Arabidopsis thaliana
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA300285 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR2831350.fastq.gz | Fastqsanger.gz | |||
| SRR2831360.fastq.gz | Fastqsanger.gz | |||
| SRR2831370.fastq.gz | Fastqsanger.gz | |||
| SRR2831380.fastq.gz | Fastqsanger.gz | |||
| SRR2831390.fastq.gz | Fastqsanger.gz |
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Project description:DNA methylation directed by 24-nucleotide (nt) small interfering RNAs (siRNAs) plays critical roles in gene regulation and transposon silencing in Arabidopsis. Twenty-four-nt siRNAs are known to be processed from double-stranded RNAs by Dicer-like 3 (DCL3) and loaded into the effector Argonaute 4 (AGO4). Here we report a distinct class of siRNAs independent of DCLs (sidRNAs). sidRNAs are present as ladders of ~20 to 60nt in length, often having same 5' ends but differing in 3' ends by 1-nt steps. We further show that sidRNAs are associated with AGO4 and capable of directing DNA methylation. Finally we show that sidRNA production depends on AGO4 and distributive 3'-5' exonucleases. Our findings suggest an alternative route for siRNA biogenesis: precursor transcripts are bound by AGO4 and subsequently subjected to 3'-5' exonucleolytic trimming for maturation. We propose that sidRNAs generated through this route are the initial triggers of de novo DNA methylation. Small RNAs were profiled in Arabidopsis wild type (Col-0), dcl1/2/3/4 and other mutants by Illumina high-throughput sequencing, to identify siRNAs independent of DCLs (sidRNAs) and dissect their biogenesis pathway. DNA methylation was profiled in various mutants by whole-genome bisulfite sequencing to establish a role for sidRNAs in DNA methylation
2015-12-17 | E-GEOD-74398 | biostudies-arrayexpress
Project description:DNA methylation directed by 24-nucleotide (nt) small interfering RNAs (siRNAs) plays critical roles in gene regulation and transposon silencing in Arabidopsis. Twenty-four-nt siRNAs are known to be processed from double-stranded RNAs by Dicer-like 3 (DCL3) and loaded into the effector Argonaute 4 (AGO4). Here we report a distinct class of siRNAs independent of DCLs (sidRNAs). sidRNAs are present as ladders of ~20 to 60nt in length, often having same 5' ends but differing in 3' ends by 1-nt steps. We further show that sidRNAs are associated with AGO4 and capable of directing DNA methylation. Finally we show that sidRNA production depends on AGO4 and distributive 3'-5' exonucleases. Our findings suggest an alternative route for siRNA biogenesis: precursor transcripts are bound by AGO4 and subsequently subjected to 3'-5' exonucleolytic trimming for maturation. We propose that sidRNAs generated through this route are the initial triggers of de novo DNA methylation.
2015-12-17 | GSE74398 | GEO
Project description:Dicer-independent RNA-directed DNA methylation in Arabidopsis [methylC-seq]
| PRJNA289907 | ENA
Project description:The Arabidopsis genome contains a highly complex and abundant population of small RNAs, and many of the endogenous siRNAs are dependent on RNA-DEPENDENT RNA POLYMERASE 2 (RDR2) for their biogenesis. By analyzing an rdr2 loss-of-function mutant using two different parallel sequencing technologies, MPSS and 454, we characterized the complement of miRNAs expressed in Arabidopsis inflorescence to considerable depth. Nearly all known miRNAs were enriched in this mutant and we identified 13 new miRNAs, all of which were relatively low abundance and constitute new families. Trans-acting siRNAs (ta-siRNAs) were even more highly enriched. Computational and gel blot analyses suggested that the minimal number of miRNAs in Arabidopsis is approximately 155. The size profile of small RNAs in rdr2 reflected enrichment of 21-nt miRNAs and other classes of siRNAs like ta-siRNAs, and a significant reduction in 24-nt heterochromatic siRNAs. Other classes of small RNAs were found to be RDR2-independent, particularly those derived from long inverted repeats and a subset of tandem repeats. The small RNA populations in other Arabidopsis small RNA biogenesis mutants were also examined; a dcl2/3/4 triple mutant showed a similar pattern to rdr2, whereas dcl1-7 and rdr6 showed reductions in miRNAs and ta-siRNAs consistent with their activities in the biogenesis of these types of small RNAs. Deep sequencing of mutants provides a genetic approach for the dissection and characterization of diverse small RNA populations and the identification of low abundance miRNAs. Keywords: small RNA sequences generated by 454 sequencing
2006-09-08 | GSE5343 | GEO
Project description:Dicer-independent RNA-directed DNA methylation in Arabidopsis [small RNA-seq 1]
| PRJNA289906 | ENA
Project description:Dicer-independent RNA-directed DNA methylation in Arabidopsis [small RNA-seq 2]
| PRJNA291775 | ENA
Project description:In Arabidopsis thaliana, four different DICER-LIKE (DCL) proteins have distinct, but partially overlapping functions in the biogenesis of microRNAs (miRNAs) and small interfering RNAs (siRNAs) from longer, non-coding precursor RNAs. To analyze the impact of different components of the small RNA (sRNA) biogenesis machinery on the transcriptome, we subjected dcl and other mutants impaired in sRNA biogenesis to whole-genome tiling array analysis. We compared both protein-coding genes and noncoding transcripts, including most pri-miRNAs, in two tissues and several stress conditions. We discovered distinct effects of dcl1, hyl1 and se mutations on the transcriptome, as well as a number of common genes affected in dcl1 and dcl2 dcl3 dcl4 triple mutants. Our results furthermore suggest that the DCL1 is not only involved in miRNA action, but can also contribute to silencing of certain transposons, apparently through an effect on DNA methylation. Together, our findings contribute to the knowledge of both specialization and overlap between different RNA silencing pathways.
