1
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Qiao Z, Wang J, Huang K, Hu H, Gu Z, Liao Q, Du Z. The non-template functions of helper virus RNAs create optimal replication conditions to enhance the proliferation of satellite RNAs. PLoS Pathog 2024; 20:e1012174. [PMID: 38630801 PMCID: PMC11057728 DOI: 10.1371/journal.ppat.1012174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 04/29/2024] [Accepted: 04/07/2024] [Indexed: 04/19/2024] Open
Abstract
As a type of parasitic agent, satellite RNAs (satRNAs) rely on cognate helper viruses to achieve their replication and transmission. During the infection of satRNAs, helper virus RNAs serve as templates for synthesizing viral proteins, including the replication proteins essential for satRNA replication. However, the role of non-template functions of helper virus RNAs in satRNA replication remains unexploited. Here we employed the well-studied model that is composed of cucumber mosaic virus (CMV) and its associated satRNA. In the experiments employing the CMV trans-replication system, we observed an unexpected phenomenon the replication proteins of the mild strain LS-CMV exhibited defective in supporting satRNA replication, unlike those of the severe strain Fny-CMV. Independent of translation products, all CMV genomic RNAs could enhance satRNA replication, when combined with the replication proteins of CMV. This enhancement is contingent upon the recruitment and complete replication of helper virus RNAs. Using the method developed for analyzing the satRNA recruitment, we observed a markedly distinct ability of the replication proteins from both CMV strains to recruit the positive-sense satRNA-harboring RNA3 mutant for replication. This is in agreement with the differential ability of both 1a proteins in binding satRNAs in plants. The discrepancies provide a convincing explanation for the variation of the replication proteins of both CMV strains in replicating satRNAs. Taken together, our work provides compelling evidence that the non-template functions of helper virus RNAs create an optimal replication environment to enhance satRNA proliferation.
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Affiliation(s)
- Zimu Qiao
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, Zhejiang, China
| | - Jin Wang
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, Zhejiang, China
| | - Kaiyun Huang
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, Zhejiang, China
| | - Honghao Hu
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, Zhejiang, China
| | - Zhouhang Gu
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, Zhejiang, China
| | - Qiansheng Liao
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, Zhejiang, China
| | - Zhiyou Du
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, Zhejiang, China
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2
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Abstract
Robust plant immune systems are fine-tuned by both protein-coding genes and non-coding RNAs. Long non-coding RNAs (lncRNAs) refer to RNAs with a length of more than 200 nt and usually do not have protein-coding function and do not belong to any other well-known non-coding RNA types. The non-protein-coding, low expression, and non-conservative characteristics of lncRNAs restrict their recognition. Although studies of lncRNAs in plants are in the early stage, emerging studies have shown that plants employ lncRNAs to regulate plant immunity. Moreover, in response to stresses, numerous lncRNAs are differentially expressed, which manifests the actions of low-expressed lncRNAs and makes plant-microbe/insect interactions a convenient system to study the functions of lncRNAs. Here, we summarize the current advances in plant lncRNAs, discuss their regulatory effects in different stages of plant immunity, and highlight their roles in diverse plant-microbe/insect interactions. These insights will not only strengthen our understanding of the roles and actions of lncRNAs in plant-microbe/insect interactions but also provide novel insight into plant immune responses and a basis for further research in this field.
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Affiliation(s)
- Juan Huang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Wenling Zhou
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Xiaoming Zhang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
- HainanYazhou Bay Seed Lab, Sanya, China
| | - Yi Li
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
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3
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Jin Y, Zhao JH, Guo HS. Recent advances in understanding plant antiviral RNAi and viral suppressors of RNAi. Curr Opin Virol 2020; 46:65-72. [PMID: 33360834 DOI: 10.1016/j.coviro.2020.12.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 12/01/2020] [Accepted: 12/03/2020] [Indexed: 10/22/2022]
Abstract
Molecular plant-virus interactions provide an excellent model to understanding host antiviral immunity and viral counter-defense mechanisms. The primary antiviral defense is triggered inside the infected plant cell by virus-derived small-interfering RNAs, which guide homology-dependent RNA interference (RNAi) and/or RNA-directed DNA methylation (RdDM) to target RNA and DNA viruses. In counter-defense, plant viruses have independently evolved viral suppressors of RNAi (VSRs) to specifically antagonize antiviral RNAi. Recent studies have shown that plant antiviral responses are regulated by endogenous small silencing RNAs, RNA decay and autophagy and that some known VSRs of plant RNA and DNA viruses also target these newly recognized defense responses to promote infection. This review focuses on these recent advances that have revealed multilayered regulation of plant-virus interactions.
