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Khan ZA, Gupta K, Dasgupta I. Transient expression analysis of promoters of okra enation leaf curl virus in Nicotiana benthamiana, cotton and okra plants. Virus Genes 2024; 60:412-422. [PMID: 38727968 DOI: 10.1007/s11262-024-02074-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Accepted: 04/22/2024] [Indexed: 07/13/2024]
Abstract
Viral promoters can be used to drive heterologous gene expression in transgenic plants. As part of our quest to look for new promoters, we have explored, for the first time, the promoters of okra enation leaf curl virus (OELCuV), a begomovirus infecting okra (Abelmoschus esculentus). The Rep and CP promoters of OELCuV fused with the gfp reporter gene, were expressed transiently in the natural host okra and the laboratory host cotton and Nicotiana benthamiana. The expression levels of the promoters were quantified through confocal laser scanning microscopy and GFP assay in N. benthamiana and okra. The results indicated that the Rep promoter was more active than the CP promoter, whose activity was similar to that of CaMV 35S promoter. Additionally, the Rep and CP promoters showed increase of expression, probably due to transactivation, when assayed following inoculation of OELCuV and betasatellite DNAs in cotton plants. A moderate increase in promoter activity in N. benthamiana was also seen, when assayed following the inoculation of the heterologous begomovirus Sri Lankan cassava mosaic virus.
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Affiliation(s)
- Zainul A Khan
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, 110021, India
| | - Kanika Gupta
- 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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Kamal H, Zafar MM, Razzaq A, Parvaiz A, Ercisli S, Qiao F, Jiang X. Functional role of geminivirus encoded proteins in the host: Past and present. Biotechnol J 2024; 19:e2300736. [PMID: 38900041 DOI: 10.1002/biot.202300736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 03/19/2024] [Accepted: 04/16/2024] [Indexed: 06/21/2024]
Abstract
During plant-pathogen interaction, plant exhibits a strong defense system utilizing diverse groups of proteins to suppress the infection and subsequent establishment of the pathogen. However, in response, pathogens trigger an anti-silencing mechanism to overcome the host defense machinery. Among plant viruses, geminiviruses are the second largest virus family with a worldwide distribution and continue to be production constraints to food, feed, and fiber crops. These viruses are spread by a diverse group of insects, predominantly by whiteflies, and are characterized by a single-stranded DNA (ssDNA) genome coding for four to eight proteins that facilitate viral infection. The most effective means to managing these viruses is through an integrated disease management strategy that includes virus-resistant cultivars, vector management, and cultural practices. Dynamic changes in this virus family enable the species to manipulate their genome organization to respond to external changes in the environment. Therefore, the evolutionary nature of geminiviruses leads to new and novel approaches for developing virus-resistant cultivars and it is essential to study molecular ecology and evolution of geminiviruses. This review summarizes the multifunctionality of each geminivirus-encoded protein. These protein-based interactions trigger the abrupt changes in the host methyl cycle and signaling pathways that turn over protein normal production and impair the plant antiviral defense system. Studying these geminivirus interactions localized at cytoplasm-nucleus could reveal a more clear picture of host-pathogen relation. Data collected from this antagonistic relationship among geminivirus, vector, and its host, will provide extensive knowledge on their virulence mode and diversity with climate change.
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Affiliation(s)
- Hira Kamal
- Department of Plant Pathology, Washington State University, Pullman, Washington, USA
| | - Muhammad Mubashar Zafar
- Sanya Institute of Breeding and Multiplication, School of Tropical Agriculture and Forestry, Hainan University, Sanya, China
| | - Abdul Razzaq
- Institute of Molecular Biology and Biotechnology, The University of Lahore, Lahore, Pakistan
| | - Aqsa Parvaiz
- Department of Biochemistry and Biotechnology, The Women University Multan, Multan, Pakistan
| | - Sezai Ercisli
- Department of Horticulture, Faculty of Agriculture, Ataturk University, Erzurum, Turkey
| | - Fei Qiao
- Sanya Institute of Breeding and Multiplication, School of Tropical Agriculture and Forestry, Hainan University, Sanya, China
| | - Xuefei Jiang
- Sanya Institute of Breeding and Multiplication, School of Tropical Agriculture and Forestry, Hainan University, Sanya, China
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Jammes M, Golyaev V, Fuentes A, Laboureau N, Urbino C, Plissonneau C, Peterschmitt M, Pooggin MM. Transcriptome and small RNAome profiling uncovers how a recombinant begomovirus evades RDRγ-mediated silencing of viral genes and outcompetes its parental virus in mixed infection. PLoS Pathog 2024; 20:e1011941. [PMID: 38215155 PMCID: PMC10810479 DOI: 10.1371/journal.ppat.1011941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 01/25/2024] [Accepted: 01/03/2024] [Indexed: 01/14/2024] Open
Abstract
Tomato yellow leaf curl virus (TYLCV, genus Begomovirus, family Geminiviridae) causes severe disease of cultivated tomatoes. Geminiviruses replicate circular single-stranded genomic DNA via rolling-circle and recombination-dependent mechanisms, frequently generating recombinants in mixed infections. Circular double-stranded intermediates of replication also serve as templates for Pol II bidirectional transcription. IS76, a recombinant derivative of TYLCV with a short sequence in the bidirectional promoter/origin-of-replication region acquired from a related begomovirus, outcompetes TYLCV in mixed infection and breaks disease resistance in tomato Ty-1 cultivars. Ty-1 encodes a γ-clade RNA-dependent RNA polymerase (RDRγ) implicated in Dicer-like (DCL)-mediated biogenesis of small interfering (si)RNAs directing gene silencing. Here, we profiled transcriptome and small RNAome of Ty-1 resistant and control susceptible plants infected with TYLCV, IS76 or their combination at early and late infection stages. We found that RDRγ boosts production rates of 21, 22 and 24 nt siRNAs from entire genomes of both viruses and modulates DCL activities in favour of 22 and 24 nt siRNAs. Compared to parental TYLCV, IS76 undergoes faster transition to the infection stage favouring rightward transcription of silencing suppressor and coat protein genes, thereby evading RDRγ activity and facilitating its DNA accumulation in both single and mixed infections. In coinfected Ty-1 plants, IS76 efficiently competes for host replication and transcription machineries, thereby impairing TYLCV replication and transcription and forcing its elimination associated with further increased siRNA production. RDRγ is constitutively overexpressed in Ty-1 plants, which correlates with begomovirus resistance, while siRNA-generating DCLs (DCL2b/d, DCL3, DCL4) and genes implicated in siRNA amplification (α-clade RDR1) and function (Argonaute2) are upregulated to similar levels in TYLCV- and IS76-infected susceptible plants. Collectively, IS76 recombination facilitates replication and promotes expression of silencing suppressor and coat proteins, which allows the recombinant virus to evade the negative impact of RDRγ-boosted production of viral siRNAs directing transcriptional and posttranscriptional silencing.
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Affiliation(s)
- Margaux Jammes
- PHIM Plant Health Institute, University Montpellier, CIRAD, INRAE, IRD, Institute Agro, Montpellier, France
| | - Victor Golyaev
- PHIM Plant Health Institute, University Montpellier, CIRAD, INRAE, IRD, Institute Agro, Montpellier, France
| | | | - Nathalie Laboureau
- PHIM Plant Health Institute, University Montpellier, CIRAD, INRAE, IRD, Institute Agro, Montpellier, France
| | - Cica Urbino
- PHIM Plant Health Institute, University Montpellier, CIRAD, INRAE, IRD, Institute Agro, Montpellier, France
| | | | - Michel Peterschmitt
- PHIM Plant Health Institute, University Montpellier, CIRAD, INRAE, IRD, Institute Agro, Montpellier, France
| | - Mikhail M. Pooggin
- PHIM Plant Health Institute, University Montpellier, CIRAD, INRAE, IRD, Institute Agro, Montpellier, France
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Pfrieme AK, Will T, Pillen K, Stahl A. The Past, Present, and Future of Wheat Dwarf Virus Management-A Review. PLANTS (BASEL, SWITZERLAND) 2023; 12:3633. [PMID: 37896096 PMCID: PMC10609771 DOI: 10.3390/plants12203633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 09/29/2023] [Accepted: 10/04/2023] [Indexed: 10/29/2023]
Abstract
Wheat dwarf disease (WDD) is an important disease of monocotyledonous species, including economically important cereals. The causative pathogen, wheat dwarf virus (WDV), is persistently transmitted mainly by the leafhopper Psammotettix alienus and can lead to high yield losses. Due to climate change, the periods of vector activity increased, and the vectors have spread to new habitats, leading to an increased importance of WDV in large parts of Europe. In the light of integrated pest management, cultivation practices and the use of resistant/tolerant host plants are currently the only effective methods to control WDV. However, knowledge of the pathosystem and epidemiology of WDD is limited, and the few known sources of genetic tolerance indicate that further research is needed. Considering the economic importance of WDD and its likely increasing relevance in the coming decades, this study provides a comprehensive compilation of knowledge on the most important aspects with information on the causal virus, its vector, symptoms, host range, and control strategies. In addition, the current status of genetic and breeding efforts to control and manage this disease in wheat will be discussed, as this is crucial to effectively manage the disease under changing environmental conditions and minimize impending yield losses.
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Affiliation(s)
- Anne-Kathrin Pfrieme
- Institute for Resistance Research and Stress Tolerance, Julius Kühn Institute (JKI)—Federal Research Centre for Cultivated Plants, 06484 Quedlinburg, Germany; (T.W.); (A.S.)
| | - Torsten Will
- Institute for Resistance Research and Stress Tolerance, Julius Kühn Institute (JKI)—Federal Research Centre for Cultivated Plants, 06484 Quedlinburg, Germany; (T.W.); (A.S.)
| | - Klaus Pillen
- Institute of Agricultural and Nutritional Science, Plant Breeding, Martin-Luther-University Halle-Wittenberg, 06108 Halle (Saale), Germany;
| | - Andreas Stahl
- Institute for Resistance Research and Stress Tolerance, Julius Kühn Institute (JKI)—Federal Research Centre for Cultivated Plants, 06484 Quedlinburg, Germany; (T.W.); (A.S.)
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Lin W, Qiu P, Xu Y, Chen L, Wu Z, Zhang J, Du Z. Transcription start site mapping of geminiviruses using the in vitro cap-snatching of a tenuivirus. J Virol Methods 2023; 319:114757. [PMID: 37257758 DOI: 10.1016/j.jviromet.2023.114757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 05/26/2023] [Accepted: 05/27/2023] [Indexed: 06/02/2023]
Abstract
Geminiviruses are a family of single-stranded DNA viruses that cause significant yield losses in crop production worldwide. Transcription start site (TSS) mapping is crucial in understanding the gene expression mechanisms of geminiviruses. However, this often requires costly and laborious experiments. Rice stripe virus (RSV) has a mechanism called cap-snatching, whereby it cleaves cellular mRNAs and uses the 5' cleavage product, a capped-RNA leader (CRL), as primers for transcription. Our previous work demonstrated that RSV snatches CRLs from geminiviral mRNAs in co-infected plants, providing a convenient and powerful approach to map the TSSs of geminiviruses. However, co-infections are not always feasible for all geminiviruses. In this study, we evaluated the use of in vitro cap-snatching of RSV for the same purpose, using tomato yellow leaf curl virus (TYLCV) as an example. We incubated RNA extracted from TYLCV-infected plants with purified RSV ribonucleoproteins in a reaction mixture that supports in vitro cap-snatching of RSV. The RSV mRNAs produced in the reaction were deep sequenced. The CRLs snatched by RSV allowed us to locate 28 TSSs in TYLCV. These results provide support for using RSV's in vitro cap-snatching to map geminiviral TSSs.
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Affiliation(s)
- Wenzhong Lin
- Institute of Plant Virology, Fujian Agricultural and Forestry University, Fuzhou 350002, China
| | - Ping Qiu
- Institute of Plant Virology, Fujian Agricultural and Forestry University, Fuzhou 350002, China
| | - Yixing Xu
- Institute of Plant Virology, Fujian Agricultural and Forestry University, Fuzhou 350002, China
| | - Lihong Chen
- Institute of Plant Virology, Fujian Agricultural and Forestry University, Fuzhou 350002, China
| | - Zujian Wu
- Institute of Plant Virology, Fujian Agricultural and Forestry University, Fuzhou 350002, China; State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Jie Zhang
- Institute of Plant Virology, Fujian Agricultural and Forestry University, Fuzhou 350002, China; State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China.
| | - Zhenguo Du
- Institute of Plant Virology, Fujian Agricultural and Forestry University, Fuzhou 350002, China; State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China.
