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Khan HA, Baig DI, Bhatti MF. An Overview of Mycoviral Curing Strategies Used in Evaluating Fungal Host Fitness. Mol Biotechnol 2023; 65:1547-1564. [PMID: 36841858 PMCID: PMC9963364 DOI: 10.1007/s12033-023-00695-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 02/11/2023] [Indexed: 02/27/2023]
Abstract
The number of novel mycoviruses is increasing at a high pace due to advancements in sequencing technologies. As a result, an uncountable number of mycoviral sequences are available in public sequence repositories. However, only genomic information is not sufficient to understand the impact of mycoviruses on their host biology. Biological characterization is required to determine the nature of mycoviruses (cryptic, hypervirulent, or hypovirulent) and to search for mycoviruses with biocontrol and therapeutic potential. Currently, no particular selective method is used as the gold standard against these mycoviral infections. Given the importance of curing, we present an overview of procedures used in preparation of isogenic lines, along with their benefits and drawbacks. We concluded that a combination of single-spore isolation and hyphal tipping is the best fit for preparation of isogenic lines. Furthermore, recent bioinformatic approaches should be introduced in the field of mycovirology to predict virus-specific antivirals to get robust results.
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Affiliation(s)
- Haris Ahmed Khan
- Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST), H-12, Islamabad, 44000 Pakistan
- Department of Biotechnology, University of Mianwali, Punjab, 42200 Pakistan
| | - Danish Ilyas Baig
- Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST), H-12, Islamabad, 44000 Pakistan
| | - Muhammad Faraz Bhatti
- Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST), H-12, Islamabad, 44000 Pakistan
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2
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Khan HA, Nerva L, Bhatti MF. The good, the bad and the cryptic: The multifaceted roles of mycoviruses and their potential applications for a sustainable agriculture. Virology 2023; 585:259-269. [PMID: 37453341 DOI: 10.1016/j.virol.2023.07.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 07/05/2023] [Accepted: 07/07/2023] [Indexed: 07/18/2023]
Abstract
Mycoviruses are natural inhabitants of fungi and have been identified in almost all fungal taxonomic groups. Mycoviruses that infect phytopathogenic fungi are now becoming a hot research area due to their potential for the biocontrol of important plant pathogens. But, before considering a mycovirus for biocontrol, we should be fully aware of the effects it induces in a fungal host and its interactions with other viruses, fungal strains and even the host plants. Mycoviral infections are generally associated with different effects, ranging from hypovirulence to hypervirulence, but they can often be cryptic (latent infections). The cryptic lifestyle has been associated to many mycoviruses, but thanks to growing knowledge we are now aware that it is often associated to axenic conditions while the real effects can be observed only in nature. Other mycoviruses either promote (hypervirulence) or (hypovirulence) fungal pathogenicity by a strong impact on the fungal physiology or by blocking the production of toxins or effectors. Finally, indirect effects of mycoviral infections can also be provided to the plant that hosts the fungal isolate, highlighting not only their potential as direct biocontrol agents but also as priming agents for plant resilience to biotic and abiotic stresses. This review provides a broad overview of mycoviral interactions both with their hosts and with other mycoviruses, highlighting the most interesting examples. In contrast to what has been observed to date, we believe that the collective availability of these data will not only improve our understanding of mycoviruses, but also increase our confidence in considering them as alternative measures against fungal diseases to improve the sustainable production of food and feed commodities.
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Affiliation(s)
- Haris Ahmed Khan
- Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST), H-12, 44000, Islamabad, Pakistan; Department of Biotechnology, University of Mianwali, Punjab, 42200, Pakistan
| | - Luca Nerva
- Research Centre for Viticulture and Enology, Council for Agricultural Research and Economics (CREA-VE), Via XXVIII Aprile, 31015, Conegliano, (TV), Italy.
