid protein. Viral RNAs are expressed primarily during the germination stage, and RNA-seq analysis of virus-infected A. fumigatus at the germination stage suggested that the virus suppressed expression of several pathogenicity-associated host genes, including hypoxia adaptation and nitric oxide detoxification genes. In vitro functional analysis revealed that the virus-infected strain had reduced tolerance to environmental stressors. Virus-infected A. fumigatus strain IFM 41362 had reduced virulence in vivo compared to the virus-free strain in a mouse infection model. Furthermore, introduction of the mycovirus to a natively virus-free KU A. fumigatus strain induced virus-infected phenotypes. To identify mycovirus genes responsible for the reduced virulence of A. fumigatus, each viral ORF was ectopically expressed in the virus-free KU strain. Ectopic expression of the individual ORFs only nominally reduced virulence of the host fungus in a mouse infection model. However, we found that ORF3 and ORF4 reduced tolerance to environmental stresses in in vitro analysis. Based on these results, we suggest that the AfuCV41362 mycovirus ORF3 and ORF4 reduce fungal virulence by suppressing stress tolerance together with other viral genes, rather than alone.
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Magnaporthe oryzae Chrysovirus 1 strain D confers growth inhibition to the host fungus and exhibits multiform viral structural proteins.
Virology, 2019Co-Authors: Tomoya Higashiura, Yu Katoh, Osamu Hayashi, Mitsuhiro Aihara, Shu Hase, Syun-ichi Urayama, Shin-ichi Fuji, Toshiyuki Fukuhara, Takashi Kobayashi, Tsutomu ArieAbstract:Abstract A Japanese isolate of Magnaporthe oryzae is infected by Magnaporthe oryzae Chrysovirus 1-D (MoCV1-D), which is classified in cluster II of the family Chrysoviridae. The genome of MoCV1-D consists of five dsRNAs. dsRNAs 1–4 show high identity with those of related MoCV1 viruses, whereas dsRNA5 shows relatively low identity and is sometimes deleted during virus propagation. MoCV1-D causes growth inhibition of its host fungus, and the protein encoded by its dsRNA4 impairs cell growth when expressed in yeast cells. It also causes abnormal pigmentation and colony albinization, and we showed that these phenotypes are associated with reduced accumulation of the melanin biosynthesis intermediate scylatone. MoCV1-D exhibits multiform viral structural proteins during prolonged culture. The original host isolate is co-infected with MoCV1-D, a victorivirus, and a partitivirus, and these mycoviruses are detected in cell-free supernatant fractions after prolonged liquid culturing. Hyphal fusion experiments demonstrated that MoCV1-D is transmissible via anastomosis.
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Chrysoviruses in Magnaporthe oryzae
Viruses, 2018Co-Authors: Hiromitsu Moriyama, Tomoya Higashiura, Tuong Minh Le, Syun-ichi Urayama, Ken KomatsuAbstract:Magnaporthe oryzae, the fungus that causes rice blast, is the most destructive pathogen of rice worldwide. A number of M. oryzae mycoviruses have been identified. These include Magnaporthe oryzae. viruses 1, 2, and 3 (MoV1, MoV2, and MoV3) belonging to the genus, Victorivirus, in the family, Totiviridae; Magnaporthe oryzae. partitivirus 1 (MoPV1) in the family, Partitiviridae; Magnaporthe oryzae. Chrysovirus 1 strains A and B (MoCV1-A and MoCV1-B) belonging to cluster II of the family, Chrysoviridae; a mycovirus related to plant viruses of the family, Tombusviridae (Magnaporthe oryzae. virus A); and a (+)ssRNA mycovirus closely related to the ourmia-like viruses (Magnaporthe oryzae. ourmia-like virus 1). Among these, MoCV1-A and MoCV1-B were the first reported mycoviruses that cause hypovirulence traits in their host fungus, such as impaired growth, altered colony morphology, and reduced pigmentation. Recently we reported that, although MoCV1-A infection generally confers hypovirulence to fungi, it is also a driving force behind the development of physiological diversity, including pathogenic races. Another example of modulated pathogenicity caused by mycovirus infection is that of Alternaria alternata Chrysovirus 1 (AaCV1), which is closely related to MoCV1-A. AaCV1 exhibits two contrasting effects: Impaired growth of the host fungus while rendering the host hypervirulent to the plant, through increased production of the host-specific AK-toxin. It is inferred that these mycoviruses might be epigenetic factors that cause changes in the pathogenicity of phytopathogenic fungi.