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6
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Zwolinski AM, Brigden A, Rey MEC. Differences in the 3' intergenic region and the V2 protein of two sequence variants of tomato curly stunt virus play an important role in disease pathology in Nicotiana benthamiana. PLoS One 2023; 18:e0286149. [PMID: 37220127 PMCID: PMC10205009 DOI: 10.1371/journal.pone.0286149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 05/10/2023] [Indexed: 05/25/2023] Open
Abstract
Tomato production in South Africa is threatened by the emergence of tomato curly stunt virus (ToCSV), a monopartite Begomovirus transmitted by the whitefly vector Bemisia tabaci (Genn.). We investigated the role of sequence differences present in the 3' intergenic region (IR) and the V2 coding region on the differing infectivity of ToCSV sequence variant isolates V30 and V22 in the model host Nicotiana benthamiana. Using virus mutant chimeras, we determined that the development of the upward leaf roll symptom phenotype is mediated by sequence differences present in the 3' IR containing the TATA-associated composite element. Sequence differences present in the V2 coding region are responsible for modulating disease severity and symptom recovery in V22-infected plants. Serine substitution of V22 V2 Val27 resulted in a significant increase in disease severity with reduced recovery, the first study to demonstrate the importance of this V2 residue in disease development. Two putative ORFs, C5 and C6, were identified using in silico analysis and detection of an RNA transcript spanning their coding region suggests that these ORFs may be transcribed during infection. Additional virus-derived RNA transcripts spanning multiple ORFs and crossing the boundaries of recognised polycistronic transcripts, as well as the origin of replication within the IR, were detected in ToCSV-infected plants providing evidence of bidirectional readthrough transcription. From our results, we conclude that the diverse responses of the model host to ToCSV infection is influenced by select sequence differences and our findings provide several avenues for further investigation into the mechanisms behind these responses to infection.
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Affiliation(s)
- Alexander M. Zwolinski
- School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, South Africa
| | - Alison Brigden
- School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, South Africa
| | - Marie E. C. Rey
- School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, South Africa
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Gupta N, Reddy K, Gnanasekaran P, Zhai Y, Chakraborty S, Pappu HR. Functional characterization of a new ORF βV1 encoded by radish leaf curl betasatellite. FRONTIERS IN PLANT SCIENCE 2022; 13:972386. [PMID: 36212370 PMCID: PMC9546537 DOI: 10.3389/fpls.2022.972386] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Accepted: 08/10/2022] [Indexed: 05/26/2023]
Abstract
Whitefly-transmitted begomoviruses infect and damage a wide range of food, feed, and fiber crops worldwide. Some of these viruses are associated with betasatellite molecules that are known to enhance viral pathogenesis. In this study, we investigated the function of a novel βV1 protein encoded by radish leaf curl betasatellite (RaLCB) by overexpressing the protein using potato virus X (PVX)-based virus vector in Nicotiana benthamiana. βV1 protein induced lesions on leaves, suggestive of hypersensitive response (HR), indicating cell death. The HR reaction induced by βV1 protein was accompanied by an increased accumulation of reactive oxygen species (ROS), free radicals, and HR-related transcripts. Subcellular localization through confocal microscopy revealed that βV1 protein localizes to the cellular periphery. βV1 was also found to interact with replication enhancer protein (AC3) of helper virus in the nucleus. The current findings suggest that βV1 functions as a protein elicitor and a pathogenicity determinant.
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Affiliation(s)
- Neha Gupta
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
- Department of Plant Pathology, Washington State University, Pullman, WA, United States
| | - Kishorekumar Reddy
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Prabu Gnanasekaran
- Department of Plant Pathology, Washington State University, Pullman, WA, United States
| | - Ying Zhai
- Department of Plant Pathology, Washington State University, Pullman, WA, United States
| | - Supriya Chakraborty
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Hanu R. Pappu
- Department of Plant Pathology, Washington State University, Pullman, WA, United States
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Chiu CW, Li YR, Lin CY, Yeh HH, Liu MJ. Translation initiation landscape profiling reveals hidden open-reading frames required for the pathogenesis of tomato yellow leaf curl Thailand virus. THE PLANT CELL 2022; 34:1804-1821. [PMID: 35080617 PMCID: PMC9048955 DOI: 10.1093/plcell/koac019] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 01/06/2022] [Indexed: 05/12/2023]
Abstract
Plant viruses with densely packed genomes employ noncanonical translational strategies to increase the coding capacity for viral function. However, the diverse translational strategies used make it challenging to define the full set of viral genes. Here, using tomato yellow leaf curl Thailand virus (TYLCTHV, genus Begomovirus) as a model system, we identified genes beyond the annotated gene sets by experimentally profiling in vivo translation initiation sites (TISs). We found that unanticipated AUG TISs were prevalent and determined that their usage involves alternative transcriptional and/or translational start sites and is associated with flanking mRNA sequences. Specifically, two downstream in-frame TISs were identified in the viral gene AV2. These TISs were conserved in the begomovirus lineage and led to the translation of different protein isoforms localized to cytoplasmic puncta and at the cell periphery, respectively. In addition, we found translational evidence of an unexplored gene, BV2. BV2 is conserved among TYLCTHV isolates and localizes to the endoplasmic reticulum and plasmodesmata. Mutations of AV2 isoforms and BV2 significantly attenuated disease symptoms in tomato (Solanum lycopersicum). In conclusion, our study pinpointing in vivo TISs untangles the coding complexity of a plant viral genome and, more importantly, illustrates the biological significance of the hidden open-reading frames encoding viral factors for pathogenicity.
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Affiliation(s)
- Ching-Wen Chiu
- Biotechnology Center in Southern Taiwan, Academia Sinica, Tainan 711, Taiwan
| | - Ya-Ru Li
- Biotechnology Center in Southern Taiwan, Academia Sinica, Tainan 711, Taiwan
| | - Cheng-Yuan Lin
- Biotechnology Center in Southern Taiwan, Academia Sinica, Tainan 711, Taiwan
| | - Hsin-Hung Yeh
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan
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Devendran R, Namgial T, Reddy KK, Kumar M, Zarreen F, Chakraborty S. Insights into the multifunctional roles of geminivirus-encoded proteins in pathogenesis. Arch Virol 2022; 167:307-326. [PMID: 35079902 DOI: 10.1007/s00705-021-05338-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 10/23/2021] [Indexed: 12/18/2022]
Abstract
Geminiviruses are a major threat to agriculture in tropical and subtropical regions of the world. Geminiviruses have small genome with limited coding capacity. Despite this limitation, these viruses have mastered hijacking the host cellular metabolism for their survival. To compensate for the small size of their genome, geminiviruses encode multifunctional proteins. In addition, geminiviruses associate themselves with satellite DNA molecules which also encode proteins that support the virus in establishing successful infection. Geminiviral proteins recruit multiple host factors, suppress the host defense, and manipulate host metabolism to establish infection. We have updated the knowledge accumulated about the proteins of geminiviruses and their satellites in the context of pathogenesis in a single review. We also discuss their interactions with host factors to provide a mechanistic understanding of the infection process.
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Affiliation(s)
- Ragunathan Devendran
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Tsewang Namgial
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Kishore Kumar Reddy
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Manish Kumar
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Fauzia Zarreen
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Supriya Chakraborty
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
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Zhang S, Sun R, Perdoncini Carvalho C, Han J, Zheng L, Qu F. Replication-Dependent Biogenesis of Turnip Crinkle Virus Long Noncoding RNAs. J Virol 2021; 95:e0016921. [PMID: 34160262 PMCID: PMC8387050 DOI: 10.1128/jvi.00169-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 06/14/2021] [Indexed: 12/24/2022] Open
Abstract
Long noncoding RNAs (lncRNAs) of virus origin accumulate in cells infected by many positive-strand (+) RNA viruses to bolster viral infectivity. Their biogenesis mostly utilizes exoribonucleases of host cells that degrade viral genomic or subgenomic RNAs in the 5'-to-3' direction until being stalled by well-defined RNA structures. Here, we report a viral lncRNA that is produced by a novel replication-dependent mechanism. This lncRNA corresponds to the last 283 nucleotides of the turnip crinkle virus (TCV) genome and hence is designated tiny TCV subgenomic RNA (ttsgR). ttsgR accumulated to high levels in TCV-infected Nicotiana benthamiana cells when the TCV-encoded RNA-dependent RNA polymerase (RdRp), also known as p88, was overexpressed. Both (+) and (-) strand forms of ttsgR were produced in a manner dependent on the RdRp functionality. Strikingly, templates as short as ttsgR itself were sufficient to program ttsgR amplification, as long as the TCV-encoded replication proteins p28 and p88 were provided in trans. Consistent with its replicational origin, ttsgR accumulation required a 5' terminal carmovirus consensus sequence (CCS), a sequence motif shared by genomic and subgenomic RNAs of many viruses phylogenetically related to TCV. More importantly, introducing a new CCS motif elsewhere in the TCV genome was alone sufficient to cause the emergence of another lncRNA. Finally, abolishing ttsgR by mutating its 5' CCS gave rise to a TCV mutant that failed to compete with wild-type TCV in Arabidopsis. Collectively, our results unveil a replication-dependent mechanism for the biogenesis of viral lncRNAs, thus suggesting that multiple mechanisms, individually or in combination, may be responsible for viral lncRNA production. IMPORTANCE Many positive-strand (+) RNA viruses produce long noncoding RNAs (lncRNAs) during the process of cellular infections and mobilize these lncRNAs to counteract antiviral defenses, as well as coordinate the translation of viral proteins. Most viral lncRNAs arise from 5'-to-3' degradation of longer viral RNAs being stalled at stable secondary structures. Here, we report a viral lncRNA that is produced by the replication machinery of turnip crinkle virus (TCV). This lncRNA, designated ttsgR, shares the terminal characteristics with TCV genomic and subgenomic RNAs and overaccumulates in the presence of moderately overexpressed TCV RNA-dependent RNA polymerase (RdRp). Furthermore, templates that are of similar sizes as ttsgR are readily replicated by TCV replication proteins (p28 and RdRp) provided from nonviral sources. In summary, this study establishes an approach for uncovering low abundance viral lncRNAs, and characterizes a replicating TCV lncRNA. Similar investigations on human-pathogenic (+) RNA viruses could yield novel therapeutic targets.
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Affiliation(s)
- Shaoyan Zhang
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
| | - Rong Sun
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
| | - Camila Perdoncini Carvalho
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
| | - Junping Han
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
| | - Limin Zheng
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
| | - Feng Qu
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
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The Baltimore Classification of Viruses 50 Years Later: How Does It Stand in the Light of Virus Evolution? Microbiol Mol Biol Rev 2021; 85:e0005321. [PMID: 34259570 DOI: 10.1128/mmbr.00053-21] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Fifty years ago, David Baltimore published a brief conceptual paper delineating the classification of viruses by the routes of genome expression. The six "Baltimore classes" of viruses, with a subsequently added 7th class, became the conceptual framework for the development of virology during the next five decades. During this time, it became clear that the Baltimore classes, with relatively minor additions, indeed cover the diversity of virus genome expression schemes that also define the replication cycles. Here, we examine the status of the Baltimore classes 50 years after their advent and explore their links with the global ecology and biology of the respective viruses. We discuss an extension of the Baltimore scheme and why many logically admissible expression-replication schemes do not appear to be realized in nature. Recent phylogenomic analyses allow tracing the complex connections between the Baltimore classes and the monophyletic realms of viruses. The five classes of RNA viruses and reverse-transcribing viruses share an origin, whereas both the single-stranded DNA viruses and double-stranded DNA (dsDNA) viruses evolved on multiple independent occasions. Most of the Baltimore classes of viruses probably emerged during the earliest era of life evolution, at the stage of the primordial pool of diverse replicators, and before the advent of modern-like cells with large dsDNA genomes. The Baltimore classes remain an integral part of the conceptual foundation of biology, providing the essential structure for the logical space of information transfer processes, which is nontrivially connected with the routes of evolution of viruses and other replicators.
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Veluthambi K, Sunitha S. Targets and Mechanisms of Geminivirus Silencing Suppressor Protein AC2. Front Microbiol 2021; 12:645419. [PMID: 33897657 PMCID: PMC8062710 DOI: 10.3389/fmicb.2021.645419] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 03/10/2021] [Indexed: 11/13/2022] Open
Abstract
Geminiviruses are plant DNA viruses that infect a wide range of plant species and cause significant losses to economically important food and fiber crops. The single-stranded geminiviral genome encodes a small number of proteins which act in an orchestrated manner to infect the host. The fewer proteins encoded by the virus are multifunctional, a mechanism uniquely evolved by the viruses to balance the genome-constraint. The host-mediated resistance against incoming virus includes post-transcriptional gene silencing, transcriptional gene silencing, and expression of defense responsive genes and other cellular regulatory genes. The pathogenicity property of a geminiviral protein is linked to its ability to suppress the host-mediated defense mechanism. This review discusses what is currently known about the targets and mechanism of the viral suppressor AC2/AL2/transcriptional activator protein (TrAP) and explore the biotechnological applications of AC2.
