1
|
Kwon SJ, Lee YJ, Cho YE, Byun HS, Seo JK. Engineering of stable infectious cDNA constructs of a fluorescently tagged tomato chlorosis virus. Virology 2024; 593:110010. [PMID: 38364352 DOI: 10.1016/j.virol.2024.110010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/15/2024] [Accepted: 01/26/2024] [Indexed: 02/18/2024]
Abstract
Tomato chlorosis virus (ToCV) is an emerging pathogen that cause severe yellow leaf disorder syndrome in tomato plants. In this study, we aimed to generate a recombinant ToCV tagged with green fluorescent protein (GFP) to enable real-time monitoring of viral infection in living plants. Transformation of the full-length cDNA construct of ToCV RNA1 into Escherichia coli resulted in instability issues, which were successfully overcome by inserting a plant intron into RNA1. Subsequently, a GFP tag was engineered into a cDNA construct of ToCV RNA2. The resulting recombinant ToCV-GFP could systemically infect Nicotiana benthamiana plants, and GFP expression was observed along the major veins. Utilizing ToCV-GFP, we also showed that ToCV engages in antagonistic relationships with two different tomato-infecting viruses in mixed infections in N. benthamiana. This study demonstrates the potential of ToCV-GFP as a valuable tool for the visual tracking of infection and movement of criniviruses in living plants.
Collapse
Affiliation(s)
- Sun-Jung Kwon
- Institutes of Green Bio Science and Technology, Seoul National University, Pyeongchang 25354, Republic of Korea
| | - Ye-Ji Lee
- Crop Protection Division, National Institute of Agricultural Sciences, Rural Development Administration, Wanju 55365, Republic of Korea
| | - Young-Eun Cho
- Institutes of Green Bio Science and Technology, Seoul National University, Pyeongchang 25354, Republic of Korea
| | - Hee-Seong Byun
- Crop Protection Division, National Institute of Agricultural Sciences, Rural Development Administration, Wanju 55365, Republic of Korea
| | - Jang-Kyun Seo
- Institutes of Green Bio Science and Technology, Seoul National University, Pyeongchang 25354, Republic of Korea; Department of International Agricultural Technology, Seoul National University, Pyeongchang 25354, Republic of Korea.
| |
Collapse
|
2
|
Liu S, Han Y, Li WX, Ding SW. Infection Defects of RNA and DNA Viruses Induced by Antiviral RNA Interference. Microbiol Mol Biol Rev 2023; 87:e0003522. [PMID: 37052496 PMCID: PMC10304667 DOI: 10.1128/mmbr.00035-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023] Open
Abstract
Immune recognition of viral genome-derived double-stranded RNA (dsRNA) molecules and their subsequent processing into small interfering RNAs (siRNAs) in plants, invertebrates, and mammals trigger specific antiviral immunity known as antiviral RNA interference (RNAi). Immune sensing of viral dsRNA is sequence-independent, and most regions of viral RNAs are targeted by virus-derived siRNAs which extensively overlap in sequence. Thus, the high mutation rates of viruses do not drive immune escape from antiviral RNAi, in contrast to other mechanisms involving specific virus recognition by host immune proteins such as antibodies and resistance (R) proteins in mammals and plants, respectively. Instead, viruses actively suppress antiviral RNAi at various key steps with a group of proteins known as viral suppressors of RNAi (VSRs). Some VSRs are so effective in virus counter-defense that potent inhibition of virus infection by antiviral RNAi is undetectable unless the cognate VSR is rendered nonexpressing or nonfunctional. Since viral proteins are often multifunctional, resistance phenotypes of antiviral RNAi are accurately defined by those infection defects of VSR-deletion mutant viruses that are efficiently rescued by host deficiency in antiviral RNAi. Here, we review and discuss in vivo infection defects of VSR-deficient RNA and DNA viruses resulting from the actions of host antiviral RNAi in model systems.
Collapse
Affiliation(s)
- Si Liu
- Department of Microbiology & Plant Pathology, University of California, Riverside, California, USA
- Center for Plant Cell Biology, Institute for Integrative Genome Biology, University of California, Riverside, California, USA
| | - Yanhong Han
- Vector-borne Virus Research Center, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Wan-Xiang Li
- Department of Microbiology & Plant Pathology, University of California, Riverside, California, USA
- Center for Plant Cell Biology, Institute for Integrative Genome Biology, University of California, Riverside, California, USA
| | - Shou-Wei Ding
- Department of Microbiology & Plant Pathology, University of California, Riverside, California, USA
- Center for Plant Cell Biology, Institute for Integrative Genome Biology, University of California, Riverside, California, USA
| |
Collapse
|
3
|
Ding SW. Transgene Silencing, RNA Interference, and the Antiviral Defense Mechanism Directed by Small Interfering RNAs. PHYTOPATHOLOGY 2023; 113:616-625. [PMID: 36441873 DOI: 10.1094/phyto-10-22-0358-ia] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
One important discovery in plant pathology over recent decades is the natural antiviral defense mechanism mediated by RNA interference (RNAi). In antiviral RNAi, virus infection triggers Dicer processing of virus-specific double-stranded RNA into small interfering RNAs (siRNAs). Frequently, further amplified by host enzyme and cofactors, these virus-derived siRNAs direct specific virus clearance in an Argonaute protein-containing effector complex. The siRNAs derived from viruses and viroids accumulate to very high levels during infection. Because they overlap extensively in nucleotide sequence, this allows for deep sequencing and bioinformatics assembly of total small RNAs for rapid discovery and identification of viruses and viroids. Antiviral RNAi acts as the primary defense mechanism against both RNA and DNA viruses in plants, yet viruses still successfully infect plants. They do so because all currently recognized plant viruses combat the RNAi response by encoding at least one protein as a viral suppressor of RNAi (VSR) required for infection, even though plant viruses have small genome sizes with a limited coding capacity. This review article will recapitulate the key findings that have revealed the genetic pathway for the biogenesis and antiviral activity of viral siRNAs and the specific role of VSRs in infection by antiviral RNAi suppression. Moreover, early pioneering studies on transgene silencing, RNAi, and virus-plant/virus-virus interactions paved the road to the discovery of antiviral RNAi.
Collapse
Affiliation(s)
- Shou-Wei Ding
- Department of Microbiology & Plant Pathology and Center for Plant Cell Biology, Institute for Integrative Genome Biology, University of California, Riverside, CA
| |
Collapse
|
4
|
Bradamante G, Mittelsten Scheid O, Incarbone M. Under siege: virus control in plant meristems and progeny. THE PLANT CELL 2021; 33:2523-2537. [PMID: 34015140 PMCID: PMC8408453 DOI: 10.1093/plcell/koab140] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 05/14/2021] [Indexed: 05/29/2023]
Abstract
In the arms race between plants and viruses, two frontiers have been utilized for decades to combat viral infections in agriculture. First, many pathogenic viruses are excluded from plant meristems, which allows the regeneration of virus-free plant material by tissue culture. Second, vertical transmission of viruses to the host progeny is often inefficient, thereby reducing the danger of viral transmission through seeds. Numerous reports point to the existence of tightly linked meristematic and transgenerational antiviral barriers that remain poorly understood. In this review, we summarize the current understanding of the molecular mechanisms that exclude viruses from plant stem cells and progeny. We also discuss the evidence connecting viral invasion of meristematic cells and the ability of plants to recover from acute infections. Research spanning decades performed on a variety of virus/host combinations has made clear that, beside morphological barriers, RNA interference (RNAi) plays a crucial role in preventing-or allowing-meristem invasion and vertical transmission. How a virus interacts with plant RNAi pathways in the meristem has profound effects on its symptomatology, persistence, replication rates, and, ultimately, entry into the host progeny.
Collapse
Affiliation(s)
- Gabriele Bradamante
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria
| | - Ortrun Mittelsten Scheid
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria
| | - Marco Incarbone
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria
| |
Collapse
|
5
|
Tahmasebi A, Khahani B, Tavakol E, Afsharifar A, Shahid MS. Microarray analysis of Arabidopsis thaliana exposed to single and mixed infections with Cucumber mosaic virus and turnip viruses. PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2021; 27:11-27. [PMID: 33627959 PMCID: PMC7873207 DOI: 10.1007/s12298-021-00925-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 12/16/2020] [Accepted: 01/03/2021] [Indexed: 05/05/2023]
Abstract
UNLABELLED Cucumber mosaic virus (CMV), Turnip mosaic virus (TuMV) and Turnip crinkle virus (TCV) are important plant infecting viruses. In the present study, whole transcriptome alteration of Arabidopsis thaliana in response to CMV, TuMV and TCV, individual as well as mixed infections of CMV and TuMV/CMV and TCV were investigated using microarray data. In response to CMV, TuMV and TCV infections, a total of 2517, 3985 and 277 specific differentially expressed genes (DEGs) were up-regulated, while 2615, 3620 and 243 specific DEGs were down-regulated, respectively. The number of 1222 and 30 common DEGs were up-regulated during CMV and TuMV as well as CMV and TCV infections, while 914 and 24 common DEGs were respectively down-regulated. Genes encoding immune response mediators, signal transducer activity, signaling and stress response functions were among the most significantly upregulated genes during CMV and TuMV or CMV and TCV mixed infections. The NAC, C3H, C2H2, WRKY and bZIP were the most commonly presented transcription factor (TF) families in CMV and TuMV infection, while AP2-EREBP and C3H were the TF families involved in CMV and TCV infections. Moreover, analysis of miRNAs during CMV and TuMV and CMV and TCV infections have demonstrated the role of miRNAs in the down regulation of host genes in response to viral infections. These results identified the commonly expressed virus-responsive genes and pathways during plant-virus interaction which might develop novel antiviral strategies for improving plant resistance to mixed viral infections. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s12298-021-00925-3.
