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Impact of Exogenous Application of Potato Virus Y-Specific dsRNA on RNA Interference, Pattern-Triggered Immunity and Poly(ADP-ribose) Metabolism. Int J Mol Sci 2022; 23:ijms23147915. [PMID: 35887257 PMCID: PMC9317112 DOI: 10.3390/ijms23147915] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 07/13/2022] [Accepted: 07/15/2022] [Indexed: 02/06/2023] Open
Abstract
In this work we developed and exploited a spray-induced gene silencing (SIGS)-based approach to deliver double-stranded RNA (dsRNA), which was found to protect potato against potato virus Y (PVY) infection. Given that dsRNA can act as a defence-inducing signal that can trigger sequence-specific RNA interference (RNAi) and non-specific pattern-triggered immunity (PTI), we suspected that these two pathways may be invoked via exogeneous application of dsRNA, which may account for the alterations in PVY susceptibility in dsRNA-treated potato plants. Therefore, we tested the impact of exogenously applied PVY-derived dsRNA on both these layers of defence (RNAi and PTI) and explored its effect on accumulation of a homologous virus (PVY) and an unrelated virus (potato virus X, PVX). Here, we show that application of PVY dsRNA in potato plants induced accumulation of both small interfering RNAs (siRNAs), a hallmark of RNAi, and some PTI-related gene transcripts such as WRKY29 (WRKY transcription factor 29; molecular marker of PTI), RbohD (respiratory burst oxidase homolog D), EDS5 (enhanced disease susceptibility 5), SERK3 (somatic embryogenesis receptor kinase 3) encoding brassinosteroid-insensitive 1-associated receptor kinase 1 (BAK1), and PR-1b (pathogenesis-related gene 1b). With respect to virus infections, PVY dsRNA suppressed only PVY replication but did not exhibit any effect on PVX infection in spite of the induction of PTI-like effects in the presence of PVX. Given that RNAi-mediated antiviral immunity acts as the major virus resistance mechanism in plants, it can be suggested that dsRNA-based PTI alone may not be strong enough to suppress virus infection. In addition to RNAi- and PTI-inducing activities, we also showed that PVY-specific dsRNA is able to upregulate production of a key enzyme involved in poly(ADP-ribose) metabolism, namely poly(ADP-ribose) glycohydrolase (PARG), which is regarded as a positive regulator of biotic stress responses. These findings offer insights for future development of innovative approaches which could integrate dsRNA-induced RNAi, PTI and modulation of poly(ADP-ribose) metabolism in a co-ordinated manner, to ensure a high level of crop protection.
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Shameer K, Naika MB, Shafi KM, Sowdhamini R. Decoding systems biology of plant stress for sustainable agriculture development and optimized food production. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 145:19-39. [DOI: 10.1016/j.pbiomolbio.2018.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 10/23/2018] [Accepted: 12/06/2018] [Indexed: 12/13/2022]
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Lee TY, Kim CU, Bae EH, Seo SH, Jeong DG, Yoon SW, Chang KT, Kim YS, Kim SH, Kim DJ. Outer membrane vesicles harboring modified lipid A moiety augment the efficacy of an influenza vaccine exhibiting reduced endotoxicity in a mouse model. Vaccine 2016; 35:586-595. [PMID: 28024958 PMCID: PMC7115551 DOI: 10.1016/j.vaccine.2016.12.025] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 10/24/2016] [Accepted: 12/09/2016] [Indexed: 12/20/2022]
Abstract
Influenza is an acute respiratory disease and a major health problem worldwide. Since mucosal immunity plays a critical role in protection against influenza virus infection, mucosal immunization is considered a promising vaccination route. However, except for live-attenuated vaccines, there are no effective killed or recombinant mucosal influenza vaccines to date. Outer membrane vesicles (OMVs) are nano-sized vesicles produced by gram-negative bacteria, and contain various bacterial components capable of stimulating the immune system of the host. We generated an OMV with low endotoxicity (fmOMV) by modifying the structure of the lipid A moiety of lipopolysaccharide and investigated its effect as an intranasal vaccine adjuvant in an influenza vaccine model. In this model, fmOMV exhibited reduced toll-like receptor 4-stimulating activity and attenuated endotoxicity compared to that of native OMV. Intranasal injection of the vaccine antigen with fmOMV significantly increased systemic antibody and T cell responses, mucosal IgA levels, and the frequency of lung-resident influenza-specific T cells. In addition, the number of antigen-bearing CD103+ dendritic cells in the mediastinal lymph nodes was significantly increased after fmOMV co-administration. Notably, the mice co-immunized with fmOMV showed a significantly higher protection rate against challenge with a lethal dose of homologous or heterologous influenza viruses without adverse effects. These results show the potential of fmOMV as an effective mucosal adjuvant for intranasal vaccines.
