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Hiromitsu Moriyama - 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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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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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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a dsrna mycovirus Magnaporthe Oryzae chrysovirus 1 b suppresses vegetative growth and development of the rice blast fungus
Virology, 2014Co-Authors: Syun-ichi Urayama, Yu Katoh, Tohru Teraoka, Tsutomu Arie, Toshiyuki Fukuhara, Hirofumi Sakoda, Ryoko Takai, Hiromitsu MoriyamaAbstract:A double-stranded RNA (dsRNA) mycovirus was found in isolate S-0412-II 2a of the rice blast fungus Magnaporthe Oryzae. Sequence analysis of the five dsRNA segments (dsRNA1 through dsRNA5) revealed that this mycovirus is closely related to Magnaporthe Oryzae chrysovirus 1-A (MoCV1-A), tentatively classified as a member of the Chrysoviridae; therefore, it was named Magnaporthe Oryzae chrysovirus 1-B (MoCV1-B). Virus particles were spherical and composed of the ORF1, ORF3 and ORF4 proteins. MoCV1-B-infected isolate S-0412-II 2a showed a more severe impaired phenotype than the MoCV1-A-infected isolate. In a virus-cured isolate, normal growth was restored, implied that MoCV1-B could be involved in this observed phenotype. An unanticipated result was the occurrence of a fungal isolate lacking dsRNA5. The nonessential dsRNA5 had higher sequence identity (96%) with dsRNA5 of MoCV1-A than with the other dsRNA segments (71-79%), indicating that dsRNA5 could be a portable genomic element between MoCV1-A and MoCV1-B.
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mycoviruses related to chrysovirus affect vegetative growth in the rice blast fungus Magnaporthe Oryzae
Journal of General Virology, 2010Co-Authors: Syun-ichi Urayama, Yu Suzuki, Sachie Kato, Nanako Aoki, Minh Tuong Le, Tohru Teraoka, Tsutomu Arie, Toshiyuki Fukuhara, Hiromitsu MoriyamaAbstract:Mycoviruses causing impaired growth and abnormal pigmentation of the host were found in the rice blast fungus, Magnaporthe Oryzae. Four dsRNAs, dsRNA 1 (3554 bp), dsRNA 2 (3250 bp), dsRNA 3 (3074 bp) and dsRNA 4 (3043 bp), were detected in isolate S-0412-II 1a of M. Oryzae. By picking up single conidia of S-0412-II 1a, cured strains of the fungus were isolated that had completely lost the mycovirus. The cured strains had normal mycelial growth and pigmentation, suggesting that this mycovirus modulates host traits. The buoyant densities of isometric virus particles (∼35 nm diameter) containing these dsRNAs in CsCl ranged from 1.37 to 1.40 g cm−3. The single ORF (3384 nt) of dsRNA 1 encoded a gene product highly homologous to the viral RNA-dependent RNA polymerase of members of the family Chrysoviridae. It is noteworthy that mycovirus S-0412-II 1a was detected not only in host cells but also in culture supernatant. Furthermore, abnormal aggregation of mycelia was observed after adding the mycovirus-containing culture supernatant to an uninfected strain of M. Oryzae and mycoviral dsRNAs were detectable from the aggregated mycelia. This novel dsRNA mycovirus was named Magnaporthe Oryzae chrysovirus 1.
Nicholas J. Talbot - One of the best experts on this subject based on the ideXlab platform.
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The biology of blast: Understanding how Magnaporthe Oryzae invades rice plants
Fungal Biology Reviews, 2011Co-Authors: Rita Galhano, Nicholas J. TalbotAbstract:Abstract Rice blast is one of the world’s most serious plant diseases and a significant threat to global food security. To invade rice plants, the blast fungus Magnaporthe Oryzae forms specialised cells called appressoria that generate pressure and physical force to rupture the leaf cuticle. Recent evidence suggests that appressorium development is controlled by cell cycle checkpoints and involves autophagy. This culminates in programmed cell death of the fungal conidium and recycling of its contents to the appressorium. M. Oryzae has evolved specialised regulatory mechanisms to respond to the nutrient-free environment of the rice leaf surface and its physical and chemical characteristics, in order to gain entry to the plant
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under pressure investigating the biology of plant infection by Magnaporthe Oryzae
Nature Reviews Microbiology, 2009Co-Authors: Richard A. Wilson, Nicholas J. TalbotAbstract:Almost one-quarter of the calories consumed by the global human population is derived from rice. Epidemics of rice blast disease, which are caused by the filamentous fungus Magnaporthe Oryzae, therefore represent a major threat to global food stocks. This Review discusses how functional genomic approaches are shedding light on the mechanisms used by M. Oryzae during plant infection.
