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Apalowo OA, Adediji AO, Balogun OS, Fakolujo TI, Archibong JM, Izuogu NB, Abdelgawad MA, Ghoneim MM, Mustapha S, Qashqari FSI, Batiha GE, Atiri GI. Genetic Structure of Cucumber Mosaic Virus From Natural Hosts in Nigeria Reveals High Diversity and Occurrence of Putative Novel Recombinant Strains. Front Microbiol 2022; 13:753054. [PMID: 35222322 PMCID: PMC8866732 DOI: 10.3389/fmicb.2022.753054] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 01/10/2022] [Indexed: 11/13/2022] Open
Abstract
Cucumber mosaic virus (CMV, Bromoviridae: Cucummovirus), one of the most widespread plant viruses with several hosts, causes huge losses in yield quality and quantity. The occurrence of various CMV strains and high genetic diversity within the virus complicate its management. We describe the population structure of CMV in Nigeria using partial RNA1 and RNA3 gene sequences from three natural hosts: pepper (Capsicum annuum), tomato (Solanum lycopersicum), and watermelon (Citrullus lanatus). One hundred and six leaf samples were obtained from 16 locations across Nigeria, and specific primers were used to amplify the two gene fragments using PCR. Twenty-four samples tested positive for CMV using RNA1 primers, and amplicons were sequenced from 12 isolates, revealing 82.94–99.80% nucleotide and 85.42–100% amino acid sequence similarities within the population. The partial RNA3 fragment, corresponding to the complete coat protein (CP) gene, was sequenced from seven isolates, with 95.79–97.90% and 98.62–100% nucleotide and amino acid intrapopulation similarities, respectively. The isolates belonged to subgroup IB and formed distinct phylogenetic clusters in both gene sets, indicating putative novel strains. Recombination signals, supported by phylogenetic inferences, were detected within the RNA1 dataset (P ≤ 0.05) and identified a recombinant isolate within the Nigerian sequences. No recombination was detected within the CP genes. Population genetics parameters established high diversity within the Nigerian population compared to other isolates worldwide, while selection pressure estimates revealed the existence of negative selection in both gene sets. Although CMV subgroup IB strains were postulated to originate from Asia, this study reveals their prevalence across several hosts from different locations in Nigeria. To our knowledge, this is the first comprehensive description of a recombinant CMV subgroup IB isolate from West Africa, which has implications for its robust detection and overall management.
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Affiliation(s)
- Oluropo A. Apalowo
- Department of Crop Science and Horticulture, Faculty of Agriculture, Nnamdi Azikiwe University, Awka, Nigeria
- Department of Crop Protection, Faculty of Agriculture, University of Ilorin, Ilorin, Nigeria
| | - Adedapo O. Adediji
- Department of Crop Protection and Environmental Biology, Faculty of Agriculture, University of Ibadan, Ibadan, Nigeria
- *Correspondence: Adedapo O. Adediji,
| | - Olusegun S. Balogun
- Department of Crop Protection, Faculty of Agriculture, University of Ilorin, Ilorin, Nigeria
| | - Temitope I. Fakolujo
- Department of Crop Protection and Environmental Biology, Faculty of Agriculture, University of Ibadan, Ibadan, Nigeria
| | - Joy M. Archibong
- Department of Crop Protection and Environmental Biology, Faculty of Agriculture, University of Ibadan, Ibadan, Nigeria
| | - Nkechi B. Izuogu
- Department of Crop Protection, Faculty of Agriculture, University of Ilorin, Ilorin, Nigeria
| | - Mohamed A. Abdelgawad
- Department of Pharmaceutical Chemistry, College of Pharmacy, Jouf University, Sakaka, Saudi Arabia
| | - Mohammed M. Ghoneim
- Department of Pharmacy Practice, Faculty of Pharmacy, AlMaarefa University, Ad Diriyah, Saudi Arabia
| | - Suleiman Mustapha
- Department of Crop Protection, Faculty of Agriculture, University of Ilorin, Ilorin, Nigeria
- Division of Crop Protection, ICAR-Indian Institute of Horticultural Research, Bengaluru, India
| | - Fadi S. I. Qashqari
- Department of Microbiology, College of Medicine, Umm Al-Qura University, Makkah, Saudi Arabia
| | - Gaber E. Batiha
- Department of Pharmacology and Therapeutics, Faculty of Veterinary Medicine, Damanhour University, Damanhour, Egypt
| | - Gabriel I. Atiri
- Department of Crop Protection and Environmental Biology, Faculty of Agriculture, University of Ibadan, Ibadan, Nigeria
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Muslin C, Mac Kain A, Bessaud M, Blondel B, Delpeyroux F. Recombination in Enteroviruses, a Multi-Step Modular Evolutionary Process. Viruses 2019; 11:E859. [PMID: 31540135 PMCID: PMC6784155 DOI: 10.3390/v11090859] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/05/2019] [Accepted: 09/06/2019] [Indexed: 01/15/2023] Open
Abstract
RNA recombination is a major driving force in the evolution and genetic architecture shaping of enteroviruses. In particular, intertypic recombination is implicated in the emergence of most pathogenic circulating vaccine-derived polioviruses, which have caused numerous outbreaks of paralytic poliomyelitis worldwide. Recent experimental studies that relied on recombination cellular systems mimicking natural genetic exchanges between enteroviruses provided new insights into the molecular mechanisms of enterovirus recombination and enabled to define a new model of genetic plasticity for enteroviruses. Homologous intertypic recombinant enteroviruses that were observed in nature would be the final products of a multi-step process, during which precursor nonhomologous recombinant genomes are generated through an initial inter-genomic RNA recombination event and can then evolve into a diversity of fitter homologous recombinant genomes over subsequent intra-genomic rearrangements. Moreover, these experimental studies demonstrated that the enterovirus genome could be defined as a combination of genomic modules that can be preferentially exchanged through recombination, and enabled defining the boundaries of these recombination modules. These results provided the first experimental evidence supporting the theoretical model of enterovirus modular evolution previously elaborated from phylogenetic studies of circulating enterovirus strains. This review summarizes our current knowledge regarding the mechanisms of recombination in enteroviruses and presents a new evolutionary process that may apply to other RNA viruses.
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Affiliation(s)
- Claire Muslin
- One Health Research Group, Faculty of Health Sciences, Universidad de las Américas, Quito EC170125, Pichincha, Ecuador.
| | - Alice Mac Kain
- Institut Pasteur, Viral Populations and Pathogenesis Unit, CNRS UMR 3569, 75015 Paris, France.
| | - Maël Bessaud
- Institut Pasteur, Viral Populations and Pathogenesis Unit, CNRS UMR 3569, 75015 Paris, France.
| | - Bruno Blondel
- Institut Pasteur, Biology of Enteric Viruses Unit, 75015 Paris, France.
- INSERM U994, Institut National de la Santé et de la Recherche Médicale, 75015 Paris, France.
| | - Francis Delpeyroux
- Institut Pasteur, Biology of Enteric Viruses Unit, 75015 Paris, France.
- INSERM U994, Institut National de la Santé et de la Recherche Médicale, 75015 Paris, France.
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3
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Pagán I. The diversity, evolution and epidemiology of plant viruses: A phylogenetic view. INFECTION GENETICS AND EVOLUTION 2018; 65:187-199. [PMID: 30055330 DOI: 10.1016/j.meegid.2018.07.033] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 07/24/2018] [Accepted: 07/24/2018] [Indexed: 10/28/2022]
Abstract
During the past four decades, the scientific community has seen an exponential advance in the number, sophistication, and quality of molecular techniques and bioinformatics tools for the genetic characterization of plant virus populations. Predating these advances, the field of Phylogenetics has significantly contributed to understand important aspects of plant virus evolution. This review aims at summarizing the impact of Phylogenetics in the current knowledge on three major aspects of plant virus evolution that have benefited from the development of phylogenetic inference: (1) The identification and classification of plant virus diversity. (2) The mechanisms and forces shaping the evolution of plant virus populations. (3) The understanding of the interaction between plant virus evolution, epidemiology and ecology. The work discussed here highlights the important role of phylogenetic approaches in the study of the dynamics of plant virus populations.
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Affiliation(s)
- Israel Pagán
- Centro de Biotecnología y Genómica de Plantas UPM-INIA, E.T.S. Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid 28223, Spain.
