研究者詳細 - 鈴木　信弘

Omnipresence of Partitiviruses in Rice Aggregate Sheath Spot Symptom-Associated Fungal Isolates from Paddies in Thailand 査読

Sokty Neang, Santiti Bincader, Sansern Rangsuwan, Pisut Keawmanee, Soriya Rin, Lakha Salaipeth, Subha Das, Hideki Kondo, Nobuhiro Suzuki, Ikuo Sato, Daigo Takemoto, Chainarong Rattanakreetakul, Ratiya Pongpisutta, Masao Arakawa, Sotaro Chiba

Viruses 13 ( 11 ) 2269 - 2269 2021年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：MDPI AG

Partitiviruses are one of the most prevalent double-stranded RNA viruses that have been identified mostly in filamentous fungi and plants. Partitiviruses generally infect host fungi asymptomatically but infrequently exert significant effect(s) on morphology and virulence, thus being considered a potential source of biological control agents against pathogenic fungi. In this study, we performed a screening for mycoviruses of a collection of Thai isolates of rice fungal pathogen Rhizoctonia oryzae-sativae, a causal agent of rice aggregated sheath spot disease. As a result, 36% of tested isolates carried potentially viral double-stranded RNAs with sizes ranging from 2 to 3 kbp. By conventional cDNA library construction and RNA-seq, we determined six new alphapartitiviruses that infected three isolates: tentatively named Rhizoctonia oryzae-sativae partitivirus 1 to 6 (RosPV1-6). Furthermore, RT-PCR detection of each virus revealed their omnipresent nature in different R. oryzae-sativae isolates. Although virus-curing of basidiomycetous fungi is generally difficult, our repeated attempts successfully obtained virus-free (for RosPV1, RosPV2, and uncharacterized partitiviruses), isogenic strain of R. oryzae-sativae TSS190442. The virus-cured strain showed slightly faster colony growth on the synthetic media and severe symptom development on the rice sheath compared to its virus-infected counterpart. Overall, this study shed light on the distribution of partitiviruses in R. oryzae-sativae in a paddy environment and exemplified a virus-curing protocol that may be applicable for other basidiomycetous fungi.

DOI： 10.3390/v13112269

A new double-stranded rna mycovirus in cryphonectria naterciae is able to cross the species barrier and is deleterious to a new host 査読

Carolina Cornejo, Sakae Hisano, Helena Bragança, Nobuhiro Suzuki, Daniel Rigling

Journal of Fungi 7 ( 10 ) 861 2021年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

Cryphonectria is a fungal genus associated with economically significant disease of trees. Herein we characterized a novel double-stranded RNA virus from the fungal species Cryphonectria naterciae, a species unexplored as a virus host. De novo assembly of RNA-seq data and Sanger sequencing of RACE (rapid amplification of cDNA ends) clones gave the complete, non-segmented genome (10,164 bp) of the virus termed Cryphonectria naterciae fusagravirus (CnFGV1) that was phylogenetically placed within the previously proposed viral family Fusagraviridae. Of 31 fieldcollected strains of C. naterciae, 40% tested CnFGV1-positive. Cocultivation resulted in within-species transmission of CnFGV1 to virus-free strains of C. naterciae. Comparison of the mycelium phenotype and the growth rate of CnFGV1-infected and virus-free isogenic strains revealed frequent sectoring and growth reduction in C. naterciae upon virus infection. Co-culturing also led to cross-species transmission of CnFGV1 to Cryphonectria carpinicola and Cryphonectria radicalis, but not to Cryphonectria parasitica. The virus-infected C. naterciae and the experimentally infected Cryphonectria spp. readily transmitted CnFGV1 through asexual spores to the next generation. CnFGV1 strongly reduced conidiation and in some cases vegetative growth of C. carpinicola, which is involved in the European hornbeam disease. This study is the first report of a fusagravirus in the family Cryphonectriaceae and lays the groundwork for assessing a hypovirulence effect of CnFGV1 against the hornbeam decline in Europe.