2010-05-08 | GSE21685 | GEO
Project description:Parallel RNA silencing pathways regulate gene expression in plants, either by transcriptional gene silencing via RNA-dependent DNA methylation (RdDM), or by post-transcriptional silencing targeting mRNAs. Both pathways rely on distinct Dicer-like proteins to cleave double-stranded RNA into small-interfering RNAs. Experiments to determine the subcellular localization of Dicer-like proteins in Arabidopsis revealed that DCL4 is predominantly expressed as a transcriptional start site isoform that encodes a cytoplasmic protein. A second, longer DCL4 transcript isoform encodes a nuclear-localization signal and its expression is repressed by DNA methylation. Consequently this isoform is induced when promoter methylation decreases due to infection with a bacterial pathogen or during silique development. Nuclear DCL4 produces unique populations of small RNAs, called DCL4NLS isoform-dependent siRNAs (disiRNAs), which function via a post-transcriptional silencing effector, but whose precursors are generated by the RdDM pathway. Arabidopsis cells can thus respond to genome methylation changes by modulating DCL4 localization, which in turn recruits PTGS factors to reinforce RNA silencing.
2016-11-14 | GSE74731 | GEO
Project description:In plants, RNA polymerase II (Pol II) transcription of inverted DNA repeats produces hairpin RNAs that are processed by several DICER-LIKE enzymes into siRNAs that are 21-24-nt in length. When targeted to transcriptional regulatory regions, the 24-nt size class can induce RNA-directed DNA methylation (RdDM) and transcriptional gene silencing (TGS). In a forward genetic screen to identify mutants defective in RdDM of a target enhancer leading to TGS of a downstream GFP reporter gene in Arabidopsis thaliana, we recovered a structurally mutated silencer locus, named SM-NM-^T35S, in which the 35S promoter driving transcription of an inverted repeat of target enhancer sequences had been specifically deleted. Although Pol II-dependent, hairpin-derived 21-24-nt siRNAs were no longer generated at the newly created SM-NM-^T35S locus, the GFP reporter gene was nevertheless still partially silenced. Silencing was associated with methylation in a short tandem repeat in the upstream target enhancer and with low levels of 24-nt tandem repeat siRNAs. Introducing an nrpd1 mutation into the SM-NM-^T35S line fully released GFP silencing and eliminated both the tandem repeat methylation and associated 24-nt siRNAs, demonstrating their dependence on Pol IV. Deletion of the 35S promoter thus revealed a Pol IV-dependent pathway of 24-nt siRNA biogenesis that was previously inhibited or masked by the Pol II-dependent pathway in wild-type plants. Both Pol II- and Pol IV-dependent siRNAs accrued predominantly from cytosine (C)-containing segments of the tandem repeat monomer, suggesting that the local base composition influenced siRNA accumulation. Preferential accumulation of siRNAs at C-containing sequences was also observed at an endogenous tandem repeat comprising discrete C-rich and AT-rich sections. Our studies illuminate the potential complexity of siRNA generation at repeat-containing loci and show that Pol IV can act in siRNA biogenesis in the absence of a conventional Pol II promoter. Examination of whole-genome DNA methylation status in transgenic T+S Arabidopsis plant
2013-05-30 | E-GEOD-47453 | biostudies-arrayexpress
Project description:RNA-directed DNA methylation (RdDM) is a small interfering RNA (siRNA)-mediated epigenetic modification that contributes to transposon silencing in plants. RdDM requires a complex transcriptional machinery that includes specialized RNA polymerases, named Pol IV and Pol V, as well as chromatin remodelling proteins, transcription factors, RNA binding proteins, and other plant-specific proteins whose functions are not yet clarified. In Arabidopsis thaliana, DICER-LIKE3 and members of the ARGONAUTE4 group of AROGONAUTE (AGO) proteins are involved, respectively, in generating and using 24-nt siRNAs that trigger methylation and transcriptional gene silencing (TGS) of homologous promoter sequences. AGO proteins act in silencing effector complexes by anchoring the 3â and 5â ends of the guide siRNAs at their N-terminal PAZ domain and MID domain, respectively. In addition, many AGO proteins cleave complementary target RNAs through an endonuclease (âslicerâ) activity in their C-terminal PIWI domain. AGO4 is the main AGO protein implicated in the RdDM pathway. Here we report the identification of the related AGO6 in a forward genetic screen for mutants defective in RdDM and TGS in shoot and root apical meristems in Arabidopsis thaliana. The identification of AGO6, and not AGO4, in our screen is consistent with the primary expression of AGO6 in shoot and root growing points and the preferential association of Pol V with AGO6.
2011-12-01 | GSE28537 | GEO