scholarly journals Replicase-Derived Resistance Against Pea early browning virus in Nicotiana benthamiana Is an Unstable Resistance Based upon Posttranscriptional Gene Silencing

2001 ◽  
Vol 14 (2) ◽  
pp. 196-203 ◽  
Author(s):  
Tom van den Boogaart ◽  
Fuijang Wen ◽  
Jeffrey W. Davies ◽  
George P. Lomonossoff
Keyword(s):  
Steady State ◽  
Gene Silencing ◽  
Virus Resistance ◽  
Nicotiana Benthamiana ◽  
Potato Virus X ◽  
Replicase Gene ◽  
Heterozygous Condition ◽  
Transcript Levels ◽  
Posttranscriptional Gene Silencing ◽  
Homozygous Condition

Virus resistance in Nicotiana benthamiana plants containing a translatable Pea early browning virus (PEBV) 54K sequence from the 201K replicase gene has been reported previously. Resistant plants contain multiple transgene copies divided between two loci. Analysis of a genetic series containing the two loci in separate homozygous or heterozygous condition suggest that only one of the loci is necessary to induce the resistance. The resistance observed in R2 and R3 generations of lines containing both transgene loci in homozygous condition became less consistent in R4 and R5 generations. This inversely correlated with steady-state transgene transcript levels of the segregating populations. The use of recombinant Potato virus X vectors carrying PEBV 54K sequences showed that the resistance is based upon posttranscriptional gene silencing, is non-strand specific, and recognizes 3′ located sequences within the PEBV 54K sequence.

scholarly journals In Situ Characterization of Cymbidium Ringspot Tombusvirus Infection-Induced Posttranscriptional Gene Silencing in Nicotiana benthamiana

2003 ◽  
Vol 77 (10) ◽  
pp. 6082-6086 ◽  
Author(s):  
Zoltán Havelda ◽  
Csaba Hornyik ◽  
Aniello Crescenzi ◽  
József Burgyán
Keyword(s):  
Viral Infection ◽  
Gene Silencing ◽  
Nicotiana Benthamiana ◽  
Defense Mechanism ◽  
Vascular Bundles ◽  
Wild Type ◽  
Posttranscriptional Gene Silencing ◽  
Defective Mutant ◽  
Ptgs Suppressor

ABSTRACT In plants, posttranscriptional gene silencing (PTGS) is an ancient and effective defense mechanism against viral infection. A number of viruses encode proteins that suppress virus-activated PTGS. The p19 protein of tombusviruses is a potent PTGS suppressor which interferes with the onset of PTGS-generated systemic signaling and is not required for viral replication or for viral movement in Nicotiana benthamiana. This unique feature of p19 suppressor allowed us to analyze the mechanism of PTGS-based host defense and its viral suppression without interfering with other viral functions. In contrast to the necrotic symptoms caused by wild-type tombusvirus, the infection of p19-defective mutant virus results in the development of a typical PTGS-associated recovery phenotype in N. benthamiana. In this report we show the effect of PTGS on the viral infection process for N. benthamiana infected with either wild-type Cymbidium Ringspot Tombusvirus (CymRSV) or a p19-defective mutant (Cym19stop). In situ analyses of different virus-derived products revealed that PTGS is not able to reduce accumulation of virus in primary infected cells regardless of the presence of p19 PTGS suppressor. We also showed that both CymRSV and Cym19stop viruses move systemically in the vasculature, with similar efficiencies. However, in contrast to the uniform accumulation of CymRSV throughout systemically infected leaves, the presence of Cym19stop virus was confined to and around the vascular bundles. These results suggest that the role of p19 is to prevent the onset of mobile signal-induced systemic PTGS ahead of the viral infection front, leading to generalized infection.

scholarly journals Arabidopsis SGS2 and SGS3 Genes Are Required for Posttranscriptional Gene Silencing and Natural Virus Resistance

