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Jagram N, Dasgupta I. Principles and practice of virus induced gene silencing for functional genomics in plants. Virus Genes 2023; 59:173-187. [PMID: 36266497 DOI: 10.1007/s11262-022-01941-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 10/05/2022] [Indexed: 10/24/2022]
Abstract
Virus induced gene silencing (VIGS) has, of late, emerged as an important tool for transient silencing of genes in plants. This is now being increasingly used to determine functions of novel genes in a wide variety of plants, many of which are important crops yielding food and fiber or are sources of products having pharmaceutical uses. The technology for VIGS comprises the development of vectors derived from viruses, choosing the optimal orientation and size of the gene to be targeted and adopting the most suitable method of inoculation. This review gives a brief overview of the main aspects of VIGS technology as is being practiced. It also discusses the challenges the technology faces and the possible way ahead to improve its robustness, so that the technology finds wider applications.
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Affiliation(s)
- Neelam Jagram
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, 110021, India
| | - Indranil Dasgupta
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, 110021, India.
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2
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Virus-Induced Gene Silencing (VIGS): A Powerful Tool for Crop Improvement and Its Advancement towards Epigenetics. Int J Mol Sci 2023; 24:ijms24065608. [PMID: 36982682 PMCID: PMC10057534 DOI: 10.3390/ijms24065608] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 01/26/2023] [Accepted: 02/02/2023] [Indexed: 03/17/2023] Open
Abstract
Virus-induced gene silencing (VIGS) is an RNA-mediated reverse genetics technology that has evolved into an indispensable approach for analyzing the function of genes. It downregulates endogenous genes by utilizing the posttranscriptional gene silencing (PTGS) machinery of plants to prevent systemic viral infections. Based on recent advances, VIGS can now be used as a high-throughput tool that induces heritable epigenetic modifications in plants through the viral genome by transiently knocking down targeted gene expression. As a result of the progression of DNA methylation induced by VIGS, new stable genotypes with desired traits are being developed in plants. In plants, RNA-directed DNA methylation (RdDM) is a mechanism where epigenetic modifiers are guided to target loci by small RNAs, which play a major role in the silencing of the target gene. In this review, we described the molecular mechanisms of DNA and RNA-based viral vectors and the knowledge obtained through altering the genes in the studied plants that are not usually accessible to transgenic techniques. We showed how VIGS-induced gene silencing can be used to characterize transgenerational gene function(s) and altered epigenetic marks, which can improve future plant breeding programs.
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Epigenetic Changes Occurring in Plant Inbreeding. Int J Mol Sci 2023; 24:ijms24065407. [PMID: 36982483 PMCID: PMC10048984 DOI: 10.3390/ijms24065407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 03/01/2023] [Accepted: 03/10/2023] [Indexed: 03/18/2023] Open
Abstract
Inbreeding is the crossing of closely related individuals in nature or a plantation or self-pollinating plants, which produces plants with high homozygosity. This process can reduce genetic diversity in the offspring and decrease heterozygosity, whereas inbred depression (ID) can often reduce viability. Inbred depression is common in plants and animals and has played a significant role in evolution. In the review, we aim to show that inbreeding can, through the action of epigenetic mechanisms, affect gene expression, resulting in changes in the metabolism and phenotype of organisms. This is particularly important in plant breeding because epigenetic profiles can be linked to the deterioration or improvement of agriculturally important characteristics.
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Importin/exportin-mediated nucleocytoplasmic shuttling of cucumber mosaic virus 2b protein is required for 2b's efficient suppression of RNA silencing. PLoS Pathog 2022; 18:e1010267. [PMID: 35081172 PMCID: PMC8820599 DOI: 10.1371/journal.ppat.1010267] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 02/07/2022] [Accepted: 01/11/2022] [Indexed: 11/19/2022] Open
Abstract
The 2b protein (2b) of cucumber mosaic virus (CMV), an RNA-silencing suppressor (RSS), is a major pathogenicity determinant of CMV. 2b is localized in the nucleus and cytoplasm, and its nuclear import is determined by two nuclear localization signals (NLSs); a carrier protein (importin [IMPα]) is predicted to be involved in 2b's nuclear transport. Cytoplasmic 2bs play a role in suppression of RNA silencing by binding to small RNAs and AGO proteins. A putative nuclear export signal (NES) motif was also found in 2b, but has not been proved to function. Here, we identified a leucine-rich motif in 2b's C-terminal half as an NES. We then showed that NES-deficient 2b accumulated abundantly in the nucleus and lost its RSS activity, suggesting that 2b exported from the nucleus can play a role as an RSS. Although two serine residues (S40 and S42) were previously found to be phosphorylated, we also found that an additional phosphorylation site (S28) alone can affect 2b's nuclear localization and RSS activity. Alanine substitution at S28 impaired the IMPα-mediated nuclear/nucleolar localization of 2b, and RSS activity was even stronger compared to wild-type 2b. In a subcellular fractionation assay, phosphorylated 2bs were detected in the nucleus, and comparison of the accumulation levels of nuclear phospho-2b between wild-type 2b and the NES mutant showed a greatly reduced level of the phosphorylated NES mutant in the nucleus, suggesting that 2bs are dephosphorylated in the nucleus and may be translocated to the cytoplasm in a nonphosphorylated form. These results suggest that 2b manipulates its nucleocytoplasmic transport as if it tracks down its targets, small RNAs and AGOs, in the RNA silencing pathway. We infer that 2b's efficient RSS activity is maintained by a balance of phosphorylation and dephosphorylation, which are coupled to importin/exportin-mediated shuttling between the nucleus and cytoplasm.
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Abstract
With the increasing understanding of fundamentals of gene silencing pathways in plants, various tools and techniques for downregulating the expression of a target gene have been developed across multiple plant species. This chapter provides an insight into the molecular mechanisms of gene silencing and highlights the advancements in various gene silencing approaches. The prominent aspects of different gene silencing methods, their advantages and disadvantages have been discussed. A succinct discussion on the newly emerged microRNA-based technologies like microRNA-induced gene silencing (MIGS) and microRNA-mediated virus-induced gene silencing (MIR-VIGS) are also presented. We have also discussed the gene-editing system like CRISPR-Cas. The prominent bottlenecks in gene silencing methods are the off-target effects and lack of universal applicability. However, the tremendous growth in understanding of this field reflects the potentials for improvements in the currently available approaches and the development of new widely applicable methods for easy, fast, and efficient functional characterization of plant genes.
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Affiliation(s)
- Prachi Pandey
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India
| | - Kirankumar S Mysore
- Institute for Agricultural Biosciences, Oklahoma State University, Ardmore, OK, USA
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Fei Y, Pyott DE, Molnar A. Temperature modulates virus-induced transcriptional gene silencing via secondary small RNAs. THE NEW PHYTOLOGIST 2021; 232:356-371. [PMID: 34185326 DOI: 10.1111/nph.17586] [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: 05/25/2021] [Accepted: 06/17/2021] [Indexed: 05/08/2023]
Abstract
Virus-induced gene silencing (VIGS) can be harnessed to sequence-specifically degrade host transcripts and induce heritable epigenetic modifications referred to as virus-induced post-transcriptional gene silencing (ViPTGS) and virus-induced transcriptional gene silencing (ViTGS), respectively. Both ViPTGS and ViTGS enable manipulation of endogenous gene expression without the need for transgenesis. Although VIGS has been widely used in many plant species, it is not always uniform or highly efficient. The efficiency of VIGS is affected by developmental, physiological and environmental factors. Here, we use recombinant Tobacco rattle viruses (TRV) to study the effect of temperature on ViPTGS and ViTGS using GFP as a reporter gene of silencing in N. benthamiana 16c plants. We found that unlike ViPTGS, ViTGS was impaired at high temperature. Using a novel mismatch-small interfering RNA (siRNA) tool, which precisely distinguishes virus-derived (primary) from target-generated (secondary) siRNAs, we demonstrated that the lack of secondary siRNA production/amplification was responsible for inefficient ViTGS at 29°C. Moreover, inefficient ViTGS at 29°C inhibited the transmission of epigenetic gene silencing to the subsequent generations. Our finding contributes to understanding the impact of environmental conditions on primary and secondary siRNA production and may pave the way to design/optimize ViTGS for transgene-free crop improvement.
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Affiliation(s)
- Yue Fei
- Institute of Molecular Plant Sciences, University of Edinburgh, Max Born Crescent, Edinburgh, EH9 3BF, UK
| | - Douglas E Pyott
- Institute of Molecular Plant Sciences, University of Edinburgh, Max Born Crescent, Edinburgh, EH9 3BF, UK
| | - Attila Molnar
- Institute of Molecular Plant Sciences, University of Edinburgh, Max Born Crescent, Edinburgh, EH9 3BF, UK
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Han T, Wang F, Song Q, Ye W, Liu T, Wang L, Chen ZJ. An epigenetic basis of inbreeding depression in maize. SCIENCE ADVANCES 2021; 7:7/35/eabg5442. [PMID: 34452913 PMCID: PMC8397266 DOI: 10.1126/sciadv.abg5442] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 07/07/2021] [Indexed: 05/12/2023]
Abstract
Inbreeding depression is widespread across plant and animal kingdoms and may arise from the exposure of deleterious alleles and/or loss of overdominant alleles resulting from increased homozygosity, but these genetic models cannot fully explain the phenomenon. Here, we report epigenetic links to inbreeding depression in maize. Teosinte branched1/cycloidea/proliferating cell factor (TCP) transcription factors control plant development. During successive inbreeding among inbred lines, thousands of genomic regions across TCP-binding sites (TBS) are hypermethylated through the H3K9me2-mediated pathway. These hypermethylated regions are accompanied by decreased chromatin accessibility, increased levels of the repressive histone marks H3K27me2 and H3K27me3, and reduced binding affinity of maize TCP-proteins to TBS. Consequently, hundreds of TCP-target genes involved in mitochondrion, chloroplast, and ribosome functions are down-regulated, leading to reduced growth vigor. Conversely, random mating can reverse corresponding hypermethylation sites and TCP-target gene expression, restoring growth vigor. These results support a unique role of reversible epigenetic modifications in inbreeding depression.
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Affiliation(s)
- Tongwen Han
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Fang Wang
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Qingxin Song
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Wenxue Ye
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China
| | - Tieshan Liu
- Maize Research Institute, Shandong Academy of Agricultural Sciences, Jinan 250100, China
| | - Liming Wang
- Maize Research Institute, Shandong Academy of Agricultural Sciences, Jinan 250100, China
| | - Z Jeffrey Chen
- Department of Molecular Biosciences and Center for Computational Biology and Bioinformatics, The University of Texas at Austin, Austin, TX 78712, USA.
