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Muellender MM, Savenkov EI, Reichelt M, Varrelmann M, Liebe S. The Virulence Factor p25 of Beet Necrotic Yellow Vein Virus Interacts With Multiple Aux/IAA Proteins From Beta vulgaris: Implications for Rhizomania Development. Front Microbiol 2022; 12:809690. [PMID: 35140697 PMCID: PMC8819154 DOI: 10.3389/fmicb.2021.809690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 12/20/2021] [Indexed: 11/13/2022] Open
Abstract
Rhizomania caused by Beet necrotic yellow vein virus (BNYVV) is characterized by excessive lateral root (LR) formation. Auxin-mediated degradation of Aux/IAA transcriptional repressors stimulates gene regulatory networks leading to LR organogenesis and involves several Aux/IAA proteins acting at distinctive stages of LR development. Previously, we showed that BNYVV p25 virulence factor interacts with BvIAA28, a transcriptional repressor acting at early stages of LR initiation. The evidence suggested that p25 inhibits BvIAA28 nuclear localization, thus, de-repressing transcriptional network leading to LR initiation. However, it was not clear whether p25 interacts with other Aux/IAA proteins. Here, by adopting bioinformatics, in vitro and in vivo protein interaction approaches we show that p25 interacts also with BvIAA2 and BvIAA6. Moreover, we confirmed that the BNYVV infection is, indeed, accompanied by an elevated auxin level in the infected LRs. Nevertheless, expression levels of BvIAA2 and BvIAA6 remained unchanged upon BNYVV infection. Mutational analysis indicated that interaction of p25 with either BvIAA2 or BvIAA6 requires full-length proteins as even single amino acid residue substitutions abolished the interactions. Compared to p25-BvIAA28 interaction that leads to redistribution of BvIAA28 into cytoplasm, both BvIAA2 and BvIAA6 remained confined into the nucleus regardless of the presence of p25 suggesting their stabilization though p25 interaction. Overexpression of p25-interacting partners (BvIAA2, BvIAA6 and BvIAA28) in Nicotiana benthamiana induced an auxin-insensitive phenotype characterized by plant dwarfism and dramatically reduced LR development. Thus, our work reveals a distinct class of transcriptional repressors targeted by p25.
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Affiliation(s)
| | - Eugene I. Savenkov
- Department of Plant Biology, Uppsala BioCenter SLU, Swedish University of Agricultural Sciences, Linnean Center for Plant Biology, Uppsala, Sweden
| | - Michael Reichelt
- Max Planck Institute for Chemical Ecology, Department of Biochemistry, Jena, Germany
| | - Mark Varrelmann
- Institute of Sugar Beet Research, Department of Phytopathology, Göttingen, Germany
| | - Sebastian Liebe
- Institute of Sugar Beet Research, Department of Phytopathology, Göttingen, Germany
- *Correspondence: Sebastian Liebe,
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Pasin F, Daròs JA, Tzanetakis IE. OUP accepted manuscript. FEMS Microbiol Rev 2022; 46:6534904. [PMID: 35195244 PMCID: PMC9249622 DOI: 10.1093/femsre/fuac011] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 02/02/2022] [Accepted: 02/08/2022] [Indexed: 11/17/2022] Open
Abstract
Potyviridae, the largest family of known RNA viruses (realm Riboviria), belongs to the picorna-like supergroup and has important agricultural and ecological impacts. Potyvirid genomes are translated into polyproteins, which are in turn hydrolyzed to release mature products. Recent sequencing efforts revealed an unprecedented number of potyvirids with a rich variability in gene content and genomic layouts. Here, we review the heterogeneity of non-core modules that expand the structural and functional diversity of the potyvirid proteomes. We provide a family-wide classification of P1 proteinases into the functional Types A and B, and discuss pretty interesting sweet potato potyviral ORF (PISPO), putative zinc fingers, and alkylation B (AlkB)—non-core modules found within P1 cistrons. The atypical inosine triphosphate pyrophosphatase (ITPase/HAM1), as well as the pseudo tobacco mosaic virus-like coat protein (TMV-like CP) are discussed alongside homologs of unrelated virus taxa. Family-wide abundance of the multitasking helper component proteinase (HC-pro) is revised. Functional connections between non-core modules are highlighted to support host niche adaptation and immune evasion as main drivers of the Potyviridae evolutionary radiation. Potential biotechnological and synthetic biology applications of potyvirid leader proteinases and non-core modules are finally explored.
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Affiliation(s)
- Fabio Pasin
- Corresponding author: Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas-Universitat Politècnica de València (CSIC-UPV), UPV Building 8E, Ingeniero Fausto Elio, 46011 Valencia, Spain. E-mail:
| | - José-Antonio Daròs
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas-Universitat Politècnica de València (CSIC-UPV), 46011 Valencia, Spain
| | - Ioannis E Tzanetakis
- Department of Entomology and Plant Pathology, Division of Agriculture, University of Arkansas System, 72701 Fayetteville, AR, USA
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Kumar KK, Varanavasiappan S, Arul L, Kokiladevi E, Sudhakar D. Strategies for Efficient RNAi-Based Gene Silencing of Viral Genes for Disease Resistance in Plants. Methods Mol Biol 2022; 2408:23-35. [PMID: 35325414 DOI: 10.1007/978-1-0716-1875-2_2] [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] [Indexed: 06/14/2023]
Abstract
RNA interference (RNAi) is an evolutionarily conserved gene silencing mechanism in eukaryotes including fungi, plants, and animals. In plants, gene silencing regulates gene expression, provides genome stability, and protect against invading viruses. During plant virus interaction, viral genome derived siRNAs (vsiRNA) are produced to mediate gene silencing of viral genes to prevent virus multiplication. After the discovery of RNAi phenomenon in eukaryotes, it is used as a powerful tool to engineer plant viral disease resistance against both RNA and DNA viruses. Despite several successful reports on employing RNA silencing methods to engineer plant for viral disease resistance, only a few of them have reached the commercial stage owing to lack of complete protection against the intended virus. Based on the knowledge accumulated over the years on genetic engineering for viral disease resistance, there is scope for effective viral disease control through careful design of RNAi gene construct. The selection of target viral gene(s) for developing the hairpin RNAi (hp-RNAi) construct is very critical for effective protection against the viral disease. Different approaches and bioinformatics tools which can be employed for effective target selection are discussed. The selection of suitable target regions for RNAi vector construction can help to achieve a high level of transgenic virus resistance.
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Affiliation(s)
- Krish K Kumar
- Department of Plant Biotechnology, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India.
| | - Shanmugam Varanavasiappan
- Department of Plant Biotechnology, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India.
| | - Loganathan Arul
- Department of Plant Biotechnology, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India
| | - Easwaran Kokiladevi
- Department of Plant Biotechnology, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India
| | - Duraialagaraja Sudhakar
- Department of Plant Biotechnology, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India
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Xu XJ, Zhu Q, Jiang SY, Yan ZY, Geng C, Tian YP, Li XD. Development and Evaluation of Stable Sugarcane Mosaic Virus Mild Mutants for Cross-Protection Against Infection by Severe Strain. FRONTIERS IN PLANT SCIENCE 2021; 12:788963. [PMID: 34975975 PMCID: PMC8718998 DOI: 10.3389/fpls.2021.788963] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 12/01/2021] [Indexed: 05/26/2023]
Abstract
Sugarcane mosaic virus (SCMV; genus Potyvirus) induces maize dwarf mosaic disease that has caused serious yield losses of maize in China. Cross-protection is one of the efficient strategies to fight against severe virus strains. Although many mild strains have been identified, the spontaneous mutation is one of the challenging problems affecting their application in cross-protection. In this study, we found that the substitution of cysteine (C) at positions 57 or 60 in the zinc finger-like motif of HC-Pro with alanine (A; C57A or C60A) significantly reduced its RNA silencing suppression activity and SCMV virulence. To reduce the risk of mild strains mutating to virulent ones by reverse or complementary mutations, we obtained attenuated SCMV mutants with double-mutations in the zinc finger-like and FRNK motifs of HC-Pro and evaluated their potential application in cross-protection. The results showed that the maize plants infected with FKNK/C60A double-mutant showed symptomless until 95 days post-inoculation and FKNK/C60A cross-protected plants displayed high resistance to severe SCMV strain. This study provides theoretical and material bases for the control of SCMV through cross-protection.
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Lindenau S, Winter S, Margaria P. The Amino-Proximal Region of the Coat Protein of Cucumber Vein Yellowing Virus (Family Potyviridae) Affects the Infection Process and Whitefly Transmission. PLANTS (BASEL, SWITZERLAND) 2021; 10:plants10122771. [PMID: 34961241 PMCID: PMC8706179 DOI: 10.3390/plants10122771] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/10/2021] [Accepted: 12/13/2021] [Indexed: 05/02/2023]
Abstract
Most plant viruses rely on vector transmission for their spread and specific interactions between vector and virus have evolved to regulate this relationship. The whitefly Bemisia tabaci- transmitted cucumber vein yellowing virus (CVYV; genus Ipomovirus, family Potyviridae) is endemic in the Mediterranean Basin, where it causes significant losses in cucurbit crops. In this study, the role of the coat protein (CP) of CVYV for B. tabaci transmission and plant infection was investigated using a cloned and infectious CVYV cDNA and a collection of point and deletion mutants derived from this clone. Whitefly transmission of CVYV was abolished in a deletion mutant lacking amino acids in position 93-105 of the CP. This deletion mutant caused more severe disease symptoms compared to the cDNA clone representing the wild-type (wt) virus and movement efficiency was likewise affected. Two virus mutants carrying a partially restored CP were transmissible and showed symptoms comparable to the wt virus. Collectively, our data demonstrate that the N-terminus of the CVYV CP is a determinant for transmission by the whitefly vector and is involved in plant infection and symptom expression.
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56
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García B, Bedoya L, García JA, Rodamilans B. An Importin-β-like Protein from Nicotiana benthamiana Interacts with the RNA Silencing Suppressor P1b of the Cucumber Vein Yellowing Virus, Modulating Its Activity. Viruses 2021; 13:2406. [PMID: 34960675 PMCID: PMC8706682 DOI: 10.3390/v13122406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 11/26/2021] [Accepted: 11/29/2021] [Indexed: 11/26/2022] Open
Abstract
During a plant viral infection, host-pathogen interactions are critical for successful replication and propagation of the virus through the plant. RNA silencing suppressors (RSSs) are key players of this interplay, and they often interact with different host proteins, developing multiple functions. In the Potyviridae family, viruses produce two main RSSs, HCPro and type B P1 proteins. We focused our efforts on the less known P1b of cucumber vein yellowing virus (CVYV), a type B P1 protein, to try to identify possible factors that could play a relevant role during viral infection. We used a chimeric expression system based on plum pox virus (PPV) encoding a tagged CVYV P1b in place of the canonical HCPro. We used that tag to purify P1b in Nicotiana-benthamiana-infected plants and identified by mass spectrometry an importin-β-like protein similar to importin 7 of Arabidopsis thaliana. We further confirmed the interaction by bimolecular fluorescence complementation assays and defined its nuclear localization in the cell. Further analyses showed a possible role of this N. benthamiana homolog of Importin 7 as a modulator of the RNA silencing suppression activity of P1b.
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Affiliation(s)
| | | | | | - Bernardo Rodamilans
- Centro Nacional de Biotecnología CNB, Consejo Superior de Investigaciones Científicas CSIC, 28049 Madrid, Spain; (B.G.); (L.B.); (J.A.G.)
