1
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Akinyuwa MF, Price BK, Kang SH. Characterization of the proteins encoded by a recently emerged cotton-infecting Polerovirus. Virus Genes 2024:10.1007/s11262-024-02086-3. [PMID: 38907176 DOI: 10.1007/s11262-024-02086-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Accepted: 06/06/2024] [Indexed: 06/23/2024]
Abstract
The cotton leafroll dwarf virus (CLDV), an important viral pathogen responsible for substantial losses in cotton crops, has recently emerged in the United States (US). Although CLDV shares similarities with other members of the genus Polerovirus in terms of encoded proteins, their functional characteristics remain largely unexplored. In this study, we expressed and analyzed each protein encoded by CLDV to determine its intracellular localization using fluorescence protein fusion. We also evaluated their potential to induce plant responses, such as the induction of hypersensitive response-like necrosis and the generation of reactive oxygen species. Our findings show that the proteins encoded by CLDV exhibit comparable localization patterns and elicit similar robust plant responses as observed with cognate proteins from other viruses within the genus Polerovirus. This study contributes to our understanding of the functional repertoire of genes carried by Polerovirus members, particularly to CLDV that has recently emerged as a widespread viral pathogen infecting cotton in the US.
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Affiliation(s)
- Mary F Akinyuwa
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, 36849, USA
- Corteva Agriscience, Indianapolis, IN, 46268, USA
| | - Bailee K Price
- College of Sciences and Mathematics, Auburn University, Auburn, AL, 36849, USA
- Whiddon College of Medicine, University of South Alabama, Mobile, AL, 36688, USA
| | - Sung-Hwan Kang
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, 36849, USA.
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2
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Kim MH, Choi B, Jang SY, Choi JS, Kim S, Lee Y, Park S, Kwon SJ, Kang JH, Seo JK. The VP53 protein encoded by RNA2 of a fabavirus, broad bean wilt virus 2, is essential for viral systemic infection. Commun Biol 2024; 7:462. [PMID: 38627534 PMCID: PMC11021446 DOI: 10.1038/s42003-024-06170-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 04/09/2024] [Indexed: 04/19/2024] Open
Abstract
Plant viruses evolves diverse strategies to overcome the limitations of their genomic capacity and express multiple proteins, despite the constraints imposed by the host translation system. Broad bean wilt virus 2 (BBWV2) is a widespread viral pathogen, causing severe damage to economically important crops. It is hypothesized that BBWV2 RNA2 possesses two alternative in-frame translation initiation codons, resulting in the production of two largely overlapping proteins, VP53 and VP37. In this study, we aim to investigate the expression and function of VP53, an N-terminally 128-amino-acid-extended form of the viral movement protein VP37, during BBWV2 infection. By engineering various recombinant and mutant constructs of BBWV2 RNA2, here we demonstrate that VP53 is indeed expressed during BBWV2 infection. We also provide evidence of the translation of the two overlapping proteins through ribosomal leaky scanning. Furthermore, our study highlights the indispensability of VP53 for successful systemic infection of BBWV2, as its removal results in the loss of virus infectivity. These insights into the translation mechanism and functional role of VP53 during BBWV2 infection significantly contribute to our understanding of the infection mechanisms employed by fabaviruses.
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Affiliation(s)
- Myung-Hwi Kim
- Department of Agricultural Biotechnology, Seoul National University, Seoul, 08826, Republic of Korea
| | - Boram Choi
- Institutes of Green Bio Science and Technology, Seoul National University, Pyeongchang, 25354, Republic of Korea
| | - Seok-Yeong Jang
- Department of International Agricultural Technology, Seoul National University, Pyeongchang, 25354, Republic of Korea
| | - Ji-Soo Choi
- Department of International Agricultural Technology, Seoul National University, Pyeongchang, 25354, Republic of Korea
| | - Sora Kim
- Department of International Agricultural Technology, Seoul National University, Pyeongchang, 25354, Republic of Korea
| | - Yubin Lee
- Department of International Agricultural Technology, Seoul National University, Pyeongchang, 25354, Republic of Korea
| | - Suejin Park
- Department of Horticulture, Jeonbuk National University, Jeonju, 54896, Republic of Korea
| | - Sun-Jung Kwon
- Institutes of Green Bio Science and Technology, Seoul National University, Pyeongchang, 25354, Republic of Korea
| | - Jin-Ho Kang
- 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
| | - Jang-Kyun Seo
- Department of Agricultural Biotechnology, Seoul National University, Seoul, 08826, Republic of Korea.