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Affiliation(s)
- Yun Jin
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, CAS Center for Excellence in Biotic Interactions, University of the Chinese Academy of Sciences, Beijing 100049, China.
| | - Jian-Hua Zhao
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, CAS Center for Excellence in Biotic Interactions, University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Hui-Shan Guo
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, CAS Center for Excellence in Biotic Interactions, University of the Chinese Academy of Sciences, Beijing 100049, China
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4
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Badar U, Venkataraman S, AbouHaidar M, Hefferon K. Molecular interactions of plant viral satellites. Virus Genes 2020; 57:1-22. [PMID: 33226576 DOI: 10.1007/s11262-020-01806-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 10/24/2020] [Indexed: 12/18/2022]
Abstract
Plant viral satellites fall under the category of subviral agents. Their genomes are composed of small RNA or DNA molecules a few hundred nucleotides in length and contain an assortment of highly complex and overlapping functions. Each lacks the ability to either replicate or undergo encapsidation or both in the absence of a helper virus (HV). As the number of known satellites increases steadily, our knowledge regarding their sequence conservation strategies, means of replication and specific interactions with host and helper viruses is improving. This review demonstrates that the molecular interactions of these satellites are unique and highly complex, largely influenced by the highly specific host plants and helper viruses that they associate with. Circularized forms of single-stranded RNA are of particular interest, as they have recently been found to play a variety of novel cellular functions. Linear forms of satRNA are also of great significance as they may complement the helper virus genome in exacerbating symptoms, or in certain instances, actively compete against it, thus reducing symptom severity. This review serves to describe the current literature with respect to these molecular mechanisms in detail as well as to discuss recent insights into this emerging field in terms of evolution, classification and symptom development. The review concludes with a discussion of future steps in plant viral satellite research and development.
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Affiliation(s)
- Uzma Badar
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | | | - Mounir AbouHaidar
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Kathleen Hefferon
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada.
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5
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Shrestha N, Bujarski JJ. Long Noncoding RNAs in Plant Viroids and Viruses: A Review. Pathogens 2020; 9:E765. [PMID: 32961969 PMCID: PMC7559573 DOI: 10.3390/pathogens9090765] [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: 08/27/2020] [Revised: 09/15/2020] [Accepted: 09/16/2020] [Indexed: 12/11/2022] Open
Abstract
Infectious long-noncoding (lnc) RNAs related to plants can be of both viral and non-viral origin. Viroids are infectious plant lncRNAs that are not related to viruses and carry the circular, single-stranded, non-coding RNAs that replicate with host enzymatic activities via a rolling circle mechanism. Viroids interact with host processes in complex ways, emerging as one of the most productive tools for studying the functions of lncRNAs. Defective (D) RNAs, another category of lnc RNAs, are found in a variety of plant RNA viruses, most of which are noncoding. These are derived from and are replicated by the helper virus. D RNA-virus interactions evolve into mutually beneficial combinations, enhancing virus fitness via competitive advantages of moderated symptoms. Yet the satellite RNAs are single-stranded and include either large linear protein-coding ss RNAs, small linear ss RNAs, or small circular ss RNAs (virusoids). The satellite RNAs lack sequence homology to the helper virus, but unlike viroids need a helper virus to replicate and encapsidate. They can attenuate symptoms via RNA silencing and enhancement of host defense, but some can be lethal as RNA silencing suppressor antagonists. Moreover, selected viruses produce lncRNAs by incomplete degradation of genomic RNAs. They do not replicate but may impact viral infection, gene regulation, and cellular functions. Finally, the host plant lncRNAs can also contribute during plant-virus interactions, inducing plant defense and the regulation of gene expression, often in conjunction with micro and/or circRNAs.
