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Çelik A, Çakar D, Derviş S, Morca AF, Akıllı Şimşek S, Romon-Ochoa P, Özer G. New Detection Methods for Cryphonectria Hypovirus 1 (CHV1) through SYBR Green-Based Real-Time PCR and Loop-Mediated Isothermal Amplification (LAMP). Viruses 2024; 16:1203. [PMID: 39205177 PMCID: PMC11360611 DOI: 10.3390/v16081203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2024] [Revised: 07/16/2024] [Accepted: 07/24/2024] [Indexed: 09/04/2024] Open
Abstract
Some mycoviruses can be considered as effective biocontrol agents, mitigating the impact of phytopathogenic fungi and consequently reducing disease outbreaks while promoting plant health. Cryphonectria parasitica, the causal agent of chestnut blight and a highly destructive pathogen, experienced a notable decrease in its virulence with the identification of cryphonectria hypovirus 1 (CHV1), a naturally occurring biocontrol agent. In this study, two innovative diagnostic protocols designed for the accurate and efficient detection of CHV1 are introduced. The ORF A and ORF B regions of CHV1 are targeted by these techniques, which employ colorimetric loop-mediated isothermal amplification (LAMP) with 2 Colorimetric LAMP Master Mix and real-time quantitative PCR (qPCR) with SYBR Green chemistry, respectively. The LAMP assay presents a discernible color transition, changing from pink to yellow after a 35 min incubation period. Comparative analysis, when assessed against two established reverse transcription-PCR (RT-PCR) techniques, reveals a significant enhancement in sensitivity for both the LAMP approach, which offers a tenfold increase, and the qPCR method, which showcases a remarkable 100-fold sensitivity improvement. Throughout the comparison phase, it was evident that the RT-PCR, LAMP, and qPCR procedures displayed superior performance compared to the Bavendamm test, relying on phenol oxidase activity, effectively distinguishing hypovirulent strains. Consequently, this study introduces two pioneer diagnostic assays for highly sensitive CHV1 detection, representing a substantial advancement in the realm of CHV1 surveillance techniques. These methodologies hold significant promise for enhancing research endeavors in the domain of the biological control of C. parasitica.
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Affiliation(s)
- Ali Çelik
- Department of Plant Protection, Faculty of Agriculture, Bolu Abant İzzet Baysal University, Bolu 14030, Türkiye
| | - Deniz Çakar
- Central Research Laboratory Application and Research Center, Çankırı Karatekin University, Çankırı 18100, Türkiye
| | - Sibel Derviş
- Department of Plant Protection, Faculty of Kızıltepe Agricultural Sciences and Technologies, Mardin Artuklu University, Mardin 47000, Türkiye
- Department of Plant and Animal Production, Vocational School of Kızıltepe, Mardin Artuklu University, Mardin 47000, Türkiye
| | - Ali Ferhan Morca
- Directorate of Plant Protection Central Research Institute, Gayret Mah. Fatih Sultan Mehmet Bulv., Yenimahalle, Ankara 06172, Türkiye
| | - Seçil Akıllı Şimşek
- Department of Biology, Faculty of Sciences, Çankırı Karatekin University, Çankırı 18100, Türkiye
| | - Pedro Romon-Ochoa
- Forest Research, Plant Pathology Department, Alice Holt Research Station, Farnham GU10 4LH, UK
| | - Göksel Özer
- Department of Plant Protection, Faculty of Agriculture, Bolu Abant İzzet Baysal University, Bolu 14030, Türkiye
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2
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Romon-Ochoa P, Samal P, Gorton C, Lewis A, Chitty R, Eacock A, Krzywinska E, Crampton M, Pérez-Sierra A, Biddle M, Jones B, Ward L. Cryphonectria parasitica Detections in England, Jersey, and Guernsey during 2020-2023 Reveal Newly Affected Areas and Infections by the CHV1 Mycovirus. J Fungi (Basel) 2023; 9:1036. [PMID: 37888292 PMCID: PMC10607933 DOI: 10.3390/jof9101036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 10/08/2023] [Accepted: 10/09/2023] [Indexed: 10/28/2023] Open
Abstract
In England, Cryphonectria parasitica was detected for the first time in 2011 in a nursery and in 2016 in the wider environment. Surveys between 2017 and 2020 identified the disease at different sites in Berkshire, Buckinghamshire, Cornwall, Derbyshire, Devon, Dorset, London, West Sussex, and the island of Jersey, while the present study comprises the results of the 2020-2023 survey with findings in Derbyshire, Devon, Kent, Nottinghamshire, Herefordshire, Leicestershire, London, West Sussex, and the islands of Jersey and Guernsey. A total of 226 suspected samples were collected from 72 surveyed sites, as far north as Edinburgh and as far west as Plymouth (both of which were negative), and 112 samples tested positive by real-time PCR and isolation from 35 sites. The 112 isolates were tested for the vegetative compatibility group (VCG), mating type, and Cryphonectria hypovirus 1 (CHV1). Twelve VCGs were identified, with two of them (EU-5 and EU-22) being the first records in the UK. Both mating types were present (37% MAT-1 and 63% MAT-2), but only one mating type was present per site and VCG, and perithecia were never observed. Cryphonectria hypovirus 1 (CHV1), consistently subtype-I haplotype E-5, was detected in three isolates at a low concentration (5.9, 21.1, and 33.0 ng/µL) from locations in London, Nottinghamshire, and Devon.
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Affiliation(s)
- Pedro Romon-Ochoa
- Forest Research, Plant Pathology Department, Alice Holt Research Station, Farnham, Surrey GU10 4LH, UK; (P.S.); (M.B.); (L.W.)
| | - Pankajini Samal
- Forest Research, Plant Pathology Department, Alice Holt Research Station, Farnham, Surrey GU10 4LH, UK; (P.S.); (M.B.); (L.W.)
| | - Caroline Gorton
- Forest Research, THDAS-Tree Health Diagnostics and Advisory Service, Alice Holt Research Station, Farnham, Surrey GU10 4LH, UK; (C.G.); (A.L.); (R.C.); (A.E.); (E.K.); (M.C.); (A.P.-S.)
| | - Alex Lewis
- Forest Research, THDAS-Tree Health Diagnostics and Advisory Service, Alice Holt Research Station, Farnham, Surrey GU10 4LH, UK; (C.G.); (A.L.); (R.C.); (A.E.); (E.K.); (M.C.); (A.P.-S.)
| | - Ruth Chitty
- Forest Research, THDAS-Tree Health Diagnostics and Advisory Service, Alice Holt Research Station, Farnham, Surrey GU10 4LH, UK; (C.G.); (A.L.); (R.C.); (A.E.); (E.K.); (M.C.); (A.P.-S.)
| | - Amy Eacock
- Forest Research, THDAS-Tree Health Diagnostics and Advisory Service, Alice Holt Research Station, Farnham, Surrey GU10 4LH, UK; (C.G.); (A.L.); (R.C.); (A.E.); (E.K.); (M.C.); (A.P.-S.)
| | - Elzbieta Krzywinska
- Forest Research, THDAS-Tree Health Diagnostics and Advisory Service, Alice Holt Research Station, Farnham, Surrey GU10 4LH, UK; (C.G.); (A.L.); (R.C.); (A.E.); (E.K.); (M.C.); (A.P.-S.)
| | - Michael Crampton
- Forest Research, THDAS-Tree Health Diagnostics and Advisory Service, Alice Holt Research Station, Farnham, Surrey GU10 4LH, UK; (C.G.); (A.L.); (R.C.); (A.E.); (E.K.); (M.C.); (A.P.-S.)
| | - Ana Pérez-Sierra
- Forest Research, THDAS-Tree Health Diagnostics and Advisory Service, Alice Holt Research Station, Farnham, Surrey GU10 4LH, UK; (C.G.); (A.L.); (R.C.); (A.E.); (E.K.); (M.C.); (A.P.-S.)
| | - Mick Biddle
- Forest Research, Plant Pathology Department, Alice Holt Research Station, Farnham, Surrey GU10 4LH, UK; (P.S.); (M.B.); (L.W.)
| | - Ben Jones
- Forestry Commission, 620 Bristol Business Park, Bristol BS16 1EJ, UK;
| | - Lisa Ward
- Forest Research, Plant Pathology Department, Alice Holt Research Station, Farnham, Surrey GU10 4LH, UK; (P.S.); (M.B.); (L.W.)