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57
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Abstract
The NIa protease of potyviruses is a chymotrypsin-like cysteine protease related to the picornavirus 3C protease. It is also a multifunctional protein known to play multiple roles during virus infection. Picornavirus 3C proteases cleave hundreds of host proteins to facilitate virus infection. However, whether or not potyvirus NIa proteases cleave plant proteins has so far not been tested. Regular expression search using the cleavage site consensus sequence [EQN]xVxH[QE]/[SGTA] for the plum pox virus (PPV) protease identified 90 to 94 putative cleavage events in the proteomes of Prunus persica (a crop severely affected by PPV), Arabidopsis thaliana, and Nicotiana benthamiana (two experimental hosts). In vitro processing assays confirmed cleavage of six A. thaliana and five P. persica proteins by the PPV protease. These proteins were also cleaved in vitro by the protease of turnip mosaic virus (TuMV), which has a similar specificity. We confirmed in vivo cleavage of a transiently expressed tagged version of AtEML2, an EMSY-like protein belonging to a family of nuclear histone readers known to be involved in pathogen resistance. Cleavage of AtEML2 was efficient and was observed in plants that coexpressed the PPV or TuMV NIa proteases or in plants that were infected with TuMV. We also showed partial in vivo cleavage of AtDUF707, a membrane protein annotated as lysine ketoglutarate reductase trans-splicing protein. Although cleavage of the corresponding endogenous plant proteins remains to be confirmed, the results show that a plant virus protease can cleave host proteins during virus infection and highlight a new layer of plant-virus interactions. IMPORTANCE Viruses are highly adaptive and use multiple molecular mechanisms to highjack or modify the cellular resources to their advantage. They must also counteract or evade host defense responses. One well-characterized mechanism used by vertebrate viruses is the proteolytic cleavage of host proteins to inhibit the activities of these proteins and/or to produce cleaved protein fragments that are beneficial to the virus infection cycle. Even though almost half of the known plant viruses encode at least one protease, it was not known whether plant viruses employ this strategy. Using an in silico prediction approach and the well-characterized specificity of potyvirus NIa proteases, we were able to identify hundreds of putative cleavage sites in plant proteins, several of which were validated by downstream experiments. It can be anticipated that many other plant virus proteases also cleave host proteins and that the identification of these cleavage events will lead to novel antiviral strategies.
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58
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Tsu BV, Fay EJ, Nguyen KT, Corley MR, Hosuru B, Dominguez VA, Daugherty MD. Running With Scissors: Evolutionary Conflicts Between Viral Proteases and the Host Immune System. Front Immunol 2021; 12:769543. [PMID: 34790204 PMCID: PMC8591160 DOI: 10.3389/fimmu.2021.769543] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 10/08/2021] [Indexed: 12/28/2022] Open
Abstract
Many pathogens encode proteases that serve to antagonize the host immune system. In particular, viruses with a positive-sense single-stranded RNA genome [(+)ssRNA], including picornaviruses, flaviviruses, and coronaviruses, encode proteases that are not only required for processing viral polyproteins into functional units but also manipulate crucial host cellular processes through their proteolytic activity. Because these proteases must cleave numerous polyprotein sites as well as diverse host targets, evolution of these viral proteases is expected to be highly constrained. However, despite this strong evolutionary constraint, mounting evidence suggests that viral proteases such as picornavirus 3C, flavivirus NS3, and coronavirus 3CL, are engaged in molecular 'arms races' with their targeted host factors, resulting in host- and virus-specific determinants of protease cleavage. In cases where protease-mediated cleavage results in host immune inactivation, recurrent host gene evolution can result in avoidance of cleavage by viral proteases. In other cases, such as recently described examples in NLRP1 and CARD8, hosts have evolved 'tripwire' sequences that mimic protease cleavage sites and activate an immune response upon cleavage. In both cases, host evolution may be responsible for driving viral protease evolution, helping explain why viral proteases and polyprotein sites are divergent among related viruses despite such strong evolutionary constraint. Importantly, these evolutionary conflicts result in diverse protease-host interactions even within closely related host and viral species, thereby contributing to host range, zoonotic potential, and pathogenicity of viral infection. Such examples highlight the importance of examining viral protease-host interactions through an evolutionary lens.
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Affiliation(s)
| | | | | | | | | | | | - Matthew D. Daugherty
- Division of Biological Sciences, University of California, San Diego, CA, United States
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59
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Modulation of Expression of PVY NTN RNA-Dependent RNA Polymerase (NIb) and Heat Shock Cognate Host Protein HSC70 in Susceptible and Hypersensitive Potato Cultivars. Vaccines (Basel) 2021; 9:vaccines9111254. [PMID: 34835185 PMCID: PMC8619674 DOI: 10.3390/vaccines9111254] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 10/18/2021] [Accepted: 10/26/2021] [Indexed: 11/16/2022] Open
Abstract
Potato virus Y (PVY) belongs to the genus Potyvirus and is considered to be one of the most harmful and important plant pathogens. Its RNA-dependent RNA polymerase (RdRp) is known as nuclear inclusion protein b (NIb). The recent findings show that the genome of PVY replicates in the cytoplasm of the plant cell by binding the virus replication complex to the membranous structures of different organelles. In some potyviruses, NIb has been found to be localized in the nucleus and associated with the endoplasmic reticulum membranes. Moreover, NIb has been shown to interact with other host proteins that are particularly involved in promoting the virus infection cycle, such as the heat shock proteins (HSPs). HSP70 is the most conserved among the five major HSP families that are known to affect the plant-pathogen interactions. Some plant viruses can induce the production of HSP70 during the development of infection. To understand the molecular mechanisms underlying the interactive response to PVYNTN (necrotic tuber necrosis strain of PVY), the present study focused on StHSC70-8 and PVYNTN-NIb gene expression via localization of HSC70 and NIb proteins during compatible (susceptible) and incompatible (hypersensitive) potato-PVYNTN interactions. Our results demonstrate that NIb and HSC70 are involved in the response to PVYNTN infections and probably cooperate at some stages of the virus infection cycle. Enhanced deposition of HSC70 proteins during the infection cycle was associated with the dynamic induction of PVYNTN-NIb gene expression and NIb localization during susceptible infections. In hypersensitive response (HR), a significant increase in HSC70 expression was observed up to 3 days post-inoculation (dpi) in the nucleus and chloroplasts. Thereafter, between 3 and 21 dpi, the deposition of NIb decreased, which can be attributed to a reduction in the levels of both virus accumulation and PVYNTN-NIb gene expression. Therefore, we postulate that increase in the expression of both StHSC70-8 and PVYNTN-NIb induces the PVY infection during susceptible infections. In contrast, during HRs, HSC70 cooperates with PVYNTN only at the early stages of interaction and mediates the defense response signaling pathway at the later stages of infection.
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60
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Investigating the Viral Suppressor HC-Pro Inhibiting Small RNA Methylation through Functional Comparison of HEN1 in Angiosperm and Bryophyte. Viruses 2021; 13:v13091837. [PMID: 34578418 PMCID: PMC8473176 DOI: 10.3390/v13091837] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/09/2021] [Accepted: 09/09/2021] [Indexed: 12/27/2022] Open
Abstract
In plants, HEN1-facilitated methylation at 3′ end ribose is a critical step of small-RNA (sRNA) biogenesis. A mutant of well-studied Arabidopsis HEN1 (AtHEN1), hen1-1, showed a defective developmental phenotype, indicating the importance of sRNA methylation. Moreover, Marchantia polymorpha has been identified to have a HEN1 ortholog gene (MpHEN1); however, its function remained unfathomed. Our in vivo and in vitro data have shown MpHEN1 activity being comparable with AtHEN1, and their substrate specificity towards duplex microRNA (miRNA) remained consistent. Furthermore, the phylogenetic tree and multiple alignment highlighted the conserved molecular evolution of the HEN1 family in plants. The P1/HC-Pro of the turnip mosaic virus (TuMV) is a known RNA silencing suppressor and inhibits HEN1 methylation of sRNAs. Here, we report that the HC-Pro physically binds with AtHEN1 through FRNK motif, inhibiting HEN1’s methylation activity. Moreover, the in vitro EMSA data indicates GST-HC-Pro of TuMV lacks sRNA duplex-binding ability. Surprisingly, the HC-Pro also inhibits MpHEN1 activity in a dosage-dependent manner, suggesting the possibility of interaction between HC-Pro and MpHEN1 as well. Further investigations on understanding interaction mechanisms of HEN1 and various HC-Pros can advance the knowledge of viral suppressors.
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Yang X, Li Y, Wang A. Research Advances in Potyviruses: From the Laboratory Bench to the Field. ANNUAL REVIEW OF PHYTOPATHOLOGY 2021; 59:1-29. [PMID: 33891829 DOI: 10.1146/annurev-phyto-020620-114550] [Citation(s) in RCA: 67] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Potyviruses (viruses in the genus Potyvirus, family Potyviridae) constitute the largest group of known plant-infecting RNA viruses and include many agriculturally important viruses that cause devastating epidemics and significant yield losses in many crops worldwide. Several potyviruses are recognized as the most economically important viral pathogens. Therefore, potyviruses are more studied than other groups of plant viruses. In the past decade, a large amount of knowledge has been generated to better understand potyviruses and their infection process. In this review, we list the top 10 economically important potyviruses and present a brief profile of each. We highlight recent exciting findings on the novel genome expression strategy and the biological functions of potyviral proteins and discuss recent advances in molecular plant-potyvirus interactions, particularly regarding the coevolutionary arms race. Finally, we summarize current disease control strategies, with a focus on biotechnology-based genetic resistance, and point out future research directions.
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Affiliation(s)
- Xiuling Yang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario N5V 4T3, Canada;
| | - Yinzi Li
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario N5V 4T3, Canada;
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario N5V 4T3, Canada;
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Ghosh D, M M, Chakraborty S. Impact of viral silencing suppressors on plant viral synergism: a global agro-economic concern. Appl Microbiol Biotechnol 2021; 105:6301-6313. [PMID: 34423406 DOI: 10.1007/s00253-021-11483-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/26/2021] [Accepted: 07/27/2021] [Indexed: 12/27/2022]
Abstract
Plant viruses are known for their devastating impact on global agriculture. These intracellular biotrophic pathogens can infect a wide variety of plant hosts all over the world. The synergistic association of plant viruses makes the situation more alarming. It usually promotes the replication, movement, and transmission of either or both the coexisting synergistic viral partners. Although plants elicit a robust antiviral immune reaction, including gene silencing, to limit these infamous invaders, viruses counter it by encoding viral suppressors of RNA silencing (VSRs). Growing evidence also suggests that VSRs play a driving role in mediating the plant viral synergism. This review briefly discusses the evil impacts of mixed infections, especially synergism, and then comprehensively describes the emerging roles of VSRs in mediating the synergistic association of plant viruses. KEY POINTS: • Synergistic associations of plant viruses have devastating impacts on global agriculture. • Viral suppressors of RNA silencing (VSRs) play key roles in driving plant viral synergism.
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Affiliation(s)
- Dibyendu Ghosh
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Malavika M
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Supriya Chakraborty
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
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63
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Zhang W, Qiu Y, Zhou L, Yin J, Wang L, Zhi H, Xu K. Development of a Viral RdRp-Assisted Gene Silencing System and Its Application in the Identification of Host Factors of Plant (+)RNA Virus. Front Microbiol 2021; 12:682921. [PMID: 34394029 PMCID: PMC8358433 DOI: 10.3389/fmicb.2021.682921] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 06/24/2021] [Indexed: 11/13/2022] Open
Abstract
Gene silencing induced by hairpin RNA or virus infection expression is one of the major tools in genetics studies in plants. However, when dealing with essential genes, virus-induced gene silencing (VIGS) and transgenic expression of hairpin RNA could lead to plant death, while transient expression of hairpin RNA in leaves is often less competent in downregulating target gene mRNA levels. Here, we developed a transient double-stranded RNA (dsRNA) expression system assisted by a modified viral RNA-dependent RNA polymerase (RdRp) in plant leaves. We show that this system is more effective in inducing gene silencing than the intron-spliced hairpin RNA expression. Furthermore, by using this system, we tested the role of the early secretory pathway during infection of Soybean mosaic potyvirus (SMV). We found that key components of the coat protein complex II vesicles are required for the multiplication of SMV. Overall, this dsRNA-based gene silencing system is effective in downregulating plant gene expression and can be used to identify host genes involved in plant-virus interactions.