| | - Muhammad Faraz Bhatti
- Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST), H-12, 44000, Islamabad, Pakistan
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Wang P, Yang G, Shi N, Zhao C, Hu F, Coutts RHA, Kotta-Loizou I, Huang B. A novel partitivirus orchestrates conidiation, stress response, pathogenicity, and secondary metabolism of the entomopathogenic fungus Metarhizium majus. PLoS Pathog 2023; 19:e1011397. [PMID: 37216409 DOI: 10.1371/journal.ppat.1011397] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 05/01/2023] [Indexed: 05/24/2023] Open
Abstract
Mycoviruses are widely present in all major groups of fungi but those in entomopathogenic Metarhizium spp. remain understudied. In this investigation, a novel double-stranded (ds) RNA virus is isolated from Metarhizium majus and named Metarhizium majus partitivirus 1 (MmPV1). The complete genome sequence of MmPV1 comprises two monocistronic dsRNA segments (dsRNA 1 and dsRNA 2), which encode an RNA-dependent RNA polymerase (RdRp) and a capsid protein (CP), respectively. MmPV1 is classified as a new member of the genus Gammapartitivirus in the family Partitiviridae based on phylogenetic analysis. As compared to an MmPV1-free strain, two isogenic MmPV1-infected single-spore isolates were compromised in terms of conidiation, and tolerance to heat shock and UV-B irradiation, while these phenotypes were accompanied by transcriptional suppression of multiple genes involved in conidiation, heat shock response and DNA damage repair. MmPV1 attenuated fungal virulence since infection resulted in reduced conidiation, hydrophobicity, adhesion, and cuticular penetration. Additionally, secondary metabolites were significantly altered by MmPV1 infection, including reduced production of triterpenoids, and metarhizins A and B, and increased production of nitrogen and phosphorus compounds. However, expression of individual MmPV1 proteins in M. majus had no impact on the host phenotype, suggesting insubstantive links between defective phenotypes and a single viral protein. These findings indicate that MmPV1 infection decreases M. majus fitness to its environment and its insect-pathogenic lifestyle and environment through the orchestration of the host conidiation, stress tolerance, pathogenicity, and secondary metabolism.
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Affiliation(s)
- Ping Wang
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
| | - Guogen Yang
- Anhui Province Key Laboratory of Integrated Pest Management on Crops, School of Plant Protection, Anhui Agricultural University, Hefei, China
| | - Najie Shi
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
| | - Cheng Zhao
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
| | - Fenglin Hu
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
| | - Robert H A Coutts
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, South Kensington Campus, London, United Kingdom
| | - Ioly Kotta-Loizou
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, South Kensington Campus, London, United Kingdom
| | - Bo Huang
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
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Wang H, Salaipeth L, Miyazaki N, Suzuki N, Okamoto K. Capsid structure of a fungal dsRNA megabirnavirus reveals its previously unidentified surface architecture. PLoS Pathog 2023; 19:e1011162. [PMID: 36848381 PMCID: PMC9997902 DOI: 10.1371/journal.ppat.1011162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 03/09/2023] [Accepted: 01/25/2023] [Indexed: 03/01/2023] Open
Abstract
Rosellinia necatrix megabirnavirus 1-W779 (RnMBV1) is a non-enveloped icosahedral double-stranded (ds)RNA virus that infects the ascomycete fungus Rosellinia necatrix, a causative agent that induces a lethal plant disease white root rot. Herein, we have first resolved the atomic structure of the RnMBV1 capsid at 3.2 Å resolution using cryo-electron microscopy (cryo-EM) single-particle analysis. Compared with other non-enveloped icosahedral dsRNA viruses, the RnMBV1 capsid protein structure exhibits an extra-long C-terminal arm and a surface protrusion domain. In addition, the previously unrecognized crown proteins are identified in a symmetry-expanded cryo-EM model and are present over the 3-fold axes. These exclusive structural features of the RnMBV1 capsid could have been acquired for playing essential roles in transmission and/or particle assembly of the megabirnaviruses. Our findings, therefore, will reinforce the understanding of how the structural and molecular machineries of the megabirnaviruses influence the virulence of the disease-related ascomycete fungus.
