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Sanfaçon H, Alam SB, Ghoshal B, Ghoshal K, Hui E, Jackson AO, Kakani K, Morris TJ, Nagy PD, Simon AE, Sit TL, Smith TJ, White KA, Xiang Y. D'Ann Rochon (1955-2022), a life of passion for plant virology. Virology 2023; 587:109874. [PMID: 37690385 DOI: 10.1016/j.virol.2023.109874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 08/28/2023] [Indexed: 09/12/2023]
Abstract
D'Ann Rochon passed away on November 29th 2022. She is remembered for her outstanding contributions to the field of plant virology, her strong commitment to high quality science and her dedication to the training and mentorship of the next generation of scientists. She was a research scientist for Agriculture and Agri-Food Canada and an Adjunct Professor for the University of British Columbia. Her research program provided new insights on the infection cycle of tombusviruses and related viruses, including ground-breaking research on the structure of virus particles, the mechanisms of virus transmission by fungal zoospores, and the complexity of plant-virus interactions. She also developed diagnostic antibodies for plum pox virus and little cherry virus 2 that have had a significant impact on the management of these viruses.
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Affiliation(s)
- Hélène Sanfaçon
- Summerland Research and Development Centre, Agriculture and Agri-Food Canada, 4200 Highway 97, V0H 1Z0, Summerland, BC, Canada.
| | - Syed Benazir Alam
- Nanotechnology Research Center, National Research Council Canada, 11421 Saskatchewan Dr NW, T6G 2M9, Edmonton, AB, Canada.
| | - Basudev Ghoshal
- Summerland Research and Development Centre, Agriculture and Agri-Food Canada, 4200 Highway 97, V0H 1Z0, Summerland, BC, Canada.
| | - Kankana Ghoshal
- Canadian Food Inspection Agency, Sidney Laboratory, Center for Plant Health, 8801 East Saanich Road, V8L 1H3, Victoria, BC, Canada.
| | - Elizabeth Hui
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
| | | | - Kishore Kakani
- Enzyme/Protein Engineering, Twist Bioscience, 681 Gateway Blvd., South San Francisco, CA 94080, USA.
| | - T Jack Morris
- School of Biological Sciences, University of Nebraska, Lincoln, USA.
| | - Peter D Nagy
- Department of Plant Pathology, University of Kentucky, Lexington, USA.
| | - Anne E Simon
- Department of Cell Biology and Molecular Genetics, University of Maryland - College Park, College Park, MD, USA.
| | - Tim L Sit
- Department of Entomology and Plant Pathology, NC State University, Campus Box 7616, Raleigh, NC 27695-7616, USA.
| | - Thomas J Smith
- University of Texas Medical Branch at Galveston, Department of Biochemistry and Molecular Biology, 301 University Boulevard, Route 0645, Galveston, TX, 77555, USA.
| | - K Andrew White
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada.
| | - Yu Xiang
- Summerland Research and Development Centre, Agriculture and Agri-Food Canada, 4200 Highway 97, V0H 1Z0, Summerland, BC, Canada.
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Xu M, Risse J, Kormelink R. Cap-snatching as a possible contributor to photosynthesis shut-off. J Gen Virol 2022; 103. [PMID: 35947091 DOI: 10.1099/jgv.0.001763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cap-snatching is a mechanism applied by segmented, negative strand (-) RNA viruses (NSVs) to initiate genome transcription. So far, the cap donor source of cytoplasmic-replicating NSVs has remained elusive. Recently, studies pointed to processing body (P body, PB) as the potential source for providing capped RNAs but conclusive evidence is still lacking. To attempt identifying these sources, here the 5' non-viral leader sequences of Tomato spotted wilt virus (TSWV) N mRNAs were analysed by high-throughput sequencing (HTS) from plants subjected to normal and heat-stress conditions, and subsequently mapped on host donor transcripts. The majority of non-viral heterogenous, host-derived leader sequences ranged in size between ~10-20 nt and contained A or AG residues at the cleavage site and the presence of certain sequence motifs. Mapping the capped-leader sequences to the 5' UTR region of genes encoded by the Nicotiana tabacum genome, identified 348 donor genes and which were specifically enriched in cellular photosynthesis pathway. Nineteen of those were clearly expressed differentially at normal condition versus heat-stress conditions. Although the results did not point towards snatching of capped-RNA leader sequences from certain cytoplasmic RNA granules in particular, they indicated photosynthesis downregulation (and development of disease symptoms) partially result from cap-snatching.
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Affiliation(s)
- Min Xu
- Laboratory of Virology, Department of Plant Sciences, Wageningen University and Research, Droevendaalsesteeg 1, 6708PB Wageningen, The Netherlands
| | - Judith Risse
- Laboratory of Bioinformatics, Department of Plant Sciences, Wageningen University and Research, Droevendaalsesteeg 1, 6708PB Wageningen, The Netherlands
| | - Richard Kormelink
- Laboratory of Virology, Department of Plant Sciences, Wageningen University and Research, Droevendaalsesteeg 1, 6708PB Wageningen, The Netherlands
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Zhai Y, Yuan Q, Qiu S, Li S, Li M, Zheng H, Wu G, Lu Y, Peng J, Rao S, Chen J, Yan F. Turnip mosaic virus impairs perinuclear chloroplast clustering to facilitate viral infection. PLANT, CELL & ENVIRONMENT 2021; 44:3681-3699. [PMID: 34331318 DOI: 10.1111/pce.14157] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 07/20/2021] [Accepted: 07/20/2021] [Indexed: 05/22/2023]
Abstract
Chloroplasts play crucial roles in plant defence against viral infection. We now report that chloroplast NADH dehydrogenase-like (NDH) complex M subunit gene (NdhM) was first up-regulated and then down-regulated in turnip mosaic virus (TuMV)-infected N. benthamiana. NbNdhM-silenced plants were more susceptible to TuMV, whereas overexpression of NbNdhM inhibited TuMV accumulation. Overexpression of NbNdhM significantly induced the clustering of chloroplasts around the nuclei and disturbing this clustering facilitated TuMV infection, suggesting that the clustering mediated by NbNdhM is a defence against TuMV. It was then shown that NbNdhM interacted with TuMV VPg, and that the NdhMs of different plant species interacted with the proteins of different viruses, implying that NdhM may be a common target of viruses. In the presence of TuMV VPg, NbNdhM, which is normally localized in the nucleus, chloroplasts, cell periphery and chloroplast stromules, colocalized with VPg at the nucleus and nucleolus, with significantly increased nuclear accumulation, while NbNdhM-mediated chloroplast clustering was significantly impaired. This study therefore indicates that NbNdhM has a defensive role in TuMV infection probably by inducing the perinuclear clustering of chloroplasts, and that the localization of NbNdhM is altered by its interaction with TuMV VPg in a way that promotes virus infection.
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Affiliation(s)
- Yushan Zhai
- College of Plant Protection, Northwest A & F University, Yangling, China
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
- Key Laboratory of Biotechnology in Plant Protection of MOA and Zhejiang Province, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Quan Yuan
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Shiyou Qiu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Saisai Li
- College of Biological & Environmental Sciences, Zhejiang Wanli University, Ningbo, China
| | - Miaomiao Li
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Hongying Zheng
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Guanwei Wu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Yuwen Lu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Jiejun Peng
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Shaofei Rao
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Jianping Chen
- College of Plant Protection, Northwest A & F University, Yangling, China
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
- Key Laboratory of Biotechnology in Plant Protection of MOA and Zhejiang Province, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Fei Yan
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
- Key Laboratory of Biotechnology in Plant Protection of MOA and Zhejiang Province, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
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Navarro JA, Saiz-Bonilla M, Sanchez-Navarro JA, Pallas V. The mitochondrial and chloroplast dual targeting of a multifunctional plant viral protein modulates chloroplast-to-nucleus communication, RNA silencing suppressor activity, encapsidation, pathogenesis and tissue tropism. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 108:197-218. [PMID: 34309112 DOI: 10.1111/tpj.15435] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 07/19/2021] [Indexed: 05/22/2023]
Abstract
Plant defense against melon necrotic spot virus (MNSV) is triggered by the viral auxiliary replicase p29 that is targeted to mitochondrial membranes causing morphological alterations, oxidative burst and necrosis. Here we show that MNSV coat protein (CP) was also targeted to mitochondria and mitochondrial-derived replication complexes [viral replication factories or complex (VRC)], in close association with p29, in addition to chloroplasts. CP import resulted in the cleavage of the R/arm domain previously implicated in genome binding during encapsidation and RNA silencing suppression (RSS). We also show that CP organelle import inhibition enhanced RSS activity, CP accumulation and VRC biogenesis but resulted in inhibition of systemic spreading, indicating that MNSV whole-plant infection requires CP organelle import. We hypothesize that to alleviate the p29 impact on host physiology, MNSV could moderate its replication and p29 accumulation by regulating CP RSS activity through organelle targeting and, consequently, eluding early-triggered antiviral response. Cellular and molecular events also suggested that S/P domains, which correspond to processed CP in chloroplast stroma or mitochondrion matrix, could mitigate host response inhibiting p29-induced necrosis. S/P deletion mainly resulted in a precarious balance between defense and counter-defense responses, generating either cytopathic alterations and MNSV cell-to-cell movement restriction or some degree of local movement. In addition, local necrosis and defense responses were dampened when RSS activity but not S/P organelle targeting was affected. Based on a robust biochemical and cellular analysis, we established that the mitochondrial and chloroplast dual targeting of MNSV CP profoundly impacts the viral infection cycle.
