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Roy A, Grinstead S, Leon Martínez G, Pinzón JCC, Nunziata SO, Padmanabhan C, Hammond J. Meta-Transcriptomic Analysis Uncovers the Presence of Four Novel Viruses and Multiple Known Virus Genera in a Single Hibiscus rosa-sinensis Plant in Colombia. Viruses 2024; 16:267. [PMID: 38400042 PMCID: PMC10891833 DOI: 10.3390/v16020267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 01/31/2024] [Accepted: 02/01/2024] [Indexed: 02/25/2024] Open
Abstract
Hibiscus is not native to Colombia but well suited to its arid soil and dry climates. A single hibiscus plant from Risaralda, showing black spots on upper and lower sides of its leaves, was collected for virome analysis using meta-transcriptomic high-throughput sequencing technology. Bioinformatic analysis identified 12.5% of the total reads in the Ribo-Zero cDNA library which mapped to viral genomes. BLAST searches revealed the presence of carlavirus, potexvirus, and of known members of the genera Betacarmovirus, Cilevirus, Nepovirus, and Tobamovirus in the sample; confirmed by RT-PCR with virus-specific primers followed by amplicon sequencing. Furthermore, in silico analysis suggested the possibility of a novel soymovirus, and a new hibiscus strain of citrus leprosis virus C2 in the mixed infection. Both RNA dependent RNA polymerase and coat protein gene sequences of the potex and carla viruses shared less than 72% nucleotide and 80% amino acid identities with any alphaflexi- and betaflexi-virus sequences available in GenBank, identifying three novel carlavirus and one potexvirus species in the Hibiscus rosa-sinensis plant. The detection of physalis vein necrosis nepovirus and passion fruit green spot cilevirus in hibiscus are also new reports from Colombia. Overall, the meta-transcriptome analysis identified the complex virome associated with the black spot symptoms on hibiscus leaves and demonstrated the diversity of virus genera tolerated in the mixed infection of a single H. rosa-sinensis plant.
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Affiliation(s)
- Avijit Roy
- Molecular Plant Pathology Laboratory, Beltsville Agricultural Research Center, Agricultural Research Service, United States Department of Agriculture (USDA), Beltsville, MD 20705, USA
| | - Sam Grinstead
- Molecular Plant Pathology Laboratory, Beltsville Agricultural Research Center, Agricultural Research Service, United States Department of Agriculture (USDA), Beltsville, MD 20705, USA
| | - Guillermo Leon Martínez
- AGROSAVIA, Centro de Investigación La Libertad, Km.17 vía Pto. Lopez, Villavicencio, Meta, Colombia
| | | | - Schyler O Nunziata
- Plant Pathogen Confirmatory Diagnostics Laboratory, Science and Technology, Plant Protection and Quarantine, Animal and Plant Health Inspection Service, USDA, Laurel, MD 20708, USA
| | - Chellappan Padmanabhan
- Plant Pathogen Confirmatory Diagnostics Laboratory, Science and Technology, Plant Protection and Quarantine, Animal and Plant Health Inspection Service, USDA, Laurel, MD 20708, USA
| | - John Hammond
- Floral and Nursery Plants Research Unit, Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD 20705, USA
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Yan D, Han K, Lu Y, Peng J, Rao S, Wu G, Liu Y, Chen J, Zheng H, Yan F. The nanovirus U2 protein suppresses RNA silencing via three conserved cysteine residues. MOLECULAR PLANT PATHOLOGY 2024; 25:e13394. [PMID: 37823358 PMCID: PMC10782648 DOI: 10.1111/mpp.13394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Revised: 09/19/2023] [Accepted: 09/19/2023] [Indexed: 10/13/2023]
Abstract
Nanoviruses have multipartite, circular, single-stranded DNA genomes and cause huge production losses in legumes and other crops. No viral suppressor of RNA silencing (VSR) has yet been reported from a member of the genus Nanovirus. Here, we demonstrate that the nanovirus U2 protein is a VSR. The U2 protein of milk vetch dwarf virus (MDV) suppressed the silencing of the green fluorescent protein (GFP) gene induced by single-stranded and double-stranded RNA, and the systemic spread of the GFP silencing signal. An electrophoretic mobility shift assay showed that the U2 protein was able to bind double-stranded 21-nucleotide small interfering RNA (siRNA). The cysteine residues at positions 43, 79 and 82 in the MDV U2 protein are critical to its nuclear localization, self-interaction and siRNA-binding ability, and were essential for its VSR activity. In addition, expression of the U2 protein via a potato virus X vector induced more severe necrosis symptoms in Nicotiana benthamiana leaves. The U2 proteins of other nanoviruses also acted as VSRs, and the three conserved cysteine residues were indispensable for their VSR activity.
