Transcription profiling by array of Arabidopsis leaves exposed to excess light and DBMIB
ABSTRACT: 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
BACKGROUND: Salicylic acid is a critical signalling component in plant defence responses. In Arabidopsis, isochorismate synthase encoded by SID2 is essential for the biosynthesis of salicylic acid in response to biotic challenges. Recently, both the calmodulin binding protein CBP60g and its closest homolog, the non-calmodulin binding SARD1, have been shown to bind to the promoter region of SID2. Loss of both CBP60g and SARD1 severely impacts the plants ability to produce SA in response to bacter ...[more]
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
Project description:The effect of light during the development of freezing tolerance was studied in winter wheat (Triticum aestivum L. var. Mv Emese) and spring wheat variety Nadro. Ten-day-old plants were cold hardened at 5°C for 12 days either under normal (250 mmol m-2 s-1) or low light (20 mmol m-2 s-1) conditions. Samples of Emese (E) and Nadro (N) plants grown at 18°C under normal (NL) and low (LL) light fluences were compared to each other in a simple loop design and E-NL vs. E-LL; N-NL vs. N-LL; E-NL vs. NLL and E-LL vs. N-LL comparisons were made.
Project description:In most organisms biological processes are partitioned, or phased to specific times over the day through interactions between external cycles of temperature (thermocycles) and light (photocycles), and the endogenous circadian clock. This orchestration of biological activities is achieved in part through an underlying transcriptional network. To understand how thermocycles, photocycles and the circadian clock interact to control time of day specific transcript abundance in Arabidopsis thaliana, we conducted four diurnal and three circadian two-day time courses using Affymetrix GeneChips (ATH1). All time courses were carried out with seven-day-old seedlings grown on agar plates under thermocycles (HC, hot/cold) and/or photocycles (LD, light/dark), or continuous conditions (LL, continuous light; DD, continuous dark, HH, continuous hot). Whole seedlings (50-100), including roots, stems and leaves were collected every four hours and frozen in liquid nitrogen. The four time courses interrogating the interaction between thermocycles, photocycles and the circadian clock were carried out as two four-day time courses. Four-day time courses were divided into two days under diurnal conditions, and two days under circadian conditions of continuous light and temperature. Thermocycles of 12 hours at 22C (hot) and 12 hours at 12C (cold) were used in this study. The two time courses interrogating photoperiod were conducted under short days (8 hrs light and 16 hrs dark) or long days (16 hrs light and 8 hrs dark) under constant temperature. In addition, the photoperiod time courses were in the Landsberg erecta (ler) accession, in contrast to the other time courses that are in the Columbia (col) background. The final time course interrogated circadian rhythmicity in seedlings grown completely in the dark (etiolated). Dark grown seedlings were synchronized with thermocycles, and plants were sampled under the circadian conditions of continuous dark and temperature.
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:Transcriptional profiling of Arabidopsis thaliana Ler wildtype and eid3 (empfindlicher im dunkelroten Licht 3) mutant seedlings in darkness and 45 min after a red-light pulse. Arabidopsis thaliana Ler wildtype and eid3 mutant seedlings were grown on 1/2 MS Agar plates covered with filter paper for 4 days in darkness after induction of germination with 2 h red light. Samples were either treated with 2 min red light (30 µmol/m2s) or kept in darkness and harvested after additional 45 min in darkness. 3 biological replicas were used for each of the 4 experimental conditions.
Project description:Arabidopsis thaliana plants from the genotypes Col-0 and snrk2.2-2.3 (snrkD, double knock-out) were used. They were grown in a growth chamber for 5 weeks in short day (8/16 light/dark cycle) at 22 degrees, 150 umol*m2*s-1 (fluorescent lights) and 55% RH in 100-ml pots with Levingtons L2+S. On the day of the experiment, two hours after the lights turned on they were subjected to mild light stress (approx. 1500 umol*m-2*s-1, measured with a PAR light meter) for 30 min under an Isolight machine (white LED array), and immediately snap-frozen in liquid nitrogen. The outer leaves from four biological replicates were ground and RNA purified, and labelled RNA was produced with the Agilent Quick Amp kit. Labelled RNA was hybridized to Agilent Arabidopsis V4 microarray slides, and the fluorescence recorded with a Genepix scanner.
Project description:Arabidopsis thaliana plants from the genotypes Col-0 and ABA2OE (35S:ABA2 overexpressor in Col-0 background) were used. They were grown in a growth chamber for 5 weeks in short day (8/16 light/dark cycle) at 22 degrees, 150 umol*m2*s-1 (fluorescent lights) and 55% RH in 100-ml pots with Levington's L2+S. On the day of the experiment, two hours after the lights turned on they were subjected to mild light stress (approx. 1500 umol*m-2*s-1, measured with a PAR light meter) for 30 min under an Isolight machine (white LED array), and immediately snap-frozen in liquid nitrogen. The outer leaves from four biological replicates were ground and RNA purified, and labelled RNA was produced with the Agilent Quick Amp kit. Labelled RNA was hybridized to Agilent Arabidopsis V4 microarray slides, and the fluorescence recorded with a Genepix scanner.