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Affiliation(s)
- Wang Zhang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Yanglin Qiu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Lingyun Zhou
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Jinlong Yin
- National Center for Soybean Improvement, National Key Laboratory for Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Genetic Improvement of Soybean-Ministry of Agriculture, Nanjing Agricultural University, Nanjing, China
| | - Liqun Wang
- National Center for Soybean Improvement, National Key Laboratory for Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Genetic Improvement of Soybean-Ministry of Agriculture, Nanjing Agricultural University, Nanjing, China
| | - Haijian Zhi
- National Center for Soybean Improvement, National Key Laboratory for Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Genetic Improvement of Soybean-Ministry of Agriculture, Nanjing Agricultural University, Nanjing, China
| | - Kai Xu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, China
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P1 of Sweet Potato Feathery Mottle Virus Shows Strong Adaptation Capacity, Replacing P1-HCPro in a Chimeric Plum Pox Virus. J Virol 2021; 95:e0015021. [PMID: 33952634 DOI: 10.1128/jvi.00150-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Potyviridae is the largest family of plant RNA viruses. Their genomes are expressed through long polyproteins that are usually headed by the leader endopeptidase P1. This protein can be classified as type A or type B based on host proteolytic requirements and RNA silencing suppression (RSS) capacity. The main Potyviridae genus is Potyvirus, and a group of potyviruses infecting sweet potato presents an enlarged P1 protein with a polymerase slippage motif that produces an extra product termed P1N-PISPO. These two proteins display some RSS activity and are expressed followed by HCPro, which appears to be the main RNA silencing suppressor in these viruses. Here, we studied the behavior of the P1 protein of Sweet potato feathery mottle virus (SPFMV) using a viral system based on a canonical potyvirus, Plum pox virus (PPV), and discovered that this protein is able to replace both PPV P1 and HCPro. We also found that P1N-PISPO, produced after polymerase slippage, provides extra RNA silencing suppression capacity to SPFMV P1 in this viral context. In addition, the results showed that presence of two type A P1 proteins was detrimental for viral viability. The ample recombination spectrum that we found in the recovered viruses supports the strong adaptation capacity of P1 proteins and signals the N-terminal part of SPFMV P1 as essential for RSS activity. Further analyses provided data to add extra layers to the evolutionary history of sweet potato-infecting potyvirids. IMPORTANCE Plant viruses represent a major challenge for agriculture worldwide and Potyviridae, being the largest family of plant RNA viruses, is one of the primary players. P1, the leader endopeptidase, is a multifunctional protein that contributes to the successful spread of these viruses over a wide host range. Understanding how P1 proteins work, their dynamic interplay during viral infection, and their evolutionary path is critical for the development of strategic tools to fight the multiple diseases these viruses cause. We focused our efforts on the P1 protein of Sweet potato feathery mottle virus, which is coresponsible for the most devastating disease in sweet potato. The significance of our research is in understanding the capacity of this protein to perform several independent functions, using this knowledge to learn more about P1 proteins in general and the potyvirids infecting this host.
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Mondal S, Wintermantel WM, Gray SM. Virus and helper component interactions favour the transmission of recombinant potato virus Y strains. J Gen Virol 2021; 102. [PMID: 34161221 DOI: 10.1099/jgv.0.001620] [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: 11/18/2022] Open
Abstract
In recent years, several recombinant strains of potato virus Y, notably PVYNTN and PVYN:O have displaced the ordinary strain, PVYO, and emerged as the predominant strains affecting the USA potato crop. Previously we reported that recombinant strains were transmitted more efficiently than PVYO when they were acquired sequentially, regardless of acquisition order. In another recent study, we showed that PVYNTN binds preferentially to the aphid stylet over PVYO when aphids feed on a mixture of PVYO and PVYNTN. To understand the mechanism of this transmission bias as well as preferential virus binding, we separated virus and active helper component proteins (HC), mixed them in homologous and heterologous combinations, and then fed them to aphids using Parafilm sachets. Mixtures of PVYO HC with either PVYN:O or PVYNTN resulted in efficient transmission. PVYN:O HC also facilitated the transmission of PVYO and PVYNTN, albeit with reduced efficiency. PVYNTN HC failed to facilitate transmission of either PVYO or PVYN:O. When PVYO HC or PVYN:O HC was mixed with equal amounts of the two viruses, both viruses in all combinations were transmitted at high efficiencies. In contrast, no transmission occurred when combinations of viruses were mixed with PVYNTN HC. Further study evaluated transmission using serial dilutions of purified virus mixed with HCs. While PVYNTN HC only facilitated the transmission of the homologous virus, the HCs of PVYO and PVYN:O facilitated the transmission of all strains tested. This phenomenon has likely contributed to the increase in the recombinant strains affecting the USA potato crop.
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Affiliation(s)
- Shaonpius Mondal
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853-5904, USA
- Present address: USDA-ARS, Crop Improvement and Protection Research Unit, CA 93905, Salinas, USA
| | | | - Stewart M Gray
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853-5904, USA
- USDA-ARS, Emerging Pests and Pathogen Research Unit, Ithaca, NY 14853-5904, USA
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Differences in Virulence among PVY Isolates of Different Geographical Origins When Infecting an Experimental Host under Two Growing Environments Are Not Determined by HCPro. PLANTS 2021; 10:plants10061086. [PMID: 34071353 PMCID: PMC8228399 DOI: 10.3390/plants10061086] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/24/2021] [Accepted: 05/26/2021] [Indexed: 12/29/2022]
Abstract
The contribution of the HCPro factors expressed by several PVY isolates of different geographical origins (one from Scotland, one from Spain, and several from Tunisia) to differences in their virulence in Nicotiana benthamiana plants was investigated under two growing conditions: standard (st; 26 °C and current ambient levels of CO2), and climate change-associated (cc; 31 °C and elevated levels of CO2). In all cases, relative infection symptoms and viral titers were determined. The viral HCPro cistrons were also sequenced and amino-acid features of the encoded proteins were established, as well as phylogenetic distances. Additionally, the abilities of the HCPros of several isolates to suppress silencing were assessed under either growing condition. Overall, viral titers and infection symptoms decreased under cc vs. st conditions. However, within each growing condition, relative titers and symptoms were found to be isolate-specific, with titers and symptom severities not always correlating. Crucially, isolates expressing identical HCPros displayed different symptoms. In addition, all HCPro variants tested displayed comparable silencing suppression strengths. Therefore, HCPro alone could not be the main determinant of the relative differences in pathogenicity observed among the PVY isolates tested in this host, under the environments considered.
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Dubiella U, Serrano I. The Ubiquitin Proteasome System as a Double Agent in Plant-Virus Interactions. PLANTS (BASEL, SWITZERLAND) 2021; 10:plants10050928. [PMID: 34066628 PMCID: PMC8148538 DOI: 10.3390/plants10050928] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/30/2021] [Accepted: 05/05/2021] [Indexed: 05/03/2023]
Abstract
The ubiquitin proteasome is a rapid, adaptive mechanism for selective protein degradation, crucial for proper plant growth and development. The ubiquitin proteasome system (UPS) has also been shown to be an integral part of plant responses to stresses, including plant defence against pathogens. Recently, significant progress has been made in the understanding of the involvement of the UPS in the signalling and regulation of the interaction between plants and viruses. This review aims to discuss the current knowledge about the response of plant viral infection by the UPS and how the viruses counteract this system, or even use it for their own benefit.
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Affiliation(s)
- Ullrich Dubiella
- KWS SAAT SE & Co. KGaA, Grimsehlstraße 31, 37574 Einbeck, Germany;
| | - Irene Serrano
- Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, 37077 Göttingen, Germany
- Correspondence:
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Rajarapu SP, Ullman DE, Uzest M, Rotenberg D, Ordaz NA, Whitfield AE. Plant–Virus–Vector Interactions. Virology 2021. [DOI: 10.1002/9781119818526.ch7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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69
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Domingo-Calap ML, Chase O, Estapé M, Moreno AB, López-Moya JJ. The P1 Protein of Watermelon mosaic virus Compromises the Activity as RNA Silencing Suppressor of the P25 Protein of Cucurbit yellow stunting disorder virus. Front Microbiol 2021; 12:645530. [PMID: 33828542 PMCID: PMC8019732 DOI: 10.3389/fmicb.2021.645530] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 03/02/2021] [Indexed: 11/17/2022] Open
Abstract
Mixed viral infections in plants involving a potyvirus and other unrelated virus often result in synergistic effects, with significant increases in accumulation of the non-potyvirus partner, as in the case of melon plants infected by the potyvirus Watermelon mosaic virus (WMV) and the crinivirus Cucurbit yellow stunting disorder virus (CYSDV). To further explore the synergistic interaction between these two viruses, the activity of RNA silencing suppressors (RSSs) was addressed in transiently co-expressed combinations of heterologous viral products in Nicotiana benthamiana leaves. While the strong RSS activity of WMV Helper Component Proteinase (HCPro) was unaltered, including no evident additive effects observed when co-expressed with the weaker CYSDV P25, an unexpected negative effect of WMV P1 was found on the RSS activity of P25. Analysis of protein expression during the assays showed that the amount of P25 was not reduced when co-expressed with P1. The detrimental action of P1 on the activity of P25 was dose-dependent, and the subcellular localization of fluorescently labeled variants of P1 and P25 when transiently co-expressed showed coincidences both in nucleus and cytoplasm. Also, immunoprecipitation experiments showed interaction of tagged versions of the two proteins. This novel interaction, not previously described in other combinations of potyviruses and criniviruses, might play a role in modulating the complexities of the response to multiple viral infections in susceptible plants.
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Affiliation(s)
- Maria Luisa Domingo-Calap
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB Bellaterra, Barcelona, Spain.,Instituto Valencia de Investigaciones Agrarias, IVIA, Valencia, Spain
| | - Ornela Chase
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB Bellaterra, Barcelona, Spain
| | - Mariona Estapé
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB Bellaterra, Barcelona, Spain.,Universitair Medisch Centrum, UMC, Utrecht, Netherlands
| | - Ana Beatriz Moreno
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB Bellaterra, Barcelona, Spain
| | - Juan José López-Moya
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB Bellaterra, Barcelona, Spain.,Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain
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70
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Wang A. Cell-to-cell movement of plant viruses via plasmodesmata: a current perspective on potyviruses. Curr Opin Virol 2021; 48:10-16. [PMID: 33784579 DOI: 10.1016/j.coviro.2021.03.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 02/24/2021] [Accepted: 03/03/2021] [Indexed: 01/18/2023]
Abstract
Plant viruses have evolved efficient mechanisms to move cell-to-cell through plasmodesmata (PD) for systemic infection. Potyviruses including many economically important viruses constitute the largest group of known plant-infecting RNA viruses. Potyviral intercellular movement is accomplished by the coordinated action of at least three viral proteins and diverse host components. It requires the viral coat protein and is interlinked with active virus replication that generates, through RNA-polymerase slippage, a small percentage of frameshift viral RNA for the production of another essential movement protein named P3N-PIPO. This PD-located protein targets the virus-encoded cylindrical inclusion protein to PD to form special conical structures for potyviral passage, possibly in the form of virion. Here, I highlight and discuss major advances of potyviral intercellular trafficking.
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Affiliation(s)
- Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford Street, London, Ontario, N5V 4T3, Canada.
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71
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De Moya-Ruiz C, Rabadán P, Juárez M, Gómez P. Assessment of the Current Status of Potyviruses in Watermelon and Pumpkin Crops in Spain: Epidemiological Impact of Cultivated Plants and Mixed Infections. PLANTS (BASEL, SWITZERLAND) 2021; 10:138. [PMID: 33445406 PMCID: PMC7827711 DOI: 10.3390/plants10010138] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 01/04/2021] [Accepted: 01/06/2021] [Indexed: 12/17/2022]
Abstract
Viral infections on cucurbit plants cause substantial quality and yield losses on their crops. The diseased plants can often be infected by multiple viruses, and their epidemiology may depend, in addition to the agro-ecological management practices, on the combination of these viral infections. Watermelon mosaic virus (WMV) is one of the most prevalent viruses in cucurbit crops, and Moroccan watermelon mosaic virus (MWMV) emerged as a related species that threatens these crops. The occurrence of WMV and MWMV was monitored in a total of 196 apical-leaf samples of watermelon and pumpkin plants that displayed mosaic symptoms. The samples were collected from 49 fields in three major cucurbit-producing areas in Spain (Castilla La-Mancha, Alicante, and Murcia) for three consecutive (2018-2020) seasons. A molecular hybridization dot-blot method revealed that WMV was mainly (53%) found in both cultivated plants, with an unadvertised occurrence of MWMV. To determine the extent of cultivated plant species and mixed infections on viral dynamics, two infectious cDNA clones were constructed from a WMV isolate (MeWM7), and an MWMV isolate (ZuM10). Based on the full-length genomes, both isolates were grouped phylogenetically with the Emergent and European clades, respectively. Five-cucurbit plant species were infected steadily with either WMV or MWMV cDNA clones, showing variations on symptom expressions. Furthermore, the viral load varied depending on the plant species and infection type. In single infections, the WMV isolate showed a higher viral load than the MWMV isolate in melon and pumpkin, and MWMV only showed higher viral load than the WMV isolate in zucchini plants. However, in mixed infections, the viral load of the WMV isolate was greater than MWMV isolate in melon, watermelon and zucchini, whereas MWMV isolate was markedly reduced in zucchini. These results suggest that the impaired distribution of MWMV in cucurbit crops may be due to the cultivated plant species, in addition to the high prevalence of WMV.
