Epigenomic profiles of Brachypodium distachyon mutants deficient in RNA polymerase IV (Pol IV)
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ABSTRACT:
ORGANISM(S): Brachypodium distachyon
PROVIDER: GSE243693 | GEO | 2024/03/04
REPOSITORIES: GEO
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Project description:In Arabidopsis thaliana, DNA-dependent RNA polymerase IV (Pol IV) is required for the formation of transposable element (TE)-derived small RNA (sRNA) transcripts. These transcripts are processed by DICER-LIKE3 into 24-nt small interfering RNAs (siRNAs) that guide RNA-directed DNA methylation. In the pollen grain, Pol IV is also required for the accumulation of 21/22-nt epigenetically activated siRNAs (easiRNAs), which likely silence TEs via post-transcriptional mechanisms. Despite this proposed role of Pol IV, its loss of function in Arabidopsis does not cause a discernable pollen defect. Here, we show that the knockout of NRPD1, encoding the largest subunit of Pol IV in the Brassicaceae species Capsella rubella, caused post-meiotic arrest of pollen development at the microspore stage. As in Arabidopsis, all TE-derived siRNAs were 2 depleted in Capsella nrpd1 microspores. In the wild-type background, the same TEs produced 21/22-nt and 24-nt siRNAs; these processes required Pol IV activity. Arrest of Capsella nrpd1 microspores was accompanied by the deregulation of genes targeted by Pol IV-dependent siRNAs. TEs were much closer to genes in Capsella rubella compared to Arabidopsis thaliana, perhaps explaining the essential role of Pol IV in pollen development in Capsella. Our discovery that Pol IV is functionally required in Capsella microspores emphasizes the relevance of investigating different plant models.
2020-01-23 | GSE136847 | GEO
Project description:DNA methylation is an epigenetic modification that plays critical roles in gene silencing, development, and the maintenance of genome integrity. In Arabidopsis, DNA methylation is established by DOMAINS REARRANGED METHYLTRANSFERASE 2 (DRM2) and is targeted by 24 nt small interfering RNAs (siRNAs) through a pathway termed RNA-directed DNA methylation (RdDM)1. This pathway requires two plant-specific RNA polymerases: Pol-IV, which functions to initiate siRNA biogenesis and Pol-V, which functions in the downstream DNA methyltransferase targeting phase of the RdDM pathway to generate scaffold transcripts that recruit downstream RdDM factors1,2. To understand the mechanisms controlling Pol-IV targeting we investigated the function of SAWADEE HOMEODOMAIN HOMOLOG 1 (SHH1)3,4, a Pol-IV interacting protein3. Here we show that SHH1 acts upstream in the RdDM pathway to enable siRNA production from a large subset of the most active RdDM targets and that SHH1 is required for Pol-IV occupancy at these same loci. We also show that the SHH1 SAWADEE domain is a novel chromatin binding module that adopts a unique tandem Tudor-like fold and functions as a dual lysine reader, probing for both unmethylated K4 and methylated K9 modifications on the histone 3 (H3) tail. Finally, we show that key residues within both lysine binding pockets of SHH1 are required in vivo to maintain siRNA and DNA methylation levels as well as Pol-IV occupancy at RdDM targets, demonstrating a central role for methyl H3K9 binding in SHH1 function and providing the first insights into the mechanism of Pol-IV targeting. Given the parallels between methylation systems in plants and mammals1,5, a further understanding of this early targeting step may aid in our ability to control the expression of endogenous and newly introduced genes, which has broad implications for agriculture and gene therapy. For wild type plants (ecotype Columbia) and RdDM mutants whole-genome small RNA (sRNA-seq) and bisulfite sequencing (BS-seq) was performed. The Col and nrpe1 BS-seq libraries were previously reported (GSE39247) and so are not part of this submission. In addition, two replicates of whole genome chromatin immunoprecipitation (ChIP-seq) was performed on wild type (ecotype Columbia) plants as a negative control with experimentals consiting of nrpd1 mutant plants carrying a C-terminally epitope tagged (3XFLAG) NRPD1. Whole-genome bisulfite sequencing and small RNA sequencing was also performed on shh1 mutant plants transformed with the wild-type SHH1 protein-coding construct as well as multiple constructs containing point mutations. For these complementation libraries a separate shh1 mutant and Col control line were sequenced (“complementation replicates”).