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Affiliation(s)
- Tae-Young Lee
- Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, South Korea
| | - Chang-Ung Kim
- Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, South Korea; Department of Biochemistry, Chungnam National University, Daejeon, South Korea
| | - Eun-Hye Bae
- Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, South Korea
| | - Sang-Hwan Seo
- Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, South Korea
| | - Dae Gwin Jeong
- Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, South Korea; University of Science and Technology (UST), Daejeon, South Korea
| | - Sun-Woo Yoon
- Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, South Korea; University of Science and Technology (UST), Daejeon, South Korea
| | - Kyu-Tae Chang
- Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, South Korea
| | - Young Sang Kim
- Department of Biochemistry, Chungnam National University, Daejeon, South Korea
| | - Sang-Hyun Kim
- Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, South Korea.
| | - Doo-Jin Kim
- Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, South Korea; Department of Biochemistry, Chungnam National University, Daejeon, South Korea; University of Science and Technology (UST), Daejeon, South Korea.
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Krenz B, Bronikowski A, Lu X, Ziebell H, Thompson JR, Perry KL. Visual monitoring of Cucumber mosaic virus infection in Nicotiana benthamiana following transmission by the aphid vector Myzus persicae. J Gen Virol 2015; 96:2904-2912. [PMID: 25979730 DOI: 10.1099/vir.0.000185] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The single-stranded, positive-sense and tripartite RNA virus Cucumber mosaic virus (CMV) was used in this study as a method for monitoring the initial stages of virus infection following aphid transmission. The RNA2 of CMV was modified to incorporate, in a variety of arrangements, an open reading frame (ORF) encoding an enhanced green fluorescent protein (eGFP). The phenotypes of five engineered RNA2s were tested in Nicotiana tabacum, Nicotiana clevelandii and Nicotiana benthamiana. Only one construct (F4), in which the 2b ORF was truncated at the 3' end and fused in-frame with the eGFP ORF, was able to systemically infect N. benthamiana plants, express eGFP and be transmitted by the aphid Myzus persicae. The utility of this construct was demonstrated following infection as early as one day post-transmission (dpt) continuing through to systemic infection. Comparisons of the inoculation sites in different petiole sections one to three dpt clearly showed that the onset of infection and eGFP expression always occurred in the epidermal or collenchymatous tissue just below the epidermis; an observation consistent with the rapid time frame characteristic of the non-persistent mode of aphid transmission.
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Affiliation(s)
- Bjoern Krenz
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, 334 Plant Science Building, Ithaca, NY 14853-5904, USA
- Lehrstuhl Biochemie, Department Biologie - Universität Erlangen-Nürnberg, Staudtstrasse 5, 91058 Erlangen, Germany
| | - Agathe Bronikowski
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, 334 Plant Science Building, Ithaca, NY 14853-5904, USA
- Institute for Microbiology, Universität Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
| | - Xiaoyun Lu
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, 334 Plant Science Building, Ithaca, NY 14853-5904, USA
| | - Heiko Ziebell
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, 334 Plant Science Building, Ithaca, NY 14853-5904, USA
- Julius Kühn-Institut Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, 38104 Braunschweig, Germany
| | - Jeremy R Thompson
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, 334 Plant Science Building, Ithaca, NY 14853-5904, USA
| | - Keith L Perry
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, 334 Plant Science Building, Ithaca, NY 14853-5904, USA
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Li F, Huang C, Li Z, Zhou X. Suppression of RNA silencing by a plant DNA virus satellite requires a host calmodulin-like protein to repress RDR6 expression. PLoS Pathog 2014; 10:e1003921. [PMID: 24516387 PMCID: PMC3916407 DOI: 10.1371/journal.ppat.1003921] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 12/24/2013] [Indexed: 11/19/2022] Open