- 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.
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3
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Carvalho CP, Han J, Khemsom K, Ren R, Camargo LEA, Miyashita S, Qu F. Single-cell mutation rate of turnip crinkle virus (-)-strand replication intermediates. PLoS Pathog 2023; 19:e1011395. [PMID: 37578959 PMCID: PMC10449226 DOI: 10.1371/journal.ppat.1011395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 08/24/2023] [Accepted: 07/25/2023] [Indexed: 08/16/2023] Open
Abstract
Viruses with single-stranded, positive-sense (+) RNA genomes incur high numbers of errors during replication, thereby creating diversified genome populations from which new, better adapted viral variants can emerge. However, a definitive error rate is known for a relatively few (+) RNA plant viruses, due to challenges to account for perturbations caused by natural selection and/or experimental set-ups. To address these challenges, we developed a new approach that exclusively profiled errors in the (-)-strand replication intermediates of turnip crinkle virus (TCV), in singly infected cells. A series of controls and safeguards were devised to ensure errors inherent to the experimental process were accounted for. This approach permitted the estimation of a TCV error rate of 8.47 X 10-5 substitution per nucleotide site per cell infection. Importantly, the characteristic error distribution pattern among the 50 copies of 2,363-base-pair cDNA fragments predicted that nearly all TCV (-) strands were products of one replication cycle per cell. Furthermore, some of the errors probably elevated error frequencies by lowering the fidelity of TCV RNA-dependent RNA polymerase, and/or permitting occasional re-replication of progeny genomes. In summary, by profiling errors in TCV (-)-strand intermediates incurred during replication in single cells, this study provided strong support for a stamping machine mode of replication employed by a (+) RNA virus.
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Affiliation(s)
- Camila Perdoncini Carvalho
- Department of Plant Pathology, The Ohio State University, Wooster, Ohio, United States of America
- Department of Plant Pathology and Nematology, Luiz de Queiroz College of Agriculture, University of Sao Paolo, Piracicaba, Brazil
| | - Junping Han
- Department of Plant Pathology, The Ohio State University, Wooster, Ohio, United States of America
| | - Khwannarin Khemsom
- Department of Plant Pathology, The Ohio State University, Wooster, Ohio, United States of America
| | - Ruifan Ren
- Department of Plant Pathology, The Ohio State University, Wooster, Ohio, United States of America
- Longping Branch, College of Biology, Hunan University, Changsha, China
| | - Luis Eduardo Aranha Camargo
- Department of Plant Pathology and Nematology, Luiz de Queiroz College of Agriculture, University of Sao Paolo, Piracicaba, Brazil
| | - Shuhei Miyashita
- Graduate School of Agricultural Science, Tohoku University, Tohoku, Japan
| | - Feng Qu
- Department of Plant Pathology, The Ohio State University, Wooster, Ohio, United States of America
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4
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Ren R, Zheng L, Han J, Perdoncini Carvalho C, Miyashita S, Zhang D, Qu F. Intracellular bottlenecking permits no more than three tomato yellow leaf curl virus genomes to initiate replication in a single cell. PLoS Pathog 2023; 19:e1011365. [PMID: 37126519 PMCID: PMC10174518 DOI: 10.1371/journal.ppat.1011365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 05/11/2023] [Accepted: 04/17/2023] [Indexed: 05/02/2023] Open
Abstract
Viruses are constantly subject to natural selection to enrich beneficial mutations and weed out deleterious ones. However, it remains unresolved as to how the phenotypic gains or losses brought about by these mutations cause the viral genomes carrying the very mutations to become more or less numerous. Previous investigations by us and others suggest that viruses with plus strand (+) RNA genomes may compel such selection by bottlenecking the replicating genome copies in each cell to low single digits. Nevertheless, it is unclear if similarly stringent reproductive bottlenecks also occur in cells invaded by DNA viruses. Here we investigated whether tomato yellow leaf curl virus (TYLCV), a small virus with a single-stranded DNA genome, underwent population bottlenecking in cells of its host plants. We engineered a TYLCV genome to produce two replicons that express green fluorescent protein and mCherry, respectively, in a replication-dependent manner. We found that among the cells entered by both replicons, less than 65% replicated both, whereas at least 35% replicated either of them alone. Further probability computation concluded that replication in an average cell was unlikely to have been initiated with more than three replicon genome copies. Furthermore, sequential inoculations unveiled strong mutual exclusions of these two replicons at the intracellular level. In conclusion, the intracellular population of the small DNA virus TYLCV is actively bottlenecked, and such bottlenecking may be a virus-encoded, evolutionarily conserved trait that assures timely selection of new mutations emerging through error-prone replication.