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Affiliation(s)
- Dankan Yan
- College of Life SciencesFujian Agriculture and Forestry UniversityFuzhouChina
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro‐Products, Institute of Plant VirologyNingbo UniversityNingboChina
- Institute of Plant Protection and Agro‐Products SafetyAnhui Academy of Agricultural SciencesHefeiChina
| | - Kelei Han
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro‐Products, Institute of Plant VirologyNingbo UniversityNingboChina
- Institute of Plant Protection and Agro‐Products SafetyAnhui Academy of Agricultural SciencesHefeiChina
| | - Yuwen Lu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro‐Products, Institute of Plant VirologyNingbo UniversityNingboChina
| | - Jiejun Peng
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro‐Products, Institute of Plant VirologyNingbo UniversityNingboChina
| | - Shaofei Rao
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro‐Products, Institute of Plant VirologyNingbo UniversityNingboChina
| | - Guanwei Wu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro‐Products, Institute of Plant VirologyNingbo UniversityNingboChina
| | - Yong Liu
- Institute of Plant ProtectionHunan Academy of Agricultural SciencesChangshaChina
| | - Jianping Chen
- College of Life SciencesFujian Agriculture and Forestry UniversityFuzhouChina
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro‐Products, Institute of Plant VirologyNingbo UniversityNingboChina
| | - Hongying Zheng
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro‐Products, Institute of Plant VirologyNingbo UniversityNingboChina
| | - Fei Yan
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro‐Products, Institute of Plant VirologyNingbo UniversityNingboChina
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Li Y, Liu S, Guo K, Ding W, Wang R. Virome of Pseudostellaria heterophylla: Identification and characterization of three novel carlaviruses and one novel amalgavirus associated with viral diseases of Pseudostellaria heterophylla. Front Microbiol 2022; 13:955089. [PMID: 36246219 PMCID: PMC9559581 DOI: 10.3389/fmicb.2022.955089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 09/12/2022] [Indexed: 11/30/2022] Open
Abstract
Pseudostellaria heterophylla is a traditional Chinese herbal medicine, which has been cultivated for hundreds of years. Viral diseases of P. heterophylla occur widely and limit the yield and quality of this medicinal plant. In this study, five leaf samples of P. heterophylla with typical viral symptoms were collected from four main producing regions that are distributed in Fujian, Guizhou, and Anhui Provinces in China and analyzed by next-generation sequencing. Comprehensive bioinformatics analyses revealed that nine viruses in five genera Carlavirus, Potyvirus, Fabavirus, Cucumovirus, and Amalgavirus infected P. heterophylla. Among these viruses, three novel and two known carlaviruses, tentatively designated Pseudostellaria heterophylla carlavirus 1, 2, and 3 (PhCV1, PhCV2, and PhCV3), Jasmine virus C isolate Ph (Ph-JVC) and Stevia carlavirus 1 isolate Ph (Ph-StCV1), respectively, were first identified in P. heterophylla. PhCV1-3 share a similar genomic organization and clear sequence homology with members in the genus Carlavirus and could potentially be classified as new species of this genus. One novel amalgavirus, tentatively designated P. heterophylla amalgavirus 1 (PhAV1), was first identified in P. heterophylla. It had a typical genomic organization of the genus Amalgavirus. In PhAV1, the + 1 programmed ribosomal frameshifting, which is prevalent in most amalgaviruses, was identified and used in the expression of RNA-dependent RNA polymerase (RdRp). Combined with a phylogenetic analysis, PhAV1 could potentially be classified as new species of the genus Amalgavirus. In addition, multiple Broad bean wilt virus 2 (BBWV2) variants, Turnip mosaic virus (TuMV), and Cucumber mosaic virus (CMV), which have been reported in P. heterophylla, were also detected in this study. The distribution of PhCV1-3, Ph-JVC, Ph-StCV1, TuMV, BBWV2, and CMV in four production regions in Fujian, Guizhou, and Anhui Provinces was determined. This study increased our understanding of P. heterophylla virome and provided valuable information for the development of a molecular diagnostic technique and control of viral diseases in P. heterophylla.
