Unknown,Transcriptomics,Genomics,Proteomics

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Physiological, biochemical and genome-wide transcriptional analysis reveals that elevated CO2 mitigates the impact of combined heat wave and drought stress in Arabidopsis thaliana at multiple organizational levels

ABSTRACT: Genome-wide transcriptional profiling of Arabidopsis thaliana to a combination of heatwave and drought under ambient and elevated CO2. Goal of this study was elucidate the transcriptional responses to a combination of heat wave and drought, and to see how these responses are modifed under future climate (high) CO2. Climate changes increasingly threaten plant growth and productivity. Such changes are complex and involve multiple environmental factors, including rising CO2 levels and climate extreme events. As the molecular and physiological mechanisms underlying plant responses to realistic future climate extreme conditions are still poorly understood, a multiple organizational level-analysis (i.e. eco-physiological, biochemical and transcriptional) was performed, using Arabidopsis exposed to incremental heat wave and water deficit under elevated CO2.The climate extreme resulted in biomass reduction, photosynthesis inhibition, and considerable increases in stress parameters. Photosynthesis was a major target as demonstrated at the physiological and transcriptional levels. In contrast, the climate extreme treatment induced a protective effect on oxidative membrane damage, most likely as a result of strongly increased lipophilic antioxidants and membrane-protecting enzymes. Elevated CO2 significantly mitigated the negative impact of a combined heat and drought, as apparent in biomass reduction, photosynthesis inhibition, chlorophyll fluorescence decline, H2O2 production and protein oxidation. Analysis of enzymatic and molecular antioxidants revealed that the stress-mitigating CO2 effect operates through up-regulation of antioxidant defense metabolism, as well as by reduced photorespiration resulting in lowered oxidative pressure. Therefore, exposure to future climate extreme episodes will negatively impact plant growth and production, but elevated CO2 is likely to mitigate this effect. Transcriptome analysis was performed by Agilent Arabidopsis (V4) 4x44K platform which represented all known genes in the Arabidopsisgenome. Experiments were performed using a modified loop design (Knapen et al., 2009). This design consisted of total 8 arrays; sample from each treatment was labelled once and has 4 biological replicates, two of which were labelled in red and two in green

ORGANISM(S): Arabidopsis thaliana

SUBMITTER: Han Asard

PROVIDER: E-GEOD-57035 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:This study compared the photosynthetic performance and the global gene expression of the winter hardy wheat Triticum aestivum cv Norstar grown under non-acclimated (NA) or cold-acclimated (CA) condition at either ambient CO2 or elevated CO2 (EC). CA Norstar maintained comparable light saturated and CO2 saturated rates of photosynthesis but lower quantum requirements for photosystem II and non photochemical quenching relative to NA plants even at EC. Neither NA nor CA plants were sensitive to feedback inhibition of photosynthesis at EC. Global gene expression using microarray combined with bioinformatics analysis revealed that genes affected by EC were 3 times higher in NA (1022 genes) compared to CA (372 genes) Norstar. The most striking effect was the down-regulation of genes involved in the plant defense responses in NA Norstar. In contrast, cold acclimation reversed this down regulation due to the cold induction of genes involved in plant pathogenesis resistance, and cellular and chloroplast protection. These results suggest that EC have less impact on plant performance and productivity in cold adapted winter hardy plants in the northern climates compared to warmer environments. Selection for cereal cultivars with constitutively higher expression of biotic stress defense genes may be necessary under EC during the warm growth period and in warmer climates. Twelve replicate pots with 3 plants per pot were grown at either NA or CA conditions at either ambient or EC. To minimize any possible chamber effects, the 12 replicate pots at each growth condition were distributed between two growth chambers. A total of 3 biological replicates for each condition were used for microarray analyses. Each biological replicate sample was obtained by pooling three whole fully expanded 3rd leaves from different plants harvested randomly. The different biological samples of Norstar winter wheat leaves were ground in dry ice to fine powder and total RNA was extracted with trizol (Invitrogen, Burlington, ON, CA). Total RNA was cleaned using RNeasy plant mini kit (Qiagen) and integrity was determined on agarose gel and on a bioanalyser (Agilent 2100). Synthesized cDNAs were transcribed to cRNAs with the 3M-bM-^@M-^YIVT labelling kit (Santa Clara, CA, USA) and hybridized to the Affymetrix wheat genome array (Santa Clara, Ca, USA) at the McGill University and GM-CM-)nome QuM-CM-)bec Innovation Centre (Montreal, Qc, CA). The experimental design consisted of three biological replicates for each of the four growth conditions, 1: Non-acclimated (NA) at ambient CO2 (AC) (NAAC); 2: Cold-acclimated (CA) at ambient CO2 (AC) (CAAC); 3: Non-acclimated (NA) at elevated CO2 (EC) (NAEC); 4: Cold-acclimated (CA) at elevated CO2 (EC) (CAEC). Thus, a total of 3 biological samples from each of the 4 growth conditions described above were used for hybridizations.