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3
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Cornejo C, Otani T, Suzuki N, Beenken L. Cryphonectria carpinicola discovered in Japan: first report of the sexual state on Carpinus tree. MYCOSCIENCE 2023; 64:123-127. [PMID: 37936945 PMCID: PMC10627740 DOI: 10.47371/mycosci.2023.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 06/15/2023] [Accepted: 07/12/2023] [Indexed: 11/09/2023]
Abstract
Cryphonectria carpinicola is an ascomycetous fungus that has been regularly found in its asexual form on European hornbeam (Carpinus betulus) in Europe over the past two decades. Here we describe the discovery of C. carpinicola in Japan and report for the first time its sexual state on Carpinus species. No symptomatic trees were observed, but stromata were found saprotrophically on broken branches of Carpinus species on the forest floor. The sexual structures of C. carpinicola resembled that of other Cryphonectria species and strongly resembled those of the closely related species C. radicalis. A phylogenetic tree based on the internal transcribed spacer sequences showed monophyly for the Japanese and European isolates of C. carpinicola. Further studies on the distribution and host range of C. carpinicola in Japan and on the life history strategies of this fungus are needed.
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Affiliation(s)
- Carolina Cornejo
- Swiss Federal
Research Institute WSL, Forest Health and Biotic
Interactions
| | - Tatsuya Otani
- Shikoku
Research Center, Forestry and Forest Products Research
Institute
| | - Nobuhiro Suzuki
- Institute of
Plant Science and Resources, Okayama University
| | - Ludwig Beenken
- Swiss Federal
Research Institute WSL, Forest Health and Biotic
Interactions
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4
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Romon-Ochoa P, Smith O, Lewis A, Kupper Q, Shamsi W, Rigling D, Pérez-Sierra A, Ward L. Temperature Effects on the Cryphonectria hypovirus 1 Accumulation and Recovery within Its Fungal Host, the Chestnut Blight Pathogen Cryphonectria parasitica. Viruses 2023; 15:1260. [PMID: 37376560 DOI: 10.3390/v15061260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 05/24/2023] [Accepted: 05/25/2023] [Indexed: 06/29/2023] Open
Abstract
Biological control of Cryphonectria parasitica fungus, the causal agent of chestnut blight, by virus infection (hypovirulence) is an effective control strategy against chestnut blight in Europe and some parts of North America. The most studied mycovirus is the Cryphonectria hypovirus 1 (CHV1) type species of the Hypoviridae family. In this study, the CHV1 virus was studied within some highly infected British isolates of Cryphonectria parasitica, gained in the past through co-culture transmissions. The effects of six temperatures (5-30 °C, in 5 °C steps) on six infected isolates (three with viral strain E-5, and other three with viral strain L-18) and their respective negative non-infected controls, three isogenic virulent fungal isolates, were examined. Experiments were performed with the nine isolate types with three replicates on potato dextrose agar (PDA) with cellophane sheets per isolate and temperature. A recently developed rapid, specific, quantitative reverse transcription PCR (RT-qPCR) screening method was used. This enabled quantifying the concentration (nanograms per microliter or copy numbers) of the virus within each isolate repetition. The presence of the virus had a significant negative effect between 20 and 25 °C on the C. parasitica growth rate, which was anyway highly influenced by and positively correlated with the temperature. The temperature clearly determined the virus accumulation and its recovery from cold or heat, and the virus optimum temperature was estimated at 15-25 °C.
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Affiliation(s)
- Pedro Romon-Ochoa
- Forest Research, Plant Pathology Department, Alice Holt Research Station, Surrey GU104LH, UK
| | - Olivia Smith
- Forest Research, Plant Pathology Department, Alice Holt Research Station, Surrey GU104LH, UK
| | - Alex Lewis
- Forest Research, Tree Health Diagnostics and Advisory Service (THDAS), Alice Holt, Surrey GU104LH, UK
| | - Quirin Kupper
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Wajeeha Shamsi
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Daniel Rigling
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Ana Pérez-Sierra
- Forest Research, Tree Health Diagnostics and Advisory Service (THDAS), Alice Holt, Surrey GU104LH, UK
| | - Lisa Ward
- Forest Research, Plant Pathology Department, Alice Holt Research Station, Surrey GU104LH, UK
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Canker Development and Biocontrol Potential of CHV-1 Infected English Isolates of Cryphonectria parasitica Is Dependent on the Virus Concentration and the Compatibility of the Fungal Inoculums. Viruses 2022; 14:v14122678. [PMID: 36560682 PMCID: PMC9785502 DOI: 10.3390/v14122678] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 11/23/2022] [Accepted: 11/26/2022] [Indexed: 12/05/2022] Open
Abstract
Biological control of Cryphonectria parasitica fungus, causal agent of chestnut blight, by virus infection (hypovirulence) has been shown to be an effective control strategy against chestnut blight in Europe and some parts of North America. The most studied mycovirus is the Cryphonectria hypovirus 1 (CHV-1) type species of the Hypoviridae family. To efficiently provide biocontrol, the virus must be able to induce hypovirulence in its fungal host in chestnut trees. Here, two different CHV-1 subtype I virus strains (E-5 and L-18), gained by transmissions, were tested for their hypovirulence induction, biocontrol potential, and transmission between vegetatively compatible (VCG) and incompatible fungal isolate groups in sweet chestnut seedlings and branches. Both strains of CHV-1 showed great biocontrol potential and could protect trees by efficiently transmitting CHV-1 by hyphal anastomosis between fungal isolates of the same VCG and converting virulent to hypovirulent cankers. The hypovirulent effect was positively correlated with the virus concentration, tested by four different reverse-transcription PCRs, two end-point and two real-time methods, one of which represents a newly developed real-time PCR for the detection and quantification of CHV-1.