Collapse
Affiliation(s)
- Aminallah Tahmasebi
- Department of Agriculture, Minab Higher Education Center, University of Hormozgan, Bandar Abbas, 7916193145 Iran
- Plant Protection Research Group, University of Hormozgan, Bandar Abbas, Iran
| | - Bahman Khahani
- Department of Plant Genetics and Production, College of Agriculture, Shiraz University, Shiraz, Iran
| | - Elahe Tavakol
- Department of Plant Genetics and Production, College of Agriculture, Shiraz University, Shiraz, Iran
| | | | - Muhammad Shafiq Shahid
- Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Oman
| |
Collapse
|
6
|
Niu S, Guo S, Tewary SK, Wong SM. Effects of deletion at the TTTSTTT motif of Hibiscus latent Singapore virus coat protein on viral replication and long-distance movement. Virology 2019; 526:13-21. [PMID: 30317102 DOI: 10.1016/j.virol.2018.09.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 09/29/2018] [Accepted: 09/29/2018] [Indexed: 11/24/2022]
Abstract
Hibiscus latent Singapore virus (HLSV) mutant HLSV-22A could not express coat protein (CP) nor infect plants systemically (Niu et al., 2015). In this study, a serine- and threonine-rich motif TTTSTTT at the C-terminus of HLSV CP was found to be involved in virus replication and systemic movement. Deletion the last amino acid residue in HLSV-22A led to a more rapid virus replication, but with delayed systemic movement. When the RNA structure in TTTSTTT motif was altered, while keeping its amino acids unchanged, mutants HLSV-87A-mmSL and HLSV-22A-mmSL showed no change in viral replication. These results indicated that the unique TTTSTTT motif is associated with virus replication and systemic movement. Deletion but not substitution of amino acid(s) at the C-terminus of TTTSTTT motif of HLSV CP with short internal poly(A) track enhanced virus replication, whereas the virus with a longer internal poly(A) tract of 87 A showed delayed systemic movement (147 words).
Collapse
Affiliation(s)
- Shengniao Niu
- Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Song Guo
- Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Sunil Kumar Tewary
- Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Sek-Man Wong
- Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore; Temasek Life Sciences Laboratory, 1 Research Link, Singapore 117604, Singapore; National University of Singapore (Suzhou) Research Institute, Suzhou, Jiangsu, China 215123.
| |
Collapse
|
7
|
Navarro JA, Pallás V. An Update on the Intracellular and Intercellular Trafficking of Carmoviruses. FRONTIERS IN PLANT SCIENCE 2017; 8:1801. [PMID: 29093729 PMCID: PMC5651262 DOI: 10.3389/fpls.2017.01801] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 10/04/2017] [Indexed: 05/03/2023]
Abstract
Despite harboring the smallest genomes among plant RNA viruses, carmoviruses have emerged as an ideal model system for studying essential steps of the viral cycle including intracellular and intercellular trafficking. Two small movement proteins, formerly known as double gene block proteins (DGBp1 and DGBp2), have been involved in the movement throughout the plant of some members of carmovirus genera. DGBp1 RNA-binding capability was indispensable for cell-to-cell movement indicating that viral genomes must interact with DGBp1 to be transported. Further investigation on Melon necrotic spot virus (MNSV) DGBp1 subcellular localization and dynamics also supported this idea as this protein showed an actin-dependent movement along microfilaments and accumulated at the cellular periphery. Regarding DGBp2, subcellular localization studies showed that MNSV and Pelargonium flower break virus DGBp2s were inserted into the endoplasmic reticulum (ER) membrane but only MNSV DGBp2 trafficked to plasmodesmata (PD) via the Golgi apparatus through a COPII-dependent pathway. DGBp2 function is still unknown but its localization at PD was a requisite for an efficient cell-to-cell movement. It is also known that MNSV infection can induce a dramatic reorganization of mitochondria resulting in anomalous organelles containing viral RNAs. These putative viral factories were frequently found associated with the ER near the PD leading to the possibility that MNSV movement and replication could be spatially linked. Here, we update the current knowledge of the plant endomembrane system involvement in carmovirus intra- and intercellular movement and the tentative model proposed for MNSV transport within plant cells.
Collapse
|
8
|
Dall'Ara M, Ratti C, Bouzoubaa SE, Gilmer D. Ins and Outs of Multipartite Positive-Strand RNA Plant Viruses: Packaging versus Systemic Spread. Viruses 2016; 8:E228. [PMID: 27548199 PMCID: PMC4997590 DOI: 10.3390/v8080228] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 07/29/2016] [Accepted: 08/09/2016] [Indexed: 11/16/2022] Open
Abstract
Viruses possessing a non-segmented genome require a specific recognition of their nucleic acid to ensure its protection in a capsid. A similar feature exists for viruses having a segmented genome, usually consisting of viral genomic segments joined together into one viral entity. While this appears as a rule for animal viruses, the majority of segmented plant viruses package their genomic segments individually. To ensure a productive infection, all viral particles and thereby all segments have to be present in the same cell. Progression of the virus within the plant requires as well a concerted genome preservation to avoid loss of function. In this review, we will discuss the "life aspects" of chosen phytoviruses and argue for the existence of RNA-RNA interactions that drive the preservation of viral genome integrity while the virus progresses in the plant.
Collapse
Affiliation(s)
- Mattia Dall'Ara
- Institut de Biologie Moléculaire des Plantes, Integrative Virology, CNRS UPR2367, Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France.
- Dipartimento di Scienze Agrarie, Area Patologia Vegetale, Università di Bologna, Viale Fanin 40, 40127 Bologna, Italy.
| | - Claudio Ratti
- Dipartimento di Scienze Agrarie, Area Patologia Vegetale, Università di Bologna, Viale Fanin 40, 40127 Bologna, Italy.
| | - Salah E Bouzoubaa
- Institut de Biologie Moléculaire des Plantes, Integrative Virology, CNRS UPR2367, Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France.
| | - David Gilmer
- Institut de Biologie Moléculaire des Plantes, Integrative Virology, CNRS UPR2367, Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France.
| |
Collapse
|
9
|
Li Y, Zhang J, Zhao F, Ren H, Zhu L, Xi D, Lin H. The interaction between Turnip crinkle virus p38 and Cucumber mosaic virus 2b and its critical domains. Virus Res 2016; 222:94-105. [PMID: 27288723 DOI: 10.1016/j.virusres.2016.06.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 06/05/2016] [Accepted: 06/08/2016] [Indexed: 11/28/2022]
Abstract
Cross protection is a common phenomenon among closely related strain viruses in co-infected plants. However, unrelated viruses, Turnip crinkle virus (TCV) and Cucumber mosaic virus (CMV), also show an antagonistic effect in co-infected Arabidopsis plants. In many cases, viral suppressors of RNA silencing (VSRs) have important roles in the interactions between viruses in mixed infections. CMV 2b and TCV p38 are multifunctional proteins and both of them are well characterized VSRs and have important roles in operation synergistic interactions with other viruses. Here, we demonstrated antagonistic effects of TCV toward CMV and showed that RNA silencing-mediated resistance protein, RCY1 and TCV-interacting protein (TIP) of Arabidopsis plants did not affect this antagonism effect. We further showed that TCV p38 and CMV 2b could interact with each other in vivo but not in vitro. Further mutational analysis showed that C-terminal of 2b and middle domains of p38 had more important roles in the interaction between the two viruses.
Collapse
Affiliation(s)
- Yanan Li
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, Sichuan University, Chengdu 610064, China
| | - Jing Zhang
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, Sichuan University, Chengdu 610064, China
| | - Feifei Zhao
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, Sichuan University, Chengdu 610064, China
| | - Han Ren
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, Sichuan University, Chengdu 610064, China
| | - Lin Zhu
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, Sichuan University, Chengdu 610064, China
| | - Dehui Xi
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, Sichuan University, Chengdu 610064, China.
| | - Honghui Lin
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, Sichuan University, Chengdu 610064, China.
| |
Collapse
|
10
|
Scheets K. Analysis of gene functions in Maize chlorotic mottle virus. Virus Res 2016; 222:71-79. [PMID: 27242072 DOI: 10.1016/j.virusres.2016.04.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 04/11/2016] [Accepted: 04/18/2016] [Indexed: 12/16/2022]
Abstract
Gene functions of strains of Maize chlorotic mottle virus, which comprises the monotypic genus Machlomovirus, have not been previously identified. In this study mutagenesis of the seven genes encoded in maize chlorotic mottle virus (MCMV) showed that the genes with positional and sequence similarity to their homologs in viruses of related tombusvirid genera had similar functions. p50 and its readthrough protein p111 are the only proteins required for replication in maize protoplasts, and they function at a low level in trans. Two movement proteins, p7a and p7b, and coat protein, encoded on subgenomic RNA1, are required for cell-to-cell movement in maize, and p7a and p7b function in trans. A unique protein, p31, expressed as a readthrough extension of p7a, is required for efficient systemic infection. The 5' proximal MCMV gene encodes a unique 32kDa protein that is not required for replication or movement. Transcripts lacking p32 expression accumulate to about 1/3 the level of wild type transcripts in protoplasts and produce delayed, mild infections in maize plants. Additional studies on p32, p31 and the unique amino-terminal region of p50 are needed to further characterize the life cycle of this unique tombusvirid.
Collapse
Affiliation(s)
- Kay Scheets
- Department of Plant Biology, Ecology, and Evolution, 301 Physical Sciences, Oklahoma State University, Stillwater, OK, 74078-3013, USA.
| |
Collapse
|
11
|
A nuclear fraction of turnip crinkle virus capsid protein is important for elicitation of the host resistance response. Virus Res 2015; 210:264-70. [PMID: 26299399 DOI: 10.1016/j.virusres.2015.08.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 08/11/2015] [Accepted: 08/15/2015] [Indexed: 11/21/2022]
Abstract
The N-terminal 25 amino acids (AAs) of turnip crinkle virus (TCV) capsid protein (CP) are recognized by the resistance protein HRT to trigger a hypersensitive response (HR) and systemic resistance to TCV infection. This same region of TCV CP also contains a motif that interacts with the transcription factor TIP, as well as a nuclear localization signal (NLS). However, it is not yet known whether nuclear localization of TCV CP is needed for the induction of HRT-mediated HR and resistance. Here we present new evidence suggesting a tight correlation between nuclear inclusions formed by CP and the manifestation of HR. We show that a fraction of TCV CP localized to cell nuclei to form discrete inclusion-like structures, and a mutated CP (R6A) known to abolish HR failed to form nuclear inclusions. Notably, TIP-CP interaction augments the inclusion-forming activity of CP by tethering inclusions to the nuclear membrane. This TIP-mediated augmentation is also critical for HR resistance, as another CP mutant (R8A) known to elicit a less restrictive HR, though still self-associated into nuclear inclusions, failed to direct inclusions to the nuclear membrane due to its inability to interact with TIP. Finally, exclusion of CP from cell nuclei abolished induction of HR. Together, these results uncovered a strong correlation between nuclear localization and nuclear inclusion formation by TCV CP and induction of HR, and suggest that CP nuclear inclusions could be the key trigger of the HRT-dependent, yet TIP-reinforced, resistance to TCV.