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Affiliation(s)
- Han Wang
- The Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Lakha Salaipeth
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, Japan
| | - Naoyuki Miyazaki
- Life Science Center of Survival Dynamics, Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Ibaraki, Japan
- * E-mail: (NM); (NS); (KO)
| | - Nobuhiro Suzuki
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, Japan
- * E-mail: (NM); (NS); (KO)
| | - Kenta Okamoto
- The Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
- * E-mail: (NM); (NS); (KO)
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Ayllón MA, Vainio EJ. Mycoviruses as a part of the global virome: Diversity, evolutionary links and lifestyle. Adv Virus Res 2023; 115:1-86. [PMID: 37173063 DOI: 10.1016/bs.aivir.2023.02.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Knowledge of mycovirus diversity, evolution, horizontal gene transfer and shared ancestry with viruses infecting distantly related hosts, such as plants and arthropods, has increased vastly during the last few years due to advances in the high throughput sequencing methodologies. This also has enabled the discovery of novel mycoviruses with previously unknown genome types, mainly new positive and negative single-stranded RNA mycoviruses ((+) ssRNA and (-) ssRNA) and single-stranded DNA mycoviruses (ssDNA), and has increased our knowledge of double-stranded RNA mycoviruses (dsRNA), which in the past were thought to be the most common viruses infecting fungi. Fungi and oomycetes (Stramenopila) share similar lifestyles and also have similar viromes. Hypothesis about the origin and cross-kingdom transmission events of viruses have been raised and are supported by phylogenetic analysis and by the discovery of natural exchange of viruses between different hosts during virus-fungus coinfection in planta. In this review we make a compilation of the current information on the genome organization, diversity and taxonomy of mycoviruses, discussing their possible origins. Our focus is in recent findings suggesting the expansion of the host range of many viral taxa previously considered to be exclusively fungal, but we also address factors affecting virus transmissibility and coexistence in single fungal or oomycete isolates, as well as the development of synthetic mycoviruses and their use in investigating mycovirus replication cycles and pathogenicity.
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Affiliation(s)
- María A Ayllón
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación Agraria y Alimentaria (INIA/CSIC), Campus de Montegancedo, Pozuelo de Alarcón, Madrid, Spain; Departamento Biotecnología-Biología Vegetal, E.T.S.I. Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid (UPM), Madrid, Spain.
| | - Eeva J Vainio
- Forest Health and Biodiversity, Natural Resources Institute Finland (Luke), Helsinki, Finland
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Bocos-Asenjo IT, Niño-Sánchez J, Ginésy M, Diez JJ. New Insights on the Integrated Management of Plant Diseases by RNA Strategies: Mycoviruses and RNA Interference. Int J Mol Sci 2022; 23:9236. [PMID: 36012499 PMCID: PMC9409477 DOI: 10.3390/ijms23169236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Revised: 08/09/2022] [Accepted: 08/15/2022] [Indexed: 11/25/2022] Open
Abstract
RNA-based strategies for plant disease management offer an attractive alternative to agrochemicals that negatively impact human and ecosystem health and lead to pathogen resistance. There has been recent interest in using mycoviruses for fungal disease control after it was discovered that some cause hypovirulence in fungal pathogens, which refers to a decline in the ability of a pathogen to cause disease. Cryphonectria parasitica, the causal agent of chestnut blight, has set an ideal model of management through the release of hypovirulent strains. However, mycovirus-based management of plant diseases is still restricted by limited approaches to search for viruses causing hypovirulence and the lack of protocols allowing effective and systemic virus infection in pathogens. RNA interference (RNAi), the eukaryotic cell system that recognizes RNA sequences and specifically degrades them, represents a promising. RNA-based disease management method. The natural occurrence of cross-kingdom RNAi provides a basis for host-induced gene silencing, while the ability of most pathogens to uptake exogenous small RNAs enables the use of spray-induced gene silencing techniques. This review describes the mechanisms behind and the potential of two RNA-based strategies, mycoviruses and RNAi, for plant disease management. Successful applications are discussed, as well as the research gaps and limitations that remain to be addressed.
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Affiliation(s)
- Irene Teresa Bocos-Asenjo
- Department of Plant Production and Forest Resources, University of Valladolid, 34004 Palencia, Spain
- iuFOR-Sustainable Forest Management Research Institute, University of Valladolid-INIA, 34004 Palencia, Spain
| | - Jonatan Niño-Sánchez
- Department of Plant Production and Forest Resources, University of Valladolid, 34004 Palencia, Spain
- iuFOR-Sustainable Forest Management Research Institute, University of Valladolid-INIA, 34004 Palencia, Spain
| | - Mireille Ginésy
- Department of Plant Production and Forest Resources, University of Valladolid, 34004 Palencia, Spain
- iuFOR-Sustainable Forest Management Research Institute, University of Valladolid-INIA, 34004 Palencia, Spain
| | - Julio Javier Diez
- Department of Plant Production and Forest Resources, University of Valladolid, 34004 Palencia, Spain
- iuFOR-Sustainable Forest Management Research Institute, University of Valladolid-INIA, 34004 Palencia, Spain
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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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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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