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Under pressure: investigating the biology of plant infection by Magnaporthe Oryzae
Nature Reviews Microbiology, 2009Co-Authors: Richard A. Wilson, Nicholas J. TalbotAbstract:Almost one-quarter of the calories consumed by the global human population is derived from rice. Epidemics of rice blast disease, which are caused by the filamentous fungus Magnaporthe Oryzae , therefore represent a major threat to global food stocks. This Review discusses how functional genomic approaches are shedding light on the mechanisms used by M. Oryzae during plant infection. Rice blast is caused by the ascomycete fungus Magnaporthe Oryzae and is the most serious disease of cultivated rice. The fungus is genetically tractable, has a sequenced genome and is experimentally amenable to study using functional genomics and cell biology. The fungus elaborates specialized cells called appressoria to infect plants. Appressorium development is cell cycle regulated and involves autophagic programmed cell death of the fungal spore. The cyclic AMP response pathway and the Pmk1 mitogen-activated protein kinase kinase pathway are necessary for appressorium development. Appressorium turgor generation involves accumulation of compatible solutes, including glycerol, which are derived from storage products in spores. Glycerol accumulation and melanization of the cell wall allow the deployment of sufficient turgor to breach the plant cuticle. The fungus spreads biotrophically in epidermal cells and might use protein effectors and/or secondary metabolites to suppress host defences. Disease symptoms involve necrosis of plant cells, which produces characteristic spreading lesions from which the fungus sporulates. Disease control by deployment of resistance genes, biotechnological approaches and development of new fungicides is an important aim of research on rice blast. The filamentous fungus Magnaporthe Oryzae causes rice blast, the most serious disease of cultivated rice. Cellular differentiation of M. Oryzae forms an infection structure called the appressorium, which generates enormous cellular turgor that is sufficient to rupture the plant cuticle. Here, we show how functional genomics approaches are providing new insight into the genetic control of plant infection by M. Oryzae . We also look ahead to the key questions that need to be addressed to provide a better understanding of the molecular processes that lead to plant disease and the prospects for sustainable control of rice blast.
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Under pressure: Investigating the biology of plant infection by Magnaporthe Oryzae
Nature reviews. Microbiology, 2009Co-Authors: Richard A. Wilson, Nicholas J. TalbotAbstract:The filamentous fungus Magnaporthe Oryzae causes rice blast, the most serious disease of cultivated rice. Cellular differentiation of M. Oryzae forms an infection structure called the appressorium, which generates enormous cellular turgor that is sufficient to rupture the plant cuticle. Here, we show how functional genomics approaches are providing new insight into the genetic control of plant infection by M. Oryzae. We also look ahead to the key questions that need to be addressed to provide a better understanding of the molecular processes that lead to plant disease and the prospects for sustainable control of rice blast.
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Silencing the crowd: high‐throughput functional genomics in Magnaporthe Oryzae
Molecular microbiology, 2008Co-Authors: Zaira Caracuel-rios, Nicholas J. TalbotAbstract:Summary A new high-throughput RNA-silencing system has been developed for use in the rice blast fungus Magnaporthe Oryzae, allowing rapid generation of transformants in which individual genes have been silenced. Development of this system will allow large-scale functional analysis of genes in the fungus to define the cellular processes required for plant infection and disease symptoms. Functional analysis of 37 genes predicted to be involved in calcium signalling was carried out by RNA silencing to validate the new strategy and has provided new insight into the role of calcium-mediated signal transduction in plant pathogenic fungi.
Mark L. Farman - One of the best experts on this subject based on the ideXlab platform.
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Subtelomere Organization, Evolution, and Dynamics in the Rice Blast Fungus Magnaporthe Oryzae
Subtelomeres, 2013Co-Authors: Mark L. Farman, Olga Novikova, John H Starnes, David W. ThornburyAbstract:Magnaporthe Oryzae is a filamentous, ascomycete fungus best known as the causal agent of a devastating disease of rice known as blast. In addition to being a pathogen of rice, it also causes diseases on other important crops, including wheat, millets, and forage grasses, and on turf grasses such as perennial ryegrass and St. Augustinegrass. Despite the species’ broad host range, fungal isolates from one host genus usually are unable to infect other host genera. Such specificity can also be manifested at the subspecies level, such that an isolate from one rice cultivar is often unable to infect other cultivars.