Collapse
|
12
|
Tatineni S, McMechan AJ, Bartels M, Hein GL, Graybosch RA. In Vitro Transcripts of Wild-Type and Fluorescent Protein-Tagged Triticum mosaic virus (Family Potyviridae) are Biologically Active in Wheat. PHYTOPATHOLOGY 2015; 105:1496-505. [PMID: 26214124 DOI: 10.1094/phyto-06-15-0138-r] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Triticum mosaic virus (TriMV) (genus Poacevirus, family Potyviridae) is a recently described eriophyid mite-transmitted wheat virus. In vitro RNA transcripts generated from full-length cDNA clones of TriMV proved infectious on wheat. Wheat seedlings inoculated with in vitro transcripts elicited mosaic and mottling symptoms similar to the wild-type virus, and the progeny virus was efficiently transmitted by wheat curl mites, indicating that the cloned virus retained pathogenicity, movement, and wheat curl mite transmission characteristics. A series of TriMV-based expression vectors was constructed by engineering a green fluorescent protein (GFP) or red fluorescent protein (RFP) open reading frame with homologous NIa-Pro cleavage peptides between the P1 and HC-Pro cistrons. We found that GFP-tagged TriMV with seven or nine amino acid cleavage peptides efficiently processed GFP from HC-Pro. TriMV-GFP vectors were stable in wheat for more than 120 days and for six serial passages at 14-day intervals by mechanical inoculation and were transmitted by wheat curl mites similarly to the wild-type virus. Fluorescent protein-tagged TriMV was observed in wheat leaves, stems, and crowns. The availability of fluorescent protein-tagged TriMV will facilitate the examination of virus movement and distribution in cereal hosts and the mechanisms of cross protection and synergistic interactions between TriMV and Wheat streak mosaic virus.
Collapse
Affiliation(s)
- Satyanarayana Tatineni
- First author: United States Department of Agriculture-Agricultural Research Service (USDA-ARS) and Department of Plant Pathology; second and fourth authors: Department of Entomology; third author: USDA-ARS; and fifth author: USDA-ARS and Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln 68583
| | - Anthony J McMechan
- First author: United States Department of Agriculture-Agricultural Research Service (USDA-ARS) and Department of Plant Pathology; second and fourth authors: Department of Entomology; third author: USDA-ARS; and fifth author: USDA-ARS and Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln 68583
| | - Melissa Bartels
- First author: United States Department of Agriculture-Agricultural Research Service (USDA-ARS) and Department of Plant Pathology; second and fourth authors: Department of Entomology; third author: USDA-ARS; and fifth author: USDA-ARS and Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln 68583
| | - Gary L Hein
- First author: United States Department of Agriculture-Agricultural Research Service (USDA-ARS) and Department of Plant Pathology; second and fourth authors: Department of Entomology; third author: USDA-ARS; and fifth author: USDA-ARS and Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln 68583
| | - Robert A Graybosch
- First author: United States Department of Agriculture-Agricultural Research Service (USDA-ARS) and Department of Plant Pathology; second and fourth authors: Department of Entomology; third author: USDA-ARS; and fifth author: USDA-ARS and Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln 68583
| |
Collapse
|
13
|
Matevz R, Florence F, Michel T, Ion GA, Agnès D, Laurent G, Maja K, David D, Kristina G, Emmanuel J, Maja R. Fluorescently Tagged Potato virus Y: A Versatile Tool for Functional Analysis of Plant-Virus Interactions. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:739-50. [PMID: 25761209 DOI: 10.1094/mpmi-07-14-0218-ta] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Potato virus Y (PVY) is an economically important plant virus that infects Solanaceous crops such as tobacco and potato. To date, studies into the localization and movement of PVY in plants have been limited to detection of viral RNA or proteins ex vivo. Here, a PVY N605 isolate was tagged with green fluorescent protein (GFP), characterized and used for in vivo tracking. In Nicotiana tabacum cv. Xanthi, PVY N605-GFP was biologically comparable to nontagged PVY N605, stable through three plant-to-plant passages and persisted for four months in infected plants. GFP was detected before symptoms and fluorescence intensity correlated with PVY RNA concentrations. PVY N605-GFP provided in vivo tracking of long-distance movement, allowing estimation of the cell-to-cell movement rate of PVY in N. tabacum cv. Xanthi (7.1 ± 1.5 cells per hour). PVY N605-GFP was adequately stable in Solanum tuberosum cvs. Désirée and NahG-Désirée and able to infect S. tuberosum cvs. Bintje and Bea, Nicotiana benthamiana, and wild potato relatives. PVY N605-GFP is therefore a powerful tool for future studies of PVY-host interactions, such as functional analysis of viral and plant genes involved in viral movement.
Collapse
Affiliation(s)
- Rupar Matevz
- 1 National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Faurez Florence
- 2 INRA, UMR 1349 IGEPP, Domaine de la Motte F-35653, Le Rheu, France
- 3 FN3PT/RD3PT, 43-45 rue de Naples, 75008 Paris, France
| | - Tribodet Michel
- 2 INRA, UMR 1349 IGEPP, Domaine de la Motte F-35653, Le Rheu, France
| | | | - Delaunay Agnès
- 4 INRA-CIRAD-Montpellier SupAgro, UMR-BGPI TA A-54/K, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France
| | - Glais Laurent
- 2 INRA, UMR 1349 IGEPP, Domaine de la Motte F-35653, Le Rheu, France
- 3 FN3PT/RD3PT, 43-45 rue de Naples, 75008 Paris, France
| | - Kriznik Maja
- 1 National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Dobnik David
- 1 National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Gruden Kristina
- 1 National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Jacquot Emmanuel
- 4 INRA-CIRAD-Montpellier SupAgro, UMR-BGPI TA A-54/K, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France
| | - Ravnikar Maja
- 1 National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia
| |
Collapse
|
14
|
Kang SH, Qu F, Morris TJ. A spectrum of HRT-dependent hypersensitive responses elicited by the 52 amino acid N-terminus of turnip crinkle virus capsid protein and its mutants. Virus Res 2015; 200:30-4. [PMID: 25656064 DOI: 10.1016/j.virusres.2015.01.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 01/21/2015] [Accepted: 01/24/2015] [Indexed: 11/28/2022]
Abstract
The capsid protein (CP) of turnip crinkle virus (TCV) is the elicitor of hypersensitive response (HR) and resistance mediated by the resistance protein HRT in the Di-17 ecotype of Arabidopsis. Here we identified the N-terminal 52-amino-acid R domain of TCV CP as the elicitor of HRT-dependent HR in Nicotiana benthamiana. Mutating this domain at position 6 (R6A), but not at positions 8 (R8A) or 14 (G14A), abolished HR in N. benthamiana. However, on Di-17 Arabidopsis leaves only R8A R domain elicited visible epidermal HR. When incorporated in infectious TCV RNAs, R8A and G14A mutations exerted dramatically different effects in Di-17 plants, as R8A caused systemic cell death whereas G14A led to complete restriction of the mutant virus. This continual spectrum of HR and resistance responses elicited by various R domain mutants suggests that the CP-HRT interaction could be perturbed by conformational changes in the R domain of TCV CP.
Collapse
Affiliation(s)
- Sung-Hwan Kang
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, United States
| | - Feng Qu
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, United States; Department of Plant Pathology, The Ohio State University, Wooster, OH 44691, United States.
| | - T Jack Morris
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, United States.
| |
Collapse
|
15
|
Niu S, Gil-Salas FM, Tewary SK, Samales AK, Johnson J, Swaminathan K, Wong SM. Hibiscus chlorotic ringspot virus coat protein is essential for cell-to-cell and long-distance movement but not for viral RNA replication. PLoS One 2014; 9:e113347. [PMID: 25402344 PMCID: PMC4234673 DOI: 10.1371/journal.pone.0113347] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 10/22/2014] [Indexed: 11/29/2022] Open
Abstract
Hibiscus chlorotic ringspot virus (HCRSV) is a member of the genus Carmovirus in the family Tombusviridae. In order to study its coat protein (CP) functions on virus replication and movement in kenaf (Hibiscus cannabinus L.), two HCRSV mutants, designated as p2590 (A to G) in which the first start codon ATG was replaced with GTG and p2776 (C to G) in which proline 63 was replaced with alanine, were constructed. In vitro transcripts of p2590 (A to G) were able to replicate to a similar level as wild type without CP expression in kenaf protoplasts. However, its cell-to-cell movement was not detected in the inoculated kenaf cotyledons. Structurally the proline 63 in subunit C acts as a kink for β-annulus formation during virion assembly. Progeny of transcripts derived from p2776 (C to G) was able to move from cell-to-cell in inoculated cotyledons but its long-distance movement was not detected. Virions were not observed in partially purified mutant virus samples isolated from 2776 (C to G) inoculated cotyledons. Removal of the N-terminal 77 amino acids of HCRSV CP by trypsin digestion of purified wild type HCRSV virions resulted in only T = 1 empty virus-like particles. Taken together, HCRSV CP is dispensable for viral RNA replication but essential for cell-to-cell movement, and virion is required for the virus systemic movement. The proline 63 is crucial for HCRSV virion assembly in kenaf plants and the N-terminal 77 amino acids including the β-annulus domain is required in T = 3 assembly in vitro.