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Zhang C, Chen D, Yang G, Yu X, Wu J. Rice Stripe Mosaic Virus-Encoded P4 Is a Weak Suppressor of Viral RNA Silencing and Is Required for Disease Symptom Development. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:412-422. [PMID: 31841359 DOI: 10.1094/mpmi-08-19-0239-ia] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Viral suppressors of RNA silencing (VSRs) are a cluster of viral proteins that have evolved to counteract eukaryotic antiviral RNA silencing pathways, thereby contributing to viral pathogenicity. In this study, we revealed that the matrix protein P4 encoded by rice stripe mosaic virus (RSMV), which is an emerging cytoplasmic rhabdovirus, is a weak RNA silencing suppressor. By conducting yeast two-hybrid, bimolecular fluorescence complementation, and subcellular colocalization assays, we proved that P4 interacts with the rice endogenous suppressor of gene silencing 3 (OsSGS3). We also determined that P4 overexpression has no effect on OsSGS3 transcription. However, P4 can promote the degradation of OsSGS3 via ubiquitination and autophagy. Additionally, a potato virus X-based expression system was used to confirm that P4 enhances the development of mosaic symptoms on Nicotiana benthamiana leaves by promoting hydrogen peroxide accumulation but not cell death. To verify whether P4 is a pathogenicity factor in host plants, we generated transgenic P4-overexpressing rice plants that exhibited disease-related developmental defects including decreased plant height and excessive tillering. Our data suggest that RSMV-encoded P4 serves as a weak VSR that inhibits antiviral RNA silencing by targeting OsSGS3.
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Affiliation(s)
- Chao Zhang
- Vector-borne Virus Research Center, State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Institute of Plant Virology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Dong Chen
- Vector-borne Virus Research Center, State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Institute of Plant Virology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Guoyi Yang
- Vector-borne Virus Research Center, State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Institute of Plant Virology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Xiyuan Yu
- Vector-borne Virus Research Center, State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Institute of Plant Virology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Jianguo Wu
- Vector-borne Virus Research Center, State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Institute of Plant Virology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
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Maree HJ, Blouin AG, Diaz-Lara A, Mostert I, Al Rwahnih M, Candresse T. Status of the current vitivirus taxonomy. Arch Virol 2019; 165:451-458. [PMID: 31845154 DOI: 10.1007/s00705-019-04500-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 11/12/2019] [Indexed: 11/25/2022]
Abstract
Since the establishment of the genus Vitivirus, several additional viruses have been sequenced and proposed to represent new species of this genus. Currently, the International Committee on Taxonomy of Viruses recognizes 15 vitivirus species. The report of new vitiviruses that fail to completely adhere to the species demarcation criteria, the incorporation of non-vitivirus grapevine viruses in the unofficial "naming system", and the existence of non-grapevine vitiviruses lead to inconsistencies in classification. In this report, we give a brief overview of vitiviruses and use currently available information to clarify the present status of the vitivirus taxonomy.
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Affiliation(s)
- H J Maree
- Department of Genetics, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
- Citrus Research International, P.O. Box 2201, Matieland, 7602, South Africa.
| | - A G Blouin
- Integrated and Urban Plant Pathology Laboratory, Gembloux Agro-Bio Tech, University of Liège, 5030, Gembloux, Belgium
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 92169, Auckland, 1142, New Zealand
| | - A Diaz-Lara
- Department of Plant Pathology, University of California-Davis, Davis, CA, 95616, USA
| | - I Mostert
- Department of Genetics, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - M Al Rwahnih
- Department of Plant Pathology, University of California-Davis, Davis, CA, 95616, USA
| | - T Candresse
- INRAE, Univ. Bordeaux, UMR BFP, 33882, Villenave d'Ornon Cedex, France
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Wang X, Luo C, Xu Y, Zhang C, Bao M, Dou J, Wang Q, Cheng Y. Expression of the p24 silencing suppressor of Grapevine leafroll-associated virus 2 from Potato virus X or Barley stripe mosaic virus vector elicits hypersensitive responses in Nicotiana benthamiana. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2019; 142:34-42. [PMID: 31255907 DOI: 10.1016/j.plaphy.2019.06.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 05/24/2019] [Accepted: 06/23/2019] [Indexed: 06/09/2023]
Abstract
The 24-kDa protein (p24) encoded by Grapevine leafroll-associated virus 2 (GLRaV-2) is an RNA-silencing suppressor (RSS), but its effect on active viral infection is unclear. Using a Potato virus X (PVX)-based expression system, we demonstrated that p24 elicits lethal systemic necrosis in Nicotiana benthamiana, sharing typical characteristics of the hypersensitive response (HR), and that NbRAR1 (a cytoplasmic Zn2+-binding protein) is involved in the PVX-p24-mediated systemic necrosis. Moreover, expression of p24 from Barley stripe mosaic virus (BSMV) vector triggered local necrosis in infiltrated patches of N. benthamiana, likely inhibiting viral systemic spread. By deletion analysis, we demonstrated that amino acids (aa) 1 to 180, which are located in the region (aa 1-188) previously shown to be necessary for p24's RSS activity, is sufficient for p24 to elicit systemic necrosis in the context of PVX infection. Using substitution mutants, we revealed that silencing-suppression-defective mutants R2A and W54A induce only a mild necrotic response; two mutants without self-interaction ability previously shown to lose or retain weak suppression function also displayed decreased pathogenicity: W149A without RSS activity elicited a mild necrotic response, whereas V162H/L169H/L170H which retains weak RSS activity was able to induce systemic necrosis, but with a 1- to 2-day delay. Taken together, p24 plays an important role in GLRaV-2 pathogenesis, triggering HR-like necrosis in N. benthamiana plants when expressed from PVX or BSMV vector; both the silencing suppression and self-interaction are crucial for p24's pathogenicity activity, and the region of p24 for determining systemic necrosis is mapped to aa 1-180.
