RNA-seq of Arabidopsis lyrata ssp. lyrata leaves under thermal stress to compare gene expression patterns between acclimated and non-acclimated plants.
ABSTRACT: We aimed to understand the ecological and evolutionary implications of thermal acclimation. Seeds of 40 maternal plants of Arabidopsis lyrata ssp. lyrata of one population were collected at Saugatuck Dunes State Park, Michigan, USA. Plants were then raised in growth chambers under three acclimation treatments: frost, heat, or no acclimation (40 maternal families x 3 treatments x 3 replicates = 360 plants). At the end of the treatment period, one rosette leaf was collected for 16 individuals per treatment for a RNA-seq analysis. We compared gene expression patterns between acclimated and non-acclimated plants.
Project description:Heat acclimation (AC) allows its faster re-induction following its decline. Constitutively preserved euchromatin state in hsp70 promoter during acclimation decline/regain pushed forward the hypothesis that acclimation decline is a period of “dormant memory” involving molecular program including epigenetic controlled transcriptional regulation leading to heat acclimation mediated cytoprotective memory. We used microarray to uncover hallmark pathways in the induction of heat-acclimation-mediated memory, focusing on markers of epigenetic processes. Rats subjected to heat acclimation, deacclimation, reacclimation and untreated controls were used. We showed here that (i) AC2d provides the molecular switch for acclimation (ii) AC30 heart demonstrates qualitative adaptations (iii) specific molecular program encompassing up/down regulated gene during DeAC, of which epigenetic markers such as class A histones, chromatin modifiers and microRNA suggest epigenetic transcriptional regulation linked to acclimation memory (iv) constitutive upregulation of MAPK P38 module and targets as well as jak/stat and AKT associated pathways during DeAC imply its major role in this process. Noteworthy are players such as poly-(ADP-ribose)polymerase-1 (PARP1) and linker histones (histones H1 cluster in this process).
Project description:affy_sunflower_2011_02 - affy_sunflower_2011_02 - The early sowing constitutes an alternative strategy to avoid drought occurring during flowering and post-flowering periods and responsible for decrease in sunflower production. In French cropping system, early sowing is associated to low temperature period and frost during first development stages in sunflower. Knowledge about metabolism of frost acclimation must be performed to supply tools for breeding programs in sunflower. The aim of our experiment is to unravel the transcriptional regulation underpinning frost tolerance in sunflower-5 genotypes of sunflower were grown in a growth chamber 1 (23°C day/18°C night, 63% air humidity, 14 hours day photoperiod). At the stage of 6 leaves well-developed, 12 plants of each genotype were subjected to cold acclimation (+4°C during 2 days) in another growth chamber 2. Then, these plants were subjected to 2 nights at -3°C (frost treatment). Chlorophylle fluorescence, Osmotic potential, Relative electrolyte leakage were then determined in the following conditions : - 6th October on 6 plants X 5 genotypes from growth chamber 1 (C1) - 6th October on 6 plants X 5 genotypes from growth chamber 2 (S1) - 11th October on 6 plants X 5 genotypes from growth chamber 1 (C2) - 11th October on 6 plants X 5 genotypes from growth chamber 1 (S2) 12 arrays - SUNFLOWER; treated vs untreated comparison
Project description:Although significant work has been undertaken regarding the response of model and crop plants to heat shock during the acclimatory phase, few studies have examined the steady state response to the mild heat stress encountered in temperate agriculture. In the present work we therefore exposed tuberising potato plants to mildly elevated temperatures (30/20C), day/night) for up to five weeks and compared tuber yield, physiological and biochemical responses, and leaf and tuber metabolomes and transcriptomes with plants grown under optimal conditions (22/16C). Growth at elevated temperature reduced tuber yield despite an increase in net foliar photosynthesis. This was associated with major shifts in leaf and tuber metabolite profiles, a significant decrease in leaf glutathione redox state and decreased starch synthesis in tubers. Furthermore, growth at elevated temperature had a profound impact on leaf and tuber transcript expression with large numbers of transcripts displaying a rhythmic oscillation at the higher growth temperature. RT-PCR revealed perturbation in the expression of circadian clock transcripts including StSP6A, previously identified as a tuberisation signal. Our data indicate that potato plants grown at moderately elevated temperatures do not exhibit classic symptoms of abiotic stress but that tuber development responds via a diversity of biochemical and molecular signals. In this submission we are looking at gene expression changes with respect to both temperature and time, every 4h over a 24h period whereby diurnal changes may be apparent.