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Affiliation(s)
- Ruifan Ren
- Longping Branch, College of Biology, Hunan University, Changsha, China
- Department of Plant Pathology, The Ohio State University, Wooster, Ohio, United States of America
- Hunan Plant Protection Institute, Changsha, China
| | - Limin Zheng
- Department of Plant Pathology, The Ohio State University, Wooster, Ohio, United States of America
| | - Junping Han
- Department of Plant Pathology, The Ohio State University, Wooster, Ohio, United States of America
| | | | - Shuhei Miyashita
- Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Deyong Zhang
- Longping Branch, College of Biology, Hunan University, Changsha, China
- Hunan Plant Protection Institute, Changsha, China
| | - Feng Qu
- Department of Plant Pathology, The Ohio State University, Wooster, Ohio, United States of America
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5
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Zaulda FA, Yang SH, Han J, Mlotshwa S, Dorrance A, Qu F. A cowpea severe mosaic virus-based vector simplifies virus-induced gene silencing and foreign protein expression in soybean. PLANT METHODS 2022; 18:116. [PMID: 36307846 PMCID: PMC9617382 DOI: 10.1186/s13007-022-00950-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 09/04/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND Soybean gene functions cannot be easily interrogated through transgenic disruption (knock-out) of genes-of-interest, or transgenic overexpression of proteins-of-interest, because soybean transformation is time-consuming and technically challenging. An attractive alternative is to administer transient gene silencing or overexpression with a plant virus-based vector. However, existing virus-induced gene silencing (VIGS) and/or overexpression vectors suitable for soybean have various drawbacks that hinder their widespread adoption. RESULTS We describe the development of a new vector based on cowpea severe mosaic virus (CPSMV), a plus-strand RNA virus with its genome divided into two RNA segments, RNA1 and RNA2. This vector, designated FZ, incorporates a cloning site in the RNA2 cDNA, permitting insertion of nonviral sequences. When paired with an optimized RNA1 construct, FZ readily infects both Nicotiana benthamiana and soybean. As a result, FZ constructs destined for soybean can be first delivered to N. benthamiana in order to propagate the modified viruses to high titers. FZ-based silencing constructs induced robust silencing of phytoene desaturase genes in N. benthamiana, multiple soybean accessions, and cowpea. Meanwhile, FZ supported systemic expression of fluorescent proteins mNeonGreen and mCherry in N. benthamiana and soybean. Finally, FZ-mediated expression of the Arabidopsis transcription factor MYB75 caused N. benthamiana to bear brown leaves and purple, twisted flowers, indicating that MYB75 retained the function of activating anthocyanin synthesis pathways in a different plant. CONCLUSIONS The new CPSMV-derived FZ vector provides a convenient and versatile soybean functional genomics tool that is expected to accelerate the characterization of soybean genes controlling crucial productivity traits.