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Affiliation(s)
- Xianyou Wang
- Department of Pomology, China Agricultural University, Beijing, 100193, China; Key Laboratory of Viticulture and Enology, Ministry of Agriculture, Beijing, 100083, China
| | - Chen Luo
- Department of Pomology, China Agricultural University, Beijing, 100193, China; Key Laboratory of Viticulture and Enology, Ministry of Agriculture, Beijing, 100083, China
| | - Yanfei Xu
- DeLaval Tianjin Company, Tianjin, 300308, China
| | - Chenwei Zhang
- Department of Pomology, China Agricultural University, Beijing, 100193, China; Key Laboratory of Viticulture and Enology, Ministry of Agriculture, Beijing, 100083, China
| | - Mian Bao
- Department of Pomology, China Agricultural University, Beijing, 100193, China; Key Laboratory of Viticulture and Enology, Ministry of Agriculture, Beijing, 100083, China
| | - Junjie Dou
- Department of Pomology, China Agricultural University, Beijing, 100193, China; Key Laboratory of Viticulture and Enology, Ministry of Agriculture, Beijing, 100083, China
| | - Qi Wang
- Department of Plant Pathology, China Agricultural University, Beijing, 100193, China
| | - Yuqin Cheng
- Department of Pomology, China Agricultural University, Beijing, 100193, China; Key Laboratory of Viticulture and Enology, Ministry of Agriculture, Beijing, 100083, China.
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Peng L, Grinstead S, Kinard G, Wu LP, Li R. Molecular characterization and detection of two carlaviruses infecting cactus. Arch Virol 2019; 164:1873-1876. [PMID: 31076911 DOI: 10.1007/s00705-019-04279-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 04/10/2019] [Indexed: 11/27/2022]
Abstract
Two large contigs with sequence similarities to different carlaviruses were identified by high-throughput sequencing in samples from a cactus plant. The complete genomes of the two viruses, tentatively named "cactus carlavirus 1" (CCV-1) and "cactus carlavirus 2" (CCV-2), were determined to be 8,441 and 8,396 nucleotides long, respectively, excluding the poly(A) tail. These viruses have the typical genomic organization of members of the genus Carlavirus. CCV-1 appears to be a cactus isolate of the carlavirus HSO-2016a, with 90.1% nucleotide sequence identity between the two virus genomes, whereas CCV-2 may be classified as a member of a new species. The sequences of CCV-2 and other carlaviruses are 48.9-60.0% identical at the whole-genome level.
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Affiliation(s)
- L Peng
- Key Laboratory of Poyang Lake Environment and Resource, School of Life Science, Nanchang University, Nanchang, 330031, China
| | - S Grinstead
- USDA-ARS, National Germplasm Resources Laboratory, Beltsville, MD, 20705, USA
| | - G Kinard
- USDA-ARS, National Germplasm Resources Laboratory, Beltsville, MD, 20705, USA
| | - L-P Wu
- Key Laboratory of Poyang Lake Environment and Resource, School of Life Science, Nanchang University, Nanchang, 330031, China.
- USDA-ARS, National Germplasm Resources Laboratory, Beltsville, MD, 20705, USA.
| | - R Li
- USDA-ARS, National Germplasm Resources Laboratory, Beltsville, MD, 20705, USA.
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Prasad A, Sharma N, Muthamilarasan M, Rana S, Prasad M. Recent advances in small RNA mediated plant-virus interactions. Crit Rev Biotechnol 2019; 39:587-601. [PMID: 30947560 DOI: 10.1080/07388551.2019.1597830] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Small RNAs (sRNA) are reported to play pivotal roles in the epigenetic and post-transcriptional regulation of gene expression during growth, development, and stress response in plants. Recently, the involvement of two different classes of sRNAs namely, miRNAs (microRNAs), and siRNAs (small interfering RNAs) in biotic stress response has been underlined. Notably, during virus infection, these sRNAs deploy antiviral defense by regulating the gene expression of the modulators of host defense pathways. As a counter defense, viruses have evolved strategic pathways involving the production of suppressors that interfere with the host silencing machinery. This molecular arms race between the sophisticated gene regulatory mechanism of host plants fine-tuned by sRNAs and the defense response exhibited by the virus has gained much attention among the researchers. So far, several reports have been published showing the mechanistic insights on sRNA-regulated defense mechanism in response to virus infection in several crop plants. In this context, our review enumerates the molecular mechanisms underlying host immunity against viruses mediated by sRNAs, the counter defense strategies employed by viruses to surpass this immunogenic response and the advances made in our understanding of plant-virus interactions. Altogether, the report would be insightful for the researchers working to decode the sRNA-mediated defense response in crop plants challenged with virus infection.