Abstract
In plants, RNA silencing plays a key role in antiviral defense. To counteract host defense, plant viruses encode viral suppressors of RNA silencing (VSRs) that target different effector molecules in the RNA silencing pathway. Evidence has shown that plants also encode endogenous suppressors of RNA silencing (ESRs) that function in proper regulation of RNA silencing. The possibility that these cellular proteins can be subverted by viruses to thwart host defense is intriguing but has not been fully explored. Here we report that the Nicotiana benthamiana calmodulin-like protein Nbrgs-CaM is required for the functions of the VSR βC1, the sole protein encoded by the DNA satellite associated with the geminivirus Tomato yellow leaf curl China virus (TYLCCNV). Nbrgs-CaM expression is up-regulated by the βC1. Transgenic plants over-expressing Nbrgs-CaM displayed developmental abnormities reminiscent of βC1-associated morphological alterations. Nbrgs-CaM suppressed RNA silencing in an Agrobacterium infiltration assay and, when over-expressed, blocked TYLCCNV-induced gene silencing. Genetic evidence showed that Nbrgs-CaM mediated the βC1 functions in silencing suppression and symptom modulation, and was required for efficient virus infection. Moreover, the tobacco and tomato orthologs of Nbrgs-CaM also possessed ESR activity, and were induced by betasatellite to promote virus infection in these Solanaceae hosts. We further demonstrated that βC1-induced Nbrgs-CaM suppressed the production of secondary siRNAs, likely through repressing RNA-DEPENDENT RNA POLYMERASE 6 (RDR6) expression. RDR6-deficient N. benthamiana plants were defective in antiviral response and were hypersensitive to TYLCCNV infection. More significantly, TYLCCNV could overcome host range restrictions to infect Arabidopsis thaliana when the plants carried a RDR6 mutation. These findings demonstrate a distinct mechanism of VSR for suppressing PTGS through usurpation of a host ESR, and highlight an essential role for RDR6 in RNA silencing defense response against geminivirus infection.
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Affiliation(s)
- Fangfang Li
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Changjun Huang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Zhenghe Li
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Xueping Zhou
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
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Shaw J, Love AJ, Makarova SS, Kalinina NO, Harrison BD, Taliansky ME. Coilin, the signature protein of Cajal bodies, differentially modulates the interactions of plants with viruses in widely different taxa. Nucleus 2014; 5:85-94. [PMID: 24637832 PMCID: PMC4028359 DOI: 10.4161/nucl.28315] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 02/18/2014] [Accepted: 02/21/2014] [Indexed: 12/28/2022] Open
Abstract
Cajal bodies (CBs) are distinct nuclear bodies physically and functionally associated with the nucleolus. In addition to their traditional function in coordinating maturation of certain nuclear RNAs, CBs participate in cell cycle regulation, development, and regulation of stress responses. A key "signature" component of CBs is coilin, the scaffolding protein essential for CB formation and function. Using an RNA silencing (loss-of-function) approach, we describe here new phenomena whereby coilin also affects, directly or indirectly, a variety of interactions between host plants and viruses that have RNA or DNA genomes. Moreover, the effects of coilin on these interactions are manifested differently: coilin contributes to plant defense against tobacco rattle virus (tobravirus), tomato black ring virus (nepovirus), barley stripe mosaic virus (hordeivirus), and tomato golden mosaic virus (begomovirus). In contrast, with potato virus Y (potyvirus) and turnip vein clearing virus (tobamovirus), coilin serves to increase virus pathogenicity. These findings show that interactions with coilin (or CBs) may involve diverse mechanisms with different viruses and that these mechanisms act at different phases of virus infection. Thus, coilin (CBs) has novel, unexpected natural functions that may be recruited or subverted by plant viruses for their own needs or, in contrast, are involved in plant defense mechanisms that suppress host susceptibility to the viruses.