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4
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Tepfer M, Jacquemond M, García-Arenal F. A critical evaluation of whether recombination in virus-resistant transgenic plants will lead to the emergence of novel viral diseases. THE NEW PHYTOLOGIST 2015; 207:536-41. [PMID: 25982848 DOI: 10.1111/nph.13358] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 02/10/2015] [Indexed: 05/07/2023]
Abstract
In the evaluation of the potential impacts of first-generation genetically modified (GM) crops, one of the most complex issues has been whether the expression of viral sequences would lead to the emergence of novel viruses, which could occur through recombination between transgene mRNA and that of an infecting non-target virus. Here, we examine this issue, focusing on Cucumber mosaic virus (CMV), which is a particularly pertinent choice, as it is both a major plant pathogen and also the virus with which this question has been studied in the most detail. Using recent results on recombination in CMV, we employ a novel framework giving particular prominence to the formulation of the risk hypothesis and to hypothesis testing via examination of the potential pathway to harm. This allows us to conclude with greater certainty that the likelihood of this potential harm, the emergence of novel viruses, is low.
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Affiliation(s)
- Mark Tepfer
- INRA UMR1318 Institut Jean-Pierre Bourgin, 78026, Versailles Cedex, France
- INRA UR407 Pathologie Végétale, 84143, Montfavet Cedex, France
| | | | - Fernando García-Arenal
- Centro de Biotecnología y Genómica de Plantas UPM-INIA and ETSI Agrónomos, Campus de Montegancedo, Universidad Politécnica de Madrid, 28223, Pozuelo de Alarcón, Spain
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5
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Marzano SYL, Hobbs HA, Nelson BD, Hartman GL, Eastburn DM, McCoppin NK, Domier LL. Transfection of Sclerotinia sclerotiorum with in vitro transcripts of a naturally occurring interspecific recombinant of Sclerotinia sclerotiorum hypovirus 2 significantly reduces virulence of the fungus. J Virol 2015; 89:5060-71. [PMID: 25694604 PMCID: PMC4403457 DOI: 10.1128/jvi.03199-14] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 02/16/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED A recombinant strain of Sclerotinia sclerotiorum hypovirus 2 (SsHV2) was identified from a North American Sclerotinia sclerotiorum isolate (328) from lettuce (Lactuca sativa L.) by high-throughput sequencing of total RNA. The 5'- and 3'-terminal regions of the genome were determined by rapid amplification of cDNA ends. The assembled nucleotide sequence was up to 92% identical to two recently reported SsHV2 strains but contained a deletion near its 5' terminus of more than 1.2 kb relative to the other SsHV2 strains and an insertion of 524 nucleotides (nt) that was distantly related to Valsa ceratosperma hypovirus 1. This suggests that the new isolate is a heterologous recombinant of SsHV2 with a yet-uncharacterized hypovirus. We named the new strain Sclerotinia sclerotiorum hypovirus 2 Lactuca (SsHV2L) and deposited the sequence in GenBank with accession number KF898354. Sclerotinia sclerotiorum isolate 328 was coinfected with a strain of Sclerotinia sclerotiorum endornavirus 1 and was debilitated compared to cultures of the same isolate that had been cured of virus infection by cycloheximide treatment and hyphal tipping. To determine whether SsHV2L alone could induce hypovirulence in S. sclerotiorum, a full-length cDNA of the 14,538-nt viral genome was cloned. Transcripts corresponding to the viral RNA were synthesized in vitro and transfected into a virus-free isolate of S. sclerotiorum, DK3. Isolate DK3 transfected with SsHV2L was hypovirulent on soybean and lettuce and exhibited delayed maturation of sclerotia relative to virus-free DK3, completing Koch's postulates for the association of hypovirulence with SsHV2L. IMPORTANCE A cosmopolitan fungus, Sclerotinia sclerotiorum infects more than 400 plant species and causes a plant disease known as white mold that produces significant yield losses in major crops annually. Mycoviruses have been used successfully to reduce losses caused by fungal plant pathogens, but definitive relationships between hypovirus infections and hypovirulence in S. sclerotiorum were lacking. By establishing a cause-and-effect relationship between Sclerotinia sclerotiorum hypovirus Lactuca (SsHV2L) infection and the reduction in host virulence, we showed direct evidence that hypoviruses have the potential to reduce the severity of white mold disease. In addition to intraspecific recombination, this study showed that recent interspecific recombination is an important factor shaping viral genomes. The construction of an infectious clone of SsHV2L allows future exploration of the interactions between SsHV2L and S. sclerotiorum, a widespread fungal pathogen of plants.
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Affiliation(s)
| | - Houston A Hobbs
- Department of Crop Sciences, University of Illinois, Urbana, Illinois, USA
| | - Berlin D Nelson
- Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, USA
| | - Glen L Hartman
- Department of Crop Sciences, University of Illinois, Urbana, Illinois, USA United States Department of Agriculture/Agricultural Research Service, Urbana, Illinois, USA
| | - Darin M Eastburn
- Department of Crop Sciences, University of Illinois, Urbana, Illinois, USA
| | - Nancy K McCoppin
- United States Department of Agriculture/Agricultural Research Service, Urbana, Illinois, USA
| | - Leslie L Domier
- Department of Crop Sciences, University of Illinois, Urbana, Illinois, USA United States Department of Agriculture/Agricultural Research Service, Urbana, Illinois, USA
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6
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Nouri S, Arevalo R, Falk BW, Groves RL. Genetic structure and molecular variability of Cucumber mosaic virus isolates in the United States. PLoS One 2014; 9:e96582. [PMID: 24801880 PMCID: PMC4012352 DOI: 10.1371/journal.pone.0096582] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 04/08/2014] [Indexed: 12/17/2022] Open
Abstract
Cucumber mosaic virus (CMV) has a worldwide distribution and the widest host range of any known plant virus. From 2000 to 2012, epidemics of CMV severely affected the production of snap bean (Phaseulos vulgaris L.) in the Midwest and Northeastern United States. Virus diversity leading to emergence of new strains is often considered a significant factor in virus epidemics. In addition to epidemics, new disease phenotypes arising from genetic exchanges or mutation can compromise effectiveness of plant disease management strategies. Here, we captured a snapshot of genetic variation of 32 CMV isolates collected from different regions of the U.S including new field as well as historic isolates. Nucleotide diversity (π) was low for U.S. CMV isolates. Sequence and phylogenetic analyses revealed that CMV subgroup I is predominant in the US and further showed that the CMV population is a mixture of subgroups IA and IB. Furthermore, phylogenetic analysis suggests likely reassortment between subgroups IA and IB within five CMV isolates. Based on phylogenetic and computational analysis, recombination between subgroups I and II as well as IA and IB in RNA 3 was detected. This is the first report of recombination between CMV subgroups I and II. Neutrality tests illustrated that negative selection was the major force operating upon the CMV genome, although some positively selected sites were detected for all encoded proteins. Together, these data suggest that different regions of the CMV genome are under different evolutionary constraints. These results also delineate composition of the CMV population in the US, and further suggest that recombination and reassortment among strain subgroups does occur but at a low frequency, and point towards CMV genomic regions that differ in types of selection pressure.
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Affiliation(s)
- Shahideh Nouri
- Department of Plant Pathology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Rafael Arevalo
- Department of Botany, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Bryce W. Falk
- Department of Plant Pathology, University of California Davis, Davis, California, United States of America
| | - Russell L. Groves
- Department of Entomology, University of Wisconsin, Madison, Wisconsin, United States of America
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7
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Miras M, Sempere RN, Kraft JJ, Miller WA, Aranda MA, Truniger V. Interfamilial recombination between viruses led to acquisition of a novel translation-enhancing RNA element that allows resistance breaking. THE NEW PHYTOLOGIST 2014; 202:233-246. [PMID: 24372390 PMCID: PMC4337425 DOI: 10.1111/nph.12650] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 11/19/2013] [Indexed: 05/04/2023]
Abstract
Many plant viruses depend on functional RNA elements, called 3'-UTR cap-independent translation enhancers (3'-CITEs), for translation of their RNAs. In this manuscript we provide direct proof for the existing hypothesis that 3'-CITEs are modular and transferable by recombination in nature, and that this is associated with an advantage for the created virus. By characterizing a newly identified Melon necrotic spot virus (MNSV; Tombusviridae) isolate, which is able to overcome eukaryotic translation initiation factor 4E (eIF4E)-mediated resistance, we found that it contains a 55 nucleotide insertion in its 3'-UTR. We provide strong evidence that this insertion was acquired by interfamilial recombination with the 3'-UTR of an Asiatic Cucurbit aphid-borne yellows virus (CABYV; Luteoviridae). By constructing chimeric viruses, we showed that this recombined sequence is responsible for resistance breaking. Analysis of the translational efficiency of reporter constructs showed that this sequence functions as a novel 3'-CITE in both resistant and susceptible plants, being essential for translation control in resistant plants. In conclusion, we showed that a recombination event between two clearly identified viruses from different families led to the transfer of exactly the sequence corresponding to a functional RNA element, giving rise to a new isolate with the capacity to infect an otherwise nonsusceptible host.