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Affiliation(s)
- Fides Angeli Zaulda
- Department of Plant Pathology, The Ohio State University, Wooster, OH, 44691, USA
| | - Seung Hyun Yang
- Department of Plant Pathology, The Ohio State University, Wooster, OH, 44691, USA
| | - Junping Han
- Department of Plant Pathology, The Ohio State University, Wooster, OH, 44691, USA
| | | | - Anne Dorrance
- Department of Plant Pathology, The Ohio State University, Wooster, OH, 44691, USA
| | - Feng Qu
- Department of Plant Pathology, The Ohio State University, Wooster, OH, 44691, USA.
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6
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Perdoncini Carvalho C, Ren R, Han J, Qu F. Natural Selection, Intracellular Bottlenecks of Virus Populations, and Viral Superinfection Exclusion. Annu Rev Virol 2022; 9:121-137. [PMID: 35567296 DOI: 10.1146/annurev-virology-100520-114758] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Natural selection acts on cellular organisms by ensuring the genes responsible for an advantageous phenotype consistently reap the phenotypic advantage. This is possible because reproductive cells of these organisms are almost always haploid, separating the beneficial gene from its rival allele at every generation. How natural selection acts on plus-strand RNA viruses is unclear because these viruses frequently load host cells with numerous genome copies and replicate thousands of progeny genomes in each cell. Recent studies suggest that these viruses encode the Bottleneck, Isolate, Amplify, Select (BIAS) mechanism that blocks all but a few viral genome copies from replication, thus creating the environment in which the bottleneck-escaping viral genome copies are isolated from each other, allowing natural selection to reward beneficial mutations and purge lethal errors. This BIAS mechanism also blocks the genomes of highly homologous superinfecting viruses, thus explaining cellular-level superinfection exclusion. Expected final online publication date for the Annual Review of Virology, Volume 9 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
| | - Ruifan Ren
- Department of Plant Pathology, The Ohio State University, Wooster, Ohio, USA;
| | - Junping Han
- Department of Plant Pathology, The Ohio State University, Wooster, Ohio, USA;
| | - Feng Qu
- Department of Plant Pathology, The Ohio State University, Wooster, Ohio, USA;
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7
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A Core35S Promoter of Cauliflower Mosaic Virus Drives More Efficient Replication of Turnip Crinkle Virus. PLANTS 2021; 10:plants10081700. [PMID: 34451745 PMCID: PMC8399983 DOI: 10.3390/plants10081700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 08/04/2021] [Accepted: 08/09/2021] [Indexed: 11/17/2022]
Abstract
The 35S promoter with a duplicated enhancer (frequently referred to as 2X35S) is a strong dicotyledonous plant-specific promoter commonly used in generating transgenic plants to enable high-level expression of genes of interest. It is also used to drive the initiation of RNA virus replication from viral cDNA, with the consensus understanding that high levels of viral RNA production powered by 2X35S permit a more efficient initiation of virus replication. Here, we showed that the exact opposite is true. We found that, compared to the Core35S promoter, the 2X35S promoter-driven initiation of turnip crinkle virus (TCV) infection was delayed by at least 24 h. We first compared three versions of 35S promoter, namely 2X35S, 1X35S, and Core35S, for their ability to power the expression of a non-replicating green fluorescent protein (GFP) gene, and confirmed that 2X35S and Core35S correlated with the highest and lowest GFP expression, respectively. However, when inserted upstream of TCV cDNA, 2X35S-driven replication was not detected until 72 h post-inoculation (72 hpi) in inoculated leaves. By contrast, Core35S-driven replication was detected earlier at 48 hpi. A similar delay was also observed in systemically infected leaves (six versus four days post-inoculation). Combining our results, we hypothesized that the stronger 2X35S promoter might enable a higher accumulation of a TCV protein that became a repressor of TCV replication at higher cellular concentration. Extending from these results, we propose that the Core35S (or mini35S) promoter is likely a better choice for generating infectious cDNA clones of TCV.