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Affiliation(s)
- Jane Shaw
- Cell and Molecular Sciences; The James Hutton Institute; Dundee, UK
| | - Andrew J Love
- Cell and Molecular Sciences; The James Hutton Institute; Dundee, UK
| | - Svetlana S Makarova
- AN Belozersky Institute of Physico-Chemical Biology; Moscow State University; Moscow, Russia
| | - Natalia O Kalinina
- AN Belozersky Institute of Physico-Chemical Biology; Moscow State University; Moscow, Russia
| | - Bryan D Harrison
- Cell and Molecular Sciences; The James Hutton Institute; Dundee, UK
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Heinemann JA, Agapito-Tenfen SZ, Carman JA. A comparative evaluation of the regulation of GM crops or products containing dsRNA and suggested improvements to risk assessments. ENVIRONMENT INTERNATIONAL 2013; 55:43-55. [PMID: 23523853 DOI: 10.1016/j.envint.2013.02.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 02/08/2013] [Accepted: 02/22/2013] [Indexed: 05/20/2023]
Abstract
Changing the nature, kind and quantity of particular regulatory-RNA molecules through genetic engineering can create biosafety risks. While some genetically modified organisms (GMOs) are intended to produce new regulatory-RNA molecules, these may also arise in other GMOs not intended to express them. To characterise, assess and then mitigate the potential adverse effects arising from changes to RNA requires changing current approaches to food or environmental risk assessments of GMOs. We document risk assessment advice offered to government regulators in Australia, New Zealand and Brazil during official risk evaluations of GM plants for use as human food or for release into the environment (whether for field trials or commercial release), how the regulator considered those risks, and what that experience teaches us about the GMO risk assessment framework. We also suggest improvements to the process.
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Affiliation(s)
- Jack A Heinemann
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand.
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Simón-Mateo C, García JA. Antiviral strategies in plants based on RNA silencing. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1809:722-31. [PMID: 21652000 DOI: 10.1016/j.bbagrm.2011.05.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Revised: 05/17/2011] [Accepted: 05/18/2011] [Indexed: 01/25/2023]
Abstract
One of the challenges being faced in the twenty-first century is the biological control of plant viral infections. Among the different strategies to combat virus infections, those based on pathogen-derived resistance (PDR) are probably the most powerful approaches to confer virus resistance in plants. The application of the PDR concept not only revealed the existence of a previously unknown sequence-specific RNA-degradation mechanism in plants, but has also helped to design antiviral strategies to engineer viral resistant plants in the last 25 years. In this article, we review the different platforms related to RNA silencing that have been developed during this time to obtain plants resistant to viruses and illustrate examples of current applications of RNA silencing to protect crop plants against viral diseases of agronomic relevance. This article is part of a Special Issue entitled: MicroRNAs in viral gene regulation.
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Calvo M, Dujovny G, Lucini C, Ortuño J, Alamillo JM, Simón-Mateo C, López-Moya JJ, García JA. Constraints to virus infection in Nicotiana benthamiana plants transformed with a potyvirus amplicon. BMC PLANT BIOLOGY 2010; 10:139. [PMID: 20604920 PMCID: PMC3095287 DOI: 10.1186/1471-2229-10-139] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Accepted: 07/06/2010] [Indexed: 05/24/2023]
Abstract
BACKGROUND Plant genomes have been transformed with full-length cDNA copies of viral genomes, giving rise to what has been called 'amplicon' systems, trying to combine the genetic stability of transgenic plants with the elevated replication rate of plant viruses. However, amplicons' performance has been very variable regardless of the virus on which they are based. This has boosted further interest in understanding the underlying mechanisms that cause this behavior differences, and in developing strategies to control amplicon expression. RESULTS Nicotiana benthamiana plants were transformed with an amplicon consisting of a full-length cDNA of the potyvirus Plum pox virus (PPV) genome modified to include a GFP reporter gene. Amplicon expression exhibited a great variability among different transgenic lines and even among different plants of the same line. Plants of the line 10.6 initially developed without signs of amplicon expression, but at different times some of them started to display sporadic infection foci in leaves approaching maturity. The infection progressed systemically, but at later times the infected plants recovered and returned to an amplicon-inactive state. The failure to detect virus-specific siRNAs in 10.6 plants before amplicon induction and after recovery suggested that a strong amplicon-specific RNA silencing is not established in these plants. However, the coexpression of extra viral silencing suppressors caused some amplicon activation, suggesting that a low level of RNA silencing could be contributing to maintain amplicon repression in the 10.6 plants. The resistance mechanisms that prevent amplicon-derived virus infection were also active against exogenous PPV introduced by mechanical inoculation or grafting, but did not affect other viruses. Amplicon-derived PPV was able to spread into wild type scions grafted in 10.6 rootstocks that did not display signs of amplicon expression, suggesting that resistance has little effect on virus movement. CONCLUSIONS Our results suggest that amplicon-derived virus infection is limited in this particular transgenic line by a combination of factors, including the presumed low efficiency of the conversion from the transgene transcript to replicable viral RNA, and also by the activation of RNA silencing and other defensive responses of the plant, which are not completely neutralized by viral suppressors.