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Affiliation(s)
- Jose A Navarro
- Department of Molecular and Evolutionary Plant Virology, Institute for Plant Molecular and Cell Biology, Consejo Superior de Investigaciones Científicas-Universitat Politècnica de València, Av. Ingeniero Fausto Elio, Valencia, 46022, Spain
| | - Maria Saiz-Bonilla
- Department of Molecular and Evolutionary Plant Virology, Institute for Plant Molecular and Cell Biology, Consejo Superior de Investigaciones Científicas-Universitat Politècnica de València, Av. Ingeniero Fausto Elio, Valencia, 46022, Spain
| | - Jesus A Sanchez-Navarro
- Department of Molecular and Evolutionary Plant Virology, Institute for Plant Molecular and Cell Biology, Consejo Superior de Investigaciones Científicas-Universitat Politècnica de València, Av. Ingeniero Fausto Elio, Valencia, 46022, Spain
| | - Vicente Pallas
- Department of Molecular and Evolutionary Plant Virology, Institute for Plant Molecular and Cell Biology, Consejo Superior de Investigaciones Científicas-Universitat Politècnica de València, Av. Ingeniero Fausto Elio, Valencia, 46022, Spain
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5
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Changes in Subcellular Localization of Host Proteins Induced by Plant Viruses. Viruses 2021; 13:v13040677. [PMID: 33920930 PMCID: PMC8071230 DOI: 10.3390/v13040677] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/08/2021] [Accepted: 04/12/2021] [Indexed: 12/24/2022] Open
Abstract
Viruses are dependent on host factors at all parts of the infection cycle, such as translation, genome replication, encapsidation, and cell-to-cell and systemic movement. RNA viruses replicate their genome in compartments associated with the endoplasmic reticulum, chloroplasts, and mitochondria or peroxisome membranes. In contrast, DNA viruses replicate in the nucleus. Viral infection causes changes in plant gene expression and in the subcellular localization of some host proteins. These changes may support or inhibit virus accumulation and spread. Here, we review host proteins that change their subcellular localization in the presence of a plant virus. The most frequent change is the movement of host cytoplasmic proteins into the sites of virus replication through interactions with viral proteins, and the protein contributes to essential viral processes. In contrast, only a small number of studies document changes in the subcellular localization of proteins with antiviral activity. Understanding the changes in the subcellular localization of host proteins during plant virus infection provides novel insights into the mechanisms of plant–virus interactions and may help the identification of targets for designing genetic resistance to plant viruses.
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Alam SB, Reade R, Maghodia AB, Ghoshal B, Theilmann J, Rochon D. Targeting of cucumber necrosis virus coat protein to the chloroplast stroma attenuates host defense response. Virology 2021; 554:106-119. [PMID: 33418272 DOI: 10.1016/j.virol.2020.10.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/27/2020] [Accepted: 10/27/2020] [Indexed: 01/17/2023]
Abstract
Cucumber necrosis virus (CNV) is a (+)ssRNA virus that elicits spreading local and systemic necrosis in Nicotiana benthamiana. We previously showed that the CNV coat protein (CP) arm functions as a chloroplast transit peptide that targets a CP fragment containing the S and P domains to chloroplasts during infection. Here we show that several CP arm mutants that inefficiently target chloroplasts, along with a mutant that lacks the S and P domains, show an early onset of more localized necrosis along with protracted induction of pathogenesis related protein (PR1a). Agroinfiltrated CNV CP is shown to interfere with CNV p33 and Tomato bushy stunt virus p19 induced necrosis. Additionally, we provide evidence that a CP mutant that does not detectably enter the chloroplast stroma induces relatively higher levels of several plant defense-related genes compared to WT CNV. Together, our data suggest that targeting of CNV CP to the chloroplast stroma interferes with chloroplast-mediated plant defense.
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Affiliation(s)
- Syed Benazir Alam
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, V6T 1B4, Canada; Summerland Research and Development Centre, Agriculture and Agri-Food Canada, Summerland, BC, V0H 1Z0, Canada.
| | - Ron Reade
- Summerland Research and Development Centre, Agriculture and Agri-Food Canada, Summerland, BC, V0H 1Z0, Canada
| | - Ajay B Maghodia
- Summerland Research and Development Centre, Agriculture and Agri-Food Canada, Summerland, BC, V0H 1Z0, Canada
| | - Basudev Ghoshal
- Summerland Research and Development Centre, Agriculture and Agri-Food Canada, Summerland, BC, V0H 1Z0, Canada
| | - Jane Theilmann
- Summerland Research and Development Centre, Agriculture and Agri-Food Canada, Summerland, BC, V0H 1Z0, Canada
| | - D'Ann Rochon
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, V6T 1B4, Canada; Summerland Research and Development Centre, Agriculture and Agri-Food Canada, Summerland, BC, V0H 1Z0, Canada
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7
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Gao F, Zhao S, Men S, Kang Z, Hong J, Wei C, Hong W, Li Y. A non-structural protein encoded by Rice Dwarf Virus targets to the nucleus and chloroplast and inhibits local RNA silencing. SCIENCE CHINA. LIFE SCIENCES 2020; 63:1703-1713. [PMID: 32303960 DOI: 10.1007/s11427-019-1648-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 02/13/2020] [Indexed: 02/08/2023]
Abstract
RNA silencing is a potent antiviral mechanism in plants and animals. As a counter-defense, many viruses studied to date encode one or more viral suppressors of RNA silencing (VSR). In the latter case, how different VSRs encoded by a virus function in silencing remains to be fully understood. We previously showed that the nonstructural protein Pns10 of a Phytoreovirus, Rice dwarf virus (RDV), functions as a VSR. Here we present evidence that another nonstructural protein, Pns11, also functions as a VSR. While Pns10 was localized in the cytoplasm, Pns11 was localized both in the nucleus and chloroplasts. Pns11 has two bipartite nuclear localization signals (NLSs), which were required for nuclear as well as chloroplastic localization. The NLSs were also required for the silencing activities of Pns11. This is the first report that multiple VSRs encoded by a virus are localized in different subcellular compartments, and that a viral protein can be targeted to both the nucleus and chloroplast. These findings may have broad significance in studying the subcellular targeting of VSRs and other viral proteins in viral-host interactions.
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Affiliation(s)
- Feng Gao
- The State Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, 100871, China
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, 20742, USA
| | - Shanshan Zhao
- The State Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, 100871, China
- College of Plant Protection, Fujian Agriculture & Forestry University, Fuzhou, 350002, China
| | - Shuzhen Men
- College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Zhensheng Kang
- Department of Plant Protection, Northwestern Agriculture and Forestry University, Yangling, 712100, China
| | - Jian Hong
- College of Agriculture, Zhejiang University, Hangzhou, 310029, China
| | - Chunhong Wei
- The State Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, 100871, China
| | - Wei Hong
- The State Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, 100871, China.
- The First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, 310006, China.
| | - Yi Li
- The State Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, 100871, China.
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Yang X, Lu Y, Wang F, Chen Y, Tian Y, Jiang L, Peng J, Zheng H, Lin L, Yan C, Taliansky M, MacFarlane S, Wu Y, Chen J, Yan F. Involvement of the chloroplast gene ferredoxin 1 in multiple responses of Nicotiana benthamiana to Potato virus X infection. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:2142-2156. [PMID: 31872217 PMCID: PMC7094082 DOI: 10.1093/jxb/erz565] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 12/20/2019] [Indexed: 05/14/2023]
Abstract
The chloroplast protein ferredoxin 1 (FD1), with roles in the chloroplast electron transport chain, is known to interact with the coat proteins (CPs) of Tomato mosaic virus and Cucumber mosaic virus. However, our understanding of the roles of FD1 in virus infection remains limited. Here, we report that the Potato virus X (PVX) p25 protein interacts with FD1, whose mRNA and protein levels are reduced by PVX infection or by transient expression of p25. Silencing of FD1 by Tobacco rattle virus-based virus-induced gene silencing (VIGS) promoted the local and systemic infection of plants by PVX. Use of a drop-and-see (DANS) assay and callose staining revealed that the permeability of plasmodesmata (PDs) was increased in FD1-silenced plants together with a consistently reduced level of PD callose deposition. After FD1 silencing, quantitative reverse transcription-real-time PCR (qRT-PCR) analysis and LC-MS revealed these plants to have a low accumulation of the phytohormones abscisic acid (ABA) and salicylic acid (SA), which contributed to the decreased callose deposition at PDs. Overexpression of FD1 in transgenic plants manifested resistance to PVX infection, but the contents of ABA and SA, and the PD callose deposition were not increased in transgenic plants. Overexpression of FD1 interfered with the RNA silencing suppressor function of p25. These results demonstrate that interfering with FD1 function causes abnormal plant hormone-mediated antiviral processes and thus enhances PVX infection.
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Affiliation(s)
- Xue Yang
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
- Key Laboratory of Biotechnology in Plant Protection of MOA and Zhejiang Province, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
- Department of Plant Protection, Shenyang Agriculture University, Shenyang, China
| | - Yuwen Lu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Fang Wang
- Ningbo Academy of Agricultural Sciences, Ningbo, China
| | - Ying Chen
- Department of Plant Protection, Shenyang Agriculture University, Shenyang, China
| | - Yanzhen Tian
- College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Liangliang Jiang
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
- Key Laboratory of Biotechnology in Plant Protection of MOA and Zhejiang Province, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Jiejun Peng
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Hongying Zheng
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Lin Lin
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Chengqi Yan
- Ningbo Academy of Agricultural Sciences, Ningbo, China
| | - Michael Taliansky
- The James Hutton Institute, Cell and Molecular Sciences Group, Invergowrie, Dundee, UK
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the RAS, Moscow, Russia
| | - Stuart MacFarlane
- The James Hutton Institute, Cell and Molecular Sciences Group, Invergowrie, Dundee, UK
| | - Yuanhua Wu
- Department of Plant Protection, Shenyang Agriculture University, Shenyang, China
| | - Jianping Chen
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
- Key Laboratory of Biotechnology in Plant Protection of MOA and Zhejiang Province, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
- Department of Plant Protection, Shenyang Agriculture University, Shenyang, China
| | - Fei Yan
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
- Key Laboratory of Biotechnology in Plant Protection of MOA and Zhejiang Province, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
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Huang YP, Huang YW, Hsiao YJ, Li SC, Hsu YH, Tsai CH. Autophagy is involved in assisting the replication of Bamboo mosaic virus in Nicotiana benthamiana. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:4657-4670. [PMID: 31552430 PMCID: PMC6760330 DOI: 10.1093/jxb/erz244] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Indexed: 05/20/2023]
Abstract
Autophagy plays a critical role in plants under biotic stress, including the response to pathogen infection. We investigated whether autophagy-related genes (ATGs) are involved in infection with Bamboo mosaic virus (BaMV), a single-stranded positive-sense RNA virus. Initially, we observed that BaMV infection in Nicotiana benthamiana leaves upregulated the expression of ATGs but did not trigger cell death. The induction of ATGs, which possibly triggers autophagy, increased rather than diminished BaMV accumulation in the leaves, as revealed by gene knockdown and transient expression experiments. Furthermore, the inhibitor 3-methyladenine blocked autophagosome formation and the autophagy inducer rapamycin, which negatively and positively affected BaMV accumulation, respectively. Pull-down experiments with an antibody against orange fluorescent protein (OFP)-NbATG8f, an autophagosome marker protein, showed that both plus- and minus-sense BaMV RNAs could associate with NbATG8f. Confocal microscopy revealed that ATG8f-enriched vesicles possibly derived from chloroplasts contained both the BaMV viral RNA and its replicase. Thus, BaMV infection may induce the expression of ATGs possibly via autophagy to selectively engulf a portion of viral RNA-containing chloroplast. Virus-induced vesicles enriched with ATG8f could provide an alternative site for viral RNA replication or a shelter from the host silencing mechanism.
