Project description:St (common potato) is a freezing sensitive species unable to cold acclimate. The close wild relative Sc is freezing tolerant and able to cold acclimate. Here we compare the cold transcriptome of these two species with different levels of freezing tolerance. We also identify the putative CBF regulons by comparing the transcriptomes of wild type plants with that of 35S::AtCBF3 transgenic lines in both species.
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: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: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:Arabidopsis thaliana and Eutrema salsugineum show the ability to cold acclimate. However, the degree of freezing tolerance depends in both cases on the accession. To elucidate the transcriptional basis of this differencial freezing tolerance, we performed where we grew plants under control conditions (20°C/18°C day/night) or under cold conditions (additional 4°C for 2 weeks). Rosettes were harvested from non-acclimated and cold acclimated plants for RNA isolation. Expression patterns were compared between treatments, accessions and species.
Project description:Cold temperatures are a threat to temperate plants, and Arabidopsis thaliana has acquired an adaptive gene expression network controlled by CBF transcription factors. The CBFs are sufficient to enable plants to survive otherwise lethal subzero temperatures. Constitutive CBF expression causes delayed flowering and stunted growth, and plants have evolved the ability to restrict CBF expression to occur only in the cold. This allows plants to anticipate likely freezing events and selectively deploy cold tolerance. The mechanism by which cold stress is sensed is however unknown. Here we show that protein translation rates in plants are proportional to temperature, and reduced translation rates trigger a rise in intracellular free calcium that activates the CAMTA transcription factors, and these directly activate cold-induced gene expression.
Project description:Overexpression of a grapevine C-repeat binding factor (CBF) gene, VvCBF4 in cv. “Freedom” was found to improve freezing survival in non-cold-acclimated vines. To understand the mechanistic basis of VvCBF4 transgene action, a transgenic line (‘9-12’) was genotyped using microarray-based mRNA expression profiling.
Project description:Improvement of freezing tolerance of red clover (Trifolium pratense L.) would increase its persistence under cold climate. In this study, we assessed the freezing tolerance and compared the proteome composition of non-acclimated and cold-acclimated plants of two initial cultivars of red clover: Endure (E-TF0) and Christie (C-TF0) and of populations issued from these cultivars after three (TF3) and four (TF4) cycles of phenotypic recurrent selection for superior freezing tolerance. Through this approach, we wanted to identify proteins that are associated with the improvement of freezing tolerance in red clover. Recurrent selection performed indoor is an effective approach to improve the freezing tolerance of red clover. Significant improvement of freezing tolerance by recurrent selection was associated with differential accumulation of a small number of cold-regulated proteins that may play an important role in the determination of the level of freezing tolerance.