Hibiscus chlorotic ringspot virus coat protein inhibits trans-acting small interfering RNA biogenesis in Arabidopsis

Many plant and animal viruses have evolved suppressor proteins to block host RNA silencing at various stages of the RNA silencing pathways. Hibiscus chlorotic ringspot virus (HCRSV) coat protein (CP) is capable of suppressing the transiently expressed sense-RNA-induced post-transcriptional gene silencing (PTGS) in Nicotiana benthamiana. Here, constitutively expressed HCRSV CP from transgenic Arabidopsis was found to be able to rescue expression of the silenced GUS transgene. The HCRSV CP-transgenic Arabidopsis (line CP6) displayed several developmental abnormalities: elongated, downwardly curled leaves and a lack of coordination between stamen and carpel, resulting in reduced seed set. These abnormalities are similar to those observed in mutations of the genes of Arabidopsis RNA-dependent polymerase 6 (rdr6), suppressor of gene silencing 3 (sgs3), ZIPPY (zip) and dicer-like 4 (dcl4). The accumulation of microRNA (miRNA) miR173 remained stable; however, the downstream trans-acting small interfering RNA (ta-siRNA) siR255 was greatly reduced. Real-time PCR analysis showed that expression of the ta-siRNA-targeted At4g29770, At5g18040, PPR and ARF3 genes increased significantly, especially in the inflorescences. Genetic crossing of CP6 with an amplicon-silenced line (containing a potato virus X–green fluorescent protein transgene under the control of the 35S cauliflower mosaic virus promoter) suggested that HCRSV CP probably interfered with gene silencing at a step after RDR6. The reduced accumulation of ta-siRNA might result from the interference of HCRSV CP with Dicer-like protein(s), responsible for the generation of dsRNA in ta-siRNA biogenesis.

Download Full-text

Small Interfering RNA-Induced Transcriptional Gene Silencing in Human Cells

Science ◽

10.1126/science.1101372 ◽

2004 ◽

Vol 305 (5688) ◽

pp. 1289-1292 ◽

Cited By ~ 613

Author(s):

K. V. Morris

Keyword(s):

Gene Silencing ◽

Small Interfering Rna ◽

Human Cells ◽

Transcriptional Gene Silencing ◽

Interfering Rna

Download Full-text

Faculty Opinions recommendation of Small interfering RNA-induced transcriptional gene silencing in human cells.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1020984.254622 ◽

2004 ◽

Author(s):

Andrew D Sharrocks

Keyword(s):

Gene Silencing ◽

Small Interfering Rna ◽

Human Cells ◽

Transcriptional Gene Silencing ◽

Interfering Rna

Download Full-text

Faculty Opinions recommendation of Small interfering RNA-induced transcriptional gene silencing in human cells.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1020984.240592 ◽

2004 ◽

Author(s):

Giovanni Neri

Keyword(s):

Gene Silencing ◽

Small Interfering Rna ◽

Human Cells ◽

Transcriptional Gene Silencing ◽

Interfering Rna

Download Full-text

Tomato ringspot virus Coat Protein Binds to ARGONAUTE 1 and Suppresses the Translation Repression of a Reporter Gene

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-04-14-0099-r ◽

2014 ◽

Vol 27 (9) ◽

pp. 933-943 ◽

Cited By ~ 36

Author(s):

Rajita A. Karran ◽

Hélène Sanfaçon

Keyword(s):

Coat Protein ◽

Reporter Gene ◽

Rna Silencing ◽

Fluorescent Protein ◽

Plant Viruses ◽

Ringspot Virus ◽

Small Interfering Rnas ◽

Gfp Expression ◽

Translation Repression ◽

Tomato Ringspot Virus

RNA silencing regulates plant gene expression and antiviral defenses and functions by cleaving target RNAs or repressing translation. As a counter defense, many plant viruses encode suppressor proteins that sequester small RNAs or inactivate Argonaute (AGO) proteins. All known plant virus silencing suppressor activities eventually inhibit the degradation of target mRNAs. Using a transiently expressed green fluorescent protein (GFP) reporter gene, we show that Tomato ringspot virus (ToRSV) coat protein (CP) is a suppressor of RNA silencing that enhances GFP expression but does not prevent the degradation of the GFP mRNA or the accumulation of GFP small interfering RNAs (siRNAs). Coexpression of the CP with GFP resulted in increased association of residual GFP mRNAs with polysome fractions and reduced association of GFP siRNAs with monosome fractions. AGO1 was co-immunoprecipitated with the CP and CP expression destabilized AGO1. A WG motif within the CP was critical for the enhanced GFP expression, AGO1 interaction, and AGO1 destabilization, suggesting that the ToRSV CP acts as an AGO-hook protein and competes for AGO binding with a plant cellular GW/WG protein involved in translation repression.