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Affiliation(s)
- Ying-Ping Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Ying-Wen Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Yung-Jen Hsiao
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Siou-Cen Li
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Yau-Huei Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
- Advanced Plant Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
| | - Ching-Hsiu Tsai
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
- Advanced Plant Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
- Research Center for Sustainable Energy and Nanotechnology, National Chung Hsing University, Taichung, Taiwan
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10
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Kotta-Loizou I, Peyret H, Saunders K, Coutts RHA, Lomonossoff GP. Investigating the Biological Relevance of In Vitro-Identified Putative Packaging Signals at the 5' Terminus of Satellite Tobacco Necrosis Virus 1 Genomic RNA. J Virol 2019; 93:e02106-18. [PMID: 30814279 PMCID: PMC6475782 DOI: 10.1128/jvi.02106-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 02/06/2019] [Indexed: 12/14/2022] Open
Abstract
Satellite tobacco necrosis virus 1 (STNV-1) is a model system for in vitro RNA encapsidation studies (N. Patel, E. C. Dykeman, R. H. A. Coutts, G. P. Lomonossoff, et al., Proc Natl Acad Sci U S A 112:2227-2232, 2015, https://doi.org/10.1073/pnas.1420812112; N. Patel, E. Wroblewski, G. Leonov, S. E. V. Phillips, et al., Proc Natl Acad Sci U S A 114:12255-12260, 2017, https://doi.org/10.1073/pnas.1706951114), leading to the identification of degenerate packaging signals (PSs) proposed to be involved in the recognition of its genome by the capsid protein (CP). The aim of the present work was to investigate whether these putative PSs can confer selective packaging of STNV-1 RNA in vivo and to assess the prospects of using decoy RNAs in antiviral therapy. We have developed an in planta packaging assay based on the transient expression of STNV-1 CP and have assessed the ability of the resulting virus-like particles (VLPs) to encapsidate mutant STNV-1 RNAs expected to have different encapsidation potential based on in vitro studies. The results revealed that >90% of the encapsidated RNAs are host derived, although there is some selectivity of packaging for STNV-1 RNA and certain host RNAs. Comparison of the packaging efficiencies of mutant STNV-1 RNAs showed that they are encapsidated mainly according to their abundance within the cells, rather than the presence or absence of the putative PSs previously identified from in vitro studies. In contrast, subsequent infection experiments demonstrated that host RNAs represent only <1% of virion content. Although selective encapsidation of certain host RNAs was noted, no direct correlation could be made between this preference and the presence of potential PSs in the host RNA sequences. Overall, the data illustrate that the differences in RNA packaging efficiency identified through in vitro studies are insufficient to explain the specific packaging of STNV-1 RNA.IMPORTANCE Viruses preferentially encapsidate their own genomic RNA, sometimes as a result of the presence of clearly defined packaging signals (PSs) in their genome sequence. Recently, a novel form of short degenerate PSs has been proposed (N. Patel, E. C. Dykeman, R. H. A. Coutts, G. P. Lomonossoff, et al., Proc Natl Acad Sci U S A 112:2227-2232, 2015, https://doi.org/10.1073/pnas.1420812112; N. Patel, E. Wroblewski, G. Leonov, S. E. V. Phillips, et al., Proc Natl Acad Sci U S A 114:12255-12260, 2017, https://doi.org/10.1073/pnas.1706951114) using satellite tobacco necrosis virus 1 (STNV-1) as a model system for in vitro studies. It has been suggested that competing with these putative PSs may constitute a novel therapeutic approach against pathogenic single-stranded RNA viruses. Our work demonstrates that the previously identified PSs have no discernible significance for the selective packaging of STNV-1 in vivo in the presence and absence of competition or replication: viral sequences are encapsidated mostly on the basis of their abundance within the cell, while encapsidation of host RNAs also occurs. Nevertheless, the putative PSs identified in STNV-1 RNA may still have applications in bionanotechnology, such as the in vitro selective packaging of RNA molecules.
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Affiliation(s)
- Ioly Kotta-Loizou
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Hadrien Peyret
- Department of Biological Chemistry, John Innes Centre, Norwich, United Kingdom
| | - Keith Saunders
- Department of Biological Chemistry, John Innes Centre, Norwich, United Kingdom
| | - Robert H A Coutts
- Department of Biological and Environmental Sciences, University of Hertfordshire, Hatfield, United Kingdom
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Vaira AM, Lim HS, Bauchan G, Gulbronson CJ, Miozzi L, Vinals N, Natilla A, Hammond J. The interaction of Lolium latent virus major coat protein with ankyrin repeat protein NbANKr redirects it to chloroplasts and modulates virus infection. J Gen Virol 2018; 99:730-742. [PMID: 29557771 DOI: 10.1099/jgv.0.001043] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Lolium latent virus (LoLV) major coat protein sequence contains a typical chloroplast transit peptide (cTP) domain. In infected Nicotiana benthamiana leaf tissue, LoLV coat proteins can be detected at the chloroplast. In transient expression, several N-terminal deletions of the CP sequence, increasing in length, result in disruption of the domain functionality, markedly affecting intracellular localization. A yeast two-hybrid-based study using LoLV CP as bait identified several potentially interacting Arabidopsis host proteins, most of them with chloroplast-linked pathways. One of them, an ankyrin repeat protein, was studied in detail. The N. benthamiana homologue (NbANKr) targets chloroplasts, is able to co-localize with LoLV CP at chloroplast membranes in transient expression and shows a robust interaction with LoLV CP in vivo by BiFC, which has been confirmed by yeast two-hybrid data. Silencing NbANKr genes in N. benthamiana plants, prior to challenging with LoLV by mechanical inoculation, affects LoLV infection, significantly reducing the level of viral RNA in young leaves, compared to levels in control plants, and suggesting an inhibition of virus movement. Silencing of NbANKr has no obvious effect on plant phenotype, but is able to interfere with LoLV infection, opening the way for a new strategy for virus infection control.
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Affiliation(s)
- A M Vaira
- Institute for Sustainable Plant Protection, IPSP-CNR, Strada delle Cacce 73, 10135, Torino, Italy
- USDA-ARS, USNA, Floral and Nursery Plant Research Unit, 10300 Baltimore Ave, Beltsville, MD, USA
| | - H S Lim
- USDA-ARS, USNA, Floral and Nursery Plant Research Unit, 10300 Baltimore Ave, Beltsville, MD, USA
- Department of Applied Biology, Chungnam National University, Daejeon, 305-764, Republic of Korea
| | - G Bauchan
- USDA-ARS, BARC, Electron and Confocal Microscopy Unit, 10300 Baltimore Ave, Beltsville, MD, USA
| | - C J Gulbronson
- USDA-ARS, USNA, Floral and Nursery Plant Research Unit, 10300 Baltimore Ave, Beltsville, MD, USA
- Oak Ridge Institute for Science and Education (ORISE) Postdoctoral Fellow, USA
| | - L Miozzi
- Institute for Sustainable Plant Protection, IPSP-CNR, Strada delle Cacce 73, 10135, Torino, Italy
| | - N Vinals
- Institute for Sustainable Plant Protection, IPSP-CNR, Strada delle Cacce 73, 10135, Torino, Italy
| | - A Natilla
- USDA-ARS, BARC, Molecular Plant Pathology Laboratory, 10300 Baltimore Ave, Beltsville, MD, USA
- Present address: Arc Horizon, LLC, Innovation Park, 1736 West Paul Dirac Dr., Tallahassee, FL, USA
| | - J Hammond
- USDA-ARS, USNA, Floral and Nursery Plant Research Unit, 10300 Baltimore Ave, Beltsville, MD, USA
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The role of chloroplasts in plant pathology. Essays Biochem 2018; 62:21-39. [PMID: 29273582 DOI: 10.1042/ebc20170020] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 11/22/2017] [Accepted: 11/28/2017] [Indexed: 12/13/2022]
Abstract
Plants have evolved complex tolerance systems to survive abiotic and biotic stresses. Central to these programmes is a sophisticated conversation of signals between the chloroplast and the nucleus. In this review, we examine the antagonism between abiotic stress tolerance (AST) and immunity: we propose that to generate immunogenic signals, plants must disable AST systems, in particular those that manage reactive oxygen species (ROS), while the pathogen seeks to reactivate or enhance those systems to achieve virulence. By boosting host systems of AST, pathogens trick the plant into suppressing chloroplast immunogenic signals and steer the host into making an inappropriate immune response. Pathogens disrupt chloroplast function, both transcriptionally-by secreting effectors that alter host gene expression by interacting with defence-related kinase cascades, with transcription factors, or with promoters themselves-and post-transcriptionally, by delivering effectors that enter the chloroplast or alter the localization of host proteins to change chloroplast activities. These mechanisms reconfigure the chloroplast proteome and chloroplast-originating immunogenic signals in order to promote infection.
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Bhattacharyya D, Chakraborty S. Chloroplast: the Trojan horse in plant-virus interaction. MOLECULAR PLANT PATHOLOGY 2018; 19:504-518. [PMID: 28056496 PMCID: PMC6638057 DOI: 10.1111/mpp.12533] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 12/22/2016] [Accepted: 01/03/2017] [Indexed: 05/14/2023]
Abstract
The chloroplast is one of the most dynamic organelles of a plant cell. It carries out photosynthesis, synthesizes major phytohormones, plays an active part in the defence response and is crucial for interorganelle signalling. Viruses, on the other hand, are extremely strategic in manipulating the internal environment of the host cell. The chloroplast, a prime target for viruses, undergoes enormous structural and functional damage during viral infection. Indeed, large proportions of affected gene products in a virus-infected plant are closely associated with the chloroplast and the process of photosynthesis. Although the chloroplast is deficient in gene silencing machinery, it elicits the effector-triggered immune response against viral pathogens. Virus infection induces the organelle to produce an extensive network of stromules which are involved in both viral propagation and antiviral defence. From studies over the last few decades, the involvement of the chloroplast in the regulation of plant-virus interaction has become increasingly evident. This review presents an exhaustive account of these facts, with their implications for pathogenicity. We have attempted to highlight the intricacies of chloroplast-virus interactions and to explain the existing gaps in our current knowledge, which will enable virologists to utilize chloroplast genome-based antiviral resistance in economically important crops.