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Affiliation(s)
- Ashish Prasad
- a National Institute of Plant Genome Research , New Delhi , India
| | - Namisha Sharma
- a National Institute of Plant Genome Research , New Delhi , India
| | - Mehanathan Muthamilarasan
- a National Institute of Plant Genome Research , New Delhi , India.,b ICAR-National Research Centre on Plant Biotechnology , New Delhi , India
| | - Sumi Rana
- a National Institute of Plant Genome Research , New Delhi , India.,b ICAR-National Research Centre on Plant Biotechnology , New Delhi , India
| | - Manoj Prasad
- a National Institute of Plant Genome Research , New Delhi , India
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Li X, Hataya T. Construction and characterization of an infectious cDNA clone of potato virus S developed from selected populations that survived genetic bottlenecks. Virol J 2019; 16:18. [PMID: 30728059 PMCID: PMC6364481 DOI: 10.1186/s12985-019-1124-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Accepted: 01/23/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Infectious cDNA clones are a powerful tool for studies on RNA viruses using reverse genetics. Potato virus S (PVS) is a carlavirus with a worldwide distribution. Although the complete genome sequences of many PVS isolates have been reported, the construction of an infectious cDNA clone of PVS is yet to be reported. The aim of this study is the development and molecular characterization of an infectious cDNA clone of PVS. METHODS A full-length cDNA clone pPVS-H-FL-AB was constructed by connecting eight cDNA clones of PVS isolate H95. Capped RNA transcripts from pPVS-H-FL-AB and a modified clone pPVS-H-FL-H, containing the consensus genome sequence of PVS-H95, proved to be non-infectious. Therefore, a full-length cDNA clone pPVS-H-FL-β was reconstructed from PVS-H00, isolated from PVS-H95 populations by repeating a single local lesion isolation in Chenopodium quinoa three times; PVS-H00 appeared to be a selected variant that survived genetic bottlenecks. The sequence of cDNA clone pPVS-H-FL-β was determined as the genome sequence of PVS-H00 and compared with the consensus sequence of PVS-H95 genome. RESULTS All Nicotiana occidentalis plants inoculated with ≥0.2 μg capped RNA transcripts from pPVS-H-FL-β developed symptoms on upper leaves, as observed with PVS-H00 inoculation. Similar levels of viral genomic and subgenomic RNAs and coat protein were detected in systemically infected leaves. Sequence comparison of PVS-H95 and PVS-H00 revealed 370 nucleotide polymorphisms (4.4% of the entire genome sequence), causing 91 amino acid substitutions in six open reading frames (ORFs). The infectivity of chimeric RNAs derived from recombinants between the two cDNA clones revealed that the lack of infectivity of pPVS-H-FL-H transcripts was due to ORF1, which encodes replicase and harbors 80 amino acid substitutions compared with pPVS-H-FL-β. Approximately 71.3% amino acid substitutions in replicase were located within the variable region of unknown function between the putative methyltransferase and ovarian tumor-like protease domains. CONCLUSIONS This is the first report of the development of an infectious cDNA clone of PVS. Our analyses suggest that PVS population within a plant exists as quasispecies and the replicase sequence diversity of PVS obstruct the construction of a full-length infectious cDNA clone.
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Affiliation(s)
- Xin Li
- Laboratory of Pathogen-Plant Interactions, Graduate School of Agriculture, Hokkaido University, Sapporo, 060-8589 Japan
| | - Tatsuji Hataya
- Laboratory of Pathogen-Plant Interactions, Research Faculty of Agriculture, Hokkaido University, Sapporo, 060-8589 Japan
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Zhang T, Zhao X, Jiang L, Yang X, Chen Y, Song X, Lu Y, Peng J, Zheng H, Wu Y, MacFarlane S, Chen J, Yan F. p15 encoded by Garlic virus X is a pathogenicity factor and RNA silencing suppressor. J Gen Virol 2018; 99:1515-1521. [PMID: 30207520 DOI: 10.1099/jgv.0.001144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Garlic virus X (GarVX) encodes a 15 kDa cysteine-rich protein (CRP). To investigate the function(s) of p15, its subcellular localization, role as a symptom determinant and capacity to act as a viral suppressor of RNA silencing (VSR) were analysed. Results showed that GFP-tagged p15 was distributed in the cytoplasm, nucleus and nucleolus. Expression of p15 from PVX caused additional systemic foliar malformation and led to increased accumulation of PVX, showing that p15 is a virulence factor for reconstructed PVX-p15. Moreover, using a transient agro-infiltration patch assay and a Turnip crinkle virus (TCV) movement complementation assay, it was demonstrated that p15 possesses weak RNA silencing suppressor activity. Removal of an amino acid motif resembling a nuclear localization signal (NLS) prevented p15 from accumulating in the nucleus but did not abolish its silencing suppression activity. This study provides the first insights into the multiple functions of the GarVX p15 protein.