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Affiliation(s)
- Karuppannan Veluthambi
- Department of Plant Biotechnology, School of Biotechnology, Madurai Kamaraj University, Madurai, India
| | - Sukumaran Sunitha
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, United States
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Sun R, Han J, Zheng L, Qu F. The AC2 Protein of a Bipartite Geminivirus Stimulates the Transcription of the BV1 Gene through Abscisic Acid Responsive Promoter Elements. Viruses 2020; 12:v12121403. [PMID: 33297325 PMCID: PMC7762296 DOI: 10.3390/v12121403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 12/01/2020] [Accepted: 12/04/2020] [Indexed: 12/29/2022] Open
Abstract
Geminiviruses possess single-stranded, circular DNA genomes and control the transcription of their late genes, including BV1 of many bipartite begomoviruses, through transcriptional activation by the early expressing AC2 protein. DNA binding by AC2 is not sequence-specific; hence, the specificity of AC2 activation is thought to be conferred by plant transcription factors (TFs) recruited by AC2 in infected cells. However, the exact TFs AC2 recruits are not known for most viruses. Here, we report a systematic examination of the BV1 promoter (PBV1) of the mungbean yellow mosaic virus (MYMV) for conserved promoter motifs. We found that MYMV PBV1 contains three abscisic acid (ABA)-responsive elements (ABREs) within its first 70 nucleotides. Deleting these ABREs, or mutating them all via site-directed mutagenesis, abolished the capacity of PBV1 to respond to AC2-mediated transcriptional activation. Furthermore, ABRE and other related ABA-responsive elements were prevalent in more than a dozen Old World begomoviruses we inspected. Together, these findings suggest that ABA-responsive TFs may be recruited by AC2 to BV1 promoters of these viruses to confer specificity to AC2 activation. These observations are expected to guide the search for the actual TF(s), furthering our understanding of the mechanisms of AC2 action.
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Affiliation(s)
| | | | | | - Feng Qu
- Correspondence: ; Tel.: +1-330-263-3835
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Arif M, Atta S, Bashir MA, Hussain A, Khan MI, Farooq S, Hannan A, Islam SU, Umar UUD, Khan M, Lin W, Hashem M, Alamri S, Wu Z. Molecular characterization and RSV Co-infection of Nicotiana benthamiana with three distinct begomoviruses. Methods 2020; 183:43-49. [PMID: 31759050 DOI: 10.1016/j.ymeth.2019.11.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 11/10/2019] [Accepted: 11/16/2019] [Indexed: 12/31/2022] Open
Abstract
Geminiviruses constitute a family of plant viruses with characteristic twinned quasi-icosahedral virions and a small circular DNA genome. Geminiviruses, especially begomoviruses, cause substantial economic losses in tropical and subtropical regions globally. Geminiviruses use the host's transcriptional mechanisms to synthesize their mRNAs. They are considered as an attractive model to understand the transcription mechanism of their host plants. Experiments were conducted to identify transcriptional start sites (TSSs) of the three begomoviruses, i.e., Cotton leaf curl Multan virus (CLCuMuV), Corchorus yellow vein virus (CoYVV), and Ramie mosaic virus (RamV). We first rub-inoculated Rice stripe tenuivirus (RSV), a segmented negative-sense RNA virus that uses cap-snatching to produce capped viral mRNAs, into N. benthamiana. After the inoculation, RSV-infected N. benthamiana were super-infected by CoYVV, CLCuMuV, or RamV, respectively. The capped-RNA leaders snatched by RSV were obtained by determining the 5'-ends of RSV mRNA with high throughput sequencing. Afterwards, snatched capped-RNA leaders of RSV were mapped onto the genome of each begomovirus and those matching the begomoviral genome were considered to come from the 5' ends of assumed begomoviral mRNAs. In this way, TSSs of begomoviruses were obtained. After mapping these TSSs onto the genome of the respective begomovirus, it was found very commonly that a begomovirus can use many different TSSs to transcribe the same gene, producing many different mRNA isoforms containing the corresponding open reading frames (ORFs).
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Affiliation(s)
- Muhammad Arif
- Fujian Province Key Laboratory of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China; Department of Plant Protection, Faculty of Agricultural Sciences, Ghazi University, Dera Ghazi Khan, Punjab 32200, Pakistan; Department of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China.
| | - Sagheer Atta
- Department of Plant Protection, Faculty of Agricultural Sciences, Ghazi University, Dera Ghazi Khan, Punjab 32200, Pakistan
| | - Muhammad Amjad Bashir
- Department of Plant Protection, Faculty of Agricultural Sciences, Ghazi University, Dera Ghazi Khan, Punjab 32200, Pakistan
| | - Ansar Hussain
- Department of Plant Breeding and Genetics, Faculty of Agricultural Sciences, Ghazi University, Dera Ghazi Khan, Punjab 32200, Pakistan
| | - Muhammad Ifnan Khan
- Department of Plant Breeding and Genetics, Faculty of Agricultural Sciences, Ghazi University, Dera Ghazi Khan, Punjab 32200, Pakistan
| | - Shahid Farooq
- Department of Plant Protection, Faculty of Agriculture, Harran University, Sanliurfa 63200, Turkey
| | - Abdul Hannan
- Department of Botany, Ghazi University, Dera Ghazi Khan, Punjab 32200, Pakistan
| | - Saif Ul Islam
- Department of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Ummad Ud Din Umar
- Department of Plant Pathology, Bahauddin Zakariya University, Multan, Punjab 60800, Pakistan
| | - Mehran Khan
- Department of Plant Protection, Faculty of Agricultural Sciences, Ghazi University, Dera Ghazi Khan, Punjab 32200, Pakistan
| | - Wenzhong Lin
- Fujian Province Key Laboratory of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China; Department of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Mohamed Hashem
- King Khalid University, College of Science, Department of Biology, Abha 61413, Saudi Arabia; Assiut University, Faculty of Science, Botany and Microbiology Department, Assiut, Egypt
| | - Saad Alamri
- King Khalid University, College of Science, Department of Biology, Abha 61413, Saudi Arabia; Research Center for Advanced Materials Science (RCAMS), King Khalid University, Abha 61413, Saudi Arabia
| | - Zujian Wu
- Fujian Province Key Laboratory of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China; Department of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China.
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Vinoth Kumar R, Shivaprasad PV. Plant-virus-insect tritrophic interactions: insights into the functions of geminivirus virion-sense strand genes. Proc Biol Sci 2020; 287:20201846. [PMID: 33049166 DOI: 10.1098/rspb.2020.1846] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The genome of the plant-infecting viruses in the family Geminiviridae is composed of one or two circular single stranded DNA of approximately 2.7-5.2 kb in length. These viruses have emerged as the most devastating pathogen infecting a large number of crops and weeds across the continents. They code for fewer open reading frames (ORFs) through the generation of overlapping transcripts derived from the bidirectional viral promoters. Members of geminiviruses code for up to four ORFs in the virion-sense strand, and their gene expression is regulated by various cis-elements located at their promoters in the intergenic region. These viral proteins perform multiple functions at every stage of the viral life cycle such as virus transport, insect-mediated virus transmission and suppression of host defence. They impede the host's multi-layered antiviral mechanisms including gene silencing (at transcriptional and post-transcriptional levels) and hypersensitive response. This review summarizes the essential role of virion-sense strand encoded proteins in transport of viral genomes within and between plant cells, countering defence in hosts (both plants and the insects), and also in the ubiquitous role in vector-mediated transmission. We highlight the significance of their pro-viral activities in manipulating host-derived innate immune responses and the interaction with whitefly-derived proteins. We also discuss the current knowledge on virus replication and transcription within the insect body.
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Affiliation(s)
- R Vinoth Kumar
- National Centre for Biological Sciences (NCBS), Tata Institute of Fundamental Research (TIFR), GKVK campus, Bengaluru 560065, Karnataka, India
| | - P V Shivaprasad
- National Centre for Biological Sciences (NCBS), Tata Institute of Fundamental Research (TIFR), GKVK campus, Bengaluru 560065, Karnataka, India
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Chen ZQ, Zhao JH, Chen Q, Zhang ZH, Li J, Guo ZX, Xie Q, Ding SW, Guo HS. DNA Geminivirus Infection Induces an Imprinted E3 Ligase Gene to Epigenetically Activate Viral Gene Transcription. THE PLANT CELL 2020; 32:3256-3272. [PMID: 32769133 PMCID: PMC7534479 DOI: 10.1105/tpc.20.00249] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 07/02/2020] [Accepted: 08/04/2020] [Indexed: 05/03/2023]
Abstract
Flowering plants and mammals contain imprinted genes that are primarily expressed in the endosperm and placenta in a parent-of-origin manner. In this study, we show that early activation of the geminivirus genes C2 and C3 in Arabidopsis (Arabidopsis thaliana) plants, encoding a viral suppressor of RNA interference and a replication enhancer protein, respectively, is correlated with the transient vegetative expression of VARIANT IN METHYLATION5 (VIM5), an endosperm imprinted gene that is conserved in diverse plant species. VIM5 is a ubiquitin E3 ligase that directly targets the DNA methyltransferases MET1 and CMT3 for degradation by the ubiquitin-26S proteasome proteolytic pathway. Infection with Beet severe curly top virus induced VIM5 expression in rosette leaf tissues, possibly via the expression of the viral replication initiator protein, leading to the early activation of C2 and C3 coupled with reduced symmetric methylation in the C2-3 promoter and the onset of disease symptoms. These findings demonstrate how this small DNA virus recruits a host imprinted gene for the epigenetic activation of viral gene transcription. Our findings reveal a distinct strategy used by plant pathogens to exploit the host machinery in order to inhibit methylation-mediated defense responses when establishing infection.
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Affiliation(s)
- Zhong-Qi Chen
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, CAS Center for Excellence in Biotic Interactions, University of the Chinese Academy of Sciences, Beijing 100049, China
- Vector-Borne Virus Research Center, State Key Laboratory for Ecological Pest Control of Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jian-Hua Zhao
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, CAS Center for Excellence in Biotic Interactions, University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Qian Chen
- State Key Laboratory of Plant Genomics, Institute of Genetics and Development Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhong-Hui Zhang
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Science, South China Normal University, Guangzhou 510631, China
| | - Jie Li
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, CAS Center for Excellence in Biotic Interactions, University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Zhong-Xin Guo
- Vector-Borne Virus Research Center, State Key Laboratory for Ecological Pest Control of Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Qi Xie
- State Key Laboratory of Plant Genomics, Institute of Genetics and Development Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Shou-Wei Ding
- Department of Microbiology and Plant Pathology, Institute for Integrative Genome Biology, University of California, Riverside, California 92521
| | - Hui-Shan Guo
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, CAS Center for Excellence in Biotic Interactions, University of the Chinese Academy of Sciences, Beijing 100049, China
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17
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Mahmoudieh M, Noor MRM, Harikrishna JA, Othman RY. Identification and characterization of Ageratum yellow vein Malaysia virus (AYVMV) and an associated betasatellite among begomoviruses infecting Solanum lycopersicum in Malaysia. J Appl Genet 2020; 61:619-628. [PMID: 32808206 DOI: 10.1007/s13353-020-00574-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 06/06/2020] [Accepted: 08/11/2020] [Indexed: 11/27/2022]
Abstract
The study describes results of a survey of tomato fields for the presence of begomoviruses from different regions of Peninsular Malaysia. An ORF-based (C2 and C3) study was performed to determine the distribution of begomoviruses associated with a severe leaf curl disease in tomato-growing areas of Peninsular Malaysia. Viral DNA was isolated from symptomatic tomato plants, and begomovirus association was confirmed by PCR using DNA-A degenerate primers. The C2 and C3 sequences of the putative begomoviruses were similar to two corresponded ORFs of different geographically separated strains of begomoviruses: Pepper yellow leaf curl Indonesia virus and Tomato yellow leaf curl Kanchanaburi virus. The present study also identified a unique isolate, Ageratum yellow vein Malaysia virus (AYVMV) among above mentioned survey. It has a single-stranded DNA component and its associated betasatellite. The single-stranded DNA component is consisting of 2750 nt with six open reading frames and an organization resembling that of monopartite geminiviruses. The full length of viral single-stranded DNA component genome obtained using next generation sequencing (NGS) showed the highest sequence identity (99%) with Ageratum yellow vein virus (AYVV-BA). The betasatellite component genome obtained by NGS has 1342 nt and showed the highest sequence identity (91%) with the Pepper yellow leaf curl betasatellite. Following ICTV guidelines, Ageratum yellow vein Malaysia virus was assigned the abbreviation AYVMV with sequence and phylogenetic analysis indicating that it might have evolved by recombination of two or more viral ancestors.
