Deep sequencing of small RNAs in the trasngenic wild type plant and the IWR1-type transcription factor mutant, dms4
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ABSTRACT:
ORGANISM(S): Arabidopsis thaliana
PROVIDER: GSE18302 | GEO | 2010/03/31
SECONDARY ACCESSION(S): PRJNA118033
REPOSITORIES: GEO
Similar Datasets
Project description:Full title: Deep sequencing of small RNAs in the trasngenic wild type plant (contains trigger and silencer transgenes) and the IWR1-type transcription factor mutant, dms4 RNA-directed DNA methylation (RdDM) in plants requires two RNA polymerase II (PolII)-related RNA polymerases named PolIV and PolV. A genetic screen designed to reveal factors important for RdDM in a developmental context in Arabidopsis identified DEFECTIVE IN MERISTEM SILENCING 4 (DMS4). Unlike other mutants defective in RdDM, dms4 mutants have a pleiotropic developmental phenotype.DMS4 is similar to yeast IWR1, a conserved putative transcription factor that interacts with PolII subunits. In the transgenic system studied, mutations in DMS4 directly or indirectly affect PolIV-dependent secondary siRNAs, PolV-mediated RdDM, PolV-dependent synthesis of intergenic noncoding RNA, and expression of many PolII-driven genes. These data suggest that DMS4 may be a regulatory factor for multiple RNA polymerases, thus explaining its diverse roles in the plant. Examination of siRNA abundance in the trasngenic wild type plant (contains trigger and silencer transgenes) and the dms4 mutant.
2010-03-31 | E-GEOD-18302 | biostudies-arrayexpress
Project description:Background: The majority of plant transposable elements (TEs) are found in a silenced state that is epigenetically propagated by the maintenance of symmetrical DNA methylation. TE methylation is established and reinforced by a mechanism of RNA-dependent DNA methylation, which is dependent on transcription of the PolIV RNA polymerase. Recently, a pathway has been described that initiates de novo DNA methylation dependent on components of the RNAi post-transcriptional silencing pathway, independent of PolIV. To define the function of this new pathway, we have focused on the RDR6 protein, which plays a central role in the pathway we refer to as RDR6-dependent RNA-directed DNA Methylation (RDR6-RdDM). Methods: We have sequenced total small RNAs from wild-type and three mutant genotypes: ddm1, ddm1/rdr6, and rdr6. Conclusions: We demonstrate that RDR6-RdDM utilizes 21 and 22 nucleotide siRNAs to de novo methylate actively transcribing TEs. In addition, we find that the RDR6-RdDM pathway functions in the efficient initiation and re-establishment of TE transcriptional silencing, while it is not necessary to maintain trans-generational epigenetic silencing. Examination of flower bud small RNAs from wild-type and 3 mutant genotypes
2013-04-11 | E-GEOD-41755 | biostudies-arrayexpress
Project description:The C-REPEAT-BINDING FACTOR (CBF) pathway has important roles in plant responses to cold stress. Previous research documented that constitutively expressed upstream transcription factors are activated by cold stress to induce the expression of CBF genes and the resulting CBF proteins trigger the expression of downstream cold responsive genes that confer freezing tolerance. In the present study, we found that dysfunction of RNA-DIRECTED DNA METHYLATION 4 (RDM4), which encodes a protein that associates with RNA polymerases Pol IV and Pol V as well as Pol II, and is required for RNA-directed DNA methylation (RdDM) and proper plant development in Arabidopsis, reduced chilling and freezing tolerance in Arabidopsis as evidenced by decreased survival and increased electrolyte leakage under cold stress conditions. CBFs and CBF regulon genes were down-regulated in rdm4 but not nrpe1 (the largest subunit of PolV) mutant plants, suggesting that the role of RDM4 in cold stress responses is independent of the RdDM pathway. Overexpression of RDM4 increased the expression of CBFs and CBF regulon genes and decreased cold-induced membrane injury. The rdm4 mutants exhibited decreased antioxidant enzyme activities and increased accumulation of reactive oxygen species. Microarray analysis indicated that a great proportion of genes affected by rdm4 overlapped with those affected by CBF2 and CBF3 in Arabidopsis. Chromatin immunoprecipitation (ChIP) results suggested that RDM4 is important for Pol II occupancy at the promoters of CBF genes but not the promoters of up-stream regulators of CBFs. Together, these data indicate that RDM4 acts as a component of a Pol II transcription complex that regulates CBF gene expression and cold stress resistance in Arabidopsis. Two-week-old seedlings of rdm4 and C24 WT plant were subjected to chilling treatment for 0, 3, and 48 h treatments.Plant materials were then collected for RNA extraction.