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Affiliation(s)
- María Calvo
- Centro Nacional de Biotecnología-CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Gabriela Dujovny
- Centro Nacional de Biotecnología-CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Cristina Lucini
- Centro Nacional de Biotecnología-CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Facultad de Ciencias y Artes, Universidad Católica de Ávila, Ávila, Spain
| | - Jesús Ortuño
- Centro Nacional de Biotecnología-CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Josefa M Alamillo
- Centro Nacional de Biotecnología-CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Departamento de Fisiología Vegetal, Facultad de Ciencias, Universidad de Córdoba, Córdoba, Spain
| | - Carmen Simón-Mateo
- Centro Nacional de Biotecnología-CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Juan José López-Moya
- Centro Nacional de Biotecnología-CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Centre for Research in Agricultural Genomics CRAG, CSIC-IRTA-UAB, Barcelona, Spain
| | - Juan Antonio García
- Centro Nacional de Biotecnología-CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
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Chichkova NV, Shaw J, Galiullina RA, Drury GE, Tuzhikov AI, Kim SH, Kalkum M, Hong TB, Gorshkova EN, Torrance L, Vartapetian AB, Taliansky M. Phytaspase, a relocalisable cell death promoting plant protease with caspase specificity. EMBO J 2010; 29:1149-61. [PMID: 20111004 PMCID: PMC2845272 DOI: 10.1038/emboj.2010.1] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Accepted: 01/04/2010] [Indexed: 01/28/2023] Open
Abstract
Caspases are cysteine-dependent proteases and are important components of animal apoptosis. They introduce specific breaks after aspartate residues in a number of cellular proteins mediating programmed cell death (PCD). Plants encode only distant homologues of caspases, the metacaspases that are involved in PCD, but do not possess caspase-specific proteolytic activity. Nevertheless, plants do display caspase-like activities indicating that enzymes structurally distinct from classical caspases may operate as caspase-like proteases. Here, we report the identification and characterisation of a novel PCD-related subtilisin-like protease from tobacco and rice named phytaspase (plant aspartate-specific protease) that possesses caspase specificity distinct from that of other known caspase-like proteases. We provide evidence that phytaspase is synthesised as a proenzyme, which is autocatalytically processed to generate the mature enzyme. Overexpression and silencing of the phytaspase gene showed that phytaspase is essential for PCD-related responses to tobacco mosaic virus and abiotic stresses. Phytaspase is constitutively secreted into the apoplast before PCD, but unexpectedly is re-imported into the cell during PCD providing insights into how phytaspase operates.