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Affiliation(s)
- Manuel Miras
- Centro de Edafología y Biología Aplicada del Segura (CEBAS), Consejo Superior de Investigaciones Científicas (CSIC), Apdo. Correos 164, 30100 Espinardo, Murcia, Spain
| | - Raquel N. Sempere
- Centro de Edafología y Biología Aplicada del Segura (CEBAS), Consejo Superior de Investigaciones Científicas (CSIC), Apdo. Correos 164, 30100 Espinardo, Murcia, Spain
| | - Jelena J. Kraft
- Department of Plant Pathology and Microbiology, Iowa State University, 351 Bessey Hall, Ames, IA 50011, USA
| | - W. Allen Miller
- Department of Plant Pathology and Microbiology, Iowa State University, 351 Bessey Hall, Ames, IA 50011, USA
| | - Miguel A. Aranda
- Centro de Edafología y Biología Aplicada del Segura (CEBAS), Consejo Superior de Investigaciones Científicas (CSIC), Apdo. Correos 164, 30100 Espinardo, Murcia, Spain
| | - Veronica Truniger
- Centro de Edafología y Biología Aplicada del Segura (CEBAS), Consejo Superior de Investigaciones Científicas (CSIC), Apdo. Correos 164, 30100 Espinardo, Murcia, Spain
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8
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Ni P, Vaughan RC, Tragesser B, Hoover H, Kao CC. The plant host can affect the encapsidation of brome mosaic virus (BMV) RNA: BMV virions are surprisingly heterogeneous. J Mol Biol 2014; 426:1061-76. [PMID: 24036424 PMCID: PMC3944473 DOI: 10.1016/j.jmb.2013.09.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 09/02/2013] [Accepted: 09/08/2013] [Indexed: 01/05/2023]
Abstract
Brome mosaic virus (BMV) packages its genomic and subgenomic RNAs into three separate viral particles. BMV purified from barley, wheat, and tobacco have distinct relative abundances of the encapsidated RNAs. We seek to identify the basis for the host-dependent differences in viral RNA encapsidation. Sequencing of the viral RNAs revealed recombination events in the 3' untranslated region of RNA1 of BMV purified from barley and wheat, but not from tobacco. However, the relative amounts of the BMV RNAs that accumulated in barley and wheat are similar and RNA accumulation is not sufficient to account for the difference in RNA encapsidation. Virions purified from barley and wheat were found to differ in their isoelectric points, resistance to proteolysis, and contacts between the capsid residues and the RNA. Mass spectrometric analyses revealed that virions from the three hosts had different post-translational modifications that should impact the physiochemical properties of the virions. Another major source of variation in RNA encapsidation was due to the purification of BMV particles to homogeneity. Highly enriched BMV present in lysates had a surprising range of sizes, buoyant densities, and distinct relative amounts of encapsidated RNAs. These results show that the encapsidated BMV RNAs reflect a combination of host effects on the physiochemical properties of the viral capsids and the enrichment of a subset of virions. The previously unexpected heterogeneity in BMV should influence the timing of the infection and also the host innate immune responses.
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Affiliation(s)
- Peng Ni
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
| | - Robert C Vaughan
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
| | - Brady Tragesser
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
| | - Haley Hoover
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
| | - C Cheng Kao
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA.
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9
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Tromas N, Zwart MP, Poulain M, Elena SF. Estimation of the in vivo recombination rate for a plant RNA virus. J Gen Virol 2013; 95:724-732. [PMID: 24362963 DOI: 10.1099/vir.0.060822-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Phylogenomic evidence suggested that recombination is an important evolutionary force for potyviruses, one of the larger families of plant RNA viruses. However, mixed-genotype potyvirus infections are marked by low levels of cellular coinfection, precluding template switching and recombination events between virus genotypes during genomic RNA replication. To reconcile these conflicting observations, we evaluated the in vivo recombination rate (rg) of Tobacco etch virus (TEV; genus Potyvirus, family Potyviridae) by coinfecting plants with pairs of genotypes marked with engineered restriction sites as neutral markers. The recombination rate was then estimated using two different approaches: (i) a classical approach that assumed recombination between marked genotypes can occur in the whole virus population, rendering an estimate of rg = 7.762 × 10(-8) recombination events per nucleotide site per generation, and (ii) an alternative method that assumed recombination between marked genotypes can occur only in coinfected cells, rendering a much higher estimate of rg = 3.427 × 10(-5) recombination events per nucleotide site per generation. This last estimate is similar to the TEV mutation rate, suggesting that recombination should be at least as important as point mutation in creating variability. Finally, we compared our mutation and recombination rate estimates to those reported for animal RNA viruses. Our analysis suggested that high recombination rates may be an unavoidable consequence of selection for fast replication at the cost of low fidelity.
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Affiliation(s)
- Nicolas Tromas
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-UPV, 46022 València, Spain
| | - Mark P Zwart
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-UPV, 46022 València, Spain
| | - Maïté Poulain
- Genoscreen, 1 Rue du Professeur Calmette, 59000 Lille, France
| | - Santiago F Elena
- The Santa Fe Institute, Santa Fe, NM 87501, USA.,Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-UPV, 46022 València, Spain
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10
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Morroni M, Jacquemond M, Tepfer M. Deep sequencing of recombinant virus populations in transgenic and nontransgenic plants infected with Cucumber mosaic virus. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:801-11. [PMID: 23530600 DOI: 10.1094/mpmi-02-13-0057-r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Recombination is a major source of virus variability, and the question of whether novel recombinant viruses would emerge in transgenic plants expressing viral sequences has been a biosafety issue. We describe the results of pyrosequencing the recombinant viral RNAs appearing in transgenic plants expressing the coat protein (CP) gene and 3' noncoding region of Cucumber mosaic virus RNA3, as well as in nontransgenic controls. The populations of recombinants in both transgenic and nontransgenic plants were similar to those previously described from Sanger sequencing but many more recombinant types were observed, including a novel class of large deletions removing all or nearly the entire CP gene. These results show that populations of recombinant viral genomes arising de novo can be characterized in detail by pyrosequencing, and confirm that the transgenic plants did not harbor novel recombinants of biosafety concern.
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Affiliation(s)
- Marco Morroni
- Plant Virology Group, ICGEB Biosafety Outstation, Ca' Tron di Roncade, I-31056, Italy
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11
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Pita JS, Roossinck MJ. Fixation of emerging interviral recombinants in cucumber mosaic virus populations. J Virol 2013; 87:1264-9. [PMID: 23115282 PMCID: PMC3554057 DOI: 10.1128/jvi.01892-12] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 10/23/2012] [Indexed: 11/20/2022] Open
Abstract
Interstrain recombinants were observed in the progenies of the Cucumber mosaic virus (CMV) reassortant L(1)L(2)F(3) containing RNAs 1 and 2 from LS-CMV and RNA 3 from Fny-CMV. We characterized these recombinants, and we found that their fixation was controlled by the nature of the replicating RNAs 1 and 2. We demonstrate that the 2b gene partially affects this fixation process, but only in the context of homologous RNAs 1 and 2.