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Telomere hypervariability in Magnaporthe Oryzae
Molecular Plant Pathology, 2005Co-Authors: Mark L. FarmanAbstract:SUMMARY The gray leaf spot disease of perennial ryegrass and tall fescue is caused by the fungus Magnaporthe Oryzae (anamorph = Pyricularia Oryzae). A collection of single-copy and repetitive DNA markers was used to investigate genetic diversity among 22 isolates of the gray leaf spot pathogen. The single-copy DNA markers revealed only three polymorphisms among 95 restriction fragments spanning ∼0.6% of the genome. In addition, Southern hybridization analysis and mating tests revealed that all isolates possessed the MAT1-2 mating-type allele. Fingerprinting of repetitive DNA loci using the Pot2 and MGR583 probes also revealed a high degree of genetic similarity (> 85%) among isolates. These data are consistent with the gray leaf spot pathogens having a recent evolutionary origin. In contrast to the results obtained with probes for internal chromosome loci, a telomere probe revealed that the chromosome ends of the very same isolates are highly divergent, with most isolates sharing less than 20% fingerprint similarity with any other isolate. Telomere mutations arise extremely frequently and changes in telomere fingerprint profiles were readily observed during vegetative growth and among cultures derived from single spores isolated from agar medium and from lesions on perennial ryegrass leaves.
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Telomere hypervariability in Magnaporthe Oryzae.
Molecular plant pathology, 2005Co-Authors: Mark L. Farman, Yun-sik KimAbstract:SUMMARY The gray leaf spot disease of perennial ryegrass and tall fescue is caused by the fungus Magnaporthe Oryzae (anamorph = Pyricularia Oryzae). A collection of single-copy and repetitive DNA markers was used to investigate genetic diversity among 22 isolates of the gray leaf spot pathogen. The single-copy DNA markers revealed only three polymorphisms among 95 restriction fragments spanning approximately 0.6% of the genome. In addition, Southern hybridization analysis and mating tests revealed that all isolates possessed the MAT1-2 mating-type allele. Fingerprinting of repetitive DNA loci using the Pot2 and MGR583 probes also revealed a high degree of genetic similarity (> 85%) among isolates. These data are consistent with the gray leaf spot pathogens having a recent evolutionary origin. In contrast to the results obtained with probes for internal chromosome loci, a telomere probe revealed that the chromosome ends of the very same isolates are highly divergent, with most isolates sharing less than 20% fingerprint similarity with any other isolate. Telomere mutations arise extremely frequently and changes in telomere fingerprint profiles were readily observed during vegetative growth and among cultures derived from single spores isolated from agar medium and from lesions on perennial ryegrass leaves.
Syun-ichi Urayama - One of the best experts on this subject based on the ideXlab platform.
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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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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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a dsrna mycovirus Magnaporthe Oryzae chrysovirus 1 b suppresses vegetative growth and development of the rice blast fungus
Virology, 2014Co-Authors: Syun-ichi Urayama, Yu Katoh, Tohru Teraoka, Tsutomu Arie, Toshiyuki Fukuhara, Hirofumi Sakoda, Ryoko Takai, Hiromitsu MoriyamaAbstract:A double-stranded RNA (dsRNA) mycovirus was found in isolate S-0412-II 2a of the rice blast fungus Magnaporthe Oryzae. Sequence analysis of the five dsRNA segments (dsRNA1 through dsRNA5) revealed that this mycovirus is closely related to Magnaporthe Oryzae chrysovirus 1-A (MoCV1-A), tentatively classified as a member of the Chrysoviridae; therefore, it was named Magnaporthe Oryzae chrysovirus 1-B (MoCV1-B). Virus particles were spherical and composed of the ORF1, ORF3 and ORF4 proteins. MoCV1-B-infected isolate S-0412-II 2a showed a more severe impaired phenotype than the MoCV1-A-infected isolate. In a virus-cured isolate, normal growth was restored, implied that MoCV1-B could be involved in this observed phenotype. An unanticipated result was the occurrence of a fungal isolate lacking dsRNA5. The nonessential dsRNA5 had higher sequence identity (96%) with dsRNA5 of MoCV1-A than with the other dsRNA segments (71-79%), indicating that dsRNA5 could be a portable genomic element between MoCV1-A and MoCV1-B.