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Affiliation(s)
- Nipin Shrestha
- Department of Biological Sciences and Plant Molecular and Bioinformatics Center, Northern Illinois University, DeKalb, IL 60115, USA
| | - Józef J. Bujarski
- Department of Biological Sciences and Plant Molecular and Bioinformatics Center, Northern Illinois University, DeKalb, IL 60115, USA
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6
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Leonetti P, Miesen P, van Rij RP, Pantaleo V. Viral and subviral derived small RNAs as pathogenic determinants in plants and insects. Adv Virus Res 2020; 107:1-36. [PMID: 32711727 DOI: 10.1016/bs.aivir.2020.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The phenotypic manifestations of disease induced by viruses and subviral infectious entities are the result of complex molecular interactions between host and viral factors. The viral determinants of the diseased phenotype have traditionally been sought at the level of structural or non-structural proteins. However, the discovery of RNA silencing mechanisms has led to speculations that determinants of the diseased phenotype are caused by viral nucleic acid sequences in addition to proteins. RNA silencing is a gene regulation mechanism conserved within eukaryotic kingdoms (with the exception of some yeast species), and in plants and insects it also functions as an antiviral mechanism. Non-coding RNAs of viral origin, ranging in size from 21 to 24 nucleotides (viral small interfering RNAs, vsiRNAs) accumulate in virus-infected tissues and organs, in some cases to comparable levels as the entire complement of host-encoded small interfering RNAs. Upon incorporation into RNA-induced silencing complexes, vsiRNAs can mediate cleavage or induce translational inhibition of nucleic acid targets in a sequence-specific manner. This review focuses on recent findings that suggest an increased complexity of small RNA-based interactions between virus and host. We mainly address plant viruses, but where applicable discuss insect viruses as well. Prominence is given to studies that have indisputably demonstrated that vsiRNAs determine diseased phenotype by either carrying sequence determinants or, indirectly, by altering host-gene regulatory pathways. Results from these studies suggest biotechnological applications, which are also discussed.
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Affiliation(s)
- Paola Leonetti
- Department of Biology, Agricultural and Food Sciences, Institute for Sustainable Plant Protection, CNR, Bari, Italy
| | - Pascal Miesen
- Department of Medical Microbiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ronald P van Rij
- Department of Medical Microbiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.
| | - Vitantonio Pantaleo
- Department of Biology, Agricultural and Food Sciences, Institute for Sustainable Plant Protection, CNR, Bari, Italy..
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7
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Zhao JH, Guo HS. Trans-kingdom RNA interactions drive the evolutionary arms race between hosts and pathogens. Curr Opin Genet Dev 2019; 58-59:62-69. [PMID: 31472442 DOI: 10.1016/j.gde.2019.07.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 07/23/2019] [Accepted: 07/30/2019] [Indexed: 12/12/2022]
Abstract
Trans-kingdom RNA plays a key role in host-parasite interactions. Hosts export specific endogenous microRNAs (miRNAs) into pathogens to target pathogen virulence genes and inhibit their invasion. In addition, trans-kingdom sRNAs produced by parasites may function as RNA effectors to suppress host immunity. Here, we summarize recent, important findings regarding trans-kingdom RNA and focus on the roles of trans-kingdom RNA in driving an evolutionary arms race between host and pathogen. We suggest that trans-kingdom RNA is a new platform for such arms races. Furthermore, we conjecture that trans-kingdom RNA contributes to horizontal gene transfer (HGT) involved in host-pathogen interactions. In addition, we propose that trans-kingdom RNA exchange and RNA driven HGT can have a great impact on the evolutionary ecology of interacting species.
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Affiliation(s)
- Jian-Hua Zhao
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, 100101 Beijing, China
| | - Hui-Shan Guo
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, 100101 Beijing, China; CAS Center for Excellence in Biotic Interactions, University of the Chinese Academy of Sciences, 100049 Beijing, China.