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Affiliation(s)
- Dhriti Bhattacharyya
- Molecular Virology Laboratory, School of Life SciencesJawaharlal Nehru UniversityNew Delhi110 067India
| | - Supriya Chakraborty
- Molecular Virology Laboratory, School of Life SciencesJawaharlal Nehru UniversityNew Delhi110 067India
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Evidence that Hsc70 Is Associated with Cucumber Necrosis Virus Particles and Plays a Role in Particle Disassembly. J Virol 2017; 91:JVI.01555-16. [PMID: 27807229 DOI: 10.1128/jvi.01555-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 10/25/2016] [Indexed: 11/20/2022] Open
Abstract
Uncoating of a virus particle to expose its nucleic acid is a critical aspect of the viral multiplication cycle, as it is essential for the establishment of infection. In the present study, we investigated the role of plant HSP70 homologs in the uncoating process of Cucumber necrosis virus (CNV), a nonenveloped positive-sense single-stranded RNA [(+)ssRNA] virus having a T=3 icosahedral capsid. We have found through Western blot analysis and mass spectrometry that the HSP70 homolog Hsc70-2 copurifies with CNV particles. Virus overlay and immunogold labeling assays suggest that Hsc70-2 is physically bound to virions. Furthermore, trypsin digestion profiles suggest that the bound Hsc70-2 is partially protected by the virus, indicating an intimate association with particles. In investigating a possible role of Hsc70-2 in particle disassembly, we showed that particles incubated with Hsp70/Hsc70 antibody produce fewer local lesions than those incubated with prebleed control antibody on Chenopodium quinoa In conjunction, CNV virions purified using CsCl and having undetectable amounts of Hsc70-2 produce fewer local lesions. We also have found that plants with elevated levels of HSP70/Hsc70 produce higher numbers of local lesions following CNV inoculation. Finally, incubation of recombinant Nicotiana benthamiana Hsc70-2 with virus particles in vitro leads to conformational changes or partial disassembly of capsids as determined by transmission electron microscopy, and particles are more sensitive to chymotrypsin digestion. This is the first report suggesting that a cellular Hsc70 chaperone is involved in disassembly of a plant virus. IMPORTANCE Virus particles must disassemble and release their nucleic acid in order to establish infection in a cell. Despite the importance of disassembly in the ability of a virus to infect its host, little is known about this process, especially in the case of nonenveloped spherical RNA viruses. Previous work has shown that host HSP70 homologs play multiple roles in the CNV infection cycle. We therefore examined the potential role of these cellular components in the CNV disassembly process. We show that the HSP70 family member Hsc70-2 is physically associated with CNV virions and that HSP70 antibody reduces the ability of CNV to establish infection. Statistically significantly fewer lesions are produced when virions having undetectable HSc70-2 are used as an inoculum. Finally incubation of Hsc70-2 with CNV particles results in conformational changes in particles. Taken together, our data point to an important role of the host factor Hsc70-2 in CNV disassembly.
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Zhao J, Zhang X, Hong Y, Liu Y. Chloroplast in Plant-Virus Interaction. Front Microbiol 2016; 7:1565. [PMID: 27757106 PMCID: PMC5047884 DOI: 10.3389/fmicb.2016.01565] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 09/20/2016] [Indexed: 11/16/2022] Open
Abstract
In plants, the chloroplast is the organelle that conducts photosynthesis. It has been known that chloroplast is involved in virus infection of plants for approximate 70 years. Recently, the subject of chloroplast-virus interplay is getting more and more attention. In this article we discuss the different aspects of chloroplast-virus interaction into three sections: the effect of virus infection on the structure and function of chloroplast, the role of chloroplast in virus infection cycle, and the function of chloroplast in host defense against viruses. In particular, we focus on the characterization of chloroplast protein-viral protein interactions that underlie the interplay between chloroplast and virus. It can be summarized that chloroplast is a common target of plant viruses for viral pathogenesis or propagation; and conversely, chloroplast and its components also can play active roles in plant defense against viruses. Chloroplast photosynthesis-related genes/proteins (CPRGs/CPRPs) are suggested to play a central role during the complex chloroplast-virus interaction.
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Affiliation(s)
- Jinping Zhao
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua UniversityBeijing, China
- State Key Laboratory Breeding Base for Sustainable Control of Pest and Disease, Key Laboratory of Biotechnology in Plant Protection, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural SciencesHangzhou, China
| | - Xian Zhang
- Research Centre for Plant RNA Signaling, School of Life and Environmental Sciences, Hangzhou Normal UniversityHangzhou, China
| | - Yiguo Hong
- Research Centre for Plant RNA Signaling, School of Life and Environmental Sciences, Hangzhou Normal UniversityHangzhou, China
| | - Yule Liu
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua UniversityBeijing, China
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Kumari R, Kumar S, Singh L, Hallan V. Movement Protein of Cucumber Mosaic Virus Associates with Apoplastic Ascorbate Oxidase. PLoS One 2016; 11:e0163320. [PMID: 27668429 PMCID: PMC5036820 DOI: 10.1371/journal.pone.0163320] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Accepted: 09/07/2016] [Indexed: 01/13/2023] Open
Abstract
Plant viral movement proteins facilitate virion movement mainly through interaction with a number of factors from the host. We report the association of a cell wall localized ascorbate oxidase (CsAO4) from Cucumis sativus with the movement protein (MP) of Cucumber mosaic virus (CMV). This was identified first in a yeast two-hybrid screen and validated by in vivo pull down and bimolecular fluorescence complementation (BiFC) assays. The BiFC assay showed localization of the bimolecular complexes of these proteins around the cell wall periphery as punctate spots. The expression of CsAO4 was induced during the initial infection period (up to 72 h) in CMV infected Nicotiana benthamiana plants. To functionally validate its role in viral spread, we analyzed the virus accumulation in CsAO4 overexpressing Arabidopsis thaliana and transiently silenced N. benthamiana plants (through a Tobacco rattle virus vector). Overexpression had no evident effect on virus accumulation in upper non-inoculated leaves of transgenic lines in comparison to WT plants at 7 days post inoculation (dpi). However, knockdown resulted in reduced CMV accumulation in systemic (non-inoculated) leaves of NbΔAO-pTRV2 silenced plants as compared to TRV inoculated control plants at 5 dpi (up to 1.3 fold difference). In addition, functional validation supported the importance of AO in plant development. These findings suggest that AO and viral MP interaction helps in early viral movement; however, it had no major effect on viral accumulation after 7 dpi. This study suggests that initial induction of expression of AO on virus infection and its association with viral MP helps both towards targeting of the MP to the apoplast and disrupting formation of functional AO dimers for spread of virus to nearby cells, reducing the redox defense of the plant during initial stages of infection.
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Affiliation(s)
- Reenu Kumari
- Plant Virology lab, CSIR-Institute of Himalayan Bioresource Technology, Palampur, 176061, Himachal Pradesh, India
- Department of Biotechnology, Guru Nanak Dev University, Amritsar, 143005, India
| | - Surender Kumar
- Plant Virology lab, CSIR-Institute of Himalayan Bioresource Technology, Palampur, 176061, Himachal Pradesh, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Institute of Himalayan Bioresource Technology (CSIR-IHBT) Campus, Palampur, India
| | - Lakhmir Singh
- Department of Biotechnology, DAV University, Sarmastpur, Jalandhar, 144012, Punjab, India
| | - Vipin Hallan
- Plant Virology lab, CSIR-Institute of Himalayan Bioresource Technology, Palampur, 176061, Himachal Pradesh, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Institute of Himalayan Bioresource Technology (CSIR-IHBT) Campus, Palampur, India
- * E-mail:
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17
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Li Y, Cui H, Cui X, Wang A. The altered photosynthetic machinery during compatible virus infection. Curr Opin Virol 2016; 17:19-24. [DOI: 10.1016/j.coviro.2015.11.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2015] [Revised: 10/22/2015] [Accepted: 11/09/2015] [Indexed: 01/09/2023]
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Abstract
In plants, the chloroplast is the organelle that conducts photosynthesis. It has been known that chloroplast is involved in virus infection of plants for approximate 70 years. Recently, the subject of chloroplast-virus interplay is getting more and more attention. In this article we discuss the different aspects of chloroplast-virus interaction into three sections: the effect of virus infection on the structure and function of chloroplast, the role of chloroplast in virus infection cycle, and the function of chloroplast in host defense against viruses. In particular, we focus on the characterization of chloroplast protein-viral protein interactions that underlie the interplay between chloroplast and virus. It can be summarized that chloroplast is a common target of plant viruses for viral pathogenesis or propagation; and conversely, chloroplast and its components also can play active roles in plant defense against viruses. Chloroplast photosynthesis-related genes/proteins (CPRGs/CPRPs) are suggested to play a central role during the complex chloroplast-virus interaction.