Collapse
Affiliation(s)
- Shengniao Niu
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, Hainan, China
| | - Francisco M. Gil-Salas
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- Instituto Andaluz de Investigación y Formación Agraria, Pesquera, Alimentaria y de la Producción Ecológica, Almería, Spain
| | - Sunil Kumar Tewary
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | | | - John Johnson
- Department of Molecular Biology, The Scripps Research Institute, California, United States of America
| | | | - Sek-Man Wong
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- Temasek Life Sciences Laboratory, Singapore, Singapore
- National University of Singapore Suzhou Research Institute, Suzhou Industrial Park, Jiangsu, China
| |
Collapse
|
16
|
The capsid protein p38 of turnip crinkle virus is associated with the suppression of cucumber mosaic virus in Arabidopsis thaliana co-infected with cucumber mosaic virus and turnip crinkle virus. Virology 2014; 462-463:71-80. [DOI: 10.1016/j.virol.2014.05.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 05/09/2014] [Accepted: 05/27/2014] [Indexed: 11/20/2022]
|
17
|
Abstract
The genus Dianthovirus is one of eight genera in the family Tombusviridae. All the genera have monopartite positive-stranded RNA genomes, except the dianthoviruses which have bipartite genomes. The dianthoviruses are distributed worldwide. Although they share common structural features with the other Tombusviridae viruses in their virions and the terminal structure of the genomic RNAs, the bipartite nature of the dianthovirus genome offers an ideal experimental system with which to study basic issues of virology. The two genomic RNAs seem to use distinct strategies to regulate their translation, transcription, genome replication, genome packaging, and cell-to-cell movement during infection. This review summarizes the current state of our knowledge of the dianthoviruses, with its main emphasis on the molecular biology of the virus, including the viral and host factors required for its infection of host plants. The epidemiology of the virus and the possible viral impacts on agriculture and the environment are also discussed.
Collapse
Affiliation(s)
- Tetsuro Okuno
- Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, Japan.
| | | |
Collapse
|
18
|
Qin C, Shi N, Gu M, Zhang H, Li B, Shen J, Mohammed A, Ryabov E, Li C, Wang H, Liu Y, Osman T, Vatish M, Hong Y. Involvement of RDR6 in short-range intercellular RNA silencing in Nicotiana benthamiana. Sci Rep 2012; 2:467. [PMID: 22737403 PMCID: PMC3381291 DOI: 10.1038/srep00467] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 06/11/2012] [Indexed: 01/02/2023] Open
Abstract
In plants, non-cell autonomous RNA silencing spreads between cells and over long distances. Recent work has revealed insight on the genetic and molecular components essential for cell-to-cell movement of RNA silencing in Arabidopsis. Using a local RNA silencing assay, we report on a distinct mechanism that may govern the short-range (6-10 cell) trafficking of virus-induced RNA silencing from epidermal to neighbouring palisade and spongy parenchyma cells in Nicotiana benthamiana. This process involves a previously unrecognised function of the RNA-dependent RNA polymerase 6 (RDR6) gene. Our data suggest that plants may have evolved distinct genetic controls in intercellular RNA silencing among different types of cells.
Collapse
Affiliation(s)
- Cheng Qin
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
- These authors contributed equally to this work
| | - Nongnong Shi
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
- Warwick HRI, University of Warwick, Warwick CV35 9EF, UK
- These authors contributed equally to this work
| | - Mei Gu
- Clinical Sciences Research Institute, University of Warwick, Coventry CV2 2DX, UK
- These authors contributed equally to this work
| | - Hang Zhang
- Warwick HRI, University of Warwick, Warwick CV35 9EF, UK
- Chengdu Rongsheng Pharmaceuticals, Chengdu 610041, China
| | - Bin Li
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Jiajia Shen
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Atef Mohammed
- Warwick HRI, University of Warwick, Warwick CV35 9EF, UK
- Department of Botany, Faculty of Agriculture, Fayoum University, Fayoum 63514, Egypt
| | - Eugene Ryabov
- Warwick HRI, University of Warwick, Warwick CV35 9EF, UK
| | - Chunyang Li
- Warwick HRI, University of Warwick, Warwick CV35 9EF, UK
- Chengdu Rongsheng Pharmaceuticals, Chengdu 610041, China
| | - Huizhong Wang
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Yule Liu
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Toba Osman
- Warwick HRI, University of Warwick, Warwick CV35 9EF, UK
- Department of Botany, Faculty of Agriculture, Fayoum University, Fayoum 63514, Egypt
| | - Manu Vatish
- Clinical Sciences Research Institute, University of Warwick, Coventry CV2 2DX, UK
| | - Yiguo Hong
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
- Warwick HRI, University of Warwick, Warwick CV35 9EF, UK
| |
Collapse
|
19
|
Parallels and distinctions in the direct cell-to-cell spread of the plant and animal viruses. Curr Opin Virol 2011; 1:403-9. [PMID: 22440842 DOI: 10.1016/j.coviro.2011.09.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 09/23/2011] [Indexed: 01/07/2023]
Abstract
The paradigm that viruses can move directly, and in some cases covertly, between contacting target cells is now well established for several virus families. The underlying mechanisms of cell-to-cell spread, however, remain to be fully elucidated and may differ substantially depending on the viral exit/entry route and the cellular tropism. Here, two divergent cell-to-cell spread mechanisms are exemplified: firstly by human retroviruses, which rely upon transient adhesive structures that form between polarized immune cells termed virological synapses, and secondly by herpesviruses that depend predominantly on pre-existing stable cellular contacts, but may also form virological synapses. Plant viruses can also spread directly between contacting cells, but are obliged by the rigid host cell wall to move across pore structures termed plasmodesmata. This review will focus primarily on recent advances in our understanding of animal virus cell-to-cell spread using examples from these two virus families to highlight differences and similarities, and will conclude by comparing and contrasting the cell-to-cell spread of animal and plant viruses.
Collapse
|
20
|
The capsid protein of Turnip crinkle virus overcomes two separate defense barriers to facilitate systemic movement of the virus in Arabidopsis. J Virol 2010; 84:7793-802. [PMID: 20504923 DOI: 10.1128/jvi.02643-09] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The capsid protein (CP) of Turnip crinkle virus (TCV) is a multifunctional protein needed for virus assembly, suppression of RNA silencing-based antiviral defense, and long-distance movement in infected plants. In this report, we have examined genetic requirements for the different functions of TCV CP and evaluated the interdependence of these functions. A series of TCV mutants containing alterations in the CP coding region were generated. These alterations range from single-amino-acid substitutions and domain truncations to knockouts of CP translation. The latter category also contained two constructs in which the CP coding region was replaced by either the cDNA of a silencing suppressor of a different virus or that of green fluorescent protein. These mutants were used to infect Arabidopsis plants with diminished antiviral silencing capability (dcl2 dcl3 dcl4 plants). There was a strong correlation between the ability of mutants to reach systemic leaves and the silencing suppressor activity of mutant CP. Virus particles were not essential for entry of the viral genome into vascular bundles in the inoculated leaves in the absence of antiviral silencing. However, virus particles were necessary for egress of the viral genome from the vasculature of systemic leaves. Our experiments demonstrate that TCV CP not only allows the viral genome to access the systemic movement channel through silencing suppression but also ensures its smooth egress by way of assembled virus particles. These results illustrate that efficient long-distance movement of TCV requires both functions afforded by the CP.
Collapse
|
21
|
Abstract
Plant viral infection and spread depends on the successful introduction of a virus into a cell of a compatible host, followed by replication and cell-to-cell transport. The movement proteins (MPs) p8 and p9 of Turnip crinkle virus are required for cell-to-cell movement of the virus. We have examined the membrane association of p9 and found that it is an integral membrane protein with a defined topology in the endoplasmic reticulum (ER) membrane. Furthermore, we have used a site-specific photo-cross-linking strategy to study the membrane integration of the protein at the initial stages of its biosynthetic process. This process is cotranslational and proceeds through the signal recognition particle and the translocon complex.
Collapse
|
22
|
Genovés A, Navarro JA, Pallás V. A self-interacting carmovirus movement protein plays a role in binding of viral RNA during the cell-to-cell movement and shows an actin cytoskeleton dependent location in cell periphery. Virology 2009; 395:133-42. [PMID: 19796783 DOI: 10.1016/j.virol.2009.08.042] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 08/12/2009] [Accepted: 08/30/2009] [Indexed: 10/20/2022]
Abstract
The p7A of Melon necrotic spot virus has been described to be a RNA-binding movement protein essential for cell-to-cell movement but its role in this process is still unknown. Here, we found that primary and secondary structure elements on p7A appear to form a composite RNA-binding site required for both RNA interaction and cell-to-cell movement in plants indicating a direct correlation between these activities. Furthermore, we found that fluorescent-tagged p7A was distributed in punctuate structures at the cell periphery but also in motile cytoplasmic inclusion bodies which were in close association with the actin MFs and most likely generated by self-interacting p7A molecules as shown by BiFC assays. Consistently, the p7A subcellular distribution was revealed to be sensitive to the actin inhibitor, latrunculin B. The involvement of the RNA-binding capabilities and the subcellular location of the p7A in the intracellular and intercellular virus movement is discussed.
Collapse
Affiliation(s)
- Ainhoa Genovés
- Instituto de Biología Molecular y Celular de Plantas (IBMCP). UPV-CSIC, Avda. de los Naranjos s/n, Valencia, Spain.
| | | | | |
Collapse
|
23
|
Alvarado V, Scholthof HB. Plant responses against invasive nucleic acids: RNA silencing and its suppression by plant viral pathogens. Semin Cell Dev Biol 2009; 20:1032-40. [PMID: 19524057 DOI: 10.1016/j.semcdb.2009.06.001] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 05/29/2009] [Accepted: 06/04/2009] [Indexed: 11/29/2022]
Abstract
RNA silencing is a common strategy shared by eukaryotic organisms to regulate gene expression, and also operates as a defense mechanism against invasive nucleic acids such as viral transcripts. The silencing pathway is quite sophisticated in higher eukaryotes but the distinct steps and nature of effector complexes vary between and even within species. To counteract this defense mechanism viruses have evolved the ability to encode proteins that suppress silencing to protect their genomes from degradation. This review focuses on our current understanding of how individual components of the plant RNA silencing mechanism are directed against viruses, and how in turn virus-encoded suppressors target one or more key events in the silencing cascade.