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Affiliation(s)
- Celia De Moya-Ruiz
- Centro de Edafología y Biología Aplicada del Segura (CEBAS)—CSIC, Departamento de Biología del Estrés y Patología Vegetal, P.O. Box 164, 30100 Murcia, Spain; (C.D.M.-R.); (P.R.)
| | - Pilar Rabadán
- Centro de Edafología y Biología Aplicada del Segura (CEBAS)—CSIC, Departamento de Biología del Estrés y Patología Vegetal, P.O. Box 164, 30100 Murcia, Spain; (C.D.M.-R.); (P.R.)
| | - Miguel Juárez
- Escuela Politécnica Superior de Orihuela, Universidad Miguel Hernández de Elche, Orihuela, 03312 Alicante, Spain;
| | - Pedro Gómez
- Centro de Edafología y Biología Aplicada del Segura (CEBAS)—CSIC, Departamento de Biología del Estrés y Patología Vegetal, P.O. Box 164, 30100 Murcia, Spain; (C.D.M.-R.); (P.R.)
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72
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Chen AYS, Peng JHC, Polek M, Tian T, Ludman M, Fátyol K, Ng JCK. Comparative analysis identifies amino acids critical for citrus tristeza virus (T36CA) encoded proteins involved in suppression of RNA silencing and differential systemic infection in two plant species. MOLECULAR PLANT PATHOLOGY 2021; 22:64-76. [PMID: 33118689 PMCID: PMC7749750 DOI: 10.1111/mpp.13008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/05/2020] [Accepted: 09/22/2020] [Indexed: 05/06/2023]
Abstract
Complementary (c)DNA clones corresponding to the full-length genome of T36CA (a Californian isolate of Citrus tristeza virus with the T36 genotype), which shares 99.1% identity with that of T36FL (a T36 isolate from Florida), were made into a vector system to express the green fluorescent protein (GFP). Agroinfiltration of two prototype T36CA-based vectors (pT36CA) to Nicotiana benthamiana plants resulted in local but not systemic GFP expression/viral infection. This contrasted with agroinfiltration of the T36FL-based vector (pT36FL), which resulted in both local and systemic GFP expression/viral infection. A prototype T36CA systemically infected RNA silencing-defective N. benthamiana lines, demonstrating that a genetic basis for its defective systemic infection was RNA silencing. We evaluated the in planta bioactivity of chimeric pT36CA-pT36FL constructs and the results suggested that nucleotide variants in several open reading frames of the prototype T36CA could be responsible for its defective systemic infection. A single amino acid substitution in each of two silencing suppressors, p20 (S107G) and p25 (G36D), of prototype T36CA facilitated its systemic infectivity in N. benthamiana (albeit with reduced titre relative to that of T36FL) but not in Citrus macrophylla plants. Enhanced virus accumulation and, remarkably, robust systemic infection of T36CA in N. benthamiana and C. macrophylla plants, respectively, required two additional amino acid substitutions engineered in p65 (N118S and S158L), a putative closterovirus movement protein. The availability of pT36CA provides a unique opportunity for comparative analysis to identify viral coding and noncoding nucleotides or sequences involved in functions that are vital for in planta infection.
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Affiliation(s)
- Angel Y. S. Chen
- Department of Microbiology and Plant PathologyUniversity of CaliforniaRiversideCaliforniaUSA
| | - James H. C. Peng
- Department of Microbiology and Plant PathologyUniversity of CaliforniaRiversideCaliforniaUSA
| | - MaryLou Polek
- National Clonal Germplasm Repository for Citrus & DatesUSDA ARSRiversideCaliforniaUSA
| | - Tongyan Tian
- California Department of Food and AgricultureSacramentoCaliforniaUSA
| | - Márta Ludman
- Agricultural Biotechnology InstituteNational Research and Innovation CenterHungary
| | - Károly Fátyol
- Agricultural Biotechnology InstituteNational Research and Innovation CenterHungary
| | - James C. K. Ng
- Department of Microbiology and Plant PathologyUniversity of CaliforniaRiversideCaliforniaUSA
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A Newly Identified Virus in the Family Potyviridae Encodes Two Leader Cysteine Proteases in Tandem That Evolved Contrasting RNA Silencing Suppression Functions. J Virol 2020; 95:JVI.01414-20. [PMID: 33055249 DOI: 10.1128/jvi.01414-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 10/05/2020] [Indexed: 02/06/2023] Open
Abstract
Potyviridae is the largest family of plant-infecting RNA viruses and includes many agriculturally and economically important viral pathogens. The viruses in the family, known as potyvirids, possess single-stranded, positive-sense RNA genomes with polyprotein processing as a gene expression strategy. The N-terminal regions of potyvirid polyproteins vary greatly in sequence. Previously, we identified a novel virus species within the family, Areca palm necrotic spindle-spot virus (ANSSV), which was predicted to encode two cysteine proteases, HCPro1 and HCPro2, in tandem at the N-terminal region. Here, we present evidence showing self-cleavage activity of these two proteins and define their cis-cleavage sites. We demonstrate that HCPro2 is a viral suppressor of RNA silencing (VSR), and both the variable N-terminal and conserved C-terminal (protease domain) moieties have antisilencing activity. Intriguingly, the N-terminal region of HCPro1 also has RNA silencing suppression activity, which is, however, suppressed by its C-terminal protease domain, leading to the functional divergence of HCPro1 and HCPro2 in RNA silencing suppression. Moreover, the deletion of HCPro1 or HCPro2 in a newly created infectious clone abolishes viral infection, and the deletion mutants cannot be rescued by addition of corresponding counterparts of a potyvirus. Altogether, these data suggest that the two closely related leader proteases of ANSSV have evolved differential and essential functions to concertedly maintain viral viability.IMPORTANCE The Potyviridae represent the largest group of known plant RNA viruses and account for more than half of the viral crop damage worldwide. The leader proteases of viruses within the family vary greatly in size and arrangement and play key roles during the infection. Here, we experimentally demonstrate the presence of a distinct pattern of leader proteases, HCPro1 and HCPro2 in tandem, in a newly identified member within the family. Moreover, HCPro1 and HCPro2, which are closely related and typically characterized with a short size, have evolved contrasting RNA silencing suppression activity and seem to function in a coordinated manner to maintain viral infectivity. Altogether, the new knowledge fills a missing piece in the evolutionary relationship history of potyvirids and improves our understanding of the diversification of potyvirid genomes.
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74
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Marwal A, Gaur RK. Host Plant Strategies to Combat Against Viruses Effector Proteins. Curr Genomics 2020; 21:401-410. [PMID: 33093803 PMCID: PMC7536791 DOI: 10.2174/1389202921999200712135131] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 06/17/2020] [Accepted: 06/19/2020] [Indexed: 02/02/2023] Open
Abstract
Viruses are obligate parasites that exist in an inactive state until they enter the host body. Upon entry, viruses become active and start replicating by using the host cell machinery. All plant viruses can augment their transmission, thus powering their detrimental effects on the host plant. To diminish infection and diseases caused by viruses, the plant has a defence mechanism known as pathogenesis-related biochemicals, which are metabolites and proteins. Proteins that ultimately prevent pathogenic diseases are called R proteins. Several plant R genes (that confirm resistance) and avirulence protein (Avr) (pathogen Avr gene-encoded proteins [effector/elicitor proteins involved in pathogenicity]) molecules have been identified. The recognition of such a factor results in the plant defence mechanism. During plant viral infection, the replication and expression of a viral molecule lead to a series of a hypersensitive response (HR) and affect the host plant's immunity (pathogen-associated molecular pattern-triggered immunity and effector-triggered immunity). Avr protein renders the host RNA silencing mechanism and its innate immunity, chiefly known as silencing suppressors towards the plant defensive machinery. This is a strong reply to the plant defensive machinery by harmful plant viruses. In this review, we describe the plant pathogen resistance protein and how these proteins regulate host immunity during plant-virus interactions. Furthermore, we have discussed regarding ribosome-inactivating proteins, ubiquitin proteasome system, translation repression (nuclear shuttle protein interacting kinase 1), DNA methylation, dominant resistance genes, and autophagy-mediated protein degradation, which are crucial in antiviral defences.
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Affiliation(s)
- Avinash Marwal
- 1Department of Biotechnology, Vigyan Bhawan - Block B, New Campus, Mohanlal Sukhadia University, Udaipur, Rajasthan - 313001, India; 2Department of Biotechnology, Deen Dayal Upadhyay Gorakhpur University, Gorakhpur, Uttar Pradesh - 273009, India
| | - Rajarshi Kumar Gaur
- 1Department of Biotechnology, Vigyan Bhawan - Block B, New Campus, Mohanlal Sukhadia University, Udaipur, Rajasthan - 313001, India; 2Department of Biotechnology, Deen Dayal Upadhyay Gorakhpur University, Gorakhpur, Uttar Pradesh - 273009, India
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75
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Freire MÁ. Viral silencing suppressors and cellular proteins partner with plant RRP6-like exoribonucleases. Virus Genes 2020; 56:621-631. [PMID: 32519287 DOI: 10.1007/s11262-020-01775-z] [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: 02/20/2020] [Accepted: 06/02/2020] [Indexed: 10/24/2022]
Abstract
RNA silencing and RNA decay are functionally interlaced, regulate gene expression and play a pivotal role in antiviral responses. As a counter-defensive strategy, many plant and mammalian viruses encode suppressors which interfere with both mechanisms. However, the protein interactions that connect these pathways remain elusive. Previous work reported that RNA silencing suppressors from different potyviruses, together with translation initiation factors EIF(iso)4E, interacted with the C-terminal region of the tobacco exoribonuclease RRP6-like 2, a component of the RNA decay exosome complex. Here, we investigate whether other viral silencing suppressors and cellular proteins might also bind RRP6-like exoribonucleases. A candidate search approach based on yeast two-hybrid protein interaction assays showed that three other unrelated viral suppressors, two from plant viruses and one from a mammalian virus, bound the C-terminus of the tobacco RRP6-like 2, the full-length of the Arabidopsis RRP6L1 protein and its C-terminal region. In addition, RRP6-like proteins were found to interact with members of the cellular double-stranded RNA-binding protein (DRB) family involved in RNA silencing. The C-terminal regions of RRP6L proteins are engaged in homotypic and heterotypic interactions and were predicted to be disordered. Collectively, these results suggest a protein interaction network that connects components of RNA decay and RNA silencing that is targeted by viral silencing suppressors.
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Affiliation(s)
- Miguel Ángel Freire
- Instituto Multidisciplinario de Biología Vegetal (IMBIV), CONICET, Universidad Nacional de Córdoba (UNC), Av. Vélez Sarsfield 299, CC 495, 5000, Córdoba, Argentina.
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De S, Pollari M, Varjosalo M, Mäkinen K. Association of host protein VARICOSE with HCPro within a multiprotein complex is crucial for RNA silencing suppression, translation, encapsidation and systemic spread of potato virus A infection. PLoS Pathog 2020; 16:e1008956. [PMID: 33045020 PMCID: PMC7581364 DOI: 10.1371/journal.ppat.1008956] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 10/22/2020] [Accepted: 09/02/2020] [Indexed: 12/17/2022] Open
Abstract
In this study, we investigated the significance of a conserved five-amino acid motif 'AELPR' in the C-terminal region of helper component-proteinase (HCPro) for potato virus A (PVA; genus Potyvirus) infection. This motif is a putative interaction site for WD40 domain-containing proteins, including VARICOSE (VCS). We abolished the interaction site in HCPro by replacing glutamic acid (E) and arginine (R) with alanines (A) to generate HCProWD. These mutations partially eliminated HCPro-VCS co-localization in cells. We have earlier described potyvirus-induced RNA granules (PGs) in which HCPro and VCS co-localize and proposed that they have a role in RNA silencing suppression. We now demonstrate that the ability of HCProWD to induce PGs, introduce VCS into PGs, and suppress RNA silencing was impaired. Accordingly, PVA carrying HCProWD (PVAWD) infected Nicotiana benthamiana less efficiently than wild-type PVA (PVAWT) and HCProWD complemented the lack of HCPro in PVA gene expression only partially. HCPro was purified from PVA-infected leaves as part of high molecular weight (HMW) ribonucleoprotein (RNP) complexes. These complexes were more stable when associated with wild-type HCPro than with HCProWD. Moreover, VCS and two viral components of the HMW-complexes, viral protein genome-linked and cylindrical inclusion protein were specifically decreased in HCProWD-containing HMW-complexes. A VPg-mediated boost in translation of replication-deficient PVA (PVAΔGDD) was observed only if viral RNA expressed wild-type HCPro. The role of VCS-VPg-HCPro coordination in PVA translation was further supported by results from VCS silencing and overexpression experiments and by significantly elevated PVA-derived Renilla luciferase vs PVA RNA ratio upon VPg-VCS co-expression. Finally, we found that PVAWD was unable to form virus particles or to spread systemically in the infected plant. We highlight the role of HCPro-VCS containing multiprotein assemblies associated with PVA RNA in protecting it from degradation, ensuring efficient translation, formation of stable virions and establishment of systemic infection.