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Li S, Chen K, Grierson D. Molecular and Hormonal Mechanisms Regulating Fleshy Fruit Ripening. Cells 2021; 10:1136. [PMID: 34066675 PMCID: PMC8151651 DOI: 10.3390/cells10051136] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 05/03/2021] [Accepted: 05/05/2021] [Indexed: 12/17/2022] Open
Abstract
This article focuses on the molecular and hormonal mechanisms underlying the control of fleshy fruit ripening and quality. Recent research on tomato shows that ethylene, acting through transcription factors, is responsible for the initiation of tomato ripening. Several other hormones, including abscisic acid (ABA), jasmonic acid (JA) and brassinosteroids (BR), promote ripening by upregulating ethylene biosynthesis genes in different fruits. Changes to histone marks and DNA methylation are associated with the activation of ripening genes and are necessary for ripening initiation. Light, detected by different photoreceptors and operating through ELONGATED HYPOCOTYL 5(HY5), also modulates ripening. Re-evaluation of the roles of 'master regulators' indicates that MADS-RIN, NAC-NOR, Nor-like1 and other MADS and NAC genes, together with ethylene, promote the full expression of genes required for further ethylene synthesis and change in colour, flavour, texture and progression of ripening. Several different types of non-coding RNAs are involved in regulating expression of ripening genes, but further clarification of their diverse mechanisms of action is required. We discuss a model that integrates the main hormonal and genetic regulatory interactions governing the ripening of tomato fruit and consider variations in ripening regulatory circuits that operate in other fruits.
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Affiliation(s)
- Shan Li
- College of Agriculture & Biotechnology, Zijingang Campus, Zhejiang University, Hangzhou 310058, China;
| | - Kunsong Chen
- College of Agriculture & Biotechnology, Zijingang Campus, Zhejiang University, Hangzhou 310058, China;
- Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology, Zijingang Campus, Zhejiang University, Hangzhou 310058, China
| | - Donald Grierson
- College of Agriculture & Biotechnology, Zijingang Campus, Zhejiang University, Hangzhou 310058, China;
- Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology, Zijingang Campus, Zhejiang University, Hangzhou 310058, China
- Plant and Crop Sciences Division, School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough LE12 5RD, UK
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Atsumi G, Matsuo K, Fukuzawa N, Matsumura T. Virus-Mediated Targeted DNA Methylation Illuminates the Dynamics of Methylation in an Endogenous Plant Gene. Int J Mol Sci 2021; 22:4125. [PMID: 33923780 PMCID: PMC8073618 DOI: 10.3390/ijms22084125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 04/13/2021] [Accepted: 04/14/2021] [Indexed: 11/16/2022] Open
Abstract
DNA methylation maintains genome stability and regulates gene expression in plants. RNA-directed DNA methylation (RdDM) is critical for appropriate methylation. However, no efficient tools are available for the investigation of the functions of specific DNA methylation. In this study, the cucumber mosaic virus vector was used for targeted DNA methylation. Methylation was rapidly induced but gradually decreased from the 3' end of the target endogenous sequence in Nicotiana benthamiana, suggesting a mechanism to protect against the ectopic introduction of DNA methylation. Increasing 24-nt siRNAs blocked this reduction in methylation by down-regulating DCL2 and DCL4. RdDM relies on the sequence identity between RNA and genomic DNA; however, this identity does not appear to be the sole determinant for efficient DNA methylation. The current findings provide new insight into the regulation of DNA methylation and promote additional effort to develop efficient targeted DNA methylation in plants.
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Fei Y, Nyikó T, Molnar A. Non-perfectly matching small RNAs can induce stable and heritable epigenetic modifications and can be used as molecular markers to trace the origin and fate of silencing RNAs. Nucleic Acids Res 2021; 49:1900-1913. [PMID: 33524108 PMCID: PMC7913690 DOI: 10.1093/nar/gkab023] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 01/04/2021] [Accepted: 01/08/2021] [Indexed: 02/06/2023] Open
Abstract
Short non-coding RNA molecules (sRNAs) play a fundamental role in gene regulation and development in higher organisms. They act as molecular postcodes and guide AGO proteins to target nucleic acids. In plants, sRNA-targeted mRNAs are degraded, reducing gene expression. In contrast, sRNA-targeted DNA sequences undergo cytosine methylation referred to as RNA-directed DNA methylation (RdDM). Cytosine methylation can suppress transcription, thus sRNAs are potent regulators of gene expression. sRNA-mediated RdDM is involved in genome stability through transposon silencing, mobile signalling for epigenetic gene control and hybrid vigour. Since cytosine methylation can be passed on to subsequent generations, RdDM contributes to transgenerational inheritance of the epigenome. Using a novel approach, which can differentiate between primary (inducer) and secondary (amplified) sRNAs, we show that initiation of heritable RdDM does not require complete sequence complementarity between the sRNAs and their nuclear target sequences. sRNAs with up to four regularly interspaced mismatches are potent inducers of RdDM, however, the number and disruptive nature of nucleotide polymorphisms negatively correlate with their efficacy. Our findings contribute to understanding how sRNA can directly shape the epigenome and may be used in designing the next generation of RNA silencing constructs.
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Affiliation(s)
- Yue Fei
- University of Edinburgh, Institute of Molecular Plant Sciences, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Tünde Nyikó
- Agricultural Biotechnology Institute, Szent-Györgyi A. 4., Gödöllő 2100, Hungary
| | - Attila Molnar
- University of Edinburgh, Institute of Molecular Plant Sciences, Max Born Crescent, Edinburgh EH9 3BF, UK
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Sanan-Mishra N, Abdul Kader Jailani A, Mandal B, Mukherjee SK. Secondary siRNAs in Plants: Biosynthesis, Various Functions, and Applications in Virology. FRONTIERS IN PLANT SCIENCE 2021; 12:610283. [PMID: 33737942 PMCID: PMC7960677 DOI: 10.3389/fpls.2021.610283] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 01/18/2021] [Indexed: 05/13/2023]
Abstract
The major components of RNA silencing include both transitive and systemic small RNAs, which are technically called secondary sRNAs. Double-stranded RNAs trigger systemic silencing pathways to negatively regulate gene expression. The secondary siRNAs generated as a result of transitive silencing also play a substantial role in gene silencing especially in antiviral defense. In this review, we first describe the discovery and pathways of transitivity with emphasis on RNA-dependent RNA polymerases followed by description on the short range and systemic spread of silencing. We also provide an in-depth view on the various size classes of secondary siRNAs and their different roles in RNA silencing including their categorization based on their biogenesis. The other regulatory roles of secondary siRNAs in transgene silencing, virus-induced gene silencing, transitivity, and trans-species transfer have also been detailed. The possible implications and applications of systemic silencing and the different gene silencing tools developed are also described. The details on mobility and roles of secondary siRNAs derived from viral genome in plant defense against the respective viruses are presented. This entails the description of other compatible plant-virus interactions and the corresponding small RNAs that determine recovery from disease symptoms, exclusion of viruses from shoot meristems, and natural resistance. The last section presents an overview on the usefulness of RNA silencing for management of viral infections in crop plants.
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Affiliation(s)
- Neeti Sanan-Mishra
- Plant RNAi Biology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - A. Abdul Kader Jailani
- Plant RNAi Biology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
- Advanced Center for Plant Virology, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi, India
| | - Bikash Mandal
- Advanced Center for Plant Virology, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi, India
| | - Sunil K. Mukherjee
- Advanced Center for Plant Virology, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi, India
- *Correspondence: Sunil K. Mukherjee,
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Abstract
RNA-directed DNA methylation (RdDM) is a biological process in which non-coding RNA molecules direct the addition of DNA methylation to specific DNA sequences. The RdDM pathway is unique to plants, although other mechanisms of RNA-directed chromatin modification have also been described in fungi and animals. To date, the RdDM pathway is best characterized within angiosperms (flowering plants), and particularly within the model plant Arabidopsis thaliana. However, conserved RdDM pathway components and associated small RNAs (sRNAs) have also been found in other groups of plants, such as gymnosperms and ferns. The RdDM pathway closely resembles other sRNA pathways, particularly the highly conserved RNAi pathway found in fungi, plants, and animals. Both the RdDM and RNAi pathways produce sRNAs and involve conserved Argonaute, Dicer and RNA-dependent RNA polymerase proteins. RdDM has been implicated in a number of regulatory processes in plants. The DNA methylation added by RdDM is generally associated with transcriptional repression of the genetic sequences targeted by the pathway. Since DNA methylation patterns in plants are heritable, these changes can often be stably transmitted to progeny. As a result, one prominent role of RdDM is the stable, transgenerational suppression of transposable element (TE) activity. RdDM has also been linked to pathogen defense, abiotic stress responses, and the regulation of several key developmental transitions. Although the RdDM pathway has a number of important functions, RdDM-defective mutants in Arabidopsis thaliana are viable and can reproduce, which has enabled detailed genetic studies of the pathway. However, RdDM mutants can have a range of defects in different plant species, including lethality, altered reproductive phenotypes, TE upregulation and genome instability, and increased pathogen sensitivity. Overall, RdDM is an important pathway in plants that regulates a number of processes by establishing and reinforcing specific DNA methylation patterns, which can lead to transgenerational epigenetic effects on gene expression and phenotype.
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Khaing YY, Kobayashi Y, Takeshita M. The C-terminal region of the 2a protein and 2b protein of cucumber mosaic virus are involved in the induction of shoestring-like leaf blade in tomato. Virus Res 2020; 289:198172. [PMID: 32980403 DOI: 10.1016/j.virusres.2020.198172] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/18/2020] [Accepted: 09/18/2020] [Indexed: 11/28/2022]
Abstract
Cucumber mosaic virus (CMV) has numerous strains with distinct pathological properties in nature. In this study, we focused on the distinct host-specificity of two isolates of CMV regarding induction of the shoestring-like leaf blade (SLB) in tomato (Solanum lycopersicum cv. Sekaiichi). During the initial infection stage, plants inoculated with CMV-D8 and CMV-Y developed green/yellow systemic mosaic and stunting. Late in infection, CMV-D8 caused severe systemic symptoms with SLB on the newly emerged leaves, whereas CMY-Y caused severe yellow mosaic with stunting. Accumulation of viral RNA of CMV-D8 during initial infection was higher than for CMV-Y, but their levels did not differ significantly at 5 weeks post inoculation. Pseudorecombination and recombination analyses between CMV-D8 and CMV-Y genomic RNAs showed that recombinant that contained the C-terminal region of 2a and the entire 2b protein of CMV-D8 (D2a-C/D2b) induced SLB. Changing isoleucine to valine at position 830 in the 2a ORF played an important role in formation of chronic SLB. We further elucidated that infection with CMV-D8 or the recombinant Y1Y2(D2a-C/D2b)D3, but not with CMV-Y, upregulated miRNAs and transcript levels of AGO1, which is involved in RNA silencing, and of HD-ZIP, TCP4, and PHAN, which are essential for leaf morphogenesis. The present results first demonstrated that the cooperative function of D2a-C/D2b is involved indispensably in SLB formation. In addition, we suggest that D2a-C/D2b region interferes with the miRNA pathway that is associated with RNA silencing and leaf morphogenesis, leading to the enhanced virulence of CMV-D8.