Download Full-text

Aberrant promoter methylation occurred from multicopy transgene and SU(VAR)3 - 9 homolog 9 (SUVH9) gene in transgenic Nicotiana benthamiana

Functional Plant Biology ◽

10.1071/fp12051 ◽

2012 ◽

Vol 39 (9) ◽

pp. 764 ◽

Cited By ~ 6

Author(s):

Gi-Ho Lee ◽

Seong-Han Sohn ◽

Eun-Young Park ◽

Young-Doo Park

Keyword(s):

Gene Silencing ◽

Nicotiana Benthamiana ◽

Fluorescent Protein ◽

Cauliflower Mosaic Virus ◽

Camv 35S Promoter ◽

35S Promoter ◽

Camv 35S ◽

Histone Deacetylase 1 ◽

Transgenic Lines ◽

Green Fluorescent

The chemical modification of DNA by methylation is a heritable trait and can be subsequently reversed without altering the original DNA sequence. Methylation can reduce or silence gene expression and is a component of a host’s defence response to foreign nucleic acids. In our study, we employed a plant transformation strategy using Nicotiana benthamiana Domin to study the heritable stability of the introduced transgenes. Through the introduction of the cauliflower mosaic virus (CaMV) 35S promoter and the green fluorescent protein (GFP) reporter gene, we demonstrated that this introduced promoter often triggers a homology-dependent gene-silencing (HDGS) response. These spontaneous transgene-silencing phenomena are due to methylation of the CaMV 35S promoter CAAT box during transgenic plant growth. This process is catalysed by SU(VAR)3–9 homologue 9 (SUVH9), histone deacetylase 1 (HDA1) and domains rearranged methylase 2 (DRM2). In particular, we showed from our data that SUVH9 is the key regulator of methylation activity in epigenetically silenced GFP transgenic lines; therefore, our findings demonstrate that an introduced viral promoter and transgene can be subject to a homology-dependent gene-silencing mechanism that can downregulate its expression and negatively influence the heritable stability of the transgene.

Download Full-text

Targeted Gene Silencing by Small Interfering RNA-Based Knock-Down Technology

Current Pharmaceutical Biotechnology ◽

10.2174/1389201043489558 ◽

2004 ◽

Vol 5 (1) ◽

pp. 1-7 ◽

Cited By ~ 19

Author(s):

Bentham Science Publisher Zhang J. ◽

Bentham Science Publisher Hua Z.C.

Keyword(s):

Gene Silencing ◽

Small Interfering Rna ◽

Knock Down ◽

Interfering Rna

Download Full-text

Cymbidium Ringspot Virus Harnesses RNA Silencing To Control the Accumulation of Virus Parasite Satellite RNA

Journal of Virology ◽

10.1128/jvi.01343-08 ◽

2008 ◽

Vol 82 (23) ◽

pp. 11851-11858 ◽

Cited By ~ 19

Author(s):

Vitantonio Pantaleo ◽

József Burgyán

Keyword(s):

Rna Silencing ◽

Sequence Similarity ◽

Helper Virus ◽

Ringspot Virus ◽

Silencing Suppressor ◽

Short Interfering Rna ◽

Satellite Rna ◽

The Cost ◽

Interfering Rna ◽

Rna Replicon

ABSTRACT Cymbidium ringspot virus (CymRSV) satellite RNA (satRNA) is a parasitic subviral RNA replicon that replicates and accumulates at the cost of its helper virus. This 621-nucleotide (nt) satRNA species has no sequence similarity to the helper virus, except for a 51-nt-long region termed the helper-satellite homology (HSH) region, which is essential for satRNA replication. We show that the accumulation of satRNA strongly depends on temperature and on the presence of the helper virus p19 silencing suppressor protein, suggesting that RNA silencing plays a crucial role in satRNA accumulation. We also demonstrate that another member of the Tombusvirus genus, Carnation Italian ringspot virus (CIRV), supports satRNA accumulation at a higher level than CymRSV. Our results suggest that short interfering RNA (siRNA) derived from CymRSV targets satRNA more efficiently than siRNA from CIRV, possibly because of the higher sequence similarity between the HSH regions of the helper and CIRV satRNAs. RNA silencing sensor RNA carrying the putative satRNA target site in the HSH region was efficiently cleaved when transiently expressed in CymRSV-infected plants but not in CIRV-infected plants. Strikingly, replacing the CymRSV HSH box2 sequence with that of CIRV restores satRNA accumulation both at 24°C and in the absence of the p19 suppressor protein. These findings demonstrate the extraordinary adaptation of this virus to its host in terms of harnessing the antiviral silencing response of the plant to control the virus parasite satRNA.

Download Full-text