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8
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Carpino C, Ferriol Safont I, Elvira‐González L, Medina V, Rubio L, Peri E, Davino S, Galipienso Torregrosa L. RNA2-encoded VP37 protein of Broad bean wilt virus 1 is a determinant of pathogenicity, host susceptibility, and a suppressor of post-transcriptional gene silencing. MOLECULAR PLANT PATHOLOGY 2020; 21:1421-1435. [PMID: 32936537 PMCID: PMC7549002 DOI: 10.1111/mpp.12979] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 07/02/2020] [Accepted: 07/02/2020] [Indexed: 06/01/2023]
Abstract
Broad bean wilt virus 1 (BBWV-1, genus Fabavirus, family Secoviridae) is a bipartite, single-stranded positive-sense RNA virus infecting many horticultural and ornamental crops worldwide. RNA1 encodes proteins involved in viral replication whereas RNA2 encodes two coat proteins (the large and small coat proteins) and two putative movement proteins (MPs) of different sizes with overlapping C-terminal regions. In this work, we determined the role played by the small putative BBWV-1 MP (VP37) on virus pathogenicity, host specificity, and suppression of post-transcriptional gene silencing (PTGS). We engineered a BBWV-1 35S-driven full-length cDNA infectious clone corresponding to BBWV-1 RNA1 and RNA2 (pBBWV1-Wt) and generated a mutant knocking out VP37 (pBBWV1-G492C). Agroinfiltration assays showed that pBBWV1-Wt, as the original BBWV-1 isolate, infected broad bean, tomato, pepper, and Nicotiana benthamiana, whereas pBBWV1-G492C did not infect pepper and tomato systemically. Also, pBBWV1-G492C induced milder symptoms in broad bean and N. benthamiana than pBBWV1-Wt. Differential retrotranscription and amplification of the (+) and (-) strands showed that pBBWV1-G492C replicated in the agroinfiltrated leaves of pepper but not in tomato. All this suggests that VP37 is a determinant of pathogenicity and host specificity. Transient expression of VP37 through a potato virus X (PVX) vector enhanced PVX symptoms and induced systemic necrosis associated with programmed cell death in N. benthamiana plants. Finally, VP37 was identified as a viral suppressor of RNA silencing by transient expression in N. benthamiana 16c plants and movement complementation of a viral construct based on turnip crinkle virus (pTCV-GFP).
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Affiliation(s)
- Caterina Carpino
- Instituto Valenciano de Investigaciones AgrariasValenciaSpain
- Department of Agricultural, Food and Forestry ScienceUniversity of PalermoPalermoItaly
| | | | - Laura Elvira‐González
- Instituto Valenciano de Investigaciones AgrariasValenciaSpain
- Departamento de BiotecnologíaEscuela Técnica Superior de Ingeniería NaturalUniversitat Politècnica de ValènciaValenciaSpain
| | - Vicente Medina
- Departamento de Producción Vegetal y Ciencia ForestalUniversitat de LleidaLleidaSpain
| | - Luis Rubio
- Instituto Valenciano de Investigaciones AgrariasValenciaSpain
| | - Ezio Peri
- Department of Agricultural, Food and Forestry ScienceUniversity of PalermoPalermoItaly
| | - Salvatore Davino
- Department of Agricultural, Food and Forestry ScienceUniversity of PalermoPalermoItaly
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9
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Variability Studies of Two Prunus-Infecting Fabaviruses with the Aid of High-Throughput Sequencing. Viruses 2018; 10:v10040204. [PMID: 29670059 PMCID: PMC5923498 DOI: 10.3390/v10040204] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 04/12/2018] [Accepted: 04/14/2018] [Indexed: 02/05/2023] Open
Abstract
During their lifetime, perennial woody plants are expected to face multiple infection events. Furthermore, multiple genotypes of individual virus species may co-infect the same host. This may eventually lead to a situation where plants harbor complex communities of viral species/strains. Using high-throughput sequencing, we describe co-infection of sweet and sour cherry trees with diverse genomic variants of two closely related viruses, namely prunus virus F (PrVF) and cherry virus F (CVF). Both viruses are most homologous to members of the Fabavirus genus (Secoviridae family). The comparison of CVF and PrVF RNA2 genomic sequences suggests that the two viruses may significantly differ in their expression strategy. Indeed, similar to comoviruses, the smaller genomic segment of PrVF, RNA2, may be translated in two collinear proteins while CVF likely expresses only the shorter of these two proteins. Linked with the observation that identity levels between the coat proteins of these two viruses are significantly below the family species demarcation cut-off, these findings support the idea that CVF and PrVF represent two separate Fabavirus species.