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Affiliation(s)
- Yu Yu Khaing
- Laboratory of Plant Pathology, Faculty of Agriculture, Department of Agricultural and Environmental Sciences, University of Miyazaki, Gakuenkibanadainishi 1-1, Miyazaki 889-2192, Japan
| | - Yudai Kobayashi
- Laboratory of Plant Pathology, Faculty of Agriculture, Department of Agricultural and Environmental Sciences, University of Miyazaki, Gakuenkibanadainishi 1-1, Miyazaki 889-2192, Japan
| | - Minoru Takeshita
- Laboratory of Plant Pathology, Faculty of Agriculture, Department of Agricultural and Environmental Sciences, University of Miyazaki, Gakuenkibanadainishi 1-1, Miyazaki 889-2192, Japan.
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Yuan C, Li H, Qin C, Zhang X, Chen Q, Zhang P, Xu X, He M, Zhang X, Tör M, Xue D, Wang H, Jackson S, He Y, Liu Y, Shi N, Hong Y. Foxtail mosaic virus-induced flowering assays in monocot crops. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3012-3023. [PMID: 32061090 DOI: 10.1093/jxb/eraa080] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Accepted: 02/11/2020] [Indexed: 05/04/2023]
Abstract
Virus-induced flowering (VIF) exploits RNA or DNA viruses to express flowering time genes to induce flowering in plants. Such plant virus-based tools have recently attracted widespread attention for their fundamental and applied uses in flowering physiology and in accelerating breeding in dicotyledonous crops and woody fruit-trees. We now extend this technology to a monocot grass and a cereal crop. Using a Foxtail mosaic virus (FoMV)-based VIF system, dubbed FoMViF, we showed that expression of florigenic Flowering Locus T (FT) genes can promote early flowering and spikelet development in proso millet, a C4 grass species with potential as a nutritional food and biofuel resource, and in non-vernalized C3 wheat, a major food crop worldwide. Floral and spikelet/grain induction in the two monocot plants was caused by the virally expressed untagged or FLAG-tagged FT orthologs, and the florigenic activity of rice Hd3a was more pronounced than its dicotyledonous counterparts in proso millet. The FoMViF system is easy to use and its efficacy to induce flowering and early spikelet/grain production is high. In addition to proso millet and wheat, we envisage that FoMViF will be also applicable to many economically important monocotyledonous food and biofuel crops.
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Affiliation(s)
- Chen Yuan
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Hongmei Li
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Cheng Qin
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Xian Zhang
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Qianqian Chen
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Pengcheng Zhang
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Xiaorui Xu
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Meiling He
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Xinlian Zhang
- Department of Family Medicine and Public Health, Division of Biostatistics & Bioinformatics, University of California San Diego, La Jolla, CA, USA
| | - Mahmut Tör
- Worcester-Hangzhou Joint Molecular Plant Health Laboratory, School of Science and the Environment, University of Worcester, Worcester, UK
| | - Dawei Xue
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Huizhong Wang
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Stephen Jackson
- Warwick-Hangzhou RNA Signaling Joint Laboratory, School of Life Sciences, University of Warwick, Coventry, UK
| | - Yuehui He
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yule Liu
- Centre for Plant Biology and MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, China
| | - Nongnong Shi
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Yiguo Hong
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
- Worcester-Hangzhou Joint Molecular Plant Health Laboratory, School of Science and the Environment, University of Worcester, Worcester, UK
- Warwick-Hangzhou RNA Signaling Joint Laboratory, School of Life Sciences, University of Warwick, Coventry, UK
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15
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Dalakouras A, Papadopoulou KK. Epigenetic Modifications: An Unexplored Facet of Exogenous RNA Application in Plants. PLANTS 2020; 9:plants9060673. [PMID: 32466487 PMCID: PMC7356522 DOI: 10.3390/plants9060673] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 05/22/2020] [Accepted: 05/23/2020] [Indexed: 01/09/2023]
Abstract
Exogenous RNA interference (exo-RNAi) is a powerful transgene-free tool in modern crop improvement and protection platforms. In exo-RNAi approaches, double-stranded RNAs (dsRNAs) or short-interfering RNAs (siRNAs) are externally applied in plants in order to selectively trigger degradation of target mRNAs. Yet, the applied dsRNAs may also trigger unintended epigenetic alterations and result in epigenetically modified plants, an issue that has not been sufficiently addressed and which merits more careful consideration.
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Affiliation(s)
- Athanasios Dalakouras
- Department of Biochemistry & Biotechnology, University of Thessaly, 41500 Larissa, Greece;
- Institute of Plant Breeding and Genetic Resources ELGO-DEMETER, 57001 Thessaloniki, Greece
- Correspondence:
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16
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Pérez-Cañamás M, Hevia E, Hernández C. Epigenetic Changes in Host Ribosomal DNA Promoter Induced by an Asymptomatic Plant Virus Infection. BIOLOGY 2020; 9:biology9050091. [PMID: 32353984 PMCID: PMC7285159 DOI: 10.3390/biology9050091] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 04/25/2020] [Accepted: 04/26/2020] [Indexed: 11/16/2022]
Abstract
DNA cytosine methylation is one of the main epigenetic mechanisms in higher eukaryotes and is considered to play a key role in transcriptional gene silencing. In plants, cytosine methylation can occur in all sequence contexts (CG, CHG, and CHH), and its levels are controlled by multiple pathways, including de novo methylation, maintenance methylation, and demethylation. Modulation of DNA methylation represents a potentially robust mechanism to adjust gene expression following exposure to different stresses. However, the potential involvement of epigenetics in plant-virus interactions has been scarcely explored, especially with regard to RNA viruses. Here, we studied the impact of a symptomless viral infection on the epigenetic status of the host genome. We focused our attention on the interaction between Nicotiana benthamiana and Pelargonium line pattern virus (PLPV, family Tombusviridae), and analyzed cytosine methylation in the repetitive genomic element corresponding to ribosomal DNA (rDNA). Through a combination of bisulfite sequencing and RT-qPCR, we obtained data showing that PLPV infection gives rise to a reduction in methylation at CG sites of the rDNA promoter. Such a reduction correlated with an increase and decrease, respectively, in the expression levels of some key demethylases and of MET1, the DNA methyltransferase responsible for the maintenance of CG methylation. Hypomethylation of rDNA promoter was associated with a five-fold augmentation of rRNA precursor levels. The PLPV protein p37, reported as a suppressor of post-transcriptional gene silencing, did not lead to the same effects when expressed alone and, thus, it is unlikely to act as suppressor of transcriptional gene silencing. Collectively, the results suggest that PLPV infection as a whole is able to modulate host transcriptional activity through changes in the cytosine methylation pattern arising from misregulation of methyltransferases/demethylases balance.
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17
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Wang R, Angenent GC, Seymour G, de Maagd RA. Revisiting the Role of Master Regulators in Tomato Ripening. TRENDS IN PLANT SCIENCE 2020; 25:291-301. [PMID: 31926765 DOI: 10.1016/j.tplants.2019.11.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 11/14/2019] [Accepted: 11/18/2019] [Indexed: 05/19/2023]
Abstract
The study of transcriptional regulation of tomato ripening has been led by spontaneous mutations in transcription factor (TF) genes that completely inhibit normal ripening, suggesting that they are 'master regulators'. Studies using CRISPR/Cas9 mutagenesis to produce knockouts of the underlying genes indicate a different picture, suggesting that the regulation is more robust than previously thought. This requires us to revisit our model of the regulation of ripening and replace it with one involving a network of partially redundant components. At the same time, the fast rise of CRISPR/Cas mutagenesis, resulting in unexpectedly weak phenotypes, compared with knockdown technology, suggests that compensatory mechanisms may obscure protein functions. This emphasises the need for assessment of these mechanisms in plants and for the careful design of mutagenesis experiments.
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Affiliation(s)
- Rufang Wang
- Laboratory of Molecular Biology, Wageningen University & Research, Wageningen, The Netherlands
| | - Gerco C Angenent
- Laboratory of Molecular Biology, Wageningen University & Research, Wageningen, The Netherlands; Bioscience, Wageningen University & Research, Wageningen, The Netherlands
| | - Graham Seymour
- School of Biosciences, University of Nottingham, Sutton Bonington, Loughborough, UK
| | - Ruud A de Maagd
- Bioscience, Wageningen University & Research, Wageningen, The Netherlands.
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18
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Ezawa T, Maruyama H, Kikuchi Y, Yokoyama K, Masuta C. Application of Virus-Induced Gene Silencing to Arbuscular Mycorrhizal Fungi. Methods Mol Biol 2020; 2146:249-254. [PMID: 32415609 DOI: 10.1007/978-1-0716-0603-2_19] [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: 06/11/2023]
Abstract
Downregulation of AM fungal genes using a plant viral vector is feasible. A partial sequence of a target fungal gene is cloned into the multicloning site of CMV2-A1 vector developed from RNA2 of Cucumber mosaic virus Y strain, and the RNA2, together with RNA1 and RNA3 of the virus, are in vitro-transcribed. Inoculation of Nicotiana benthamiana with these viral RNAs results in reconstitution of the virus in the plant, which triggers silencing of the fungal gene. Here, we describe not only the methods but also several tips for successful application of virus-induced gene silencing to AM fungi.
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Affiliation(s)
- Tatsuhiro Ezawa
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan.
| | - Hayato Maruyama
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Yusuke Kikuchi
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Kaede Yokoyama
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Chikara Masuta
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
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Li C, Hirano H, Kasajima I, Yamagishi N, Yoshikawa N. Virus-induced gene silencing in chili pepper by apple latent spherical virus vector. J Virol Methods 2019; 273:113711. [PMID: 31404574 DOI: 10.1016/j.jviromet.2019.113711] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 07/01/2019] [Accepted: 07/25/2019] [Indexed: 12/30/2022]
Abstract
Apple latent spherical virus (ALSV) can infect a variety of crops, usually without inducing symptoms. Partial gene sequences can be introduced into ALSV vectors for the induction of virus-induced gene silencing (VIGS). These features are beneficial for the estimation of gene functions in plants, with relatively concise experimental manipulations. Given that the infectability of chili peppers (Capsicum spp.) by ALSV was unknown, an ALSV infectivity test was performed on the highly pungent Capsicum chinense cultivar 'Habanero'. The chili pepper plants were not infected after rub-inoculation with a crude homogenate of ALSV-infected Chenopodium quinoa leaves, whereas inoculating them with a concentrated ALSV virus preparation caused an infection. Inoculation with an ALSV RNA preparation by gold particle bombardment resulted in high infection rates (about 90%). The infection was systemic and the infected plants were symptomless. For the induction of VIGS, 201-nucleotide fragments of the putative aminotransferase (pAMT) gene were introduced into the ALSV vector. These ALSV vectors infected 80-90% of RNA-inoculated chili pepper seedlings. Expression of pAMT-mRNA was repressed in the placenta of immature fruit of infected plants. The silencing of pAMT in the infected plants caused a substantial decrease in capsaicin content and a concomitant moderate accumulation of the non-pungent bioactive metabolite capsiate in these plants. These results showed that ALSV could be used to study gene functions by VIGS and to enhance capsiate accumulation in chili pepper through genetic modification.