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Affiliation(s)
- Tianhao Zhang
- 1College of Plant Protection, Shenyang Agriculture University, Shenyang 110161, Liaoning, PR China
| | - Xing Zhao
- 1College of Plant Protection, Shenyang Agriculture University, Shenyang 110161, Liaoning, PR China
| | - Liangliang Jiang
- 2Institute of Plant Virology, Ningbo University, Ningbo 315211, PR China
- 3State Key laboratory Breeding Base for Sustainable Control of Pest and Disease, Key Laboratory of Biotechnology in Plant Protection, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, PR China
- 4College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Xue Yang
- 1College of Plant Protection, Shenyang Agriculture University, Shenyang 110161, Liaoning, PR China
| | - Ying Chen
- 1College of Plant Protection, Shenyang Agriculture University, Shenyang 110161, Liaoning, PR China
| | - Xijiao Song
- 5Public Lab, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, PR China
| | - Yuwen Lu
- 2Institute of Plant Virology, Ningbo University, Ningbo 315211, PR China
- 3State Key laboratory Breeding Base for Sustainable Control of Pest and Disease, Key Laboratory of Biotechnology in Plant Protection, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, PR China
| | - Jiejun Peng
- 2Institute of Plant Virology, Ningbo University, Ningbo 315211, PR China
- 3State Key laboratory Breeding Base for Sustainable Control of Pest and Disease, Key Laboratory of Biotechnology in Plant Protection, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, PR China
| | - Hongying Zheng
- 2Institute of Plant Virology, Ningbo University, Ningbo 315211, PR China
- 3State Key laboratory Breeding Base for Sustainable Control of Pest and Disease, Key Laboratory of Biotechnology in Plant Protection, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, PR China
| | - Yuanhua Wu
- 1College of Plant Protection, Shenyang Agriculture University, Shenyang 110161, Liaoning, PR China
| | - Stuart MacFarlane
- 6The James Hutton Institute, Cell and Molecular Sciences Group, Invergowrie, Dundee DD2 5DA, UK
| | - Jianping Chen
- 2Institute of Plant Virology, Ningbo University, Ningbo 315211, PR China
- 3State Key laboratory Breeding Base for Sustainable Control of Pest and Disease, Key Laboratory of Biotechnology in Plant Protection, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, PR China
| | - Fei Yan
- 2Institute of Plant Virology, Ningbo University, Ningbo 315211, PR China
- 3State Key laboratory Breeding Base for Sustainable Control of Pest and Disease, Key Laboratory of Biotechnology in Plant Protection, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, PR China
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Fujita N, Komatsu K, Ayukawa Y, Matsuo Y, Hashimoto M, Netsu O, Teraoka T, Yamaji Y, Namba S, Arie T. N-terminal region of cysteine-rich protein (CRP) in carlaviruses is involved in the determination of symptom types. MOLECULAR PLANT PATHOLOGY 2018; 19:180-190. [PMID: 27868376 PMCID: PMC6638135 DOI: 10.1111/mpp.12513] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 10/19/2016] [Accepted: 11/14/2016] [Indexed: 05/04/2023]
Abstract
Plant viruses in the genus Carlavirus include more than 65 members. Plants infected with carlaviruses exhibit various symptoms, including leaf malformation and plant stunting. Cysteine-rich protein (CRP) encoded by carlaviruses has been reported to be a pathogenicity determinant. Carlavirus CRPs contain two motifs in their central part: a nuclear localization signal (NLS) and a zinc finger motif (ZF). In addition to these two conserved motifs, carlavirus CRPs possess highly divergent, N-terminal, 34 amino acid residues with unknown function. In this study, to analyse the role of these distinct domains, we tested six carlavirus CRPs for their RNA silencing suppressor activity, ability to enhance the pathogenicity of a heterologous virus and effects on virus accumulation levels. Although all six tested carlavirus CRPs showed RNA silencing suppressor activity at similar levels, symptoms induced by the Potato virus X (PVX) heterogeneous system exhibited two different patterns: leaf malformation and whole-plant stunting. The expression of each carlavirus CRP enhanced PVX accumulation levels, which were not correlated with symptom patterns. PVX-expressing CRP with mutations in either NLS or ZF did not induce symptoms, suggesting that both motifs play critical roles in symptom expression. Further analysis using chimeric CRPs, in which the N-terminal region was replaced with the corresponding region of another CRP, suggested that the N-terminal region of carlavirus CRPs determined the exhibited symptom types. The up-regulation of a plant gene upp-L, which has been reported in a previous study, was also observed in this study; however, the expression level was not responsible for symptom types.
