Project description:The circadian clock represents a critical regulatory network, which allows plants to anticipate environmental changes as inputs and promote plant survival by regulating various physiological outputs. Here, we examine the function of the clock-regulated transcription factor, CYCLING DOF FACTOR 6 (CDF6), during cold stress in Arabidopsis thaliana. We found that the clock gates CDF6 transcript accumulation in the vasculature during cold stress. CDF6 mis-expression results in an altered flowering phenotype during both ambient and cold stress. A genome-wide transcriptome analysis links CDF6 to genes associated with flowering and seed germination during cold and ambient temperatures, respectively. Analysis of key floral regulators indicates that CDF6 alters flowering during cold stress by repressing photoperiodic flowering components, FLOWERING LOCUS T (FT), CONSTANS (CO), and BROTHER OF FT (BFT). Gene ontology enrichment further suggests that CDF6 regulates circadian and developmental associated genes. These results provide insight into how the clock-controlled CDF6 modulates plant development during moderate cold stress.
Project description:Most higher organisms, including plants and animals, have developed a time-keeping mechanism that allows them to anticipate daily fluctuations of environmental parameters such as light and temperature. This circadian clock efficiently coordinates plant growth and metabolism with respect to time-of-day by producing self-sustained rhythms of gene expression with an approximately 24-hour period. The importance of these rhythms has in fact been demonstrated in both phytoplankton and higher plants: organisms that have an internal clock period matched to the external environment possess a competitive advantage over those that do not. We used microarrays to identify circadian-regulated genes of Arabidopsis thaliana to elucidate how the clock provides an adaptive advantage by understanding how the clock regulates outputs and determining which pathways and processes may be under circadian control. Experiment Overall Design: Groups of Arabidopsis seedlings were grown in light/dark cycles for 7 d before, transferred to constant light, and after 24 h in constant light 12 samples were harvested at 4-h intervals over the next 44 h for RNA extraction and hybridization on Affymetrix microarrays.
Project description:Most higher organisms, including plants and animals, have developed a time-keeping mechanism that allows them to anticipate daily fluctuations of environmental parameters such as light and temperature. This circadian clock efficiently coordinates plant growth and metabolism with respect to time-of-day by producing self-sustained rhythms of gene expression with an approximately 24-hour period. The importance of these rhythms has in fact been demonstrated in both phytoplankton and higher plants: organisms that have an internal clock period matched to the external environment possess a competitive advantage over those that do not. We used microarrays to identify circadian-regulated genes of Arabidopsis thaliana to elucidate how the clock provides an adaptive advantage by understanding how the clock regulates outputs and determining which pathways and processes may be under circadian control. Keywords: time course
Project description:Broadly expressed transcriptions factors (TFs) control tissue-specific programs of gene expression through interactions with local TF networks. Prime examples are the circadian clock TFs CLOCK (CLK) and CYCLE (CYC or BMAL1): while they control a core transcriptional circuit throughout animal bodies, downstream clock target genes and circadian physiology are tissue-specific. Here, we use ChIP-seq to determine the regulatory targets of Drosophila CLK and CYC, which we epitope-tagged by homologous recombination. Both TFs have distinct binding sites in heads versus bodies, suggesting that they directly control tissue-specific downstream target genes. Analysis of these context-specific binding sites revealed distinct sequence motifs for putative clock partner factors, including a motif for the GATA factor SERPENT (SRP). SRP indeed synergistically enhances CLK/CYC-mediated activity of a cis-regulatory region bound by CLK/CYC specifically in bodies. These results reveal how universal clock circuits can generate tissue-specific outputs and demonstrate an approach to dissect regulatory interactions more generally. We sequenced ChIP and input samples, as well as M-bM-^@M-^\mockM-bM-^@M-^] samples for which we performed ChIP with the V5 antibody from wildtype w- flies (not carrying the V5 tag) for two independent biological replicates each, summing to 24 libraries in total.
Project description:A key function for RNA-binding proteins in orchestrating plant development and environmental responses is well established. However, the lack of a genome-wide view on their in vivo binding targets and binding landscapes represents a gap in understanding the mode of action of plant RNA-binding proteins. Here, we conducted RNA Immunoprecipitation (RIP-seq) for genome-wide determining the binding repertoire of the circadian clock-regulated Arabidopsis thaliana glycine-rich RNA-binding protein AtGRP7.
Project description:A key function for RNA-binding proteins in orchestrating plant development and environmental responses is well established. However, the lack of a genome-wide view on their in vivo regulatory landscapes represents a gap in understanding the mode of action of plant RNA-binding proteins. Here, we conducted RNAseq to determine the genome-wide regulation repertoire of the circadian clock-regulated Arabidopsis thaliana glycine-rich RNA-binding protein AtGRP7.
Project description:In many organisms, the circadian clock is composed of functionally coupled morning and evening oscillators that regulate the bouts of dawn and dusk activity. In Arabidopsis, oscillator coupling relies on a core loop in which the evening oscillator component TOC1 was proposed to activate a subset of morning-expressed oscillator genes. Our systems-biological approach overturns the current view of the Arabidopsis circadian clock showing that TOC1 does not function as an activator but as a timely-controlled general repressor of morning and evening oscillator components. Repression occurs through rhythmic binding to the promoters of all oscillator genes, suggesting a previously unexpected direct connection between the morning and evening loops.
Project description:In many organisms, the circadian clock is composed of functionally coupled morning and evening oscillators that regulate the bouts of dawn and dusk activity. In Arabidopsis, oscillator coupling relies on a core loop in which the evening oscillator component TOC1 was proposed to activate a subset of morning-expressed oscillator genes. Our systems-biological approach overturns the current view of the Arabidopsis circadian clock showing that TOC1 does not function as an activator but as a timely-controlled general repressor of morning and evening oscillator components. Repression occurs through rhythmic binding to the promoters of all oscillator genes, suggesting a previously unexpected direct connection between the morning and evening loops. Examination of TOC1 genome-wide binding using TOC1 Minigene (TMG) seedlings expressing the genomic fragment of TOC1 fused to the Yellow Fluorescent Protein in a toc1-2 mutant background (TMG-YFP/toc1-2 seedlings) grown under LD cycles (12h light:12h dark).