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10
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Gedling CR, Ali EM, Gunadi A, Finer JJ, Xie K, Liu Y, Yoshikawa N, Qu F, Dorrance AE. Improved apple latent spherical virus-induced gene silencing in multiple soybean genotypes through direct inoculation of agro-infiltrated Nicotiana benthamiana extract. PLANT METHODS 2018. [PMID: 29527233 PMCID: PMC5838930 DOI: 10.1186/s13007-018-0286-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
BACKGROUND Virus induced gene silencing (VIGS) is a powerful genomics tool for interrogating the function of plant genes. Unfortunately, VIGS vectors often produce disease symptoms that interfere with the silencing phenotypes of target genes, or are frequently ineffective in certain plant genotypes or tissue types. This is especially true in crop plants like soybean [Glycine max (L.) Merr]. To address these shortcomings, we modified the inoculation procedure of a VIGS vector based on Apple latent spherical virus (ALSV). The efficacy of this new procedure was assessed in 19 soybean genotypes using a soybean Phytoene desaturase (GmPDS1) gene as the VIGS target. Silencing of GmPDS1 was easily scored as photo-bleached leaves and/or stems. RESULTS In this report, the ALSV VIGS vector was modified by mobilizing ALSV cDNAs into a binary vector compatible with Agrobacterium tumefaciens-mediated delivery, so that VIGS-triggering ALSV variants could be propagated in agro-infiltrated Nicotiana benthamiana leaves. Homogenate of these N. benthamiana leaves was then applied directly onto the unifoliate of young soybean seedlings to initiate systemic gene silencing. This rapid inoculation method bypassed the need for a particle bombardment apparatus. Among the 19 soybean genotypes evaluated with this new method, photo-bleaching indicative of GmPDS1 silencing was observed in nine, with two exhibiting photo-bleaching in 100% of the inoculated individuals. ALSV RNA was detected in pods, embryos, stems, leaves, and roots in symptomatic plants of four genotypes. CONCLUSIONS This modified protocol allowed for inoculation of soybean plants via simple mechanical rubbing with the homogenate of N. benthamiana leaves agro-infiltrated with ALSV VIGS constructs. More importantly, inoculated plants showed no apparent virus disease symptoms which could otherwise interfere with VIGS phenotypes. This streamlined procedure expanded this functional genomics tool to nine soybean genotypes.