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Affiliation(s)
- Justin S Pita
- Department of Plant Pathology and Environmental Biology, and The Huck Institutes of The Life Sciences, Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
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12
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Abstract
Cucumber mosaic virus (CMV) is an important virus because of its agricultural impact in the Mediterranean Basin and worldwide, and also as a model for understanding plant-virus interactions. This review focuses on those areas where most progress has been made over the past decade in our understanding of CMV. Clearly, a deep understanding of the role of the recently described CMV 2b gene in suppression of host RNA silencing and viral virulence is the most important discovery. These findings have had an impact well beyond the virus itself, as the 2b gene is an important tool in the studies of eukaryotic gene regulation. Protein 2b was shown to be involved in most of the steps of the virus cycle and to interfere with several basal host defenses. Progress has also been made concerning the mechanisms of virus replication and movement. However, only a few host proteins that interact with viral proteins have been identified, making this an area of research where major efforts are still needed. Another area where major advances have been made is CMV population genetics, where contrasting results were obtained. On the one hand, CMV was shown to be prone to recombination and to show high genetic diversity based on sequence data of different isolates. On the other hand, populations did not exhibit high genetic variability either within plants, or even in a field and the nearby wild plants. The situation was partially clarified with the finding that severe bottlenecks occur during both virus movement within a plant and transmission between plants. Finally, novel studies were undertaken to elucidate mechanisms leading to selection in virus population, according to the host or its environment, opening a new research area in plant-virus coevolution.
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13
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Fukuzawa N, Ishihara T, Itchoda N, Tabayashi N, Kataoka C, Masuta C, Matsumura T. Risk-managed production of bioactive recombinant proteins using a novel plant virus vector with a helper plant to complement viral systemic movement. PLANT BIOTECHNOLOGY JOURNAL 2011; 9:38-49. [PMID: 20492549 DOI: 10.1111/j.1467-7652.2010.00529.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A plant viral vector has the potential to efficiently produce recombinant proteins at a low cost in a short period. Although recombinant proteins can be also produced by transgenic plants, a plant viral vector, if available, may be more convenient when urgent scale-up in production is needed. However, it is difficult to use a viral vector in open fields because of the risk of escape to the environment. In this study, we constructed a novel viral vector system using a movement-defective Cucumber mosaic virus (CMV) vector, which is theoretically localized in the inoculated cells but infects systemically only with the aid of the transgenic helper plant that complements viral movement, diminishing the risk of viral proliferation. Interestingly, the helper plant systemically infected with the vector gave strong cross-protection against challenge inoculation with wild-type CMVs. Using CMV strains belonging to two discrete CMV groups (subgroups I and II), we also improved the system to prevent recombination between the vector and the transgene transcript in the helper plant. We here demonstrate the expression of an anti-dioxin single chain variable fragment (DxscFv) and interleukin-1 receptor antagonist (IL1-Ra) in Nicotiana benthamiana by this viral vector confinement system, which is applicable for many useful high-quality recombinant proteins.
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Affiliation(s)
- Noriho Fukuzawa
- Plant Molecular Technology Research Group, Research Institute of Genome-based Biofactory, National Institute of Advanced Industrial Science and Technology (AIST), Tsukisamuhigashi Toyohira-Ku, Sapporo, Japan
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14
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Sztuba-Solińska J, Urbanowicz A, Figlerowicz M, Bujarski JJ. RNA-RNA recombination in plant virus replication and evolution. ANNUAL REVIEW OF PHYTOPATHOLOGY 2011; 49:415-43. [PMID: 21529157 DOI: 10.1146/annurev-phyto-072910-095351] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
RNA-RNA recombination is one of the strongest forces shaping the genomes of plant RNA viruses. The detection of recombination is a challenging task that prompted the development of both in vitro and in vivo experimental systems. In the divided genome of Brome mosaic virus system, both inter- and intrasegmental crossovers are described. Other systems utilize satellite or defective interfering RNAs (DI-RNAs) of Turnip crinkle virus, Tomato bushy stunt virus, Cucumber necrosis virus, and Potato virus X. These assays identified the mechanistic details of the recombination process, revealing the role of RNA structure and proteins in the replicase-mediated copy-choice mechanism. In copy choice, the polymerase and the nascent RNA chain from which it is synthesized switch from one RNA template to another. RNA recombination was found to mediate the rearrangement of viral genes, the repair of deleterious mutations, and the acquisition of nonself sequences influencing the phylogenetics of viral taxa. The evidence for recombination, not only between related viruses but also among distantly related viruses, and even with host RNAs, suggests that plant viruses unabashedly test recombination with any genetic material at hand.
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Affiliation(s)
- Joanna Sztuba-Solińska
- Plant Molecular Biology Center, Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois 60115, USA
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15
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Asaoka R, Shimura H, Arai M, Masuta C. A progeny virus from a cucumovirus pseudorecombinant evolved to gain the ability to accumulate Its RNA-silencing suppressor leading to systemic infection in tobacco. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:332-9. [PMID: 20121454 DOI: 10.1094/mpmi-23-3-0332] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Two isolates of Tomato aspermy virus (TAV), V-TAV and C-TAV, can systemically infect Nicotiana benthamiana but only C-TAV can move systemically in N. tabacum. Any pseudorecombinants between the two strains could not move systemically in tobacco as efficiently as C-TAV. However, a pseudorecombinant consisting of RNAs 1 and 3 of V-TAV and RNA 2 of C-TAV (V1C2V3), which cannot infect tobacco systemically, generated progeny with a mutation in V1 and a recombination in C2 (V1(m)C2(r)V3), enabling the virus to move systemically. To avoid further mutation and recombination in the virus, we used Cucumber mosaic virus RNA3 (Y3) for subsequent experiments. Northern blot analyses showed that RNA4A, which encodes the 2b protein (2b), and RNA5 abundantly accumulated in V1(m)C2(r)Y3-infected tobacco. V1(m)C2(r)Y3 actually caused higher accumulation of 2b than did V1C2Y3 in Western blots, and overexpression of 2b by the PVX vector enabled V1C2Y3 to move systemically in tobacco, suggesting that 2b accumulation promotes viral systemic movement. Because RNA-silencing suppressor (RSS) activity of 2b was thought to be involved in systemic movement, we compared the RSS activity of 2b for the two TAV isolates; C-TAV 2b had stronger activity than did V-TAV 2b in tobacco in a transient protoplast assay. Our data also demonstrated that 2b and RNA5 play an important role in the evolution of members of genus Cucumovirus by generating mutant/recombinant viruses and viral systemic movement over RNA silencing.
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Affiliation(s)
- Ryota Asaoka
- Laboratory Of Cell Biology And Manipulation, Graduate School Of Agriculture, Hokkaido University, Sapporo, Japan
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16
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Morroni M, Thompson JR, Tepfer M. Analysis of recombination between viral RNAs and transgene mRNA under conditions of high selection pressure in favour of recombinants. J Gen Virol 2009; 90:2798-2807. [PMID: 19625460 DOI: 10.1099/vir.0.013771-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
One possible environmental risk related to the utilization of virus-resistant transgenic plants expressing viral sequences is the emergence of new viruses generated by recombination between the viral transgene mRNA and the RNA of an infecting virus. This hypothesis has been tested recently for cucumber mosaic virus (CMV) by comparing the recombinant populations in transgenic and non-transgenic plants under conditions of minimal selection pressure in favour of the recombinants. Equivalent populations were observed in transgenic and non-transgenic plants but, in both, there was a strongly dominant hotspot recombinant which was shown recently to be nonviable alone in planta, suggesting that its predominance could be reduced by applying an increased selection pressure in favour of viable recombinants. Partially disabled I17F-CMV mutants were created by engineering 6 nt deletions in five sites in the RNA3 3'-non-coding region (3'-NCR). One mutant was used to inoculate transgenic tobacco plants expressing the coat protein and 3'-NCR of R-CMV. A total of 22 different recombinant types were identified, of which 12 were, as expected, between the transgene mRNA and the mutated I17F-CMV RNA3, while 10 resulted from recombination between the mutated RNA3 and I17F-CMV RNA1. Twenty recombinants were of the aberrant type, while two, including the dominant one detected previously under conditions of minimal selection pressure, were homologous recombinants. All recombinants detected were very similar to ones observed in nature, suggesting that the deployment of transgenic lines similar to the one studied here would not lead to the emergence of new viruses.