Project description:Systems responses of mature leaves from 4 reference cultivars of a larger collection of European potato cultivars (Solanum tuberosum L.) are investigated by metabolome profiling and RNA-Sequencing. The chosen reference cultivars, Milva, Alegria, Desiree, and Saturna, vary in ascending order in regard to drought tolerance. Systems analyses are based on 3 independent field trials and 3 paralleled greenhouse trials. Robust responses across all cultivars and conditions to natural seasonal drought stress comprise proline, raffinose, galactinol, arabitol, arabinonic acid, chlorogenic acid, and 102 transcripts which consist to a high proportion of heat shock proteins and genes with signaling or regulatory functions, such as a homolog of abscisic acid receptor PYL4. Constitutive differences of the tolerant cultivars, Desiree and Saturna, compared to the sensitive cultivars include arbutin (hydroquinone-beta-D-glucopyranoside), octopamine (p-hydroxyphenylethanolamine), ribitol and 248 differential transcripts. Many of these transcripts are disease related, receptor kinases, or regulatory genes, for example a homolog of the Arabidopsis FOUR LIPS MYB-regulator of stomatal cell proliferation. Functional enrichment analyses imply that heat stress is a major acclimation component of potato leaves to agronomical relevant drought stress. Enhanced leaf heat stress is a result of drought caused by loss of transpiration cooling. This effect and CO2-limitation are the main dilemmas of drought- or ABA-induced stomatal closure. Constitutive differences between tolerant and sensitive cultivars indicate partially synergistic interactions of drought and biotic stress responses. We suggest that drought tolerance of the potato reference cultivars may be caused by general resistance mechanisms which are part of previously selected pathogen tolerance. Transcriptome profiling by RNA-sequencing of 48 leaf samples from 4 potato cultivars grown under control or drought stress conditions in 6 independent experiments
Project description:We report the identification of a heat-stress mediated mRNA decay in arabidopsis that is mediated by the XRN4 exonuclease and LARP1 RNA-binding protein. mRNA population in WT and larp1 mutant at 20C or 15 min at 38C
Project description:Arabidopsis 5’-3’ exoribonuclease, AtXRN4, a homolog of yeast Xrn1p, functions in degradation of uncapped RNAs after de-capping step. While Xrn1p-dependent on plant XRN4’s targets for degradation is still limited. For understanding biological function of AtXRN4, we tested survivability of atxrn4 mutants under heat stress. Our results showed that atxrn4 mutants increased survival rate under short-term degradation is a main mRNA decay in yeast, knowledge heat stress compared with WT plants. Our microarray and mRNA decay assay showed that loss of AtXRN4 function caused reduction of mRNA degradation of heat shock factor A2 (HSFA2) and ethylene response factor 1 (ERF1). HSFA2 has been known as a key regulator in heat acclimation, was found as a target for AtXRN4 for degradation at non-stress condition. Heat stress applied on atxrn4-3 hsfa2 double mutant severely lacked heat tolerance phenotype of atxrn4 mutant. These results suggest that AtXRN4-mediated mRNA degradation linked to suppress heat acclimation. In the study here, 2 week-old WT and atxrn4-3 mutant plants were exposure to non-stress (22oC) and heat-stress (37oC, 1 h). Custom microarray was applied to acquire expression profile of 32788 Arabidopsis genes. 3 biological repeats of WT (non-stress), WT(heat stress), atxrn4-3 (non-stress) and atxrn4-3 (heat stress) were used for microarray analysis
Project description:To identify the respective roles of light and ROS in the photoinhibition process and detect a possible light-driven tolerance to oxidative stress, we compared the transcriptomic responses of Synechococcus sp. WH7803 acclimated to low (LL) or high light (HL) to oxidative stress, induced by hydrogen peroxide (H202) or methylviologen (MV). Cultures were acclimated during many generations to continuous low light (LL, 18 ?mol photons m-2 s-1, hereafter LL cells) and high light (HL, 250 ?mol photons m-2 s-1, hereafter HL cells) provided by Sylvania Daylight 58W/154 fluorescent bulbs. For all stress experiments performed in this study, exponentially growing cultures (1 to 3 x 107 cells mL-1), were split into subcultures and submitted to oxidative stress by addition