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Affiliation(s)
- Mohtaram Mahmoudieh
- Centre for Research in Biotechnology for Agriculture and Institute of Biological Science, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia.
| | - Mohamad Roff Mohd Noor
- Horticulture Research Centre, MARDI Headquarters, P.O.Box 12301, GPO, 50774, Kuala Lumpur, Malaysia
| | - Jennifer Ann Harikrishna
- Centre for Research in Biotechnology for Agriculture and Institute of Biological Science, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Rofina Yasmin Othman
- Centre for Research in Biotechnology for Agriculture and Institute of Biological Science, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia
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Beam K, Ascencio-Ibáñez JT. Geminivirus Resistance: A Minireview. FRONTIERS IN PLANT SCIENCE 2020; 11:1131. [PMID: 32849693 PMCID: PMC7396689 DOI: 10.3389/fpls.2020.01131] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 07/10/2020] [Indexed: 05/04/2023]
Abstract
A continuing challenge to crop production worldwide is the spectrum of diseases caused by geminiviruses, a large family of small circular single-stranded DNA viruses. These viruses are quite diverse, some containing mono- or bi-partite genomes, and infecting a multitude of monocot and dicot plants. There are currently many efforts directed at controlling these diseases. While some of the methods include controlling the insect vector using pesticides or genetic insect resistance (Rodríguez-López et al., 2011), this review will focus on the generation of plants that are resistant to geminiviruses themselves. Genetic resistance was traditionally found by surveying the wild relatives of modern crops for resistance loci; this method is still widely used and successful. However, the quick rate of virus evolution demands a rapid turnover of resistance genes. With better information about virus-host interactions, scientists are now able to target early stages of geminivirus infection in the host, preventing symptom development and viral DNA accumulation.
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Mishra GP, Dikshit HK, S. V. R, Tripathi K, Kumar RR, Aski M, Singh A, Roy A, Priti, Kumari N, Dasgupta U, Kumar A, Praveen S, Nair RM. Yellow Mosaic Disease (YMD) of Mungbean ( Vigna radiata (L.) Wilczek): Current Status and Management Opportunities. FRONTIERS IN PLANT SCIENCE 2020; 11:918. [PMID: 32670329 PMCID: PMC7327115 DOI: 10.3389/fpls.2020.00918] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 06/04/2020] [Indexed: 03/30/2024]
Abstract
Globally, yellow mosaic disease (YMD) remains a major constraint of mungbean production, and management of this deadly disease is still the biggest challenge. Thus, finding ways to manage YMD including development of varieties possessing resistance against mungbean yellow mosaic virus (MYMV) and mungbean yellow mosaic India virus (MYMIV) is a research priority for mungbean crop. Characterization of YMD resistance using various advanced molecular and biochemical approaches during plant-virus interactions has unfolded a comprehensive network of pathogen survival, disease severity, and the response of plants to pathogen attack, including mechanisms of YMD resistance in mungbean. The biggest challenge in YMD management is the effective utilization of an array of information gained so far, in an integrated manner for the development of genotypes having durable resistance against yellow mosaic virus (YMV) infection. In this backdrop, this review summarizes the role of various begomoviruses, its genomic components, and vector whiteflies, including cryptic species in the YMD expression. Also, information about the genetics of YMD in both mungbean and blackgram crops is comprehensively presented, as both the species are crossable, and same viral strains are also found affecting these crops. Also, implications of various management strategies including the use of resistance sources, the primary source of inoculums and vector management, wide-hybridization, mutation breeding, marker-assisted selection (MAS), and pathogen-derived resistance (PDR) are thoroughly discussed. Finally, the prospects of employing various powerful emerging tools like translational genomics, and gene editing using CRISPR/Cas9 are also highlighted to complete the YMD management perspective in mungbean.
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Affiliation(s)
- Gyan P. Mishra
- Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Harsh K. Dikshit
- Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Ramesh S. V.
- Division of Physiology, Biochemistry and PHT, ICAR-Central Plantation, Kasaragod, India
| | - Kuldeep Tripathi
- Germplasm Evaluation Division, ICAR-National Bureau of Plant Genetic Resources, New Delhi, India
| | - Ranjeet R. Kumar
- Division of Biochemistry, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Muraleedhar Aski
- Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Akanksha Singh
- Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Anirban Roy
- Division of Plant Pathology, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Priti
- Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Nikki Kumari
- Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Uttarayan Dasgupta
- Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Atul Kumar
- Division of Seed Science and Technology, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Shelly Praveen
- Division of Biochemistry, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Ramakrishnan M. Nair
- World Vegetable Center, South Asia, ICRISAT Campus, Patancheru, Hyderabad, India
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Sun M, Jiang K, Li C, Du J, Li M, Ghanem H, Wu G, Qing L. Tobacco curly shoot virus C3 protein enhances viral replication and gene expression in Nicotiana benthamiana plants. Virus Res 2020; 281:197939. [PMID: 32198077 DOI: 10.1016/j.virusres.2020.197939] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/10/2020] [Accepted: 03/14/2020] [Indexed: 11/24/2022]
Abstract
Geminiviruses are single-stranded DNA viruses that cause devastating diseases in many crops worldwide. The replication enhancer proteins (REn), encoded by the C3 (AC3, and AL3) ORFs of geminiviruses, have critical roles in viral DNA accumulation and symptom development in infected plants. In the current study, we have constructed an infectious clone of the Tobacco curly shoot virus (TbCSV) C3 mutant, TbCSVΔC3, that contains two start codon mutations that abrogated C3 ORF expression, but did not alter the amino acid sequence of the C2 ORF. As predicted, the absence of the C3 protein reduced TbCSV DNA accumulation, and over-expression of the C3 protein enhanced TbCSV DNA accumulation in infected leaves of Nicotiana benthamiana. The C3 mutation reduced the expression levels of both virion- and complementary-sense TbCSV genes whereas over-expression of the C3 protein increased TbCSV gene expression. Furthermore, the expression of the wild-type and site-directed mutants of C3 proteins using the potato virus X (PVX) system showed that Y93A mutation reduced the replication enhancement activity of the C3 protein in N. benthamiana. All the available evidence demonstrates that the C3 protein is tightly coupled with TbCSV DNA accumulation. However, the TbCSVΔC3 mutant was nearly as infectious in N. benthamiana as TbCSVWT and only had slightly delayed and attenuated symptom expression. Our findings demonstrate that TbCSV C3 protein enhances viral replication and gene expression, but has only moderate effects on symptom development in N. benthamiana.
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Affiliation(s)
- Miao Sun
- Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing, 400716, China.
| | - Kairong Jiang
- Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing, 400716, China.
| | - Chunji Li
- Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing, 400716, China.
| | - Jiang Du
- Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing, 400716, China.
| | - Mingjun Li
- Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing, 400716, China.
| | - Hussein Ghanem
- Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing, 400716, China.
| | - Gentu Wu
- Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing, 400716, China.
| | - Ling Qing
- Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing, 400716, China.
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Patwa N, Chatterjee C, Basak J. Differential responses of Phaseolus vulgaris cultivars following mungbean yellow mosaic India virus infection. PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2020; 26:817-828. [PMID: 32255942 PMCID: PMC7113345 DOI: 10.1007/s12298-019-00741-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 09/16/2019] [Accepted: 11/25/2019] [Indexed: 05/31/2023]
Abstract
Phaseolus vulgaris, commonly known as French bean is a vital leguminous crop worldwide and India stood 1st rank in dry bean and 4th rank in green bean production worldwide (FAOSTAT 2017). However, this production is severely affected by Mungbean yellow mosaic India virus (MYMIV) infection. Hence it is very important to identify MYMIV tolerant P. vulgaris cultivars. MYMIV infection results in the production of reactive oxygen species and plant cells have evolved complex defense mechanisms at different levels to overcome the damage. Our study for the first time focused on the changes at the morphological and biochemical level, as well as on the relative quantification of MYMIV genes in nine cultivars of P. vulgaris after MYMIV infection. Highest growth and the highest accumulation of four antioxidants of cv. 'Anupam' after MYMIV infection, established that cv. 'Anupam' was less affected by MYMIV infection amongst all nine cultivars. Relative quantification studies also correlated well with these results. Additionally, there is a consistent level of photosynthetic pigments content in mock- and MYMIV-treated seedlings of cv. 'Anupam' over early infection period. Combining all the results we conclude that cv. 'Anupam' is a MYMIV tolerant cultivar.
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Affiliation(s)
- Nisha Patwa
- Department of Biotechnology, Visva-Bharati, Siksha Bhavana, Santiniketan, West Bengal 731235 India
- Present Address: Horticultural Insects Research Laboratory, USDA-ARS, Application Technology Research Unit, 1680 Madison Ave., Wooster, OH 44691 USA
| | - Chitra Chatterjee
- Department of Biotechnology, Visva-Bharati, Siksha Bhavana, Santiniketan, West Bengal 731235 India
| | - Jolly Basak
- Department of Biotechnology, Visva-Bharati, Siksha Bhavana, Santiniketan, West Bengal 731235 India
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22
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Piedra-Aguilera Á, Jiao C, Luna AP, Villanueva F, Dabad M, Esteve-Codina A, Díaz-Pendón JA, Fei Z, Bejarano ER, Castillo AG. Integrated single-base resolution maps of transcriptome, sRNAome and methylome of Tomato yellow leaf curl virus (TYLCV) in tomato. Sci Rep 2019; 9:2863. [PMID: 30814535 PMCID: PMC6393547 DOI: 10.1038/s41598-019-39239-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 01/16/2019] [Indexed: 11/09/2022] Open
Abstract
Geminiviruses are plant ssDNA viruses that replicate through dsDNA intermediates and form minichromosomes which carry the same epigenetic marks as the host chromatin. During the infection, geminiviruses are targets of the post-transcriptional and transcriptional gene silencing machinery. To obtain insights into the connection between virus-derived small RNAs (vsRNAs), viral genome methylation and gene expression, we obtained the transcriptome, sRNAome and methylome from the geminivirus Tomato yellow leaf curl virus-infected tomato plants. The results showed accumulation of transcripts just at the viral ORFs, while vsRNAs spanned the entire genome, showing a prevalent accumulation at regions where the viral ORFs overlapped. The viral genome was not homogenously methylated showing two highly methylated regions located in the C1 ORF and around the intergenic region (IR). The compilation of those results showed a partial correlation between vsRNA accumulation, gene expression and DNA methylation. We could distinguish different epigenetic scenarios along the viral genome, suggesting that in addition to its function as a plant defence mechanism, DNA methylation could have a role in viral gene regulation. To our knowledge, this is the first report that shows integrative single-nucleotide maps of DNA methylation, vsRNA accumulation and gene expression from a plant virus.
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Affiliation(s)
- Álvaro Piedra-Aguilera
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora (IHSM-UMA-CSIC), Área de Genética, Facultad de Ciencias, Universidad de Málaga, E-29071, Málaga, Spain
| | - Chen Jiao
- Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, New York, USA
| | - Ana P Luna
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora (IHSM-UMA-CSIC), Área de Genética, Facultad de Ciencias, Universidad de Málaga, E-29071, Málaga, Spain
| | - Francisco Villanueva
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora (IHSM-UMA-CSIC), Plant Virology group, E. E. La Mayora CSIC, Algarrobo-Costa, E-29750, Málaga, Spain
| | - Marc Dabad
- CNAG-CRG, Barcelona Institute of Science and Technology (BIST), E-08028, Barcelona, Spain
| | - Anna Esteve-Codina
- CNAG-CRG, Barcelona Institute of Science and Technology (BIST), E-08028, Barcelona, Spain.,Universitat Pompeu Fabra (UPF), E-08003, Barcelona, Spain
| | - Juan A Díaz-Pendón
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora (IHSM-UMA-CSIC), Plant Virology group, E. E. La Mayora CSIC, Algarrobo-Costa, E-29750, Málaga, Spain
| | - Zhangjun Fei
- Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, New York, USA
| | - Eduardo R Bejarano
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora (IHSM-UMA-CSIC), Área de Genética, Facultad de Ciencias, Universidad de Málaga, E-29071, Málaga, Spain
| | - Araceli G Castillo
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora (IHSM-UMA-CSIC), Área de Genética, Facultad de Ciencias, Universidad de Málaga, E-29071, Málaga, Spain.
