ABSTRACT: RNA-DIRECTED DNA METHYLATION 4 modulates cold stress resistance in Arabidopsis through the C-REPEAT-BINDING FACTOR-mediated pathway [Agilent]
Project description:RNA-DIRECTED DNA METHYLATION 4 modulates cold stress resistance in Arabidopsis through the C-REPEAT-BINDING FACTOR-mediated pathway
Project description:RNA-DIRECTED DNA METHYLATION 4 modulates cold stress resistance in Arabidopsis through the C-REPEAT-BINDING FACTOR-mediated pathway [Affymetrix]
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.
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.
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.
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.
Project description:Cell water permeability and cell wall properties are critical to survival of plant cells during freezing, however the underlying molecular mechanisms remain elusive. Here, we report that a specifically cold-induced nuclear protein, Tolerant to Chilling and Freezing 1 (TCF1), interacts with histones H3 and H4, and associates with chromatin containing a target gene, BLUE-COPPER-BINDING PROTEIN (BCB), encoding a glycosylphosphatidylinositol-anchored protein that regulates lignin biosynthesis. Loss of TCF1 function leads to reduced BCB transcription through affecting H3K4me2 and H3K27me3 levels within the BCB gene, resulting in reduced lignin content and enhanced freezing tolerance. Furthermore, plants with knocked-down BCB expression (amiRNA-BCB) under cold acclimation had reduced lignin accumulation, and increased freezing tolerance. The pal1pal2 double mutant (lignin content reduced by 30% compared with WT) also showed the freezing tolerant phenotype, and TCF1 and BCB act upstream of PALs to regulate lignin content. In addition, TCF1 acts independently of the CBF (C-repeat binding factor) pathway. Our findings delineate a novel molecular pathway linking the TCF1-mediated cold-specific transcriptional program to lignin biosynthesis, thus achieving cell wall remodeling with increased water permeability and consequent freezing tolerance. Total RNA of three week old Arabidopsis seedlings was extracted using the TRIZOL Reagent according to the manufacturer's instructions. Gene-expression profiling was performed for each pooling RNA sample separately on the GeneChip at CapitalBio Corporation (Beijing, China).
Project description:Brassinosteroids (BRs) are growth-promoting plant hormones that play a role in abiotic stress responses, but molecular modes that enable this activity remain largely unknown. Here we show that BRs participate in the regulation of freezing tolerance. BR signaling-defective mutants of Arabidopsis thaliana were hypersensitive to freezing before and after cold acclimation. The constitutive activation of BR signaling, in contrast, enhanced freezing resistance. Evidence is provided that the BR-controlled basic helix–loop–helix transcription factor CESTA (CES) can contribute to the constitutive expression of the C-REPEAT/DEHYDRATION-RESPONSIVE ELEMENT BINDING FACTOR (CBF) transcriptional regulators that control cold responsive (COR) gene expression. In addition, CBF-independent classes of BR-regulated COR genes are identified that are regulated in a BR- and CES-dependent manner during cold acclimation. A model is presented in which BRs govern different cold-responsive transcriptional cascades through the posttranslational modification of CES and redundantly acting factors. This contributes to the basal resistance against freezing stress, but also to the further improvement of this resistance through cold acclimation. We used microarray data to investigate the contribution of different pathways to cold tolerance of Arabidopsis thaliana .
Project description:To understand mRNA expression pattern during cold acclimation and deacclimation, transcriptional profiling of cold acclimation and deacclimation-treated plants were analyzed using Agilent-015059 Arabidopsis 3 Oligo Microarray 4x44K G2519F.
Project description:Transcriptional gene silencing controls transposons and other repetitive elements through RNA-directed DNA methylation (RdDM) and heterochromatin formation. A key component of the Arabidopsis RdDM pathway is ARGONAUTE4 (AGO4), which associates with sizs to mediate DNA methylation. Here, we show that AGO4 preferentially targets transposable elements embedded within promoters of protein-coding genes. This pattern of AGO4 binding cannot be simply explained by the sequences of AGO4-bound siRNAs; instead, AGO4 binding to specific gene promoters is also mediated by long non-coding RNAs (lncRNAs) produced by RNA polymerase V. lncRNA-mediated AGO4 binding to gene promoters directs asymmetric DNA methylation to these genomic regions and is involved in regulating the expression of targeted genes. Finally, AGO4 binding overlaps sites of DNA methylation affected by the biotic stress response. Based on these findings, we propose that the targets of AGO4-directed RdDM are regulatory units responsible for controlling gene expression under specific environmental conditions. ChIP-seq experiments using AGO4 antibody of WT (Col-0) and ago4 or nrpe1 mutant plants of Arabidopsis thaliana