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Affiliation(s)
- Nina V Chichkova
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
| | - Jane Shaw
- Plant Pathology Programme, Scottish Crop Research Institute, Invergowrie, Dundee, UK
| | - Raisa A Galiullina
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
| | - Georgina E Drury
- Plant Pathology Programme, Scottish Crop Research Institute, Invergowrie, Dundee, UK
| | - Alexander I Tuzhikov
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
| | - Sang Hyon Kim
- Plant Pathology Programme, Scottish Crop Research Institute, Invergowrie, Dundee, UK
- Division of Biosciences and Bioinformatics, Myongji University, Yongin, Kyeongki-do, Korea
| | - Markus Kalkum
- Department of Immunology, Beckman Research Institute of the City of Hope, Duarte, CA, USA
| | - Teresa B Hong
- Department of Immunology, Beckman Research Institute of the City of Hope, Duarte, CA, USA
| | - Elena N Gorshkova
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
| | - Lesley Torrance
- Plant Pathology Programme, Scottish Crop Research Institute, Invergowrie, Dundee, UK
| | - Andrey B Vartapetian
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
| | - Michael Taliansky
- Plant Pathology Programme, Scottish Crop Research Institute, Invergowrie, Dundee, UK
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Endres MW, Gregory BD, Gao Z, Foreman AW, Mlotshwa S, Ge X, Pruss GJ, Ecker JR, Bowman LH, Vance V. Two plant viral suppressors of silencing require the ethylene-inducible host transcription factor RAV2 to block RNA silencing. PLoS Pathog 2010; 6:e1000729. [PMID: 20084269 PMCID: PMC2800190 DOI: 10.1371/journal.ppat.1000729] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Accepted: 12/15/2009] [Indexed: 12/11/2022] Open
Abstract
RNA silencing is a highly conserved pathway in the network of interconnected defense responses that are activated during viral infection. As a counter-defense, many plant viruses encode proteins that block silencing, often also interfering with endogenous small RNA pathways. However, the mechanism of action of viral suppressors is not well understood and the role of host factors in the process is just beginning to emerge. Here we report that the ethylene-inducible transcription factor RAV2 is required for suppression of RNA silencing by two unrelated plant viral proteins, potyvirus HC-Pro and carmovirus P38. Using a hairpin transgene silencing system, we find that both viral suppressors require RAV2 to block the activity of primary siRNAs, whereas suppression of transitive silencing is RAV2-independent. RAV2 is also required for many HC-Pro-mediated morphological anomalies in transgenic plants, but not for the associated defects in the microRNA pathway. Whole genome tiling microarray experiments demonstrate that expression of genes known to be required for silencing is unchanged in HC-Pro plants, whereas a striking number of genes involved in other biotic and abiotic stress responses are induced, many in a RAV2-dependent manner. Among the genes that require RAV2 for induction by HC-Pro are FRY1 and CML38, genes implicated as endogenous suppressors of silencing. These findings raise the intriguing possibility that HC-Pro-suppression of silencing is not caused by decreased expression of genes that are required for silencing, but instead, by induction of stress and defense responses, some components of which interfere with antiviral silencing. Furthermore, the observation that two unrelated viral suppressors require the activity of the same factor to block silencing suggests that RAV2 represents a control point that can be readily subverted by viruses to block antiviral silencing. RNA silencing is an important antiviral defense in plants, and many plant viruses encode proteins that block RNA silencing. However, the mechanism of action of the viral suppressors is complex, and little is known about the role of host plant proteins in the process. Here we report the first example of a host protein that plays a required role in viral suppression of silencing—a transcription factor called RAV2 that is required for suppression of silencing by two different and unrelated viral proteins. Analysis of plant gene expression patterns shows that RAV2 is required for induction of many genes involved in other stress and defense pathways, including genes implicated as plant suppressors of silencing. Overall, the results suggest that RAV2 is an important factor in viral suppression of silencing and that the role of RAV2 is to divert host defenses toward responses that interfere with antiviral silencing.
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Affiliation(s)
- Matthew W. Endres
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, United States of America
| | - Brian D. Gregory
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California, United States of America
- Genomic Analysis Laboratory, The Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Zhihuan Gao
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, United States of America
| | - Amy Wahba Foreman
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, United States of America
| | - Sizolwenkosi Mlotshwa
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, United States of America
| | - Xin Ge
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, United States of America
| | - Gail J. Pruss
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, United States of America
| | - Joseph R. Ecker
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California, United States of America
- Genomic Analysis Laboratory, The Salk Institute for Biological Studies, La Jolla, California, United States of America
- * E-mail: (JRE) (JE); (LHB) (LB); (VV) (VV)
| | - Lewis H. Bowman
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, United States of America
- * E-mail: (JRE) (JE); (LHB) (LB); (VV) (VV)
| | - Vicki Vance
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, United States of America
- * E-mail: (JRE) (JE); (LHB) (LB); (VV) (VV)
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Lewsey M, Surette M, Robertson FC, Ziebell H, Choi SH, Ryu KH, Canto T, Palukaitis P, Payne T, Walsh JA, Carr JP. The role of the Cucumber mosaic virus 2b protein in viral movement and symptom induction. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2009; 22:642-54. [PMID: 19445589 DOI: 10.1094/mpmi-22-6-0642] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The Cucumber mosaic virus (CMV) 2b protein is a counter-defense factor and symptom determinant. Conserved domains in the 2b protein sequence were mutated in the 2b gene of strain Fny-CMV. The effects of these mutations were assessed by infection of Nicotiana tabacum, N. benthamiana, and Arabidopsis thaliana (ecotype Col-0) with mutant viruses and by expression of mutant 2b transgenes in A. thaliana. We confirmed that two nuclear localization signals were required for symptom induction and found that the N-terminal domain was essential for symptom induction. The C-terminal domain and two serine residues within a putative phosphorylation domain modulated symptom severity. Further infection studies were conducted using Fny-CMVdelta2b, a mutant that cannot express the 2b protein and that induces no symptoms in N. tabacum, N. benthamiana, or A. thaliana ecotype Col-0. Surprisingly, in plants of A. thaliana ecotype C24, Fny-CMVdelta2b induced severe symptoms similar to those induced by the wild-type virus. However, C24 plants infected with the mutant virus recovered from disease while those infected with the wild-type virus did not. Expression of 2b transgenes from either Fny-CMV or from LS-CMV (a mild strain) in Col-0 plants enhanced systemic movement of Fny-CMVdelta2b and permitted symptom induction by Fny-CMVdelta2b. Taken together, the results indicate that the 2b protein itself is an important symptom determinant in certain hosts. However, they also suggest that the protein may somehow synergize symptom induction by other CMV-encoded factors.