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Vargas-Asencio J, Liou H, Perry KL, Thompson JR. Evidence for the splicing of grablovirus transcripts reveals a putative novel open reading frame. J Gen Virol 2019; 100:709-720. [PMID: 30775960 DOI: 10.1099/jgv.0.001234] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Grapevine red blotch virus (GRBV) is type member of the newly identified genus Grablovirus. It possesses a single-stranded circular DNA genome of around 3200 nucleotides encoding three open reading frames (ORFs) in both the virion sense, the V1 (CP), V2 and V3, and complementary sense, C1 (RepA), C2 and C3. As shown for members of the genus Mastrevirus, the C1 and C2 ORFs are predicted to fuse through splicing to form a replication-associated protein (Rep). Data obtained using high-throughput sequencing (RNA-Seq) of three RNA-enriched populations, extracted from GRBV-infected grapevine (Vitis vinifera), confirmed the presence of the predicted C1-C2 intron (nts 2288-2450), but in addition identified a larger virion-sense intron (nts 251-589) spanning the V2 ORF. Evidence for both introns in a number of isolates was supported by bioinformatic analysis of publicly available datasets (n=20). These observations were further supported by RT-PCR analyses in both GRBV-infected grapevine and transient expression assays where GRBV genome segments were agro-inoculated onto Nicotiana benthamiana. The donor site of the virion-sense intron is located within two small ORFs, V0 and V02, while the acceptor site is two-thirds along the V2 ORF. Splicing at these positions is predicted to delete the N terminus of the encoded V2 protein. Comparative analyses of full-length GRBV sequences and the related tentative grabloviruses Prunus geminivirus A and wild Vitis virus 1 support the existence of both introns and V0. The probable regulatory role of these introns in the GRBV infection cycle is discussed.
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Affiliation(s)
- José Vargas-Asencio
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University College of Agriculture and Life Sciences, Ithaca, NY, 14853, USA
| | - Harris Liou
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University College of Agriculture and Life Sciences, Ithaca, NY, 14853, USA
| | - Keith L Perry
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University College of Agriculture and Life Sciences, Ithaca, NY, 14853, USA
| | - Jeremy R Thompson
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University College of Agriculture and Life Sciences, Ithaca, NY, 14853, USA
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Cantú-Iris M, Pastor-Palacios G, Mauricio-Castillo JA, Bañuelos-Hernández B, Avalos-Calleros JA, Juárez-Reyes A, Rivera-Bustamante R, Argüello-Astorga GR. Analysis of a new begomovirus unveils a composite element conserved in the CP gene promoters of several Geminiviridae genera: Clues to comprehend the complex regulation of late genes. PLoS One 2019; 14:e0210485. [PMID: 30673741 PMCID: PMC6344024 DOI: 10.1371/journal.pone.0210485] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 12/25/2018] [Indexed: 12/01/2022] Open
Abstract
A novel bipartite begomovirus, Blechum interveinal chlorosis virus (BleICV), was characterized at the genome level. Comparative analyses revealed that BleICV coat protein (CP) gene promoter is highly divergent from the equivalent region of other begomoviruses (BGVs), with the single exception of Tomato chino La Paz virus (ToChLPV) with which it shares a 23-bp phylogenetic footprint exhibiting dyad symmetry. Systematic examination of the homologous CP promoter segment of 132 New World BGVs revealed the existence of a quasi-palindromic DNA segment displaying a strongly conserved ACTT-(N7)-AAGT core. The spacer sequence between the palindromic motifs is constant in length, but its sequence is highly variable among viral species, presenting a relaxed consensus (TT)GGKCCCY, which is similar to the Conserved Late Element or CLE (GTGGTCCC), a putative TrAP-responsive element. The homologous CP promoter region of Old World BGVs exhibited a distinct organization, with the putative TATA-box overlapping the left half of the ACTT-N7 composite element. Similar CP promoter sequences, dubbed "TATA-associated composite element" or TACE, were found in viruses belonging to different Geminiviridae genera, hence hinting unsuspected evolutionary relationships among those lineages. To get cues about the TACE function, the regulatory function of the CLE was explored in distinct experimental systems. Transgenic tobacco plants harboring a GUS reporter gene driven by a promoter composed by CLE multimers expressed high beta-glucuronidase activity in absence of viral factors, and that expression was increased by begomovirus infection. On the other hand, the TrAP-responsiveness of a truncated CP promoter of Tomato golden mosaic virus (TGMV) was abolished by site-directed mutation of the only CLE present in it, whereas the artificial addition of one CLE to the -125 truncated promoter strongly enhanced the transactivation level in tobacco protoplasts. These results indicate that the CLE is a TrAP-responsive element, hence providing valuable clues to interpret the recurrent association of the CLE with the TACE. On the basis of the aforesaid direct evidences and the insights afforded by the extensive comparative analysis of BleICV CP promoter, we propose that the TACE might be involved in the TrAP-mediated derepression of CP gene in vascular tissues.
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Affiliation(s)
- Mariana Cantú-Iris
- División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica A. C., San Luis Potosí, SLP, México
| | - Guillermo Pastor-Palacios
- CONACYT–CIIDZA–Instituto Potosino de Investigación Científica y Tecnológica A. C., San Luis Potosí, SLP, México
| | | | - Bernardo Bañuelos-Hernández
- Facultad de Agronomía y Veterinaria, Universidad De La Salle Bajio, Avenida Universidad 602, Lomas del campestre, León Guanajuato, México
| | - Jesús Aarón Avalos-Calleros
- División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica A. C., San Luis Potosí, SLP, México
| | - Alejandro Juárez-Reyes
- División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica A. C., San Luis Potosí, SLP, México
| | - Rafael Rivera-Bustamante
- Departamento de Ingeniería Genética de Plantas, Centro de Investigación y de Estudios Avanzados del IPN, Irapuato, Gto., México
| | - Gerardo R. Argüello-Astorga
- División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica A. C., San Luis Potosí, SLP, México
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25
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Vaca-Vaca JC, Carrasco-Lozano EC, Lopez-Lopez K. Evaluación del potencial biotecnológico de un promotor derivado del virus de la distorsión de la hoja de maracuyá (PLDV), un begomovirus que infecta maracuyá. REVISTA COLOMBIANA DE BIOTECNOLOGÍA 2019. [DOI: 10.15446/rev.colomb.biote.v21n1.77636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Los avances biotecnológicos en plantas requieren la bioprospección de nuevos promotores para la expresión de genes de interésagronómico, en particular, es necesario caracterizar nuevos promotores con expresión tejido específica. El objetivo de esta investi-gación fue evaluar la actividad de expresión del promotor del gen AV1que codifica para la proteína de la cápside (CP) del virus de la distorsión de la hoja de maracuyá (Passion fruit leaf distortion virus,PLDV) mediante ensayos transitorios de biobalística de baja presión. Se realizó un análisis de la región promotora del gen AV1empleando herramientas bioinformáticas. Se construyó una fu-sión traduccional (CP-PLDV-GUS), que porta la región promotora del gen AV1de PLDV fusionada al gen reportero uidA(GUS). CP-PLDV-GUS fue bombardeado sobre hojas de plántulas de tabaco cultivadas in vitro empleando una pistola de genes. Como control positivo se utilizó el plásmido pBI121 que porta el gen GUS bajo el control del promotor 35S de CaMV. Se llevaron a cabo 11 re-peticiones, donde la unidad experimental fue la hoja y la variable de respuesta, la expresión transitoria del gen GUS representado por el número de puntos azules observados en las hojas bombardeadas. Como resultado, el análisis estadístico no paramétrico demostró que existe evidencia muestral suficiente para confirmar que, tanto el promotor AV1del PLDV y 35S de CaMV presentan una actividad de expresión semejante. Finalmente, el promotor del gen AV1de PLDV mostró una fuerte actividad de expresión del gen reportero en las células del mesófilo de las hojas, el cual podría ser usado para conferir expresión tejido específica enplantas transgénicas
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26
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Kushawaha AK, Dasgupta I. Infectivity of cloned begomoviral DNAs: an appraisal. Virusdisease 2018; 30:13-21. [PMID: 31143828 DOI: 10.1007/s13337-018-0453-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Accepted: 04/18/2018] [Indexed: 11/28/2022] Open
Abstract
Infectivity of cloned begomoviral DNAs is an important criterion to establish the etiology of the disease it causes, to study viral gene functions and host-virus interactions. Three main methods have been employed to study infectivity; mechanical inoculation with cloned viral DNA using abrasives, Agrobacterium-mediated inoculation (agroinoculation) of cloned viral DNA and bombardment using microprojectiles coated with cloned viral DNA (biolistics). Each method has its own advantages and disadvantages and the adoption of one over the other for demonstrating infectivity depends on various factors. This review compares the various features associated with the above three methods.
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Affiliation(s)
- Akhilesh Kumar Kushawaha
- Department of Plant Molecular Biology, University of Delhi South Campus, Benito Juarez Road, New Delhi, 110021 India
| | - Indranil Dasgupta
- Department of Plant Molecular Biology, University of Delhi South Campus, Benito Juarez Road, New Delhi, 110021 India
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27
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Vaghi Medina CG, Teppa E, Bornancini VA, Flores CR, Marino-Buslje C, López Lambertini PM. Tomato Apical Leaf Curl Virus: A Novel, Monopartite Geminivirus Detected in Tomatoes in Argentina. Front Microbiol 2018; 8:2665. [PMID: 29375528 PMCID: PMC5770407 DOI: 10.3389/fmicb.2017.02665] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 12/21/2017] [Indexed: 01/27/2023] Open
Abstract
Plant viruses that are members of the Geminiviridae family have circular single-stranded DNA (ssDNA) genome and are responsible for major crop diseases worldwide. We have identified and characterized a novel monopartite geminivirus infecting tomato in Argentina. The full-length genome was cloned and sequenced. The genome-wide pairwise identity calculation that resulted in a maximum of 63% identity with all of other known geminiviruses indicated that it is a new geminivirus species. Biolistic infected plants presented interveinal yellowing, apical leaf curling and extreme root hypotrophy. Thus, the name proposed for this species is tomato apical leaf curl virus (ToALCV). The phylogenetic inferences suggested different evolutionary relationships for the replication-associated protein (Rep) and the coat protein (CP). Besides, the sequence similarity network (SSN) protein analyses showed that the complementary-sense gene products (RepA, Rep and C3) are similar to capulavirus while the viron-sense gene products (CP, MP and V3) are similar to topocuvirus, curtovirus and becurtovirus. Based on the data presented, ToALCV genome appears to have “modular organization” supported by its recombination origin. Analyses of the specificity-determining positions (SDPs) of the CP of geminiviruses defined nine subgroups that include geminiviruses that share the same type of insect vector. Our sequences were clustered with the sequences of topocuvirus, whose vector is the treehopper, Micrutalis malleifera. Also, a set of the highest scored amino acid residues was predicted for the CP, which could determine differences in virus transmission specificity. We predict that a treehopper could be the vector of ToALCV, but transmission assays need to be performed to confirm this. Given everything we demonstrate in this paper, ToALCV can be considered a type member of a new putative genus of the Geminiviridae family.
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Affiliation(s)
- Carlos G Vaghi Medina
- Area de Interacción Planta-Patógeno-Vector, Instituto de Patología Vegetal, Centro de Investigaciónes Agropecuarias, Instituto Nacional de Tecnología Agropecuaria, Córdoba, Argentina
| | - Elin Teppa
- Instituto de Investigaciones Bioquímicas de Buenos Aires, Fundación Instituto Leloir, Buenos Aires, Argentina
| | - Verónica A Bornancini
- Area de Interacción Planta-Patógeno-Vector, Instituto de Patología Vegetal, Centro de Investigaciónes Agropecuarias, Instituto Nacional de Tecnología Agropecuaria, Córdoba, Argentina
| | - Ceferino R Flores
- Estación Experimental Agropecuaria Yuto, Instituto Nacional de Tecnología Agropecuaria, Yuto, Argentina
| | - Cristina Marino-Buslje
- Instituto de Investigaciones Bioquímicas de Buenos Aires, Fundación Instituto Leloir, Buenos Aires, Argentina
| | - Paola M López Lambertini
- Area de Interacción Planta-Patógeno-Vector, Instituto de Patología Vegetal, Centro de Investigaciónes Agropecuarias, Instituto Nacional de Tecnología Agropecuaria, Córdoba, Argentina
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28
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Lin W, Qiu P, Jin J, Liu S, Ul Islam S, Yang J, Zhang J, Kormelink R, Du Z, Wu Z. The Cap Snatching of Segmented Negative Sense RNA Viruses as a Tool to Map the Transcription Start Sites of Heterologous Co-infecting Viruses. Front Microbiol 2017; 8:2519. [PMID: 29312219 PMCID: PMC5735111 DOI: 10.3389/fmicb.2017.02519] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 12/04/2017] [Indexed: 01/06/2023] Open
Abstract
Identification of the transcription start sites (TSSs) of a virus is of great importance to understand and dissect the mechanism of viral genome transcription but this often requires costly and laborious experiments. Many segmented negative-sense RNA viruses (sNSVs) cleave capped leader sequences from a large variety of mRNAs and use these cleaved leaders as primers for transcription in a conserved process called cap snatching. The recent developments in high-throughput sequencing have made it possible to determine most, if not all, of the capped RNAs snatched by a sNSV. Here, we show that rice stripe tenuivirus (RSV), a plant-infecting sNSV, co-infects Nicotiana benthamiana with two different begomoviruses and snatches capped leader sequences from their mRNAs. By determining the 5' termini of a single RSV mRNA with high-throughput sequencing, the 5' ends of almost all the mRNAs of the co-infecting begomoviruses could be identified and mapped on their genomes. The findings in this study provide support for the using of the cap snatching of sNSVs as a tool to map viral TSSs.