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Affiliation(s)
- C. R. Gedling
- Department of Plant Pathology, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691 USA
| | - E. M. Ali
- Department of Plant Pathology, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691 USA
- Present Address: Washington State University, 1100 N Western Ave., Wenatchee, WA 98801 USA
| | - A. Gunadi
- Department of Horticulture and Crop Science, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691 USA
| | - J. J. Finer
- Department of Horticulture and Crop Science, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691 USA
| | - K. Xie
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing, China
| | - Y. Liu
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084 China
| | - N. Yoshikawa
- Plant Pathology Lab, Facility of Agriculture, Iwate University, Morioka, Japan
| | - F. Qu
- Department of Plant Pathology, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691 USA
| | - A. E. Dorrance
- Department of Plant Pathology, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691 USA
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11
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Guo J, Han J, Lin J, Finer J, Dorrance A, Qu F. Functionally interchangeable cis-acting RNA elements in both genome segments of a picorna-like plant virus. Sci Rep 2017; 7:1017. [PMID: 28432346 PMCID: PMC5430698 DOI: 10.1038/s41598-017-01243-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 03/23/2017] [Indexed: 11/09/2022] Open
Abstract
Cis-acting RNA structures in the genomes of RNA viruses play critical roles in viral infection, yet their importance in the bipartite genomes of the picorna-like, plant-infecting comoviruses has not been carefully investigated. We previously characterized SLC, a stem-loop structure in the 5' untranslated region (UTR) of the bean pod mottle comovirus (BPMV) RNA2, and found it to be essential for RNA2 accumulation in infected cells. Here we report the identification of SL1, a similar cis-acting element in the other BPMV genome segment - RNA1. SL1 encompasses a portion of RNA1 5' UTR but extends into the coding sequence for nine nucleotides, thus was missed in the previous study. While the stems of SL1 and SLC share little sequence similarity, their end loops are of the same size and identical for 11 of 15 nucleotides. Importantly, SL1 and SLC are functionally interchangeable, and separate exchanges of the stem and loop portions were likewise well tolerated. By contrast, the conserved loop sequence tolerated minimal perturbations. Finally, stem-loop structures with similar configurations were identified in two other comoviruses. Therefore, SL1 and SLC are likely essential comoviral RNA structures that play a conserved function in viral infection cycles.
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Affiliation(s)
- Jiangbo Guo
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH, 44691, USA.,School of Mathematics, Physics and Biological Engineering, Inner Mongolia University of Science and Technology, Baotou, China
| | - Junping Han
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH, 44691, USA
| | - Junyan Lin
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH, 44691, USA.,Joint Genome Institute, Department of Energy, 2800 Mitchell Drive, Walnut Creek, CA, 94598, USA
| | - John Finer
- Department of Horticulture and Crop Science, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH, 44691, USA
| | - Anne Dorrance
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH, 44691, USA
| | - Feng Qu
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH, 44691, USA.
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12
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Stewart LR, Jarugula S, Zhao Y, Qu F, Marty D. Identification of a maize chlorotic dwarf virus silencing suppressor protein. Virology 2017; 504:88-95. [PMID: 28160664 DOI: 10.1016/j.virol.2016.11.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 11/23/2016] [Accepted: 11/25/2016] [Indexed: 11/27/2022]
Abstract
Maize chlorotic dwarf virus (MCDV), a member of the genus Waikavirus, family Secoviridae, has a 11784 nt (+)ssRNA genome that encodes a 389kDa proteolytically processed polyprotein. We show that the N-terminal 78kDa polyprotein (R78) of MCDV acts as a suppressor of RNA silencing in a well-established assay system. We further demonstrate that R78 is cleaved by the viral 3C-like protease into 51 and 27kDa proteins (p51 and p27), and that p51 is responsible for silencing suppressor activity. Silencing suppressor activity of R78 is conserved in three divergent MCDV strains (MCDV-Severe, MCDV-M1, and MCDV-Tennessee), as well as the waikavirus Bellflower vein chlorosis virus, but was not detected for orthologous protein of Rice tungro spherical virus (RTSV-A) or the similarly-positioned protein from the sequivirus Parsnip yellow fleck virus (PYFV). This is the first identification of a virus suppressor of RNA silencing encoded by a waikavirus.
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Affiliation(s)
- Lucy R Stewart
- USDA-ARS Corn, Soybean and Wheat Quality Research Unit, Wooster, OH, USA; Department of Plant Pathology, Ohio State University, Wooster, OH, USA.