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molecular characterization of a novel mycovirus in alternaria alternata manifesting two sided effects down regulation of host growth and up regulation of host plant pathogenicity
Virology, 2018Co-Authors: Ryo Okada, Ken Komatsu, Tsutomu Arie, Syun-ichi Urayama, Toshiyuki Fukuhara, Shun Ichinose, Kana Takeshita, Atsushi Ishihara, Mayumi Egusa, Motoichiro KodamaAbstract:Abstract A double-stranded RNA (dsRNA) mycovirus was detected in a strain of Alternaria alternata showing impaired growth phenotypes. The A. alternata strain is the Japanese pear pathotype, which produces a host-specific AK-toxin. Sequence analysis of the viral genome dsRNAs revealed that this mycovirus consists of five dsRNAs and is evolutionarily related to members of the family Chrysoviridae; the virus was named Alternaria alternata Chrysovirus 1 (AaCV1). AaCV1-ORF2 protein accumulated in dsRNA-high-titer sub-isolates with severely impaired phenotypes; heterologous AaCV1-ORF2 overexpression in Saccharomyces cerevisiae caused growth inhibition. In contrast to this yeast growth inhibition phenomenon, the dsRNA-high-titer isolates displayed enhanced pathogenicity against Japanese pear plants, in accordance with a 13-fold increase in AK-toxin level in one such isolate. These findings indicated that AaCV1 is a novel mycovirus that exhibits two contrasting effects, impairing growth of the host fungus while rendering the host ‘hypervirulent’ to the plant.
Tsutomu Arie - One of the best experts on this subject based on the ideXlab platform.
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Population Structure of Double-Stranded RNA Mycoviruses That Infect the Rice Blast Fungus Magnaporthe oryzae in Japan
Frontiers in microbiology, 2020Co-Authors: Yuta Owashi, Mitsuhiro Aihara, Tohru Teraoka, Tsutomu Arie, Hiromitsu Moriyama, Ken KomatsuAbstract:Various viruses infect Magnaporthe oryzae (syn., Pyricularia oryzae), which is a well-studied fungus that causes rice blast disease. Most research has focused on the discovery of new viruses and the hypovirulence-associated traits conferred by them. Therefore, the diversity and prevalence of viruses in wild fungal populations have not been explored. We conducted a comprehensive screening of M. oryzae mycoviruses from various regions in Japan using double-stranded RNA electrophoresis and RT-PCR assays. We detected three mycoviruses, Magnaporthe oryzae virus 2 (MoV2), Magnaporthe oryzae Chrysovirus 1 (MoCV1), and Magnaporthe oryzae partitivirus 1 (MoPV1), among 127 of the 194 M. oryzae strains screened. The most prevalent virus was MoPV1 (58.8%), which often co-infected in a single fungal strain together with MoV2 or MoCV1. MoV2 and MoCV1 were found in 22.7% and 10.8% of strains, respectively, and they were usually distributed in different regions so that mixed-infection with these two mycoviruses was extremely rare. The predominance of MoPV1 in M. oryzae is supported by significant negative values from neutrality tests, which indicate that the population size of MoPV1 tends to increase. Population genetic analyses revealed high nucleotide diversity and the presence of phylogenetically diverse subpopulations among the MoV2 isolates. This was not the case for MoPV1. Furthermore, studies of a virus-cured M. oryzae strain revealed that MoV2 does not cause any abnormalities or symptoms in its host. However, a leaf sheath inoculation assay showed that its presence slightly increased the speed of mycelial growth, compared with virus-free mycelia. These results demonstrate that M. oryzae in Japan harbors diverse dsRNA mycovirus communities with wide variations in their population structures among different viruses.
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Magnaporthe oryzae Chrysovirus 1 strain D confers growth inhibition to the host fungus and exhibits multiform viral structural proteins.