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Affiliation(s)
- Chunjiang Li
- Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Hiroto Hirano
- Frontier Research Laboratories, Institute for Innovation, Ajinomoto Co., Inc., Kawasaki, Kanagawa 210-8681, Japan
| | - Ichiro Kasajima
- Agri-Innovation Center, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Noriko Yamagishi
- Agri-Innovation Center, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Nobuyuki Yoshikawa
- Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan; Agri-Innovation Center, Iwate University, Morioka, Iwate 020-8550, Japan.
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20
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Matsunaga W, Shimura H, Shirakawa S, Isoda R, Inukai T, Matsumura T, Masuta C. Transcriptional silencing of 35S driven-transgene is differentially determined depending on promoter methylation heterogeneity at specific cytosines in both plus- and minus-sense strands. BMC PLANT BIOLOGY 2019; 19:24. [PMID: 30642254 PMCID: PMC6332629 DOI: 10.1186/s12870-019-1628-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 01/02/2019] [Indexed: 05/18/2023]
Abstract
BACKGROUND De novo DNA methylation triggered by short interfering RNAs is called RNA-directed DNA methylation (RdDM). Transcriptional gene silencing (TGS) through RdDM can be induced using a viral vector. We have previously induced RdDM on the 35S promoter in the green fluorescent protein (GFP)-expressing Nicotiana benthamiana line 16c using the cucumber mosaic virus vector. The GFP fluorescence phenotype segregated into two types, "red" and "orange" in the first self-fertilized (S1) progeny plants by the difference in degree of recovery from TGS on GFP expression. In the second self-fertilized generation (S2 plants), the phenotypes again segregated. Explaining what generates the red and orange types could answer a very important question in epigenetics: How is the robustness of TGS maintained after RdDM induction? RESULTS In bisulfite sequencing analyses, we found a significant difference in the overall promoter hypermethylation pattern between the red and orange types in S1 plants but little difference in S2 plants. Therefore, we assumed that methylation at some specific cytosine residues might be important in determining the two phenotypes. To find the factor that discriminates stable, robust TGS from the unstable TGS with incomplete inheritance, we analyzed the direct effect of methylated cytosine residues on TGS. Because it has not yet been demonstrated that DNA methylation at a few specific cytosine residues on known sequence elements can indeed determine TGS robustness, we newly developed a method by which we can directly evaluate the effect of specific methylation on promoter activity. In this assay, we found that the effects of the specific cytosine methylation on TGS differed between the plus- and minus-strands. CONCLUSIONS We found two distinct phenotypes, the stable and unstable TGS in the progenies of virus-induced TGS plants. Our bisulfite sequencing analyses suggested that methylation at some specific cytosine residues in the 35S promoter played a role in determining whether stable or unstable TGSs are induced. Using the developed method, we inferred that DNA methylation heterogeneity in and between the plus- and minus-strands can differentially determine TGS.
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Affiliation(s)
- Wataru Matsunaga
- Research Faculty of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo, 060-8589 Japan
| | - Hanako Shimura
- Research Faculty of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo, 060-8589 Japan
| | - Senri Shirakawa
- Research Faculty of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo, 060-8589 Japan
| | - Reika Isoda
- Research Faculty of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo, 060-8589 Japan
| | - Tsuyoshi Inukai
- Research Faculty of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo, 060-8589 Japan
| | - Takeshi Matsumura
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo, 062-8517 Japan
| | - Chikara Masuta
- Research Faculty of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo, 060-8589 Japan
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Rothan C, Diouf I, Causse M. Trait discovery and editing in tomato. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 97:73-90. [PMID: 30417464 DOI: 10.1111/tpj.14152] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 10/08/2018] [Accepted: 10/30/2018] [Indexed: 06/09/2023]
Abstract
Tomato (Solanum lycopersicum), which is used for both processing and fresh markets, is a major crop species that is the top ranked vegetable produced over the world. Tomato is also a model species for research in genetics, fruit development and disease resistance. Genetic resources available in public repositories comprise the 12 wild related species and thousands of landraces, modern cultivars and mutants. In addition, high quality genome sequences are available for cultivated tomato and for several wild relatives, hundreds of accessions have been sequenced, and databases gathering sequence data together with genetic and phenotypic data are accessible to the tomato community. Major breeding goals are productivity, resistance to biotic and abiotic stresses, and fruit sensorial and nutritional quality. New traits, including resistance to various biotic and abiotic stresses and root architecture, are increasingly being studied. Several major mutations and quantitative trait loci (QTLs) underlying traits of interest in tomato have been uncovered to date and, thanks to new populations and advances in sequencing technologies, the pace of trait discovery has considerably accelerated. In recent years, clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 gene editing (GE) already proved its remarkable efficiency in tomato for engineering favorable alleles and for creating new genetic diversity by gene disruption, gene replacement, and precise base editing. Here, we provide insight into the major tomato traits and underlying causal genetic variations discovered so far and review the existing genetic resources and most recent strategies for trait discovery in tomato. Furthermore, we explore the opportunities offered by CRISPR/Cas9 and their exploitation for trait editing in tomato.
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Affiliation(s)
- Christophe Rothan
- INRA and University of Bordeaux, UMR 1332 Biologie du Fruit et Pathologie, F-33140, Villenave d'Ornon, France
| | - Isidore Diouf
- INRA, UR1052, Génétique et Amélioration des Fruits et Légumes, CS60094, F-84143, Montfavet, France
| | - Mathilde Causse
- INRA, UR1052, Génétique et Amélioration des Fruits et Légumes, CS60094, F-84143, Montfavet, France
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22
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Wakasa Y, Kawakatsu T, Harada T, Takaiwa F. Transgene-independent heredity of RdDM-mediated transcriptional gene silencing of endogenous genes in rice. PLANT BIOTECHNOLOGY JOURNAL 2018; 16:2007-2015. [PMID: 29704881 PMCID: PMC6230945 DOI: 10.1111/pbi.12934] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 03/27/2018] [Accepted: 04/03/2018] [Indexed: 05/05/2023]
Abstract
To induce transcriptional gene silencing (TGS) of endogenous genes of rice (Oryza sativa L.), we expressed double-strand RNA of each promoter region and thus induced RNA-directed DNA methylation (RdDM). We targeted constitutively expressed genes encoding calnexin (CNX), protein disulphide isomerase (PDIL1-1) and luminal binding protein (BiP1); an endoplasmic reticulum stress-inducible gene (OsbZIP50); and genes with seed-specific expression encoding α-globulin (Glb-1) and glutelin-B4 (GluB4). TGS of four genes was obtained with high efficiency (CNX, 66.7% of regenerated plants; OsBiP1, 67.4%; OsbZIP50, 63.4%; GluB4, 66.1%), whereas the efficiency was lower for PDIL1-1 (33.3%) and Glb-1 TGS lines (10.5%). The heredity of TGS, methylation levels of promoter regions and specificity of silencing of the target gene were investigated in some of the TGS lines. In progeny of CNX and OsbZIP50 TGS lines, suppression of the target genes was preserved (except in the endosperm) even after the removal of trigger genes (T-DNA) by segregation. TGS of CNX was reverted by demethylation treatment, and a significant difference in CG and CHG methylation levels in the -1 to -250 bp region of the CNX promoter was detected between the TGS and revertant lines, suggesting that TGS is closely related to the methylation levels of promoter. TGS exhibited specific suppression towards the target gene compared with post-transcriptional gene silencing when GluB4 gene from glutelin multigene family was targeted. Based on these results, future perspectives and problems to be solved in the application of RdDM to new plant breeding techniques in rice are discussed.
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Affiliation(s)
- Yuhya Wakasa
- Plant Molecular Farming UnitInstitute of Agrobiological SciencesNational Agriculture and Food Research OrganizationTsukubaJapan
| | - Taiji Kawakatsu
- Plant Molecular Farming UnitInstitute of Agrobiological SciencesNational Agriculture and Food Research OrganizationTsukubaJapan
| | - Takeo Harada
- Faculty of Agriculture and Life ScienceHirosaki UniversityHirosakiJapan
| | - Fumio Takaiwa
- Plant Molecular Farming UnitInstitute of Agrobiological SciencesNational Agriculture and Food Research OrganizationTsukubaJapan
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23
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Jeon EJ, Tadamura K, Murakami T, Inaba JI, Kim BM, Sato M, Atsumi G, Kuchitsu K, Masuta C, Nakahara KS. rgs-CaM Detects and Counteracts Viral RNA Silencing Suppressors in Plant Immune Priming. J Virol 2017; 91:e00761-17. [PMID: 28724770 PMCID: PMC5599751 DOI: 10.1128/jvi.00761-17] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 07/13/2017] [Indexed: 01/13/2023] Open
Abstract
Primary infection of a plant with a pathogen that causes high accumulation of salicylic acid in the plant typically via a hypersensitive response confers enhanced resistance against secondary infection with a broad spectrum of pathogens, including viruses. This phenomenon is called systemic acquired resistance (SAR), which is a plant priming for adaption to repeated biotic stress. However, the molecular mechanisms of SAR-mediated enhanced inhibition, especially of virus infection, remain unclear. Here, we show that SAR against cucumber mosaic virus (CMV) in tobacco plants (Nicotiana tabacum) involves a calmodulin-like protein, rgs-CaM. We previously reported the antiviral function of rgs-CaM, which binds to and directs degradation of viral RNA silencing suppressors (RSSs), including CMV 2b, via autophagy. We found that rgs-CaM-mediated immunity is ineffective against CMV infection in normally growing tobacco plants but is activated as a result of SAR induction via salicylic acid signaling. We then analyzed the effect of overexpression of rgs-CaM on salicylic acid signaling. Overexpressed and ectopically expressed rgs-CaM induced defense reactions, including cell death, generation of reactive oxygen species, and salicylic acid signaling. Further analysis using a combination of the salicylic acid analogue benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) and the Ca2+ ionophore A23187 revealed that rgs-CaM functions as an immune receptor that induces salicylic acid signaling by simultaneously perceiving both viral RSS and Ca2+ influx as infection cues, implying its autoactivation. Thus, secondary infection of SAR-induced tobacco plants with CMV seems to be effectively inhibited through 2b recognition and degradation by rgs-CaM, leading to reinforcement of antiviral RNA silencing and other salicylic acid-mediated antiviral responses.IMPORTANCE Even without an acquired immune system like that in vertebrates, plants show enhanced whole-plant resistance against secondary infection with pathogens; this so-called systemic acquired resistance (SAR) has been known for more than half a century and continues to be extensively studied. SAR-induced plants strongly and rapidly express a number of antibiotics and pathogenesis-related proteins targeted against secondary infection, which can account for enhanced resistance against bacterial and fungal pathogens but are not thought to control viral infection. This study showed that enhanced resistance against cucumber mosaic virus is caused by a tobacco calmodulin-like protein, rgs-CaM, which detects and counteracts the major viral virulence factor (RNA silencing suppressor) after SAR induction. rgs-CaM-mediated SAR illustrates the growth versus defense trade-off in plants, as it targets the major virulence factor only under specific biotic stress conditions, thus avoiding the cost of constitutive activation while reducing the damage from virus infection.