Collapse
Affiliation(s)
- Veria Alvarado
- Department of Plant Pathology and Microbiology, Texas A&M University, 2132 TAMU, College Station, TX 77843, United States
| | | |
Collapse
|
24
|
Castaño A, Ruiz L, Hernández C. Insights into the translational regulation of biologically active open reading frames of Pelargonium line pattern virus. Virology 2009; 386:417-26. [PMID: 19217134 DOI: 10.1016/j.virol.2009.01.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Revised: 12/13/2008] [Accepted: 01/15/2009] [Indexed: 10/21/2022]
Abstract
Pelargonium line pattern virus (PLPV), a proposed member of a prospective genus (Pelarspovirus) within family Tombusviridae, has a positive-sense, single-stranded genomic RNA. According to previous predictions, it contains six open reading frames (ORFs) potentially encoding proteins of 27 (p27), 13 (p13), 87 (p87), 7 (p7), 6 (p6), and 37 kDa (p37). Using a variety of techniques we demonstrate that all predicted ORFs are functional, with the exception of (p13) and (p6). We also characterize a previously unidentified ORF which encodes a 9.7 kDa protein (p9.7) that is essential for viral movement. Furthermore, we present evidence that the single subgenomic RNA (sgRNA) produced by the virus directs synthesis of p7, p9.7 and p37. Remarkably, the translation of these totally unrelated proteins is coordinated via leaky-scanning. This mechanism seems to be favoured by the poor translation context of the start codon of ORF(p7), the non-AUG weak initiation codon of ORF(p9.7) and the lack of additional AUG codons in any reading frame preceding ORF(p37). The results also suggest that precise regulation of protein production from the sgRNA is critical for virus viability. Altogether, the data supports the notion that PLPV belongs to a new genus of plant viruses.
Collapse
Affiliation(s)
- Aurora Castaño
- Instituto de Biología Molecular y Celular de Plantas (Consejo Superior de Investigaciones Científicas-UPV), Campus Universidad Politécnica de Valencia, Avenida de los Naranjos, 46022 Valencia, Spain
| | | | | |
Collapse
|
25
|
Li C, Zhang K, Zeng X, Jackson S, Zhou Y, Hong Y. A cis element within flowering locus T mRNA determines its mobility and facilitates trafficking of heterologous viral RNA. J Virol 2009; 83:3540-8. [PMID: 19193810 PMCID: PMC2663265 DOI: 10.1128/jvi.02346-08] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2008] [Accepted: 01/22/2009] [Indexed: 01/18/2023] Open
Abstract
The Arabidopsis flowering locus T (FT) gene encodes the mobile florigen essential for floral induction. While movement of the FT protein has been shown to occur within plants, systemic spread of FT mRNA remains to be unequivocally demonstrated. Utilizing novel RNA mobility assay vectors based on two distinct movement-defective viruses, Potato virus X and Turnip crinkle virus, and an agroinfiltration assay, we demonstrate that nontranslatable FT mRNA, independent of the FT protein, moves throughout Nicotiana benthamiana and mutant Arabidopsis plants and promotes systemic trafficking of viral and green fluorescence protein RNAs. Viral ectopic expression of FT induced flowering in the short-day N. tabacum Maryland Mammoth tobacco under long-day conditions. Recombinant Potato virus X bearing FT RNA spread and established systemic infection more quickly than the parental virus. The cis-acting element essential for RNA movement was mapped to the nucleotides 1 to 102 of the FT mRNA coding sequence. These data demonstrate that a plant self-mobile RNA molecule can mediate long-distance trafficking of heterologous RNAs and raise the possibility that FT RNA, along with the FT protein, may be involved in the spread of the floral stimulus throughout the plant.
Collapse
Affiliation(s)
- Chunyang Li
- Warwick HRI, University of Warwick, Wellesbourne, Warwick CV35 9EF, United Kingdom.
| | | | | | | | | | | |
Collapse
|
26
|
Shi Y, Ryabov EV, van Wezel R, Li C, Jin M, Wang W, Fan Z, Hong Y. Suppression of local RNA silencing is not sufficient to promote cell-to-cell movement of Turnip crinkle virus in Nicotiana benthamiana. PLANT SIGNALING & BEHAVIOR 2009; 4:15-22. [PMID: 19568335 PMCID: PMC2634062 DOI: 10.4161/psb.4.1.7573] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Accepted: 12/09/2008] [Indexed: 05/19/2023]
Abstract
The biological relationship between suppression of RNA silencing and virus movement poses an intriguing question in virus-plant interactions. Here, we have used a local RNA silencing assay, based on a movement-deficient Turnip crinkle virus TCV/GFPDeltaCP, to investigate the influence of silencing suppression by three different viral suppressors: the TCV 38K coat protein (CP), the 126K protein of Tobacco mosaic virus (TMV), and P19 of Tomato bushy stunt virus (TBSV) on cell-to-cell movement and long-distance spread of TCV/GFPDeltaCP. First, we found that TCV CP blocked the induction of local RNA silencing, but failed to support virus trafficking in silencing-suppressed transgenic plants, although it acted as a functional movement protein in non-transformed plants. Second, we demonstrated that the TMV 126K suppressor inhibited TCV/GFPDeltaCP-mediated RNA silencing, but did not facilitate intercellular spread of the chimaeric carmovirus. However, TMV and TMVDeltaCP prevented the initiation of RNA silencing by TCV/GFPDeltaCP and caused TCV/GFPDeltaCP to move between cells, although only TMV supported its long-distance spread. Third, TBSV P19 functioned as a movement protein for TCV/GFPDeltaCP and as a silencing suppressor in non-transformed and silencing-suppressed transgenic plants. We further identified three types of mutant P19 proteins that possessed no or varied functionality in silencing suppression and in the facilitation of carmovirus movement. These results suggest that, although suppression of local RNA silencing is essential for the maintenance of viral RNA, recovery of cell-to-cell movement and long-distance spread of movement-deficient carmoviruses is not a direct consequence of such silencing suppression.
Collapse
Affiliation(s)
- Yan Shi
- Warwick HRI; University of Warwick; Warwick, Wellesbourne UK
- Department of Plant Pathology and State Key Laboratory of Agrobiotechnology; China Agricultural University; Beijing China
| | - Eugene V Ryabov
- Warwick HRI; University of Warwick; Warwick, Wellesbourne UK
| | - Rene van Wezel
- Warwick HRI; University of Warwick; Warwick, Wellesbourne UK
| | - Chunyang Li
- Warwick HRI; University of Warwick; Warwick, Wellesbourne UK
| | - Mingfei Jin
- Warwick HRI; University of Warwick; Warwick, Wellesbourne UK
- School of Life Science; East China Normal University; Shanghai China
| | - Wenjing Wang
- Warwick HRI; University of Warwick; Warwick, Wellesbourne UK
| | - Zaifeng Fan
- Warwick HRI; University of Warwick; Warwick, Wellesbourne UK
- Department of Plant Pathology and State Key Laboratory of Agrobiotechnology; China Agricultural University; Beijing China
| | - Yiguo Hong
- Warwick HRI; University of Warwick; Warwick, Wellesbourne UK
| |
Collapse
|
27
|
Ohki T, Sako I, Kanda A, Mochizuki T, Honda Y, Tsuda S. A new strain of Melon necrotic spot virus that is unable to systemically infect Cucumis melo. PHYTOPATHOLOGY 2008; 98:1165-1170. [PMID: 18943404 DOI: 10.1094/phyto-98-11-1165] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We report a new strain of Melon necrotic spot virus (MNSV) that is unable to systemically infect Cucumis melo. A spherical virus (W-isolate), about 30 nm in diameter like a carmovirus, was isolated from watermelons with necrotic symptoms. The W-isolate had little serological similarity to MNSV, and it did not cause any symptoms in six melon cultivars susceptible to MNSV; however, the host range of the W-isolate was limited exclusively to cucurbitaceous plants, and transmission by O. bornovanus was confirmed. Its genomic structure was identical to that of MNSV, and its p89 protein and coat protein (CP) showed 81.6 to 83.2% and 74.1 to 75.1% identity to those of MNSV, respectively. Analysis of protoplast showed that the W-isolate replicated in melons at the single-cell level. Furthermore, chimeric clones carrying the CP of MNSV induced necrotic spots in melons. These results suggested that the absence of symptoms in melons was due to a lack of ability of the W-isolate to move from cell to cell. In view of these findings, we propose that the new isolate should be classified as a novel MNSV watermelon strain.
Collapse
Affiliation(s)
- Takehiro Ohki
- National Agricultural Research Center, Ibaraki, Japan.
| | | | | | | | | | | |
Collapse
|
28
|
Powers JG, Sit TL, Qu F, Morris TJ, Kim KH, Lommel SA. A versatile assay for the identification of RNA silencing suppressors based on complementation of viral movement. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2008; 21:879-90. [PMID: 18533829 DOI: 10.1094/mpmi-21-7-0879] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The cell-to-cell movement of Turnip crinkle virus (TCV) in Nicotiana benthamiana requires the presence of its coat protein (CP), a known suppressor of RNA silencing. RNA transcripts of a TCV construct containing a reporter gene (green fluorescent protein) (TCV-sGFP) in place of the CP open reading frame generated foci of three to five cells. TCV CP delivered in trans by Agrobacterium tumefaciens infiltration potentiated movement of TCV-sGFP and increased foci diameter, on average, by a factor of four. Deletion of the TCV movement proteins in TCV-sGFP (construct TCVDelta92-sGFP) abolished the movement complementation ability of TCV CP. Other known suppressors of RNA silencing from a wide spectrum of viruses also complemented the movement of TCV-sGFP when delivered in trans by Agrobacterium tumefaciens. These include suppressors from nonplant viruses with no known plant movement function, demonstrating that this assay is based solely on RNA silencing suppression. While the TCV-sGFP construct is primarily used as an infectious RNA transcript, it was also subcloned for direct expression from Agrobacterium tumefaciens for simple quantification of suppressor activity based on fluorescence levels in whole leaves. Thus, this system provides the flexibility to assay for suppressor activity in either the cytoplasm or nucleus, depending on the construct employed.