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8
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Pooggin MM. Small RNA-Omics for Plant Virus Identification, Virome Reconstruction, and Antiviral Defense Characterization. Front Microbiol 2018; 9:2779. [PMID: 30524398 PMCID: PMC6256188 DOI: 10.3389/fmicb.2018.02779] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 10/30/2018] [Indexed: 11/13/2022] Open
Abstract
RNA interference (RNAi)-based antiviral defense generates small interfering RNAs that represent the entire genome sequences of both RNA and DNA viruses as well as viroids and viral satellites. Therefore, deep sequencing and bioinformatics analysis of small RNA population (small RNA-ome) allows not only for universal virus detection and genome reconstruction but also for complete virome reconstruction in mixed infections. Viral infections (like other stress factors) can also perturb the RNAi and gene silencing pathways regulating endogenous gene expression and repressing transposons and host genome-integrated endogenous viral elements which can potentially be released from the genome and contribute to disease. This review describes the application of small RNA-omics for virus detection, virome reconstruction and antiviral defense characterization in cultivated and non-cultivated plants. Reviewing available evidence from a large and ever growing number of studies of naturally or experimentally infected hosts revealed that all families of land plant viruses, their satellites and viroids spawn characteristic small RNAs which can be assembled into contigs of sufficient length for virus, satellite or viroid identification and for exhaustive reconstruction of complex viromes. Moreover, the small RNA size, polarity and hotspot profiles reflect virome interactions with the plant RNAi machinery and allow to distinguish between silent endogenous viral elements and their replicating episomal counterparts. Models for the biogenesis and functions of small interfering RNAs derived from all types of RNA and DNA viruses, satellites and viroids as well as endogenous viral elements are presented and discussed.
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Affiliation(s)
- Mikhail M. Pooggin
- Institut National de la Recherche Agronomique, UMR BGPI, Montpellier, France
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9
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CMV2b-Dependent Regulation of Host Defense Pathways in the Context of Viral Infection. Viruses 2018; 10:v10110618. [PMID: 30423959 PMCID: PMC6265714 DOI: 10.3390/v10110618] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Revised: 11/06/2018] [Accepted: 11/08/2018] [Indexed: 01/26/2023] Open
Abstract
RNA silencing (or RNA interference, RNAi) plays direct roles in plant host defenses against viruses. Viruses encode suppressors of RNAi (VSRs) to counteract host antiviral defenses. The generation of transgenic plants expressing VSRs facilitates the understanding of the mechanisms of VSR-mediated interference with the endogenous silencing pathway. However, studying VSRs independent of other viral components simplifies the complex roles of VSRs during natural viral infection. While suppression of transgene silencing by the VSR 2b protein encoded by cucumber mosaic virus (CMV) requires 2b-small RNA (sRNA) binding activity, suppression of host antiviral defenses requires the binding activity of both sRNAs and AGOs proteins. This study, aimed to understand the functions of 2b in the context of CMV infection; thus, we performed genome-wide analyses of differential DNA methylation regions among wild-type CMV-infected, CMVΔ2b-infected, and 2b-transgenic Arabidopsis plants. These analyses, together with transcriptome sequencing and RT-qPCR analyses, show that while the majority of induced genes in 2b-transgenic plants were involved in extensive metabolic pathways, CMV-infection 2b-dependent induced genes were enriched in plant immunity pathways, including salicylic acid (SA) signaling. Together with infection with CMV mutants that expressed the 2b functional domains of sRNA or AGO binding, our data demonstrate that CMV-accelerated SA signaling depends on 2b-sRNA binding activity which is also responsible for virulence.
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10
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Giakountis A, Tsarmpopoulos I, Chatzivassiliou EK. Cucumber mosaic virus Isolates from Greek Legumes are Associated with Satellite RNAs that are Necrogenic for Tomato. PLANT DISEASE 2018; 102:2268-2276. [PMID: 30189158 DOI: 10.1094/pdis-08-17-1259-re] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Worldwide, Cucumber mosaic virus (CMV) is the causal agent of many economically important diseases. Based on immunological or molecular analysis, three distinct subgroups of CMV isolates can be identified (IA, IB, and II). In addition, some CMV isolates are associated with satellite RNAs (satRNAs), a type of noncoding transcript that may alter the symptoms of CMV infections. This study presents an analysis of CMV isolates occurring in legumes in Greece in respect to their genetic diversity, and the presence and diversity of their satRNA. Phylogenetic analysis of the CMV coat protein sequence of 18 legume and 5 tomato CMV isolates collected throughout Greece classified them within subgroups IA and IB, with a limited genetic diversity. The CMV satRNAs found in nine field legumes exhibiting mild symptoms and in one tomato with a necrotic syndrome contained a functional necrogenic motif; therefore, they were grouped within the necrogenic group of CMV-satRNAs. The necrotic phenotype was expressed in all legume CMV isolates containing necrogenic satRNAs when mechanically inoculated onto tomato plants. To our knowledge, this is the first observation that legumes host necrogenic CMV-satRNAs. The possible role of legumes in the epidemiology of CMV and necrogenic satRNA complex is discussed.