2016-06-30 | E-GEOD-63185 | biostudies-arrayexpress
Project description:The C-REPEAT-BINDING FACTOR (CBF) pathway has important roles in plant responses to cold stress. Previous research documented that constitutively expressed upstream transcription factors are activated by cold stress to induce the expression of CBF genes and the resulting CBF proteins trigger the expression of downstream cold responsive genes that confer freezing tolerance. In the present study, we found that dysfunction of RNA-DIRECTED DNA METHYLATION 4 (RDM4), which encodes a protein that associates with RNA polymerases Pol IV and Pol V as well as Pol II, and is required for RNA-directed DNA methylation (RdDM) and proper plant development in Arabidopsis, reduced chilling and freezing tolerance in Arabidopsis as evidenced by decreased survival and increased electrolyte leakage under cold stress conditions. CBFs and CBF regulon genes were down-regulated in rdm4 but not nrpe1 (the largest subunit of PolV) mutant plants, suggesting that the role of RDM4 in cold stress responses is independent of the RdDM pathway. Overexpression of RDM4 increased the expression of CBFs and CBF regulon genes and decreased cold-induced membrane injury. The rdm4 mutants exhibited decreased antioxidant enzyme activities and increased accumulation of reactive oxygen species. Microarray analysis indicated that a great proportion of genes affected by rdm4 overlapped with those affected by CBF2 and CBF3 in Arabidopsis. Chromatin immunoprecipitation (ChIP) results suggested that RDM4 is important for Pol II occupancy at the promoters of CBF genes but not the promoters of up-stream regulators of CBFs. Together, these data indicate that RDM4 acts as a component of a Pol II transcription complex that regulates CBF gene expression and cold stress resistance in Arabidopsis. Two-week-old seedlings of 35S::RDM4 and Col WT plant were subjected to chilling treatment for 0, 3, and 48 h treatments.Plant materials were then collected for RNA extraction.
2016-06-30 | E-GEOD-63184 | biostudies-arrayexpress
Project description:Background: The majority of plant transposable elements (TEs) are found in a silenced state that is epigenetically propagated by the maintenance of symmetrical DNA methylation. TE methylation is established and reinforced by a mechanism of RNA-dependent DNA methylation, which is dependent on transcription of the PolIV RNA polymerase. Recently, a pathway has been described that initiates de novo DNA methylation dependent on components of the RNAi post-transcriptional silencing pathway, independent of PolIV. To define the function of this new pathway, we have focused on the RDR6 protein, which plays a central role in the pathway we refer to as RDR6-dependent RNA-directed DNA Methylation (RDR6-RdDM). Methods: We have sequenced total small RNAs from wild-type and three mutant genotypes: ddm1, ddm1/rdr6, and rdr6. Conclusions: We demonstrate that RDR6-RdDM utilizes 21 and 22 nucleotide siRNAs to de novo methylate actively transcribing TEs. In addition, we find that the RDR6-RdDM pathway functions in the efficient initiation and re-establishment of TE transcriptional silencing, while it is not necessary to maintain trans-generational epigenetic silencing.
2013-04-11 | GSE41755 | GEO
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. Examination of siRNA abundance in the trasngenic wild type plant (contains trigger and silencer transgenes) and the ago6-4 mutant.
2011-12-01 | E-GEOD-28537 | biostudies-arrayexpress
Project description:RNA polymerases IV and V (Pol IV and Pol V) are plant-specific polymerases required for the generation of noncoding RNAs in RNA-directed DNA methylation (RdDM) and transcriptional gene silencing. Their subunit compositions largely resemble that of Pol II. However, the mechanism and accessory factors involved in their assembly remain largely unknown. In this study, we performed a forward genetic screen and identified novel mutant alleles of MINIYO (IYO), QUATRE-QUART 2 (QQT2) and NUCLEAR RNA POLYMERASE B/D/E 11 (NRPB/D/E11) that are defective in RdDM. We found that Pol IV-dependent small interfering RNAs (siRNAs) and Pol V-dependent transcripts were greatly reduced in the mutants. NRPE1, the largest subunit of Pol V, dissociated from other Pol V subunits in the iyo and qqt2 mutants, suggesting the involvement of IYO and QQT2 in Pol V assembly. Furthermore, we found that IYO and QQT2 were mutually dependent for their binding to the NRPE3 subassembly to facilitate the assembly of Pol V holoenzyme. Our findings reveal IYO and QQT2 as cofactors for Pol V assembly and provide mechanistic insights into how RNA polymerases are assembled in Arabidopsis.