2013-05-13 | E-GEOD-45368 | biostudies-arrayexpress
Project description:24 nucleotide siRNAs are central players in RNA-directed DNA methylation (RdDM), a process that establishes DNA methylation at transposable elements to ensure genome stability. The plant-specific RNA polymerase IV (Pol IV) is required for siRNA biogenesis and is thought to transcribe RdDM loci to produce primary transcripts that serve as precursors to siRNAs. Yet, no such transcripts have ever been reported. Here, through RNA sequencing and double-stranded RNA sequencing in genotypes that compromise the dicing of siRNA precursors, we were able to identify Pol IV-dependent transcripts from tens of thousands of loci. We show that Pol IV-dependent transcripts correspond to both DNA strands, while the Pol II-dependent transcripts produced upon de-repression of the loci are derived from primarily one strand. We show that Pol IV-dependent transcripts have a 5â monophosphate, lack a polyA tail at the 3â end, and contain no introns; these features distinguish them from Pol II-dependent transcripts. Moreover, RDR2 is shown to play similar roles with Pol IV in both the abundance of siRNA precursors and siRNAs as well as the CHH DNA methylation. The decreased CHH methylation at dcl234 can inhibit the transcription of Pol IV at DRM2-target sites. Finally, the regulations of siRNA biogenesis were explored. To detect siRNA precursors transcribed by RNA polymerase IV, the genome wide profiling of RNA were carried out at dcl234 and dcl234 nrpd1. Different types of RNA (including Total RNA, polyA+ RNA, polyA- RNA, double stranded RNA) libraries were built to detect different transcripts. RDR2 is a RNA-dependent RNA polymerase in Pol IV complex, so the RNA-seq libraries with the mutation of RDR2 were also built. In addition, smRNA libraries with mutations blocking siRNA biogenesis were also built
2014-11-11 | E-GEOD-57215 | biostudies-arrayexpress
Project description:DNA methylation is an important epigenetic mark in many eukaryotic organisms. De novo DNA methylation in plants can be achieved by the RNA-directed DNA methylation (RdDM) pathway, where the plant-specific DNA-dependent RNA polymerase Pol IV transcribes target sequences to initiate 24-nt siRNA production and action. The Arabidopsis DTF1/SHH1 has been shown to associate with Pol IV and is required for 24-nt siRNA accumulation and transcriptional silencing at several RdDM target loci. However, the extent and mechanism of DTF1 function in RdDM is unclear. We show here that DTF1 is necessary for the accumulation of the majority of Pol IV-dependent 24-nt siRNAs. It is also required for a large proportion of Pol IV-dependent de novo DNA methylation. Interestingly, there is a group of RdDM target loci where 24-nt siRNA accumulation but not DNA methylation is dependent on DTF1. Taken together, our results show that DTF1 is a core component of the RdDM pathway. Our results also suggest the involvement of DTF1 in an important negative feedback mechanism for DNA methylation at some RdDM target loci. Examination of whole-genome DNA methylation and small RNA in 12-day-old Col-0, dtf1-2, nrpd1-3 and nrpe1-11 seedlings
2013-06-03 | E-GEOD-44209 | biostudies-arrayexpress
Project description:The Arabidopsis thaliana multi-subunit RNA Polymerase IV largest subunit DeCL domain was functionally assessed with an NRPD1 DeCL domain deletion construct.
2017-07-17 | GSE95824 | GEO
Project description:The Arabidopsis thaliana multi-subunit RNA Polymerase IV largest subunit DeCL domain was functionally assessed with an NRPD1 DeCL domain deletion construct.
2017-07-17 | GSE95823 | GEO
Project description:Background: Plant-unique RNA polymerase IV (Pol IV) governs the establishment of small RNA-directed DNA methylation (RdDM) and contributes to the maintenance of transposable element (TE) silencing. Pol IV-dependent RdDM is highly active during embryonic development, and its absence occasionally reduces seed sets in species with high TE content. However, the mechanism underlying embryonic development failure due to the loss of Pol IV-RdDM remains largely unclear. Results: Here, we report that the loss-of-function of SlNRPD1, encoding the largest subunit of the Pol IV complex leads to aberrant embryogenesis in tomato (Solanum lycopersicum). The slnrpd1 mutants show non-CG hypomethylation and a burst of 21/22-nt sRNA from the distal chromatin region. We found that non-CG hypomethylation at the gene body region is generally associated with the activation of transcription, and knocking out DEMETER-like DNA demethylases cannot reverse slnrpd1 embryo lethality. mCHH hypomethylation in slnrpd1 disrupts gene expression related to auxin and WUSCHEL-related homeobox (WOX) signaling. TE reactivation in slnrpd1 mainly affects the expression of a limited number of nearby genes rather than contributing to excessive sRNA. Conclusion: We conclude that Pol IV-mediated RdDM is essential for tomato embryogenesis via non-CG methylation. mCHH hypomethylation in the slnrpd1 embryo leads to abnormal auxin/WOX signaling and TE reactivation which probably disrupts the tissue and organ initiation. This study provides new insights into the epigenetic regulation of gene and TE expression during embryogenesis. Keywords: DNA methylation, RdDM, NRPD1, Embryogenesis, Tomato