DOI： 10.3390/jof7100861

Changes to virus taxonomy and to the International Code of Virus Classification and Nomenclature ratified by the International Committee on Taxonomy of Viruses (2021) 査読

Peter J. Walker, Stuart G. Siddell, Elliot J. Lefkowitz, Arcady R. Mushegian, Evelien M. Adriaenssens, Poliane Alfenas-Zerbini, Andrew J. Davison, Donald M. Dempsey, Bas E. Dutilh, María Laura García, Balázs Harrach, Robert L. Harrison, R. Curtis Hendrickson, Sandra Junglen, Nick J. Knowles, Mart Krupovic, Jens H. Kuhn, Amy J. Lambert, Małgorzata Łobocka, Max L. Nibert, Hanna M. Oksanen, Richard J. Orton, David L. Robertson, Luisa Rubino, Sead Sabanadzovic, Peter Simmonds, Donald B. Smith, Nobuhiro Suzuki, Koenraad Van Dooerslaer, Anne-Mieke Vandamme, Arvind Varsani, Francisco Murilo Zerbini

Archives of Virology 166 ( 9 ) 2633 - 2648 2021年9月

A second capsidless hadakavirus strain with 10 positive-sense single-stranded RNA genomic segments from Fusarium nygamai 査読

Haris Ahmed Khan, Yukiyo Sato, Hideki Kondo, Atif Jamal, Muhammad Faraz Bhatti, Nobuhiro Suzuki

Archives of Virology 166 2711 - 2722 2021年7月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media LLC

DOI： 10.1007/s00705-021-05176-x

その他リンク： https://link.springer.com/article/10.1007/s00705-021-05176-x/fulltext.html

In-tree behavior of diverse viruses harbored in the chestnut blight fungus, Cryphonectria parasitica 査読

Nobuhiro Suzuki, Carolina Cornejo, Annisa Aulia, Sabitree Shahi, Bradley I. Hillman, Daniel Rigling

Journal of Virology 95 ( 6 ) e01962-20 2021年3月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The ascomycete Cryphonectria parasitica causes destructive chestnut blight. Biological control of the fungus by virus infection (hypovirulence) has been shown to be an effective control strategy against chestnut blight in Europe. To provide biocontrol effects, viruses must be able to induce hypovirulence and spread efficiently in chestnut trees. Field studies using living trees to date have focused on a selected family of viruses called hypoviruses, especially prototypic hypovirus CHV1, but there are now known to be many other viruses that infect C. parasitica. Here, we tested seven different viruses for their hypovirulence induction, biocontrol potential, and transmission properties between two vegetatively compatible but molecularly distinguishable fungal strains in trees. The test included cytosolically and mitochondrially replicating viruses with positive-sense single-stranded RNA or double-stranded RNA genomes. The seven viruses showed different in planta behaviors and were classified into four groups. Group I, including CHV1, had great biocontrol potential and could protect trees by efficiently spreading and converting virulent to hypovirulent cankers in the trees. Group II could induce high levels of hypovirulence but showed much smaller biocontrol potential, likely because of inefficient virus transmission. Group III showed poor performance in hypovirulence induction and biocontrol, while efficiently being transmitted in the infected trees. Group IV could induce hypovirulence and spread efficiently but showed poor biocontrol potential. Nuclear and mitochondrial genotyping of fungal isolates obtained from the treated cankers confirmed virus transmission between the two fungal strains in most isolates. These results are discussed in view of dynamic interactions in the tripartite pathosystem. IMPORTANCE The ascomycete Cryphonectria parasitica causes destructive chestnut blight, which is controllable by hypovirulence-conferring viruses infecting the fungus. The tripartite chestnut/C. parasitica/virus pathosystem involves the dynamic interactions of their genetic elements, i.e., virus transmission and lateral transfer of nuclear and mitochondrial genomes between fungal strains via anastomosis occurring in trees. Here, we tested diverse RNA viruses for their hypovirulence induction, biocontrol potential, and transmission properties between two vegetatively compatible but molecularly distinguishable fungal strains in live chestnut trees. The tested viruses, which are different in genome type (single-stranded or double-stranded RNA) and organization, replication site (cytosol or mitochondria), virus form (encapsidated or capsidless) and/or symptomatology, have been unexplored in the aforementioned aspects under controlled conditions. This study showed intriguing different in-tree behaviors of the seven viruses and suggested that to exert significant biocontrol effects, viruses must be able to induce hypovirulence and spread efficiently in the fungus infecting the chestnut trees.