Cell ◽  
2000 ◽  
Vol 101 (5) ◽  
pp. 533-542 ◽  
Author(s):  
Philippe Mourrain ◽  
Christophe Béclin ◽  
Taline Elmayan ◽  
Frank Feuerbach ◽  
Christian Godon ◽  
...  
Keyword(s):  
Gene Silencing ◽  
Virus Resistance ◽  
Posttranscriptional Gene Silencing ◽  
Natural Virus

scholarly journals The Occurrence of CMV-Specific Short RNAs in Transgenic Tobacco Expressing Virus-Derived Double-Stranded RNA is Indicative of Resistance to the Virus

2002 ◽  
Vol 15 (8) ◽  
pp. 826-833 ◽  
Author(s):  
Kriton Kalantidis ◽  
Stavros Psaradakis ◽  
Martin Tabler ◽  
Mina Tsagris
Keyword(s):  
Transgenic Plants ◽  
Gene Silencing ◽  
Transgenic Tobacco ◽  
Virus Resistance ◽  
Northern Analysis ◽  
Specific Gene ◽  
Posttranscriptional Gene Silencing ◽  
Short Rnas ◽  
Transgenic Lines ◽  
Viral Sequences

Expression or introduction of double-stranded (ds)RNA in eukaryotic cells can trigger sequence-specific gene silencing of transgenes, endogenes, and viruses. Transgenic plants producing dsRNAs with homology to viral sequences are likely to exhibit pathogen-derived resistance to the virus. Cucumber mosaic virus (CMV), a very widespread virus with over 1,000 host species, has the natural ability to suppress silencing in order to establish infection. Here, we report the generation of transgenic tobacco lines, where a DNA transgene containing an inverted repeat of CMV cDNA had been introduced. Expression of this DNA construct delivered an RNA transcript that is able to form an intramolecular double strand. Transgenic plants were challenged with CMV. Three categories of plants could be discriminated: susceptible plants, which typically reacted with milder symptoms than the wild-type control; a “recovery” phenotype, in which newly emerging leaves were free of symptoms; and plants that showed complete resistance. Northern analysis showed that the expression of CMV dsRNA caused, in some transgenic lines, the generation of short RNAs characteristic of posttranscriptional gene silencing. Those lines were CMV resistant. The correlation between the detection of short RNAs and virus resistance provides a molecular marker that makes it possible to predict success in attempts to engineer virus resistance by dsRNA.

Post-transcriptional gene silencing and virus resistance in Nicotiana benthamiana expressing a Grapevine virus A minireplicon

2008 ◽  
Vol 18 (3) ◽  
pp. 331-345 ◽  
Author(s):  
Marina Brumin ◽  
Svetlana Stukalov ◽  
Sabrina Haviv ◽  
Mookkan Muruganantham ◽  
Yoni Moskovitz ◽  
...  
Keyword(s):  
Gene Silencing ◽  
Virus Resistance ◽  
Nicotiana Benthamiana ◽  
Transcriptional Gene Silencing ◽  
Grapevine Virus ◽  
Grapevine Virus A ◽  
Post Transcriptional Gene Silencing

scholarly journals Tomato Mosaic Virus Replication Protein Suppresses Virus-Targeted Posttranscriptional Gene Silencing

2003 ◽  
Vol 77 (20) ◽  
pp. 11016-11026 ◽  
Author(s):  
Kenji Kubota ◽  
Shinya Tsuda ◽  
Atsushi Tamai ◽  
Tetsuo Meshi
Keyword(s):  
Gene Silencing ◽  
Mosaic Virus ◽  
Rna Degradation ◽  
Plant Viruses ◽  
Replication Protein ◽  
Tomato Mosaic Virus ◽  
Replicase Gene ◽  
Posttranscriptional Gene Silencing ◽  
Recombinant Viruses ◽  
Ptgs Suppressor