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Affiliation(s)
- Jinping Zhao
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua UniversityBeijing, China; State Key Laboratory Breeding Base for Sustainable Control of Pest and Disease, Key Laboratory of Biotechnology in Plant Protection, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural SciencesHangzhou, China
| | - Xian Zhang
- Research Centre for Plant RNA Signaling, School of Life and Environmental Sciences, Hangzhou Normal University Hangzhou, China
| | - Yiguo Hong
- Research Centre for Plant RNA Signaling, School of Life and Environmental Sciences, Hangzhou Normal University Hangzhou, China
| | - Yule Liu
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University Beijing, China
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Alam SB, Rochon D. Cucumber Necrosis Virus Recruits Cellular Heat Shock Protein 70 Homologs at Several Stages of Infection. J Virol 2015; 90:3302-17. [PMID: 26719261 PMCID: PMC4794660 DOI: 10.1128/jvi.02833-15] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 12/16/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED RNA viruses often depend on host factors for multiplication inside cells due to the constraints of their small genome size and limited coding capacity. One such factor that has been exploited by several plant and animal viruses is heat shock protein 70 (HSP70) family homologs which have been shown to play roles for different viruses in viral RNA replication, viral assembly, disassembly, and cell-to-cell movement. Using next generation sequence analysis, we reveal that several isoforms of Hsp70 and Hsc70 transcripts are induced to very high levels during cucumber necrosis virus (CNV) infection of Nicotiana benthamiana and that HSP70 proteins are also induced by at least 10-fold. We show that HSP70 family protein homologs are co-opted by CNV at several stages of infection. We have found that overexpression of Hsp70 or Hsc70 leads to enhanced CNV genomic RNA, coat protein (CP), and virion accumulation, whereas downregulation leads to a corresponding decrease. Hsc70-2 was found to increase solubility of CNV CP in vitro and to increase accumulation of CNV CP independently of viral RNA replication during coagroinfiltration in N. benthamiana. In addition, virus particle assembly into virus-like particles in CP agroinfiltrated plants was increased in the presence of Hsc70-2. HSP70 was found to increase the targeting of CNV CP to chloroplasts during infection, reinforcing the role of HSP70 in chloroplast targeting of host proteins. Hence, our findings have led to the discovery of a highly induced host factor that has been co-opted to play multiple roles during several stages of the CNV infection cycle. IMPORTANCE Because of the small size of its RNA genome, CNV is dependent on interaction with host cellular components to successfully complete its multiplication cycle. We have found that CNV induces HSP70 family homologs to a high level during infection, possibly as a result of the host response to the high levels of CNV proteins that accumulate during infection. Moreover, we have found that CNV co-opts HSP70 family homologs to facilitate several aspects of the infection process such as viral RNA, coat protein and virus accumulation. Chloroplast targeting of the CNV CP is also facilitated, which may aid in CNV suppression of host defense responses. Several viruses have been shown to induce HSP70 during infection and others to utilize HSP70 for specific aspects of infection such as replication, assembly, and disassembly. We speculate that HSP70 may play multiple roles in the infection processes of many viruses.
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Affiliation(s)
- Syed Benazir Alam
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
| | - D'Ann Rochon
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada Summerland Research and Development Centre, Agriculture and Agri-Food Canada, Summerland, British Columbia, Canada
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Bhattacharyya D, Gnanasekaran P, Kumar RK, Kushwaha NK, Sharma VK, Yusuf MA, Chakraborty S. A geminivirus betasatellite damages the structural and functional integrity of chloroplasts leading to symptom formation and inhibition of photosynthesis. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:5881-95. [PMID: 26113193 PMCID: PMC4566980 DOI: 10.1093/jxb/erv299] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Geminivirus infection often causes severe vein clearing symptoms in hosts. Recently a betasatellite has emerged as a key regulator of symptom induction. To understand the host-betasatellite interactions in the process of symptom development, a systematic study was carried out involving symptoms induced by a betasatellite associated with radish leaf curl disease (RaLCB) in Nicotiana benthamiana. It has been found that βC1 protein localized to chloroplasts of host cells, and RaLCB lacking βC1, which failed to produce symptoms, had no effect on chloroplast ultrastructure. Vein flecking induced by transiently expressed βC1 was associated with chloroplast ultrastructure. In addition, the betasatellite down-regulates expression of genes involved in chlorophyll biosynthesis as well as genes involved in chloroplast development and plastid translocation. Interestingly, the expression of key host genes involved in chlorophyll degradation remains unaffected. Betasatellite infection drastically reduced the numbers of active reaction centres and the plastoquinol pool size in leaves exhibiting vein clearing symptoms. Betasatellite-mediated impediments at different stages of chloroplast functionality affect the photosynthetic efficiency of N. benthamiana. To the best of the authors' knowledge, this is the first evidence of a chloroplast-targeting protein encoded by a DNA virus which induces vein clearing and structurally and functionally damages chloroplasts in plants.
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Affiliation(s)
- Dhriti Bhattacharyya
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi-110 067, India
| | - Prabu Gnanasekaran
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi-110 067, India
| | - Reddy Kishore Kumar
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi-110 067, India
| | - Nirbhay Kumar Kushwaha
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi-110 067, India
| | - Veerendra Kumar Sharma
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi-110 067, India
| | - Mohd Aslam Yusuf
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi-110 067, India
| | - Supriya Chakraborty
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi-110 067, India
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Encapsidation of Host RNAs by Cucumber Necrosis Virus Coat Protein during both Agroinfiltration and Infection. J Virol 2015; 89:10748-61. [PMID: 26269190 DOI: 10.1128/jvi.01466-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 08/03/2015] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED Next-generation sequence analysis of virus-like particles (VLPs) produced during agroinfiltration of cucumber necrosis virus (CNV) coat protein (CP) and of authentic CNV virions was conducted to assess if host RNAs can be encapsidated by CNV CP. VLPs containing host RNAs were found to be produced during agroinfiltration, accumulating to approximately 1/60 the level that CNV virions accumulated during infection. VLPs contained a variety of host RNA species, including the major rRNAs as well as cytoplasmic, chloroplast, and mitochondrial mRNAs. The most predominant host RNA species encapsidated in VLPs were chloroplast encoded, consistent with the efficient targeting of CNV CP to chloroplasts during agroinfiltration. Interestingly, droplet digital PCR analysis showed that the CNV CP mRNA expressed during agroinfiltration was the most efficiently encapsidated mRNA, suggesting that the CNV CP open reading frame may contain a high-affinity site or sites for CP binding and thus contribute to the specificity of CNV RNA encapsidation. Approximately 0.09% to 0.7% of the RNA derived from authentic CNV virions contained host RNA, with chloroplast RNA again being the most prominent species. This is consistent with our previous finding that a small proportion of CNV CP enters chloroplasts during the infection process and highlights the possibility that chloroplast targeting is a significant aspect of CNV infection. Remarkably, 6 to 8 of the top 10 most efficiently encapsidated nucleus-encoded RNAs in CNV virions correspond to retrotransposon or retrotransposon-like RNA sequences. Thus, CNV could potentially serve as a vehicle for horizontal transmission of retrotransposons to new hosts and thereby significantly influence genome evolution. IMPORTANCE Viruses predominantly encapsidate their own virus-related RNA species due to the possession of specific sequences and/or structures on viral RNA which serve as high-affinity binding sites for the coat protein. In this study, we show, using next-generation sequence analysis, that CNV also encapsidates host RNA species, which account for ∼0.1% of the RNA packaged in CNV particles. The encapsidated host RNAs predominantly include chloroplast RNAs, reinforcing previous observations that CNV CP enters chloroplasts during infection. Remarkably, the most abundantly encapsidated cytoplasmic mRNAs consisted of retrotransposon-like RNA sequences, similar to findings recently reported for flock house virus (A. Routh, T. Domitrovic, and J. E. Johnson, Proc Natl Acad Sci U S A 109:1907-1912, 2012). Encapsidation of retrotransposon sequences may contribute to their horizontal transmission should CNV virions carrying retrotransposons infect a new host. Such an event could lead to large-scale genomic changes in a naive plant host, thus facilitating host evolutionary novelty.
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Ghoshal K, Theilmann J, Reade R, Sanfacon H, Rochon D. The Cucumber leaf spot virus p25 auxiliary replicase protein binds and modifies the endoplasmic reticulum via N-terminal transmembrane domains. Virology 2014; 468-470:36-46. [PMID: 25129437 PMCID: PMC7112066 DOI: 10.1016/j.virol.2014.07.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 06/28/2014] [Accepted: 07/13/2014] [Indexed: 11/23/2022]
Abstract
Cucumber leaf spot virus (CLSV) is a member of the Aureusvirus genus, family Tombusviridae. The auxiliary replicase of Tombusvirids has been found to localize to endoplasmic reticulum (ER), peroxisomes or mitochondria; however, localization of the auxiliary replicase of aureusviruses has not been determined. We have found that the auxiliary replicase of CLSV (p25) fused to GFP colocalizes with ER and that three predicted transmembrane domains (TMDs) at the N-terminus of p25 are sufficient for targeting, although the second and third TMDs play the most prominent roles. Confocal analysis of CLSV infected 16C plants shows that the ER becomes modified including the formation of punctae at connections between ER tubules and in association with the nucleus. Ultrastructural analysis shows that the cytoplasm contains numerous vesicles which are also found between the perinuclear ER and nuclear membrane. It is proposed that these vesicles correspond to modified ER used as sites for CLSV replication.
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Affiliation(s)
- Kankana Ghoshal
- University of British Columbia, Faculty of Land and Food Systems, Vancouver, British Columbia, Canada V6T 1Z4
| | - Jane Theilmann
- Agriculture and Agri-Food Canada Pacific Agri-Food Research Centre, 4200 Hwy 97, Summerland, British Columbia, Canada V0H 1Z0
| | - Ron Reade
- Agriculture and Agri-Food Canada Pacific Agri-Food Research Centre, 4200 Hwy 97, Summerland, British Columbia, Canada V0H 1Z0
| | - Helene Sanfacon
- Agriculture and Agri-Food Canada Pacific Agri-Food Research Centre, 4200 Hwy 97, Summerland, British Columbia, Canada V0H 1Z0
| | - D'Ann Rochon
- University of British Columbia, Faculty of Land and Food Systems, Vancouver, British Columbia, Canada V6T 1Z4; Agriculture and Agri-Food Canada Pacific Agri-Food Research Centre, 4200 Hwy 97, Summerland, British Columbia, Canada V0H 1Z0.
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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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Rochon D, Singh B, Reade R, Theilmann J, Ghoshal K, Alam SB, Maghodia A. The p33 auxiliary replicase protein of Cucumber necrosis virus targets peroxisomes and infection induces de novo peroxisome formation from the endoplasmic reticulum. Virology 2014; 452-453:133-42. [PMID: 24606690 DOI: 10.1016/j.virol.2013.12.035] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 12/23/2013] [Accepted: 12/24/2013] [Indexed: 11/17/2022]
Abstract
Tombusviruses replicate on pre-existing organelles such as peroxisomes or mitochondria, the membranes of which become extensively reorganized into multivesicular bodies (MVBs) during the infection process. Cucumber necrosis virus (CNV) has previously been shown to replicate in association with peroxisomes in yeast. We show that CNV induces MVBs from peroxisomes in infected plants and that GFP-tagged p33 auxiliary replicase protein colocalizes with YFP(SKL), a peroxisomal marker. Most remarkably, the ER of CNV infected Nicotiana benthamiana 16C plants undergoes a dramatic reorganization producing numerous new peroxisome-like structures that associate with CNV p33, thus likely serving as a new site for viral RNA replication. We also show that plants agroinfiltrated with p33 develop CNV-like necrotic symptoms which are associated with increased levels of peroxide. Since peroxisomes are a site for peroxide catabolism, and peroxide is known to induce plant defense responses, we suggest that dysfunctional peroxisomes contribute to CNV induced necrosis.
