Project description:The stability of mRNA is an important determinant of its abundance and, consequently, protein production. There has been extensive research on the pathways governing mRNA stability and translation, however, it is unclear the extent to which these processes are modulated by environmental conditions. We previously modelled rapid recovery gene down-regulation (RRGD) following light stress in Arabidopsis thaliana (Arabidopsis) using mathematical calculations to account for transcription in order to predict half-lives and led to the hypothesis of recovery-specific transcript destabilisation. Here, we test this hypothesis by quantifying changes in transcription, mRNA stability, and translation in leaves of mature Arabidopsis undergoing light stress and recovery and investigate processes regulating transcript abundance and fate. Compared to juvenile plants from prior work, here we find that stability is altered for a range of transcripts that encode proteins involved in post-transcriptional processes in mature leaves. We also observe transcript destabilisation during light stress, followed by re-stabilisation upon recovery. Alongside this, we observe fast transcriptional shut-off in recovery that, when paired with transcript destabilisation, promotes rapid down-regulation of stress-induced genes. Translation was dynamic over the course of light stress and recovery, with substantial transcript-specific increases in polysome loading observed during late stress independently of total mRNA abundance. Taken together, we provide evidence for the combinatorial regulation of transcription, mRNA stability, and translation that occurs during light stress and recovery.
Project description:To understand plant adaptation to heat stress, gene expression profiles of Arabidopsis leaves under heat stress, during recovery and control condition were obtained using microarray. Microarray data listed responsible candidate genes for glycerolipid metabolism. Arabidopsis thaliana ecotype Columbia (Col-0) seeds were surface-sterilised and sown on an agar-solidified Murashige and Skoog medium. Plants were grown at 22ºC under a 16-h-light/8-h-dark cycle. Vegetative plants were subjected to high temperature for a day, then continued to be grown under normal condition for a day.
Project description:Plants acclimate to environmental fluctuations by transitory reconfigurations the homeostatic network. Primary studies suggested that transcriptome responses to deal with fluctuations in light intensity and temperature tend to reversibility after stress removal in the model plant Arabidopsis thaliana. To gain more insight into this pattern in the context of acclimation, RNA-Seq analysis were conducted in Arabidopsis thaliana after different abiotic stress treatments consisting in high light (HL), high humidity, drought, heat, cold and combinations among factors or after recovery periods. Our transcriptome study is in line of a general pattern wherby transcriptome changes in response to adverse environments are prone to return to the basal state during the de-acclimation phase.
Project description:To understand plant adaptation to heat stress, gene expression profiles of Arabidopsis leaves under heat stress, during recovery and control condition were obtained using microarray. Microarray data listed responsible candidate genes for glycerolipid metabolism.
Project description:In light of the changes in precipitation and soil water availability expected with climate change, understanding the mechanisms underlying plant responses to water deficit is essential. Toward that end we have conducted an integrative analysis of responses to drought stress in the perennial C4 grass and biofuel crop, Panicum virgatum (switchgrass). Responses to soil drying and re-watering were measured at transcriptional, physiological, and metabolomic levels. To assess the interaction of soil moisture with diel light:dark cycles, we profiled gene expression in drought and control treatments under pre-dawn and mid-day conditions. Soil drying resulted in reduced leaf water potential, gas exchange, and chlorophyll fluorescence along with differential expression of a large fraction of the transcriptome (37%). Many transcripts responded differently depending on time of day (e.g. up-regulation pre-dawn and down-regulation mid-day). Genes associated with C4 photosynthesis were down-regulated during drought, while C4 metabolic intermediates accumulated. Rapid changes in gene expression were observed during recovery from drought, along with increased water use efficiency and chlorophyll fluorescence. Our findings demonstrate that drought responsive gene expression depends strongly on time of day and that gene expression is extensively modified during the first few hours of drought recovery. Analysis of covariation in gene expression, metabolite abundance, and physiology among plants revealed non-linear relationships that suggest critical thresholds in drought stress responses. Future studies may benefit from evaluating these thresholds among diverse accessions of switchgrass and other C4 grasses. mRNA profiles of leaf tissue from clonal replicates at various time points during drydown and recovery were generated by deep sequencing 3' mRNA tags using SOLiD.