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mycoviruses related to chrysovirus affect vegetative growth in the rice blast fungus Magnaporthe Oryzae
Journal of General Virology, 2010Co-Authors: Syun-ichi Urayama, Yu Suzuki, Sachie Kato, Nanako Aoki, Minh Tuong Le, Tohru Teraoka, Tsutomu Arie, Toshiyuki Fukuhara, Hiromitsu MoriyamaAbstract:Mycoviruses causing impaired growth and abnormal pigmentation of the host were found in the rice blast fungus, Magnaporthe Oryzae. Four dsRNAs, dsRNA 1 (3554 bp), dsRNA 2 (3250 bp), dsRNA 3 (3074 bp) and dsRNA 4 (3043 bp), were detected in isolate S-0412-II 1a of M. Oryzae. By picking up single conidia of S-0412-II 1a, cured strains of the fungus were isolated that had completely lost the mycovirus. The cured strains had normal mycelial growth and pigmentation, suggesting that this mycovirus modulates host traits. The buoyant densities of isometric virus particles (∼35 nm diameter) containing these dsRNAs in CsCl ranged from 1.37 to 1.40 g cm−3. The single ORF (3384 nt) of dsRNA 1 encoded a gene product highly homologous to the viral RNA-dependent RNA polymerase of members of the family Chrysoviridae. It is noteworthy that mycovirus S-0412-II 1a was detected not only in host cells but also in culture supernatant. Furthermore, abnormal aggregation of mycelia was observed after adding the mycovirus-containing culture supernatant to an uninfected strain of M. Oryzae and mycoviral dsRNAs were detectable from the aggregated mycelia. This novel dsRNA mycovirus was named Magnaporthe Oryzae chrysovirus 1.
Richard A. Wilson - One of the best experts on this subject based on the ideXlab platform.
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Spermine-mediated tight sealing of the Magnaporthe Oryzae appressorial pore–rice leaf surface interface
Nature Microbiology, 2020Co-Authors: Raquel O. Rocha, Christian Elowsky, Ngoc T. T. Pham, Richard A. WilsonAbstract:Cellular adhesion mediates many important plant–microbe interactions. In the devastating blast fungus Magnaporthe Oryzae ^ 1 , powerful glycoprotein-rich mucilage adhesives^ 2 cement melanized and pressurized dome-shaped infection cells—appressoria—to host rice leaf surfaces. Enormous internal turgor pressure is directed onto a penetration peg emerging from the unmelanized, thin-walled pore at the appressorial base^ 1 – 4 , forcing it through the leaf cuticle where it elongates invasive hyphae in underlying epidermal cells^ 5 . Mucilage sealing around the appressorial pore facilitates turgor build-up^ 2 , but the molecular underpinnings of mucilage secretion and appressorial adhesion are unknown. Here, we discovered an unanticipated and sole role for spermine in facilitating mucilage production by mitigating endoplasmic reticulum (ER) stress in the developing appressorium. Mutant strains lacking the spermine synthase-encoding gene SPS1 progressed through all stages of appressorial development, including penetration peg formation, but cuticle penetration was unsuccessful due to reduced appressorial adhesion, which led to solute leakage. Mechanistically, spermine neutralized off-target oxygen free radicals produced by NADPH oxidase-1 (Nox1)^ 3 , 6 that otherwise elicited ER stress and the unfolded protein response, thereby critically reducing mucilage secretion. Our study reveals that spermine metabolism via redox buffering of the ER underpins appressorial adhesion and rice cell invasion and provides insights into a process that is fundamental to host plant infection. Spermine facilitates mucilage production and rice cell invasion by mitigating endoplasmic reticulum stress in the developing Magnaporthe Oryzae appressorium.