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Affiliation(s)
- Eun Jin Jeon
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Kazuki Tadamura
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Taiki Murakami
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Jun-Ichi Inaba
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Bo Min Kim
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Masako Sato
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Go Atsumi
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Kazuyuki Kuchitsu
- Department of Applied Biological Science and Research Institute for Science and Technology, Tokyo University of Science, Noda, Chiba, Japan
| | - Chikara Masuta
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Kenji S Nakahara
- Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
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24
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Correction. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 90:1208-1211. [PMID: 28585412 DOI: 10.1111/tpj.13562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
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25
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Groszyk J, Kowalczyk M, Yanushevska Y, Stochmal A, Rakoczy-Trojanowska M, Orczyk W. Identification and VIGS-based characterization of Bx1 ortholog in rye (Secale cereale L.). PLoS One 2017; 12:e0171506. [PMID: 28234909 PMCID: PMC5325281 DOI: 10.1371/journal.pone.0171506] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 01/21/2017] [Indexed: 12/28/2022] Open
Abstract
The first step of the benzoxazinoid (BX) synthesis pathway is catalyzed by an enzyme with indole-3-glycerol phosphate lyase activity encoded by 3 genes, Bx1, TSA and Igl. A gene highly homologous to maize and wheat Bx1 has been identified in rye. The goal of the study was to analyze the gene and to experimentally verify its role in the rye BX biosynthesis pathway as a rye ortholog of the Bx1 gene. Expression of the gene showed peak values 3 days after imbibition (dai) and at 21 dai it was undetectable. Changes of the BX content in leaves were highly correlated with the expression pattern until 21 dai. In plants older than 21 dai despite the undetectable expression of the analyzed gene there was still low accumulation of BXs. Function of the gene was verified by correlating its native expression and virus-induced silencing with BX accumulation. Barley stripe mosaic virus (BSMV)-based vectors were used to induce transcriptional (TGS) and posttranscriptional (PTGS) silencing of the analyzed gene. Both strategies (PTGS and TGS) significantly reduced the transcript level of the analyzed gene, and this was highly correlated with lowered BX content. Inoculation with virus-based vectors specifically induced expression of the analyzed gene, indicating up-regulation by biotic stressors. This is the first report of using the BSMV-based system for functional analysis of rye gene. The findings prove that the analyzed gene is a rye ortholog of the Bx1 gene. Its expression is developmentally regulated and is strongly induced by biotic stress. Stable accumulation of BXs in plants older than 21 dai associated with undetectable expression of ScBx1 indicates that the function of the ScBx1 in the BX biosynthesis is redundant with another gene. We anticipate that the unknown gene is a putative ortholog of the Igl, which still remains to be identified in rye.
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Affiliation(s)
- Jolanta Groszyk
- Department of Genetic Engineering, Plant Breeding and Acclimatization Institute – National Research Institute, Blonie, Poland
| | - Mariusz Kowalczyk
- Department of Biochemistry and Crop Quality, Institute of Soil Science and Plant Cultivation State Research Institute, Pulawy, Poland
| | - Yuliya Yanushevska
- Department of Genetic Engineering, Plant Breeding and Acclimatization Institute – National Research Institute, Blonie, Poland
| | - Anna Stochmal
- Department of Biochemistry and Crop Quality, Institute of Soil Science and Plant Cultivation State Research Institute, Pulawy, Poland
| | - Monika Rakoczy-Trojanowska
- Department of Plant Genetics, Breeding and Biotechnology, Warsaw University of Life Sciences, Warsaw, Poland
| | - Waclaw Orczyk
- Department of Genetic Engineering, Plant Breeding and Acclimatization Institute – National Research Institute, Blonie, Poland
- * E-mail:
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26
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Tasaki K, Terada H, Masuta C, Yamagishi M. Virus-induced gene silencing (VIGS) in Lilium leichtlinii using the Cucumber mosaic virus vector. PLANT BIOTECHNOLOGY (TOKYO, JAPAN) 2016; 33:373-381. [PMID: 31274998 PMCID: PMC6587034 DOI: 10.5511/plantbiotechnology.16.1018a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 10/18/2016] [Indexed: 05/08/2023]
Abstract
Lilies (Lilium) are among the most important floriculture crops, and to accelerate research regarding lily genetics, the development of reverse-genetics tools is necessary. However, Agrobacterium-mediated transformation in Lilium is time-consuming, since the plants require several years to progress from acclimation to flowering. Thus, virus-induced gene silencing (VIGS) is an attractive method for assaying gene function. In the present study, we modified a lily-derived strain of Cucumber mosaic virus (CMV-HL) as a VIGS vector and evaluated its effectiveness for inducing gene silencing in Lilium leichtlinii by introducing L. leichtlinii phytoene desaturase (LlPDS) gene fragments into an intercistronic region between the 3a and 3b genes of the CMV-HL RNA3 genome. At 30 days after inoculation (dpi) with LlPDS-containing CMV-HL, photo-bleaching was observed in the upper leaves of L. leichtlinii, and at 57 dpi, we observed that the natural orange color in flower tepals had faded. Reduced LlPDS expression and the detection of small interfering LlPDS RNA indicated that the color changes were the result of LlPDS gene silencing. In addition, the leaves also exhibited a mild photo-bleaching phenotype in the following year. Therefore, our results indicate that CMV-HL spreads systemically in the leaves and flowers of Lilium during the first year of infection, as well as in new shoots during the following year, and that the vector system can be successfully applied to induce short-term endogenous gene silencing in lilies.
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Affiliation(s)
- Keisuke Tasaki
- Research Faculty of Agriculture, Hokkaido University, N9W9, Kita-ku, Sapporo, Hokkaido 060-8589, Japan
| | - Hiroyuki Terada
- Graduate School of Agriculture, Hokkaido University, N9W9, Kita-ku, Sapporo, Hokkaido 060-8589, Japan
| | - Chikara Masuta
- Research Faculty of Agriculture, Hokkaido University, N9W9, Kita-ku, Sapporo, Hokkaido 060-8589, Japan
| | - Masumi Yamagishi
- Research Faculty of Agriculture, Hokkaido University, N9W9, Kita-ku, Sapporo, Hokkaido 060-8589, Japan
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Ju Z, Wang L, Cao D, Zuo J, Zhu H, Fu D, Luo Y, Zhu B. A viral satellite DNA vector-induced transcriptional gene silencing via DNA methylation of gene promoter in Nicotiana benthamiana. Virus Res 2016; 223:99-107. [PMID: 27422476 DOI: 10.1016/j.virusres.2016.07.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 07/05/2016] [Accepted: 07/08/2016] [Indexed: 11/19/2022]
Abstract
Virus-induced gene silencing (VIGS) has been widely used for plant functional genomics study at the post-transcriptional level using various DNA or RNA viral vectors. However, while virus-induced transcriptional gene silencing (VITGS) via DNA methylation of gene promoter was achieved using several plant RNA viral vectors, it has not yet been done using a satellite DNA viral vector. In this study, a viral satellite DNA associated with tomato yellow leaf curl China virus (TYLCCNV), which has been modified as a VIGS vector in previous research, was developed as a VITGS vector. Firstly, the viral satellite DNA VIGS vector was further optimized to a more convenient p1.7A+2mβ vector with high silencing efficiency of the phytoene desaturase (PDS) gene in Nicotiana benthamiana plants. Secondly, the constructed VITGS vector (TYLCCNV:35S), which carried a portion of the cauliflower mosaic virus 35S promoter, could successfully induce heritable transcriptional gene silencing (TGS) of the green fluorescent protein (GFP) gene in the 35S-GFP transgenic N. benthamiana line 16c plants. Moreover, bisulfite sequencing results revealed higher methylated cytosine residues at CG, CHG and CHH sites of the 35S promoter sequence in TYLCCNV:35S-inoculated plants than in TYLCCNV-inoculated line 16c plants (control). Overall, these results demonstrated that the viral satellite DNA vector could be used as an effective VITGS vector to study DNA methylation in plant genomes.
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Affiliation(s)
- Zheng Ju
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Lei Wang
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Dongyan Cao
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Jinhua Zuo
- National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China.
| | - Hongliang Zhu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Daqi Fu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Yunbo Luo
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Benzhong Zhu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
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28
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Kikuchi Y, Hijikata N, Ohtomo R, Handa Y, Kawaguchi M, Saito K, Masuta C, Ezawa T. Aquaporin-mediated long-distance polyphosphate translocation directed towards the host in arbuscular mycorrhizal symbiosis: application of virus-induced gene silencing. THE NEW PHYTOLOGIST 2016; 211:1202-8. [PMID: 27136716 DOI: 10.1111/nph.14016] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 04/13/2016] [Indexed: 05/20/2023]
Abstract
Arbuscular mycorrhizal fungi translocate polyphosphate through hyphae over a long distance to deliver to the host. More than three decades ago, suppression of host transpiration was found to decelerate phosphate delivery of the fungal symbiont, leading us to hypothesize that transpiration provides a primary driving force for polyphosphate translocation, probably via creating hyphal water flow in which fungal aquaporin(s) may be involved. The impact of transpiration suppression on polyphosphate translocation through hyphae of Rhizophagus clarus was evaluated. An aquaporin gene expressed in intraradical mycelia was characterized and knocked down by virus-induced gene silencing to investigate the involvement of the gene in polyphosphate translocation. Rhizophagus clarus aquaporin 3 (RcAQP3) that was most highly expressed in intraradical mycelia encodes an aquaglyceroporin responsible for water transport across the plasma membrane. Knockdown of RcAQP3 as well as the suppression of host transpiration decelerated polyphosphate translocation in proportion to the levels of knockdown and suppression, respectively. These results provide the first insight into the mechanism underlying long-distance polyphosphate translocation in mycorrhizal associations at the molecular level, in which host transpiration and the fungal aquaporin play key roles. A hypothetical model of the translocation is proposed for further elucidation of the mechanism.