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Affiliation(s)
- Antonis Giakountis
- Agricultural University of Athens, School of Agricultural Production, Infrastructure and Environment, Department of Crop Science, Plant Pathology Laboratory, Iera Odos 75, Votanikos, 11855 Athens, Greece
| | - Iason Tsarmpopoulos
- Agricultural University of Athens, School of Agricultural Production, Infrastructure and Environment, Department of Crop Science, Plant Pathology Laboratory, Iera Odos 75, Votanikos, 11855 Athens, Greece
| | - Elisavet K Chatzivassiliou
- Agricultural University of Athens, School of Agricultural Production, Infrastructure and Environment, Department of Crop Science, Plant Pathology Laboratory, Iera Odos 75, Votanikos, 11855 Athens, Greece
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11
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Expression Analysis of Hairpin RNA Carrying Sugarcane mosaic virus (SCMV) Derived Sequences and Transgenic Resistance Development in a Model Rice Plant. BIOMED RESEARCH INTERNATIONAL 2017; 2017:1646140. [PMID: 28255554 PMCID: PMC5309402 DOI: 10.1155/2017/1646140] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 12/08/2016] [Accepted: 01/09/2017] [Indexed: 11/18/2022]
Abstract
Developing transgenic resistance in monocotyledonous crops against pathogens remains a challenging area of research. Sugarcane mosaic virus (SCMV) is a serious pathogen of many monocotyledonous crops including sugarcane. The objective of present study was to analyze transgenic expression of hairpin RNA (hpRNA), targeting simultaneously CP (Coat Protein) and Hc-Pro (helper component-proteinase) genes of SCMV, in a model rice plant. Conserved nucleotide sequences, exclusive for DAG (Aspartic acid-Alanine-Glycine) and KITC (Lycine-Isoleucine-Threonine-Cysteine) motifs, derived from SCMV CP and Hc-Pro genes, respectively, were fused together and assembled into the hpRNA cassette under maize ubiquitin promoter to form Ubi-hpCP:Hc-Pro construct. The same CP:Hc-Pro sequence was fused with the β-glucuronidase gene (GUS) at the 3' end under CaMV 35S promoter to develop 35S-GUS:CP:Hc-Pro served as a target reporter gene construct. When delivered into rice callus tissues by particle bombardment, the Ubi-hpCP:Hc-Pro construct induced strong silencing of 35S-GUS:CP:Hc-Pro. Transgenic rice plants, containing Ubi-hpCP:Hc-Pro construct, expressed high level of 21-24 nt small interfering RNAs, which induced specific suppression against GUS:CP:Hc-Pro delivered by particle bombardment and conferred strong resistance to mechanically inoculated SCMV. It is concluded that fusion hpRNA approach is an affordable method for developing resistance against SCMV in model rice plant and it could confer SCMV resistance when transformed into sugarcane.
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12
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Mascia T, Gallitelli D. Synergies and antagonisms in virus interactions. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2016; 252:176-192. [PMID: 27717453 DOI: 10.1016/j.plantsci.2016.07.015] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Revised: 07/22/2016] [Accepted: 07/27/2016] [Indexed: 05/25/2023]
Abstract
Metagenomic surveys and data from next generation sequencing revealed that mixed infections among plant viruses are probably a rule rather than an exception in natural pathosystems. The documented cases may range from synergism to antagonism, which may depend from the spatiotemporal order of arrival of the viruses on the host and upon the host itself. In synergistic interactions, the measurable differences in replication, phenotypic and cytopathological changes, cellular tropism, within host movement, and transmission rate of one of the two viruses or both are increased. Conversely, a decrease in replication, or inhibition of one or more of the above functions by one virus against the other, leads to an antagonistic interaction. Viruses may interact directly and by transcomplementation of defective functions or indirectly, through responses mediated by the host like the defense mechanism based on RNA silencing. Outcomes of these interactions can be applied to the risk assessment of transgenic crops expressing viral proteins, or cross-protected crops for the identification of potential hazards. Prior to experimental evidence, mathematical models may help in forecasting challenges deriving from the great variety of pathways of synergistic and antagonistic interactions. Actually, it seems that such predictions do not receive sufficient credit in the framework of agriculture.