Project description:We were awarded a BBSRC grant about a year ago to undertake some affymetrix gene chip profiling of light and CO2 systemic signalling in Arabidopsis. The design of the proposed experiment is given below and the appropriate funding has been provided by the BBSRC. The aim of the project is to identify the temporal profile of those genes that respond to light and CO2 systemic signals in developing leaves. Moreover, as thes two signals have opposing effects on leaf development to ascertain whether they involve similar or parallel signalling pathways. The experiment is to examine the effect of exposing mature leaves to high CO2 or low light or both on the gene expression profile of developing leaves. We already have data for maize that changes in gene expression profile occur within 4h and that there are a variety of temporal responses that differ between individual gene transcripts. We have also demonstrated that Arabidopsis leaf development is altered by these systemmic signals and that lesions in the jasmonate and ethylene signalling pathways block these responses. Our experimental design is shown below:; We have 4 treatments and 7 timepoints. (0, 2, 4, 12, 24, 48, 96 h); We would sample from 5 individual plants that would be pooled for each RNA preparation. This would require 28 chips and this would include extra replication of the 0 time-point control (deemed by many as nessary). Experimental details:; All plants were germinated for 7 days under the following conditions:; Humax multi-purpose compost, ambient carbon dioxide (370 ppm) and ambient light (250 Âµmol/m/s), constant temperature of 20Â°C and a 10 h photoperiod (8 am until 6 pm). After a week the the seedlings were potted up into 104-cell plug trays for a further 2 weeks and then potted up into 10 cm pots and the bottom part of the signalling cuvette system attached (see Lake et al., Nature 10th May 2001 Vol. 411, pp 154). Twenty four, 4 week old plants, then had the top part of the signalling system attached, trapping leaf insertions 5-13. Humidified, ambient air was passed through them at 500 mls/min via an oil-free air compressor. The three target leaves (19-21) were then marked with non-toxic, acrylic paint. After a 24 h period (the plants were sealed into the cuvettes from 10 am until 10am) of adjustment, the experiment was started by harvesting the target leaves from 4 plants and immediately freezing the tissue in liquid nitrogen to give the 0 h sample before RNA extraction. The remaining 20 plants were divided into 4 groups of five and given one of the following treatments:; Ambient carbon dioxide/ambient light (Control) (A); Elevated carbon dioxide (750 ppm)/ambient light (E); Ambient carbon dioxide/low light (50 Âµmol/m/s) (AS); Elevated carbon dioxide/low light (ES); - For the Elevated CO2, elevated CO2 was pumped in using a CT room next door set to same temperature but with a CO2 cylinder inside and the same pump as used in the ambient room to supply the elevated CO2 laden, humidified air into the signalling room using rubber tubing. - Shade treatment consisted of neutral density filter (Cat. 210 0.6ND, Lee Filters) that had a hole cut in the middle to allow the middle developing leaves to grow through. A timecourse of 2, 4, 12, 24, 48 and 96 h were carried out each using a batch of 24 plants. This whole process was repeated with another batch of 24 plants at the same developmental stage to give a 2, 4, 12, 24, 48 and 96 hour sample from each of the four treatments. The whole timecourse was then repeated 4 times. For the mature leaves:; We had 8 chips left over so we devised this little experiment to assess the gene changes that were occurring in the enclosed, treated, mature leaves that were signalling the environment to the young developing leaves. Experimenter name = Simon Coupe; Experimenter phone = 0114 222 4115; Experimenter fax = 0114 222 0002; Experimenter institute = University of Sheffield; Experimenter address = Animal and Plant Sciences; Experimenter address = University of Sheffield; Experimenter address = Western Bank; Experimenter address = Sheffield; Experimenter zip/postal_code = S10 2TN; Experimenter country = UK Experiment Overall Design: 8 samples were used in this experiment

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Physiological, biochemical and genome-wide transcriptional analysis reveals that elevated CO2 mitigates the impact of combined heat wave and drought stress in Arabidopsis thaliana at multiple organizational levels

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