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Affiliation(s)
- Yusuke Kikuchi
- Graduate School of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan
| | - Nowaki Hijikata
- Graduate School of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan
| | - Ryo Ohtomo
- National Agriculture and Food Research Organization, Hokkaido Agricultural Research Center, Sapporo, 062-8555, Japan
| | - Yoshihiro Handa
- Division of Symbiotic Systems, National Institute for Basic Biology, Okazaki, 444-8585, Japan
| | - Masayoshi Kawaguchi
- Division of Symbiotic Systems, National Institute for Basic Biology, Okazaki, 444-8585, Japan
| | - Katsuharu Saito
- Faculty of Agriculture, Shinshu University, Minamiminowa, 399-4598, Japan
| | - Chikara Masuta
- Graduate School of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan
| | - Tatsuhiro Ezawa
- Graduate School of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan
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29
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Mermigka G, Verret F, Kalantidis K. RNA silencing movement in plants. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2016; 58:328-42. [PMID: 26297506 DOI: 10.1111/jipb.12423] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 08/20/2015] [Indexed: 05/21/2023]
Abstract
Multicellular organisms, like higher plants, need to coordinate their growth and development and to cope with environmental cues. To achieve this, various signal molecules are transported between neighboring cells and distant organs to control the fate of the recipient cells and organs. RNA silencing produces cell non-autonomous signal molecules that can move over short or long distances leading to the sequence specific silencing of a target gene in a well defined area of cells or throughout the entire plant, respectively. The nature of these signal molecules, the route of silencing spread, and the genes involved in their production, movement and reception are discussed in this review. Additionally, a short section on features of silencing spread in animal models is presented at the end of this review.
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Affiliation(s)
- Glykeria Mermigka
- Department of Biology, University of Crete, Heraklion, Crete, Greece
| | - Frédéric Verret
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, Crete, Greece
| | - Kriton Kalantidis
- Department of Biology, University of Crete, Heraklion, Crete, Greece
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, Crete, Greece
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30
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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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31
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Gohlke J, Mosher RA. Exploiting mobile RNA silencing for crop improvement. AMERICAN JOURNAL OF BOTANY 2015; 102:1399-400. [PMID: 26391704 DOI: 10.3732/ajb.1500173] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 06/18/2015] [Indexed: 05/21/2023]
Affiliation(s)
- Jochen Gohlke
- School of Plant Sciences, The University of Arizona, Tucson, Arizona 85721 USA
| | - Rebecca A Mosher
- School of Plant Sciences, The University of Arizona, Tucson, Arizona 85721 USA
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32
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Soler N, Fagoaga C, López C, Moreno P, Navarro L, Flores R, Peña L. Symptoms induced by transgenic expression of p23 from Citrus tristeza virus in phloem-associated cells of Mexican lime mimic virus infection without the aberrations accompanying constitutive expression. MOLECULAR PLANT PATHOLOGY 2015; 16:388-99. [PMID: 25171669 PMCID: PMC6638416 DOI: 10.1111/mpp.12188] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Citrus tristeza virus (CTV) is phloem restricted in natural citrus hosts. The 23-kDa protein (p23) encoded by the virus is an RNA silencing suppressor and a pathogenicity determinant. The expression of p23, or its N-terminal 157-amino-acid fragment comprising the zinc finger and flanking basic motifs, driven by the constitutive 35S promoter of cauliflower mosaic virus, induces CTV-like symptoms and other aberrations in transgenic citrus. To better define the role of p23 in CTV pathogenesis, we compared the phenotypes of Mexican lime transformed with p23-derived transgenes from the severe T36 and mild T317 CTV isolates under the control of the phloem-specific promoter from Commelina yellow mottle virus (CoYMV) or the 35S promoter. Expression of the constructs restricted to the phloem induced a phenotype resembling CTV-specific symptoms (vein clearing and necrosis, and stem pitting), but not the non-specific aberrations (such as mature leaf epinasty and yellow pinpoints, growth cessation and apical necrosis) observed when p23 was ectopically expressed. Furthermore, vein necrosis and stem pitting in Mexican lime appeared to be specifically associated with p23 from T36. Phloem-specific accumulation of the p23Δ158-209(T36) fragment was sufficient to induce the same anomalies, indicating that the region comprising the N-terminal 157 amino acids of p23 is responsible (at least in part) for the vein clearing, stem pitting and, possibly, vein corking in this host.
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Affiliation(s)
- Nuria Soler
- Centro de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias (IVIA), Apdo. Oficial, Moncada, Valencia, 46113, Spain
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33
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Hermann K, Klahre U, Venail J, Brandenburg A, Kuhlemeier C. The genetics of reproductive organ morphology in two Petunia species with contrasting pollination syndromes. PLANTA 2015; 241:1241-1254. [PMID: 25656052 DOI: 10.1007/s00425-015-2251-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 01/19/2015] [Indexed: 05/29/2023]
Abstract
Switches between pollination syndromes have happened frequently during angiosperm evolution. Using QTL mapping and reciprocal introgressions, we show that changes in reproductive organ morphology have a simple genetic basis. In animal-pollinated plants, flowers have evolved to optimize pollination efficiency by different pollinator guilds and hence reproductive success. The two Petunia species, P. axillaris and P. exserta, display pollination syndromes adapted to moth or hummingbird pollination. For the floral traits color and scent, genetic loci of large phenotypic effect have been well documented. However, such large-effect loci may be typical for shifts in simple biochemical traits, whereas the evolution of morphological traits may involve multiple mutations of small phenotypic effect. Here, we performed a quantitative trait locus (QTL) analysis of floral morphology, followed by an in-depth study of pistil and stamen morphology and the introgression of individual QTL into reciprocal parental backgrounds. Two QTLs, on chromosomes II and V, are sufficient to explain the interspecific difference in pistil and stamen length. Since most of the difference in organ length is caused by differences in cell number, genes underlying these QTLs are likely to be involved in cell cycle regulation. Interestingly, conservation of the locus on chromosome II in a different P. axillaris subspecies suggests that the evolution of organ elongation was initiated on chromosome II in adaptation to different pollinators. We recently showed that QTLs for pistil and stamen length on chromosome II are tightly linked to QTLs for petal color and volatile emission. Linkage of multiple traits will enable major phenotypic change within a few generations in hybridizing populations. Thus, the genomic architecture of pollination syndromes in Petunia allows for rapid responses to changing pollinator availability.
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Affiliation(s)
- Katrin Hermann
- Institute of Plant Sciences, Altenbergrain 21, 3013, Bern, Switzerland
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34
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Csorba T, Kontra L, Burgyán J. viral silencing suppressors: Tools forged to fine-tune host-pathogen coexistence. Virology 2015; 479-480:85-103. [DOI: 10.1016/j.virol.2015.02.028] [Citation(s) in RCA: 368] [Impact Index Per Article: 40.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 01/31/2015] [Accepted: 02/16/2015] [Indexed: 12/27/2022]
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35
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Chen W, Kong J, Qin C, Yu S, Tan J, Chen YR, Wu C, Wang H, Shi Y, Li C, Li B, Zhang P, Wang Y, Lai T, Yu Z, Zhang X, Shi N, Wang H, Osman T, Liu Y, Manning K, Jackson S, Rolin D, Zhong S, Seymour GB, Gallusci P, Hong Y. Requirement of CHROMOMETHYLASE3 for somatic inheritance of the spontaneous tomato epimutation Colourless non-ripening. Sci Rep 2015; 5:9192. [PMID: 25778911 PMCID: PMC4361866 DOI: 10.1038/srep09192] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 02/23/2015] [Indexed: 11/09/2022] Open
Abstract
Naturally-occurring epimutants are rare and have mainly been described in plants. However how these mutants maintain their epigenetic marks and how they are inherited remain unknown. Here we report that CHROMOMETHYLASE3 (SlCMT3) and other methyltransferases are required for maintenance of a spontaneous epimutation and its cognate Colourless non-ripening (Cnr) phenotype in tomato. We screened a series of DNA methylation-related genes that could rescue the hypermethylated Cnr mutant. Silencing of the developmentally-regulated SlCMT3 gene results in increased expression of LeSPL-CNR, the gene encodes the SBP-box transcription factor residing at the Cnr locus and triggers Cnr fruits to ripen normally. Expression of other key ripening-genes was also up-regulated. Targeted and whole-genome bisulfite sequencing showed that the induced ripening of Cnr fruits is associated with reduction of methylation at CHG sites in a 286-bp region of the LeSPL-CNR promoter, and a decrease of DNA methylation in differentially-methylated regions associated with the LeMADS-RIN binding sites. Our results indicate that there is likely a concerted effect of different methyltransferases at the Cnr locus and the plant-specific SlCMT3 is essential for sustaining Cnr epi-allele. Maintenance of DNA methylation dynamics is critical for the somatic stability of Cnr epimutation and for the inheritance of tomato non-ripening phenotype.
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Affiliation(s)
- Weiwei Chen
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Junhua Kong
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Cheng Qin
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Sheng Yu
- State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong
| | - Jinjuan Tan
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Yun-ru Chen
- State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong
| | - Chaoqun Wu
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Hui Wang
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Yan Shi
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Chunyang Li
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Bin Li
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Pengcheng Zhang
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Ying Wang
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Tongfei Lai
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Zhiming Yu
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Xian Zhang
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Nongnong Shi
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Huizhong Wang
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Toba Osman
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Yule Liu
- MOE Key Laboratory of Bioinformatics, Centre for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Kenneth Manning
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Stephen Jackson
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Dominique Rolin
- UMR Fruit Biology and Pathology, Bordeaux University, INRA, Villenave d′Ornon 33883, France
| | - Silin Zhong
- State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong
| | - Graham B. Seymour
- Plant and Crop Science Division, School of Biosciences, University of Nottingham, Loughborough, Leics LE12 5RD, UK
| | - Philippe Gallusci
- UMR Fruit Biology and Pathology, Bordeaux University, INRA, Villenave d′Ornon 33883, France
| | - Yiguo Hong
- Research Centre for Plant RNA Signalling, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
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36
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Kanazawa A, Kasai M. Induction of stable epigenetic gene silencing in plants using a virus vector. Methods Mol Biol 2015; 1287:129-37. [PMID: 25740361 DOI: 10.1007/978-1-4939-2453-0_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Gene silencing through transcriptional repression can be induced by double-stranded RNA targeted to a gene promoter, a process known as RNA-mediated transcriptional gene silencing (TGS). This phenomenon is associated with epigenetic changes involving cytosine methylation of the promoter. Plant virus vectors have been used to induce RNA-mediated TGS. Here, we describe methods relevant to the induction of epigenetic changes and RNA-mediated TGS in plants using a virus vector, which include inoculation of recombinant virus, detection of short interfering RNAs, bisulfite sequencing analysis, and nuclear run-on transcription assay.
