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Mahillon M, Brodard J, Schoen R, Botermans M, Dubuis N, Groux R, Pannell JR, Blouin AG, Schumpp O. Revisiting a pollen-transmitted ilarvirus previously associated with angular mosaic of grapevine. Virus Res 2024; 344:199362. [PMID: 38508402 PMCID: PMC10979282 DOI: 10.1016/j.virusres.2024.199362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 03/17/2024] [Accepted: 03/18/2024] [Indexed: 03/22/2024]
Abstract
We report the characterization of a novel tri-segmented RNA virus infecting Mercurialis annua, a common crop weed and model species in plant science. The virus, named "Mercurialis latent virus" (MeLaV) was first identified in a mixed infection with the recently described Mercurialis orthotospovirus 1 (MerV1) on symptomatic plants grown in glasshouses in Lausanne (Switzerland). Both viruses were found to be transmitted by Thrips tabaci, which presumably help the inoculation of infected pollen in the case of MeLaV. Complete genome sequencing of the latter revealed a typical ilarviral architecture and close phylogenetic relationship with members of the Ilarvirus subgroup 1. Surprisingly, a short portion of MeLaV replicase was found to be identical to the partial sequence of grapevine angular mosaic virus (GAMV) reported in Greece in the early 1990s. However, we have compiled data that challenge the involvement of GAMV in angular mosaic of grapevine, and we propose alternative causal agents for this disorder. In parallel, three highly-conserved MeLaV isolates were identified in symptomatic leaf samples in The Netherlands, including a herbarium sample collected in 1991. The virus was also traced in diverse RNA sequencing datasets from 2013 to 2020, corresponding to transcriptomic analyses of M. annua and other plant species from five European countries, as well as metaviromics analyses of bees in Belgium. Additional hosts are thus expected for MeLaV, yet we argue that infected pollen grains have likely contaminated several sequencing datasets and may have caused the initial characterization of MeLaV as GAMV.
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Affiliation(s)
- Mathieu Mahillon
- Research group Virology, Bacteriology and Phytoplasmology, Department of Plant protection, Agroscope, Nyon, Switzerland
| | - Justine Brodard
- Research group Virology, Bacteriology and Phytoplasmology, Department of Plant protection, Agroscope, Nyon, Switzerland
| | - Ruben Schoen
- Netherlands Institute for Vectors, Invasive plants and Plant health (NIVIP), Netherlands Food and Consumer Product Safety Authority, Wageningen, The Netherlands
| | - Marleen Botermans
- Netherlands Institute for Vectors, Invasive plants and Plant health (NIVIP), Netherlands Food and Consumer Product Safety Authority, Wageningen, The Netherlands
| | - Nathalie Dubuis
- Research group Virology, Bacteriology and Phytoplasmology, Department of Plant protection, Agroscope, Nyon, Switzerland
| | - Raphaël Groux
- Research group Virology, Bacteriology and Phytoplasmology, Department of Plant protection, Agroscope, Nyon, Switzerland
| | - John R Pannell
- Department of Ecology and Evolution, University of Lausanne (UNIL), Switzerland
| | - Arnaud G Blouin
- Research group Virology, Bacteriology and Phytoplasmology, Department of Plant protection, Agroscope, Nyon, Switzerland
| | - Olivier Schumpp
- Research group Virology, Bacteriology and Phytoplasmology, Department of Plant protection, Agroscope, Nyon, Switzerland.
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Smadi M, Lee E, Phelan J, Wang A, Bilodeau GJ, Pernal SF, Guarna MM, Rott M, Griffiths JS. Plant virus diversity in bee and pollen samples from apple ( Malus domestica) and sweet cherry ( Prunus avium) agroecosystems. FRONTIERS IN PLANT SCIENCE 2024; 15:1335281. [PMID: 38444533 PMCID: PMC10913894 DOI: 10.3389/fpls.2024.1335281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 01/05/2024] [Indexed: 03/07/2024]
Abstract
Introduction Honey bee (Apis mellifera) pollination is widely used in tree fruit production systems to improve fruit set and yield. Many plant viruses can be associated with pollen or transmitted through pollination, and can be detected through bee pollination activities. Honey bees visit multiple plants and flowers in one foraging trip, essentially sampling small amounts of pollen from a wide area. Here we report metagenomics-based area-wide monitoring of plant viruses in cherry (Prunus avium) and apple (Malus domestica) orchards in Creston Valley, British Columbia, Canada, through bee-mediated pollen sampling. Methods Plant viruses were identified in total RNA extracted from bee and pollen samples, and compared with profiles from double stranded RNA extracted from leaf and flower tissues. CVA, PDV, PNRSV, and PVF coat protein nucleotide sequences were aligned and compared for phylogenetic analysis. Results A wide array of plant viruses were identified in both systems, with cherry virus A (CVA), prune dwarf virus (PDV), prunus necrotic ringspot virus (PNRSV), and prunus virus F (PVF) most commonly detected. Citrus concave gum associated virus and apple stem grooving virus were only identified in samples collected during apple bloom, demonstrating changing viral profiles from the same site over time. Different profiles of viruses were identified in bee and pollen samples compared to leaf and flower samples reflective of pollen transmission affinity of individual viruses. Phylogenetic and pairwise analysis of the coat protein regions of the four most commonly detected viruses showed unique patterns of nucleotide sequence diversity, which could have implications in their evolution and management approaches. Coat protein sequences of CVA and PVF were broadly diverse with multiple distinct phylogroups identified, while PNRSV and PDV were more conserved. Conclusion The pollen virome in fruit production systems is incredibly diverse, with CVA, PDV, PNRSV, and PVF widely prevalent in this region. Bee-mediated monitoring in agricultural systems is a powerful approach to study viral diversity and can be used to guide more targeted management approaches.