DOI： 10.1128/JVI.01962-20

Cryphonectria nitschkei chrysovirus 1 with unique molecular features and a very narrow host range 査読

Sabitree Shahi, Sotaro Chiba, Hideki Kondo, Nobuhiro Suzuki

Virology 554 55 - 65 2021年2月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Cryphonectria nitschkei chrysovirus 1 (CnCV1), was described earlier from an ascomycetous fungus, Cryphonectria nitschkei strain OB5/11, collected in Japan; its partial sequence was reported a decade ago. Complete sequencing of the four genomic dsRNA segments revealed molecular features similar to but distinct from previously reported members of the family Chrysoviridae. Unique features include the presence of a mini-cistron preceding the major large open reading frame in each genomic segment. Common features include the presence of CAA repeats in the 5′-untranslated regions and conserved terminal sequences. CnCV1-OB5/11 could be laterally transferred to C. nitschkei and its relatives C. radicalis and C. naterciae via coculturing, virion transfection and protoplast fusion, but not to fungal species other than the three species mentioned above, even within the genus Cryphonectria, suggesting a very narrow host range. Phenotypic comparison of a few sets of CnCV1-infected and -free isogenic strains showed symptomless infection in new hosts.

DOI： 10.1016/j.virol.2020.11.011

Identification of an RNA silencing suppressor encoded by a symptomless fungal hypovirus, Cryphonectria hypovirus 4 査読

Annisa Aulia, Kiwamu Hyodo, Sakae Hisano, Hideki Kondo, Bradley I. Hillman, Nobuhiro Suzuki

Biology 10 ( 2 ) 1 - 16 2021年2月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Previously, we have reported the ability of a symptomless hypovirus Cryphonectria hypovirus 4 (CHV4) of the chestnut blight fungus to facilitate stable infection by a co-infecting mycoreovirus 2 (MyRV2)—likely through the inhibitory effect of CHV4 on RNA silencing (Aulia et al., Virology, 2019). In this study, the N-terminal portion of the CHV4 polyprotein, termed p24, is identified as an autocatalytic protease capable of suppressing host antiviral RNA silencing. Using a bacterial expression system, CHV4 p24 is shown to cleave autocatalytically at the di-glycine peptide (Gly214-Gly215) of the polyprotein through its protease activity. Transgenic expression of CHV4 p24 in Cryphonectria parasitica suppresses the induction of one of the key genes of the antiviral RNA silencing, dicer-like 2, and stabilizes the infection of RNA silencing-susceptible virus MyRV2. This study shows functional similarity between CHV4 p24 and its homolog p29, encoded by the symptomatic prototype hypovirus CHV1.

DOI： 10.3390/biology10020100

A moderate level of hypovirulence conferred by a hypovirus in the avocado white root rot fungus, Rosellinia necatrix 査読

Juan M. Arjona-López, Paul Telengech, Nobuhiro Suzuki, Carlos J. López-Herrera

Fungal Biology 125 ( 1 ) 69 - 76 2021年1月

記述言語：英語掲載種別：研究論文（学術雑誌）

Two isolates of Rosellinia necatrix (Rn118-8 and Rn480) have previously obtained from diseased avocado trees in commercial orchards of the coastal area in southern Spain. Rn118-8 and Rn480 have weak virulence on avocado plants, and are infected by R. necatrix hypovirus 2 (RnHV2). In this work, the possible biological effects of the hypovirus on R. necatrix were tested. First, RnHV2 was transmitted from each of Rn118-8 and Rn480 to a highly virulent, RnHV2-free isolate of R. necatrix (Rn400) through hyphal anastomosis, using zinc compounds which attenuate the mycelial incompatibility reactions and allow for horizontal virus transfer between vegetatively incompatible fungal strains. Next, we carried out an analysis of growth rate in vitro and a virulence test of these newly infected strains in avocado plants. We obtained five strains of Rn400 infected by RnHV2 after horizontal transmission, and showed some of them to have lower colony growth in vitro and lower virulence on avocado plants compared with virus-free Rn400. These results suggest that R. necatrix isolates infected by RnHV2 could be used as novel virocontrol agents to combat avocado white root rot.