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Affiliation(s)
- Mathew Lewsey
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
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Haupt S, Stroganova T, Ryabov E, Kim SH, Fraser G, Duncan G, Mayo MA, Barker H, Taliansky M. Nucleolar localization of potato leafroll virus capsid proteins. J Gen Virol 2005; 86:2891-2896. [PMID: 16186245 DOI: 10.1099/vir.0.81101-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Potato leafroll virus (PLRV) encodes two capsid proteins, major protein (CP) and minor protein (P5), an extended version of the CP produced by occasional translational 'readthrough' of the CP gene. Immunogold electron microscopy showed that PLRV CP is located in the cytoplasm and also localized in the nucleus, preferentially targeting the nucleolus. The nucleolar localization of PLRV CP was also confirmed when it was expressed as a fusion with green fluorescent protein (GFP) via an Agrobacterium vector. Mutational analysis identified a particular sequence within PLRV CP involved in nucleolar targeting [the nucleolar localization signal (NoLS)]. Minor protein P5 also contains the same NoLS, and was targeted to the nucleolus when it was expressed as a fusion with GFP from Agrobacterium. However, P5-GFP lost its nucleolar localization in the presence of replicating PLRV.
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Affiliation(s)
- Sophie Haupt
- University of Dundee, Dundee DD1 4NH, UK
- Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK
| | - Tanya Stroganova
- Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK
| | - Eugene Ryabov
- University of Warwick - HRI, Wellesbourne, Warwick CV35 9EF, UK
| | - Sang Hyon Kim
- Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK
| | - Gill Fraser
- Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK
| | - George Duncan
- Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK
| | - Mike A Mayo
- Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK
| | - Hugh Barker
- Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK
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Kobori T, Ryang BS, Natsuaki T, Kosaka Y. A New Technique to Select Mild Strains of Cucumber mosaic virus. PLANT DISEASE 2005; 89:879-882. [PMID: 30786521 DOI: 10.1094/pd-89-0879] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
An efficient technique to select a good attenuated virus to control Cucumber mosaic virus (CMV) disease was developed. Preliminary screenings were conducted to assess the virulence of virus recovered from dark-green islands and yellow tissues of mosaic leaves of Nicotiana rustica after co-inoculation with an attenuated mutant P2bR46C of CMV and its original severe isolate Pepo. All single-lesion isolates (SLIs) obtained from dark-green islands had the attenuated P2bR46C phenotype, but the SLIs from yellow tissue had either the virulent Pepo or the P2bR46C phenotype. When Pepo-infected N. rustica and tomato plants were grown at 15 or 36°C for 30 days, 17 of 288 SLIs obtained from the treated leaves elicited mosaic and dark-green spots without malformation. Dark-green tissue from each plant infected with 1 of these 17 SLIs then was used to inoculate one plant of N. rustica. All 17 plants had either very mild mosaic or no visible symptoms. One of these potential mild strains, 36R37, had an amino acid substitution on the 2b gene encoding the 2b protein. Isolate 36R37 also was highly cross-protective, and its symptom attenuation was stable for three serial host passages. After cold or heat treatment, the dark-green tissue proved to be a good source for isolating mild strains of the virus.