2018-04-09 | GSE103326 | GEO
Project description:Small RNA-dependent pairing of AGO/PIWI-containing effector complexes to chromatin-bound nascent transcripts has been proposed as a universal mechanism for guiding RNA-mediated TGS in eukaryotes. Likewise, Pol V-dependent transcripts have been implicated in the targeting of AGO4 to chromatin in RNA-directed DNA methylation (RdDM) in plants. Here, we show that the AGO hook platforms of PolV and SPT5L, another component of the transcriptional complex, are functionally redundant yet essential for RdDM at a genome-wide level. Synthesis of Pol V transcripts is uncoupled from AGO4 recruitment in AGO hook-minus plants, challenging the prevailing RNA-based mechanism of AGO4 targeting to chromatin in RdDM. Transcription is essential to lock the PolV transcription complex into a stable and productive DNA-bound state potentiating interactions of AGO4 with DNA. Consistent with this idea, laser UV-assisted crosslinking shows specific AGO4-DNA interaction at RdDM loci, suggesting a revised model for Pol V-mediated DNA methylation in plants, which explains the exquisite specificity of methylation.
2015-06-01 | GSE67216 | GEO
Project description:The C-REPEAT-BINDING FACTOR (CBF) pathway has important roles in plant responses to cold stress. Previous research documented that constitutively expressed upstream transcription factors are activated by cold stress to induce the expression of CBF genes and the resulting CBF proteins trigger the expression of downstream cold responsive genes that confer freezing tolerance. In the present study, we found that dysfunction of RNA-DIRECTED DNA METHYLATION 4 (RDM4), which encodes a protein that associates with RNA polymerases Pol IV and Pol V as well as Pol II, and is required for RNA-directed DNA methylation (RdDM) and proper plant development in Arabidopsis, reduced chilling and freezing tolerance in Arabidopsis as evidenced by decreased survival and increased electrolyte leakage under cold stress conditions. CBFs and CBF regulon genes were down-regulated in rdm4 but not nrpe1 (the largest subunit of PolV) mutant plants, suggesting that the role of RDM4 in cold stress responses is independent of the RdDM pathway. Overexpression of RDM4 increased the expression of CBFs and CBF regulon genes and decreased cold-induced membrane injury. The rdm4 mutants exhibited decreased antioxidant enzyme activities and increased accumulation of reactive oxygen species. Microarray analysis indicated that a great proportion of genes affected by rdm4 overlapped with those affected by CBF2 and CBF3 in Arabidopsis. Chromatin immunoprecipitation (ChIP) results suggested that RDM4 is important for Pol II occupancy at the promoters of CBF genes but not the promoters of up-stream regulators of CBFs. Together, these data indicate that RDM4 acts as a component of a Pol II transcription complex that regulates CBF gene expression and cold stress resistance in Arabidopsis.
2016-06-30 | GSE63185 | GEO
Project description:The C-REPEAT-BINDING FACTOR (CBF) pathway has important roles in plant responses to cold stress. Previous research documented that constitutively expressed upstream transcription factors are activated by cold stress to induce the expression of CBF genes and the resulting CBF proteins trigger the expression of downstream cold responsive genes that confer freezing tolerance. In the present study, we found that dysfunction of RNA-DIRECTED DNA METHYLATION 4 (RDM4), which encodes a protein that associates with RNA polymerases Pol IV and Pol V as well as Pol II, and is required for RNA-directed DNA methylation (RdDM) and proper plant development in Arabidopsis, reduced chilling and freezing tolerance in Arabidopsis as evidenced by decreased survival and increased electrolyte leakage under cold stress conditions. CBFs and CBF regulon genes were down-regulated in rdm4 but not nrpe1 (the largest subunit of PolV) mutant plants, suggesting that the role of RDM4 in cold stress responses is independent of the RdDM pathway. Overexpression of RDM4 increased the expression of CBFs and CBF regulon genes and decreased cold-induced membrane injury. The rdm4 mutants exhibited decreased antioxidant enzyme activities and increased accumulation of reactive oxygen species. Microarray analysis indicated that a great proportion of genes affected by rdm4 overlapped with those affected by CBF2 and CBF3 in Arabidopsis. Chromatin immunoprecipitation (ChIP) results suggested that RDM4 is important for Pol II occupancy at the promoters of CBF genes but not the promoters of up-stream regulators of CBFs. Together, these data indicate that RDM4 acts as a component of a Pol II transcription complex that regulates CBF gene expression and cold stress resistance in Arabidopsis.
2016-06-30 | GSE63184 | GEO