Reprogramming of RNA silencing triggered by cucumber mosaic virus infection in Arabidopsis

Abstract Background RNA silencing has an important role mediating sequence-specific virus resistance in plants. The complex interaction of viruses with RNA silencing involves the loading of viral small interfering RNAs (vsiRNAs) into its host ARGONAUTE (AGO) proteins. As a side effect of their antiviral activity, vsiRNAs loading into AGO proteins can also mediate the silencing of endogenous genes. Here, we analyze at the genome-wide level both aspects of the interference of cucumber mosaic virus (CMV) with the RNA silencing machinery of Arabidopsis thaliana. Results We observe CMV-derived vsiRNAs affect the levels of endogenous sRNA classes. Furthermore, we analyze the incorporation of vsiRNAs into AGO proteins with a described antiviral role and the viral suppressor of RNA silencing (VSR) 2b, by combining protein immunoprecipitation with sRNA high-throughput sequencing. Interestingly, vsiRNAs represent a substantial percentage of AGO-loaded sRNAs and displace other endogenous sRNAs. As a countermeasure, the VSR 2b loaded vsiRNAs and mRNA-derived siRNAs, which affect the expression of the genes they derive from. Additionally, we analyze how vsiRNAs incorporate into the endogenous RNA silencing pathways by exploring their target mRNAs using parallel analysis of RNA end (PARE) sequencing, which allow us to identify vsiRNA-targeted genes genome-wide. Conclusions This work exemplifies the complex relationship of RNA viruses with the endogenous RNA silencing machinery and the multiple aspects of virus resistance and virulence that this interaction induces.

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The Suppressor of Transgene RNA Silencing Encoded by Cucumber mosaic virus Interferes with Salicylic Acid-Mediated Virus Resistance

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.2001.14.6.715 ◽

2001 ◽

Vol 14 (6) ◽

pp. 715-724 ◽

Cited By ~ 158

Author(s):

Liang-Hui Ji ◽

Shou-Wei Ding

Keyword(s):

Salicylic Acid ◽

Cucumber Mosaic Virus ◽

Mosaic Virus ◽

Virus Resistance ◽

Rna Silencing ◽

Defense Mechanism ◽

Antiviral Defense ◽

Oxidase Gene ◽

Systemic Spread ◽

Systemic Infections

The Cucumber mosaic virus (CMV)-encoded 2b protein (Cmv2b) is a nuclear protein that suppresses transgene RNA silencing in Nicotiana benthamiana. Cmv2b is an important virulence determinant but nonessential for systemic spread in N. glutinosa, in contrast to its indispensable role for systemic infections in cucumber. Here, we report that Cmv2b became essential for systemic infections in older N. glutinosa plants or in young seedlings pre-treated with salicylic acid (SA). Expression of Cmv2b from the genome of either CMV or Tobacco mosaic virus significantly reduced the inhibitory effect of SA on virus accumulation in inoculated leaves and systemic leaves. A close correlation is demonstrated between Cmv2b expression and a reduced SA-dependent induction of the alternative oxidase gene, a component of the recently proposed SA-regulated antiviral defense. These results collectively reveal a novel activity of Cmv2b in the inhibition of SA-mediated virus resistance. We used a N. tabacum line expressing a bacterial nahG transgene that degrades SA to provide evidence for a Cmv2b-sensitive antiviral defense mechanism in tobacco in which SA acts as a positive modifier but not as an essential component. We propose that SA induces virus resistance by potentiating a RNA-silencing antiviral defense that is targeted by Cmv2b.

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Effects of the 2b Protein of Cucumber mosaic virus Subgroup IB Strain IA on Different Transgene-Induced RNA Silencing Pathways

Plant Molecular Biology Reporter ◽

10.1007/s11105-016-1020-0 ◽

2017 ◽

Vol 35 (2) ◽

pp. 265-272 ◽

Cited By ~ 4

Author(s):

Mayuko Koizumi ◽

Yumi Shimotori ◽

Yuta Saeki ◽

Sayaka Hirai ◽

Shin-ichiro Oka ◽

...

Keyword(s):

Cucumber Mosaic Virus ◽

Mosaic Virus ◽

Rna Silencing ◽

2B Protein ◽

Silencing Pathways

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Cucumber mosaic virus 2b protein inhibits RNA silencing pathways in green alga Chlamydomonas reinhardtii

Plant Cell Reports ◽

10.1007/s00299-010-0882-0 ◽

2010 ◽

Vol 29 (9) ◽

pp. 967-975 ◽

Cited By ~ 8

Author(s):

Joon-Woo Ahn ◽

Chun-Ji Yin ◽

Jang Ryol Liu ◽

Won-Joong Jeong

Keyword(s):

Chlamydomonas Reinhardtii ◽

Cucumber Mosaic Virus ◽

Mosaic Virus ◽

Green Alga ◽

Rna Silencing ◽

2B Protein ◽

Silencing Pathways

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Analysis of Mechanisms Involved in the Cucumber mosaic virus Satellite RNA-mediated Transgenic Resistance in Tomato Plants

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.2004.17.1.98 ◽

2004 ◽

Vol 17 (1) ◽

pp. 98-108 ◽

Cited By ~ 29

Author(s):

Fabrizio Cillo ◽

Mariella M. Finetti-Sialer ◽

Maria A. Papanice ◽

Donato Gallitelli

Keyword(s):