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Affiliation(s)
- Swarnalok De
- University of Helsinki, Department of Microbiology and Viikki Plant Science Centre, Finland
| | - Maija Pollari
- University of Helsinki, Department of Microbiology and Viikki Plant Science Centre, Finland
| | | | - Kristiina Mäkinen
- University of Helsinki, Department of Microbiology and Viikki Plant Science Centre, Finland
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Pollari M, De S, Wang A, Mäkinen K. The potyviral silencing suppressor HCPro recruits and employs host ARGONAUTE1 in pro-viral functions. PLoS Pathog 2020; 16:e1008965. [PMID: 33031436 PMCID: PMC7575100 DOI: 10.1371/journal.ppat.1008965] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 10/20/2020] [Accepted: 09/04/2020] [Indexed: 11/19/2022] Open
Abstract
In this study, we demonstrate a novel pro-viral role for the Nicotiana benthamiana ARGONAUTE 1 (AGO1) in potyvirus infection. AGO1 strongly enhanced potato virus A (PVA) particle production and benefited the infection when supplied in excess. We subsequently identified the potyviral silencing suppressor, helper-component protease (HCPro), as the recruiter of host AGO1. After the identification of a conserved AGO1-binding GW/WG motif in potyviral HCPros, we used site-directed mutagenesis to introduce a tryptophan-to-alanine change into the HCPro (HCProAG) of PVA (PVAAG) and turnip mosaic virus (TuMVAG). AGO1 co-localization and co-immunoprecipitation with PVA HCPro was significantly reduced by the mutation suggesting the interaction was compromised. Although the mutation did not interfere with HCPro's complementation or silencing suppression capacity, it nevertheless impaired virus particle accumulation and the systemic spread of both PVA and TuMV. Furthermore, we found that the HCPro-AGO1 interaction was important for AGO1's association with the PVA coat protein. The coat protein was also more stable in wild type PVA infection than in PVAAG infection. Based on these findings we suggest that potyviral HCPro recruits host AGO1 through its WG motif and engages AGO1 in the production of stable virus particles, which are required for an efficient systemic infection.
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Affiliation(s)
- Maija Pollari
- University of Helsinki, Department of Microbiology, Viikki Plant Science Center, Helsinki, Finland
| | - Swarnalok De
- University of Helsinki, Department of Microbiology, Viikki Plant Science Center, Helsinki, Finland
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
| | - Kristiina Mäkinen
- University of Helsinki, Department of Microbiology, Viikki Plant Science Center, Helsinki, Finland
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78
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Morozov SY, Solovyev AG. Small hydrophobic viral proteins involved in intercellular movement of diverse plant virus genomes. AIMS Microbiol 2020; 6:305-329. [PMID: 33134746 PMCID: PMC7595835 DOI: 10.3934/microbiol.2020019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 09/13/2020] [Indexed: 12/12/2022] Open
Abstract
Most plant viruses code for movement proteins (MPs) targeting plasmodesmata to enable cell-to-cell and systemic spread in infected plants. Small membrane-embedded MPs have been first identified in two viral transport gene modules, triple gene block (TGB) coding for an RNA-binding helicase TGB1 and two small hydrophobic proteins TGB2 and TGB3 and double gene block (DGB) encoding two small polypeptides representing an RNA-binding protein and a membrane protein. These findings indicated that movement gene modules composed of two or more cistrons may encode the nucleic acid-binding protein and at least one membrane-bound movement protein. The same rule was revealed for small DNA-containing plant viruses, namely, viruses belonging to genus Mastrevirus (family Geminiviridae) and the family Nanoviridae. In multi-component transport modules the nucleic acid-binding MP can be viral capsid protein(s), as in RNA-containing viruses of the families Closteroviridae and Potyviridae. However, membrane proteins are always found among MPs of these multicomponent viral transport systems. Moreover, it was found that small membrane MPs encoded by many viruses can be involved in coupling viral replication and cell-to-cell movement. Currently, the studies of evolutionary origin and functioning of small membrane MPs is regarded as an important pre-requisite for understanding of the evolution of the existing plant virus transport systems. This paper represents the first comprehensive review which describes the whole diversity of small membrane MPs and presents the current views on their role in plant virus movement.
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Affiliation(s)
- Sergey Y Morozov
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia.,Department of Virology, Biological Faculty, Moscow State University, Moscow, Russia
| | - Andrey G Solovyev
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia.,Department of Virology, Biological Faculty, Moscow State University, Moscow, Russia.,Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, Russia
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79
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Yang T, Qiu L, Huang W, Xu Q, Zou J, Peng Q, Lin H, Xi D. Chilli veinal mottle virus HCPro interacts with catalase to facilitate virus infection in Nicotiana tabacum. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:5656-5668. [PMID: 32594157 PMCID: PMC7501817 DOI: 10.1093/jxb/eraa304] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 06/19/2020] [Indexed: 05/06/2023]
Abstract
Plant symptoms are derived from specific interactions between virus and host components. However, little is known about viral or host factors that participate in the establishment of systemic necrosis. Here, we showed that helper component proteinase (HCPro), encoded by Chilli veinal mottle virus (ChiVMV), could directly interact with catalase 1 (CAT1) and catalase 3 (CAT3) in the cytoplasm of tobacco (Nicotiana tabacum) plants to facilitate viral infection. In vitro, the activities of CAT1 and CAT3 were inhibited by the interaction between HCPro and CATs. The C-terminus of HCPro was essential for their interaction and was also required for the decrease of enzyme activities. Interestingly, the mRNA and protein level of CATs were up-regulated in tobacco plants in response to ChiVMV infection. Nicotiana tabacum plants with HCPro overexpression or CAT1 knockout were more susceptible to ChiVMV infection, which was similar to the case of H2O2-pre-treated plants, and the overexpression of CAT1 inhibited ChiVMV accumulation. Also, neither CAT1 nor CAT3 could affect the RNA silencing suppression (RSS) activity of HCPro. Our results showed that the interaction between HCPro and CATs promoted the development of plant systemic necrosis, revealing a novel role for HCPro in virus infection and pathogenicity.
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Affiliation(s)
- Ting Yang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan, PR China
| | - Long Qiu
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan, PR China
| | - Wanying Huang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan, PR China
| | - Qianyi Xu
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan, PR China
| | - Jialing Zou
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan, PR China
| | - Qiding Peng
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan, PR China
| | - Honghui Lin
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan, PR China
| | - Dehui Xi
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan, PR China
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80
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Sabharwal P, Savithri HS. Functional Characterization of Pepper Vein Banding Virus-Encoded Proteins and Their Interactions: Implications in Potyvirus Infection. Viruses 2020; 12:v12091037. [PMID: 32957699 PMCID: PMC7551749 DOI: 10.3390/v12091037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 07/20/2020] [Accepted: 07/22/2020] [Indexed: 11/16/2022] Open
Abstract
Pepper vein banding virus (PVBV) is a distinct species in the Potyvirus genus which infects economically important plants in several parts of India. Like other potyviruses, PVBV encodes multifunctional proteins, with several interaction partners, having implications at different stages of the potyviral infection. In this review, we summarize the functional characterization of different PVBV-encoded proteins with an emphasis on their interaction partners governing the multifunctionality of potyviral proteins. Intrinsically disordered domains/regions of these proteins play an important role in their interactions with other proteins. Deciphering the function of PVBV-encoded proteins and their interactions with cognitive partners will help in understanding the putative mechanisms by which the potyviral proteins are regulated at different stages of the viral life-cycle. This review also discusses PVBV virus-like particles (VLPs) and their potential applications in nanotechnology. Further, virus-like nanoparticle-cell interactions and intracellular fate of PVBV VLPs are also discussed.
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81
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Pasin F, Shan H, García B, Müller M, San León D, Ludman M, Fresno DH, Fátyol K, Munné-Bosch S, Rodrigo G, García JA. Abscisic Acid Connects Phytohormone Signaling with RNA Metabolic Pathways and Promotes an Antiviral Response that Is Evaded by a Self-Controlled RNA Virus. PLANT COMMUNICATIONS 2020; 1:100099. [PMID: 32984814 PMCID: PMC7518510 DOI: 10.1016/j.xplc.2020.100099] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 07/03/2020] [Accepted: 07/07/2020] [Indexed: 05/13/2023]
Abstract
A complex network of cellular receptors, RNA targeting pathways, and small-molecule signaling provides robust plant immunity and tolerance to viruses. To maximize their fitness, viruses must evolve control mechanisms to balance host immune evasion and plant-damaging effects. The genus Potyvirus comprises plant viruses characterized by RNA genomes that encode large polyproteins led by the P1 protease. A P1 autoinhibitory domain controls polyprotein processing, the release of a downstream functional RNA-silencing suppressor, and viral replication. Here, we show that P1Pro, a plum pox virus clone that lacks the P1 autoinhibitory domain, triggers complex reprogramming of the host transcriptome and high levels of abscisic acid (ABA) accumulation. A meta-analysis highlighted ABA connections with host pathways known to control RNA stability, turnover, maturation, and translation. Transcriptomic changes triggered by P1Pro infection or ABA showed similarities in host RNA abundance and diversity. Genetic and hormone treatment assays showed that ABA promotes plant resistance to potyviral infection. Finally, quantitative mathematical modeling of viral replication in the presence of defense pathways supported self-control of polyprotein processing kinetics as a viral mechanism that attenuates the magnitude of the host antiviral response. Overall, our findings indicate that ABA is an active player in plant antiviral immunity, which is nonetheless evaded by a self-controlled RNA virus.
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Affiliation(s)
- Fabio Pasin
- Centro Nacional de Biotecnología (CNB-CSIC), 28049 Madrid, Spain
- Agricultural Biotechnology Research Center, Academia Sinica, 11529 Taipei, Taiwan
| | - Hongying Shan
- Centro Nacional de Biotecnología (CNB-CSIC), 28049 Madrid, Spain
| | - Beatriz García
- Centro Nacional de Biotecnología (CNB-CSIC), 28049 Madrid, Spain
| | - Maren Müller
- Departamento de Biología Evolutiva, Ecología y Ciencias Ambientales, Facultad de Biología, Universidad de Barcelona, 08028 Barcelona, Spain
| | - David San León
- Centro Nacional de Biotecnología (CNB-CSIC), 28049 Madrid, Spain
| | - Márta Ludman
- Agricultural Biotechnology Institute, National Agricultural Research and Innovation Centre, 2100 Gödöllő, Hungary
| | - David H. Fresno
- Departamento de Biología Evolutiva, Ecología y Ciencias Ambientales, Facultad de Biología, Universidad de Barcelona, 08028 Barcelona, Spain
| | - Károly Fátyol
- Agricultural Biotechnology Institute, National Agricultural Research and Innovation Centre, 2100 Gödöllő, Hungary
| | - Sergi Munné-Bosch
- Departamento de Biología Evolutiva, Ecología y Ciencias Ambientales, Facultad de Biología, Universidad de Barcelona, 08028 Barcelona, Spain
| | - Guillermo Rodrigo
- Institute for Integrative Systems Biology (I2SysBio), CSIC-University of Valencia, 46980 Paterna, Spain
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82
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Xu XJ, Li HG, Cheng DJ, Liu LZ, Geng C, Tian YP, Li XD. A Spontaneous Complementary Mutation Restores the RNA Silencing Suppression Activity of HC-Pro and the Virulence of Sugarcane Mosaic Virus. FRONTIERS IN PLANT SCIENCE 2020; 11:1279. [PMID: 32973838 PMCID: PMC7472499 DOI: 10.3389/fpls.2020.01279] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 08/05/2020] [Indexed: 05/26/2023]
Abstract
Cross-protection is a promising measure to control plant viral diseases. Reverse genetics had been recently adopted to generate attenuated mutants that have potential in cross-protection. But studies on the variability of the progeny viruses of the attenuated mutants are scarce. Sugarcane mosaic virus (SCMV; genus Potyvirus, family Potyviridae) is the prevalent virus inducing maize dwarf mosaic disease in China. Here, we showed that the substitution of arginine with isoleucine in the FRNK motif at position 184 of helper component-proteinase (HC-Pro) abolished its RNA silencing suppression (RSS) activity, drastically reduced the virulence and accumulation level of SCMV, and impaired the synergism between SCMV and maize chlorotic mottle virus. The attenuated mutant could protect maize plants from a severe infection of SCMV. However, a spontaneous mutation of glycine at position 440 to arginine in HC-Pro rescued the virulence and synergism with maize chlorotic mottle virus of SCMV and the RSS activity of HC-Pro. Similar results were obtained with tobacco vein banding mosaic virus and watermelon mosaic virus. These results provide novel evidence for the complementary mutation of potyviruses in maintaining the HC-Pro RSS activity and potyviral virulence and remind us of evaluating the potential risk of attenuated mutants thoroughly before applying for the control of plant viral diseases via cross-protection.