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Affiliation(s)
- Marco Morroni
- Dipartimento di Produzione Vegetale, Università degli Studi di Milano, via Celoria 2, 20133 Milano, Italy
- Plant Virology Group, ICGEB Biosafety Outstation, Via Piovega 23, 31056 Ca' Tron di Roncade, Italy
| | - Jeremy R Thompson
- Plant Virology Group, ICGEB Biosafety Outstation, Via Piovega 23, 31056 Ca' Tron di Roncade, Italy
| | - Mark Tepfer
- Plant Virology Group, ICGEB Biosafety Outstation, Via Piovega 23, 31056 Ca' Tron di Roncade, Italy
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17
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Thompson JR, Tepfer M. The 3' untranslated region of cucumber mosaic virus (CMV) subgroup II RNA3 arose by interspecific recombination between CMV and tomato aspermy virus. J Gen Virol 2009; 90:2293-8. [DOI: 10.1099/vir.0.011452-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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18
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Shi BJ, Symons RH, Palukaitis P. Stability and competitiveness of interviral recombinant RNAs derived from a chimeric cucumovirus. Virus Res 2009; 140:216-21. [PMID: 19063925 DOI: 10.1016/j.virusres.2008.11.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 10/01/2008] [Accepted: 11/10/2008] [Indexed: 11/17/2022]
Abstract
We previously described interviral recombinant RNAs derived from a chimeric virus having RNAs 1 and 2 of cucumber mosaic virus (CMV) with RNA 3 from the related tomato aspermy virus (TAV) and the 2b gene from either TAV or another strain of CMV. Here, we show that these interviral recombinant RNAs 3 were stable in the infected plants and could co-exist with their wild-type parental viral RNAs in the same plants, but their de novo generations were inhibited in the presence of the wild-type parental viral RNAs. The recombinant viral genomes did not prevent the replication of other viral RNAs or vice versa, but one of the interviral recombinant viruses induced different symptoms in Physalis floridana from those induced by the parental chimeric virus without the interviral RNA 3 recombinant. Factors such as the nature of the 2b gene and/or the presence or absence of competing wild-type parental RNAs influenced the generation of the recombinant RNAs described. Our data provide additional mechanistic insight into generation, stabilization and competition of recombinant viral RNA in infected host plants.
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Affiliation(s)
- Bu-Jun Shi
- Australian Centre for Plant Functional Genomics, University of Adelaide, Glen Osmond, SA 5064, Australia
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19
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de Wispelaere M, Rao ALN. Production of cucumber mosaic virus RNA5 and its role in recombination. Virology 2008; 384:179-91. [PMID: 19059620 DOI: 10.1016/j.virol.2008.10.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Revised: 10/04/2008] [Accepted: 10/12/2008] [Indexed: 10/21/2022]
Abstract
Cucumber Mosaic Virus (CMV) is a plant infecting tripartite positive-strand RNA virus. In addition to three genomic and two known subgenomic RNAs, CMV strains of subgroup II (e.g. Q-CMV), but not subgroup I (e.g. Fny-CMV), produce and package a redundant RNA5 encompassing the 3' 304-307 nucleotides of RNAs 2 and 3. The mechanism regulating RNA5 production and its role in CMV life cycle is unknown. In this study, transient expression of Q2 or Q3 by agroinfiltration into Nicotiana benthamiana plants resulted in efficient accumulation of RNA5 suggesting that its production is independent of CMV replication. Deletion and point mutations engineered into a highly conserved region (Box1) adjacent to the 5' end of RNA5 identified sequences required for its efficient production. An experimental system, involving a chimera of Q3 (Q3B3) characterized by having a 3' tRNA-like structure (3'TLS) from Brome mosaic virus (BMV) and RNA5 defective variants of Q1 (Q1Delta), Q2 (Q2Delta) and Q3B3 (Q3DeltaB3), was used to evaluate in vivo the contribution of RNA5 in promoting RNA recombination. Generation of precise homologous recombinants was strictly dependent on sequence identity. When both parental RNAs carried the Box1, recombination occurred preferentially within the Box1. In contrast, generation of non-homologous recombinants occurred only when Q1 and Q2 were competent to produce RNA5. A mechanistic model explaining the functional role played by the RNA5 in generating CMV recombinants was presented.
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Affiliation(s)
- Melissanne de Wispelaere
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521-0122, USA
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20
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Codoñer FM, Elena SF. The promiscuous evolutionary history of the family Bromoviridae. J Gen Virol 2008; 89:1739-1747. [DOI: 10.1099/vir.0.2008/000166-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recombination and segment reassortment are important contributors to the standing genetic variation of RNA viruses and are often involved in the genesis of new, emerging viruses. This study explored the role played by these two processes in the evolutionary radiation of the plant virus family Bromoviridae. The evolutionary history of this family has been explored previously using standard molecular phylogenetic methods, but incongruences have been found among the trees inferred from different gene sequences. This would not be surprising if RNA exchange was a common event, as it is well known that recombination and reassortment of genomes are poorly described by standard phylogenetic methods. In an attempt to reconcile these discrepancies, this study first explored the extent of segment reassortment and found that it was common at the origin of the bromoviruses and cucumoviruses and at least at the origin of alfalfa mosaic virus, American plum line pattern virus and citrus leaf rugose virus. Secondly, recombination analyses were performed on each of the three genomic RNAs and it was found that recombination was very common in members of the genera Bromovirus, Cucumovirus and Ilarvirus. Several cases of recombination involving species from different genera were also identified. Finally, a phylogenetic network was constructed reflecting these genetic exchanges. The network confirmed the taxonomic status of the different genera within the family, despite the phylogenetic noise introduced by genetic exchange.
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Affiliation(s)
| | - Santiago F. Elena
- Instituto de Biología Molecular y Celular de Plantas, CSIC-UPV, Valencia, Spain
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21
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Nucleotide sequence analysis of peanut stunt virus Rp strain suggests the role of homologous recombination in cucumovirus evolution. Arch Virol 2008; 153:1373-7. [PMID: 18523838 DOI: 10.1007/s00705-008-0120-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Accepted: 05/19/2008] [Indexed: 10/22/2022]
Abstract
The complete nucleotide (nt) sequence of peanut stunt virus Robinia strain (PSV-Rp) was determined and compared to other PSV strains and to representatives of the genus Cucumovirus. Nt sequence comparison showed 74.1-84.6% identity with the known PSV strains. Phylogenetic analysis revealed the different origin of the two genes encoded by RNA3. While the 3a gene clustered with PSV-W, the coat protein gene clustered with PSV-Mi. Recombination breakpoint analysis revealed two recombination points on RNA3. Based on these results, the establishment of a fourth PSV subgroup is proposed. This work revealed that homologous recombination occurred during the evolution of PSV.
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22
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Evaluation of potential risks associated with recombination in transgenic plants expressing viral sequences. J Gen Virol 2008; 89:327-335. [DOI: 10.1099/vir.0.83339-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Virus-resistant transgenic plants have been created primarily through the expression of viral sequences. It has been hypothesized that recombination between the viral transgene mRNA and the RNA of an infecting virus could generate novel viruses. As mRNA/viral RNA recombination can occur in virus-resistant transgenic plants, the key to testing this risk hypothesis is to compare the populations of recombinant viruses generated in transgenic and non-transgenic plants. This has been done with two cucumoviral systems, involving either two strains of cucumber mosaic virus (CMV), or CMV and the related tomato aspermy virus (TAV). Although the distribution of the sites of recombination in the CMV/CMV and TAV/CMV systems was quite different, equivalent populations of recombinant viruses were observed in both cases. These results constitute the first comparison of the populations of recombinants in transgenic and non-transgenic plants, and suggest that there is little risk of emergence of recombinant viruses in these plants, other than those that could emerge in non-transgenic plants.
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23
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Shi BJ, Symons RH, Palukaitis P. The cucumovirus 2b gene drives selection of inter-viral recombinants affecting the crossover site, the acceptor RNA and the rate of selection. Nucleic Acids Res 2007; 36:1057-71. [PMID: 18086712 PMCID: PMC2275080 DOI: 10.1093/nar/gkm1036] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RNA–RNA recombination is an important pathway in virus evolution and has been described for many viruses. However, the factors driving recombination or promoting the selection of recombinants are still unclear. Here, we show that the small movement protein (2b) was able to promote selection of RNA 1/2–RNA 3 recombinants within a chimeric virus having RNAs 1 and 2 from cucumber mosaic virus, and RNA 3 from the related tomato aspermy virus, along with heterologous 2b genes. The source of the 2b also determined the selection of the acceptor RNA and the crossover site, as well as affecting the rate of selection of the recombinant RNAs. The nature of the RNA 3 also influenced the selection of the recombinant RNAs. A 163-nt tandem repeat in RNA 3 significantly affected the rate of selection of the recombinant RNA, while a single nucleotide within the repeat affected the crossover site. The recombination occurred in a non-random manner, involved no intermediates and probably was generated via a copy-choice mechanism during (+) strand RNA synthesis.