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6
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Das S, Hisano S, Eusebio-Cope A, Kondo H, Suzuki N. A Transfectable Fusagravirus from a Japanese Strain of Cryphonectria carpinicola with Spherical Particles. Viruses 2022; 14:v14081722. [PMID: 36016344 PMCID: PMC9413294 DOI: 10.3390/v14081722] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/03/2022] [Accepted: 08/03/2022] [Indexed: 02/05/2023] Open
Abstract
A novel dsRNA virus (Cryphonectria carpinicola fusagravirus 1, CcFGV1), isolated from a Japanese strain (JS13) of Cryphonectria carpinicola, was thoroughly characterized. The biological comparison of a set of isogenic CcFGV1-infected and -free (JS13VF) strains indicated asymptomatic infection by CcFGV1. The sequence analysis showed that the virus has a two open reading frame (ORF) genome of 9.6 kbp with the RNA-directed RNA polymerase domain encoded by ORF2. The N-terminal sequencing and peptide mass fingerprinting showed an N-terminally processed or degraded product (150 kDa) of the 5′-proximal ORF1-encoded protein (1462 amino acids) to make up the CcFGV1 spherical particles of ~40 nm in diameter. Interestingly, a portion of CcFGV1 dsRNA co-fractionated with a host protein of 70 kDa. The purified CcFGV1 particles were used to transfect protoplasts of JS13VF as well as the standard strain of an experimental model filamentous fungal host Cryphonectria parasitica. CcFGV1 was confirmed to be associated with asymptomatic infection of both fungi. RNA silencing was shown to target the virus in C. parasitica, resulting in reduced CcFGV1 accumulation by comparing the CcFGV1 content between RNA silencing-competent and -deficient strains. These results indicate the transfectability of spherical particles of a fusagravirus associated with asymptomatic infection.
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Xu G, Zhang X, Liang X, Chen D, Xie C, Kang Z, Zheng L. A novel hexa-segmented dsRNA mycovirus confers hypovirulence in the phytopathogenic fungus Diaporthe pseudophoenicicola. Environ Microbiol 2022; 24:4274-4284. [PMID: 35315558 DOI: 10.1111/1462-2920.15963] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 03/02/2022] [Indexed: 11/28/2022]
Abstract
A novel hexa-segmented double-stranded RNA (dsRNA) mycovirus was isolated and characterized from the filamentous phytopathogenic fungus Diaporthe pseudophoenicicola, and was named Diaporthe pseudophoenicicola chrysovirus 1 (DpCV1). The full-length cDNAs of dsRNA1-6 were 3335, 3030, 3039, 2980, 963, and 780 bp, respectively. Sequence analysis indicated the presence of nine open reading frames (ORFs) in the DpCV1 genome. ORF1 in dsRNA1 putatively encoded the RNA-dependent RNA polymerase (RdRp), and ORF3 in dsRNA2 encoded a capsid protein (CP). The seven remaining ORFs, ORF2 in dsRNA2, ORF4 in dsRNA3, ORF6, 7 in dsRNA4, ORF8 in dsRNA5, and ORF9 in dsRNA6, encoded proteins with unknown functions. Phylogenetic analysis revealed that DpCV1 is closely related to members of the cluster I group within the family Chrysoviridae but formed a separate clade. Importantly, all the six segments of DpCV1 were cured successfully through single spore isolation to obtain the isogenic virus-free strains. DpCV1 can confer hypovirulence to the fungal host of Diaporthe pseudophoenicicola. Compared with the virus-free strain, WC02 harboring the DpCV1 is more sensitive to fungicide prochloraz. Furthermore, the cell wall of DpCV1 infected strain was loose and enlarged. This is the first report of a hexa-segmented tentative chrysovirus in D. pseudophoenicicola. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Gang Xu
- Key Laboratory of Green Prevention and Control of Tropical Plant Disease and Pests, Ministry of Education and School of Plant Protection, Hainan University, Haikou, Hainan, 570228, China
| | - Xinchun Zhang
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou, Hainan, 571101, China
| | - Xiaofei Liang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Daipeng Chen
- Key Laboratory of Green Prevention and Control of Tropical Plant Disease and Pests, Ministry of Education and School of Plant Protection, Hainan University, Haikou, Hainan, 570228, China
| | - Changping Xie
- Key Laboratory of Green Prevention and Control of Tropical Plant Disease and Pests, Ministry of Education and School of Plant Protection, Hainan University, Haikou, Hainan, 570228, China
| | - Zhensheng Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Li Zheng
- Key Laboratory of Green Prevention and Control of Tropical Plant Disease and Pests, Ministry of Education and School of Plant Protection, Hainan University, Haikou, Hainan, 570228, China
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Sato Y, Shahi S, Telengech P, Hisano S, Cornejo C, Rigling D, Kondo H, Suzuki N. A new tetra-segmented splipalmivirus with divided RdRP domains from Cryphonectria naterciae, a fungus found on chestnut and cork oak trees in Europe. Virus Res 2022; 307:198606. [PMID: 34688782 DOI: 10.1016/j.virusres.2021.198606] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 10/09/2021] [Accepted: 10/12/2021] [Indexed: 01/01/2023]
Abstract
Positive-sense (+), single-stranded (ss) RNA viruses with divided RNA-dependent RNA polymerase (RdRP) domains have been reported from diverse filamentous ascomycetes since 2020. These viruses are termed splipalmiviruses or polynarnaviruses and have been characterized largely at the sequence level, but ill-defined biologically. Cryphonectria naterciae, from which only one virus has been reported, is an ascomycetous fungus potentially plant-pathogenic to chestnut and oak trees. We molecularly characterized multiple viruses in a single Portuguese isolate (C0614) of C. naterciae, taking a metatranscriptomic and conventional double-stranded RNA approach. Among them are a novel splipalmivirus (Cryphonectria naterciae splipalmivirus 1, CnSpV1) and a novel fusagravirus (Cryphonectria naterciae fusagravirus 1, CnFGV1). This study focused on the former virus. CnSpV1 has a tetra-segmented, (+)ssRNA genome (RNA1 to RNA4). As observed for other splipalmiviruses reported in 2020 and 2021, the RdRP domain is separately encoded by RNA1 (motifs F, A and B) and RNA2 (motifs C and D). A hypothetical protein encoded by the 5'-proximal open reading frame of RNA3 shows similarity to a counterpart conserved in some splipalmiviruses. The other RNA3-encoded protein and RNA4-encoded protein show no similarity with known proteins in a blastp search. The tetra-segment nature was confirmed by the conserved terminal sequences of the four CnSpV1 segments (RNA1 to RNA4) and their 100% coexistence in over 100 single conidial isolates tested. The experimental introduction of CnSpV1 along with CnFGV1 into a virus free strain C0754 of C. naterciae vegetatively incompatible with C0614 resulted in no phenotypic alteration, suggesting asymptomatic infection. The protoplast fusion assay indicates a considerably narrow host range of CnSpV1, restricted to the species C. naterciae and C. carpinicola. This study contributes to better understanding of the molecular and biological properties of this unique group of viruses.
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Affiliation(s)
- Yukiyo Sato
- Institute of Plant Science and Resources, Okayama University, Kurashiki, 710-0046, Japan
| | - Sabitree Shahi
- Institute of Plant Science and Resources, Okayama University, Kurashiki, 710-0046, Japan
| | - Paul Telengech
- Institute of Plant Science and Resources, Okayama University, Kurashiki, 710-0046, Japan
| | - Sakae Hisano
- Institute of Plant Science and Resources, Okayama University, Kurashiki, 710-0046, Japan
| | - Carolina Cornejo
- Swiss Federal Research Institute WSL, Forest Health & Biotic Interactions, Zuercherstrasse 111, CH-8903 Birmensdorf
| | - Daniel Rigling
- Swiss Federal Research Institute WSL, Forest Health & Biotic Interactions, Zuercherstrasse 111, CH-8903 Birmensdorf
| | - Hideki Kondo
- Institute of Plant Science and Resources, Okayama University, Kurashiki, 710-0046, Japan
| | - Nobuhiro Suzuki
- Institute of Plant Science and Resources, Okayama University, Kurashiki, 710-0046, Japan.