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Affiliation(s)
- Xiao-Jie Xu
- Shandong Province Key Laboratory for Agricultural Microbiology, Laboratory of Plant Virology, Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University, Tai’an, China
| | - Huan-Gai Li
- Protein Science Laboratory of Ministry of Education, School of Life Sciences, Tsinghua University, Beijing, China
| | - De-Jie Cheng
- Shandong Province Key Laboratory for Agricultural Microbiology, Laboratory of Plant Virology, Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University, Tai’an, China
| | - Ling-Zhi Liu
- Shandong Province Key Laboratory for Agricultural Microbiology, Laboratory of Plant Virology, Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University, Tai’an, China
| | - Chao Geng
- Shandong Province Key Laboratory for Agricultural Microbiology, Laboratory of Plant Virology, Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University, Tai’an, China
| | - Yan-Ping Tian
- Shandong Province Key Laboratory for Agricultural Microbiology, Laboratory of Plant Virology, Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University, Tai’an, China
| | - Xiang-Dong Li
- Shandong Province Key Laboratory for Agricultural Microbiology, Laboratory of Plant Virology, Department of Plant Pathology, College of Plant Protection, Shandong Agricultural University, Tai’an, China
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83
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Sanfaçon H. Modulation of disease severity by plant positive-strand RNA viruses: The complex interplay of multifunctional viral proteins, subviral RNAs and virus-associated RNAs with plant signaling pathways and defense responses. Adv Virus Res 2020; 107:87-131. [PMID: 32711736 DOI: 10.1016/bs.aivir.2020.04.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Plant viruses induce a range of symptoms of varying intensity, ranging from severe systemic necrosis to mild or asymptomatic infection. Several evolutionary constraints drive virus virulence, including the dependence of viruses on host factors to complete their infection cycle, the requirement to counteract or evade plant antiviral defense responses and the mode of virus transmission. Viruses have developed an array of strategies to modulate disease severity. Accumulating evidence has highlighted not only the multifunctional role that viral proteins play in disrupting or highjacking plant factors, hormone signaling pathways and intracellular organelles, but also the interaction networks between viral proteins, subviral RNAs and/or other viral-associated RNAs that regulate disease severity. This review focusses on positive-strand RNA viruses, which constitute the majority of characterized plant viruses. Using well-characterized viruses with different genome types as examples, recent advances are discussed as well as knowledge gaps and opportunities for further research.
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Affiliation(s)
- Hélène Sanfaçon
- Summerland Research and Development Centre, Agriculture and Agri-Food Canada, Summerland, BC, Canada.
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84
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Aphid Transmission of Potyvirus: The Largest Plant-Infecting RNA Virus Genus. Viruses 2020; 12:v12070773. [PMID: 32708998 PMCID: PMC7411817 DOI: 10.3390/v12070773] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/12/2020] [Accepted: 07/15/2020] [Indexed: 12/15/2022] Open
Abstract
Potyviruses are the largest group of plant infecting RNA viruses that cause significant losses in a wide range of crops across the globe. The majority of viruses in the genus Potyvirus are transmitted by aphids in a non-persistent, non-circulative manner and have been extensively studied vis-à-vis their structure, taxonomy, evolution, diagnosis, transmission, and molecular interactions with hosts. This comprehensive review exclusively discusses potyviruses and their transmission by aphid vectors, specifically in the light of several virus, aphid and plant factors, and how their interplay influences potyviral binding in aphids, aphid behavior and fitness, host plant biochemistry, virus epidemics, and transmission bottlenecks. We present the heatmap of the global distribution of potyvirus species, variation in the potyviral coat protein gene, and top aphid vectors of potyviruses. Lastly, we examine how the fundamental understanding of these multi-partite interactions through multi-omics approaches is already contributing to, and can have future implications for, devising effective and sustainable management strategies against aphid-transmitted potyviruses to global agriculture.
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85
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Jiang Z, Zhang K, Li Z, Li Z, Yang M, Jin X, Cao Q, Wang X, Yue N, Li D, Zhang Y. The Barley stripe mosaic virus γb protein promotes viral cell-to-cell movement by enhancing ATPase-mediated assembly of ribonucleoprotein movement complexes. PLoS Pathog 2020; 16:e1008709. [PMID: 32730331 PMCID: PMC7419011 DOI: 10.1371/journal.ppat.1008709] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 08/11/2020] [Accepted: 06/17/2020] [Indexed: 02/07/2023] Open
Abstract
Nine genera of viruses in five different families use triple gene block (TGB) proteins for virus movement. The TGB modules fall into two classes: hordei-like and potex-like. Although TGB-mediated viral movement has been extensively studied, determination of the constituents of the viral ribonucleoprotein (vRNP) movement complexes and the mechanisms underlying their involvement in vRNP-mediated movement are far from complete. In the current study, immunoprecipitation of TGB1 protein complexes formed during Barley stripe mosaic virus (BSMV) infection revealed the presence of the γb protein in the products. Further experiments demonstrated that TGB1 interacts with γb in vitro and in vivo, and that γb-TGB1 localizes at the periphery of chloroplasts and plasmodesmata (PD). Subcellular localization analyses of the γb protein in Nicotiana benthamiana epidermal cells indicated that in addition to chloroplast localization, γb also targets the ER, actin filaments and PD at different stages of viral infection. By tracking γb localization during BSMV infection, we demonstrated that γb is required for efficient cell-to-cell movement. The N-terminus of γb interacts with the TGB1 ATPase/helicase domain and enhances ATPase activity of the domain. Inactivation of the TGB1 ATPase activity also significantly impaired PD targeting. In vitro translation together with co-immunoprecipitation (co-IP) analyses revealed that TGB1-TGB3-TGB2 complex formation is enhanced by ATP hydrolysis. The γb protein positively regulates complex formation in the presence of ATP, suggesting that γb has a novel role in BSMV cell-to-cell movement by directly promoting TGB1 ATPase-mediated vRNP movement complex assembly. We further demonstrated that elimination of ATPase activity abrogates PD and actin targeting of Potato virus X (PVX) and Beet necrotic yellow vein virus (BNYVV) TGB1 proteins. These results expand our understanding of the multifunctional roles of γb and provide new insight into the functions of TGB1 ATPase domains in the movement of TGB-encoding viruses.
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Affiliation(s)
- Zhihao Jiang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Kun Zhang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Zhaolei Li
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Zhenggang Li
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Meng Yang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Xuejiao Jin
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Qing Cao
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Xueting Wang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Ning Yue
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Dawei Li
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
| | - Yongliang Zhang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P. R. China
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86
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Efficient silencing gene construct for resistance to multiple common bean ( Phaseolus vulgaris L.) viruses. 3 Biotech 2020; 10:278. [PMID: 32537378 DOI: 10.1007/s13205-020-02276-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 05/25/2020] [Indexed: 12/16/2022] Open
Abstract
One promising strategy to engineer plants that are resistant to plant pathogens involves transforming plants with RNA silencing constructs for resistance to multiple pathogens. Garden bean is significantly damaged by bean common mosaic virus (BCMV), bean common mosaic necrosis virus (BCMNV) and cucumber mosaic virus (CMV). In this study, we prepared constructs producing sense, antisense and hairpin RNA (hpRNA) structures to target single as well as multiple viruses. Silencing efficiency of these constructions was analyzed using Agrobacterium (GV3101) transient expression in Nicothinia bethamiana and Phaseolus vulgaris plants. The results showed significantly reduced disease symptoms and virus accumulation in N. bethamiana plants. Generally, the efficiency of the prepared constructs was hairpin, antisense and sense, respectively, and also, there was a significant difference between mono-gene and multiple-gene constructs for reducng virus accumulation and the multiple-gene constructs showed higher effectiveness. Experiments in this study showed that using Agrobacterium harboring binary constructs containing a Caenorhabditis elegans gene, Ced-9, or a plant gene, AtBag-4, anti-apoptosis gene as a mix suspension with an Agrobacterium containing pFGC-BNC.h, a plasmid containing multiple gene fragments consisting of BCMV-CP, BCMNV-HC-Pro and CMV-2b, improved the efficiency of pFGC-BNC.h transformation. We showed reduced virus accumulation in these transgenic bean plans.
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87
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Yang L, Meng D, Wang Y, Wu Y, Lang C, Jin T, Zhou X. The viral suppressor HCPro decreases DNA methylation and activates auxin biosynthesis genes. Virology 2020; 546:133-140. [PMID: 32452413 DOI: 10.1016/j.virol.2020.04.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 04/05/2020] [Accepted: 04/07/2020] [Indexed: 01/10/2023]
Abstract
Auxin has profound effects on plant growth and development. In addition to participating in plant growth and development, the auxin signaling pathway is involved in plant defense against pathogens. In this study, we investigated the molecular mechanism by which helper-component protease (HCPro) encoded by the Tobacco vein banding mosaic virus (TVBMV) activates auxin biosynthesis genes (YUCs) and interferes with the auxin signaling pathway. Our results demonstrated that the viral suppressor HCPro decreased the DNA methylation of dispersed repeats (DRs) within the promoters of YUC1, YUC5 and YUC10 and transcriptional activated these YUC genes targeted by RNA-directed DNA methylation (RdDM), leading to an increase in auxin accumulation in plants. Furthermore, we found that the induction of these YUCs by HCPro was attenuated in ros1 mutant plants, suggesting that HCPro-mediated transcriptional activation of the genes was partly dependent on ROS1-mediated DNA demethylation.
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Affiliation(s)
- Liping Yang
- The School of Life Sciences, Jilin Normal University, Siping, 136000, China.
| | - Dawei Meng
- The School of Life Sciences, Jilin Normal University, Siping, 136000, China.
| | - Yue Wang
- The School of Life Sciences, Jilin Normal University, Siping, 136000, China.
| | - Yanju Wu
- The School of Life Sciences, Jilin Normal University, Siping, 136000, China.
| | - Chenjing Lang
- The School of Life Sciences, Jilin Normal University, Siping, 136000, China
| | - Taicheng Jin
- The School of Life Sciences, Jilin Normal University, Siping, 136000, China.
| | - Xiaofu Zhou
- Key Laboratory for Plant Resources Science and Green Production, Jilin Normal University, Siping, 136000, China.
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88
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Hyodo K, Okuno T. Hijacking of host cellular components as proviral factors by plant-infecting viruses. Adv Virus Res 2020; 107:37-86. [PMID: 32711734 DOI: 10.1016/bs.aivir.2020.04.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Plant viruses are important pathogens that cause serious crop losses worldwide. They are obligate intracellular parasites that commandeer a wide array of proteins, as well as metabolic resources, from infected host cells. In the past two decades, our knowledge of plant-virus interactions at the molecular level has exploded, which provides insights into how plant-infecting viruses co-opt host cellular machineries to accomplish their infection. Here, we review recent advances in our understanding of how plant viruses divert cellular components from their original roles to proviral functions. One emerging theme is that plant viruses have versatile strategies that integrate a host factor that is normally engaged in plant defense against invading pathogens into a viral protein complex that facilitates viral infection. We also highlight viral manipulation of cellular key regulatory systems for successful virus infection: posttranslational protein modifications for fine control of viral and cellular protein dynamics; glycolysis and fermentation pathways to usurp host resources, and ion homeostasis to create a cellular environment that is beneficial for viral genome replication. A deeper understanding of viral-infection strategies will pave the way for the development of novel antiviral strategies.