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Affiliation(s)
- Bu-Jun Shi
- Australian Centre for Plant Functional Genomics, University of Adelaide, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, SA 5064, Australia.
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24
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Pierrugues O, Guilbaud L, Fernandez-Delmond I, Fabre F, Tepfer M, Jacquemond M. Biological properties and relative fitness of inter-subgroup cucumber mosaic virus RNA 3 recombinants produced in vitro. J Gen Virol 2007; 88:2852-2861. [PMID: 17872540 DOI: 10.1099/vir.0.83077-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In vitro reverse transcription of a mixture of total RNA from plants infected with the I17F or R strains of cucumber mosaic virus (CMV), representative of subgroups IA and II, respectively, results in viral cDNA populations including rare recombinant RNA 3 molecules, some of which also have point mutations. The biological properties of 17 recombinants in the capsid gene or the 3' non-coding region of RNA 3 were evaluated when associated with I17F RNAs 1 and 2. Six viruses displayed deficiencies (non-viability, deficiencies for movement and/or replication, delayed infection, loss of aphid transmissibility). Nine induced symptoms close to those of I17F-CMV on tobacco and pepper plants. All recombinants bearing the movement protein (MP) of R-CMV and part or most of the capsid protein (CP) of I17F-CMV, as well as the recombinant created in vitro by exchanging the corresponding open reading frames, also induced filiformism on tobacco, but induced only faint symptoms on melon. Two recombinants induced atypically severe symptoms on both tobacco and pepper. Most of the recombinants generally accumulated to lower levels than the wild-type I17F strain in tobacco. Three recombinants, however, including one responsible for severe symptoms, accumulated to generally higher levels than I17F-CMV. When two of these were tested in co-infection experiments with I17F RNA 3, they proved to be poorly competitive, suggesting that they would be unlikely to emerge in the field.
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Affiliation(s)
- Olivier Pierrugues
- INRA, UR407, Station de Pathologie Végétale, BP 94, 84143 Montfavet cedex, France
| | - Laurent Guilbaud
- INRA, UR407, Station de Pathologie Végétale, BP 94, 84143 Montfavet cedex, France
| | | | - Frédéric Fabre
- INRA, UR407, Station de Pathologie Végétale, BP 94, 84143 Montfavet cedex, France
| | - Mark Tepfer
- Plant Virology Group, ICGEB Biosafety Outstation, Via Piovega 23, 31056 Ca' Tron di Roncade, Italy
- INRA, UR501, Laboratoire de Biologie Cellulaire, 78026 Versailles cedex, France
| | - Mireille Jacquemond
- INRA, UR407, Station de Pathologie Végétale, BP 94, 84143 Montfavet cedex, France
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25
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Zhang C, Gu H, Ghabrial SA. Molecular Characterization of Naturally Occurring RNA1 Recombinants of the Comovirus Bean pod mottle virus. PHYTOPATHOLOGY 2007; 97:1255-1262. [PMID: 18943683 DOI: 10.1094/phyto-97-10-1255] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
ABSTRACT The Bean pod mottle virus, a member of the genus Comovirus, has a bipartite genome consisting of RNA1 and RNA2. We previously reported the occurrence in nature of two distinct subgroups of BPMV strains (subgroups I and II), as well as reassortants between the two subgroups. Here, we report on the isolation and molecular characterization of RNA1 recombinants from soybean plants infected with the partial diploid reassortant strain IL-Cb1, which induces very severe symptoms on soybean. cDNA cloning and sequencing of RNA1 from strain IL-Cb1 revealed the presence of chimeric and mosaic recombinant RNA1s. The full-length mosaic and chimeric recombinant RNA1s were infectious and induced mild symptoms on soybean. Although the recombinant RNA1 accumulated to high levels in the absence of wild-type RNA1, its accumulation level was low in mixed infections with wild-type RNA1. Recombinant RNA1 molecules with similar structures to the naturally occurring recombinant RNA1s were generated in soybean after four passages following inoculation with RNA1 transcripts derived from cDNAs of two distinct strains. This suggests that recombination events are frequent and that a recombination hot spot exists. Sequence analysis of the recombination region showed that it has AU-rich sequences characteristic of recombination hot spots.
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26
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Ohshima K, Tomitaka Y, Wood JT, Minematsu Y, Kajiyama H, Tomimura K, Gibbs AJ. Patterns of recombination in turnip mosaic virus genomic sequences indicate hotspots of recombination. J Gen Virol 2007; 88:298-315. [PMID: 17170463 DOI: 10.1099/vir.0.82335-0] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Potyviruses have variable single-stranded RNA genomes and many show clear evidence of recombination. This report studied the distribution of recombination sites in the genomes of 92 isolates of the potyvirus Turnip mosaic virus (TuMV); 42 came from the international gene sequence databases and an additional 50 complete genomic sequences were generated from field samples collected in Europe and Asia. The sequences were examined for evidence of recombination using seven different sequence comparison methods and the exact position of each site was confirmed by sequence composition analysis. Recombination sites were found throughout the genomes, except in the small 6K1 protein gene, and only 24 of the genomes (26%) showed no evidence of recombination. Statistically significant clusters of recombination sites were found in the P1 gene and in the CI/6K2/VPg gene region. Most recombination sites were bordered by an upstream (5') region of GC-rich and downstream (3') region of AU-rich sequence of a similar length. Correlations between the presence and type of recombination site and provenance, host type and phylogenetic relationships are discussed, as is the role of recombination in TuMV evolution.
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Affiliation(s)
- Kazusato Ohshima
- Laboratory of Plant Virology, Faculty of Agriculture, Saga University, Saga 840-8502, Japan
| | - Yasuhiro Tomitaka
- Laboratory of Plant Virology, Faculty of Agriculture, Saga University, Saga 840-8502, Japan
| | - Jeffery T Wood
- Statistical Consulting Unit, Graduate School, Australian National University, Canberra, ACT 0200, Australia
| | - Yoshiteru Minematsu
- Laboratory of Plant Virology, Faculty of Agriculture, Saga University, Saga 840-8502, Japan
| | - Hiromi Kajiyama
- Laboratory of Plant Virology, Faculty of Agriculture, Saga University, Saga 840-8502, Japan
| | - Kenta Tomimura
- Laboratory of Plant Virology, Faculty of Agriculture, Saga University, Saga 840-8502, Japan
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27
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Xi D, Lan L, Wang J, Xu W, Xiang B, Lin H. Variation analysis of two cucumber mosaic viruses and their associated satellite RNAs from sugar beet in China. Virus Genes 2007; 33:293-8. [PMID: 16991000 DOI: 10.1007/s11262-006-0068-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2005] [Accepted: 01/15/2006] [Indexed: 11/26/2022]
Abstract
Two cucumber mosaic virus (CMV) isolates XJ1 and XJ2 were obtained from sugar beet showing yellow mosaic symptom in Shihezi, Xinjiang Uigur municipality of China. The coat protein gene of the two CMV isolates and their associated satellite RNAs were amplified by reverse transcriptase polymerase chain reaction (RT-PCR) and were cloned and sequenced. Comparison of CP gene sequences showed that XJ1 and XJ2 have the highest sequence identity with that of CMV-Danshen (97.8%) and CMV-SD (98.7%), respectively. Two types of satellite RNAs (XJs1 and XJs2) were found to be associated with the two CMV isolates consisting of 384 nucleotides and 336 nucleotides, respectively. Sequence comparisons revealed that XJs1 and XJs2 were most closely related to CS2-sat and CS1-sat, respectively, with 98.9% and 98.5% nucleotide sequence identity. Phylogenetic analysis of nucleotide sequence and deduced amino acid sequence of coat protein gene revealed that XJ1 and XJ2 belong to subgroup IB but there exist some variation between them. Parallel analyses of nucleotide sequence of XJsl and XJs2 suggested that these two satellite RNAs probably originated from China.