2024-10-01 | GSE246015 | GEO
Project description:Background: Plant-unique RNA polymerase IV (Pol IV) governs the establishment of small RNA-directed DNA methylation (RdDM) and contributes to the maintenance of transposable element (TE) silencing. Pol IV-dependent RdDM is highly active during embryonic development, and its absence occasionally reduces seed sets in species with high TE content. However, the mechanism underlying embryonic development failure due to the loss of Pol IV-RdDM remains largely unclear. Results: Here, we report that the loss-of-function of SlNRPD1, encoding the largest subunit of the Pol IV complex leads to aberrant embryogenesis in tomato (Solanum lycopersicum). The slnrpd1 mutants show non-CG hypomethylation and a burst of 21/22-nt sRNA from the distal chromatin region. We found that non-CG hypomethylation at the gene body region is generally associated with the activation of transcription, and knocking out DEMETER-like DNA demethylases cannot reverse slnrpd1 embryo lethality. mCHH hypomethylation in slnrpd1 disrupts gene expression related to auxin and WUSCHEL-related homeobox (WOX) signaling. TE reactivation in slnrpd1 mainly affects the expression of a limited number of nearby genes rather than contributing to excessive sRNA. Conclusion: We conclude that Pol IV-mediated RdDM is essential for tomato embryogenesis via non-CG methylation. mCHH hypomethylation in the slnrpd1 embryo leads to abnormal auxin/WOX signaling and TE reactivation which probably disrupts the tissue and organ initiation. This study provides new insights into the epigenetic regulation of gene and TE expression during embryogenesis. Keywords: DNA methylation, RdDM, NRPD1, Embryogenesis, Tomato
2024-10-01 | GSE246017 | GEO
Project description:Background: Plant-unique RNA polymerase IV (Pol IV) governs the establishment of small RNA-directed DNA methylation (RdDM) and contributes to the maintenance of transposable element (TE) silencing. Pol IV-dependent RdDM is highly active during embryonic development, and its absence occasionally reduces seed sets in species with high TE content. However, the mechanism underlying embryonic development failure due to the loss of Pol IV-RdDM remains largely unclear. Results: Here, we report that the loss-of-function of SlNRPD1, encoding the largest subunit of the Pol IV complex leads to aberrant embryogenesis in tomato (Solanum lycopersicum). The slnrpd1 mutants show non-CG hypomethylation and a burst of 21/22-nt sRNA from the distal chromatin region. We found that non-CG hypomethylation at the gene body region is generally associated with the activation of transcription, and knocking out DEMETER-like DNA demethylases cannot reverse slnrpd1 embryo lethality. mCHH hypomethylation in slnrpd1 disrupts gene expression related to auxin and WUSCHEL-related homeobox (WOX) signaling. TE reactivation in slnrpd1 mainly affects the expression of a limited number of nearby genes rather than contributing to excessive sRNA. Conclusion: We conclude that Pol IV-mediated RdDM is essential for tomato embryogenesis via non-CG methylation. mCHH hypomethylation in the slnrpd1 embryo leads to abnormal auxin/WOX signaling and TE reactivation which probably disrupts the tissue and organ initiation. This study provides new insights into the epigenetic regulation of gene and TE expression during embryogenesis. Keywords: DNA methylation, RdDM, NRPD1, Embryogenesis, Tomato
2024-10-01 | GSE246016 | GEO
Project description:The Poaceae family, also known as the grasses, includes agronomically important cereal crops such as rice, maize, sorghum, and wheat. Previous comparative studies have shown that much of the gene content is shared among the grasses; however, functional conservation of orthologous genes has yet to be explored. To gain an understanding of the genome-wide patterns of evolution of gene expression across reproductive tissues, we employed a sequence-based approach to compare analogous transcriptomes in species representing three Poaceae subgroups including the Pooideae (Brachypodium distachyon), the Panicoideae (sorghum), and the Ehrhartoideae (rice). Our transcriptome analyses reveal that only a fraction of orthologous genes exhibit conserved expression patterns. A high proportion of conserved orthologs include genes that are upregulated in physiologically similar tissues such as leaves, anther, pistil, and embryo, while orthologs that are highly expressed in seeds show the most diverged expression patterns. This experiment is related to E-MTAB-4400 (http://www.ebi.ac.uk/arrayexpress/experiments/E-MTAB-4400/) and E-MTAB-4402 (http://www.ebi.ac.uk/arrayexpress/experiments/E-MTAB-4402/)
2012-04-04 | E-MTAB-4401 | biostudies-arrayexpress