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Affiliation(s)
- Malek Smadi
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, Canada
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Eunseo Lee
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, Canada
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - James Phelan
- Canadian Food Inspection Agency, Centre for Plant Health, Sidney Laboratory, North Saanich, BC, Canada
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, Canada
| | | | - Stephen F. Pernal
- Beaverlodge Research Farm, Agriculture and Agri-Food Canada, Beaverlodge, AB, Canada
| | - M. Marta Guarna
- Beaverlodge Research Farm, Agriculture and Agri-Food Canada, Beaverlodge, AB, Canada
- Department of Computer Science, University of Victoria, Victoria, BC, Canada
| | - Mike Rott
- Canadian Food Inspection Agency, Centre for Plant Health, Sidney Laboratory, North Saanich, BC, Canada
| | - Jonathan S. Griffiths
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, Canada
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Mahillon M, Brodard J, Dubuis N, Gugerli P, Blouin AG, Schumpp O. Mixed infection of ITPase-encoding potyvirid and secovirid in Mercurialis perennis: evidences for a convergent euphorbia-specific viral counterstrike. Virol J 2024; 21:6. [PMID: 38178191 PMCID: PMC10768138 DOI: 10.1186/s12985-023-02257-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 12/04/2023] [Indexed: 01/06/2024] Open
Abstract
BACKGROUND In cellular organisms, inosine triphosphate pyrophosphatases (ITPases) prevent the incorporation of mutagenic deaminated purines into nucleic acids. These enzymes have also been detected in the genomes of several plant RNA viruses infecting two euphorbia species. In particular, two ipomoviruses produce replicase-associated ITPases to cope with high concentration of non-canonical nucleotides found in cassava tissues. METHOD Using high-throughput RNA sequencing on the wild euphorbia species Mercurialis perennis, two new members of the families Potyviridae and Secoviridae were identified. Both viruses encode for a putative ITPase, and were found in mixed infection with a new partitivirid. Following biological and genomic characterization of these viruses, the origin and function of the phytoviral ITPases were investigated. RESULTS While the potyvirid was shown to be pathogenic, the secovirid and partitivirid could not be transmitted. The secovirid was found belonging to a proposed new Comovirinae genus tentatively named "Mercomovirus", which also accommodates other viruses identified through transcriptome mining, and for which an asymptomatic pollen-associated lifestyle is suspected. Homology and phylogenetic analyses inferred that the ITPases encoded by the potyvirid and secovirid were likely acquired through independent horizontal gene transfer events, forming lineages distinct from the enzymes found in cassava ipomoviruses. Possible origins from cellular organisms are discussed for these proteins. In parallel, the endogenous ITPase of M. perennis was predicted to encode for a C-terminal nuclear localization signal, which appears to be conserved among the ITPases of euphorbias but absent in other plant families. This subcellular localization is in line with the idea that nucleic acids remain protected in the nucleus, while deaminated nucleotides accumulate in the cytoplasm where they act as antiviral molecules. CONCLUSION Three new RNA viruses infecting M. perennis are described, two of which encoding for ITPases. These enzymes have distinct origins, and are likely required by viruses to circumvent high level of cytoplasmic non-canonical nucleotides. This putative plant defense mechanism has emerged early in the evolution of euphorbias, and seems to specifically target certain groups of RNA viruses infecting perennial hosts.
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Affiliation(s)
- Mathieu Mahillon
- Research Group Virology, Bacteriology and Phytoplasmology, Plant Protection Department, Agroscope, Nyon, Switzerland
| | - Justine Brodard
- Research Group Virology, Bacteriology and Phytoplasmology, Plant Protection Department, Agroscope, Nyon, Switzerland
| | - Nathalie Dubuis
- Research Group Virology, Bacteriology and Phytoplasmology, Plant Protection Department, Agroscope, Nyon, Switzerland
| | - Paul Gugerli
- Research Group Virology, Bacteriology and Phytoplasmology, Plant Protection Department, Agroscope, Nyon, Switzerland
| | - Arnaud G Blouin
- Research Group Virology, Bacteriology and Phytoplasmology, Plant Protection Department, Agroscope, Nyon, Switzerland
| | - Olivier Schumpp
- Research Group Virology, Bacteriology and Phytoplasmology, Plant Protection Department, Agroscope, Nyon, Switzerland.
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