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Affiliation(s)
- Tiziana Mascia
- Dipartimento di Scienze del Suolo della Pianta e degli Alimenti, Università degli Studi di Bari Aldo Moro, Via Amendola 165/A, 70126 Bari, Italy; Istituto del CNR per la Protezione sostenibile delle Piante, Unità Operativa di Supporto di Bari, Via Amendola 165/A, 70126 Bari, Italy
| | - Donato Gallitelli
- Dipartimento di Scienze del Suolo della Pianta e degli Alimenti, Università degli Studi di Bari Aldo Moro, Via Amendola 165/A, 70126 Bari, Italy; Istituto del CNR per la Protezione sostenibile delle Piante, Unità Operativa di Supporto di Bari, Via Amendola 165/A, 70126 Bari, Italy.
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13
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Zhao JH, Fang YY, Duan CG, Fang RX, Ding SW, Guo HS. Genome-wide identification of endogenous RNA-directed DNA methylation loci associated with abundant 21-nucleotide siRNAs in Arabidopsis. Sci Rep 2016; 6:36247. [PMID: 27786269 PMCID: PMC5081565 DOI: 10.1038/srep36247] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 10/12/2016] [Indexed: 12/29/2022] Open
Abstract
In Arabidopsis, the 24-nucleotide (nt) small interfering RNAs (siRNAs) mediates RNA-directed DNA methylation (RdDM) and transcriptional gene silencing (TGS) of transposable elements (TEs). In the present study, we examined genome-wide changes in DNA methylation and siRNA accumulation in Arabidopsis induced by expression of the Cucumber mosaic virus silencing suppressor protein 2b known to directly bind to both the 21/24-nt siRNAs as well as their associated Argonaute proteins. We demonstrated a genome-wide reduction of CHH and CHG methylation in the 2b-transgenic plants. We found that 2b suppressed RdDM not only at the previously annotated loci directed by 24-nt siRNAs but also a new set of loci associated with 21/22-nt siRNAs. Further analysis showed that the reduced methylation of TEs and coding genes targeted by 21/22-nt siRNAs was associated with sequestration of the duplex siRNAs by the 2b protein but not with changes in either siRNA production or transcription. Notably, we detected both the deletion and/or the transposition of multicopy TEs associated with 2b-induced hypomethylation, suggesting potential TE reactivation. We propose that the silencing of many TEs in Arabidopsis is controlled by the 24- and 21-nt endogenous siRNAs analogous to Drosophila TE silencing by PIWI-interacting RNAs and siRNAs.
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Affiliation(s)
- Jian-Hua Zhao
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yuan-Yuan Fang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Cheng-Guo Duan
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Rong-Xiang Fang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Shou-Wei Ding
- Department of Plant Pathology and Microbiology, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521, USA
| | - Hui-Shan Guo
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
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14
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Lv DQ, Liu SW, Zhao JH, Zhou BJ, Wang SP, Guo HS, Fang YY. Replication of a pathogenic non-coding RNA increases DNA methylation in plants associated with a bromodomain-containing viroid-binding protein. Sci Rep 2016; 6:35751. [PMID: 27767195 PMCID: PMC5073342 DOI: 10.1038/srep35751] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 09/30/2016] [Indexed: 12/23/2022] Open
Abstract
Viroids are plant-pathogenic molecules made up of single-stranded circular non-coding RNAs. How replicating viroids interfere with host silencing remains largely unknown. In this study, we investigated the effects of a nuclear-replicating Potato spindle tuber viroid (PSTVd) on interference with plant RNA silencing. Using transient induction of silencing in GFP transgenic Nicotiana benthamiana plants (line 16c), we found that PSTVd replication accelerated GFP silencing and increased Virp1 mRNA, which encodes bromodomain-containing viroid-binding protein 1 and is required for PSTVd replication. DNA methylation was increased in the GFP transgene promoter of PSTVd-replicating plants, indicating involvement of transcriptional gene silencing. Consistently, accelerated GFP silencing and increased DNA methylation in the of GFP transgene promoter were detected in plants transiently expressing Virp1. Virp1 mRNA was also increased upon PSTVd infection in natural host potato plants. Reduced transcript levels of certain endogenous genes were also consistent with increases in DNA methylation in related gene promoters in PSTVd-infected potato plants. Together, our data demonstrate that PSTVd replication interferes with the nuclear silencing pathway in that host plant, and this is at least partially attributable to Virp1. This study provides new insights into the plant-viroid interaction on viroid pathogenicity by subverting the plant cell silencing machinery.
