Tobacco Mosaic Virus

Carr, John P.; Talbot, Nicholas J.

doi:10.1002/9781119312994.apr0102

Cited by 7 publications

(8 citation statements)

References 238 publications

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“…The viral strains used in this study were the common (U1) strain of TMV [ 58 ], and TMV.GFP (TMV30B.GFP constructed by Shivprasad et al [ 45 ]). Capped TMV.GFP infectious RNA was re-generated by in vitro transcription as previously described and inoculated onto 3- to 5-week old N. benthamiana plants to prepare aliquots of infectious sap as described by Murphy et al [ 46 ].…”

Section: Methodsmentioning

confidence: 99%

Salicylic acid treatment and expression of an RNA-dependent RNA polymerase 1 transgene inhibit lethal symptoms and meristem invasion during tobacco mosaic virus infection in Nicotiana benthamiana

Lee

Zheng

et al. 2016

BMC Plant Biol

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BackgroundHost RNA-dependent RNA polymerases (RDRs) 1 and 6 contribute to antiviral RNA silencing in plants. RDR6 is constitutively expressed and was previously shown to limit invasion of Nicotiana benthamiana meristem tissue by potato virus X and thereby inhibit disease development. RDR1 is inducible by salicylic acid (SA) and several other phytohormones. But although it contributes to basal resistance to tobacco mosaic virus (TMV) it is dispensable for SA-induced resistance in inoculated leaves. The laboratory accession of N. benthamiana is a natural rdr1 mutant and highly susceptible to TMV. However, TMV-induced symptoms are ameliorated in transgenic plants expressing Medicago truncatula RDR1.ResultsIn MtRDR1-transgenic N. benthamiana plants the spread of TMV expressing the green fluorescent protein (TMV.GFP) into upper, non-inoculated, leaves was not inhibited. However, in these plants exclusion of TMV.GFP from the apical meristem and adjacent stem tissue was greater than in control plants and this exclusion effect was enhanced by SA. TMV normally kills N. benthamiana plants but although MtRDR1-transgenic plants initially displayed virus-induced necrosis they subsequently recovered. Recovery from disease was markedly enhanced by SA treatment in MtRDR1-transgenic plants whereas in control plants SA delayed but did not prevent systemic necrosis and death. Following SA treatment of MtRDR1-transgenic plants, extractable RDR enzyme activity was increased and Western blot analysis of RDR extracts revealed a band cross-reacting with an antibody raised against MtRDR1. Expression of MtRDR1 in the transgenic N. benthamiana plants was driven by a constitutive 35S promoter derived from cauliflower mosaic virus, confirmed to be non-responsive to SA. This suggests that the effects of SA on MtRDR1 are exerted at a post-transcriptional level.ConclusionsMtRDR1 inhibits severe symptom development by limiting spread of virus into the growing tips of infected plants. Thus, RDR1 may act in a similar fashion to RDR6. MtRDR1 and SA acted additively to further promote recovery from disease symptoms in MtRDR1-transgenic plants. Thus it is possible that SA promotes MtRDR1 activity and/or stability through post-transcriptional effects.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0705-8) contains supplementary material, which is available to authorized users.

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Section: Methodsmentioning

confidence: 99%

Salicylic acid treatment and expression of an RNA-dependent RNA polymerase 1 transgene inhibit lethal symptoms and meristem invasion during tobacco mosaic virus infection in Nicotiana benthamiana

Lee

Zheng

et al. 2016

BMC Plant Biol

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“…The onset of infection involves dynamic interactions between the viral encoded RSS and HSM [3,14] or its proposed regulators [15]. Plants respond to perturbations of silencing machinery by deploying additional layers of defense measures to fight the invading viruses [15].…”

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confidence: 99%

Overexpression of an insect virus encoded silencing suppressor does not enhance plants’ susceptibility to its natural virus

et al. 2021

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RNA silencing plays a key role in shielding plant and animal hosts against viral invasion and infection. Viruses encode RNA silencing suppressors (RSS) to block small RNA guided silencing of viral transcripts. The B2 protein encoded by Flock House virus (FHV) is a wellcharacterized RSS that facilitates infection in insects. It has been shown to act as a functional RSS in plants. FHVB2 over-expressing tobacco plants were used to study the effect of RSS on plant susceptibility to Tobacco mosaic virus (TMV), its natural pathogen. The major symptoms observed in TMV-infected transgenic plants were greenish mosaic, puckering and distortion of leaves, but the infected transgenic leaves were able to resist chlorophyll loss. The infected leaves of transgenic plants showed no significant difference in accumulation of virus when compared with that of the wild type plants. FHVB2 plants showed higher levels of H 2 O 2 and the ROS scavenging enzymes, APX and SOD. This suggests that interference of FHVB2 with RNA silencing machinery may activate alternative defense pathways in the plants so that they are not overly sensitive to TMV infection.RNA silencing is an efficient and effective defense mechanism by which plants protect themselves against the invading viruses. The phenomenon is primarily mediated by small interfering RNAs (siRNAs) that act in a sequencespecific manner to target and degrade the viral transcripts. This also helps in developing memory for protection during reinfection by the same or closely related viruses [1]. In counter-defense, viruses have evolved to acquire RNA silencing suppressors (RSS) that are able to interfere with the different components of host silencing machinery (HSM) to enable replication, movement and disease development [2]. The RSS show huge diversity in their sequence, structure, function and mode of action [3]. The mechanism of action of viral RSS is complex and not fully understood. Most RSS can suppress silencing in both animal and plant cells, regardless of their host preference due to conserved nature of the HSM.Flock House virus (FHV) belonging to the genus Alphanodavirus, family Nodaviridae encodes protein B2 that acts as a potent RSS and facilitates viral infection in insects. The B2 protein contains 106 residues and is translated from sub-genomic RNA-3 region [4], which corresponds to ORF1b located at the 3 0 end of its singlestranded RNA genome. FHVB2 shares functional similarity with 2b of cucumber mosaic virus (CMV) [5] and acts

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“…The 30-kDa MP is formed at early stage of infection. TMV can potentially encode two more proteins (Carr, 2004). One is a 54-kDa protein; its ORF is contained in the third subgenomic RNA called I 1 .…”

Section: Viral Genesmentioning

confidence: 99%

Positive-Sense Viral RNA

Multiplication of RNA Plant Viruses

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Tobacco Mosaic Virus

Abstract: The sections in this article areIntroductionTobacco Mosaic Virus: Virion and Genome StructureTMVReplication and the Synthesis of SubgenomicmRNAsMovement ofTMVwithin the HostHost Reactions toTMVFuture Directions forTMVResearch: Making an Old Foe into a New Friend?Acknowledgments

Cited by 7 publications

References 238 publications

Salicylic acid treatment and expression of an RNA-dependent RNA polymerase 1 transgene inhibit lethal symptoms and meristem invasion during tobacco mosaic virus infection in Nicotiana benthamiana

Salicylic acid treatment and expression of an RNA-dependent RNA polymerase 1 transgene inhibit lethal symptoms and meristem invasion during tobacco mosaic virus infection in Nicotiana benthamiana

Overexpression of an insect virus encoded silencing suppressor does not enhance plants’ susceptibility to its natural virus

Positive-Sense Viral RNA

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