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The Magnaporthe Oryzae nitrooxidative stress response suppresses rice innate immunity during blast disease
Nature Microbiology, 2017Co-Authors: Margarita Marroquin-guzman, David Hartline, Janet D. Wright, Christian Elowsky, Travis J. Bourret, Richard A. WilsonAbstract:Magnaporthe Oryzae nitronate monooxygenase NMO2 is shown to be required for prevention of damaging lipid nitration and host ROS-mediated innate immune responses in rice plants, enabling biotrophic growth of the rice blast fungus. Understanding how microorganisms manipulate plant innate immunity and colonize host cells is a major goal of plant pathology. Here, we report that the fungal nitrooxidative stress response suppresses host defences to facilitate the growth and development of the important rice pathogen Magnaporthe Oryzae in leaf cells. Nitronate monooxygenases encoded by NMO genes catalyse the oxidative denitrification of nitroalkanes. We show that the M. Oryzae NMO2 gene is required for mitigating damaging lipid nitration under nitrooxidative stress conditions and, consequently, for using nitrate and nitrite as nitrogen sources. On plants, the Δ nmo2 mutant strain penetrated host cuticles like wild type, but invasive hyphal growth in rice cells was restricted and elicited plant immune responses that included the formation of cellular deposits and a host reactive oxygen species burst. Development of the M. Oryzae effector-secreting biotrophic interfacial complex (BIC) was misregulated in the Δ nmo2 mutant. Inhibiting or quenching host reactive oxygen species suppressed rice innate immune responses and allowed the Δ nmo2 mutant to grow and develop normally in infected cells. NMO2 is thus essential for mitigating nitrooxidative cellular damage and, in rice cells, maintaining redox balance to avoid triggering plant defences that impact M. Oryzae growth and BIC development.
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under pressure investigating the biology of plant infection by Magnaporthe Oryzae
Nature Reviews Microbiology, 2009Co-Authors: Richard A. Wilson, Nicholas J. TalbotAbstract:Almost one-quarter of the calories consumed by the global human population is derived from rice. Epidemics of rice blast disease, which are caused by the filamentous fungus Magnaporthe Oryzae, therefore represent a major threat to global food stocks. This Review discusses how functional genomic approaches are shedding light on the mechanisms used by M. Oryzae during plant infection.
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Under pressure: investigating the biology of plant infection by Magnaporthe Oryzae
Nature Reviews Microbiology, 2009Co-Authors: Richard A. Wilson, Nicholas J. TalbotAbstract:Almost one-quarter of the calories consumed by the global human population is derived from rice. Epidemics of rice blast disease, which are caused by the filamentous fungus Magnaporthe Oryzae , therefore represent a major threat to global food stocks. This Review discusses how functional genomic approaches are shedding light on the mechanisms used by M. Oryzae during plant infection. Rice blast is caused by the ascomycete fungus Magnaporthe Oryzae and is the most serious disease of cultivated rice. The fungus is genetically tractable, has a sequenced genome and is experimentally amenable to study using functional genomics and cell biology. The fungus elaborates specialized cells called appressoria to infect plants. Appressorium development is cell cycle regulated and involves autophagic programmed cell death of the fungal spore. The cyclic AMP response pathway and the Pmk1 mitogen-activated protein kinase kinase pathway are necessary for appressorium development. Appressorium turgor generation involves accumulation of compatible solutes, including glycerol, which are derived from storage products in spores. Glycerol accumulation and melanization of the cell wall allow the deployment of sufficient turgor to breach the plant cuticle. The fungus spreads biotrophically in epidermal cells and might use protein effectors and/or secondary metabolites to suppress host defences. Disease symptoms involve necrosis of plant cells, which produces characteristic spreading lesions from which the fungus sporulates. Disease control by deployment of resistance genes, biotechnological approaches and development of new fungicides is an important aim of research on rice blast. The filamentous fungus Magnaporthe Oryzae causes rice blast, the most serious disease of cultivated rice. Cellular differentiation of M. Oryzae forms an infection structure called the appressorium, which generates enormous cellular turgor that is sufficient to rupture the plant cuticle. Here, we show how functional genomics approaches are providing new insight into the genetic control of plant infection by M. Oryzae . We also look ahead to the key questions that need to be addressed to provide a better understanding of the molecular processes that lead to plant disease and the prospects for sustainable control of rice blast.
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Under pressure: Investigating the biology of plant infection by Magnaporthe Oryzae
Nature reviews. Microbiology, 2009Co-Authors: Richard A. Wilson, Nicholas J. TalbotAbstract:The filamentous fungus Magnaporthe Oryzae causes rice blast, the most serious disease of cultivated rice. Cellular differentiation of M. Oryzae forms an infection structure called the appressorium, which generates enormous cellular turgor that is sufficient to rupture the plant cuticle. Here, we show how functional genomics approaches are providing new insight into the genetic control of plant infection by M. Oryzae. We also look ahead to the key questions that need to be addressed to provide a better understanding of the molecular processes that lead to plant disease and the prospects for sustainable control of rice blast.