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Affiliation(s)
- Takashi Kobori
- Kyoto Prefectural Institute of Agricultural Biotechnology, Kyoto 619-0244, Japan
| | - Bo-Song Ryang
- Kyoto BIKEN Laboratories, Inc., Kyoto 611-0041, Japan
| | - Tomohide Natsuaki
- Genomics Research Institute, Utsunomiya University, Utsunomiya 321-8505, and Laboratory of Plant Pathology, Faculty of Agriculture, Utsunomiya University, Utsunomiya 321-8505, Japan
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Gu H, Ghabrial SA. The Bean pod mottle virus proteinase cofactor and putative helicase are symptom severity determinants. Virology 2005; 333:271-83. [PMID: 15721361 DOI: 10.1016/j.virol.2005.01.020] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2004] [Revised: 12/22/2004] [Accepted: 01/14/2005] [Indexed: 11/23/2022]
Abstract
Full-length infectious cDNA clones were constructed from the genomic RNAs of three distinct strains (K-G7, K-Ha1 and K-Ho1) of the comovirus Bean pod mottle virus (BPMV). Whereas K-G7, a subgroup I strain, and K-Ha1, a subgroup II strain produce mild mottling, the reassortant strain K-Ho1 (RNA1(I) + RNA2(II)) induces necrotic primary lesions on inoculated leaves of soybean and severe systemic leaf mottling and blistering. Pseudorecombinants of all possible combinations of transcripts were generated and tested for symptom production. Only soybean plants inoculated with combinations having RNA1 derived from the severe strain K-Ho1, regardless of the origin of RNA2, induced severe symptoms, indicating that symptom severity maps to RNA1. Experiments with chimeric RNA1 constructs indicated that the coding regions of the protease co-factor (Co-pro) and the C-terminal half of the putative helicase (Hel) are determinants of symptom severity. Symptom severity correlated well with higher accumulation of viral RNA, but neither the Co-pro nor Hel protein could be demonstrated as a suppressor of RNA silencing.
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Affiliation(s)
- Hongcang Gu
- Department of Plant Pathology, 201F Plant Science Building, 1405 Veterans Drive, University of Kentucky, Lexington, KY 40546-0312, USA
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Tairo F, Mukasa SB, Jones RAC, Kullaya A, Rubaihayo PR, Valkonen JPT. Unravelling the genetic diversity of the three main viruses involved in Sweet Potato Virus Disease (SPVD), and its practical implications. MOLECULAR PLANT PATHOLOGY 2005; 6:199-211. [PMID: 20565651 DOI: 10.1111/j.1364-3703.2005.00267.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
SUMMARY Sweetpotato (Ipomoea batatas) is a widely grown food crop, in which the most important diseases are caused by viruses. Genetic variability of three widely distributed sweetpotato viruses was analysed using data from 46 isolates of Sweet potato feathery mottle virus (SPFMV), 16 isolates of Sweet potato mild mottle virus (SPMMV) and 25 isolates of Sweet potato chlorotic stunt virus (SPCSV), of which 19, seven and six isolates, respectively, are newly characterized. Division of SPFMV into four genetic groups (strains) according to phylogenetic analysis of coat protein (CP) encoding sequences revealed that strain EA contained the East African isolates of SPFMV but none from elsewhere. In contrast, strain RC contained ten isolates from Australia, Africa, Asia and North America. Strain O contained six heterogeneous isolates from Africa, Asia and South America. The seven strain C isolates from Australia, Africa, Asia, and North and South America formed a group that was genetically distant from the other SPFMV strains. SPMMV isolates showed a high level of variability with no discrete strain groupings. SPCSV isolates from East Africa were phylogenetically distant to SPCSV isolates from elsewhere. Only from East Africa were adequate data available for different isolates of the three viruses to estimate the genetic variability of their local populations. The implications of the current sequence information and the need for more such information from most sweetpotato-growing regions of the world are discussed in relation to virus diagnostics and breeding for virus resistance.
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Affiliation(s)
- Fred Tairo
- Department of Plant Biology and Forest Genetics, Box 7080, SLU, SE-750 07 Uppsala, Sweden
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