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Affiliation(s)
- Wenzhong Lin
- Fujian Province Key Laboratory of Plant Virology, Plant Protection College, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Ping Qiu
- Fujian Province Key Laboratory of Plant Virology, Plant Protection College, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jing Jin
- Fujian Province Key Laboratory of Plant Virology, Plant Protection College, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Shunmin Liu
- Fujian Province Key Laboratory of Plant Virology, Plant Protection College, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Saif Ul Islam
- Fujian Province Key Laboratory of Plant Virology, Plant Protection College, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jinguang Yang
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao, China
| | - Jie Zhang
- Fujian Province Key Laboratory of Plant Virology, Plant Protection College, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Richard Kormelink
- Laboratory of Virology, Wageningen University and Research Centre, Wageningen, Netherlands
| | - Zhenguo Du
- Fujian Province Key Laboratory of Plant Virology, Plant Protection College, Fujian Agriculture and Forestry University, Fuzhou, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fuzhou, China
| | - Zujian Wu
- Fujian Province Key Laboratory of Plant Virology, Plant Protection College, Fujian Agriculture and Forestry University, Fuzhou, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fuzhou, China
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30
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Kumar S, Tanti B, Patil BL, Mukherjee SK, Sahoo L. RNAi-derived transgenic resistance to Mungbean yellow mosaic India virus in cowpea. PLoS One 2017; 12:e0186786. [PMID: 29077738 PMCID: PMC5659608 DOI: 10.1371/journal.pone.0186786] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 10/06/2017] [Indexed: 11/21/2022] Open
Abstract
Cowpea is an important grain legume crop of Africa, Latin America, and Southeast Asia. Leaf curl and golden mosaic diseases caused by Mungbean yellow mosaic India virus (MYMIV) have emerged as most devastating viral diseases of cowpea in Southeast Asia. In this study, we employed RNA interference (RNAi) strategy to control cowpea-infecting MYMIV. For this, we generated transgenic cowpea plants harbouring three different intron hairpin RNAi constructs, containing the AC2, AC4 and fusion of AC2 and AC4 (AC2+AC4) of seven cowpea-infecting begomoviruses. The T0 and T1 transgenic cowpea lines of all the three constructs accumulated transgene-specific siRNAs. Transgenic plants were further assayed up to T1 generations, for resistance to MYMIV using agro-infectious clones. Nearly 100% resistance against MYMIV infection was observed in transgenic lines, expressing AC2-hp and AC2+AC4-hp RNA, when compared with untransformed controls and plants transformed with empty vectors, which developed severe viral disease symptoms within 3 weeks. The AC4-hp RNA expressing lines displayed appearance of milder symptoms after 5 weeks of MYMIV-inoculation. Northern blots revealed a positive correlation between the level of transgene-specific siRNAs accumulation and virus resistance. The MYMIV-resistant transgenic lines accumulated nearly zero or very low titres of viral DNA. The transgenic cowpea plants had normal phenotype with no yield penalty in greenhouse conditions. This is the first demonstration of RNAi-derived resistance to MYMIV in cowpea.
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Affiliation(s)
- Sanjeev Kumar
- Department of Bioscience and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
- Department of Botany, Gauhati University, Guwahati, Assam, India
| | - Bhaben Tanti
- Department of Botany, Gauhati University, Guwahati, Assam, India
| | - Basavaprabhu L. Patil
- ICAR-National Research Centre on Plant Biotechnology, LBS Centre, IARI, Pusa Campus, New Delhi, India
| | - Sunil Kumar Mukherjee
- Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi, India
| | - Lingaraj Sahoo
- Department of Bioscience and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
- * E-mail:
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Ramesh SV, Sahu PP, Prasad M, Praveen S, Pappu HR. Geminiviruses and Plant Hosts: A Closer Examination of the Molecular Arms Race. Viruses 2017; 9:E256. [PMID: 28914771 PMCID: PMC5618022 DOI: 10.3390/v9090256] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 09/02/2017] [Accepted: 09/06/2017] [Indexed: 11/24/2022] Open
Abstract
Geminiviruses are plant-infecting viruses characterized by a single-stranded DNA (ssDNA) genome. Geminivirus-derived proteins are multifunctional and effective regulators in modulating the host cellular processes resulting in successful infection. Virus-host interactions result in changes in host gene expression patterns, reprogram plant signaling controls, disrupt central cellular metabolic pathways, impair plant's defense system, and effectively evade RNA silencing response leading to host susceptibility. This review summarizes what is known about the cellular processes in the continuing tug of war between geminiviruses and their plant hosts at the molecular level. In addition, implications for engineered resistance to geminivirus infection in the context of a greater understanding of the molecular processes are also discussed. Finally, the prospect of employing geminivirus-based vectors in plant genome engineering and the emergence of powerful genome editing tools to confer geminivirus resistance are highlighted to complete the perspective on geminivirus-plant molecular interactions.
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Affiliation(s)
- Shunmugiah V Ramesh
- ICAR-Indian Institute of Soybean Research, Indian Council of Agricultural Research, Indore 452001, India.
- Department of Plant Pathology, Washington State University, Pullman, WA 99163, USA.
| | - Pranav P Sahu
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi110067, India.
| | - Manoj Prasad
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi110067, India.
| | - Shelly Praveen
- Division of Plant Pathology, Advanced Centre for Plant Virology, ICAR-Indian Agricultural Research Institute (IARI), New Delhi 110012, India.
| | - Hanu R Pappu
- Department of Plant Pathology, Washington State University, Pullman, WA 99163, USA.
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32
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Splicing features in the expression of the complementary-sense genes of Beet curly top Iran virus. Virus Genes 2016; 53:323-327. [PMID: 28004232 DOI: 10.1007/s11262-016-1422-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 12/09/2016] [Indexed: 10/20/2022]
Abstract
Beet curly top Iran virus (BCTIV) is a distinct geminivirus which has been reported from sugar-beet-growing farms in Iran. In this study, the role of the splicing in expression of complementary-sense genes of BCTIV was studied. Total RNA was extracted from BCTIV-infected tissue, and the predicted intron position of complementary-sense mRNA transcripts was amplified by RT-PCR followed by cloning of the amplicons. Sequence confirmed that both spliced and unspliced mRNAs are synthesized by the same transcription unit. Sequence comparison showed that a 155-nt segment (intron) corresponding to nucleotides 1890-2044 of the viral genome has been removed from the latter transcript and therefore fusion of the C1:C2 genes resulted creation of a continuous reading frame for potential production of intact replication initiator protein (Rep). BCTIV intron comprises of most consensus splicing signals required for splicing in eukaryotes and several plant viruses including mastre- and capulaviruses.
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Deuschle K, Kepp G, Jeske H. Differential methylation of the circular DNA in geminiviral minichromosomes. Virology 2016; 499:243-258. [PMID: 27716464 DOI: 10.1016/j.virol.2016.09.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 09/22/2016] [Accepted: 09/24/2016] [Indexed: 10/20/2022]
Abstract
Geminiviral minichromosomes were purified to explore epigenetic modifications. The levels of methylation in their covalently closed circular DNA were examined with the help of methylation-dependent restriction (MdR). DNA with 12 superhelical turns was preferentially modified, indicating minichromosomes with 12 nucleosomes leaving an open gap. MdR digestion yielded a specific product of genomic length, which was cloned and Sanger-sequenced, or amplified following ligation-mediated rolling circle amplification and deep-sequenced (circomics). The conventional approach revealed a single cleavage product indicating specific methylations at the borders of the common region. The circomics approach identified considerably more MdR sites in a preferential distance to each other of ~200 nts, which is the DNA length in a nucleosome. They accumulated in regions of nucleosome-free gaps, but scattered also along the genomic components. These results may hint at a function in specific gene regulation, as well as in virus resistance.
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Affiliation(s)
- Kathrin Deuschle
- Institut für Biomaterialien und biomolekulare Systeme, Abteilung für Molekularbiologie und Virologie der Pflanzen, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
| | - Gabi Kepp
- Institut für Biomaterialien und biomolekulare Systeme, Abteilung für Molekularbiologie und Virologie der Pflanzen, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
| | - Holger Jeske
- Institut für Biomaterialien und biomolekulare Systeme, Abteilung für Molekularbiologie und Virologie der Pflanzen, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany.
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34
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Hipp K, Rau P, Schäfer B, Pfannstiel J, Jeske H. Translation, modification and cellular distribution of two AC4 variants of African cassava mosaic virus in yeast and their pathogenic potential in plants. Virology 2016; 498:136-148. [PMID: 27584591 DOI: 10.1016/j.virol.2016.07.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Revised: 07/05/2016] [Accepted: 07/07/2016] [Indexed: 11/29/2022]
Abstract
Plant infecting geminiviruses encode a small (A)C4 protein within the open reading frame of the replication-initiator protein. In African cassava mosaic virus, two in-frame start codons may be used for the translation of a longer and a shorter AC4 variant. Both were fused to green fluorescent protein or glutathione-S-transferase genes and expressed in fission yeast. The longer variant accumulated in discrete spots in the cytoplasm, whereas the shorter variant localized to the plasma membrane. A similar expression pattern was found in plants. A myristoylation motif may promote a targeting of the shorter variant to the plasma membrane. Mass spectrometry analysis of the yeast-expressed shorter variant detected the corresponding myristoylation. The biological relevance of the second start codon was confirmed using mutated infectious clones. Whereas mutating the first start codon had no effect on the infectivity in Nicotiana benthamiana plants, the second start codon proved to be essential.
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Affiliation(s)
- Katharina Hipp
- University of Stuttgart, Institute of Biomaterials and biomolecular Systems, Department of Molecular Biology and Plant Virology, Pfaffenwaldring 57, 70550 Stuttgart, Germany.
| | - Peter Rau
- University of Stuttgart, Institute of Biomaterials and biomolecular Systems, Department of Molecular Biology and Plant Virology, Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - Benjamin Schäfer
- University of Stuttgart, Institute of Biomaterials and biomolecular Systems, Department of Molecular Biology and Plant Virology, Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | - Jens Pfannstiel
- University of Hohenheim, Mass Spectrometry Core Facility, August-von-Hartmann-Straße 3, 70599 Stuttgart, Germany
| | - Holger Jeske
- University of Stuttgart, Institute of Biomaterials and biomolecular Systems, Department of Molecular Biology and Plant Virology, Pfaffenwaldring 57, 70550 Stuttgart, Germany
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Borah B, Zarreen F, Baruah G, Dasgupta I. Insights into the control of geminiviral promoters. Virology 2016; 495:101-11. [DOI: 10.1016/j.virol.2016.04.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 04/26/2016] [Accepted: 04/27/2016] [Indexed: 10/21/2022]
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Patil BL, Bagewadi B, Yadav JS, Fauquet CM. Mapping and identification of cassava mosaic geminivirus DNA-A and DNA-B genome sequences for efficient siRNA expression and RNAi based virus resistance by transient agro-infiltration studies. Virus Res 2015; 213:109-115. [PMID: 26581664 DOI: 10.1016/j.virusres.2015.11.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 11/05/2015] [Accepted: 11/06/2015] [Indexed: 11/30/2022]
Abstract
Geminiviruses are among the most serious pathogens of many economically important crop plants and RNA interference (RNAi) is an important strategy for their control. Although any fragment of a viral genome can be used to generate a double stranded (ds) RNA trigger, the precursor for generation of siRNAs, the exact sequence and size requirements for efficient gene silencing and virus resistance have so far not been investigated. Previous efforts to control geminiviruses by gene silencing mostly targeted AC1, the gene encoding replication-associated protein. In this study we made RNAi constructs for all the genes of both the genomic components (DNA-A and DNA-B) of African cassava mosaic virus (ACMV-CM), one of the most devastating geminiviruses causing cassava mosaic disease (CMD) in Africa. Using transient agro-infiltration studies, RNAi constructs were evaluated for their ability to trigger gene silencing against the invading virus and protection against it. The results show that the selection of the DNA target sequence is an important determinant for the amount of siRNA produced and the extent of resistance. The ACMV genes AC1, AC2, AC4 from DNA-A and BC1 from DNA-B were effective targets for RNAi-mediated resistance and their siRNA expression was higher compared to other RNAi constructs. The RNAi construct targeting AC2, the suppressor of gene silencing of ACMV-CM gave highest level of resistance in the transient studies. This is the first report of targeting DNA-B to confer resistance to a bipartite geminivirus infection.
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Affiliation(s)
- Basavaprabhu L Patil
- ICAR-National Research Centre on Plant Biotechnology, Pusa, New Delhi 110012, India; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA.