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Affiliation(s)
- D'Ann Rochon
- Agriculture and Agri-Food Canada Pacific Agri-Food Research Centre, 4200 Hwy 97, Summerland, BC, Canada V0H 1Z0; University of British Columbia Faculty of Land and Food Systems Vancouver, BC, Canada V6T 1Z4.
| | - Bhavana Singh
- University of British Columbia Faculty of Land and Food Systems Vancouver, BC, Canada V6T 1Z4
| | - Ron Reade
- Agriculture and Agri-Food Canada Pacific Agri-Food Research Centre, 4200 Hwy 97, Summerland, BC, Canada V0H 1Z0
| | - Jane Theilmann
- Agriculture and Agri-Food Canada Pacific Agri-Food Research Centre, 4200 Hwy 97, Summerland, BC, Canada V0H 1Z0
| | - Kankana Ghoshal
- University of British Columbia Faculty of Land and Food Systems Vancouver, BC, Canada V6T 1Z4
| | - Syed Benazir Alam
- University of British Columbia Faculty of Land and Food Systems Vancouver, BC, Canada V6T 1Z4
| | - Ajay Maghodia
- Agriculture and Agri-Food Canada Pacific Agri-Food Research Centre, 4200 Hwy 97, Summerland, BC, Canada V0H 1Z0; University of British Columbia Faculty of Land and Food Systems Vancouver, BC, Canada V6T 1Z4
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25
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Non-encapsidation activities of the capsid proteins of positive-strand RNA viruses. Virology 2013; 446:123-32. [PMID: 24074574 PMCID: PMC3818703 DOI: 10.1016/j.virol.2013.07.023] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 07/11/2013] [Accepted: 07/20/2013] [Indexed: 02/08/2023]
Abstract
Viral capsid proteins (CPs) are characterized by their role in forming protective shells around viral genomes. However, CPs have additional and important roles in the virus infection cycles and in the cellular responses to infection. These activities involve CP binding to RNAs in both sequence-specific and nonspecific manners as well as association with other proteins. This review focuses on CPs of both plant and animal-infecting viruses with positive-strand RNA genomes. We summarize the structural features of CPs and describe their modulatory roles in viral translation, RNA-dependent RNA synthesis, and host defense responses. We review regulatory activities of the capsid proteins of (+)-strand RNA viruses. Activities of capsid proteins due to RNA binding and protein binding. Effects of capsid proteins on viral processes. Effects of capsid proteins on cellular processes. Regulatory activities of the capsid proteins are affected by capsid concentrations.
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26
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Martin SL, He L, Meilleur F, Guenther RH, Sit TL, Lommel SA, Heller WT. New insight into the structure of RNA in red clover necrotic mosaic virus and the role of divalent cations revealed by small-angle neutron scattering. Arch Virol 2013; 158:1661-9. [PMID: 23483344 DOI: 10.1007/s00705-013-1650-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 01/24/2013] [Indexed: 11/25/2022]
Abstract
Red clover necrotic mosaic virus (RCNMV) is a 36-nm-diameter, T = 3 icosahedral plant virus with a genome that is split between two single-stranded RNA molecules of approximately 3.9 kb and 1.5 kb, as well as a 400-nucleotide degradation product. The structure of the virus capsid and its response to removing Ca(2+) and Mg(2+) was previously studied by cryo-electron microscopy (cryo-EM) (Sherman et al. J Virol 80:10395-10406, 2006) but the structure of the RNA was only partially resolved in that study. To better understand the organization of the RNA and conformational changes resulting from the removal of divalent cations, small-angle neutron scattering with contrast variation experiments were performed. The results expand upon the cryo-EM results by clearly showing that virtually all of the RNA is contained in a thin shell that is in contact with the interior domains of the viral capsid protein, and they provide new insight into changes in the RNA packing that result from removal of divalent cations.
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Affiliation(s)
- Stanton L Martin
- Department of Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA
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Jang C, Seo EY, Nam J, Bae H, Gim YG, Kim HG, Cho IS, Lee ZW, Bauchan GR, Hammond J, Lim HS. Insights into Alternanthera mosaic virus TGB3 Functions: Interactions with Nicotiana benthamiana PsbO Correlate with Chloroplast Vesiculation and Veinal Necrosis Caused by TGB3 Over-Expression. FRONTIERS IN PLANT SCIENCE 2013; 4:5. [PMID: 23386854 PMCID: PMC3560364 DOI: 10.3389/fpls.2013.00005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Accepted: 01/08/2013] [Indexed: 05/18/2023]
Abstract
Alternanthera mosaic virus (AltMV) triple gene block 3 (TGB3) protein is involved in viral movement. AltMV TGB3 subcellular localization was previously shown to be distinct from that of Potato virus X (PVX) TGB3, and a chloroplast binding domain identified; veinal necrosis and chloroplast vesiculation were observed in Nicotiana benthamiana when AltMV TGB3 was over-expressed from PVX. Plants with over-expressed TGB3 showed more lethal damage under dark conditions than under light. Yeast-two-hybrid analysis and bimolecular fluorescence complementation (BiFC) reveal that Arabidopsis thaliana PsbO1 has strong interactions with TGB3; N. benthamiana PsbO (NbPsbO) also showed obvious interaction signals with TGB3 through BiFC. These results demonstrate an important role for TGB3 in virus cell-to-cell movement and virus-host plant interactions. The Photosystem II oxygen-evolving complex protein PsbO interaction with TGB3 is presumed to have a crucial role in symptom development and lethal damage under dark conditions. In order to further examine interactions between AtPsbO1, NbPsbO, and TGB3, and to identify the binding domain(s) in TGB3 protein, BiFC assays were performed between AtPsbO1 or NbPsbO and various mutants of TGB3. Interactions with C-terminally deleted TGB3 were significantly weaker than those with wild-type TGB3, and both N-terminally deleted TGB3 and a TGB3 mutant previously shown to lose chloroplast interactions failed to interact detectably with PsbO in BiFC. To gain additional information about TGB3 interactions in AltMV-susceptible plants, we cloned 12 natural AltMV TGB3 sequence variants into a PVX expression vector to examine differences in symptom development in N. benthamiana. Symptom differences were observed on PVX over-expression, with all AltMV TGB3 variants showing more severe symptoms than the WT PVX control, but without obvious correlation to sequence differences.
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Affiliation(s)
- Chanyong Jang
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
| | - Eun-Young Seo
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
| | - Jiryun Nam
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
| | - Hanhong Bae
- School of Biotechnology, Yeungnam UniversityGyeongsan, South Korea
| | - Yeong Guk Gim
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
| | - Hong Gi Kim
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
| | - In Sook Cho
- National Institute of Horticultural and Herbal Science, Rural Development AdministrationSuwon, South Korea
| | - Zee-Won Lee
- Division of Life Science, Korea Basic Science InstituteDaejeon, South Korea
| | - Gary R. Bauchan
- Electron and Confocal Microscopy Unit, Beltsville Agricultural Research Center, Agricultural Research Service, United States Department of AgricultureBeltsville, MD, USA
| | - John Hammond
- Floral and Nursery Plants Research Unit, US National Arboretum, Agricultural Research Service, United States Department of AgricultureBeltsville, MD, USA
- *Correspondence: John Hammond, Floral and Nursery Plants Research Unit, US National Arboretum, United States Department of Agriculture, Agricultural Research Service, 10300 Baltimore Avenue, B-010A, Beltsville, MD 20705, USA. e-mail: ; Hyoun-Sub Lim, Department of Applied Biology, Chungnam National University, 79 Daehangno, Yuseong-gu, Daejeon 305-764, South Korea. e-mail:
| | - Hyoun-Sub Lim
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
- *Correspondence: John Hammond, Floral and Nursery Plants Research Unit, US National Arboretum, United States Department of Agriculture, Agricultural Research Service, 10300 Baltimore Avenue, B-010A, Beltsville, MD 20705, USA. e-mail: ; Hyoun-Sub Lim, Department of Applied Biology, Chungnam National University, 79 Daehangno, Yuseong-gu, Daejeon 305-764, South Korea. e-mail:
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28
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Krenz B, Jeske H, Kleinow T. The induction of stromule formation by a plant DNA-virus in epidermal leaf tissues suggests a novel intra- and intercellular macromolecular trafficking route. FRONTIERS IN PLANT SCIENCE 2012; 3:291. [PMID: 23293643 PMCID: PMC3530832 DOI: 10.3389/fpls.2012.00291] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2012] [Accepted: 12/06/2012] [Indexed: 05/20/2023]
Abstract
Stromules are dynamic thin protrusions of membrane envelope from plant cell plastids. Despite considerable progress in understanding the importance of certain cytoskeleton elements and motor proteins for stromule maintenance, their function within the cell has yet to be unraveled. Several viruses cause a remodulation of plastid structures and stromule biogenesis within their host plants. For RNA-viruses these interactions were demonstrated to be relevant to the infection process. An involvement of plastids and stromules is assumed in the DNA-virus life cycle as well, but their functional role needs to be determined. Recent findings support a participation of heat shock cognate 70 kDa protein (cpHSC70-1)-containing stromules induced by a DNA-virus infection (Abutilon mosaic virus, AbMV, Geminiviridae) in intra- and intercellular molecule exchange. The chaperone cpHSC70-1 was shown to interact with the AbMV movement protein (MP). Bimolecular fluorescence complementation confirmed the interaction of cpHSC70-1 and MP, and showed a homo-oligomerization of either protein in planta. The complexes were detected at the cellular margin and co-localized with plastids. In healthy plant tissues cpHSC70-1-oligomers occurred in distinct spots at chloroplasts and in small filaments extending from plastids to the cell periphery. AbMV-infection induced a cpHSC70-1-containing stromule network that exhibits elliptical dilations and transverses whole cells. Silencing of the cpHSC70 gene revealed an impact of cpHSC70 on chloroplast stability and restricted AbMV movement, but not viral DNA accumulation. Based on these data, a model is suggested in which these stromules function in molecule exchange between plastids and other organelles and perhaps other cells. AbMV may utilize cpHSC70-1 for trafficking along plastids and stromules into a neighboring cell or from plastids into the nucleus. Experimental approaches to investigate this hypothesis are discussed.