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Affiliation(s)
- Akira Kanazawa
- Research Faculty of Agriculture, Hokkaido University, Kita 9, Nishi 9, Kita-ku, Sapporo, 060-8589, Japan,
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37
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Abstract
Understanding molecular mechanisms of transcriptional and posttranscriptional gene silencing pathways in plants over the past decades has led to development of tools and methods for silencing a target gene in various plant species. In this review chapter, both the recent understanding of molecular basis of gene silencing pathways and advances in various widely used gene silencing methods are compiled. We also discuss the salient features of the different methods like RNA interference (RNAi) and virus-induced gene silencing (VIGS) and highlight their advantages and disadvantages. Gene silencing technology is constantly progressing as reflected by rapidly emerging new methods. A succinct discussion on the recently developed methods like microRNA-mediated virus-induced gene silencing (MIR-VIGS) and microRNA-induced gene silencing (MIGS) is also provided. One major bottleneck in gene silencing approaches has been the associated off-target silencing. The other hurdle has been the lack of a universal approach that can be applied to all plants. For example, we face hurdles like incompatibility of VIGS vectors with the host and inability to use MIGS for plant species which are not easily transformable. However, the overwhelming research in this direction reflects the scope for overcoming the short comings of gene silencing technology.
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Affiliation(s)
- Prachi Pandey
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, #10531, New Delhi, 110067, India
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38
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Kon T, Yoshikawa N. Induction and maintenance of DNA methylation in plant promoter sequences by apple latent spherical virus-induced transcriptional gene silencing. Front Microbiol 2014; 5:595. [PMID: 25426109 PMCID: PMC4226233 DOI: 10.3389/fmicb.2014.00595] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 10/21/2014] [Indexed: 12/22/2022] Open
Abstract
Apple latent spherical virus (ALSV) is an efficient virus-induced gene silencing vector in functional genomics analyses of a broad range of plant species. Here, an Agrobacterium-mediated inoculation (agroinoculation) system was developed for the ALSV vector, and virus-induced transcriptional gene silencing (VITGS) is described in plants infected with the ALSV vector. The cDNAs of ALSV RNA1 and RNA2 were inserted between the cauliflower mosaic virus 35S promoter and the NOS-T sequences in a binary vector pCAMBIA1300 to produce pCALSR1 and pCALSR2-XSB or pCALSR2-XSB/MN. When these vector constructs were agroinoculated into Nicotiana benthamiana plants with a construct expressing a viral silencing suppressor, the infection efficiency of the vectors was 100%. A recombinant ALSV vector carrying part of the 35S promoter sequence induced transcriptional gene silencing of the green fluorescent protein gene in a line of N. benthamiana plants, resulting in the disappearance of green fluorescence of infected plants. Bisulfite sequencing showed that cytosine residues at CG and CHG sites of the 35S promoter sequence were highly methylated in the silenced generation zero plants infected with the ALSV carrying the promoter sequence as well as in progeny. The ALSV-mediated VITGS state was inherited by progeny for multiple generations. In addition, induction of VITGS of an endogenous gene (chalcone synthase-A) was demonstrated in petunia plants infected with an ALSV vector carrying the native promoter sequence. These results suggest that ALSV-based vectors can be applied to study DNA methylation in plant genomes, and provide a useful tool for plant breeding via epigenetic modification.
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Affiliation(s)
- Tatsuya Kon
- Plant Pathology Laboratory, Faculty of Agriculture, Iwate University Morioka, Japan
| | - Nobuyuki Yoshikawa
- Plant Pathology Laboratory, Faculty of Agriculture, Iwate University Morioka, Japan
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39
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Baulcombe DC, Dean C. Epigenetic regulation in plant responses to the environment. Cold Spring Harb Perspect Biol 2014; 6:a019471. [PMID: 25183832 DOI: 10.1101/cshperspect.a019471] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In this article, we review environmentally mediated epigenetic regulation in plants using two case histories. One of these, vernalization, mediates adaptation of plants to different environments and it exemplifies processes that are reset in each generation. The other, virus-induced silencing, involves transgenerationally inherited epigenetic modifications. Heritable epigenetic marks may result in heritable phenotypic variation, influencing fitness, and so be subject to natural selection. However, unlike genetic inheritance, the epigenetic modifications show instability and are influenced by the environment. These two case histories are then compared with other phenomena in plant biology that are likely to represent epigenetic regulation in response to the environment.
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Affiliation(s)
- David C Baulcombe
- Department of Plant Science, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| | - Caroline Dean
- Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, United Kingdom
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40
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Cherian S, Figueroa CR, Nair H. 'Movers and shakers' in the regulation of fruit ripening: a cross-dissection of climacteric versus non-climacteric fruit. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:4705-22. [PMID: 24994760 DOI: 10.1093/jxb/eru280] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Fruit ripening is a complex and highly coordinated developmental process involving the expression of many ripening-related genes under the control of a network of signalling pathways. The hormonal control of climacteric fruit ripening, especially ethylene perception and signalling transduction in tomato has been well characterized. Additionally, great strides have been made in understanding some of the major regulatory switches (transcription factors such as RIPENING-INHIBITOR and other transcriptional regulators such as COLOURLESS NON-RIPENING, TOMATO AGAMOUS-LIKE1 and ETHYLENE RESPONSE FACTORs), that are involved in tomato fruit ripening. In contrast, the regulatory network related to non-climacteric fruit ripening remains poorly understood. However, some of the most recent breakthrough research data have provided several lines of evidences for abscisic acid- and sucrose-mediated ripening of strawberry, a non-climacteric fruit model. In this review, we discuss the most recent research findings concerning the hormonal regulation of fleshy fruit ripening and their cross-talk and the future challenges taking tomato as a climacteric fruit model and strawberry as a non-climacteric fruit model. We also highlight the possible contribution of epigenetic changes including the role of plant microRNAs, which is opening new avenues and great possibilities in the fields of fruit-ripening research and postharvest biology.
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Affiliation(s)
- Sam Cherian
- Faculty of Integrative Sciences and Technology, Quest International University Perak, Jalan Raja Permaisuri Bainun, 30250 Ipoh, Perak Darul Ridzuan, Malaysia
| | - Carlos R Figueroa
- Faculty of Forest Sciences and Biotechnology Center, Universidad de Concepcion, Casilla 160-C, Concepcion, Chile
| | - Helen Nair
- Faculty of Integrative Sciences and Technology, Quest International University Perak, Jalan Raja Permaisuri Bainun, 30250 Ipoh, Perak Darul Ridzuan, Malaysia
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Cao D, Ju Z, Gao C, Mei X, Fu D, Zhu H, Luo Y, Zhu B. Genome-wide identification of cytosine-5 DNA methyltransferases and demethylases in Solanum lycopersicum. Gene 2014; 550:230-7. [PMID: 25149677 DOI: 10.1016/j.gene.2014.08.034] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 08/15/2014] [Accepted: 08/19/2014] [Indexed: 12/29/2022]
Abstract
Recent studies have reported that decreased level of DNA cytosine methylation in the global genome was closely related to the initiation of tomato (Solanum lycopersicum) fruit ripening. However, genome-scale analysis of cytosine-5 DNA methyltransferases (C5-MTases) and demethylases in tomato has not been engaged. In this study, 7 C5-MTases and 3 demethylases were identified in tomato genome, which probably contributed to DNA cytosine methylation level in tomato. The 7 C5-MTases were categorized into 4 subgroups, and the 3 demethylases were classified into 2 subgroups based on phylogenetic analyses. Comprehensive analysis of their structure and genomic localization was also performed in this paper. According to online RNA-seq data, 4 S. lycopersicum C5-MTase (SlC5-MTase) genes (SlMET, SlDRM1L1, SlDRM5, SlMET3L) were expressed higher than others, and one DNA demethylase gene (SlDML) was significantly changed during tomato fruit development and ripening. Furthermore, all these five gene expressions at breaker (BK) stage changed with 1-methylcyclopropene (1-MCP) treatment, indicating that they were regulated by ethylene directly or indirectly in tomato fruit. In addition, subcellular localization analysis indicated that SlDRM1L1 and SlDRM5 located in the nucleus might have responsibility for RNA-directed DNA methylation (RdDM). Collectively, this paper provided a framework for gene discovery and functional characterization of C5-MTases and DNA demethylases in other Solanaceae species.
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Affiliation(s)
- Dongyan Cao
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Zheng Ju
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Chao Gao
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Xiaohong Mei
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Daqi Fu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Hongliang Zhu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Yunbo Luo
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Benzhong Zhu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
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Ramesh SV, Ratnaparkhe MB, Kumawat G, Gupta GK, Husain SM. Plant miRNAome and antiviral resistance: a retrospective view and prospective challenges. Virus Genes 2014; 48:1-14. [PMID: 24445902 DOI: 10.1007/s11262-014-1038-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 01/12/2014] [Indexed: 12/20/2022]
Abstract
MicroRNAs (miRNAs) are small regulatory RNAs that play a defining role in post-transcriptional gene silencing of eukaryotes by either mRNA cleavage or translational inhibition. Plant miRNAs have been implicated in innumerable growth and developmental processes that extend beyond their ability to respond to biotic and abiotic stresses. Active in an organism's immune defence response, host miRNAs display a propensity to target viral genomes. During viral invasion, these virus-targeting miRNAs can be identified by their altered expression. All the while, pathogenic viruses, as a result of their long-term interaction with plants, have been evolving viral suppressors of RNA silencing (VSRs), as well as viral-encoded miRNAs as a counter-defence strategy. However, the gene silencing attribute of miRNAs has been ingeniously manipulated to down-regulate the expression of any gene of interest, including VSRs, in artificial miRNA (amiRNA)-based transgenics. Since we currently have a better understanding of the intricacies of miRNA-mediated gene regulation in plant-virus interactions, the majority of miRNAs manipulated to confer antiviral resistance to date are in plants. This review will share the insights gained from the studies of plant-virus combat and from the endeavour to manipulate miRNAs, including prospective challenges in the context of the evolutionary dynamics of the viral genome. Next generation sequencing technologies and bioinformatics analysis will further delineate the molecular details of host-virus interactions. The need for appropriate environmental risk assessment principles specific to amiRNA-based virus resistance is also discussed.
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Affiliation(s)
- Shunmugiah Veluchamy Ramesh
- Directorate of Soybean Research, Indian Council of Agricultural Research (ICAR), Khandwa Road, Indore, 452001, Madhya Pradesh, India,
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43
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Kondo K, Nakamura K. [Scientific review on novel genome editing techniques]. Food Hygiene and Safety Science (Shokuhin Eiseigaku Zasshi) 2014; 55:231-46. [PMID: 25743586 DOI: 10.3358/shokueishi.55.231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Pumplin N, Voinnet O. RNA silencing suppression by plant pathogens: defence, counter-defence and counter-counter-defence. Nat Rev Microbiol 2013; 11:745-60. [PMID: 24129510 DOI: 10.1038/nrmicro3120] [Citation(s) in RCA: 391] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
RNA silencing is a central regulator of gene expression in most eukaryotes and acts both at the transcriptional level through DNA methylation and at the post-transcriptional level through direct mRNA interference mediated by small RNAs. In plants and invertebrates, the same pathways also function directly in host defence against viruses by targeting viral RNA for degradation. Successful viruses have consequently evolved diverse mechanisms to avoid silencing, most notably through the expression of viral suppressors of RNA silencing. RNA silencing suppressors have also been recently identified in plant pathogenic bacteria and oomycetes, suggesting that disruption of host silencing is a general virulence strategy across several kingdoms of plant pathogens. There is also increasing evidence that plants have evolved specific defences against RNA-silencing suppression by pathogens, providing yet another illustration of the never-ending molecular arms race between plant pathogens and their hosts.