Virology, 2019Co-Authors: Tomoya Higashiura, Yu Katoh, Osamu Hayashi, Mitsuhiro Aihara, Shu Hase, Syun-ichi Urayama, Shin-ichi Fuji, Toshiyuki Fukuhara, Takashi Kobayashi, Tsutomu ArieAbstract:Abstract A Japanese isolate of Magnaporthe oryzae is infected by Magnaporthe oryzae Chrysovirus 1-D (MoCV1-D), which is classified in cluster II of the family Chrysoviridae. The genome of MoCV1-D consists of five dsRNAs. dsRNAs 1–4 show high identity with those of related MoCV1 viruses, whereas dsRNA5 shows relatively low identity and is sometimes deleted during virus propagation. MoCV1-D causes growth inhibition of its host fungus, and the protein encoded by its dsRNA4 impairs cell growth when expressed in yeast cells. It also causes abnormal pigmentation and colony albinization, and we showed that these phenotypes are associated with reduced accumulation of the melanin biosynthesis intermediate scylatone. MoCV1-D exhibits multiform viral structural proteins during prolonged culture. The original host isolate is co-infected with MoCV1-D, a victorivirus, and a partitivirus, and these mycoviruses are detected in cell-free supernatant fractions after prolonged liquid culturing. Hyphal fusion experiments demonstrated that MoCV1-D is transmissible via anastomosis.
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molecular characterization of a novel mycovirus in alternaria alternata manifesting two sided effects down regulation of host growth and up regulation of host plant pathogenicity
Virology, 2018Co-Authors: Ryo Okada, Ken Komatsu, Tsutomu Arie, Syun-ichi Urayama, Toshiyuki Fukuhara, Shun Ichinose, Kana Takeshita, Atsushi Ishihara, Mayumi Egusa, Motoichiro KodamaAbstract:Abstract A double-stranded RNA (dsRNA) mycovirus was detected in a strain of Alternaria alternata showing impaired growth phenotypes. The A. alternata strain is the Japanese pear pathotype, which produces a host-specific AK-toxin. Sequence analysis of the viral genome dsRNAs revealed that this mycovirus consists of five dsRNAs and is evolutionarily related to members of the family Chrysoviridae; the virus was named Alternaria alternata Chrysovirus 1 (AaCV1). AaCV1-ORF2 protein accumulated in dsRNA-high-titer sub-isolates with severely impaired phenotypes; heterologous AaCV1-ORF2 overexpression in Saccharomyces cerevisiae caused growth inhibition. In contrast to this yeast growth inhibition phenomenon, the dsRNA-high-titer isolates displayed enhanced pathogenicity against Japanese pear plants, in accordance with a 13-fold increase in AK-toxin level in one such isolate. These findings indicated that AaCV1 is a novel mycovirus that exhibits two contrasting effects, impairing growth of the host fungus while rendering the host ‘hypervirulent’ to the plant.
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Infection by Magnaporthe oryzae Chrysovirus 1 strain A triggers reduced virulence and pathogenic race conversion of its host fungus, Magnaporthe oryzae
Journal of General Plant Pathology, 2018Co-Authors: Mitsuhiro Aihara, Tomoya Higashiura, Ken Komatsu, Minh Tuong Le, Yu Katoh, Tohru Teraoka, Tsutomu Arie, Syun-ichi Urayama, Toshiyuki Fukuhara, Hiromitsu MoriyamaAbstract:Magnaporthe oryzae Chrysovirus 1 strain A (MoCV1-A) is associated with an impaired growth phenotype of its host fungus, Magnaporthe oryzae . In this report, we assayed the virulence and pathogenicity of MoCV1-A-infected and MoCV1-A-free M. oryzae on rice plants. MoCV1-A infection did not affect virulence-associated fungal traits, such as conidial germination and appressorium formation. However, after punch inoculation of leaves on rice plants, MoCV1-A-infected strain formed smaller lesions than the MoCV1-A-free strain did on all rice varieties tested, showing that MoCV1-A infection resulted in reduced virulence of host fungi in rice plants. In contrast, after spray inoculation of rice seedlings, in some cases, MoCV1-A-infected and MoCV1-A-free strains caused different lesion types (resistance to susceptible, or vice versa) on individual international differential rice varieties. However, we did not find any gain/loss of the fungal avirulence genes by PCR, suggesting that MoCV1-A infection can convert the pathogenicity of the host M. oryzae from avirulence to virulence, or from virulence to avirulence, depending on the rice variety. We also confirmed the correlation of these race conversion events and invasive hyphae growth of the fungi in a leaf sheath inoculation assay. These data suggested that MoCV1-A infection generally confers hypovirulence to the fungal host and could be a driving force to generate physiological diversity, including pathogenic races.
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Suppressive effects of mycoviral proteins encoded by Magnaporthe oryzae Chrysovirus 1 strain A on conidial germination of the rice blast fungus.