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Affiliation(s)
- Björn Krenz
- Plant Pathology and Plant-Microbe Biology, Cornell UniversityIthaca, NY, USA
| | - Holger Jeske
- Molecular Biology and Plant Virology, Institute of Biology, Universität StuttgartStuttgart, Germany
| | - Tatjana Kleinow
- Molecular Biology and Plant Virology, Institute of Biology, Universität StuttgartStuttgart, Germany
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29
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Vaira AM, Lim HS, Bauchan GR, Owens RA, Natilla A, Dienelt MM, Reinsel MD, Hammond J. Lolium latent virus (Alphaflexiviridae) coat proteins: expression and functions in infected plant tissue. J Gen Virol 2012; 93:1814-1824. [PMID: 22573739 DOI: 10.1099/vir.0.042960-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
The genome of Lolium latent virus (LoLV; genus Lolavirus, family Alphaflexiviridae) is encapsidated by two carboxy-coterminal coat protein (CP) variants (about 28 and 33 kDa), in equimolar proportions. The CP ORF contains two 5'-proximal AUGs encoding Met 1 and Met 49, respectively promoting translation of the 33 and 28 kDa CP variants. The 33 kDa CP N-terminal domain includes a 42 aa sequence encoding a putative chloroplast transit peptide, leading to protein cleavage and alternative derivation of the approximately 28 kDa CP. Mutational analysis of the two in-frame start codons and of the putative proteolytic-cleavage site showed that the N-terminal sequence is crucial for efficient cell-to-cell movement, functional systemic movement, homologous CP interactions and particle formation, but is not required for virus replication. Blocking production of the 28 kDa CP by internal initiation shows no major outcome, whereas additional mutation to prevent proteolytic cleavage at the chloroplast membrane has a dramatic effect on virus infection.
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Affiliation(s)
- Anna Maria Vaira
- USDA-ARS, USNA, Floral and Nursery Plants Research Unit, 10300 Baltimore Avenue, Beltsville, MD, USA
- Istituto di Virologia Vegetale CNR, Strada delle Cacce 73, 10135, Torino, Italy
| | - Hyoun-Sub Lim
- Department of Applied Biology, Chungnam National University, Daejeon, 305-764, Republic of Korea
| | - Gary R Bauchan
- USDA-ARS, PSI, Electron and Confocal Microscopy Unit, 10300 Baltimore Avenue, Beltsville, MD, USA
| | - Robert A Owens
- USDA-ARS, PSI, Molecular Plant Pathology Laboratory, 10300 Baltimore Avenue, Beltsville, MD, USA
| | - Angela Natilla
- USDA-ARS, PSI, Molecular Plant Pathology Laboratory, 10300 Baltimore Avenue, Beltsville, MD, USA
| | - Margaret M Dienelt
- USDA-ARS, USNA, Floral and Nursery Plants Research Unit, 10300 Baltimore Avenue, Beltsville, MD, USA
| | - Michael D Reinsel
- USDA-ARS, USNA, Floral and Nursery Plants Research Unit, 10300 Baltimore Avenue, Beltsville, MD, USA
| | - John Hammond
- USDA-ARS, USNA, Floral and Nursery Plants Research Unit, 10300 Baltimore Avenue, Beltsville, MD, USA
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Kriechbaumer V, von Löffelholz O, Abell BM. Chaperone receptors: guiding proteins to intracellular compartments. PROTOPLASMA 2012; 249:21-30. [PMID: 21461941 DOI: 10.1007/s00709-011-0270-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Accepted: 03/02/2011] [Indexed: 05/04/2023]
Abstract
Despite mitochondria and chloroplasts having their own genome, 99% of mitochondrial proteins (Rehling et al., Nat Rev Mol Cell Biol 5:519-530, 2004) and more than 95% of chloroplast proteins (Soll, Curr Opin Plant Biol 5:529-535, 2002) are encoded by nuclear DNA, synthesised in the cytosol and imported post-translationally. Protein targeting to these organelles depends on cytosolic targeting factors, which bind to the precursor, and then interact with membrane receptors to deliver the precursor into a translocase. The molecular chaperones Hsp70 and Hsp90 have been widely implicated in protein targeting to mitochondria and chloroplasts, and receptors capable of recognising these chaperones have been identified at the surface of both these organelles (Schlegel et al., Mol Biol Evol 24:2763-2774, 2007). The role of these chaperone receptors is not fully understood, but they have been shown to increase the efficiency of protein targeting (Young et al., Cell 112:41-50, 2003; Qbadou et al., EMBO J 25:1836-1847, 2006). Whether these receptors contribute to the specificity of targeting is less clear. A class of chaperone receptors bearing tetratricopeptide repeat domains is able to specifically bind the highly conserved C terminus of Hsp70 and/or Hsp90. Interestingly, at least of one these chaperone receptors can be found on each organelle (Schlegel et al., Mol Biol Evol 24:2763-2774, 2007), which suggests a universal role in protein targeting for these chaperone receptors. This review will investigate the role that chaperone receptors play in targeting efficiency and specificity, as well as examining recent in silico approaches to find novel chaperone receptors.
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Turnip yellow mosaic virus forms infectious particles without the native beta-annulus structure and flexible coat protein N-terminus. Virology 2012; 422:165-73. [DOI: 10.1016/j.virol.2011.10.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 09/20/2011] [Accepted: 10/19/2011] [Indexed: 11/22/2022]
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Manfre A, Glenn M, Nuñez A, Moreau RA, Dardick C. Light quantity and photosystem function mediate host susceptibility to Turnip mosaic virus via a salicylic acid-independent mechanism. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:315-27. [PMID: 21091158 DOI: 10.1094/mpmi-08-10-0191] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Evidence going as far back as the early part of the 20th century suggests that both light and chloroplast function may play key roles in host susceptibility to viruses. Despite the long history of such work, confirmation of these phenomena and a determination of the underlying mechanisms remain elusive. Here, we revisited these questions using modern imaging technologies to study the susceptibility of Nicotiana benthamiana to Turnip mosaic virus (TuMV). We found that both light deficiency and photosystem impairment increased the susceptibility of N. benthamiana to TuMV infection. Time-lapse photography studies indicated that, under these conditions, rub-inoculated plants exhibited greater numbers of infection foci and more rapid foci development. The rate of systemic movement was also accelerated though cell-to-cell movement appeared unchanged. Inhibition of salicylic acid (SA)-mediated defense responses is not likely responsible for changes in susceptibility because SA and pathogen response-1 gene induction were not affected by light deficiency or chloroplast impairment and treatment of plants with SA had no measureable impact on TuMV infection. Taken together, these data suggest that both light and optimal chloroplast function influence virus infection either by limiting the cellular resources needed by TuMV to establish replication complexes or the host's ability to activate SA-independent defenses.
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Affiliation(s)
- A Manfre
- United States Department of Agriculture, Appalachian Fruit Research Station, WV, USA
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33
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Hao X, Lu A, Sokal N, Bhagwat B, Leung E, Mao R, Reade R, Wu Y, Rochon D, Xiang Y. Cucumber necrosis virus p20 is a viral suppressor of RNA silencing. Virus Res 2011; 155:423-32. [DOI: 10.1016/j.virusres.2010.11.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 11/20/2010] [Accepted: 11/26/2010] [Indexed: 10/18/2022]
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Hui E, Xiang Y, Rochon D. Distinct regions at the N-terminus of the Cucumber necrosis virus coat protein target chloroplasts and mitochondria. Virus Res 2010; 153:8-19. [PMID: 20600385 DOI: 10.1016/j.virusres.2010.06.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2010] [Revised: 06/08/2010] [Accepted: 06/22/2010] [Indexed: 11/18/2022]
Abstract
Cucumber necrosis virus (CNV) is a spherical virus consisting of 180 identical coat protein (CP) subunits. The N-terminus of the CP subunit contains a 58aa RNA binding (R) domain and a 34aa arm that connects the R domain to the shell. These regions are known to play critical roles in virus assembly and disassembly. It has recently been shown that a region encompassing the arm can function as a chloroplast transit peptide (TP) in infected plants and that targeting may represent a means for virus particle disassembly. In this study, we further delineate the TP region and show that a 22aa sequence at the N-terminus of the shell enhances chloroplast targeting. We also demonstrate that R domain specifically co-localizes with mitochondria in agroinfiltrated plants. Deletion analyses show that the N-terminal 39 amino acids of the R domain are sufficient for mitochondrial targeting and that this region contains features typical of mitochondrial presequences. The R/arm region is found to be dually targeted to mitochondria and chloroplasts suggesting that this region of the CP plays a critical role in determining the fate of CP during the infection process.
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Affiliation(s)
- Elizabeth Hui
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
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35
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Reade R, Kakani K, Rochon D. A highly basic KGKKGK sequence in the RNA-binding domain of the Cucumber necrosis virus coat protein is associated with encapsidation of full-length CNV RNA during infection. Virology 2010; 403:181-8. [PMID: 20483445 DOI: 10.1016/j.virol.2010.03.045] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 03/03/2010] [Accepted: 03/27/2010] [Indexed: 11/21/2022]
Abstract
The Cucumber necrosis virus particle is a T=3 icosahedron consisting of 180 identical coat protein (CP) subunits. The N-terminal 58 aa residue segment of the CP R domain is believed to bind viral RNA within virions and during assembly. We report results of in vivo experiments that examine the role of the R domain in assembly. Deletion analyses identified 3 conserved 5-10 aa regions as playing critical roles. A highly basic KGKKGK sequence was found to be both necessary and sufficient for encapsidation of the full-length genome and polymorphic virions were produced in mutants lacking the KGKKGK sequence. The amount of full-length RNA present in virions was substantially reduced in R domain mutants where 2 of the 4 lysine residues were substituted with alanine, whereas substitution of 4 lysines by arginine had only a modest effect. The potential role of the R domain in formation of a scaffold for particle assembly is discussed.