Collapse
Affiliation(s)
- Jason G Powers
- Department of Genetics, North Carolina State University, Box 7614, Raleigh, NC 27695-7614, U.S.A
| | | | | | | | | | | |
Collapse
|
29
|
Abstract
Reverse genetic approach is widely used in virology as it makes possible direct identification of viral gene function and uses RNA genomes as vectors. Production of infectious cDNA clones is an essential step in developing a reverse genetic system for an RNA virus. Here, we present rapid method for generation of infectious cDNA clone for Turnip crinkle virus (TCV). The infectious cDNA clone could be used for production of in vitro transcripts with the T7 RNA polymerase which could be used for infection of plants or plant cell protoplasts. The procedure described here includes purification of TCV, viral RNA extraction, reverse transcription, PCR amplification of the full-length cDNA copy of TCV linked to a T7 RNA polymerase promoter, cloning into a plasmid vector, in vitro transcription, and selection of infectious clones.
Collapse
|
30
|
Zhou Y, Ryabov E, Zhang X, Hong Y. Influence of viral genes on the cell-to-cell spread of RNA silencing. JOURNAL OF EXPERIMENTAL BOTANY 2008; 59:2803-13. [PMID: 18515824 PMCID: PMC2486475 DOI: 10.1093/jxb/ern141] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Revised: 04/21/2008] [Accepted: 04/22/2008] [Indexed: 05/19/2023]
Abstract
The turnip crinkle virus-based vector TCV-GFP Delta CP had been devised previously to study cell-to-cell and long-distance spread of virus-induced RNA silencing. TCV-GFP Delta CP, which had been constructed by replacing the coat protein (CP) gene with a green fluorescent protein (GFP) coding sequence, was able to induce RNA silencing in single epidermal cells, from which RNA silencing spread from cell-to-cell. Using this unique local silencing assay together with mutagenesis analysis, two TCV genes, p8 and p9, which were involved in the intercellular spread of virus-induced RNA silencing, were identified. TCV-GFP Delta CP and its p8- or p9-mutated derivatives, TCVmp8-GFP Delta CP and TCVmp9-GFP Delta CP, replicated efficiently but were restricted to single Nicotiana benthamiana epidermal cells. TCV-GFP Delta CP, TCVmp8-GFP Delta CP, or TCVmp9-GFP Delta CP was able to initiate RNA silencing that targeted and degraded recombinant viral RNAs in inoculated leaves of the GFP-expressing N. benthamiana line 16c. However, cell-to-cell spread of silencing to form silencing foci was triggered only by TCV-GFP Delta CP. Non-replicating TCVmp88-GFP Delta CP and TCVmp28mp88-GFP Delta CP with dysfunctional replicase genes, and single-stranded gfp RNA did not induce RNA silencing. Transient expression of the TCV p9 protein could effectively complement TCVmp9-GFP Delta CP to facilitate intercellular spread of silencing. These data suggest that the plant cellular trafficking machinery could hijack functional viral proteins to permit cell-to-cell movement of RNA silencing.
Collapse
Affiliation(s)
| | | | | | - Yiguo Hong
- Warwick HRI, University of Warwick, Wellesbourne, Warwick, CV35 9EF, UK
| |
Collapse
|
31
|
Andrade M, Sato M, Uyeda I. Two Resistance Modes to Clover yellow vein virus in Pea Characterized by a Green Fluorescent Protein-Tagged Virus. PHYTOPATHOLOGY 2007; 97:544-550. [PMID: 18943572 DOI: 10.1094/phyto-97-5-0544] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
ABSTRACT This study characterized resistance in pea lines PI 347295 and PI 378159 to Clover yellow vein virus (ClYVV). Genetic cross experiments showed that a single recessive gene controls resistance in both lines. Conventional mechanical inoculation did not result in infection; however, particle bombardment with infectious plasmid or mechanical inoculation with concentrated viral inocula did cause infection. When ClYVV No. 30 isolate was tagged with a green fluorescent protein (GFP) and used to monitor infection, viral cell-to-cell movement differed in the two pea lines. In PI 347595, ClYVV replicated at a single-cell level, but did not move to neighboring cells, indicating that resistance operated at a cell-to-cell step. In PI 378159, the virus moved to cells around the infection site and reached the leaf veins, but viral movement was slower than that in the susceptible line. The viruses observed around the infection sites and in the veins were then recovered and inoculated again by a conventional mechanical inoculation method onto PI 378159 demonstrating that ClYVV probably had mutated and newly emerged mutant viruses can move to neighboring cells and systemically infect the plants. Tagging the virus with GFP was an efficient tool for characterizing resistance modes. Implications of the two resistance modes are discussed.
Collapse
|
32
|
Navarro JA, Genovés A, Climent J, Saurí A, Martínez-Gil L, Mingarro I, Pallás V. RNA-binding properties and membrane insertion of Melon necrotic spot virus (MNSV) double gene block movement proteins. Virology 2006; 356:57-67. [PMID: 16950492 DOI: 10.1016/j.virol.2006.07.040] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Revised: 05/01/2006] [Accepted: 07/06/2006] [Indexed: 11/22/2022]
Abstract
Advances in structural and biochemical properties of carmovirus movement proteins (MPs) have only been obtained in p7 and p9 from Carnation mottle virus (CarMV). Alignment of carmovirus MPs revealed a low conservation of amino acid identity but interestingly, similarity was elevated in regions associated with the functional secondary structure elements reported for CarMV which were conserved in all studied proteins. Nevertheless, some differential features in relation with CarMV MPs were identified in those from Melon necrotic virus (MNSV) (p7A and p7B). p7A was a soluble non-sequence specific RNA-binding protein, but unlike CarMV p7, its central region alone could not account for the RNA-binding properties of the entire protein. In fact, a 22-amino acid synthetic peptide whose sequence corresponds to this central region rendered an apparent dissociation constant (K(d)) significantly higher than that of the corresponding entire protein (9 mM vs. 0.83-25.7 microM). This p7A-derived peptide could be induced to fold into an alpha-helical structure as demonstrated for other carmovirus p7-like proteins. Additionally, in vitro fractionation of p7B transcription/translation mixtures in the presence of ER-derived microsomal membranes strongly suggested that p7B is an integral membrane protein. Both characteristics of these two small MPs forming the double gene block (DGB) of MNSV are discussed in the context of the intra- and intercellular movement of carmovirus.
Collapse
Affiliation(s)
- J A Navarro
- Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia-CSIC, Avenida de los Naranjos s/n, 46022 Valencia, Spain
| | | | | | | | | | | | | |
Collapse
|
33
|
Yuan X, Cao Y, Xi D, Guo L, Han C, Li D, Zhai Y, Yu J. Analysis of the subgenomic RNAs and the small open reading frames of Beet black scorch virus. J Gen Virol 2006; 87:3077-3086. [PMID: 16963767 DOI: 10.1099/vir.0.81928-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A full-length cDNA of the genome of Beet black scorch virus (BBSV), isolate Ningxia, was constructed and modified by site-directed mutagenesis to permit in vitro transcription of mutant viral RNAs. Two subgenomic (sg) RNAs (sgRNA1 and sgRNA2) appeared during BBSV replication. Mutagenesis revealed that sgRNA1 transcription was initiated at G2209 within the P82 polymerase subunit open reading frame (ORF) and that transcription of sgRNA2 began at G2526 within the nested p7b/p5' ORF. Initiation-codon shifting or premature termination of translation of the three ORFs (P7a, P7b and P5') encoded by sgRNA1 indicated that each of the genes was required for localized movement, accumulation of viral RNAs and formation of local lesions on the leaves of Chenopodium amaranticolor. Microscopic observations of the distribution of green fluorescent protein fused to the N-terminal portion of the capsid protein provided additional evidence that the P7a, P7b and P5' proteins are each required for cell-to-cell movement. In contrast, elimination of sgRNA2 showed that the BBSV coat protein was not required for viral RNA accumulation or the appearance of local lesions on C. amaranticolor. In addition, disruption of the small P5 ORF previously predicted by computer analysis to originate at the C terminus of the P82 ORF had no effect on disease phenotype, suggesting that this ORF may represent a cryptic, non-essential gene. These results show that BBSV has a novel cell-to-cell movement protein organization that differs in size and sequence from that of other viruses.
Collapse
Affiliation(s)
- Xuefeng Yuan
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100094, PR China
| | - Yunhe Cao
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100094, PR China
| | - Dehui Xi
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100094, PR China
| | - Lihua Guo
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100094, PR China
| | - Chenggui Han
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100094, PR China
| | - Dawei Li
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100094, PR China
| | - Yafeng Zhai
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100094, PR China
| | - Jialin Yu
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100094, PR China
| |
Collapse
|
34
|
Genovés A, Navarro JA, Pallás V. Functional analysis of the five melon necrotic spot virus genome-encoded proteins. J Gen Virol 2006; 87:2371-2380. [PMID: 16847133 DOI: 10.1099/vir.0.81793-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Function of the melon necrotic spot virus (MNSV) genome-encoded proteins (p29, p89, p7A, p7B and p42) has been studied. Protein-expression mutants of an infectious, full-length cDNA clone of a Spanish MNSV-Al isolate and a recombinant green fluorescent protein (GFP)-expressing virus were used in infection bioassays on melon plants. Results revealed that p29 and p89 are both essential for virus replication, whereas small proteins p7A and p7B are sufficient to support viral movement between adjacent cells operating in trans. It is also demonstrated that, in addition to its structural role as coat protein, p42 is an important factor controlling symptoms and is required for systemic transport. Moreover, both p42 and p7B, among all of the MNSV-encoded proteins, were able to delay RNA silencing in transient-expression assays on GFP-transgenic Nicotiana benthamiana plants. Finally, the presence of p42 also produced an enhancing effect on local spread similar to that of potyviral helper component proteinase (HC-Pro), probably due to its RNA silencing-suppression ability.