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Affiliation(s)
- Dehui Xi
- Key laboratory of Bio-resources and Eco-envirorment, Ministry of Education, College of life science, Sichuan University, Chengdu , 610064, China
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28
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Moury B, Desbiez C, Jacquemond M, Lecoq H. Genetic diversity of plant virus populations: towards hypothesis testing in molecular epidemiology. Adv Virus Res 2006; 67:49-87. [PMID: 17027677 DOI: 10.1016/s0065-3527(06)67002-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- B Moury
- INRA Avignon, Station de Pathologie Végétale, Domaine St Maurice BP94 84143 Montfavet cedex, France
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29
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Choi BK, Koo JM, Ahn HJ, Yum HJ, Choi CW, Ryu KH, Chen P, Tolin SA. Emergence of Rsv-resistance breaking Soybean mosaic virus isolates from Korean soybean cultivars. Virus Res 2005; 112:42-51. [PMID: 15869819 DOI: 10.1016/j.virusres.2005.03.020] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2004] [Revised: 03/09/2005] [Accepted: 03/09/2005] [Indexed: 11/28/2022]
Abstract
Twelve Rsv resistance-breaking (RB) isolates of Soybean mosaic virus (SMV) were obtained from field-grown soybean plants showing mosaic symptoms and subsequently examined biologically and molecularly. All of these RB isolates were identified as SMV based on serological and infectivity assays, and the amplification of P1 gene products by reverse transcription-polymerase chain reaction (RT-PCR). Differential soybean cultivars, lines or accessions Lee 68 (rsv), PI 96983, York, Marshall, Ogden, Kwanggyo, Suweon 97 (Rsv1 alleles), L29 (Rsv3), and V94-5152 (Rsv4), following inoculation with each RB isolate, showed similar systemic symptoms suggesting that these RB isolates can overcome Rsv resistance at three loci. To differentiate the 12 RB isolates molecularly, the P1 coding region for each isolate was amplified, cloned, sequenced and compared to known SMV strains. The P1 region from the RB isolates shared 86-90% and 90-99% similarities in amino acid (aa) and nucleotide sequence, respectively, with known SMV strains. Comparison of aa sequences indicated that these RB isolates are newly emerging isolates capable of breaking Rsv resistance. Phylogenetic analysis further suggested that the RB isolates can be classified as three major types. However, recombination was not observed within the coding region of P1 protein among the types. This is the first report on the emergence of SMV isolates capable of overcoming all of the known resistance alleles at the Rsv1 locus, as well as distinct resistance genes at Rsv3 and Rsv4.
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Affiliation(s)
- B K Choi
- Department of Biology and Medicinal Science, Pai Chai University, Daejeon 302-735, Republic of Korea
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Urbanowicz A, Alejska M, Formanowicz P, Blazewicz J, Figlerowicz M, Bujarski JJ. Homologous crossovers among molecules of brome mosaic bromovirus RNA1 or RNA2 segments in vivo. J Virol 2005; 79:5732-42. [PMID: 15827188 PMCID: PMC1082739 DOI: 10.1128/jvi.79.9.5732-5742.2005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previously we demonstrated frequent homologous crossovers among molecules of the RNA3 segment in the tripartite brome mosaic bromovirus (BMV) RNA genome (A. Bruyere, M. Wantroba, S. Flasinski, A. Dzianott, and J. J. Bujarski, J. Virol. 74:4214-4219, 2000). To further our knowledge about mechanisms of viral RNA genome variability, in this paper we have studied homologous recombination in BMV RNA1 and RNA2 components during infection. We have found that basal RNA-RNA crossovers could occur within coding regions of both RNAs, although recombination frequencies slightly varied at different RNA sections. In all cases, the frequencies were much lower than the rate observed for the intercistronic recombination hot spot in BMV RNA3. Probability calculations accounted for at least one homologous crossover per RNA molecule per replication cycle. In addition, we have demonstrated an efficient repair of mutations within the conserved 3' and 5' noncoding regions, most likely due to error-prone BMV RNA replication. Overall, our data verify that homologous crossovers are common events a during virus life cycle, and we discuss their importance for viral RNA genetics.
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Affiliation(s)
- Anna Urbanowicz
- Department of Biological Sciences, Montgomery Hall, Northern Illinois University, De Kalb, IL 60015, USA
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Bonnet J, Fraile A, Sacristán S, Malpica JM, García-Arenal F. Role of recombination in the evolution of natural populations of Cucumber mosaic virus, a tripartite RNA plant virus. Virology 2005; 332:359-68. [PMID: 15661167 DOI: 10.1016/j.virol.2004.11.017] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2004] [Revised: 10/06/2004] [Accepted: 11/16/2004] [Indexed: 11/27/2022]
Abstract
The role of recombination in the evolution of Cucumber mosaic virus (CMV) was analyzed in a collection of Spanish isolates from 1989 to 2002. Isolates were characterized by ribonuclease protection assay using six RNA probes, two for each of the three genomic RNAs, which allowed the identification of the analyzed regions as belonging to CMV isolates in subgroups IA, IB, and II. Most isolates belonged to subgroups IA (64%) and IB (12%), 5% were reassortants among subgroups IA, IB, or II, and 17% were recombinants between these groups. Recombinants at RNA3 were significantly more frequent than recombinants at RNAs 1 and 2. One IB-IA recombinant RNA3 was as frequent in central Spain as the IA RNA3. The genetic structure of the virus population suggested that reassortants and most recombinant genotypes were selected against and was consistent with a higher biological cost of reassortment than recombination. Data also suggest that recombinants that encode hybrid proteins are at a higher disadvantage than recombinants that exchange whole ORFs.
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Affiliation(s)
- Julien Bonnet
- Departamento de Biotecnología, E.T.S.I. Agrónomos, Universidad Politécnica de Madrid, 28040 Madrid, Spain
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Tomimura K, Spak J, Katis N, Jenner CE, Walsh JA, Gibbs AJ, Ohshima K. Comparisons of the genetic structure of populations of Turnip mosaic virus in West and East Eurasia. Virology 2005; 330:408-23. [PMID: 15567435 DOI: 10.1016/j.virol.2004.09.040] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2004] [Revised: 09/15/2004] [Accepted: 09/28/2004] [Indexed: 11/23/2022]
Abstract
The genetic structure of populations of Turnip mosaic virus in Eurasia was assessed by making host range and gene sequence comparisons of 142 isolates. Most isolates collected in West Eurasia infected Brassica plants whereas those from East Eurasia infected both Brassica and Raphanus plants. Analyses of recombination sites (RSs) in five regions of the genome (one third of the full sequence) showed that the protein 1 (P1 gene) had recombined more frequently than the other gene regions in both subpopulations, but that the RSs were located in different parts of the genomes of the subpopulations. Estimates of nucleotide diversity showed that the West Eurasian subpopulation was more diverse than the East Eurasian subpopulation, but the Asian-BR group of the genes from the latter subpopulation had a greater nonsynonymous/synonymous substitution ratio, especially in the P1, viral genome-linked protein (VPg) and nuclear inclusion a proteinase (NIa-Pro) genes. These subpopulations seem to have evolved independently from the ancestral European population, and their genetic structure probably reflects founder effects.
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Affiliation(s)
- Kenta Tomimura
- Laboratory of Plant Virology, Faculty of Agriculture, Saga University, Saga 840-8502, Japan
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de Wispelaere M, Gaubert S, Trouilloud S, Belin C, Tepfer M. A map of the diversity of RNA3 recombinants appearing in plants infected with Cucumber mosaic virus and Tomato aspermy virus. Virology 2005; 331:117-27. [PMID: 15582658 DOI: 10.1016/j.virol.2004.10.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 08/06/2004] [Accepted: 10/08/2004] [Indexed: 10/26/2022]
Abstract
In order to better understand the role of recombination in creating the diversity of viral genomes that is acted on by selection, we have studied in detail the population of recombinant RNA3 molecules occurring in tobacco plants coinfected with wild-type strains of cucumber mosaic virus (CMV) and tomato aspermy virus (TAV) under conditions of minimal selection pressure. Recombinant RNA3s were observed in 9.6% of the samples. Precise homologous recombination predominated since it was observed at 28 different sites, primarily in six hot spots. Imprecise homologous recombination was observed at two sites, particularly within a GU repeat in the 5' noncoding region. Seven of the eight aberrant homologous recombination sites observed were clustered in the 3' noncoding region. These results have implications on the role of recombination in host adaptation and virus evolution. They also provide essential baseline information for understanding the potential epidemiological impact of recombination in transgenic plants expressing viral sequences.