Virus research, 2016Co-Authors: Syun-ichi Urayama, Ken Komatsu, Yu Katoh, Tohru Teraoka, Tsutomu Arie, Toshiyuki Fukuhara, Yuri Kimura, Tomoko Ohta, Nobuya Onozuka, Hiromitsu MoriyamaAbstract:Magnaporthe oryzae Chrysovirus 1 strain A (MoCV1-A) is the causal agent of growth repression and attenuated virulence (hypovirulence) of the rice blast fungus, Magnaporthe oryzae. We previously revealed that heterologous expression of the MoCV1-A ORF4 protein resulted in cytological damage to the yeasts Saccharomyces cerevisiae and Cryptococcus neoformans. Since the ORF4 protein is one of the components of viral particles, we evaluated the inhibitory effects of the purified virus particle against the conidial germination of M. oryzae, and confirmed its suppressive effects. Recombinant MoCV1-A ORF4 protein produced in Pichia pastoris was also effective for suppression of conidial germination of M. oryzae. MoCV1-A ORF4 protein sequence showed significant similarity to 6 related mycoviral proteins; Botrysphaeria dothidea Chrysovirus 1, two Fusarium graminearum viruses, Fusarium oxysporum f. sp. dianthi mycovirus 1, Penicillium janczewski Chrysovirus and Agaricus bisporus virus 1 in the Chrysoviridae family. Multiple alignments of the ORF4-related protein sequences showed that their central regions (210-591 aa in MoCV1-A ORF4) are relatively conserved. Indeed, yeast transformants expressing the conserved central region of MoCV1-A ORF4 protein (325-575 aa) showed similar impaired growth phenotypes as those observed in yeasts expressing the full-length MoCV1-A ORF4 protein. These data suggest that the mycovirus itself and its encoded viral protein can be useful as anti-fungal proteins to control rice blast disease caused by M. oryzae and other pathogenic fungi.
Wendy M Havens - One of the best experts on this subject based on the ideXlab platform.
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Reprint of "The victorivirus Helminthosporium victoriae virus 190S is the primary cause of disease/hypovirulence in its natural host and a heterologous host".
Virus research, 2016Co-Authors: Wendy M Havens, Nobuhiro Suzuki, Said A GhabrialAbstract:A transmissible disease of the plant pathogenic fungus Helminthosporium victoriae, the causal agent of Victoria blight of oats, was reported more than 50 years ago. Diseased, but not normal, isolates, of H. victoriae contain two distinct viruses designated according to their sedimentation values as victorivirus Helminthosporium victoriae virus 190S (HvV190S) and Chrysovirus Helminthosporium victoriae 145S (HvV145S). Although a viral etiology of the disease was previously proposed, conclusive evidence was lacking. Here we present unequivocal evidence based on transfecting virus-free H. victoriae protoplasts with purified virus particles showing that HvV190S is essential for disease development. Furthermore, we show an expansion of the host range of HvV190S to include Cryphonectria parasitica and we also show similarity in a subset of phenotypic traits between HvV190S-infected RNA silencing deficient mutant (Δdcl-2) of C. parasitica and a strain of H. victoriae. In virulence assays on detached American chestnut branches and Red Delicious apple fruits, HvV190S-infected C. parasitica strain Δdcl-2 was markedly less virulent than wild type and virus-free Δdcl-2 C. parasitica strains. Furthermore, the hypovirulent HvV190S-infected C. parasitica Δdcl-2 strain exhibited strong antifungal activity in dual culture with the plant pathogenic fungus Sclerotinia sclerotiorum. No such inhibitory activity was observed in comparable dual cultures with wild type and virus-free Δdcl-2 C. parasitica strains. The discovery that infection with HvV190S induced a hypovirulent phenotype in a heterologous plant pathogenic host is very significant since it might be possible to convert other economically important plant pathogenic fungi to hypovirulence using HvV190S.
