Fertile Hypomorphic ARGONAUTE (ago1) Mutants Impaired in Post-Transcriptional Gene Silencing and Virus Resistance

We showed previously that transgenic plants with the green fluorescent protein (GFP) gene fused to segments of the nucleocapsid (N) gene of tomato spotted wilt virus (TSWV) displayed post-transcriptional gene silencing of the GFP and N gene segments and resistance to TSWV. These results suggested that a chimeric transgene composed of viral gene segments might confer multiple virus resistance in transgenic plants. To test this hypothesis and to determine the minimum length of the N gene that could trans-inactivate the challenging TSWV, transgenic plants were developed that contained GFP fused with N gene segments of 24–453 bp. Progeny from these plants were challenged with: (i) a chimeric tobacco mosaic virus containing the GFP gene, (ii) a chimeric tobacco mosaic virus with GFP plus the N gene of TSWV and (iii) TSWV. A number of transgenic plants expressing the transgene with GFP fused to N gene segments from 110 to 453 bp in size were resistant to these viruses. Resistant plants exhibited post-transcriptional gene silencing. In contrast, all transgenic lines with transgenes consisting of GFP fused to N gene segments of 24 or 59 bp were susceptible to TSWV, even though the transgene was post-transcriptionally silenced. Thus, virus resistance and post-transcriptional gene silencing were uncoupled when the N gene segment was 59 bp or less. These results provide evidence that multiple virus resistance is possible through the simple strategy of linking viral gene segments to a silencer DNA such as GFP.

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Soybean Mosaic Virus Resistance in Transgenic Soybean Caused by Post-transcriptional Gene Silencing

Breeding Science ◽

10.1270/jsbbs.57.123 ◽

2007 ◽

Vol 57 (2) ◽

pp. 123-128 ◽

Cited By ~ 20

Author(s):

Noriyuki Furutani ◽

Noriko Yamagishi ◽

Soh Hidaka ◽

Yoshiaki Shizukawa ◽

Seiji Kanematsu ◽

...

Keyword(s):

Gene Silencing ◽

Mosaic Virus ◽

Virus Resistance ◽

Soybean Mosaic Virus ◽

Transcriptional Gene Silencing ◽

Transgenic Soybean ◽

Post Transcriptional Gene Silencing

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Sequence-Specific Post-Transcriptional Gene Silencing by Double-Stranded RNA

Encyclopedic Reference of Genomics and Proteomics in Molecular Medicine ◽

10.1007/3-540-29623-9_5911 ◽

2006 ◽

pp. 1744-1744

Keyword(s):

Gene Silencing ◽

Transcriptional Gene Silencing ◽

Double Stranded Rna ◽

Post Transcriptional Gene Silencing

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Transgenic resistance in potato plants expressing potato leaf roll virus (PLRV) replicase gene sequences is RNA-mediated and suggests the involvement of post-transcriptional gene silencing

Archives of Virology ◽

10.1007/s007050170095 ◽

2001 ◽

Vol 146 (7) ◽

pp. 1337-1353 ◽

Cited By ~ 22

Author(s):

C. Vazquez Rovere ◽

S. Asurmendi ◽

H. E. Hopp

Keyword(s):

Gene Silencing ◽

Leaf Roll ◽

Potato Leaf Roll Virus ◽

Transcriptional Gene Silencing ◽

Replicase Gene ◽

Transgenic Resistance ◽

Gene Sequences ◽

Potato Leaf ◽

Potato Plants ◽

Post Transcriptional Gene Silencing

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Viroids as a Tool to Study RNA-Directed DNA Methylation in Plants

Cells ◽

10.3390/cells10051187 ◽

2021 ◽

Vol 10 (5) ◽

pp. 1187

Author(s):

Michael Wassenegger ◽

Athanasios Dalakouras

Keyword(s):

Dna Methylation ◽

Rna Interference ◽

Gene Silencing ◽

Plant Cells ◽

Transcriptional Gene Silencing ◽

Rnai Machinery ◽

Double Stranded Rna ◽

Post Transcriptional Gene Silencing ◽

Cumulative Amount

Viroids are plant pathogenic, circular, non-coding, single-stranded RNAs (ssRNAs). Members of the Pospiviroidae family replicate in the nucleus of plant cells through double-stranded RNA (dsRNA) intermediates, thus triggering the host’s RNA interference (RNAi) machinery. In plants, the two RNAi pillars are Post-Transcriptional Gene Silencing (PTGS) and RNA-directed DNA Methylation (RdDM), and the latter has the potential to trigger Transcriptional Gene Silencing (TGS). Over the last three decades, the employment of viroid-based systems has immensely contributed to our understanding of both of these RNAi facets. In this review, we highlight the role of Pospiviroidae in the discovery of RdDM, expound the gradual elucidation through the years of the diverse array of RdDM’s mechanistic details and propose a revised RdDM model based on the cumulative amount of evidence from viroid and non-viroid systems.