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9
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A New Double-Stranded RNA Mycovirus in Cryphonectria naterciae Is Able to Cross the Species Barrier and Is Deleterious to a New Host. J Fungi (Basel) 2021; 7:jof7100861. [PMID: 34682282 PMCID: PMC8538617 DOI: 10.3390/jof7100861] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/07/2021] [Accepted: 10/12/2021] [Indexed: 12/25/2022] Open
Abstract
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 field-collected 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.
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10
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Shahi S, Chiba S, Kondo H, Suzuki N. Cryphonectria nitschkei chrysovirus 1 with unique molecular features and a very narrow host range. Virology 2020; 554:55-65. [PMID: 33383414 DOI: 10.1016/j.virol.2020.11.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 11/21/2020] [Accepted: 11/23/2020] [Indexed: 12/20/2022]
Abstract
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.
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Affiliation(s)
- Sabitree Shahi
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, 710-0046, Japan
| | - Sotaro Chiba
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Hideki Kondo
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, 710-0046, Japan
| | - Nobuhiro Suzuki
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, 710-0046, Japan.
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11
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Romon-Ochoa P, Gorton C, Lewis A, van der Linde S, Webber J, Pérez-Sierra A. Hypovirulent effect of the Cryphonectria hypovirus 1 in British isolates of Cryphonectria parasitica. PEST MANAGEMENT SCIENCE 2020; 76:1333-1343. [PMID: 31603609 DOI: 10.1002/ps.5644] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 10/01/2019] [Accepted: 10/02/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND Chestnut blight, caused by Cryphonectria parasitica, is controlled in many European countries by the naturally occurring mycovirus Cryphonectria hypovirus 1 (CHV-1). During surveys of recently identified chestnut blight outbreak in England, CHV-1 was detected in several individuals of the pathogen isolated from affected trees. We investigated two of these CHV-1-infected isolates (L-6 and Db-1) as potential biocontrol agents for deployment in the UK comparing their virulence against virus-free (M1275) and hypovirulent (M784) European isolates by inoculating sweet chestnut seedlings. RESULTS Both the European CHV-1 M784 hypovirulent isolate and UK L-6 isolate formed significantly smaller lesions in sweet chestnut seedling bark than the other three isolates (Db-1, and virulent isolates FTC121 and M1275). The highest virus concentration was detected in isolate M784, followed by L-6, with the lowest concentration in isolate Db-1. White colony colouration indicative of hypovirulence was common in colonies re-isolated from smaller lesions, and the same isolates also tended to be slower growing in culture, have a higher virus concentration, and caused less epicormic growth and fewer stromata to be present in plants. L-6 and Db-1 virus sequences, respectively, matched the virus haplotype E-5 detected previously in Switzerland and a mutation of the same subtype I haplotype. CONCLUSION Isolate L-6 could potentially act as biocontrol for chestnut blight outbreaks in the UK but further laboratory and field experiments are needed. © 2019 Crown copyright. Pest Management Science © 2019 Society of Chemical Industry.
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Affiliation(s)
- Pedro Romon-Ochoa
- Forest Research, Tree Health Diagnostics and Advisory Service (THDAS), Farnham, UK
| | - Caroline Gorton
- Forest Research, Tree Health Diagnostics and Advisory Service (THDAS), Farnham, UK
| | - Alex Lewis
- Forest Research, Tree Health Diagnostics and Advisory Service (THDAS), Farnham, UK
| | - Sietse van der Linde
- Forest Research, Tree Health Diagnostics and Advisory Service (THDAS), Farnham, UK
| | - Joan Webber
- Forest Research, Tree Health Diagnostics and Advisory Service (THDAS), Farnham, UK
| | - Ana Pérez-Sierra
- Forest Research, Tree Health Diagnostics and Advisory Service (THDAS), Farnham, UK
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Krstin L, Katanić Z, Repar J, Ježić M, Kobaš A, Ćurković-Perica M. Genetic Diversity of Cryphonectria hypovirus 1, a Biocontrol Agent of Chestnut Blight, in Croatia and Slovenia. MICROBIAL ECOLOGY 2020; 79:148-163. [PMID: 31053974 DOI: 10.1007/s00248-019-01377-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 04/03/2019] [Indexed: 06/09/2023]
Abstract
Transmissible hypovirulence associated with Cryphonectria hypovirus 1 (CHV1) has been used for biological control of chestnut blight, devastating disease of chestnut caused by the fungus Cryphonectria parasitica. The main aims of this study were to provide molecular characterization of CHV1 from Croatia and Slovenia and to reveal its genetic variability, phylogeny, and diversification of populations. Fifty-one CHV1 haplotypes were detected among 54 partially sequenced CHV1 isolates, all belonging to Italian subtype (I). Diversity was mainly generated by point mutations while evidence of recombination was not found. The level of conservation over analyzed parts of ORF-A proteins p29 and p40 varied, but functional sites were highly conserved. Phylogenetic analysis revealed close relatedness and intermixing of Croatian and Slovenian CHV1 populations. Our CHV1 isolates were also related to Swiss and Bosnian hypoviruses supporting previously suggested course of CHV1 invasion in Europe. Overall, this study indicates that phylogeny of CHV1 subtype I in Europe is complex and characterized with frequent point mutations resulting in many closely related variants of the virus. Possible association between variations within CHV1 ORF-A and growth of the hypovirulent fungal isolates is tested and presented.
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Affiliation(s)
- Ljiljana Krstin
- Department of Biology, Josip Juraj Strossmayer University of Osijek, HR-31000, Osijek, Croatia
| | - Zorana Katanić
- Department of Biology, Josip Juraj Strossmayer University of Osijek, HR-31000, Osijek, Croatia
| | - Jelena Repar
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Marin Ježić
- Department of Biology, Faculty of Science, University of Zagreb, HR-10000, Zagreb, Croatia
| | - Ana Kobaš
- Department of Biology, Josip Juraj Strossmayer University of Osijek, HR-31000, Osijek, Croatia
| | - Mirna Ćurković-Perica
- Department of Biology, Faculty of Science, University of Zagreb, HR-10000, Zagreb, Croatia.
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Aulia A, Andika IB, Kondo H, Hillman BI, Suzuki N. A symptomless hypovirus, CHV4, facilitates stable infection of the chestnut blight fungus by a coinfecting reovirus likely through suppression of antiviral RNA silencing. Virology 2019; 533:99-107. [PMID: 31146252 DOI: 10.1016/j.virol.2019.05.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 05/14/2019] [Accepted: 05/14/2019] [Indexed: 01/10/2023]
Abstract
Field-collected US strain C18 of Cryphonectria parasitica, the chestnut blight fungus, was earlier reported to be infected by a double-stranded RNA virus, mycoreovirus 2 (MyRV2). Next-generation sequencing has revealed co-infection of C18 by a positive-strand RNA virus, hypovirus 4 (CHV4). The current molecular and genetic analyses showed interesting commensal interactions between the two viruses. CHV4 facilitated the stable infection and enhanced vertical transmission of MyRV2, which was readily lost during subculturing and showed reduced vertical transmission in single infections. Deletion of a key antiviral RNA silencing gene, dcl2, in isolate C18 increased stability of MyRV2 in single infections. The ability of CHV4 to facilitate stable infection with MyRV2 appears to be associated with the inhibitory effect of CHV4 on RNA silencing via compromising the induction of transcriptional up-regulation of dcl2. These results suggest that natural infection of isolate C18 by MyRV2 in the field was facilitated by CHV4 co-infection.