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Patil BL, Fauquet CM. Studies on differential behavior of cassava mosaic geminivirus DNA components, symptom recovery patterns, and their siRNA profiles. Virus Genes 2015; 50:474-86. [PMID: 25724177 DOI: 10.1007/s11262-015-1184-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 02/18/2015] [Indexed: 11/28/2022]
Abstract
Cassava mosaic disease caused by cassava mosaic geminiviruses (CMGs) with bipartite genome organization is a major constraint for production of cassava in the African continent and the Indian sub-continent. Currently, there are eleven recognized species of CMGs, and several diverse isolates represent them, with vast amount of sequence variability, reflecting into diversity of symptom severity/phenotypes. Here, we make a systematic effort to study the infection dynamics of several species of CMGs and their isolates. Further, we try to identify the genomic component of CMGs contributing to the manifestation of diverse patterns of symptoms and the molecular basis for the differential behavior of CMGs. The pseudo-recombination studies carried out by swapping of DNA-A and DNA-B components of the CMGs revealed that the DNA-B component significantly contributes to the symptom severity. Past studies had shown that the DNA-A component of Sri Lankan cassava mosaic virus shows monopartite feature. Thus, the ability of DNA-A component alone, to replicate and move systemically in the host plant with inherent monopartite features was investigated for all the CMGs. Geminiviruses are known to trigger gene silencing and are also its target, resulting in recovery of the host plant from viral infection. In the collection of several different CMG species and isolates we had, there was a vast variability in their recovery and non-recovery phenotypes. To understand the molecular basis of this, the origin and distribution of virus-derived small interfering RNAs were mapped across their genome and across the CMG-infected symptomatic Nicotiana benthamiana.
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Shanmugapriya G, Das SS, Veluthambi K. Transgenic tobacco plants expressing siRNA targeted against the Mungbean yellow mosaic virus transcriptional activator protein gene efficiently block the viral DNA accumulation. Virusdisease 2015; 26:55-61. [PMID: 26436122 PMCID: PMC4585057 DOI: 10.1007/s13337-015-0251-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2014] [Accepted: 03/18/2015] [Indexed: 10/23/2022] Open
Abstract
Mungbean yellow mosaic virus (MYMV) is a bipartite begomovirus that infects many pulse crops such as blackgram, mungbean, mothbean, Frenchbean, and soybean. We tested the efficacy of the transgenically expressed intron-spliced hairpin RNA gene of the transcriptional activator protein (hpTrAP) in reducing MYMV DNA accumulation. Tobacco plants transformed with the MYMV hpTrAP gene accumulated 21-22 nt siRNA. Leaf discs of the transgenic plants, agroinoculated with the partial dimers of MYMV, displayed pronounced reduction in MYMV DNA accumulation. Thus, silencing of the TrAP gene, a suppressor of gene silencing, emerged as an effective strategy to control MYMV.
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Affiliation(s)
- Gnanasekaran Shanmugapriya
- Department of Plant Biotechnology, School of Biotechnology, Madurai Kamaraj University, Madurai, 625021 Tamil Nadu India
| | - Sudhanshu Sekhar Das
- Department of Plant Biotechnology, School of Biotechnology, Madurai Kamaraj University, Madurai, 625021 Tamil Nadu India
| | - Karuppannan Veluthambi
- Department of Plant Biotechnology, School of Biotechnology, Madurai Kamaraj University, Madurai, 625021 Tamil Nadu India
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Rajeswaran R, Golyaev V, Seguin J, Zvereva AS, Farinelli L, Pooggin MM. Interactions of Rice tungro bacilliform pararetrovirus and its protein P4 with plant RNA-silencing machinery. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:1370-8. [PMID: 25122481 DOI: 10.1094/mpmi-07-14-0201-r] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Small interfering RNA (siRNA)-directed gene silencing plays a major role in antiviral defense. Virus-derived siRNAs inhibit viral replication in infected cells and potentially move to neighboring cells, immunizing them from incoming virus. Viruses have evolved various ways to evade and suppress siRNA production or action. Here, we show that 21-, 22-, and 24-nucleotide (nt) viral siRNAs together constitute up to 19% of total small RNA population of Oryza sativa plants infected with Rice tungro bacilliform virus (RTBV) and cover both strands of the RTBV DNA genome. However, viral siRNA hotspots are restricted to a short noncoding region between transcription and reverse-transcription start sites. This region generates double-stranded RNA (dsRNA) precursors of siRNAs and, in pregenomic RNA, forms a stable secondary structure likely inaccessible to siRNA-directed cleavage. In transient assays, RTBV protein P4 suppressed cell-to-cell spread of silencing but enhanced cell-autonomous silencing, which correlated with reduced 21-nt siRNA levels and increased 22-nt siRNA levels. Our findings imply that RTBV generates decoy dsRNA that restricts siRNA production to the structured noncoding region and thereby protects other regions of the viral genome from repressive action of siRNAs, while the viral protein P4 interferes with cell-to-cell spread of antiviral silencing.
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Wang WC, Wu CY, Lai YC, Lin NS, Hsu YH, Hu CC. Characterization of the cryptic AV3 promoter of ageratum yellow vein virus in prokaryotic and eukaryotic systems. PLoS One 2014; 9:e108608. [PMID: 25268755 PMCID: PMC4182527 DOI: 10.1371/journal.pone.0108608] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 08/25/2014] [Indexed: 11/19/2022] Open
Abstract
A cryptic prokaryotic promoter, designated AV3 promoter, has been previously identified in certain begomovirus genus, including ageratum yellow vein virus isolate NT (AYVV-NT). In this study, we demonstrated that the core nucleotides in the putative -10 and -35 boxes are necessary but not sufficient for promoter activity in Escherichia coli, and showed that AYVV-NT AV3 promoter could specifically interact with single-stranded DNA-binding protein and sigma 70 of E. coli involved in transcription. Several AYVV-NT-encoded proteins were found to increase the activity of AV3 promoter. The transcription start sites downstream to AV3 promoter were mapped to nucleotide positions 803 or 805 in E. coli, and 856 in Nicotiana benthamiana. The eukaryotic activity of AV3 promoter and the translatability of a short downstream open reading frame were further confirmed by using a green fluorescent protein reporter construct in yeast (Saccharomyces cerevisiae) cells. These results suggested that AV3 promoter might be a remnant of evolution that retained cryptic activity at present.
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Affiliation(s)
- Wei-Chen Wang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Chia-Ying Wu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Yi-Chin Lai
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei, Taiwan
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Chung-Chi Hu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
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Ashraf MA, Shahid AA, Rao AQ, Bajwa KS, Husnain T. Functional characterization of a bidirectional plant promoter from cotton leaf curl Burewala virus using an Agrobacterium-mediated transient assay. Viruses 2014; 6:223-42. [PMID: 24424501 PMCID: PMC3917440 DOI: 10.3390/v6010223] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 12/14/2013] [Accepted: 12/24/2013] [Indexed: 11/16/2022] Open
Abstract
The C1 promoter expressing the AC1 gene, and V1 promoter expressing the AV1 gene are located in opposite orientations in the large intergenic region of the Cotton leaf curl Burewala virus (CLCuBuV) genome. Agro-infiltration was used to transiently express putative promoter constructs in Nicotiana tabacum and Gossypium hirsutum leaves, which was monitored by a GUS reporter gene, and revealed that the bidirectional promoter of CLCuBuV transcriptionally regulates both the AC1 and AV1 genes. The CLCuBuV C1 gene promoter showed a strong, consistent transient expression of the reporter gene (GUS) in N. tabacum and G. hirsutum leaves and exhibited GUS activity two- to three-fold higher than the CaMV 35S promoter. The CLCuBuV bidirectional gene promoter is a nearly constitutive promoter that contains basic conserved elements. Many cis-regulatory elements (CREs) were also analyzed within the bidirectional plant promoters of CLCuBuV and closely related geminiviruses, which may be helpful in understanding the transcriptional regulation of both the virus and host plant.
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Affiliation(s)
- Muhammad Aleem Ashraf
- Plant Biotechnology Laboratory, Centre of Excellence in Molecular Biology (CEMB), University of the Punjab, Lahore 53700, Pakistan.
| | - Ahmad Ali Shahid
- Plant Biotechnology Laboratory, Centre of Excellence in Molecular Biology (CEMB), University of the Punjab, Lahore 53700, Pakistan.
| | - Abdul Qayyum Rao
- Plant Biotechnology Laboratory, Centre of Excellence in Molecular Biology (CEMB), University of the Punjab, Lahore 53700, Pakistan.
| | - Kamran Shehzad Bajwa
- Plant Biotechnology Laboratory, Centre of Excellence in Molecular Biology (CEMB), University of the Punjab, Lahore 53700, Pakistan.
| | - Tayyab Husnain
- Plant Biotechnology Laboratory, Centre of Excellence in Molecular Biology (CEMB), University of the Punjab, Lahore 53700, Pakistan.
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Gazala IFS, Sahoo RN, Pandey R, Mandal B, Gupta VK, Singh R, Sinha P. Spectral reflectance pattern in soybean for assessing yellow mosaic disease. INDIAN JOURNAL OF VIROLOGY : AN OFFICIAL ORGAN OF INDIAN VIROLOGICAL SOCIETY 2013; 24:242-9. [PMID: 24426282 PMCID: PMC3784907 DOI: 10.1007/s13337-013-0161-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 08/19/2013] [Indexed: 11/25/2022]
Abstract
Remote sensing technique is useful for monitoring large crop area at a single time point, which is otherwise not possible by visual observation alone. Yellow mosaic disease (YMD) is a serious constraint in soybean production in India. However, hardly any basic information is available for monitoring YMD by remote sensing. Present study examines spectral reflectance of soybean leaves due to Mungbean yellow mosaic India virus (MYMIV) infection in order to identify YMD sensitive spectral ratio or reflectance. Spectral reflectance measurement indicated significant (p < 0.001) change in reflectance in the infected soybean canopy as compared to the healthy one. In the infected canopy, reflectance increased in visible region and decreased in near infra-red region of spectrum. Reflectance sensitivity analysis indicated wavelength ~642, ~686 and ~750 nm were sensitive to YMD infection. Whereas, in yellow leaves induced due to nitrogen deficiency, the sensitive wavelength was ~589 nm. Due to viral infection, a shift occurred in red and infra-red slope (called red edge) on the left in comparison to healthy one. Red edge shift was a good indicator to discriminate yellow mosaic as chlorophyll gets degraded due to MYMIV infection. Correlation of reflectance at 688 nm (R688) and spectral reflectance ratio at 750 and 445 nm (R750/R445) with the weighted mosaic index indicated that detection of yellow mosaic is possible based on these sensitive bands. Our study for the first time identifies the yellow mosaic sensitive band as R688 and R750/R445, which could be utilized to scan satellite data for monitoring YMD affected soybean cropping regions.
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Affiliation(s)
- I. F. Saad Gazala
- />Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi, 110012 India
| | - R. N. Sahoo
- />Division of Agricultural Physics, Indian Agricultural Research Institute, New Delhi, 110012 India
| | - Rakesh Pandey
- />Division of Plant Physiology, Indian Agricultural Research Institute, New Delhi, 110012 India
| | - Bikash Mandal
- />Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi, 110012 India
| | - V. K. Gupta
- />Division of Agricultural Physics, Indian Agricultural Research Institute, New Delhi, 110012 India
| | - Rajendra Singh
- />Phytotron Facility, Indian Agricultural Research Institute, New Delhi, 110012 India
| | - P. Sinha
- />Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi, 110012 India
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Abstract
Geminiviruses are a family of plant viruses that cause economically important plant diseases worldwide. These viruses have circular single-stranded DNA genomes and four to eight genes that are expressed from both strands of the double-stranded DNA replicative intermediate. The transcription of these genes occurs under the control of two bidirectional promoters and one monodirectional promoter. The viral proteins function to facilitate virus replication, virus movement, the assembly of virus-specific nucleoprotein particles, vector transmission and to counteract plant host defence responses. Recent research findings have provided new insights into the structure and function of these proteins and have identified numerous host interacting partners. Most of the viral proteins have been shown to be multifunctional, participating in multiple events during the infection cycle and have, indeed, evolved coordinated interactions with host proteins to ensure a successful infection. Here, an up-to-date review of viral protein structure and function is presented, and some areas requiring further research are identified.
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Affiliation(s)
- Vincent N Fondong
- Department of Biological Sciences, Delaware State University, 1200 North DuPont Highway, Dover, DE 19901, USA.