Cucumber Mosaic Virus ◽

Mosaic Virus ◽

Rna Silencing ◽

Resistance Mechanism ◽

Degradation Process ◽

Transgenic Tomato ◽

Satellite Rna ◽

Total Recovery ◽

Tomato Plants ◽

Free Strain

Transgenic tomato (Lycopersicon esculentum Mill. cv. UC82) plants expressing a benign variant of Cucumber mosaic virus satellite RNA (CMV Tfn-satRNA) were generated. The transformed plants did not produce symptoms when challenged with a satRNA-free strain of CMV (CMV-FL). The same plant lines initially were susceptible to necrosis elicited by a CMV strain supporting a necrogenic variant of satRNA (CMV-77), but a phenotype of total recovery from the necrosis was observed in the newly developing leaves. The features of the observed resistance were analyzed and are consistent with two different mechanisms of resistance. In transgenic plants inoculated with CMV-FL strain, the symptomless phenotype was correlated to the down-regulation of CMV by Tfn-satRNA, amplified from the transgene transcripts, as the first resistance mechanism. On the other hand, the delayed resistance to CMV-77 in transgenic tomato lines was mediated by a degradation process that targets satRNAs in a sequence-specific manner. Evidence is provided for a correlation between a reduced accumulation level of transgenic messenger Tfn-satRNA, the accumulation of small (approximately 23 nucleotides) RNAs with sequence homology to satRNAs, the progressively reduced accumulation of 77-satRNA in infected tissues, and the transition in infected plants from diseased to healthy. Thus, events leading to the degradation of satRNA sequences indicate a role for RNA silencing as the second mechanism determining resistance of transgenic tomato lines.

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Rice Stripe Mosaic Virus–Encoded P4 Is a Weak Suppressor of Viral RNA Silencing and Is Required for Disease Symptom Development

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-08-19-0239-ia ◽

2020 ◽

Vol 33 (3) ◽

pp. 412-422

Author(s):

Chao Zhang ◽

Dong Chen ◽

Guoyi Yang ◽

Xiyuan Yu ◽

Jianguo Wu

Keyword(s):

Mosaic Virus ◽

Rna Silencing ◽

Matrix Protein ◽

Expression System ◽

Potato Virus X ◽

Bimolecular Fluorescence Complementation ◽

Developmental Defects ◽

The Matrix ◽

Silencing Pathways ◽

Viral Suppressors

Viral suppressors of RNA silencing (VSRs) are a cluster of viral proteins that have evolved to counteract eukaryotic antiviral RNA silencing pathways, thereby contributing to viral pathogenicity. In this study, we revealed that the matrix protein P4 encoded by rice stripe mosaic virus (RSMV), which is an emerging cytoplasmic rhabdovirus, is a weak RNA silencing suppressor. By conducting yeast two-hybrid, bimolecular fluorescence complementation, and subcellular colocalization assays, we proved that P4 interacts with the rice endogenous suppressor of gene silencing 3 (OsSGS3). We also determined that P4 overexpression has no effect on OsSGS3 transcription. However, P4 can promote the degradation of OsSGS3 via ubiquitination and autophagy. Additionally, a potato virus X–based expression system was used to confirm that P4 enhances the development of mosaic symptoms on Nicotiana benthamiana leaves by promoting hydrogen peroxide accumulation but not cell death. To verify whether P4 is a pathogenicity factor in host plants, we generated transgenic P4-overexpressing rice plants that exhibited disease-related developmental defects including decreased plant height and excessive tillering. Our data suggest that RSMV-encoded P4 serves as a weak VSR that inhibits antiviral RNA silencing by targeting OsSGS3.

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Genetic Analyses of the FRNK Motif Function of Turnip mosaic virus Uncover Multiple and Potentially Interactive Pathways of Cross-Protection

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-04-14-0116-r ◽

2014 ◽

Vol 27 (9) ◽

pp. 944-955 ◽

Cited By ~ 21

Author(s):

Yi-Jung Kung ◽

Pin-Chun Lin ◽

Shyi-Dong Yeh ◽

Syuan-Fei Hong ◽

Nam-Hai Chua ◽

...

Keyword(s):

Innate Immunity ◽

Mosaic Virus ◽

Rna Silencing ◽

Turnip Mosaic Virus ◽

Cross Protection ◽

Mild Strain ◽

Silencing Suppression ◽

Helper Component Proteinase ◽

Silencing Pathways ◽

Protection Against Infection

Cross-protection triggered by a mild strain of virus acts as a prophylaxis to prevent subsequent infections by related viruses in plants; however, the underling mechanisms are not fully understood. Through mutagenesis, we isolated a mutant strain of Turnip mosaic virus (TuMV), named Tu-GK, that contains an Arg182Lys substitution in helper component-proteinase (HC-ProK) that confers complete cross-protection against infection by a severe strain of TuMV in Nicotiana benthamiana, Arabidopsis thaliana Col-0, and the Arabidopsis dcl2-4/dcl4-1 double mutant defective in DICER-like ribonuclease (DCL)2/DCL4-mediated silencing. Our analyses showed that HC-ProK loses the ability to interfere with microRNA pathways, although it retains a partial capability for RNA silencing suppression triggered by DCL. We further showed that Tu-GK infection triggers strong salicylic acid (SA)-dependent and SA-independent innate immunity responses. Our data suggest that DCL2/4-dependent and –independent RNA silencing pathways are involved, and may crosstalk with basal innate immunity pathways, in host defense and in cross-protection.

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