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MESH Headings
- DNA Methylation
- DNA, Plant/genetics
- DNA, Plant/metabolism
- Green Fluorescent Proteins/genetics
- Plant Diseases/genetics
- Plant Diseases/virology
- Plant Proteins/metabolism
- Plants, Genetically Modified
- Promoter Regions, Genetic
- RNA Interference
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Plant/genetics
- RNA, Plant/metabolism
- RNA, Untranslated/biosynthesis
- RNA, Viral/biosynthesis
- RNA-Binding Proteins/metabolism
- Solanum tuberosum/metabolism
- Solanum tuberosum/virology
- Nicotiana/genetics
- Nicotiana/metabolism
- Nicotiana/virology
- Viroids/genetics
- Viroids/pathogenicity
- Viroids/physiology
- Virus Replication/genetics
- Virus Replication/physiology
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Affiliation(s)
- Dian-Qiu Lv
- Virus-free Seedling Research Institute, Heilongjiang Academy of Agricultural Sciences, Harbin, China
- Heilongjiang Academy of Agricultural Sciences Postdoctoral Programme, Harbin, China
| | - Shang-Wu Liu
- Virus-free Seedling Research Institute, Heilongjiang Academy of Agricultural Sciences, Harbin, China
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jian-Hua Zhao
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Bang-Jun Zhou
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Shao-Peng Wang
- Virus-free Seedling Research Institute, Heilongjiang Academy of Agricultural Sciences, Harbin, China
| | - Hui-Shan Guo
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yuan-Yuan Fang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
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15
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Hadidi A, Flores R, Candresse T, Barba M. Next-Generation Sequencing and Genome Editing in Plant Virology. Front Microbiol 2016; 7:1325. [PMID: 27617007 PMCID: PMC4999435 DOI: 10.3389/fmicb.2016.01325] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 08/11/2016] [Indexed: 01/18/2023] Open
Abstract
Next-generation sequencing (NGS) has been applied to plant virology since 2009. NGS provides highly efficient, rapid, low cost DNA, or RNA high-throughput sequencing of the genomes of plant viruses and viroids and of the specific small RNAs generated during the infection process. These small RNAs, which cover frequently the whole genome of the infectious agent, are 21-24 nt long and are known as vsRNAs for viruses and vd-sRNAs for viroids. NGS has been used in a number of studies in plant virology including, but not limited to, discovery of novel viruses and viroids as well as detection and identification of those pathogens already known, analysis of genome diversity and evolution, and study of pathogen epidemiology. The genome engineering editing method, clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 system has been successfully used recently to engineer resistance to DNA geminiviruses (family, Geminiviridae) by targeting different viral genome sequences in infected Nicotiana benthamiana or Arabidopsis plants. The DNA viruses targeted include tomato yellow leaf curl virus and merremia mosaic virus (begomovirus); beet curly top virus and beet severe curly top virus (curtovirus); and bean yellow dwarf virus (mastrevirus). The technique has also been used against the RNA viruses zucchini yellow mosaic virus, papaya ringspot virus and turnip mosaic virus (potyvirus) and cucumber vein yellowing virus (ipomovirus, family, Potyviridae) by targeting the translation initiation genes eIF4E in cucumber or Arabidopsis plants. From these recent advances of major importance, it is expected that NGS and CRISPR-Cas technologies will play a significant role in the very near future in advancing the field of plant virology and connecting it with other related fields of biology.