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the victorivirus helminthosporium victoriae virus 190s is the primary cause of disease hypovirulence in its natural host and a heterologous host
Virus Research, 2016Co-Authors: Wendy M Havens, Nobuhiro Suzuki, Said A GhabrialAbstract:A transmissible disease of the plant pathogenic fungus Helminthosporium victoriae, the causal agent of Victoria blight of oats, was reported more than 50 years ago. Diseased, but not normal, isolates, of H. victoriae contain two distinct viruses designated according to their sedimentation values as victorivirus Helminthosporium victoriae virus 190S (HvV190S) and Chrysovirus Helminthosporium victoriae 145S (HvV145S). Although a viral etiology of the disease was previously proposed, conclusive evidence was lacking. Here we present unequivocal evidence based on transfecting virus-free H. victoriae protoplasts with purified virus particles showing that HvV190S is essential for disease development. Furthermore, we show an expansion of the host range of HvV190S to include Cryphonectria parasitica and we also show similarity in a subset of phenotypic traits between HvV190S-infected RNA silencing deficient mutant (Δdcl-2) of C. parasitica and a strain of H. victoriae. In virulence assays on detached American chestnut branches and Red Delicious apple fruits, HvV190S-infected C. parasitica strain Δdcl-2 was markedly less virulent than wild type and virus-free Δdcl-2 C. parasitica strains. Furthermore, the hypovirulent HvV190S-infected C. parasitica Δdcl-2 strain exhibited strong antifungal activity in dual culture with the plant pathogenic fungus Sclerotinia sclerotiorum. No such inhibitory activity was observed in comparable dual cultures with wild type and virus-free Δdcl-2 C. parasitica strains. The discovery that infection with HvV190S induced a hypovirulent phenotype in a heterologous plant pathogenic host is very significant since it might be possible to convert other economically important plant pathogenic fungi to hypovirulence using HvV190S.
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The victorivirus Helminthosporium victoriae virus 190S is the primary cause of disease/hypovirulence in its natural host and a heterologous host.
Virus Research, 2015Co-Authors: Wendy M Havens, Nobuhiro Suzuki, Said A GhabrialAbstract:A transmissible disease of the plant pathogenic fungus Helminthosporium victoriae, the causal agent of Victoria blight of oats, was reported more than 50 years ago. Diseased, but not normal, isolates, of H. victoriae contain two distinct viruses designated according to their sedimentation values as victorivirus Helminthosporium victoriae virus 190S (HvV190S) and Chrysovirus Helminthosporium victoriae 145S (HvV145S). Although a viral etiology of the disease was previously proposed, conclusive evidence was lacking. Here we present unequivocal evidence based on transfecting virus-free H. victoriae protoplasts with purified virus particles showing that HvV190S is essential for disease development. Furthermore, we show an expansion of the host range of HvV190S to include Cryphonectria parasitica and we also show similarity in a subset of phenotypic traits between HvV190S-infected RNA silencing deficient mutant (Δdcl-2) of C. parasitica and a strain of H. victoriae. In virulence assays on detached American chestnut branches and Red Delicious apple fruits, HvV190S-infected C. parasitica strain Δdcl-2 was markedly less virulent than wild type and virus-free Δdcl-2 C. parasitica strains. Furthermore, the hypovirulent HvV190S-infected C. parasitica Δdcl-2 strain exhibited strong antifungal activity in dual culture with the plant pathogenic fungus Sclerotinia sclerotiorum. No such inhibitory activity was observed in comparable dual cultures with wild type and virus-free Δdcl-2 C. parasitica strains. The discovery that infection with HvV190S induced a hypovirulent phenotype in a heterologous plant pathogenic host is very significant since it might be possible to convert other economically important plant pathogenic fungi to hypovirulence using HvV190S.
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A cellular protein with an RNA-binding activity co-purifies with viral dsRNA from mycovirus-infected Helminthosporium victoriae.
Virology, 2000Co-Authors: Ana I. Soldevila, Wendy M Havens, Said A GhabrialAbstract:Abstract A cellular protein that co-purifies with mycoviral dsRNA was isolated from the plant pathogenic fungus Helminthosporium victoriae (telomorph: Cochliobolus victoriae ) infected with two viruses, the totivirus Helminthosporium victoriae 190S virus and the Chrysovirus-like Helminthosporium victoriae 145S virus (Hv145SV). The cellular protein, which was, designated Hv-p68, accumulated to higher levels in virus-infected isolates compared to virus-free ones. The majority of the Hv145S dsRNAs were found in association with Hv-p68 and not packaged in virions. Hv-p68 could also be detected as a minor component of the virus capsid. Evidence is presented that Hv-p68 occurs in vivo as an octamer and that it possesses RNA-binding activities. Based on partial amino acid sequence analysis, Hv-p68 was shown to share significant sequence identity with alcohol oxidases from methylotrophic yeasts. Hv-p68 is proposed to play a role in viral RNA packaging/replication and in regulating viral pathogenesis.