ABSTRACT Posttranscriptional gene silencing (PTGS), a homology-dependent RNA degradation system, has a role in defending against virus infection in plants, but plant viruses encode a suppressor to combat PTGS. Using transgenic tobacco in which the expression of green fluorescent protein (GFP) is posttranscriptionally silenced, we investigated a tomato mosaic virus (ToMV)-encoded PTGS suppressor. Infection with wild-type ToMV (L strain) interrupted GFP silencing in tobacco, coincident with visible symptoms, whereas some attenuated strains of ToMV (L11 and L11A strains) failed to suppress GFP silencing. Analyses of recombinant viruses containing the L and L11A strains revealed that a single base change in the replicase gene, which causes an amino acid substitution, is responsible for the symptomless and suppressor-defective phenotypes of the attenuated strains. An agroinfiltration assay indicated that the 130K replication protein acts as a PTGS suppressor. Small interfering RNAs (siRNAs) of 21 to 25 nucleotides accumulated during ToMV infection, suggesting that the major target of the ToMV-encoded suppressor is downstream from the production of siRNAs in the PTGS pathway. Analysis with GFP-tagged recombinant viruses revealed that the suppressor inhibits the establishment of the ToMV-targeted PTGS system in the inoculated leaves but does not detectably suppress the activity of the preexisting, sequence-specific PTGS machinery there. Taken together, these results indicate that it is likely that the ToMV-encoded suppressor, the 130K replication protein, blocks the utilization of silencing-associated small RNAs, so that a homology-dependent RNA degradation machinery is not newly formed.

scholarly journals Posttranscriptional Gene Silencing Does Not Play a Significant Role in Potato virus X Coat Protein-Mediated Resistance

2006 ◽  
Vol 96 (11) ◽  
pp. 1175-1178 ◽  
Author(s):  
A. A. Bazzini ◽  
H. E. Hopp ◽  
R. N. Beachy ◽  
S. Asurmendi
Keyword(s):  
Coat Protein ◽  
Gene Silencing ◽  
Significant Role ◽  
Potato Virus ◽  
Low Temperatures ◽  
Potato Virus X ◽  
Tobacco Plants ◽  
Posttranscriptional Gene Silencing ◽  
Coat Protein Mediated Resistance ◽  
High Level

The expression of a gene that encodes coat protein (CP) of Potato virus X (PVX) in transgenic tobacco plants confers a high level of CP-mediated rresistance (CP-MR) against PVX infection. To determine if posttranscriptional gene silencing (PTGS) plays a role in resistance, transgenic plants expressing PVX CP were challenged against PVX under conditions in which PTGS was suppressed by low temperatures or using viruses carrying PTGS suppressors. The data demonstrate that PTGS does not play a significant role in PVX CP-MR.

scholarly journals Contribution of the Zinc Finger to Zinc and DNA Binding by a Suppressor of Posttranscriptional Gene Silencing

2003 ◽  
Vol 77 (1) ◽  
pp. 696-700 ◽  
Author(s):  
Rene van Wezel ◽  
Huanting Liu ◽  
Zirong Wu ◽  
John Stanley ◽  
Yiguo Hong
Keyword(s):  
Dna Binding ◽  
Gene Silencing ◽  
Zinc Finger ◽  
Fluorescent Protein ◽  
Binding Capacity ◽  
Potato Virus X ◽  
Cysteine Residue ◽  
Binding Activity ◽  
Posttranscriptional Gene Silencing ◽  
Dna Binding Activity

ABSTRACT The zinc finger C36-X1-C38-X7-C46-X6-H53 of the nuclearly localized C2 protein of Tomato yellow leaf curl virus China is involved in pathogenicity and suppression of posttranscriptional gene silencing (PTGS). Here, we demonstrate that the zinc finger is indispensable for the C2 protein to bind zinc and DNA. Mutation of cysteine residue C36, C38, or C46 reduced the zinc and DNA binding capacity of C2 protein. When expressed from potato virus X, all three mutants, C2-C36R, C2-C38N, and C2-C46I, tagged with a green fluorescent protein (GFP) were still capable of transporting GFP into but aggregated abnormally in nuclei. Our data establish that zinc- and DNA-binding activity correlates with C2-mediated pathogenesis and PTGS suppression.

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