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Affiliation(s)
- Annisa Aulia
- Institute of Plant Science and Resources (IPSR), Okayama University, Kurashiki, 710-0046, Japan; Graduate School of Environmental and Life Science, Okayama University, Okayama, 700-8530, Japan
| | - Ida Bagus Andika
- Institute of Plant Science and Resources (IPSR), Okayama University, Kurashiki, 710-0046, Japan
| | - Hideki Kondo
- Institute of Plant Science and Resources (IPSR), Okayama University, Kurashiki, 710-0046, Japan
| | - Bradley I Hillman
- Plant Biology and Pathology, Rutgers University, New Brunswick, NJ, 08901, USA
| | - Nobuhiro Suzuki
- Institute of Plant Science and Resources (IPSR), Okayama University, Kurashiki, 710-0046, Japan.
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Wang S, Yang Z, Zhang T, Li N, Cao Q, Li G, Yuan Y, Liu D. Molecular Characterization of a Chrysovirus Isolated From the Citrus Pathogen Penicillium crustosum and Related Fungicide Resistance Analysis. Front Cell Infect Microbiol 2019; 9:156. [PMID: 31157173 PMCID: PMC6529537 DOI: 10.3389/fcimb.2019.00156] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 04/26/2019] [Indexed: 12/30/2022] Open
Abstract
Penicillium sp. are damaging to a range of foods and fruits including citrus. To date, double-stranded (ds)RNA viruses have been reported in most Penicillium species but not in citrus pathogen P. crustosum. Here we report a novel dsRNA virus, designated as Penicillium crustosum chrysovirus 1 (PcCV1) and isolated from P. crustosum strain HS-CQ15. PcCV1 genome comprises four dsRNA segments, referred to as dsRNA1, dsRNA2, dsRNA3, and dsRNA4, which are 3600, 3177, 3078, and 2808 bp in length, respectively. Sequence analysis revealed the presence of four open reading frames (ORFs) in the PcCV1 genome. ORF1 in dsRNA1 encodes a putative RNA-dependent RNA polymerase (RdRp) and ORF2 in dsRNA2 encodes a putative coat protein (CP). The two remaining ORFs, ORF3 in dsRNA3 and ORF4 in dsRNA4, encode proteins of unknown function. Phylogenetic analysis based on RdRp sequences showed that PcCV1 clusters with other members of the genus Chrysovirus, family Chrysoviridae. Transmission electron microscope (TEM) analysis revealed that the PcCV1 visions are approximately 40 nm in diameter. Regarding biological effects of PcCV1, HS-CQ15 harboring the chrysovirus exhibited no obvious difference in colony morphology under fungicide-free conditions but decreased resistance to demethylation inhibitor (DMI)-fungicide prochloraz, as compared to PcCV1-cured strain. Here we provide the first evidence of a virus present in citrus pathogenic fungus P. crustosum and the chrysovirus-induced change in fungicide-resistance of its host fungus.
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Affiliation(s)
- Shengqiang Wang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Zhu Yang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Tingfu Zhang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Na Li
- College of Life Science and Technology, Honghe University, Mengzi, China
| | - Qianwen Cao
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Guoqi Li
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Yongze Yuan
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Deli Liu
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
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Investigation of Host Range of and Host Defense against a Mitochondrially Replicating Mitovirus. J Virol 2019; 93:JVI.01503-18. [PMID: 30626664 DOI: 10.1128/jvi.01503-18] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 12/18/2018] [Indexed: 01/19/2023] Open
Abstract
Mitoviruses (genus Mitovirus, family Narnaviridae) are mitochondrially replicating viruses that have the simplest positive-sense RNA genomes of 2.2 to 4.4 kb with a single open reading frame (ORF) encoding an RNA-dependent RNA polymerase. Cryphonectria parasitica mitovirus 1 (CpMV1) from U.S. strain NB631 of the chestnut blight fungus, Cryphonectria parasitica, was the first virus identified as a mitochondrially replicating virus. Despite subsequent discovery of many other mitoviruses from diverse fungi, no great advances in understanding mitovirus biology have emerged, partly because of the lack of inoculation methods. Here we developed a protoplast fusion-based protocol for horizontal transmission of CpMV1 that entailed fusion of recipient and donor protoplasts, hyphal anastomosis, and single-conidium isolation. This method allowed expansion of the host range to many other C. parasitica strains. Species within and outside the family Cryphonectriaceae, Cryphonectria radicalis and Valsa ceratosperma, also supported the replication of CpMV1 at a level comparable to that in the natural host. No stable maintenance of CpMV1 was observed in Helminthosporium victoriae PCR-based haplotyping of virus-infected fungal strains confirmed the recipient mitochondrial genetic background. Phenotypic comparison between CpMV1-free and -infected isogenic strains revealed no overt effects of the virus. Taking advantage of the infectivity to the standard strain C. parasitica EP155, accumulation levels were compared among antiviral RNA silencing-proficient and -deficient strains in the EP155 background. Comparable accumulation levels were observed among these strains, suggesting the avoidance of antiviral RNA silencing by CpMV1, which is consistent with its mitochondrial replication. Collectively, the results of study provide a foundation to further explore the biology of mitoviruses.IMPORTANCE Capsidless mitoviruses, which are ubiquitously detected in filamentous fungi, have the simplest RNA genomes of 2.2 to 4.4 kb, encoding only RNA-dependent RNA polymerase. Despite their simple genomes, detailed biological characterization of mitoviruses has been hampered by their mitochondrial location within the cell, posing challenges to their experimental introduction and study. Here we developed a protoplast fusion-based protocol for horizontal transfer of the prototype mitovirus, Cryphonectria parasitica mitovirus 1 (CpMV1), which was isolated from strain NB631 of the chestnut blight fungus (Cryphonectria parasitica), a model filamentous fungus for studying virus-host interactions. The host range of CpMV1 has been expanded to many different strains of C. parasitica and different fungal species within and outside the Cryphonectriaceae. Comparison of CpMV1 accumulation among various RNA silencing-deficient and -competent strains showed clearly that the virus was unaffected by RNA silencing. This study provides a solid foundation for further exploration of mitovirus-host interactions.
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Niu Y, Yuan Y, Mao J, Yang Z, Cao Q, Zhang T, Wang S, Liu D. Characterization of two novel mycoviruses from Penicillium digitatum and the related fungicide resistance analysis. Sci Rep 2018; 8:5513. [PMID: 29615698 PMCID: PMC5882929 DOI: 10.1038/s41598-018-23807-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 01/03/2018] [Indexed: 01/09/2023] Open
Abstract
Pathogenic fungi including Penicillium digitatum and Penicillium italicum are the main destructive pathogens in the citrus industry, causing great losses during postharvest process. To our knowledge, only one mycovirus from P. digitatum has been reported, and the prevalence of such mycoviruses against citrus postharvest pathogenic fungi and their genotyping were still under investigation. In the present study, we showed that 39 of 152 Penicillium isolates from main citrus-growing areas in China were infected with various mycoviruses belonging to polymycoviruses, Narna-like viruses, and families Totiviridae, Partitivirdae and Chrysoviridae. The next generation sequencing (NGS) towards virus genome library and the following molecular analysis revealed two novel mycoviruses Penicillium digitatum polymycovirus 1 (PdPmV1) and Penicillium digitatum Narna-like virus 1 (PdNLV1), coexisting in P. digitatum strain HS-RH2. The fungicide-resistant P. digitatum strains HS-F6 and HS-E9 coinfected by PdPmV1 and PdNLV1 exhibited obvious reduction in triazole drug prochloraz resistance by mycelial growth analysis on both PDA plates and citrus fruit epidermis with given prochloraz concentration. This report at the first time characterized two novel mycoviruses from P. digitatum and revealed the mycovirus-induced reduction of fungicide resistance.