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Affiliation(s)
- Nathan Pumplin
- Swiss Federal Institute of Technology Zurich (ETH-Zurich), Department of Biology, Zurich, Switzerland
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Pflieger SP, Richard MMS, Blanchet S, Meziadi C, Geffroy VR. VIGS technology: an attractive tool for functional genomics studies in legumes. FUNCTIONAL PLANT BIOLOGY : FPB 2013; 40:1234-1248. [PMID: 32481191 DOI: 10.1071/fp13089] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 06/14/2013] [Indexed: 05/20/2023]
Abstract
Legume species are among the most important crops worldwide. In recent years, six legume genomes have been completely sequenced, and there is now an urgent need for reverse-genetics tools to validate genes affecting yield and product quality. As most legumes are recalcitrant to stable genetic transformation, virus-induced gene silencing (VIGS) appears to be a powerful alternative technology for determining the function of unknown genes. VIGS technology is based on the property of plant viruses to trigger a defence mechanism related to post-transcriptional gene silencing (PTGS). Infection by a recombinant virus carrying a fragment of a plant target gene will induce homology-dependent silencing of the endogenous target gene. Several VIGS systems have been developed for legume species since 2004, including those based on Bean pod mottle virus, Pea early browning virus, and Apple latent spherical virus, and used in reverse-genetics studies of a wide variety of plant biological processes. In this work, we give an overview of the VIGS systems available for legumes, and present their successful applications in functional genomics studies. We also discuss the limitations of these VIGS systems and the future challenges to be faced in order to use VIGS to its full potential in legume species.
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Affiliation(s)
- St Phanie Pflieger
- Institut de Biologie des Plantes, UMR8618, CNRS Université Paris-Sud, Saclay Plant Sciences, Rue Noetzlin, 91405 Orsay, France
| | - Manon M S Richard
- Institut de Biologie des Plantes, UMR8618, CNRS Université Paris-Sud, Saclay Plant Sciences, Rue Noetzlin, 91405 Orsay, France
| | - Sophie Blanchet
- Institut de Biologie des Plantes, UMR8618, CNRS Université Paris-Sud, Saclay Plant Sciences, Rue Noetzlin, 91405 Orsay, France
| | - Chouaib Meziadi
- Institut de Biologie des Plantes, UMR8618, CNRS Université Paris-Sud, Saclay Plant Sciences, Rue Noetzlin, 91405 Orsay, France
| | - Val Rie Geffroy
- Institut de Biologie des Plantes, UMR8618, CNRS Université Paris-Sud, Saclay Plant Sciences, Rue Noetzlin, 91405 Orsay, France
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Sahu PP, Pandey G, Sharma N, Puranik S, Muthamilarasan M, Prasad M. Epigenetic mechanisms of plant stress responses and adaptation. PLANT CELL REPORTS 2013; 32:1151-9. [PMID: 23719757 DOI: 10.1007/s00299-013-1462-x] [Citation(s) in RCA: 134] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 05/20/2013] [Accepted: 05/20/2013] [Indexed: 05/20/2023]
Abstract
Epigenetics has become one of the hottest topics of research in plant functional genomics since it appears promising in deciphering and imparting stress-adaptive potential in crops and other plant species. Recently, numerous studies have provided new insights into the epigenetic control of stress adaptation. Epigenetic control of stress-induced phenotypic response of plants involves gene regulation. Growing evidence suggest that methylation of DNA in response to stress leads to the variation in phenotype. Transposon mobility, siRNA-mediated methylation and host methyltransferase activation have been implicated in this process. This review presents the current status of epigenetics of plant stress responses with a view to use this knowledge towards engineering plants for stress tolerance.
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Affiliation(s)
- Pranav Pankaj Sahu
- National Institute of Plant Genome Research (NIPGR), Aruna Asaf Ali Marg, New Delhi, 110 067, India
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Incarbone M, Dunoyer P. RNA silencing and its suppression: novel insights from in planta analyses. TRENDS IN PLANT SCIENCE 2013; 18:382-92. [PMID: 23684690 DOI: 10.1016/j.tplants.2013.04.001] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 03/25/2013] [Accepted: 04/04/2013] [Indexed: 05/19/2023]
Abstract
Plants employ multiple layers of innate immunity to fight pathogens. For both RNA and DNA viruses, RNA silencing plays a critical role in plant resistance. To escape this antiviral silencing-based immune response, viruses have evolved various counterdefense strategies, the most widespread being production of viral suppressors of RNA silencing (VSRs) that target various stages of the silencing mechanisms. Recent findings from in planta analyses have provided new insights into the mode of action of VSRs and revealed that plants react to the perturbation of the silencing pathways brought by viral infection by deploying a battery of counter-counterdefense measures. As well as discussing which experimental approaches have been most effective in delivering clear and unambiguous results, this review provides a detailed account of the surprising variety of offensive and defensive strategies set forth by both viruses and hosts in their struggle for survival.
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Affiliation(s)
- Marco Incarbone
- IBMP-CNRS, 12 rue du General Zimmer, 67084 Strasbourg Cedex, France
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48
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Otagaki S, Kasai M, Masuta C, Kanazawa A. Enhancement of RNA-directed DNA methylation of a transgene by simultaneously downregulating a ROS1 ortholog using a virus vector in Nicotiana benthamiana. Front Genet 2013; 4:44. [PMID: 23565118 PMCID: PMC3613619 DOI: 10.3389/fgene.2013.00044] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 03/12/2013] [Indexed: 12/11/2022] Open
Abstract
Cytosine methylation can be induced by double-stranded RNAs through the RNA-directed DNA methylation (RdDM) pathway. A DNA glycosylase REPRESSOR OF SILENCING 1 (ROS1) participates in DNA demethylation in Arabidopsis and may possibly counteract RdDM. Here, we isolated an ortholog of ROS1 (NbROS1) from Nicotiana benthamiana and examined the antagonistic activity of NbROS1 against virus-induced RdDM by simultaneously inducing RdDM and NbROS1 knockdown using a vector based on Cucumber mosaic virus. Plants were inoculated with a virus that contained a portion of the Cauliflower mosaic virus 35S promoter, which induced RdDM of the promoter integrated in the plant genome and transcriptional silencing of the green fluorescent protein gene driven by the promoter. Plants were also inoculated with a virus that contained a portion of NbROS1, which induced downregulation of NbROS1. Simultaneous induction of RdDM and NbROS1 knockdown resulted in an increase in the level of cytosine methylation of the target promoter. These results provide evidence for the presence of antagonistic activity of NbROS1 against virus-induced RdDM and suggest that the simultaneous induction of promoter-targeting RdDM and NbROS1 knockdown by a virus vector is useful as a tool to enhance targeted DNA methylation.
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Affiliation(s)
- Shungo Otagaki
- Research Faculty of Agriculture, Hokkaido University Sapporo, Japan
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Seymour GB, Chapman NH, Chew BL, Rose JKC. Regulation of ripening and opportunities for control in tomato and other fruits. PLANT BIOTECHNOLOGY JOURNAL 2013; 11:269-78. [PMID: 22958755 DOI: 10.1111/j.1467-7652.2012.00738.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 07/23/2012] [Accepted: 07/25/2012] [Indexed: 05/21/2023]
Abstract
Fruits are an important part of a healthy diet. They provide essential vitamins and minerals, and their consumption is associated with a reduced risk of heart disease and certain cancers. These important plant products can, however, be expensive to purchase, may be of disappointing quality and often have a short shelf life. A major challenge for crop improvement in fleshy fruit species is the enhancement of their health-promoting attributes while improving quality and reducing postharvest waste. To achieve these aims, a sound mechanistic understanding of the processes involved in fruit development and ripening is needed. In recent years, substantial insights have been made into the mechanistic basis of ethylene biosynthesis, perception and signalling and the identity of master regulators of ripening that operate upstream of, or in concert with a regulatory pathway mediated by this plant hormone. The role of other plant hormones in the ripening process has, however, remained elusive, and the links between regulators and downstream processes are still poorly understood. In this review, we focus on tomato as a model for fleshy fruit and provide an overview of the molecular circuits known to be involved in ripening, especially those controlling pigment accumulation and texture changes. We then discuss how this information can be used to understand ripening in other fleshy fruit-bearing species. Recent developments in comparative genomics and systems biology approaches are discussed. The potential role of epigenetic changes in generating useful variation is highlighted along with opportunities for enhancing the level of metabolites that have a beneficial effect on human health.
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Affiliation(s)
- Graham B Seymour
- Plant and Crops Sciences Division, University of Nottingham, Loughborough, Leics, UK
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50
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Ruiz-Ruiz S, Soler N, Sánchez-Navarro J, Fagoaga C, López C, Navarro L, Moreno P, Peña L, Flores R. Citrus tristeza virus p23: determinants for nucleolar localization and their influence on suppression of RNA silencing and pathogenesis. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:306-18. [PMID: 23387469 DOI: 10.1094/mpmi-08-12-0201-r] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Citrus tristeza virus (CTV) encodes a singular protein (p23, 209 amino acids) with multiple functions, including RNA silencing suppression (RSS). Confocal laser-scanning microscopy of green fluorescent protein (GFP)-p23 agroexpressed in Nicotiana benthamiana revealed its accumulation in the nucleolus, Cajal bodies, and plasmodesmata. To dissect the nucleolar localization signal (NoLS) typically associated with basic motifs, seven truncated and 10 point-mutated versions of p23 were assayed. Deletion mutants showed that regions 50 to 86 and 100 to 157 (excluding fragment 106 to 114), both with basic motifs and the first with a zinc-finger, contain the (bipartite) NoLS. Alanine substitutions delimited this signal to three cysteines of the Zn-finger and some basic amino acids. RSS activity of p23 in N. benthamiana was abolished by essentially all mutants, indicating that it involves most p23 regions. The necrotic-inducing ability of p23 when launched in N. benthamiana from Potato virus X was only retained by deletion mutant 158-209 and one substitution mutant, showing that the Zn-finger and flanking basic motifs form part of the pathogenic determinant. Ectopic expression of p23 and some deletion mutants in transgenic Mexican lime demarcated a similar determinant, suggesting that p23 affects related pathways in citrus and N. benthamiana. Both RSS activity and pathogenicity of p23 appear related to its nucleolar localization.
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Affiliation(s)
- Susana Ruiz-Ruiz
- Consejo Superior de Investigaciones Cientificas-Universidad Politecnica de Valencia, Spain
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