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Affiliation(s)
- Naoko Fujita
- Laboratory of Plant Pathology, Graduate School of AgricultureTokyo University of Agriculture and Technology (TUAT)183‐8509 FuchuJapan
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life SciencesThe University of Tokyo113‐8657 TokyoJapan
| | - Ken Komatsu
- Laboratory of Plant Pathology, Graduate School of AgricultureTokyo University of Agriculture and Technology (TUAT)183‐8509 FuchuJapan
| | - Yu Ayukawa
- Laboratory of Plant Pathology, Graduate School of AgricultureTokyo University of Agriculture and Technology (TUAT)183‐8509 FuchuJapan
- United Graduate School of Agricultural ScienceTokyo University of Agriculture and TechnologyFuchu183‐8509Japan
| | - Yuki Matsuo
- Laboratory of Plant Pathology, Graduate School of AgricultureTokyo University of Agriculture and Technology (TUAT)183‐8509 FuchuJapan
| | - Masayoshi Hashimoto
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life SciencesThe University of Tokyo113‐8657 TokyoJapan
| | - Osamu Netsu
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life SciencesThe University of Tokyo113‐8657 TokyoJapan
| | - Tohru Teraoka
- Laboratory of Plant Pathology, Graduate School of AgricultureTokyo University of Agriculture and Technology (TUAT)183‐8509 FuchuJapan
| | - Yasuyuki Yamaji
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life SciencesThe University of Tokyo113‐8657 TokyoJapan
| | - Shigetou Namba
- Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life SciencesThe University of Tokyo113‐8657 TokyoJapan
| | - Tsutomu Arie
- Laboratory of Plant Pathology, Graduate School of AgricultureTokyo University of Agriculture and Technology (TUAT)183‐8509 FuchuJapan
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12
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Mann KS, Dietzgen RG. Functional analysis of a weak viral RNA silencing suppressor using two GFP variants as silencing inducers. J Virol Methods 2017; 239:50-57. [PMID: 27836657 DOI: 10.1016/j.jviromet.2016.10.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 10/20/2016] [Accepted: 10/31/2016] [Indexed: 11/24/2022]
Abstract
RNA silencing in plants can be triggered by the introduction of an exogenous gene. Green fluorescent protein (GFP) has been widely used as a visual reporter to study RNA silencing and viral-mediated suppression of RNA silencing in the model plant Nicotiana benthamiana. In transgenic N. benthamiana plants expressing an endoplasmic reticulum targeted GFP variant (16c) known as mGFP5, RNA silencing can be induced by ectopic over-expression of mGFP5. However, other GFP variants can also be used to induce GFP silencing in these plants. We compared the efficiency to induce local and systemic silencing of two commonly used GFP variants: enhanced GFP (eGFP) and mGFP5. Using lettuce necrotic yellows virus (LNYV) P protein to suppress GFP silencing, we demonstrate that eGFP gene, which is 76% identical at the nucleotide level to the endogenously expressed mGFP5 in 16c plants, triggers silencing more slowly and concurrently prolongs detectable silencing suppressor activity of the weak LNYV P suppressor, compared to the homologous mGFP5 gene. The use of eGFP as RNA silencing inducer in wild type or 16c plants appears to be a useful tool in identifying and analysing weak viral RNA silencing suppressor proteins whose activity might otherwise have been masked when challenged by a stronger RNA silencing response. We also show that reducing the dosage of strong dsRNA silencing inducers in conjunction with their homologous GFP targets facilitates the discovery and analysis of "weaker" RNA silencing suppressor activities.
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Affiliation(s)
- Krin S Mann
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, QLD, 4072, Australia
| | - Ralf G Dietzgen
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, QLD, 4072, Australia.