| | - Sridhar Jarugula
- Department of Plant Pathology, Ohio State University, Wooster, OH, USA
| | - Yujing Zhao
- Department of Plant Pathology, Ohio State University, Wooster, OH, USA
| | - Feng Qu
- Department of Plant Pathology, Ohio State University, Wooster, OH, USA
| | - DeeMarie Marty
- USDA-ARS Corn, Soybean and Wheat Quality Research Unit, Wooster, OH, USA
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Ferriol I, Silva Junior D, Nigg J, Zamora-Macorra E, Falk B. Identification of the cleavage sites of the RNA2-encoded polyproteins for two members of the genus Torradovirus by N-terminal sequencing of the virion capsid proteins. Virology 2016; 498:109-115. [DOI: 10.1016/j.virol.2016.08.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 08/15/2016] [Accepted: 08/17/2016] [Indexed: 11/16/2022]
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14
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Random Plant Viral Variants Attain Temporal Advantages During Systemic Infections and in Turn Resist other Variants of the Same Virus. Sci Rep 2015; 5:15346. [PMID: 26481091 PMCID: PMC4612314 DOI: 10.1038/srep15346] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 09/22/2015] [Indexed: 01/19/2023] Open
Abstract
Infection of plants with viruses containing multiple variants frequently leads to dominance by a few random variants in the systemically infected leaves (SLs), for which a plausible explanation is lacking. We show here that SL dominance by a given viral variant is adequately explained by its fortuitous lead in systemic spread, coupled with its resistance to superinfection by other variants. We analyzed the fate of a multi-variant turnip crinkle virus (TCV) population in Arabidopsis and N. benthamiana plants. Both wild-type and RNA silencing-defective plants displayed a similar pattern of random dominance by a few variant genotypes, thus discounting a prominent role for RNA silencing. When introduced to plants sequentially as two subpopulations, a twelve-hour head-start was sufficient for the first set to dominate. Finally, SLs of TCV-infected plants became highly resistant to secondary invasions of another TCV variant. We propose that random distribution of variant foci on inoculated leaves allows different variants to lead systemic movement in different plants. The leading variants then colonize large areas of SLs, and resist the superinfection of lagging variants in the same areas. In conclusion, superinfection resistance is the primary driver of random enrichment of viral variants in systemically infected plants.
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Kazakov T, Yang F, Ramanathan HN, Kohlway A, Diamond MS, Lindenbach BD. Hepatitis C virus RNA replication depends on specific cis- and trans-acting activities of viral nonstructural proteins. PLoS Pathog 2015; 11:e1004817. [PMID: 25875808 PMCID: PMC4395149 DOI: 10.1371/journal.ppat.1004817] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 03/18/2015] [Indexed: 02/07/2023] Open
Abstract
Many positive-strand RNA viruses encode genes that can function in trans, whereas other genes are required in cis for genome replication. The mechanisms underlying trans- and cis-preferences are not fully understood. Here, we evaluate this concept for hepatitis C virus (HCV), an important cause of chronic liver disease and member of the Flaviviridae family. HCV encodes five nonstructural (NS) genes that are required for RNA replication. To date, only two of these genes, NS4B and NS5A, have been trans-complemented, leading to suggestions that other replicase genes work only in cis. We describe a new quantitative system to measure the cis- and trans-requirements for HCV NS gene function in RNA replication and identify several lethal mutations in the NS3, NS4A, NS4B, NS5A, and NS5B genes that can be complemented in trans, alone or in combination, by expressing the NS3-5B polyprotein from a synthetic mRNA. Although NS5B RNA binding and polymerase activities can be supplied in trans, NS5B protein expression was required in cis, indicating that NS5B has a cis-acting role in replicase assembly distinct from its known enzymatic activity. Furthermore, the RNA binding and NTPase activities of the NS3 helicase domain were required in cis, suggesting that these activities play an essential role in RNA template selection. A comprehensive complementation group analysis revealed functional linkages between NS3-4A and NS4B and between NS5B and the upstream NS3-5A genes. Finally, NS5B polymerase activity segregated with a daclatasvir-sensitive NS5A activity, which could explain the synergy of this antiviral compound with nucleoside analogs in patients. Together, these studies define several new aspects of HCV replicase structure-function, help to explain the potency of HCV-specific combination therapies, and provide an experimental framework for the study of cis- and trans-acting activities in positive-strand RNA virus replication more generally.
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Affiliation(s)
- Teymur Kazakov
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Feng Yang
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Harish N. Ramanathan
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Andrew Kohlway
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
| | - Michael S. Diamond
- Departments of Medicine, Molecular Microbiology, and Pathology & Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Brett D. Lindenbach
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
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