Collapse
Affiliation(s)
- A Genovés
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), UPV-CSIC, Avda de los Naranjos s/n, 46022 Valencia, Spain
| | - J A Navarro
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), UPV-CSIC, Avda de los Naranjos s/n, 46022 Valencia, Spain
| | - V Pallás
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), UPV-CSIC, Avda de los Naranjos s/n, 46022 Valencia, Spain
| |
Collapse
|
35
|
Deleris A, Gallego-Bartolome J, Bao J, Kasschau KD, Carrington JC, Voinnet O. Hierarchical Action and Inhibition of Plant Dicer-Like Proteins in Antiviral Defense. Science 2006; 313:68-71. [PMID: 16741077 DOI: 10.1126/science.1128214] [Citation(s) in RCA: 629] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The mechanisms underlying induction and suppression of RNA silencing in the ongoing plant-virus arms race are poorly understood. We show here that virus-derived small RNAs produced by Arabidopsis Dicer-like 4 (DCL4) program an effector complex conferring antiviral immunity. Inhibition of DCL4 by a viral-encoded suppressor revealed the subordinate antiviral activity of DCL2. Accordingly, inactivating both DCL2 and DCL4 was necessary and sufficient to restore systemic infection of a suppressor-deficient virus. The effects of DCL2 were overcome by increasing viral dosage in inoculated leaves, but this could not surmount additional, non-cell autonomous effects of DCL4 specifically preventing viral unloading from the vasculature. These findings define a molecular framework for studying antiviral silencing and defense in plants.
Collapse
Affiliation(s)
- Angélique Deleris
- Institut de Biologie Moléculaire des Plantes, CNRS Unité Propre de Recherche (UPR) 2357, 12, rue du Général Zimmer, 67084 Strasbourg Cedex, France
| | | | | | | | | | | |
Collapse
|
36
|
Ion-Nagy L, Lansac M, Eyquard JP, Salvador B, Garcia JA, Le Gall O, Hernould M, Schurdi-Levraud V, Decroocq V. PPV long-distance movement is occasionally permitted in resistant apricot hosts. Virus Res 2006; 120:70-8. [PMID: 16504333 DOI: 10.1016/j.virusres.2006.01.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2005] [Revised: 01/19/2006] [Accepted: 01/22/2006] [Indexed: 10/25/2022]
Abstract
The interactions between Plum pox virus (PPV), a member of the Potyvirus genus, and Prunus host plants are, up to now, poorly understood. In the current paper, fluorescence stereomicroscopy, in situ hybridisation and immunogold detection were performed in order to evaluate the virus transport and cellular distribution. The behavior of PPV in several susceptible (cv. "Moniqui" and "Screara") and resistant apricot genotypes (cv. "Harlayne", "Henderson", "Harcot", "Goldrich", "Stella" and "Stark Early Orange") were compared. Viral RNA was detected by in situ hybridisation in stem tissues close to the inoculation point, irrespective of the resistance status of the variety. Systemic infection was evidenced by virus immunodetection and by fluorescence detection of a GFP-tagged PPV in distant leaf sections. The signal obtained by in situ hybridisation colocalised with the fluorescence produced by GFP-tagged PPV in the same plant material but did not colocalise with the signal obtained by immunostaining. Intensity of the PPV infection in susceptible apricot cultivars varied depending on genotypes. The behavior of PPV in systemic leaves was clearly distinct between susceptible and resistant cultivars. While PPV was spreading widely around the major and minor veins in susceptible leaves, in the resistant apricot genotypes it was restricted to isolated spots consisting of few cells embedded in the mesophyll tissue. In summary, differences in the ability of PPV to systemically infect susceptible and resistant apricot cultivars were evident but nevertheless, long-distance transport of PPV occured in resistant apricot scions.
Collapse
Affiliation(s)
- Ligia Ion-Nagy
- Unité Mixte de Recherches INRA-Université Bordeaux 2 Génomique et Développement du Pouvoir Pathogène, IBVM, BP 81, F-33883 Villenave d'Ornon, France
| | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Qu F, Ye X, Hou G, Sato S, Clemente TE, Morris TJ. RDR6 has a broad-spectrum but temperature-dependent antiviral defense role in Nicotiana benthamiana. J Virol 2005; 79:15209-17. [PMID: 16306592 PMCID: PMC1316014 DOI: 10.1128/jvi.79.24.15209-15217.2005] [Citation(s) in RCA: 188] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2005] [Accepted: 09/27/2005] [Indexed: 11/20/2022] Open
Abstract
SDE1/SGS2/RDR6, a putative RNA-dependent RNA polymerase (RdRP) from Arabidopsis thaliana, has previously been found to be indispensable for maintaining the posttranscriptional silencing of transgenes, but it is seemingly redundant for antiviral defense. To elucidate the antiviral role of this RdRP in a different host plant and to evaluate whether plant growth conditions affect its role, we down-regulated expression of the Nicotiana benthamiana homolog, NbRDR6, and examined the plants for altered susceptibility to various viruses at different growth temperatures. The results we describe here clearly show that plants with reduced expression of NbRDR6 were more susceptible to all viruses tested and that this effect was more pronounced at higher growth temperatures. Diminished expression of NbRDR6 also permitted efficient multiplication of tobacco mosaic virus in the shoot apices, leading to serious disruption with microRNA-mediated developmental regulation. Based on these results, we propose that NbRDR6 participates in the antiviral RNA silencing pathway that is stimulated by rising temperatures but suppressed by virus-encoded silencing suppressors. The relative strengths of these two factors, along with other plant defense components, critically influence the outcome of virus infections.
Collapse
Affiliation(s)
- Feng Qu
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588-0666, USA
| | | | | | | | | | | |
Collapse
|
38
|
Lansac M, Eyquard JP, Salvador B, Garcia JA, Le Gall O, Decroocq V, Schurdi-Levraud Escalettes V. Application of GFP-tagged Plum pox virus to study Prunus-PPV interactions at the whole plant and cellular levels. J Virol Methods 2005; 129:125-33. [PMID: 15993953 DOI: 10.1016/j.jviromet.2005.05.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2005] [Revised: 05/10/2005] [Accepted: 05/16/2005] [Indexed: 11/15/2022]
Abstract
The Sharka disease caused by the potyvirus Plum pox virus (PPV) is one of the most serious viral diseases affecting stone fruit trees. The study of PPV/Prunus interaction under greenhouse controlled conditions is space, time, labor consuming. While the PPV/Prunus interactions are now quite well known at the whole plant level, few data however are available on the interactions between the virus and the Prunus host plants at the cellular level. Using a green fluorescent protein (GFP)-tagged M type PPV strain, combined to an in vitro inoculation procedure, we developed a novel tool to track PPV invasion in Prunus persica (peach) cv. GF305 and Prunus armeniaca (apricot) cv. Screara susceptible hosts. Different graft combinations were performed using in vitro-maintained healthy or GFP-tagged PPV infected 'GF305' and 'Screara'. Contact for 30 days in grafts between the inoculum and the genotype to be tested were found sufficient to allow the systemic spread of the recombinant virus: fluorescence from GFP-tagged PPV could easily be detected in the entire plant under a binocular microscope allowing quick and reliable sorting of infected plants. Using a fluorescence stereomicroscopy or confocal microscopy, GFP could also be observed in stem cross-sections especially in epidermis and pith cells. In vitro grafting inoculation with GFP-tagged PPV provides a new and powerful tool to facilitate mid-term virus maintenance. Moreover, this tool will be of special importance in the study of PPV infection dynamics in Prunus, allowing as well precise observations of cellular events related to PPV/Prunus interactions.
Collapse
Affiliation(s)
- M Lansac
- INRA Centre de Bordeaux, Virologie, IBVM, UMR GDPP INRA/UB2, IBVM, Villenave d'Ornon, France
| | | | | | | | | | | | | |
Collapse
|
39
|
Ryabov EV, van Wezel R, Walsh J, Hong Y. Cell-to-Cell, but not long-distance, spread of RNA silencing that is induced in individual epidermal cells. J Virol 2004; 78:3149-54. [PMID: 14990735 PMCID: PMC353744 DOI: 10.1128/jvi.78.6.3149-3154.2004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2003] [Accepted: 11/17/2003] [Indexed: 11/20/2022] Open
Abstract
A Turnip crinkle virus (TCV)-based system was devised to discriminate cell-to-cell and systemic long-distance spread of RNA silencing in plants. Modified TCV-GFPDeltaCP, constructed by replacing the coat protein (CP) gene with the green fluorescent protein (GFP) gene, replicated in single epidermal cells but failed to move from cell to cell in Nicotiana benthamiana. Mechanical inoculation of TCV-GFPDeltaCP induced effective RNA silencing in single epidermal cells which spread from cell to cell to form silenced foci on inoculated leaves, but no long-distance systemic spread of RNA silencing occurred. Agroinfiltration of TCV-GFPDeltaCP was, however, able to induce both local and systemic RNA silencing. TCV coinfection arrested TCV-GFPDeltaCP-mediated local induction of RNA silencing. Possible mechanisms involved in cell-to-cell and long-distance spread of RNA silencing are discussed.
Collapse
Affiliation(s)
- Eugene V Ryabov
- Horticulture Research International, East Malling, West Malling, Kent ME19 6BJ, United Kingdom.
| | | | | | | |
Collapse
|
40
|
Zhang F, Simon AE. A novel procedure for the localization of viral RNAs in protoplasts and whole plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2003; 35:665-673. [PMID: 12940959 DOI: 10.1046/j.1365-313x.2003.01837.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Analysis of virus spread using co-expressed reporter proteins has provided important details on cell-to-cell and long-distance movement of viruses in plants. However, most viruses cannot tolerate insertion of large non-viral segments or loss of any open-reading frames, procedures required to detect viruses non-evasively. A technique used to localize mRNAs intracellularly in yeast has been modified for detection of viral RNAs in whole plants. The technique makes use of the binding of the coat protein of MS2 bacteriophage (CPMS2) to a 19 base hairpin (hp). A fusion protein, consisting of the CPMS2, green fluorescent protein (GFP), and a nuclear localization signal (NLS), was nuclear-localized upon transient expression in protoplasts. However, addition of the hp to the 3' untranslated region of Turnip crinkle virus (TCV-hp) and co-transfection of the virus and fusion protein construct into protoplasts resulted in the re-location of GFP to the cytoplasm. Neither the insertion of the hp nor the interaction with the fusion protein impaired any viral functions. Transgenic plants expressing the GFP-NLS-CPMS2 fusion protein were generated, and GFP was detected in nuclei of young plant cells. Foci of GFP cytoplasmic fluorescence were detected in TCV-hp-inoculated leaves at 2 days post-inoculation. Later, GFP was detected in young leaves near the midvein and in the base (support) cells of trichomes in the vicinity of secondary and tertiary veins. In older leaves, cytoplasmic GFP could be visualized throughout many of the leaves. This technique should be amenable for detection of any virus with a transformable plant (or animal) host and may also prove useful for localizing properly engineered host RNAs.
