Project description:Transcriptional profiling of Arabidopsis dark-induced senescence comparing wild type (Col-0) with pif quadruple (pif1/3/4/5) mutant. After synchronized germination, the plants were grown under continuous white light for 7 days and transferred to darkness for 2 days to induce senescence. Goal was to determine the effect of PIFs on transcriptomic regulation during dark-induced senescence.
Project description:A network model has been generated that describes the immediate gene expression cascade surrounding three similar but distinct NAC transcription factors that have roles to play in leaf senescence and in many stress responses in Arabidopsis. ANAC019, ANAC055 and ANAC072 belong to the same clade of NAC domain genes and have overlapping expression patterns. A combination of promoter DNA/protein interactions identified using yeast 1 hybrid analysis and modeling using gene expression time course data has been used to predict the regulatory network upstream of these genes. Similarities and divergence in regulation during a variety of stress responses are predicted by different combinations of upstream transcription factors binding and also by the modeling. Mutant analysis with potential upstream genes was used to test and confirm some of the predicted interactions.. Gene expression measurements in mutants of ANAC019 and ANAC055 at different times during leaf senescence have shown a distinctly different role for each of these genes. To assess mutant response to Dark Induced Senescence (DIS), leaf5 from transplanted rosettes, subjected to dark conditions, from Col-0, myb2 (genotype IM24) and myb108 (genotype BOS1) knockout plants, were photographically assessed for red/green ratio. When the average ratio for Col-0 samples was >0.8, leaf 5 for Col-0, myb2 and myb108 lines was harvested (4 biological replicates). The same sampling procedure was then performed on consecutive days to sample as senescence progressed. Analysis of expression differences between Col-0 and myb2 and Col-0 and myb108 under each condition, using dye swaps, was performed using the R Bioconductor package limmaGUI (Wettenhall and Smyth, 2004).
Project description:Detoxification of chlorophyll during leaf senescence in higher plants is a complex and tightly regulated process. It aims at opening the chlorophyll porphyrin ring to produce non-photoreactive degradation products, termed phyllobilins, which are stored in the vacuole. Here we are describing the influence on the transcriptome of dark-induced senescing leaf of the removal of three key enzymes of the PAO/phyllobilin pathway (namely: PAO, PPH and NYE/SGR).
Project description:Transcriptional profiling of Arabidopsis dark-induced senescence comparing wild type (Col-0) with pif quadruple (pif1/3/4/5) mutant. After synchronized germination, the plants were grown under continuous white light for 7 days and transferred to darkness for 2 days to induce senescence. Goal was to determine the effect of PIFs on transcriptomic regulation during dark-induced senescence. Two-condition experiment, wild type vs. pif quadruple mutant. Biological replicates: 3 wild type replicates, 3 mutant replicates.
Project description:This study profiles transcriptomic changes of Arabidopsis thaliana Col-0 in response to submergence. This dataset includes CEL files, RMA signal values and MAS5 P/M/A calls from total mRNA populations of plants at 9 to 10 leaf rosette stage. Biological replicates of root and shoot tissues were harvested after 7 h and 24 h of submergence in darkness along with corresponding non-submerged dark controls. To characterize the dark response, non-submerged light controls plants were harvested at the 0 h time point. Quantitative profiling of cellular mRNAs was accomplished with the Affymetrix ATH1 platform. Changes in the transcriptome in response to submergence and early darkness were evaluated, and the data led to identification of genes co-regulated at the conditional and organ-specific level.
Project description:Leaf senescence can be triggered by jasmonic acid (JA) and darkness. There are scattered reports about JA and dark-induced senescence, respectively. While the precise regulatory mechanisms that integrate these two factors to initiate and regulate leaf senescence have not been identified. Here, we report a transcriptional regulating module centered on novel WRKY transcription factor that is responsible for both JA and dark-induced leaf senescence in tomato. The expression levels of SlWRKY37 together with the master transcription factor in JA signaling SlMYC2 could be significantly induced by both MeJA and dark treatments. SlMYC2 directly binds to the promoter of SlWRKY37 to active its expression. Knock out of SlWRKY37 inhibited JA and dark-induced leaf senescence. Transcriptome analysis revealed 1312 differentially expressed genes between slwrky37-CR and SlWRKY37-OE, including genes involved in JA synthesis as well as several senescence-associated genes (SAGs). We characterized SlWRKY53 and SlSGR1 as direct transcriptional targets of SlWRKY37 to regulate leaf senescence. Moreover, SlWRKY37 interacts with SlVQ7 protein in vivo and the interaction enhances its binding ability to the promoters and transcriptional activation to downstream target genes. In addition, SlWRKY37 is phosphorylated at the post-translational level. Phosphorylation of SlWRKY37 is essential for its protein interaction and transcriptional activation, indicating phosphorylation modification has a great effect on the function of SlWRKY37 protein. Our study reveals the physiological and molecular functions of SlWRKY37 in leaf senescence and offered a target gene to retard leaf yellowing by reducing the sensitivity to internal and external senescence signal such as JA and darkness.
Project description:Nutrient remobilization during leaf senescence nourishes the growing plant. Understanding the regulation of this process is essential for reducing our dependence on nitrogen fertilizers and increasing agricultural sustainability. Our lab is interested in chromatin changes that accompany the transition to leaf senescence. Previously, darker green leaves were reported for Arabidopsis thaliana hac1 mutants, defective in a gene encoding a histone acetyltransferase in the CREB-binding protein family. Here, we show that two Arabidopsis hac1 alleles display delayed age-related developmental senescence, but have normal dark-induced senescence. Using a combination of ChIP-seq for H3K9ac and RNA-seq for gene expression, we identified 44 potential HAC1 targets during age-related developmental senescence. Genetic analysis demonstrated that one of these potential targets, ERF022, is a positive regulator of leaf senescence. ERF022 is regulated additively by HAC1 and MED25, suggesting MED25 may recruit HAC1 to the ERF022 promoter to increase its expression in older leaves.