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Affiliation(s)
- Kiwamu Hyodo
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, Japan.
| | - Tetsuro Okuno
- Department of Plant Life Science, Faculty of Agriculture, Ryukoku University, Otsu, Shiga, Japan
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89
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Zhang C, Chen D, Yang G, Yu X, Wu J. Rice Stripe Mosaic Virus-Encoded P4 Is a Weak Suppressor of Viral RNA Silencing and Is Required for Disease Symptom Development. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:412-422. [PMID: 31841359 DOI: 10.1094/mpmi-08-19-0239-ia] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Viral suppressors of RNA silencing (VSRs) are a cluster of viral proteins that have evolved to counteract eukaryotic antiviral RNA silencing pathways, thereby contributing to viral pathogenicity. In this study, we revealed that the matrix protein P4 encoded by rice stripe mosaic virus (RSMV), which is an emerging cytoplasmic rhabdovirus, is a weak RNA silencing suppressor. By conducting yeast two-hybrid, bimolecular fluorescence complementation, and subcellular colocalization assays, we proved that P4 interacts with the rice endogenous suppressor of gene silencing 3 (OsSGS3). We also determined that P4 overexpression has no effect on OsSGS3 transcription. However, P4 can promote the degradation of OsSGS3 via ubiquitination and autophagy. Additionally, a potato virus X-based expression system was used to confirm that P4 enhances the development of mosaic symptoms on Nicotiana benthamiana leaves by promoting hydrogen peroxide accumulation but not cell death. To verify whether P4 is a pathogenicity factor in host plants, we generated transgenic P4-overexpressing rice plants that exhibited disease-related developmental defects including decreased plant height and excessive tillering. Our data suggest that RSMV-encoded P4 serves as a weak VSR that inhibits antiviral RNA silencing by targeting OsSGS3.
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Affiliation(s)
- Chao Zhang
- Vector-borne Virus Research Center, State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Institute of Plant Virology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Dong Chen
- Vector-borne Virus Research Center, State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Institute of Plant Virology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Guoyi Yang
- Vector-borne Virus Research Center, State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Institute of Plant Virology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Xiyuan Yu
- Vector-borne Virus Research Center, State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Institute of Plant Virology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Jianguo Wu
- Vector-borne Virus Research Center, State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Institute of Plant Virology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
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90
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Isogai M, Matsudaira T, Miyoshi K, Shimura T, Torii S, Yoshikawa N. The raspberry bushy dwarf virus 1b gene enables pollen grains to function efficiently in horizontal pollen transmission. Virology 2020; 542:28-33. [PMID: 31957663 DOI: 10.1016/j.virol.2020.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 01/12/2020] [Accepted: 01/12/2020] [Indexed: 11/16/2022]
Abstract
Horizontal pollen transmission by the raspberry bushy dwarf virus 1b deletion mutant (RBΔ1bstop), which is defective in virus virulence, was significantly decreased compared to wild-type raspberry bushy dwarf virus (wtRBDV). We assessed accumulation of viral genomic (g) RNAs in pollen grains from RBΔ1bstop-infected plants and found that the pollen grains had less viral gRNA than those from wtRBDV-infected plants. In addition, pollen grains from 1b-expressing transgenic plants (1b-plants) infected with RBΔ1bstop were more efficient in horizontal virus transmission to healthy plants after pollination than pollen from RBΔ1bstop-infected wild type plants. Moreover, viral gRNA accumulation in pollen grains from RBΔ1bstop-infected 1b-plants was higher than in pollen from RBΔ1bstop-infected wild type plants. We suggest that 1b increases the amount of viral gRNAs released from elongating pollen grains.
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Affiliation(s)
- Masamichi Isogai
- Plant Pathology Laboratory, Faculty of Agriculture, Iwate University, Ueda 3-chome 18-8, Morioka, 020-8550, Iwate, Japan.
| | - Takanori Matsudaira
- Plant Pathology Laboratory, Faculty of Agriculture, Iwate University, Ueda 3-chome 18-8, Morioka, 020-8550, Iwate, Japan
| | - Kotaro Miyoshi
- Plant Pathology Laboratory, Faculty of Agriculture, Iwate University, Ueda 3-chome 18-8, Morioka, 020-8550, Iwate, Japan
| | - Takuya Shimura
- Plant Pathology Laboratory, Faculty of Agriculture, Iwate University, Ueda 3-chome 18-8, Morioka, 020-8550, Iwate, Japan
| | - Sayaka Torii
- Plant Pathology Laboratory, Faculty of Agriculture, Iwate University, Ueda 3-chome 18-8, Morioka, 020-8550, Iwate, Japan
| | - Nobuyuki Yoshikawa
- Plant Pathology Laboratory, Faculty of Agriculture, Iwate University, Ueda 3-chome 18-8, Morioka, 020-8550, Iwate, Japan
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91
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Baebler Š, Coll A, Gruden K. Plant Molecular Responses to Potato Virus Y: A Continuum of Outcomes from Sensitivity and Tolerance to Resistance. Viruses 2020; 12:E217. [PMID: 32075268 PMCID: PMC7077201 DOI: 10.3390/v12020217] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/11/2020] [Accepted: 02/13/2020] [Indexed: 12/25/2022] Open
Abstract
Potato virus Y (PVY) is the most economically important virus affecting potato production. PVY manipulates the plant cell machinery in order to successfully complete the infecting cycle. On the other side, the plant activates a sophisticated multilayer immune defense response to combat viral infection. The balance between these mechanisms, depending on the plant genotype and environment, results in a specific outcome that can be resistance, sensitivity, or tolerance. In this review, we summarize and compare the current knowledge on molecular events, leading to different phenotypic outcomes in response to PVY and try to link them with the known molecular mechanisms.
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92
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The RNA-Dependent RNA Polymerase NIb of Potyviruses Plays Multifunctional, Contrasting Roles during Viral Infection. Viruses 2020; 12:v12010077. [PMID: 31936267 PMCID: PMC7019339 DOI: 10.3390/v12010077] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 12/28/2019] [Accepted: 01/03/2020] [Indexed: 12/14/2022] Open
Abstract
Potyviruses represent the largest group of known plant RNA viruses and include many agriculturally important viruses, such as Plum pox virus, Soybean mosaic virus, Turnip mosaic virus, and Potato virus Y. Potyviruses adopt polyprotein processing as their genome expression strategy. Among the 11 known viral proteins, the nuclear inclusion protein b (NIb) is the RNA-dependent RNA polymerase responsible for viral genome replication. Beyond its principal role as an RNA replicase, NIb has been shown to play key roles in diverse virus–host interactions. NIb recruits several host proteins into the viral replication complexes (VRCs), which are essential for the formation of functional VRCs for virus multiplication, and interacts with the sumoylation pathway proteins to suppress NPR1-mediated immunity response. On the other hand, NIb serves as a target of selective autophagy as well as an elicitor of effector-triggered immunity, resulting in attenuated virus infection. These contrasting roles of NIb provide an excellent example of the complex co-evolutionary arms race between plant hosts and potyviruses. This review highlights the current knowledge about the multifunctional roles of NIb in potyvirus infection, and discusses future research directions.
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93
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Chowdhury RN, Lasky D, Karki H, Zhang Z, Goyer A, Halterman D, Rakotondrafara AM. HCPro Suppression of Callose Deposition Contributes to Strain-Specific Resistance Against Potato Virus Y. PHYTOPATHOLOGY 2020; 110:164-173. [PMID: 31532352 DOI: 10.1094/phyto-07-19-0229-fi] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Potato virus Y (PVY; Potyviridae) is a continuing challenge for potato production owing to the increasing popularity of strain-specific resistant cultivars. Hypersensitive resistance (HR) is one type of plant defense responses to restrict virus spread. In many potato cultivars, such as cultivar Premier Russet (PR), local necrosis at the site of infection protects against the most common PVYO strain, but the HR often fails to restrain necrotic strains, which spread systemically. Here, we established the role of callose accumulation in the strain-specific resistance responses to PVY infection. We first uncovered that PVY, independent of the strain, is naturally capable of suppressing pathogenesis-related callose formation in a susceptible host. Such activity can be dissociated from viral replication by the transient expression of the viral-encoded helper component proteinase (HCPro) protein, identifying it as the pathogen elicitor. However, unlike the necrotic strain, PVYO and its corresponding HCPro are unable to block callose accumulation in resistant PR potatoes, in which we observed an abundance of callose deposition and the inability of the virus to spread. The substitution of eight amino acid residues within the HCPro C-terminal region that differ between PVYO and PVYN strains and were previously shown to be responsible for eliciting the HR response, are sufficient to restore the ability of HCProO to suppress callose accumulation, despite the resistant host background, in line with a new viral function in pathogenicity.
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Affiliation(s)
- Rawnaq N Chowdhury
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, U.S.A
| | - Danny Lasky
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, U.S.A
| | - Hari Karki
- U.S. Department of Agriculture-Agricultural Research Service, Madison, WI 53706, U.S.A
| | - Zongying Zhang
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, U.S.A
- Ministry of Agriculture Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Aymeric Goyer
- Department of Botany and Plant Pathology, Hermiston Agricultural Research and Extension Center, Oregon State University, Hermiston, OR 97838, U.S.A
| | - Dennis Halterman
- U.S. Department of Agriculture-Agricultural Research Service, Madison, WI 53706, U.S.A
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94
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Tuo D, Zhou P, Zhao G, Yan P, Tan D, Li X, Shen W. A Double Mutation in the Conserved Motifs of the Helper Component Protease of Papaya Leaf Distortion Mosaic Virus for the Generation of a Cross-Protective Attenuated Strain. PHYTOPATHOLOGY 2020; 110:187-193. [PMID: 31516080 DOI: 10.1094/phyto-09-19-0328-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Potyviral helper component protease (HC-Pro), as a major determinant of symptom expression in susceptible plants, is a likely target candidate in the production of attenuated strains for cross-protection. In this study, single or double mutations of Lys (K) to Glu (E) in the Lys-Ile-Thr-Cys motif and Arg (R) to Ile (I) in the Phe-Arg-Asn-Lys motif of the HC-Pro from the severe papaya leaf distortion mosaic virus strain DF (PLDMV-DF) reduced symptom expression and virus accumulation in infected papaya (Carica papaya) plants. The papaya plants infected with the attenuated double mutant of PLDMV-EI presented as symptomless. PLDMV-EI provided effective protection against PLDMV-DF infection in three papaya cultivars and had no effect on plant growth and development. Our result showed that PLDMV-EI is a promising mild strain for the practical use of cross-protection in the field.
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Affiliation(s)
- Decai Tuo
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture & Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
- Hainan Key Laboratory of Tropical Microbe Resources, Haikou 571101, China
| | - Peng Zhou
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture & Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
- Hainan Key Laboratory of Tropical Microbe Resources, Haikou 571101, China
| | - Guangyuan Zhao
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture & Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
- Institute of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China
| | - Pu Yan
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture & Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
- Hainan Key Laboratory of Tropical Microbe Resources, Haikou 571101, China
| | - Dong Tan
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture & Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Xiaoying Li
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture & Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
- Hainan Key Laboratory of Tropical Microbe Resources, Haikou 571101, China
| | - Wentao Shen
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture & Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
- Hainan Key Laboratory of Tropical Microbe Resources, Haikou 571101, China
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95
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Tatineni S, Stewart LR, Sanfaçon H, Wang X, Navas-Castillo J, Hajimorad MR. Fundamental Aspects of Plant Viruses-An Overview on Focus Issue Articles. PHYTOPATHOLOGY 2020; 110:6-9. [PMID: 31910089 DOI: 10.1094/phyto-10-19-0404-fi] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Given the importance of and rapid research progress in plant virology in recent years, this Focus Issue broadly emphasizes advances in fundamental aspects of virus infection cycles and epidemiology. This Focus Issue comprises three review articles and 18 research articles. The research articles cover broad research areas on the identification of novel viruses, the development of detection methods, reverse genetics systems and functional genomics for plant viruses, vector and seed transmission studies, viral population studies, virus-virus interactions and their effect on vector transmission, and management strategies of viral diseases. The three review articles discuss recent developments in application of prokaryotic clustered regularly interspaced short palindromic repeats/CRISPR-associated genes (CRISPR/Cas) technology for plant virus resistance, mixed viral infections and their role in disease synergism and cross-protection, and viral transmission by whiteflies. The following briefly summarizes the articles appearing in this Focus Issue.