Collapse
Affiliation(s)
- Fengli Zhang
- Department of Cell Biology and Molecular Genetics, University of Maryland College Park, College Park, MD 20742, USA
| | | |
Collapse
|
41
|
Porta C, Lomonossoff GP. Viruses as vectors for the expression of foreign sequences in plants. Biotechnol Genet Eng Rev 2003; 19:245-91. [PMID: 12520880 DOI: 10.1080/02648725.2002.10648031] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Claudine Porta
- Horticulture Research International Wellesbourne, Warwick CV35 9EF, UK.
| | | |
Collapse
|
42
|
Scholthof KBG, Mirkov TE, Scholthof HB. Plant virus gene vectors: biotechnology applications in agriculture and medicine. GENETIC ENGINEERING 2003; 24:67-85. [PMID: 12416301 DOI: 10.1007/978-1-4615-0721-5_4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
Affiliation(s)
- Karen-Beth G Scholthof
- Department of Plant Pathology and Microbiology, Texas A&M University, 2132 TAMU, College Station, TX 77843, USA
| | | | | |
Collapse
|
43
|
Thomas CL, Leh V, Lederer C, Maule AJ. Turnip crinkle virus coat protein mediates suppression of RNA silencing in Nicotiana benthamiana. Virology 2003; 306:33-41. [PMID: 12620795 DOI: 10.1016/s0042-6822(02)00018-1] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
All of the protein products of Turnip crinkle virus (TCV; Tombusviridae, Carmovirus) were tested for their ability to suppress RNA silencing of a reporter gene after transient expression in Agrobacterium-infiltrated Nicotiana benthamiana leaves. Only the capsid protein, P38, showed suppression activity, although this was not obvious when P38 was expressed as part of a TCV infection of the same tissues. When P38 was expressed from a PVX vector, symptoms with enhanced severity that correlated with increased PVX RNA accumulation were observed. This contradiction between ectopic expression of P38 and TCV infection could be accounted for if the active determinant of suppressor activity within P38 was sequestered within the capsid protein structure. The N-terminal 25 amino acids were shown to be important for this activity. This region forms part of the unexposed R-domain that interacts with the RNA within the virus particle. This observation throws light on some of the complex biology exhibited by TCV.
Collapse
Affiliation(s)
- Carole L Thomas
- John Innes Centre, Norwich Research Park, NR4 7UH, Colney, Norwich, UK
| | | | | | | |
Collapse
|
44
|
Qu F, Morris TJ. Efficient infection of Nicotiana benthamiana by Tomato bushy stunt virus is facilitated by the coat protein and maintained by p19 through suppression of gene silencing. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2002; 15:193-202. [PMID: 11952121 DOI: 10.1094/mpmi.2002.15.3.193] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Tomato bushy stunt virus (TBSV) is one of few RNA plant viruses capable of moving systemically in some hosts in the absence of coat protein (CP). TBSV also encodes another protein (p19) that is not required for systemic movement but functions as a symptom determinant in Nicotiana benthamiana. Here, the role of both CP and p19 in the systemic spread has been reevaluated by utilizing transgenic N. benthamiana plants expressing the movement protein (MP) of Red clover necrotic mosaic virus and chimeric TBSV mutants that express CP of Turnip crinkle virus. Through careful examination of the infection phenotype of a series of mutants with changes in the CP and p19 genes, we demonstrate that both of these genes are required for efficient systemic invasion of TBSV in N. benthamiana. The CP likely enables efficient viral unloading from the vascular system in the form of assembled virions, whereas p19 enhances systemic infection by suppressing the virus-induced gene silencing.
Collapse
Affiliation(s)
- Feng Qu
- School of Biological Sciences, University of Nebraska-Lincoln, 68588-0118, USA
| | | |
Collapse
|
45
|
Chaerle L, Van Der Straeten D. Seeing is believing: imaging techniques to monitor plant health. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1519:153-66. [PMID: 11418181 DOI: 10.1016/s0167-4781(01)00238-x] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Historically, early stress-induced changes in plants have been mainly detected after destructive sampling followed by biochemical and molecular determinations. Imaging techniques that allow immediate detection of stress-situations, before visual symptoms appear and adverse effects become established, are emerging as promising tools for crop yield management. Such monitoring approaches can also be applied to screen plant populations for mutants with increased stress tolerance. At the laboratory scale, different imaging methods can be tested and one or a combination best suited for crop surveillance chosen. The system of choice can be applied under controlled laboratory conditions to guide selective sampling for the molecular characterisation of rapid stress-induced changes. Such an approach permits to isolate presymptomatically induced genes, or to obtain a panoramic view of early gene expression using gene-arrays when plants undergo physiological changes undetected by the human eye. Using this knowledge, plants can be engineered to be more stress resistant, and tested for field performance by the same methodologies. In ongoing efforts of genome characterisation, genes of unknown function are revealed at an ever-accelerating pace. By monitoring changes in phenotypic characteristics of transgenic plants expressing those genes, imaging techniques could help to identify their function.
Collapse
Affiliation(s)
- L Chaerle
- Department of Molecular Genetics, Ghent University, K.L. Ledeganckstraat 35, B-9000, Ghent, Belgium
| | | |
Collapse
|
46
|
Akgoz M, Nguyen QN, Talmadge AE, Drainville KE, Wobbe KK. Mutational analysis of Turnip crinkle virus movement protein p8. MOLECULAR PLANT PATHOLOGY 2001; 2:37-48. [PMID: 20572990 DOI: 10.1046/j.1364-3703.2001.00048.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Summary Turnip crinkle virus encodes two proteins, p8 and p9, that are both required for cell-to-cell movement. The p8 movement protein has been demonstrated to bind RNA in a cooperative manner, although, similar to many other plant virus movement proteins, it contains no canonical RNA binding domain(s). However, three positively charged regions of p8 may potentially form ionic interactions with the RNA backbone. To identify functional regions of p8, a series of alanine and deletion scanning mutations were produced. The effects of these mutations were analysed using both in vitro RNA binding assays and in vivo infections of susceptible (Di-3) and resistant (Di-17) Arabidopsis thaliana plants. Several mutants that have reduced RNA binding ability were also demonstrated to be movement deficient and replication competent. Based on these results, there appear to be two regions, located between amino acids 18 and 31, and 50 and 72, that are required for RNA binding. Furthermore, additional regions (amino acids 12-15, and 34-37) appear to play a role in vivo unrelated to in vitro RNA binding activity.
Collapse
Affiliation(s)
- M Akgoz
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd, Worcester, MA 01609, USA
| | | | | | | | | |
Collapse
|
47
|
Callaway A, Giesman-Cookmeyer D, Gillock ET, Sit TL, Lommel SA. The multifunctional capsid proteins of plant RNA viruses. ANNUAL REVIEW OF PHYTOPATHOLOGY 2001; 39:419-460. [PMID: 11701872 DOI: 10.1146/annurev.phyto.39.1.419] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This article summarizes studies of viral coat (capsid) proteins (CPs) of RNA plant viruses. In addition, we discuss and seek to interpret the knowledge accumulated to data. CPs are named for their primary function; to encapsidate viral genomic nucleic acids. However, encapsidation is only one feature of an extremely diverse array of structural, functional, and ecological roles played during viral infection and spread. Herein, we consider the evolution of viral CPs and their multitude of interactions with factors encoded by the virus, host plant, or viral vector (biological transmission agent) that influence the infection and epidemiological facets of plant disease. In addition, applications of today's understanding of CPs in the protection of crops from viral infection and use in the manufacture of valuable compounds are considered.
Collapse
Affiliation(s)
- A Callaway
- Department of Plant Pathology, North Carolina State University, Box 7616, Raleigh, North Carolina 27695-7616, USA.
| | | | | | | | | |
Collapse
|
48
|
Cohen Y, Qu F, Gisel A, Morris TJ, Zambryski PC. Nuclear localization of turnip crinkle virus movement protein p8. Virology 2000; 273:276-85. [PMID: 10915598 DOI: 10.1006/viro.2000.0440] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Turnip crinkle virus (TCV) is a single-stranded positive-sense RNA virus of the Carmovirus genus. Two of its five open reading frames (ORFs), encoding proteins of 8 and 9 kDa, are required for cell-to-cell movement of the virus. These movement proteins (MPs) were fused to green fluorescent protein (GFP) to determine their cellular localization. In protoplasts, p9-GFP, like GFP itself, is found throughout the cytoplasm, as well as in cell nuclei. In contrast, p8-GFP was confined to the cell nucleus. Similar localization patterns were observed when specific small peptide epitopes were fused to p8 and p9 proteins instead of GFP. The cytoplasmic localization of p9-GFP and nuclear localization of p8-GFP were also detected in leaves after particle bombardment of DNA encoding these fusion proteins or after overexpression of p8-GFP in transgenic Arabidopsis seedlings. The expression of the GFP fusion proteins by recombinant TCV viruses in infected protoplasts or on inoculated Arabidopsis leaves produced similar patterns. Unlike TMV-MP and other MPs studied to date, no obvious punctuate expression in the cell wall or association with the cytoskeleton was detected. The sequence analysis of p8 revealed two unique nuclear localization signals (NLSs), which were not conserved within p8 homologues of other viruses in the genus Carmovirus. Mutation in either of these NLSs did not disrupt the nuclear localization of p8-GFP. However, when both NLSs were mutated, p8-GFP expression was no longer restricted to cell nuclei. The NLSs are not required for cell-to-cell movement; TCV recombinant viruses mutated in one or both NLSs could still facilitate cell-to-cell movement of the virus. The nuclear localization of p8 suggests a novel function for this protein in the cell nucleus.
Collapse
Affiliation(s)
- Y Cohen
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California 94720, USA
| | | | | | | | | |
Collapse
|