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Affiliation(s)
- Yuhui Niu
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, 430079, P. R. China
| | - Yongze Yuan
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, 430079, P. R. China
| | - Jiali Mao
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, 430079, P. R. China
| | - Zhu Yang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, 430079, P. R. China
| | - Qianwen Cao
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, 430079, P. R. China
| | - Tingfu Zhang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, 430079, P. R. China
| | - Shengqiang Wang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, 430079, P. R. China
| | - Deli Liu
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, 430079, P. R. China.
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Abstract
In contrast to well-established internal ribosomal entry site (IRES)-mediated translational initiation in animals and plants, no IRESs were established in fungal viral or cellular RNAs. To identify IRES elements in mycoviruses, we developed a luciferase-based dual-reporter detection system in Cryphonectria parasitica, a model filamentous fungus for virus-host interactions. A bicistronic construct entails a codon-optimized Renilla and firefly luciferase (ORluc and OFluc, respectively) gene, between which potential IRES sequences can be inserted. In this system, ORluc serves as an internal control, while OFluc represents IRES activity. Virus sequences in the 5′ untranslated regions (UTRs) of the genomes of diverse positive-sense single-stranded RNA and double-stranded RNA (dsRNA) viruses were analyzed. The results show relatively high IRES activities for Cryphonectria hypovirus 1 (CHV1) and CHV2 and faint but measurable activity for CHV3. The weak IRES signal of CHV3 may be explained by its monocistronic nature, differing from the bicistronic nature of CHV1 and CHV2. This would allow these three hypoviruses to have similar rates of translation of replication-associated protein per viral mRNA molecule. The importance of 24 5′-proximal codons of CHV1 as well as the 5′ UTR for IRES function was confirmed. Furthermore, victoriviruses and chrysoviruses tested IRES positive, whereas mycoreoviruses, partitiviruses, and quadriviruses showed similar Fluc activities as the negative controls. Overall, this study represents the first development of an IRES identification system in filamentous fungi based on the codon-optimized dual-luciferase assay and provides evidence for IRESs in filamentous fungi. Cap-independent, internal ribosomal entry site (IRES)-mediated translational initiation is often used by virus mRNAs and infrequently by cellular mRNAs in animals and plants. However, no IRESs have been established in fungal virus RNAs or cellular RNAs in filamentous fungi. Here, we report the development of a dual-luciferase assay system and measurement of the IRES activities of fungal RNA viruses in a model filamentous fungal host, Cryphonectria parasitica. Viruses identified as IRES positive include hypoviruses (positive-sense RNA viruses, members of the expanded Picornavirus supergroup), totiviruses (nonsegmented dsRNA viruses), and chrysoviruses (tetrasegmented dsRNA viruses). No IRES activities were observed in the 5′ untranslated regions of mycoreoviruses (11-segmented dsRNA viruses), quadriviruses (tetrasegmented dsRNA viruses), or partitiviruses (bisegmented dsRNA viruses). This study provides the first evidence for IRES activities in diverse RNA viruses in filamentous fungi and is a first step toward identifying trans-acting host factors and cis-regulatory viral RNA elements.
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Rigling D, Prospero S. Cryphonectria parasitica, the causal agent of chestnut blight: invasion history, population biology and disease control. MOLECULAR PLANT PATHOLOGY 2018; 19:7-20. [PMID: 28142223 PMCID: PMC6638123 DOI: 10.1111/mpp.12542] [Citation(s) in RCA: 189] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 12/19/2016] [Accepted: 01/26/2017] [Indexed: 05/25/2023]
Abstract
Chestnut blight, caused by Cryphonectria parasitica, is a devastating disease infecting American and European chestnut trees. The pathogen is native to East Asia and was spread to other continents via infected chestnut plants. This review summarizes the current state of research on this pathogen with a special emphasis on its interaction with a hyperparasitic mycovirus that acts as a biological control agent of chestnut blight. TAXONOMY Cryphonectria parasitica (Murr.) Barr. is a Sordariomycete (ascomycete) fungus in the family Cryphonectriaceae (Order Diaporthales). Closely related species that can also be found on chestnut include Cryphonectria radicalis, Cryphonectria naterciae and Cryphonectria japonica. HOST RANGE Major hosts are species in the genus Castanea (Family Fagaceae), particularly the American chestnut (C. dentata), the European chestnut (C. sativa), the Chinese chestnut (C. mollissima) and the Japanese chestnut (C. crenata). Minor incidental hosts include oaks (Quercus spp.), maples (Acer spp.), European hornbeam (Carpinus betulus) and American chinkapin (Castanea pumila). DISEASE SYMPTOMS Cryphonectria parasitica causes perennial necrotic lesions (so-called cankers) on the bark of stems and branches of susceptible host trees, eventually leading to wilting of the plant part distal to the infection. Chestnut blight cankers are characterized by the presence of mycelial fans and fruiting bodies of the pathogen. Below the canker the tree may react by producing epicormic shoots. Non-lethal, superficial or callusing cankers on susceptible host trees are usually associated with mycovirus-induced hypovirulence. DISEASE CONTROL After the introduction of C. parasitica into a new area, eradication efforts by cutting and burning the infected plants/trees have mostly failed. In Europe, the mycovirus Cryphonectria hypovirus 1 (CHV-1) acts as a successful biological control agent of chestnut blight by causing so-called hypovirulence. CHV-1 infects C. parasitica and reduces its parasitic growth and sporulation capacity. Individual cankers can be therapeutically treated with hypovirus-infected C. parasitica strains. The hypovirus may subsequently spread to untreated cankers and become established in the C. parasitica population. Hypovirulence is present in many chestnut-growing regions of Europe, either resulting naturally or after biological control treatments. In North America, disease management of chestnut blight is mainly focused on breeding with the goal to backcross the Chinese chestnut's blight resistance into the American chestnut genome.
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Affiliation(s)
- Daniel Rigling
- Swiss Federal Institute for ForestSnow and Landscape Research (WSL)Birmensdorf8903Switzerland
| | - Simone Prospero
- Swiss Federal Institute for ForestSnow and Landscape Research (WSL)Birmensdorf8903Switzerland
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A neo-virus lifestyle exhibited by a (+)ssRNA virus hosted in an unrelated dsRNA virus: Taxonomic and evolutionary considerations. Virus Res 2018; 244:75-83. [DOI: 10.1016/j.virusres.2017.11.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 11/04/2017] [Accepted: 11/05/2017] [Indexed: 12/21/2022]
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Du Y, Lin Y, Zhou X, Wang K, Fang S, Deng Q. Full-length sequence and genome analysis of CHV1-CN280, a North China isolate of cryphonectria hypovirus 1. Arch Virol 2017; 162:1811-1818. [PMID: 28247097 DOI: 10.1007/s00705-017-3296-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 02/13/2017] [Indexed: 11/29/2022]
Abstract
CHV1-CN280 is a North China isolate of cryphonectria hypovirus 1 (CHV1), which has high horizontal transmission ability. The complete genomic sequence of CHV1-CN280 was determined and analyzed. Compared with other reported CHV1s, the genome of CHV1-CN280 shows some significantly different characteristics. The junction of the two open reading frames (ORFs) of CHV1-CN280 is AUGUAUAA, while in other reported CHV1s, it is UAAUG. The genomic sequence of CHV1-CN280 shows a high level of similarity to other reported CHV1s in the 3' portion, but in some sections of the 5' portion (the region around the start codon of ORFA, the region around the predicted cleavage site of p29 and p40, and the 5'-portion of p48 coding region), the nucleotide sequence identity is lower than 50%. The p29 of CHV1-CN280 shares only about 60% identity with other sequenced CHV1 isolates at the amino acid level. Full-length genomic recombination analysis suggests that several recombination events have occurred in the ORFB coding region between CHV1-CN280 and two subtype I CHV1 isolates (CHV1-Euro7 or CHV1-EP721). RT-PCR primers were designed according to the genomic sequence of CHV1-CN280 to study the genetic diversity of CHV1 in East Asia. Phylogenetic analysis showed that the East Asian CHV1s were quite different from the five assigned subtypes in Europe, and seven new CHV1 subtypes were identified in this study.