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Affiliation(s)
- Satyanarayana Tatineni
- U.S. Department of Agriculture-Agricultural Research Service and Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE, U.S.A
| | - Lucy R Stewart
- U.S. Department of Agriculture-Agricultural Research Service, Corn, Soybean, and Wheat Quality Research Unit, Wooster, OH, U.S.A
| | - Hélène Sanfaçon
- Summerland Research and Development Centre, Agriculture and Agri-Food Canada, Summerland, BC V0H 1Z0, Canada
| | - Xiaofeng Wang
- School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA, U.S.A
| | - Jesús Navas-Castillo
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Consejo Superior de Investigaciones Científicas-Universidad de Málaga, 29750 Algarrobo-Costa, Málaga, Spain
| | - M Reza Hajimorad
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN, U.S.A
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96
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Abstract
The pathological importance of mixed viral infections in plants might be underestimated except for a few well-characterized synergistic combinations in certain crops. Considering that the host ranges of many viruses often overlap and that most plant species can be infected by several unrelated viruses, it is not surprising to find more than one virus simultaneously in the same plant. Furthermore, dispersal of the majority of plant viruses relies on efficient transmission mechanisms mediated by vector organisms, mainly but not exclusively insects, which can contribute to the occurrence of multiple infections in the same plant. Recent work using different experimental approaches has shown that mixed viral infections can be remarkably frequent, up to the point that they could be considered the rule more than the exception. The purpose of this review is to describe the impact of multiple infections not only on the participating viruses themselves but also on their vectors and on the common host. From this standpoint, mixed infections arise as complex events that involve several cross-interacting players, and they consequently require a more general perspective than the analysis of single-virus/single-host approaches for a full understanding of their relevance.
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Affiliation(s)
- Ana Beatriz Moreno
- Centre for Research in Agricultural Genomics, Consejo Superior de Investigaciones Científicas IRTA-UAB-UB, Cerdanyola del Vallès, Barcelona, Spain
| | - Juan José López-Moya
- Centre for Research in Agricultural Genomics, Consejo Superior de Investigaciones Científicas IRTA-UAB-UB, Cerdanyola del Vallès, Barcelona, Spain
- Consejo Superior de Investigaciones Científicas, Barcelona, Spain
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97
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Wang Y, Xu W, Abe J, Nakahara KS, Hajimorad MR. Precise Exchange of the Helper-Component Proteinase Cistron Between Soybean mosaic virus and Clover yellow vein virus: Impact on Virus Viability and Host Range Specificity. PHYTOPATHOLOGY 2020; 110:206-214. [PMID: 31509476 DOI: 10.1094/phyto-06-19-0193-fi] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Soybean mosaic virus and Clover yellow vein virus are two definite species of the genus Potyvirus within the family Potyviridae. Soybean mosaic virus-N (SMV-N) is well adapted to cultivated soybean (Glycine max) genotypes and wild soybean (G. soja), whereas it remains undetectable in inoculated broad bean (Vicia faba). In contrast, clover yellow vein virus No. 30 (ClYVV-No. 30) is capable of systemic infection in broad bean and wild soybean; however, it infects cultivated soybean genotypes only locally. In this study, SMV-N was shown to also infect broad bean locally; hence, broad bean is a host for SMV-N. Based on these observations, it was hypothesized that lack of systemic infection by SMV-N in broad bean and by ClYVV-No. 30 in cultivated soybean is attributable to the incompatibility of multifunctional helper-component proteinase (HC-Pro) in these hosts. The logic of selecting the HC-Pro cistron as a target is based on its established function in systemic movement and being a relevant factor in host range specificity of potyviruses. To test this hypothesis, chimeras were constructed with precise exchanges of HC-Pro cistrons between SMV-N and ClYVV-No. 30. Upon inoculation, both chimeras were viable in infection, but host range specificity of the recombinant viruses did not differ from those of the parental viruses. These observations suggest that (i) HC-Pro cistrons from SMV-N and ClYVV-No. 30 are functionally compatible in infection despite 55.6 and 48.9% nucleotide and amino acid sequence identity, respectively, and (ii) HC-Pro cistrons from SMV-N and ClYVV-No. 30 are not the determinants of host specificity on cultivated soybean or broad beans, respectively.
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Affiliation(s)
- Y Wang
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, U.S.A
- Jilin Academy of Agricultural Sciences, Changchun 130033, Jilin, China
| | - W Xu
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, U.S.A
| | - J Abe
- Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
| | - K S Nakahara
- Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
| | - M R Hajimorad
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, U.S.A
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98
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Domingo-Calap ML, Moreno AB, Díaz Pendón JA, Moreno A, Fereres A, López-Moya JJ. Assessing the Impact on Virus Transmission and Insect Vector Behavior of a Viral Mixed Infection in Melon. PHYTOPATHOLOGY 2020; 110:174-186. [PMID: 31502517 DOI: 10.1094/phyto-04-19-0126-fi] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Mixed viral infections in plants are common, and can result in synergistic or antagonistic interactions. Except in complex diseases with severe symptoms, mixed infections frequently remain unnoticed, and their impact on insect vector transmission is largely unknown. In this study, we considered mixed infections of two unrelated viruses commonly found in melon plants, the crinivirus cucurbit yellow stunting disorder virus (CYSDV) and the potyvirus watermelon mosaic virus (WMV), and evaluated their vector transmission by whiteflies and aphids, respectively. Their dynamics of accumulation was analyzed until 60 days postinoculation (dpi) in mixed-infected plants, documenting reduced titers of WMV and much higher titers of CYSDV compared with single infections. At 24 dpi, corresponding to the peak of CYSDV accumulation, similar whitefly transmission rates were obtained when comparing either individual or mixed-infected plants as CYSDV sources, although its secondary dissemination was slightly biased toward plants previously infected with WMV, regardless of the source plant. However, at later time points, mixed-infected plants partially recovered from the initially severe symptoms, and CYSDV transmission became significantly higher. Interestingly, aphid transmission rates both at early and late time points were unaltered when WMV was acquired from mixed-infected plants despite its reduced accumulation. This lack of correlation between WMV accumulation and transmission could result from compensatory effects observed in the analysis of the aphid feeding behavior by electrical penetration graphs. Thus, our results showed that mixed-infected plants could provide advantages for both viruses, directly favoring CYSDV dissemination while maintaining WMV transmission.
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Affiliation(s)
- Maria Luisa Domingo-Calap
- Centre for Research in Agricultural Genomics (CRAG), Consejo Superior de Investigaciones Científicas (CSIC)-IRTA-UAB-UB, Cerdanyola del Vallès, Barcelona, Spain
| | - Ana Beatriz Moreno
- Centre for Research in Agricultural Genomics (CRAG), Consejo Superior de Investigaciones Científicas (CSIC)-IRTA-UAB-UB, Cerdanyola del Vallès, Barcelona, Spain
| | - Juan Antonio Díaz Pendón
- Institute for Mediterranean and Subtropical Horticulture "La Mayora" (IHSM-UMA-CSIC), Algarrobo-Costa, Málaga, Spain
| | - Aranzazu Moreno
- Institute of Agricultural Sciences, ICA, CSIC, Madrid, Spain
| | - Alberto Fereres
- Institute of Agricultural Sciences, ICA, CSIC, Madrid, Spain
| | - Juan José López-Moya
- Centre for Research in Agricultural Genomics (CRAG), Consejo Superior de Investigaciones Científicas (CSIC)-IRTA-UAB-UB, Cerdanyola del Vallès, Barcelona, Spain
- CSIC, Barcelona, Spain
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99
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Ibrahim A, Fros J, Bertran A, Sechan F, Odon V, Torrance L, Kormelink R, Simmonds P. A functional investigation of the suppression of CpG and UpA dinucleotide frequencies in plant RNA virus genomes. Sci Rep 2019; 9:18359. [PMID: 31797900 PMCID: PMC6892864 DOI: 10.1038/s41598-019-54853-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 11/19/2019] [Indexed: 01/08/2023] Open
Abstract
Frequencies of CpG and UpA dinucleotides in most plant RNA virus genomes show degrees of suppression comparable to those of vertebrate RNA viruses. While pathways that target CpG and UpAs in HIV-1 and echovirus 7 genomes and restrict their replication have been partly characterised, whether an analogous process drives dinucleotide underrepresentation in plant viruses remains undetermined. We examined replication phenotypes of compositionally modified mutants of potato virus Y (PVY) in which CpG or UpA frequencies were maximised in non-structural genes (including helicase and polymerase encoding domains) while retaining protein coding. PYV mutants with increased CpG dinucleotide frequencies showed a dose-dependent reduction in systemic spread and pathogenicity and up to 1000-fold attenuated replication kinetics in distal sites on agroinfiltration of tobacco plants (Nicotiana benthamiana). Even more extraordinarily, comparably modified UpA-high mutants displayed no pathology and over a million-fold reduction in replication. Tobacco plants with knockdown of RDP6 displayed similar attenuation of CpG- and UpA-high mutants suggesting that restriction occurred independently of the plant siRNA antiviral responses. Despite the evolutionary gulf between plant and vertebrate genomes and encoded antiviral strategies, these findings point towards the existence of novel virus restriction pathways in plants functionally analogous to innate defence components in vertebrate cells.
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Affiliation(s)
- Ahmad Ibrahim
- Nuffield Department of Medicine, Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, OX1 3SY, UK
| | - Jelke Fros
- Nuffield Department of Medicine, Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, OX1 3SY, UK
- Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708, PB, Wageningen, The Netherlands
| | - Andre Bertran
- Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708, PB, Wageningen, The Netherlands
| | - Ferdyansyah Sechan
- Nuffield Department of Medicine, Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, OX1 3SY, UK
| | - Valerie Odon
- Nuffield Department of Medicine, Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, OX1 3SY, UK
| | - Leslie Torrance
- The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Richard Kormelink
- Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708, PB, Wageningen, The Netherlands
| | - Peter Simmonds
- Nuffield Department of Medicine, Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, OX1 3SY, UK.
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100
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Liu Q, Hobbs HA, Domier LL. Genome-wide association study of the seed transmission rate of soybean mosaic virus and associated traits using two diverse population panels. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2019; 132:3413-3424. [PMID: 31630210 DOI: 10.1007/s00122-019-03434-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 09/17/2019] [Indexed: 06/10/2023]
Abstract
KEY MESSAGE Genome-wide association analyses identified candidates for genes involved in restricting virus movement into embryonic tissues, suppressing virus-induced seed coat mottling and preserving yield in soybean plants infected with soybean mosaic virus. Soybean mosaic virus (SMV) causes significant reductions in soybean yield and seed quality. Because seedborne infections can serve as primary sources of inoculum for SMV infections, resistance to SMV seed transmission provides a means to limit the impacts of SMV. In this study, two diverse population panels, Pop1 and Pop2, composed of 409 and 199 soybean plant introductions, respectively, were evaluated for SMV seed transmission rate, seed coat mottling, and seed yield from SMV-infected plants. The phenotypic data and genotypic data from the SoySNP50K dataset were analyzed using GAPIT and rrBLUP. For SMV seed transmission rate, a single locus was identified on chromosome 9 in Pop1. For SMV-induced seed coat mottling, loci were identified on chromosome 9 in Pop1 and on chromosome 3 in Pop2. For seed yield from SMV-infected plants, a single locus was identified on chromosome 3 in Pop2 that was within the map interval of a previously described quantitative trait locus for seed number. The high linkage disequilibrium regions surrounding the markers on chromosomes 3 and 9 contained a predicted nonsense-mediated RNA decay gene, multiple pectin methylesterase inhibitor genes (involved in restricting virus movement), two chalcone synthase genes, and a homolog of the yeast Rtf1 gene (involved in RNA-mediated transcriptional gene silencing). The results of this study provided additional insight into the genetic architecture of these three important traits, suggested candidate genes for downstream functional validation, and suggested that genomic prediction would outperform marker-assisted selection for two of the four trait-marker associations.
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Affiliation(s)
- Qiong Liu
- Department of Crop Sciences, University of Illinois, Urbana, IL, 61801, USA
| | - Houston A Hobbs
- Department of Crop Sciences, University of Illinois, Urbana, IL, 61801, USA
| | - Leslie L Domier
- Soybean/Maize Germplasm, Pathology, and Genetics Research Unit, United States Department of Agriculture-Agricultural Research Service, Urbana, IL, 61801, USA.
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