DOI： 10.1016/j.funbio.2020.10.007

Biochemical characterization of the dicing activity of Dicer-like 2 in the model filamentous fungus Neurospora crassa 査読

Midori Tabara, Hisashi Koiwa, Nobuhiro Suzuki, Toshiyuki Fukuhara

Fungal Genetics and Biology 146 103488 2021年1月

記述言語：英語掲載種別：研究論文（学術雑誌）

Dicing of double-stranded RNA (dsRNA) into small RNA is an essential process to trigger transcriptional and post-transcriptional gene silencing. Using cell-free extracts of the model filamentous fungus Neurospora crassa, we successfully detected the dicing activity of one of two N. crassa Dicers NcDCL2. The predominant 23-nucleotide (nt) cleavage product was always detected from 30-nt to 130-nt dsRNA substrates, and additional products of approximately 18 to 28 nt were occasionally produced. The enzymatic properties of NcDCL2 are different from those of insect and plant small interfering RNA (siRNA)-producing Dicers, Drosophila melanogaster Dicer-2 and Arabidopsis thaliana DCL3 and DCL4 (AtDCL3 and AtDCL4). Whereas AtDCL3 and AtDCL4 preferentially cleave short and long dsRNAs, respectively, NcDCL2 cleaved both short and long dsRNAs. These results suggest that N. crassa has a single siRNA-producing Dicer NcDCL2, which is a prototype of plant siRNA-producing Dicers with distinct functions in diverse RNA silencing pathways. The dicing assay reported here is convenient to detect and biochemically characterize the dicing activities of both plant and fungal Dicers, and is likely applicable to other organisms.

DOI： 10.1016/j.fgb.2020.103488

Identification of a Novel Quinvirus in the Family Betaflexiviridae That Infects Winter Wheat. 査読国際誌

Hideki Kondo, Naoto Yoshida, Miki Fujita, Kazuyuki Maruyama, Kiwamu Hyodo, Hiroshi Hisano, Tetsuo Tamada, Ida Bagus Andika, Nobuhiro Suzuki

Frontiers in microbiology 12 715545 2021年

記述言語：英語掲載種別：研究論文（学術雑誌）

Yellow mosaic disease in winter wheat is usually attributed to the infection by bymoviruses or furoviruses; however, there is still limited information on whether other viral agents are also associated with this disease. To investigate the wheat viromes associated with yellow mosaic disease, we carried out de novo RNA sequencing (RNA-seq) analyses of symptomatic and asymptomatic wheat-leaf samples obtained from a field in Hokkaido, Japan, in 2018 and 2019. The analyses revealed the infection by a novel betaflexivirus, which tentatively named wheat virus Q (WVQ), together with wheat yellow mosaic virus (WYMV, a bymovirus) and northern cereal mosaic virus (a cytorhabdovirus). Basic local alignment search tool (BLAST) analyses showed that the WVQ strains (of which there are at least three) were related to the members of the genus Foveavirus in the subfamily Quinvirinae (family Betaflexiviridae). In the phylogenetic tree, they form a clade distant from that of the foveaviruses, suggesting that WVQ is a member of a novel genus in the Quinvirinae. Laboratory tests confirmed that WVQ, like WYMV, is potentially transmitted through the soil to wheat plants. WVQ was also found to infect rye plants grown in the same field. Moreover, WVQ-derived small interfering RNAs accumulated in the infected wheat plants, indicating that WVQ infection induces antiviral RNA silencing responses. Given its common coexistence with WYMV, the impact of WVQ infection on yellow mosaic disease in the field warrants detailed investigation.

DOI： 10.3389/fmicb.2021.715545

Molecular Characterization of a Novel Polymycovirus From Penicillium janthinellum With a Focus on Its Genome-Associated PASrp 査読