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Affiliation(s)
- Yanan Du
- Hubei Collaborative Innovation Center for Grain Industry, Engineering Research Center of Ecology and Agricultural Use of Wetland, College of Agriculture, Yangtze University, Ministry of Education, Jingzhou, 434025, Hubei, China
| | - Yuan Lin
- Hubei Collaborative Innovation Center for Grain Industry, Engineering Research Center of Ecology and Agricultural Use of Wetland, College of Agriculture, Yangtze University, Ministry of Education, Jingzhou, 434025, Hubei, China
| | - Xuan Zhou
- Hubei Collaborative Innovation Center for Grain Industry, Engineering Research Center of Ecology and Agricultural Use of Wetland, College of Agriculture, Yangtze University, Ministry of Education, Jingzhou, 434025, Hubei, China
| | - Kerong Wang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China
| | - Shouguo Fang
- Hubei Collaborative Innovation Center for Grain Industry, Engineering Research Center of Ecology and Agricultural Use of Wetland, College of Agriculture, Yangtze University, Ministry of Education, Jingzhou, 434025, Hubei, China
| | - Qingchao Deng
- Hubei Collaborative Innovation Center for Grain Industry, Engineering Research Center of Ecology and Agricultural Use of Wetland, College of Agriculture, Yangtze University, Ministry of Education, Jingzhou, 434025, Hubei, China.
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Eusebio-Cope A, Sun L, Tanaka T, Chiba S, Kasahara S, Suzuki N. The chestnut blight fungus for studies on virus/host and virus/virus interactions: From a natural to a model host. Virology 2015; 477:164-175. [DOI: 10.1016/j.virol.2014.09.024] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2014] [Revised: 09/15/2014] [Accepted: 09/26/2014] [Indexed: 01/03/2023]
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Xie J, Jiang D. New insights into mycoviruses and exploration for the biological control of crop fungal diseases. ANNUAL REVIEW OF PHYTOPATHOLOGY 2014; 52:45-68. [PMID: 25001452 DOI: 10.1146/annurev-phyto-102313-050222] [Citation(s) in RCA: 288] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Mycoviruses are viruses that infect fungi. A growing number of novel mycoviruses have expanded our knowledge of virology, particularly in taxonomy, ecology, and evolution. Recent progress in the study of mycoviruses has comprehensively improved our understanding of the properties of mycoviruses and has strengthened our confidence to explore hypovirulence-associated mycoviruses that control crop diseases. In this review, the advantages of using hypovirulence-associated mycoviruses to control crop diseases are discussed, and, as an example, the potential for Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1 (SsHADV-1) to control the stem rot of rapeseed (Brassica napus) is also introduced. Fungal vegetative incompatibility is likely to be the key factor that limits the wide utilization of mycoviruses to control crop diseases; however, there are suggested strategies for resolving this problem.
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Affiliation(s)
- Jiatao Xie
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, Hubei Province, China;
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A novel victorivirus from a phytopathogenic fungus, Rosellinia necatrix, is infectious as particles and targeted by RNA silencing. J Virol 2013; 87:6727-38. [PMID: 23552428 DOI: 10.1128/jvi.00557-13] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
A novel victorivirus, termed Rosellinia necatrix victorivirus 1 (RnVV1), was isolated from a plant pathogenic ascomycete, white root rot fungus Rosellinia necatrix, coinfected with a partitivirus. The virus was molecularly and biologically characterized using the natural and experimental hosts (chestnut blight fungus, Cryphonectria parasitica). RnVV1 was shown to have typical molecular victorivirus attributes, including a monopartite double-stranded RNA genome with two open reading frames (ORFs) encoding capsid protein (CP) and RNA-dependent RNA polymerase (RdRp), a UAAUG pentamer presumed to facilitate the coupled termination/reinitiation for translation of the two ORFs, a spherical particle structure ~40 nm in diameter, and moderate levels of CP and RdRp sequence identity (34 to 58%) to those of members of the genus Victorivirus within the family Totiviridae. A reproducible transfection system with purified RnVV1 virions was developed for the two distinct fungal hosts. Transfection assay with purified RnVV1 virions combined with virus elimination by hyphal tipping showed that the effects of RnVV1 on the phenotype of the natural host were negligible. Interestingly, comparison of the RNA silencing-competent (standard strain EP155) and -defective (Δdcl-2) strains of C. parasitica infected with RnVV1 showed that RNA silencing acted against the virus to repress its replication, which was restored by coinfection with hypovirus or transgenic expression of an RNA silencing suppressor, hypovirus p29. Phenotypic changes were observed in the Δdcl-2 strain but not in EP155. This is the first reported study on the host range expansion of a Totiviridae member that is targeted by RNA silencing.
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Brusini J, Robin C, Franc A. Parasitism and maintenance of diversity in a fungal vegetative incompatibility system: the role of selection by deleterious cytoplasmic elements. Ecol Lett 2011; 14:444-52. [PMID: 21382145 DOI: 10.1111/j.1461-0248.2011.01602.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In fungi, horizontal transmission of deleterious cytoplasmic elements is reduced by the vegetative incompatibility system. This self/non-self recognition system may select for greater diversity of fungal incompatibility phenotypes in a frequency-dependent manner but the link between the diversity of fungal phenotypes and the virulence of cytoplasmic parasites has been poorly studied. We used an epidemiological model to show that even when transmission between incompatibility types is permitted, parasite pressure can lead to high levels of polymorphism for vegetative incompatibility systems. Moreover, high levels of polymorphism in host populations can select for less virulent cytoplasmic parasites. This feedback mechanism between parasite virulence and vegetative incompatibility system polymorphism of host populations may account for the general avirulence of most known mycoviruses. Furthermore, this mechanism provides a new perspective on the particular ecology and evolution of the host/parasite interactions acting between fungi and their cytoplasmic parasites.
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Affiliation(s)
- Jérémie Brusini
- INRA, UMR 1202 Biodiversity, Genes & Communities, 69 Route d'Arcachon, F-33610 Cestas, France.