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Epigenetic Changes in Host Ribosomal DNA Promoter Induced by an Asymptomatic Plant Virus Infection

Biology ◽

10.3390/biology9050091 ◽

2020 ◽

Vol 9 (5) ◽

pp. 91 ◽

Cited By ~ 1

Author(s):

Miryam Pérez-Cañamás ◽

Elizabeth Hevia ◽

Carmen Hernández

Keyword(s):

Gene Silencing ◽

Ribosomal Dna ◽

Plant Virus ◽

Dna Methyltransferase ◽

Cytosine Methylation ◽

De Novo ◽

Methylation Pattern ◽

Transcriptional Gene Silencing ◽

Post Transcriptional Gene Silencing ◽

The Impact

DNA cytosine methylation is one of the main epigenetic mechanisms in higher eukaryotes and is considered to play a key role in transcriptional gene silencing. In plants, cytosine methylation can occur in all sequence contexts (CG, CHG, and CHH), and its levels are controlled by multiple pathways, including de novo methylation, maintenance methylation, and demethylation. Modulation of DNA methylation represents a potentially robust mechanism to adjust gene expression following exposure to different stresses. However, the potential involvement of epigenetics in plant-virus interactions has been scarcely explored, especially with regard to RNA viruses. Here, we studied the impact of a symptomless viral infection on the epigenetic status of the host genome. We focused our attention on the interaction between Nicotiana benthamiana and Pelargonium line pattern virus (PLPV, family Tombusviridae), and analyzed cytosine methylation in the repetitive genomic element corresponding to ribosomal DNA (rDNA). Through a combination of bisulfite sequencing and RT-qPCR, we obtained data showing that PLPV infection gives rise to a reduction in methylation at CG sites of the rDNA promoter. Such a reduction correlated with an increase and decrease, respectively, in the expression levels of some key demethylases and of MET1, the DNA methyltransferase responsible for the maintenance of CG methylation. Hypomethylation of rDNA promoter was associated with a five-fold augmentation of rRNA precursor levels. The PLPV protein p37, reported as a suppressor of post-transcriptional gene silencing, did not lead to the same effects when expressed alone and, thus, it is unlikely to act as suppressor of transcriptional gene silencing. Collectively, the results suggest that PLPV infection as a whole is able to modulate host transcriptional activity through changes in the cytosine methylation pattern arising from misregulation of methyltransferases/demethylases balance.

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An atypical class of non-coding small RNAs produced in rice leaves upon bacterial infection

10.1101/2021.03.05.432875 ◽

2021 ◽

Author(s):

Ganna Reshetnyak ◽

Jonathan M. Jacobs ◽

Florence Auguy ◽

Coline Sciallano ◽

Lisa Claude ◽

...

Keyword(s):

Gene Silencing ◽

Stress Responses ◽

Small Rnas ◽

Early Stage ◽

Kinase Domain ◽

Transcriptional Gene Silencing ◽

Small Interfering Rnas ◽

Post Transcriptional Gene Silencing ◽

Virulent Strains ◽

Microbe Interactions

ABSTRACTNon-coding small RNAs (sRNA) act as mediators of gene silencing and regulate plant growth, development and stress responses. Early insights into plant sRNAs established a role in antiviral defense and they are now extensively studied across plant-microbe interactions. Here, sRNA sequencing discovered a class of sRNA in rice (Oryza sativa) specifically associated with foliar diseases caused by Xanthomonas oryzae bacteria. Xanthomonas-induced small RNAs (xisRNAs) loci were distinctively upregulated in response to diverse virulent strains at an early stage of infection producing a single duplex of 20-22nt sRNAs. xisRNAs production was dependent on the Type III secretion system, a major bacterial virulence factor for host colonization. xisRNA loci overlap with annotated transcripts sequences often encoding protein kinase domain proteins. A number of the corresponding rice cis-genes have documented functions in immune signaling and some xisRNA loci coincide with the coding sequence of a conserved kinase motif. xisRNAs exhibit features of small interfering RNAs and their biosynthesis depend on canonical components OsDCL1 and OsHEN1. xisRNA induction possibly mediates post-transcriptional gene silencing but they do not broadly suppress cis-genes expression on the basis of mRNA-seq data. Overall, our results identify a group of unusual sRNAs with a potential role in plant-microbe interactions.

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