Yukiyo Sato, Atif Jamal, Hideki Kondo, Nobuhiro Suzuki

Frontiers in Microbiology 11 e0045-20 2020年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The genus Polymycovirus of the family Polymycoviridae accommodates fungal RNA viruses with different genomic segment numbers (four, five, or eight). It is suggested that four members form no true capsids and one forms filamentous virus particles enclosing double-stranded RNA (dsRNA). In both cases, viral dsRNA is associated with a viral protein termed “proline-alanine-serine-rich protein” (PASrp). These forms are assumed to be the infectious entity. However, the detailed molecular characteristics of PASrps remain unclear. Here, we identified a novel five-segmented polymycovirus, Penicillium janthinellum polymycovirus 1 (PjPmV1), and characterized its purified fraction form in detail. The PjPmV1 had five dsRNA segments associated with PASrp. Density gradient ultracentrifugation of the PASrp-associated PjPmV1 dsRNA revealed its uneven structure and a broad fractionation profile distinct from that of typical encapsidated viruses. Moreover, PjPmV1-PASrp interacted in vitro with various nucleic acids in a sequence-non-specific manner. These PjPmV1 features are discussed in view of the diversification of genomic segment numbers of the genus Polymycovirus.

DOI： 10.3389/fmicb.2020.592789

Coinfection of Rosellinia necatrix by a partitivirus and a virga-like virus is associated with hypovirulence 査読

Juan M. Arjona-López, Paul Telengech, Nobuhiro Suzuki, Carlos J. López-Herrera

European Journal of Plant Pathology 158 ( 1 ) 111 - 119 2020年9月

記述言語：英語掲載種別：研究論文（学術雑誌）

Many Mediteranean isolates of Rosellinia necatrix, causing root rot in avocado, have previously been screened for viruses. Among them is isolate Rn459 that has been shown to be infected by at least three viruses such as Rosellinia necatrix partitivirus 10 (RnPV10), Rosellinia necatrix hypovirus 2 (RnHV2), Rosellinia necatrix fusagravirus 1 (RnFGV1), and Rosellinia necatrix virga-like virus (RnVLV). Here, we attempted to eliminate the viruses by hyphal tip cultures to examine their effect on colony growth in vitro and virulence on avocado plants. The obtained fungal strain termed, Rn459_PV10F/VLVF, which was confirmed to be cured of RnPV10 and RnVLV, but still retaining RnHV2, manifested a phenotype different from the original Rn459. Colony growth comparison showed that Rn459_PV10F/VLVF grew faster than the original Rn459 isolate and the virulence on avocado plants of this Rn459_PV10F/VLVF strain was higher than the original Rn459 strain. These combined results suggest that RnPV10 and RnVLV, alone or together, contribute to confer hypovirulence on the R. necatrix isolates.

DOI： 10.1007/s10658-020-02058-x

Dicer monitoring in a model filamentous fungus host, Cryphonectria parasitica 査読

Annisa Aulia, Midori Tabara, Paul Telengech, Toshiyuki Fukuhara, Nobuhiro Suzuki

Current Research in Virological Science 100001 - 100001 2020年7月

Diverse Partitiviruses From the Phytopathogenic Fungus, Rosellinia necatrix 査読

Paul Telengech, Sakae Hisano, Cyrus Mugambi, Kiwamu Hyodo, Juan Manuel Arjona-López, Carlos José López-Herrera, Satoko Kanematsu, Hideki Kondo, Nobuhiro Suzuki

Frontiers in Microbiology 11 1064 2020年6月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Partitiviruses (dsRNA viruses, family Partitiviridae) are ubiquitously detected in plants and fungi. Although previous surveys suggested their omnipresence in the white root rot fungus, Rosellinia necatrix, only a few of them have been molecularly and biologically characterized thus far. We report the characterization of a total of 20 partitiviruses from 16 R. necatrix strains belonging to 15 new species, for which “Rosellinia necatrix partitivirus 11–Rosellinia necatrix partitivirus 25” were proposed, and 5 previously reported species. The newly identified partitiviruses have been taxonomically placed in two genera, Alphapartitivirus, and Betapartitivirus. Some partitiviruses were transfected into reference strains of the natural host, R. necatrix, and an experimental host, Cryphonectria parasitica, using purified virions. A comparative analysis of resultant transfectants revealed interesting differences and similarities between the RNA accumulation and symptom induction patterns of R. necatrix and C. parasitica. Other interesting findings include the identification of a probable reassortment event and a quintuple partitivirus infection of a single fungal strain. These combined results provide a foundation for further studies aimed at elucidating mechanisms that underly the differences observed.

DOI： 10.3389/fmicb.2020.01064