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Jamal A, Bignell EM, Coutts RHA. Complete nucleotide sequences of four dsRNAs associated with a new chrysovirus infecting Aspergillus fumigatus. Virus Res 2010; 153:64-70. [PMID: 20621139 DOI: 10.1016/j.virusres.2010.07.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 07/01/2010] [Accepted: 07/05/2010] [Indexed: 12/26/2022]
Abstract
A new double-stranded RNA (dsRNA) virus designated A. fumigatus chrysovirus (AfuCV), belonging to the family Chrysoviridae, has been identified in the filamentous fungus Aspergillus fumigatus. The virus was detected in five of 390 A. fumigatus isolates screened. Analysis of purified dsRNA revealed four distinct species 3560, 3159, 3006 and 2863 base pairs in length (dsRNAs 1-4) which were cloned and sequenced. Each dsRNA contains a single open reading frame (ORF) with short 5' and 3' untranslated regions containing strictly conserved termini. The deduced 1114 amino acid (aa) protein (molecular mass=128 kDa) encoded by the dsRNA1 ORF showed homology to the RNA-dependent RNA polymerase (RdRP) of viruses belonging to the Chrysoviridae. Eight motifs characteristic of RdRPs were identified. The dsRNA2 ORF encodes the putative coat protein subunit (953aa; molecular mass=107 kDa). The dsRNA3 and dsRNA4 ORFs respectively encode putative proteins (891aa, molecular mass=99 kDa) and (847aa, molecular mass=95 kDa), both of which have significant similarity to proteins encoded by comparable chrysovirus dsRNAs. The dsRNA profile, amino acid sequence alignments, and phylogenetic analyses all indicate that AfuCV is a new species within the family Chrysoviridae.
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Affiliation(s)
- Atif Jamal
- Division of Biology, Faculty of Natural Sciences Imperial College London, Sir Alexander Fleming Building, Imperial College Road, London SW7 2AZ, United Kingdom
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Kim JM, Park JA, Park SM, Cha BJ, Yang MS, Kim DH. Nucleotide sequences of four segments of chrysovirus in Korean Cryphonectria nitschkei BS122 strain. Virus Genes 2010; 41:292-4. [PMID: 20549324 DOI: 10.1007/s11262-010-0495-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Accepted: 05/22/2010] [Indexed: 10/19/2022]
Abstract
The near full-length genome consisting of four segments of dsRNA from a chrysovirus infecting Korean Cryphonectria nitschkei BS122 strain (CnV1-BS122) was sequenced. The open reading frames of segments 1, 2, 3, and 4 were 2,889, 2,721, 2,475, and 2,232 nucleotides (nt) in length, respectively. Sequence analysis and homology searches of the amino acid sequences deduced from the ORFs of each segment revealed that segments 1, 2, 3, and 4 encoded RNA-dependent RNA polymerase, capsid protein, a putative cysteine protease, and replication-associated protein, respectively. The entire 5' ends of segments 1, 2, and 4 were 82, 242, and 698 nt in length, respectively; the sequence of the 5' end of segment 3 was not determined because of difficulty in amplification. The entire 3' end of segment 3 was 77 nt in length. Partial amplification of the 3' ends of segments 1, 2, and 4 yielded amplimers of 7, 17, and 30 nt, respectively.
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Affiliation(s)
- Jung-Mi Kim
- Division of Biological Sciences, Institute of Molecular Biology and Genetics, Center for Fungal Pathogenesis, Chonbuk National University, Chonbuk, Korea
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Molecular diversity of chrysoviruses in Korean isolates of a new fungal species, Cryphonectria nitschkei. J Microbiol 2009; 47:441-7. [PMID: 19763418 DOI: 10.1007/s12275-009-0206-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Accepted: 07/24/2009] [Indexed: 10/20/2022]
Abstract
Genetic diversity of the chrysovirus within the four fungal strains was analyzed by comparing the full-length sequences of cloned chrysoviral genes encoding the RNA-dependent RNA polymerase (RdRp) and capsid protein (CP). Because the morphological characteristics of four chrysovirus-infected Cryphonectria spp. strains were different, strain identification was conducted via sequence comparison of the internal transcribed spacers (ITSs) of the fungal rRNA gene. Phylogenic analysis of the ITS regions revealed that the four strains were closely clustered with the reference strain of Cryphonectria nitschkei, while they were more distantly related to other common Cryphonectria species, indicating that they were likely C. nitschkei. Sequence comparison among chrysoviruses from Korean C. nitschkei strains revealed that similarities of the RdRp and CP genes ranged from 98% to 100% and from 95% to 100%, respectively, at the protein level. Their corresponding nucleotide sequences showed 97% to 100% and 84% to 100% identities, respectively. Compared to RdRp, the CP gene had more divergence, suggesting the presence of genes possessing different evolutionary rates within the chrysovirus genome. Sequence comparisons with other known chrysoviruses showed that the four Korean chrysoviruses were clustered together at the next lineage level. Discovering why two strains (bsl31 and bsl32) containing identical ITS sequences and chrysoviruses display different phenotypes should prove interesting.
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Abstract
Mycoviruses are widespread in all major groups of plant pathogenic fungi. They are transmitted intracellularly during cell division, sporogenesis, and cell fusion, but apparently lack an extracellular route for infection. Their natural host ranges are limited to individuals within the same or closely related vegetative compatibility groups. Recent advances, however, allowed the establishment of experimental host ranges for a few mycoviruses. Although the majority of known mycoviruses have dsRNA genomes that are packaged in isometric particles, an increasing number of usually unencapsidated mycoviruses with positive-strand RNA genomes have been reported. We discuss selected mycoviruses that cause debilitating diseases and/or reduce the virulence of their phytopathogenic fungal hosts. Such fungal-virus systems are valuable for the development of novel biocontol strategies and for gaining an insight into the molecular basis of fungal virulence. The availability of viral and host genome sequences and of transformation and transfection protocols for some plant pathogenic fungi will contribute to progress in fungal virology.
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Affiliation(s)
- Said A Ghabrial
- Plant Pathology Department, University of Kentucky, Lexington, Kentucky 40546, USA.
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Pearson MN, Beever RE, Boine B, Arthur K. Mycoviruses of filamentous fungi and their relevance to plant pathology. MOLECULAR PLANT PATHOLOGY 2009; 10:115-28. [PMID: 19161358 PMCID: PMC6640375 DOI: 10.1111/j.1364-3703.2008.00503.x] [Citation(s) in RCA: 326] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Mycoviruses (fungal viruses) are reviewed with emphasis on plant pathogenic fungi. Based on the presence of virus-like particles and unencapsidated dsRNAs, mycoviruses are common in all major fungal groups. Over 80 mycovirus species have been officially recognized from ten virus families, but a paucity of nucleic acid sequence data makes assignment of many reported mycoviruses difficult. Although most of the particle types recognized to date are isometric, a variety of morphologies have been found and, additionally, many apparently unencapsidated dsRNAs have been reported. Until recently, most characterized mycoviruses have dsRNA genomes, but ssRNA mycoviruses now constitute about one-third of the total. Two hypotheses for the origin of mycoviruses of plant pathogens are discussed: the first that they are of unknown but ancient origin and have coevolved along with their hosts, the second that they have relatively recently moved from a fungal plant host into the fungus. Although mycoviruses are typically readily transmitted through asexual spores, transmission through sexual spores varies with the host fungus. Evidence for natural horizontal transmission has been found. Typically, mycoviruses are apparently symptomless (cryptic) but beneficial effects on the host fungus have been reported. Of more practical interest to plant pathologists are those viruses that confer a hypovirulent phenotype, and the scope for using such viruses as biocontrol agents is reviewed. New tools are being developed based on host genome studies that will help to address the intellectual challenge of understanding the fungal-virus interactions and the practical challenge of manipulating this relationship to develop novel biocontrol agents for important plant pathogens.
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Affiliation(s)
- Michael N Pearson
- School of Biological Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
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