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Affiliation(s)
- Ron Reade
- Pacific Agri-Food Research Centre, Summerland, British Columbia, Canada V0H 1Z0
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36
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Qiao Y, Li HF, Wong SM, Fan ZF. Plastocyanin transit peptide interacts with Potato virus X coat protein, while silencing of plastocyanin reduces coat protein accumulation in chloroplasts and symptom severity in host plants. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2009; 22:1523-34. [PMID: 19888818 DOI: 10.1094/mpmi-22-12-1523] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Potato virus X coat protein (PVXCP) is, through communication with host proteins, involved in processes such as virus movement and symptom development. Here, we report that PVXCP also interacts with the precursor of plastocyanin, a protein involved in photosynthesis, both in vitro and in vivo. Yeast two-hybrid analysis indicated that PVXCP interacted with only the plastocyanin transit peptide. In subsequent bimolecular fluorescence complementation assays, both proteins were collocated within chloroplasts. Western blot analyses of chloroplast fractions showed that PVXCP could be detected in the envelope, stroma, and lumen fractions. Transmission electron microscopy demonstrated that grana were dilated in PVX-infected Nicotiana benthamiana. Furthermore, virus-induced gene silencing of plastocyanin by prior infection of N. benthamiana using a Tobacco rattle virus vector reduced the severity of symptoms that developed following subsequent PVX infection as well as the accumulation of PVXCP in isolated chloroplasts. However, PVXCP could not be detected in pea chloroplasts in an in vitro re-uptake assay using the plastocyanin precursor protein. Taken together, these data suggest that PVXCP interacts with the plastocyanin precursor protein and that silencing the expression of this protein leads to reduced PVXCP accumulation in chloroplasts and ameliorates symptom severity in host plants.
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Affiliation(s)
- Y Qiao
- State Key Laboratory of Agrobiotechnology and Department of Plant Pathology, China Agricultural University, Beijing, China
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Użarowska A, Dionisio G, Sarholz B, Piepho HP, Xu M, Ingvardsen CR, Wenzel G, Lübberstedt T. Validation of candidate genes putatively associated with resistance to SCMV and MDMV in maize (Zea mays L.) by expression profiling. BMC PLANT BIOLOGY 2009; 9:15. [PMID: 19187556 PMCID: PMC2669481 DOI: 10.1186/1471-2229-9-15] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Accepted: 02/02/2009] [Indexed: 05/23/2023]
Abstract
BACKGROUND The potyviruses sugarcane mosaic virus (SCMV) and maize dwarf mosaic virus (MDMV) are major pathogens of maize worldwide. Two loci, Scmv1 and Scmv2, have ealier been shown to confer complete resistance to SCMV. Custom-made microarrays containing previously identified SCMV resistance candidate genes and resistance gene analogs were utilised to investigate and validate gene expression and expression patterns of isogenic lines under pathogen infection in order to obtain information about the molecular mechanisms involved in maize-potyvirus interactions. RESULTS By employing time course microarray experiments we identified 68 significantly differentially expressed sequences within the different time points. The majority of differentially expressed genes differed between the near-isogenic line carrying Scmv1 resistance locus at chromosome 6 and the other isogenic lines. Most differentially expressed genes in the SCMV experiment (75%) were identified one hour after virus inoculation, and about one quarter at multiple time points. Furthermore, most of the identified mapped genes were localised outside the Scmv QTL regions. Annotation revealed differential expression of promising pathogenesis-related candidate genes, validated by qRT-PCR, coding for metallothionein-like protein, S-adenosylmethionine synthetase, germin-like protein or 26S ribosomal RNA. CONCLUSION Our study identified putative candidate genes and gene expression patterns related to resistance to SCMV. Moreover, our findings support the effectiveness and reliability of the combination of different expression profiling approaches for the identification and validation of candidate genes. Genes identified in this study represent possible future targets for manipulation of SCMV resistance in maize.
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Affiliation(s)
- Anna Użarowska
- Department of Plant Breeding, Technical University of Munich, Am Hochanger 2, 85350, Freising, Germany
| | - Giuseppe Dionisio
- Faculty of Agricultural Sciences, University of Aarhus, Department of Genetics and Biotechnology, Research Centre Flakkebjerg, Slagelse, DK-4200, Denmark
| | - Barbara Sarholz
- General Motors Powertrain Germany GmbH, 65423, Rüsselsheim, Germany
| | - Hans-Peter Piepho
- Department of Bioinformatics, University of Hohenheim, Fruwirthstrasse 23, 70593, Stuttgart, Germany
| | - Mingliang Xu
- National Maize Improvement Center of China, China Agricultural University, 2 West Yuanmingyuan Road, Beijing, 100094, PR China
| | | | - Gerhard Wenzel
- Department of Plant Breeding, Technical University of Munich, Am Hochanger 2, 85350, Freising, Germany
| | - Thomas Lübberstedt
- Faculty of Agricultural Sciences, University of Aarhus, Department of Genetics and Biotechnology, Research Centre Flakkebjerg, Slagelse, DK-4200, Denmark
- Department of Agronomy, Iowa State University, 1204 Agronomy Hall, 50011 Ames, Iowa, USA
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Seay M, Hayward AP, Tsao J, Dinesh-Kumar SP. Something old, something new: plant innate immunity and autophagy. Curr Top Microbiol Immunol 2009; 335:287-306. [PMID: 19802571 DOI: 10.1007/978-3-642-00302-8_14] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Autophagy performs a variety of established functions during plant growth and development. Recently, autophagy has been further implicated in the regulation of programmed cell death induced during the plant innate immune response. In this chapter we describe specific mechanisms through which autophagy may contribute to a successful defense against pathogen invasion. Accumulating evidence shows that the plant immune system utilizes the chloroplasts as primary sites for the regulation of cell death programs. Viruses also appear to utilize the chloroplast as a site of replication and accumulation, potentially inactivating chloroplast defense signaling in the process. Autophagy-like mechanisms have been observed to target the chloroplast, which we refer to as "chlorophagy," potentially targeting invasive viruses for degradation or regulating chloroplast-based signaling during the immune response. We hypothesize that chlorophagy is significant for the execution of plant immune defenses, during both basal and effector-triggered immunity.
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Affiliation(s)
- Montrell Seay
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520-8103, USA
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Induction of particle polymorphism by cucumber necrosis virus coat protein mutants in vivo. J Virol 2007; 82:1547-57. [PMID: 18032493 DOI: 10.1128/jvi.01976-07] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Cucumber necrosis virus (CNV) particle is a T=3 icosahedron consisting of 180 identical coat protein (CP) subunits. Plants infected with wild-type CNV accumulate a high number of T=3 particles, but other particle forms have not been observed. Particle polymorphism in several T=3 icosahedral viruses has been observed in vitro following the removal of an extended N-terminal region of the CP subunit. In the case of CNV, we have recently described the structure of T=1 particles that accumulate in planta during infection by a CNV mutant (R1+2) in which a large portion of the N-terminal RNA binding domain (R-domain) has been deleted. In this report we further describe properties of this mutant and other CP mutants that produce polymorphic particles. The T=1 particles produced by R1+2 mutants were found to encapsidate a 1.9-kb RNA species as well as smaller RNA species that are similar to previously described CNV defective interfering RNAs. Other R-domain mutants were found to encapsidate a range of specifically sized less-than-full-length CNV RNAs. Mutation of a conserved proline residue in the arm domain near its junction with the shell domain also influenced T=1 particle formation. The proportion of polymorphic particles increased when the mutation was incorporated into R-domain deletion mutants. Our results suggest that both the R-domain and the arm play important roles in the formation of T=3 particles. In addition, the encapsidation of specific CNV RNA species by individual mutants indicates that the R-domain plays a role in the nature of CNV RNA encapsidated in particles.
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Shi Y, Chen J, Hong X, Chen J, Adams MJ. A potyvirus P1 protein interacts with the Rieske Fe/S protein of its host. MOLECULAR PLANT PATHOLOGY 2007; 8:785-90. [PMID: 20507538 DOI: 10.1111/j.1364-3703.2007.00426.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
ABSTRACT Yeast two-hybrid (Y2H) screens were used to test for interactions between the P1 protein of Soybean mosaic virus Pinellia isolate (SMV-P) and a cDNA expression library of its host, the aroid Pinellia ternata. Of the 13 independent interacting clones identified, ten were identical and had an open reading frame predicted to encode a 23.7-kDa protein closely related to the cytochrome b6/f complex Rieske Fe/S genes of plants. The interaction between SMV-P-P1 and the mature Rieske Fe/S protein (without transit peptide) of the host was confirmed by in vitro co-immunoprecipitation of the two proteins. Y2H assays using different parts of the two proteins showed that only the N-terminal part (amino acids 1-82) of SMV-P P1 was responsible for the interaction with the Rieske Fe/S protein and that amino acids 1-33 interacted only with the transit peptide, while amino acids 34-82 could interact with the entire Rieske Fe/S protein. SMV-P P1 also interacted moderately with the Rieske Fe/S protein of its other hosts, soybean and Zantedeschia aethiopica, but weakly with that of the non-host Arabidopsis thaliana. The P1-Rieske Fe/S protein interactions are likely to be involved in symptom development, and the very variable N-terminus of P1 may play an important role in host adaptation.
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Affiliation(s)
- Yuhong Shi
- College of Life Sciences, Zhejiang University, Hangzhou, 310029, People's Republic of China
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Katpally U, Kakani K, Reade R, Dryden K, Rochon D, Smith TJ. Structures of T=1 and T=3 particles of cucumber necrosis virus: evidence of internal scaffolding. J Mol Biol 2006; 365:502-12. [PMID: 17049553 DOI: 10.1016/j.jmb.2006.09.060] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2006] [Revised: 09/07/2006] [Accepted: 09/20/2006] [Indexed: 10/24/2022]
Abstract
Cucumber necrosis virus (CNV) is a member of the genus Tombusvirus, of which tomato bushy stunt virus (TBSV) is the type member. The capsid protein for this group of viruses is composed of three major domains: the R domain, which interacts with the RNA genome: the S domain, which forms the tight capsid shell: and the protruding P domain, which extends approximately 40 Angstrom from the surface. Here, we present the cryo-transmission electron microscopy structures of both the T=1 and T=3 capsids to a resolution of approximately 12 Angstrom. The T=3 capsid is essentially identical with that of TBSV, and the T=1 particles are well described by the A subunit pentons from TBSV. Perhaps most notable is the fact that the T=3 particles have an articulated internal structure with two major internal shells, while the internal core of the T=1 particle is essentially disordered. These internal shells of the T=3 capsid agree extremely well in both dimension and character with published neutron-scattering results. This structure, combined with mutagenesis results in the accompanying article, suggests that the R domain forms an internal icosahedral scaffold that may play a role in T=3 capsid assembly. In addition, the N-terminal region has been shown to be involved in chloroplast targeting. Therefore, this region apparently has remarkably diverse functions that may be distributed unevenly among the quasi-equivalent A, B, and C subunits.
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Affiliation(s)
- Umesh Katpally
- Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, USA
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