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Affiliation(s)
- Ahmed Hadidi
- United States Department of Agriculture – Agricultural Research ServiceBeltsville, MD, USA
| | - Ricardo Flores
- Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia–Consejo Superior de Investigaciones CientíficasValencia, Spain
| | - Thierry Candresse
- UMR 1332 Biologie du Fruit et Pathologie, Institut National de la Recherche Agronomique, Université de BordeauxBordeaux, France
| | - Marina Barba
- Consiglio per la Ricerca in Agricoltura e l’analisi dell’Economia Agraria, Centro di Ricerca per la Patologia VegetaleRome, Italy
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16
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Zhao JH, Hua CL, Fang YY, Guo HS. The dual edge of RNA silencing suppressors in the virus–host interactions. Curr Opin Virol 2016; 17:39-44. [DOI: 10.1016/j.coviro.2015.12.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 12/19/2015] [Accepted: 12/28/2015] [Indexed: 02/02/2023]
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17
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Wang MB, Smith NA. Satellite RNA pathogens of plants: impacts and origins-an RNA silencing perspective. WILEY INTERDISCIPLINARY REVIEWS-RNA 2015; 7:5-16. [PMID: 26481458 DOI: 10.1002/wrna.1311] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 09/15/2015] [Accepted: 09/16/2015] [Indexed: 11/09/2022]
Abstract
Viral satellite RNAs (satRNAs) are among the smallest RNA pathogens in plants. They have little or no protein-coding capacity but can have a major impact on the host plants through trilateral interactions with helper viruses and host plants. Studies around the 1980s revealed much of what we know about satRNAs: they can affect helper virus accumulation, modulate helper virus-induced disease symptoms, and induce their own symptoms with the assistance of helper viruses which depend on specific nucleotide sequences of their genome and host species. The molecular basis of these satRNA-caused impacts and the origin of satRNAs have yet to be fully understood and revealed, but recent understanding of the antiviral RNA silencing pathways and advancement in RNA and DNA sequencing technologies have provided new avenues and opportunities to examine these unanswered questions. These RNA silencing-based studies have revealed the existence of cross silencing between some satRNAs and helper viruses, the downregulation of helper virus-encoded suppressor (VSR) of RNA silencing or inhibition/enhancement of VSR activity by satRNAs, the silencing of host-encoded genes by satRNA-derived small interfering RNA (siRNAs), and the presence of satRNA-like small RNAs in uninfected host plants. These findings have provided alternative RNA silencing-based models to explain the pathogenicity and origin of satRNAs. WIREs RNA 2016, 7:5-16. doi: 10.1002/wrna.1311 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Ming-Bo Wang
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) Agriculture Flagship, Canberra, ACT 2601, Australia
| | - Neil A Smith
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) Agriculture Flagship, Canberra, ACT 2601, Australia
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18
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Shimura H, Masuta C. Plant subviral RNAs as a long noncoding RNA (lncRNA): Analogy with animal lncRNAs in host-virus interactions. Virus Res 2015; 212:25-9. [PMID: 26116900 DOI: 10.1016/j.virusres.2015.06.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 06/17/2015] [Accepted: 06/17/2015] [Indexed: 12/16/2022]
Abstract
Satellite RNAs (satRNAs) and viroids belong to the group called subviral agents and are the smallest pathogens of plants. In general, small satRNAs and viroids are 300-400 nt in size and do not encode any functional proteins; they are thus regarded as so-called long noncoding RNAs (lncRNAs). These lncRNAs are receiving great attention as a new RNA class involved in gene regulation to control important biological processes such as gene transcription and epigenetic regulation. A substantial number of lncRNAs in animal cells have been found to play important roles in the interactions between a virus and its host. We here discuss the pathogenicity of subviral RNAs (especially satRNAs) in plant cells and their functions as lncRNAs associated with viral diseases, using animal lncRNAs as an analogy. Because, unlike animal lncRNAs, plant subviral RNAs can replicate and accumulate at very high levels in infected cells, we here considered the unique possibility that the RNA silencing machinery of plants, an important defense mechanism against virus infection, may have brought about the replication ability of subviral molecules. In addition, we also discuss the possibility that satRNAs may have arisen from plant-virus interactions in virus-infected cells. Understanding the molecular functions of these unique lncRNAs in plants will enable us to reveal the most plausible origins of these subviral RNAs.
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Affiliation(s)
- Hanako Shimura
- Graduate School of Agriculture, Hokkaido University, Kita-ku, Kita 9, Nishi 9, Sapporo 060-8589, Japan.
| | - Chikara Masuta
- Graduate School of Agriculture, Hokkaido University, Kita-ku, Kita 9, Nishi 9, Sapporo 060-8589, Japan.
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