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Tan Z, Wada Y, Chen J, Ohshima K. Inter- and intralineage recombinants are common in natural populations of Turnip mosaic virus. J Gen Virol 2004; 85:2683-2696. [PMID: 15302962 DOI: 10.1099/vir.0.80124-0] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A recombination map of the genome of Turnip mosaic virus (TuMV) was assembled using data from 19 complete genomic sequences, previously reported, and a composite sample of three regions of the genome, one-third in total, of a representative Asia-wide collection of 70 isolates. Thus, a total of 89 isolates of worldwide origin was analysed for recombinants. Eighteen recombination sites were found spaced throughout the 5′ two-thirds of the genome, but there were only two in the 3′ one-third; thus, 24 and 35 % of the P1 and NIa-VPg gene sequences examined were recombinants, whereas only 1 % of the corresponding NIa-Pro and CP gene sequences were recombinants. Recombinants with parents from the same or from different lineages were found, and some recombination sites characterized particular lineages. Most of the strain BR recombinants belonged to the Asian-BR group, as defined previously, and it was concluded that this lineage resulted from a recent migration, whereas many of the strain B recombinants from Asia fell into the world-B group. Again, a large proportion of isolates in this group were recombinants. Some recombination sites were found only in particular lineages, and hence seemed more likely to be the surviving progeny from single recombinational events, rather than the progeny of multiple events occurring at recombination hotspots. It seems that the presence of recombination sites, as well as sequence similarities, may be used to trace the migration and evolution of TuMV.
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Affiliation(s)
- Zhongyang Tan
- Laboratory of Plant Virology, Faculty of Agriculture, Saga University, Saga 840-8502, Japan
| | - Yasuhiko Wada
- BioInfomatics Research Division, Japan Science and Technology Corporation, Tokyo 102-0081, Japan
- Laboratory of Animal Production and Management, Faculty of Agriculture, Saga University, Saga 840-8502, Japan
| | - Jishuang Chen
- Institute of Bioengineering, Zhejiang University of Science and Technology, Hangzhou Xiasha 310018, PR China
| | - Kazusato Ohshima
- Laboratory of Plant Virology, Faculty of Agriculture, Saga University, Saga 840-8502, Japan
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Lin HX, Rubio L, Smythe AB, Falk BW. Molecular population genetics of Cucumber mosaic virus in California: evidence for founder effects and reassortment. J Virol 2004; 78:6666-75. [PMID: 15163757 PMCID: PMC416521 DOI: 10.1128/jvi.78.12.6666-6675.2004] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2003] [Accepted: 02/18/2004] [Indexed: 11/20/2022] Open
Abstract
The structure and genetic diversity of a California Cucumber mosaic virus (CMV) population was assessed by single-strand conformation polymorphism and nucleotide sequence analyses of genomic regions 2b, CP, MP, and the 3' nontranslated region of RNA3. The California CMV population exhibited low genetic diversity and was composed of one to three predominant haplotypes and a large number of minor haplotypes for specific genomic regions. Extremely low diversity and close evolutionary relationships among isolates in a subpopulation suggested that founder effects might play a role in shaping the genetic structure. Phylogenetic analysis indicated a naturally occurring reassortant between subgroup IA and IB isolates and potential reassortants between subgroup IA isolates, suggesting that genetic exchange by reassortment contributed to the evolution of the California CMV population. Analysis of various population genetics parameters and distribution of synonymous and nonsynonymous mutations revealed that different coding regions and even different parts of coding regions were under different evolutionary constraints, including a short region of the 2b gene for which evidence suggests possible positive selection.
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Affiliation(s)
- Han-Xin Lin
- Department of Plant Pathology, University of California-Davis, 1 Shields Avenue, Davis, CA 95616, USA
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Abstract
Research on the molecular biology of cucumoviruses and their plant-virus interactions has been very extensive in the last decade. Cucumovirus genome structures have been analyzed, giving new insights into their genetic variability, evolution, and taxonomy. A new viral gene has been discovered, and its role in promoting virus infection has been delineated. The localization and various functions of each viral-encoded gene product have been established. The particle structures of Cucumber mosaic virus (CMV) and Tomato aspermy virus have been determined. Pathogenicity domains have been mapped, and barriers to virus infection have been localized. The movement pathways of the viruses in some hosts have been discerned, and viral mutants affecting the movement processes have been identified. Host responses to viral infection have been characterized, both temporally and spatially. Progress has been made in determining the mechanisms of replication, gene expression, and transmission of CMV. The pathogenicity determinants of various satellite RNAs have been characterized, and the importance of secondary structure in satellite RNA-mediated interactions has been recognized. Novel plant genes specifying resistance to infection by CMV have been identified. In some cases, these genes have been mapped, and one resistance gene to CMV has been isolated and characterized. Pathogen-derived resistance has been demonstrated against CMV using various segments of the CMV genome, and the mechanisms of some of these forms of resistances have been analyzed. Finally, the nature of synergistic interactions between CMV and other viruses has been characterized. This review highlights these various achievements in the context of the previous work on the biology of cucumoviruses and their interactions with plants.
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Affiliation(s)
- Peter Palukaitis
- Gene Expression Programme, Scottish Crop Research Institute, Invergowrie, Dundee, DD2 5DA, United Kingdom
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Abstract
RNA viruses are the most common viruses of plants, and the evolution of these viruses has been studied both experimentally and phylogenetically. The basic molecular mechanisms for plant virus evolution are similar to those of other viruses, with some notable exceptions. Recent advances include new insights into the origins of plant viruses, analyses of quasispecies and mutation frequencies, population studies on field isolates and practical studies on the importance of virus evolution to agriculture.
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Affiliation(s)
- Marilyn J Roossinck
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73402, USA.
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Tomimura K, Gibbs AJ, Jenner CE, Walsh JA, Ohshima K. The phylogeny of Turnip mosaic virus; comparisons of 38 genomic sequences reveal a Eurasian origin and a recent 'emergence' in east Asia. Mol Ecol 2003; 12:2099-111. [PMID: 12859632 DOI: 10.1046/j.1365-294x.2003.01881.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The genomes of a representative world-wide collection of 32 Turnip mosaic virus (TuMV) isolates were sequenced and these, together with six previously reported sequences, were analysed. At least one-fifth of the sequences were recombinant. In phylogenetic analyses, using genomic sequences of Japanese yam mosaic virus as an outgroup, the TuMV sequences that did not show clear recombination formed a monophyletic group with four well-supported lineages. These groupings correlated with differences in pathogenicity and provenance; the sister group to all others was of Eurasian B-strain isolates from nonbrassicas, and probably represents the ancestral TuMV population, and the most recently 'emerged' branch of the population was probably that of the BR-strain isolates found only in east Asia. Eight isolates, all from east Asia, were clear recombinants, probably the progeny of recent recombination events, whereas a similar number, from other parts of the world, were seemingly older recombinants. This difference indicates that the presence of clear recombinants in a subpopulation may be a molecular signature of a recent 'emergence'.
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Affiliation(s)
- K Tomimura
- Laboratory of Plant Virology, Faculty of Agriculture, Saga University, Saga 840-8502, Japan
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Suzuki M, Hibi T, Masuta C. RNA recombination between cucumoviruses: possible role of predicted stem-loop structures and an internal subgenomic promoter-like motif. Virology 2003; 306:77-86. [PMID: 12620800 DOI: 10.1016/s0042-6822(02)00050-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We previously analyzed hybrids of Cucumber mosaic virus (CMV) and Tomato aspermy virus (TAV) that contained CMV RNA2 with the 3'-terminal sequence from TAV RNA2. In this article, we scrutinized the RNA3 molecules in these hybrid viruses by Northern hybridization and RT-PCR and found some recombinant CMV RNA3 molecules and various recombinant RNA4 molecules whose 3'-termini were derived from TAV RNA1 or 2. Sequence analyses revealed that most of the crossover sites for recombination were located near putative stem-loop structures and an internal subgenomic promoter-like motif. We inoculated in vitro transcripts synthesized from cDNA clones of the recombinant RNA3 onto N. benthamiana along with either CMV RNA1 and 2 or TAV RNA1 and 2. Although all of the hybrids were infectious, many sequence deletions and nucleotide substitutions were found when RNA1 and 2 from TAV were used, which suggests that fidelity of TAV replicase was lower than that of CMV replicase. The possible role of secondary structures and an internal subgenomic promoter-like motif in RNA recombination is discussed.
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Affiliation(s)
- Masashi Suzuki
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 113-8657, Tokyo, Japan.
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