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13
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Tugume AK, Mukasa SB, Valkonen JPT. Mixed Infections of Four Viruses, the Incidence and Phylogenetic Relationships of Sweet Potato Chlorotic Fleck Virus (Betaflexiviridae) Isolates in Wild Species and Sweetpotatoes in Uganda and Evidence of Distinct Isolates in East Africa. PLoS One 2016; 11:e0167769. [PMID: 28005969 PMCID: PMC5179071 DOI: 10.1371/journal.pone.0167769] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 11/18/2016] [Indexed: 01/05/2023] Open
Abstract
Viruses infecting wild flora may have a significant negative impact on nearby crops, and vice-versa. Only limited information is available on wild species able to host economically important viruses that infect sweetpotatoes (Ipomoea batatas). In this study, Sweet potato chlorotic fleck virus (SPCFV; Carlavirus, Betaflexiviridae) and Sweet potato chlorotic stunt virus (SPCSV; Crinivirus, Closteroviridae) were surveyed in wild plants of family Convolvulaceae (genera Astripomoea, Ipomoea, Hewittia and Lepistemon) in Uganda. Plants belonging to 26 wild species, including annuals, biannuals and perennials from four agro-ecological zones, were observed for virus-like symptoms in 2004 and 2007 and sampled for virus testing. SPCFV was detected in 84 (2.9%) of 2864 plants tested from 17 species. SPCSV was detected in 66 (5.4%) of the 1224 plants from 12 species sampled in 2007. Some SPCSV-infected plants were also infected with Sweet potato feathery mottle virus (SPFMV; Potyvirus, Potyviridae; 1.3%), Sweet potato mild mottle virus (SPMMV; Ipomovirus, Potyviridae; 0.5%) or both (0.4%), but none of these three viruses were detected in SPCFV-infected plants. Co-infection of SPFMV with SPMMV was detected in 1.2% of plants sampled. Virus-like symptoms were observed in 367 wild plants (12.8%), of which 42 plants (11.4%) were negative for the viruses tested. Almost all (92.4%) the 419 sweetpotato plants sampled from fields close to the tested wild plants displayed virus-like symptoms, and 87.1% were infected with one or more of the four viruses. Phylogenetic and evolutionary analyses of the 3'-proximal genomic region of SPCFV, including the silencing suppressor (NaBP)- and coat protein (CP)-coding regions implicated strong purifying selection on the CP and NaBP, and that the SPCFV strains from East Africa are distinguishable from those from other continents. However, the strains from wild species and sweetpotato were indistinguishable, suggesting reciprocal movement of SPCFV between wild and cultivated Convolvulaceae plants in the field.
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Affiliation(s)
- Arthur K. Tugume
- Department of Agricultural Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland
- Department of Plant Sciences, Microbiology and Biotechnology, School of Biosciences, College of Natural Sciences, Makerere University, Kampala, Uganda
| | - Settumba B. Mukasa
- Department of Agricultural Production, School of Agricultural Sciences, College of Agricultural and Environmental Sciences, Makerere University, Kampala, Uganda
| | - Jari P. T. Valkonen
- Department of Agricultural Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland
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14
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Complete Genome Sequences of the Carlavirus Sweet potato chlorotic fleck virus from East Timor and Australia. GENOME ANNOUNCEMENTS 2016; 4:4/3/e00414-16. [PMID: 27231359 PMCID: PMC4882940 DOI: 10.1128/genomea.00414-16] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We present here the first complete genome sequences of Sweet potato chlorotic fleck virus (SPCFV) from sweet potato in Australia and East Timor, and we compare these with four complete SPCFV genomes from South Korea and one from Uganda. The Australian, East Timorese, South Korean, and Ugandan genomes differed considerably from each other.
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15
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Deng XG, Zhu T, Zhang DW, Lin HH. The alternative respiratory pathway is involved in brassinosteroid-induced environmental stress tolerance in Nicotiana benthamiana. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:6219-32. [PMID: 26175355 PMCID: PMC4588879 DOI: 10.1093/jxb/erv328] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Brassinosteroids (BRs), plant steroid hormones, play essential roles in modulating cell elongation, vascular differentiation, senescence, and stress responses. However, the mechanisms by which BRs regulate plant mitochondria and resistance to abiotic stress remain largely unclear. Mitochondrial alternative oxidase (AOX) is involved in the plant response to a variety of environmental stresses. In this report, the role of AOX in BR-induced tolerance against cold, polyethylene glycol (PEG), and high-light stresses was investigated. Exogenous applied brassinolide (BL, the most active BR) induced, while brassinazole (BRZ, a BR biosynthesis inhibitor) reduced alternative respiration and AOX1 expression in Nicotiana benthamiana. Chemical scavenging of H2O2 and virus-induced gene silencing (VIGS) of NbRBOHB compromised the BR-induced alternative respiratory pathway, and this result was further confirmed by NbAOX1 promoter analysis. Furthermore, inhibition of AOX activity by chemical treatment or a VIGS-based approach decreased plant resistance to environmental stresses and compromised BR-induced stress tolerance. Taken together, our results indicate that BR-induced AOX capability might contribute to the avoidance of superfluous reactive oxygen species accumulation and the protection of photosystems under stress conditions in N. benthamiana.
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Affiliation(s)
- Xing-Guang Deng
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610064, PR China Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, PR China
| | - Tong Zhu
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610064, PR China
| | - Da-Wei Zhang
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610064, PR China
| | - Hong-Hui Lin
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610064, PR China
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