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44
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Wang WC, Hsu YH, Lin NS, Wu CY, Lai YC, Hu CC. A novel prokaryotic promoter identified in the genome of some monopartite begomoviruses. PLoS One 2013; 8:e70037. [PMID: 23936138 PMCID: PMC3723831 DOI: 10.1371/journal.pone.0070037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 06/14/2013] [Indexed: 01/08/2023] Open
Abstract
Geminiviruses are known to exhibit both prokaryotic and eukaryotic features in their genomes, with the ability to express their genes and even replicate in bacterial cells. We have demonstrated previously the existence of unit-length single-stranded circular DNAs of Ageratum yellow vein virus (AYVV, a species in the genus Begomovirus, family Geminiviridae) in Escherichia coli cells, which prompted our search for unknown prokaryotic functions in the begomovirus genomes. By using a promoter trapping strategy, we identified a novel prokaryotic promoter, designated AV3 promoter, in nts 762-831 of the AYVV genome. Activity assays revealed that the AV3 promoter is strong, unidirectional, and constitutive, with an endogenous downstream ribosome binding site and a translatable short open reading frame of eight amino acids. Sequence analyses suggested that the AV3 promoter might be a remnant of prokaryotic ancestors that could be related to certain promoters of bacteria from marine or freshwater environments. The discovery of the prokaryotic AV3 promoter provided further evidence for the prokaryotic origin in the evolutionary history of geminiviruses.
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Affiliation(s)
- Wei-Chen Wang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Chia-Ying Wu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Yi-Chin Lai
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Chung-Chi Hu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
- * E-mail:
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45
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Pooggin MM. How can plant DNA viruses evade siRNA-directed DNA methylation and silencing? Int J Mol Sci 2013; 14:15233-59. [PMID: 23887650 PMCID: PMC3759858 DOI: 10.3390/ijms140815233] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 07/01/2013] [Accepted: 07/01/2013] [Indexed: 11/16/2022] Open
Abstract
Plants infected with DNA viruses produce massive quantities of virus-derived, 24-nucleotide short interfering RNAs (siRNAs), which can potentially direct viral DNA methylation and transcriptional silencing. However, growing evidence indicates that the circular double-stranded DNA accumulating in the nucleus for Pol II-mediated transcription of viral genes is not methylated. Hence, DNA viruses most likely evade or suppress RNA-directed DNA methylation. This review describes the specialized mechanisms of replication and silencing evasion evolved by geminiviruses and pararetoviruses, which rescue viral DNA from repressive methylation and interfere with transcriptional and post-transcriptional silencing of viral genes.
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Affiliation(s)
- Mikhail M Pooggin
- University of Basel, Department of Environmental Sciences, Botany, Schönbeinstrasse 6, Basel 4056, Switzerland.
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46
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Berger MR, Sunter G. Identification of sequences required for AL2-mediated activation of the tomato golden mosaic virus-yellow vein BR1 promoter. J Gen Virol 2013; 94:1398-1406. [PMID: 23486662 DOI: 10.1099/vir.0.050161-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A 108 bp sequence has been identified in the tomato golden mosaic virus-yellow vein (yvTGMV) B component that is necessary and sufficient for AL2-mediated activation of the BR1 promoter. The sequence appears to have a bipartite arrangement, with elements located between -144 to -77 and -59 to -36 from the transcription start site, with both being required for activation by AL2. These sequences are located upstream of a TATA box and bind nuclear proteins from spinach, tomato and Arabidopsis. These sequences are also capable of binding Arabidopsis PPD2, which has been shown previously to interact with the yvTGMV coat protein (CP) promoter. We have identified two putative transcription factor-binding sites (CCAAT and GTGANTG10) that are conserved in sequences necessary for activation of the yvTGMV BR1, as well as the yvTGMV and cabbage leaf curl virus (CabLCV) CP promoters, which are all activated by AL2. The yvTGMV BR1 promoter exhibits AL2-independent expression in vascular tissue, similar to the yvTGMV, CabLCV and spinach curly top virus CP promoters. Together, this further confirms a common regulatory mechanism for AL2-mediated activation of bipartite begomovirus promoters.
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Affiliation(s)
- Mary R Berger
- Department of Biology, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA
| | - Garry Sunter
- Department of Biology, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA
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Vazquez F, Hohn T. Biogenesis and Biological Activity of Secondary siRNAs in Plants. SCIENTIFICA 2013; 2013:783253. [PMID: 24278785 PMCID: PMC3820352 DOI: 10.1155/2013/783253] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 12/06/2012] [Indexed: 05/25/2023]
Abstract
Two important hallmarks of RNA silencing in plants are (1) its ability to self-amplify by using a mechanism called transitivity and (2) its ability to spread locally and systemically through the entire plant. Crucial advances have been made in recent years in understanding the molecular mechanisms of these phenomena. We review here these recent findings, and we highlight the recently identified endogenous small RNAs that use these advantageous properties to act either as patterning signals in important developmental programs or as a part of regulatory cascades.
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Affiliation(s)
- Franck Vazquez
- Institute of Botany, University of Basel, Zürich-Basel Plant Science Center, Part of the Swiss Plant Science Web, CH-4056 Basel, Switzerland
| | - Thomas Hohn
- Institute of Botany, University of Basel, Zürich-Basel Plant Science Center, Part of the Swiss Plant Science Web, CH-4056 Basel, Switzerland
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48
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Akbar F, Briddon RW, Vazquez F, Saeed M. Transcript mapping of Cotton leaf curl Burewala virus and its cognate betasatellite, Cotton leaf curl Multan betasatellite. Virol J 2012; 9:249. [PMID: 23106938 PMCID: PMC3545858 DOI: 10.1186/1743-422x-9-249] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 10/25/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Whitefly-transmitted geminiviruses (family Geminiviridae, genus Begomovirus) are major limiting factors for the production of numerous dicotyledonous crops throughout the warmer regions of the world. In the Old World a small number of begomoviruses have genomes consisting of two components whereas the majority have single-component genomes. Most of the monopartite begomoviruses associate with satellite DNA molecules, the most important of which are the betasatellites. Cotton leaf curl disease (CLCuD) is one of the major problems for cotton production on the Indian sub-continent. Across Pakistan, CLCuD is currently associated with a single begomovirus (Cotton leaf curl Burewala virus [CLCuBuV]) and the cotton-specific betasatellite Cotton leaf curl Multan betasatellite (CLCuMuB), both of which have recombinant origins. Surprisingly, CLCuBuV lacks C2, one of the genes present in all previously characterized begomoviruses. Virus-specific transcripts have only been mapped for few begomoviruses, including one monopartite begomovirus that does not associate with betasatellites. Similarly, the transcripts of only two betasatellites have been mapped so far. The study described has investigated whether the recombination/mutation events involved in the evolution of CLCuBuV and its associated CLCuMuB have affected their transcription strategies. RESULTS The major transcripts of CLCuBuV and its associated betasatellite (CLCuMuB) from infected Nicotiana benthamiana plants have been determined. Two complementary-sense transcripts of ~1.7 and ~0.7 kb were identified for CLCuBuV. The ~1.7 kb transcript appears similar in position and size to that of several begomoviruses and likely directs the translation of C1 and C4 proteins. Both complementary-sense transcripts can potentially direct the translation of C2 and C3 proteins. A single virion-sense transcript of ~1 kb, suitable for translation of the V1 and V2 genes was identified. A predominant complementary-sense transcript was also confirmed for the betasatellite. CONCLUSIONS Overall, the transcription of CLCuBuV and the recombinant CLCuMuB is equivalent to earlier mapped begomoviruses/betasatellites. The recombination events that featured in the origins of these components had no detectable effects on transcription. The transcripts spanning the mutated C2 gene showed no evidence for involvement of splicing in restoring the ability to express intact C2 protein.
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Affiliation(s)
- Fazal Akbar
- Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan
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49
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Aregger M, Borah BK, Seguin J, Rajeswaran R, Gubaeva EG, Zvereva AS, Windels D, Vazquez F, Blevins T, Farinelli L, Pooggin MM. Primary and secondary siRNAs in geminivirus-induced gene silencing. PLoS Pathog 2012; 8:e1002941. [PMID: 23028332 PMCID: PMC3460622 DOI: 10.1371/journal.ppat.1002941] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Accepted: 08/18/2012] [Indexed: 11/20/2022] Open
Abstract
In plants, RNA silencing-based antiviral defense is mediated by Dicer-like (DCL) proteins producing short interfering (si)RNAs. In Arabidopsis infected with the bipartite circular DNA geminivirus Cabbage leaf curl virus (CaLCuV), four distinct DCLs produce 21, 22 and 24 nt viral siRNAs. Using deep sequencing and blot hybridization, we found that viral siRNAs of each size-class densely cover the entire viral genome sequences in both polarities, but highly abundant siRNAs correspond primarily to the leftward and rightward transcription units. Double-stranded RNA precursors of viral siRNAs can potentially be generated by host RDR-dependent RNA polymerase (RDR). However, genetic evidence revealed that CaLCuV siRNA biogenesis does not require RDR1, RDR2, or RDR6. By contrast, CaLCuV derivatives engineered to target 30 nt sequences of a GFP transgene by primary viral siRNAs trigger RDR6-dependent production of secondary siRNAs. Viral siRNAs targeting upstream of the GFP stop codon induce secondary siRNAs almost exclusively from sequences downstream of the target site. Conversely, viral siRNAs targeting the GFP 3′-untranslated region (UTR) induce secondary siRNAs mostly upstream of the target site. RDR6-dependent siRNA production is not necessary for robust GFP silencing, except when viral siRNAs targeted GFP 5′-UTR. Furthermore, viral siRNAs targeting the transgene enhancer region cause GFP silencing without secondary siRNA production. We conclude that the majority of viral siRNAs accumulating during geminiviral infection are RDR1/2/6-independent primary siRNAs. Double-stranded RNA precursors of these siRNAs are likely generated by bidirectional readthrough transcription of circular viral DNA by RNA polymerase II. Unlike transgenic mRNA, geminiviral mRNAs appear to be poor templates for RDR-dependent production of secondary siRNAs. RNA silencing directed by small RNAs (sRNAs) regulates gene expression and mediates defense against invasive nucleic acids such as transposons, transgenes and viruses. In plants and some animals, RNA-dependent RNA polymerase (RDR) generates precursors of secondary sRNAs that reinforce silencing. Most plant mRNAs silenced by miRNAs or primary siRNAs do not spawn secondary siRNAs, suggesting that they may have evolved to be poor templates for RDR. By contrast, silenced transgenes often produce RDR-dependent secondary siRNAs. Here we demonstrate that massive production of 21, 22 and 24 nt viral siRNAs in DNA geminivirus-infected Arabidopsis does not require the functional RDRs RDR1, RDR2, or RDR6. Deep sequencing analysis indicates that dsRNA precursors of these primary viral siRNAs are likely generated by RNA polymerase II-mediated bidirectional readthrough transcription on the circular viral DNA. Primary viral siRNAs engineered to target a GFP transgene trigger robust, RDR6-dependent production of secondary siRNAs, indicating that geminivirus infection does not suppress RDR6 activity. We conclude that geminiviral mRNAs, which can potentially be cleaved by primary viral siRNAs, are resistant to RDR-dependent amplification of secondary siRNAs. We speculate that, like most plant mRNAs, geminiviral mRNAs may have evolved to evade RDR activity.
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Affiliation(s)
- Michael Aregger
- Institute of Botany, University of Basel, Basel, Switzerland
| | | | - Jonathan Seguin
- Institute of Botany, University of Basel, Basel, Switzerland
- Fasteris SA, Plan-les-Ouates, Switzerland
| | | | | | - Anna S. Zvereva
- Institute of Botany, University of Basel, Basel, Switzerland
| | - David Windels
- Institute of Botany, University of Basel, Basel, Switzerland
| | - Franck Vazquez
- Institute of Botany, University of Basel, Basel, Switzerland
| | - Todd Blevins
- Biology Department, Indiana University, Bloomington, Indiana, United States of America
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Rahman J, Karjee S, Mukherjee SK. MYMIV-AC2, a geminiviral RNAi suppressor protein, has potential to increase the transgene expression. Appl Biochem Biotechnol 2012; 167:758-75. [PMID: 22592775 DOI: 10.1007/s12010-012-9702-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 04/23/2012] [Indexed: 10/28/2022]
Abstract
Gene silencing is one of the limiting factors for transgene expression in plants. But the plant viruses have learnt to suppress gene silencing by encoding the protein(s), called RNA silencing suppressor(s) (RSS). Hence, these proteins could be used to overcome the limitation for transgene expression. The RNAi suppressors, namely HC-Pro and P19, have been shown to enhance the transgene expression but other RSS proteins have not been screened for similar role. Moreover, none of RSSs from the DNA viruses are known for enhancing the expression of transgenes. The Mungbean Yellow Mosaic India Virus (MYMIV) belonging to the genus Begomovirus within the family of Geminiviridae encodes an RSS called the AC2 protein. Here, we used AC2 to elevate the expression of the transgenes. Upon introduction of MYMIV-AC2 in the silenced GFP transgenic tobacco lines, by either genetic hybridisation or transgenesis, the GFP expression was enhanced several fold in F1 and T0 lines. The GFP-siRNA levels were much reduced in F1 and T0 lines compared with those of the initial parental silenced lines. The enhanced GFP expression was also observed at the cellular level. This approach was also successful in enhancing the expression of another transgene, namely topoisomeraseII.
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Affiliation(s)
- Jamilur Rahman
- Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
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