Project description:Arabidopsis (Arabidopsis thaliana) leaf was exposed to excess light for 30 min and 2 hours. Expression levels relative to low light (LL) were determined
Project description:Low oxygen stress dynamically regulates the translation of cellular mRNAs as a means of energy conservation in seedlings of Arabidopsis thaliana. Most of the highly hypoxia-induced mRNAs are recruited to polysomes and actively translated, whereas other cellular mRNAs become translationally inactive and are either targeted for stabilization or degradation. Here we identify the involvement of OLIGOURIDYLATE BINDING PROTEIN 1 (UBP1), a triple RNA Recognition Motif protein, in dynamic and reversible aggregation of translationally repressed mRNAs during hypoxia. Mutation or downregulation of UBP1C interferes with seedling establishment and reduces survival of low oxygen stress. By use of messenger ribonucleoprotein immunopurification, we show that UBP1C constitutively binds a subpopulation of mRNAs characterized by U-rich 3M-bM-^@M-^Y-untranslated regions under normoxic conditions. During hypoxia, UBP1C association with non-U-rich mRNAs is enhanced concomitant with its aggregation into microscopically visible cytoplasmic foci, referred to as UBP1 stress granules (SGs). This UBP1C-mRNA association occurs as global levels of protein synthesis decline. Upon reoxygenation, rapid UBP1 SG disaggregation coincides with the return of the stabilized mRNAs to polysomes. The mRNAs that are highly induced and translated during hypoxia largely circumvent UBP1C sequestration. Thus, UBP1 is established as a component of dynamically assembled cytoplasmic mRNPs that sequester mRNAs that are poorly translated during a transient low energy stress. Immunoprecipated RNA associated with Arabidopsis UBP1C (IP) was compared with total cellular RNA from light (L), mock dark (D), 2 h hypoxia, and 2 h hypoxia + 20 min reoxygenation treated samples with duplicate hybridizations to the Affymetrix ATH1 Genechip array.
Project description:SUMOylation, a post-translational protein modification, is dramatically upregulated and critically involved in heat stress response conservatively among species. Previous studies in Arabidopsis indicated that numerous chromatin associated proteins are SUMOylation substrates and most of heat-enhancing SUMOylation reactions occur in nucleus. However, the global functional connection between gene expression regulation and SUMOylation on chromatin is completely unknown in plant cells. Here we show a genome-wide relationship of chromatin-associated SUMOylation and transcription switches under room temperature, heat stress, and recovering conditions in Arabidopsis. The SUMO-associated chromatin sites, characterized via whole-genome ChIP-seq assays, are generally correlated with active chromatin markers. In response to heat stress, we found chromatin-associated SUMO signals increased at promoter-transcriptional start site regions and decreased in the gene bodies. Further RNA-seq analysis supported the role of chromatin-associated SUMOylation in activation of transcription during rapid responses to high temperature. Changing of SUMO signals on chromatin is correlated with upregulation of heat-responsive genes and downregulation of growth-related genes. Disruption of the SUMO ligase gene SIZ1 abolishes SUMO signals on chromatin and attenuates the rapid transcriptional responses to heat stress. Interestingly, the SUMO signal peaks are enriched in DNA elements recognized by distinguished groups of transcription factors under different temperature conditions. Collectively, our data provide evidence that SUMOylation on chromatin regulates transcription switches during development and heat stress response, improving our understanding on the precise roles of SUMOylation in plant cells.
Project description:Arabidopsis (Arabidopsis thaliana) leaf was exposed to excess light for 30 min and 2 hours or to 24 µM DBMIB for 30 min and 2 hours. Expression levels relative to low light (LL) were determined