of H2O2 or MV and harvested when PSII quantum yield fell to half of the initial value. For H2O2 experiments, this level of PSII photoinactivation was reached 2 h after submitting LL and HL cultures to 750 µM and 25 µM respectively. Because of the large divergence in dose and kinetics responses to MV between LL- and HL cells, it was not possible to find MV concentrations leading to 50 % decrease of quantum yield at the same time for both light acclimations. Thus, array analyses for MV were performed on HL and LL cultures incubated at the same MV concentration (50 µM) but harvested once PSII quantum yield was halved, i.e. after 1 and 3.5 h of stress respectively. All hybridizations were performed on 4 independent biological replicates and using as reference sample a pool of RNA from all samples investigated in this study. Pairwise comparison were performed to analyze the stress induced by either H2O2 or MV on both LL- and HL cultures (i.e. LL-Ct vs. LL+MV, LL-Ct vs. LL+H2O2, HL-Ct vs. HL+MV, HL-Ct vs. HL+H2O2) as well as to compare the steady state acclimation to different light conditions (i.e. LL-Ct vs. HL-Ct).
Project description:A common measure of heat resistance in Drosophila is the time it takes a fly to be knocked down by higher temperatures measured in a long knockdown tube or in small glass vials. This heat knockdown process involves gradual paralysis and non-responsiveness to stimuli, usually within half hour duration of constant heat exposure, and is ostensibly reversible upon return to lower temperatures, although there may be long-term fitness effects. Hardening for increased heat resistance requires exposure periods of up to 3 hours at temperatures ranging from 34C to 38C. The experiment was aimed at understanding the heat hardening process and samples were taken during the hardening period (15 minutes, 45 minutes, 1½ hours, 2¼ hours and 3 hours).
Project description:Stress acclimation is an effective mechanism that plants acquired for adaption to dynamic environmental conditions. After undergoing cold acclimation, plants become more tolerant to cold stress. In order to understand the mechanism of cold acclimation, we performed a systematic, comprehensive study of cold response and acclimation in Cassava (Manihot esculenta), a staple crop and major food source in the tropical regions of the world. We profiled mRNA genes and small-RNA species, using next generation sequencing, and performed an integrative analysis of the transcriptome and microRNAome of Cassava across the normal condition, a moderate cold stress at 14°C, a harsh stress at 4°C after cold acclimation at 14°C, and a cold shock from 24°C to 4°C. Two results from the analysis were striking. First, the moderate stress and cold shock, despite a difference of 10°C between the two, triggered comparable degrees of perturbation to the transcriptome; in contrary, further harsh stress after cold acclimation resulted in a much smaller degree of transcriptome variation. Second and more importantly, about two thirds of the up- or down-regulated genes after moderate stress reversed their expression to down- or up-regulation, respectively, under harsh stress after cold acclimation, resulting in a genome-wide rewiring of regulatory networks. MicroRNAs, which are key post-transcriptional gene regulators, were major players in this massive rewiring of genetic circuitry. Further, a function enrichment analysis of the perturbed genes revealed that cold acclimation helped the plant to develop immunity to further harsh stress by exclusively inducing genes with functions of nutrient reservoir; in contrast, many genes with functions of viral reproduction were induced by cold shock. Our study revealed, for the first time, the molecular basis of stress acclimation in plants, and shed lights on the role of microRNA gene regulation in cold response and acclimation in Euphorbia. Three organs/tissues (folded leaf, fully expanded leaf and roots) of Cassava cultivar SC124 harvested at 6h, 24h and 5d for three cold treatments of CA, CCA and CS, for gene expression profiling at the stages of initial response, secondary response, and functional adaption to cold stresses. Total RNA of each sample was isolated individually, and then pooled with an equal amount from each sample into one for profiling. As a result, four mRNA libraries and four small-RNA libraries, corresponding to the conditions of CA, CCA, CS and NC, were constructed.