Project description:We used the flu mutant of Arabidopsis to detail gene expression in response to singlet oxygen. The conditional flu mutant of Arabidopsis accumulates excess protochlorophyllide in the dark within chloroplast membranes that upon illumination acts as a photosensitizer and generates singlet oxygen. Immediately after the release of singlet oxygen mature flu plants stop growing, whereas seedlings bleach and die. Within the first 30 min after the release of singlet oxygen rapid changes in nuclear gene expression occur. Distinct sets of genes were activated that were different from those induced by other reactive oxygen species, superoxide or hydrogen peroxide. Experiment Overall Design: Arabidopsis thaliana rosette leaves were harvested after 30 min, 1h, and 2 h of reillumination following a 8h dark period for RNA extraction and hybridization on Affymetrix ATH1 microarrays. Plants were grown on soil for 3 weeks under continuous light at 90 mmol. m-2 . s-1. For each sample, the rosette leaves of five to six 3-week-old plants (before they start bolting) were collected for RNA extraction. Total RNAs from two separate biological experiments were pooled for the preparation of cDNA and the subsequent synthesis of biotin-labeled complementary RNA as recommended by Affymetrix.
Project description:We used microarrays to detail Arabidopsis gene expression in response to paraquat, a herbicide that acts as a terminal oxidant of photosystem I that in the light leads to the enhanced generation of superoxide and hydrogen peroxide inside plastids. Within a few hours after paraquat treatment changes in nuclear gene expression occur. Distinct sets of genes were activated that were different from those induced by another reactive oxygen species, singlet oxygen. Experiment Overall Design: Arabidopsis thaliana rosette leaves were harvested 1, 2, and 4 h after spraying either with a solution of 20 microM paraquat (methyl viologen, Sigma) in 0.1% Tween or with Tween alone for RNA extraction and hybridization on Affymetrix ATH1 microarrays. Plants were grown on soil for 3 weeks under continuous light at 90 mmol. m-2 . s-1. For each sample, the rosette leaves of five to six 3-week-old plants (before they start bolting) were collected for RNA extraction. Total RNAs from two separate biological experiments were pooled for the preparation of cDNA and the subsequent synthesis of biotin-labeled complementary RNA as recommended by Affymetrix.
Project description:We used the flu mutant of Arabidopsis to detail gene expression in response to singlet oxygen. The conditional flu mutant of Arabidopsis accumulates excess protochlorophyllide in the dark within chloroplast membranes that upon illumination acts as a photosensitizer and generates singlet oxygen. Immediately after the release of singlet oxygen mature flu plants stop growing, whereas seedlings bleach and die. Within the first 30 min after the release of singlet oxygen rapid changes in nuclear gene expression occur. Distinct sets of genes were activated that were different from those induced by other reactive oxygen species, superoxide or hydrogen peroxide. Keywords: Time course
Project description:The aim of this study was to analyze the impact of autotetraploidy on gene expression in Arabidopsis thaliana by comparing diploid versus tetraploid transcriptomes. In particular, this included the comparison of the transcriptome of different tetraploid A. thaliana ecotypes (Col-0 vs. Ler-0). The study was extended to address further aspects. One was the comparison of the transcriptomes in subsequent generations. This intended to obtain information on the genome wide stability of autotetraploid gene expression. Another line of work compared the transcriptomes of different diploid vs. tetraploid tissues. This aimed to investigate whether particular gene groups are specifically affected during the development of A. thaliana autotetraploids. Samples 1-8: Arabidopsis thaliana Col-0 tetraploid transcriptome. Transcriptional profiling and comparison of diploid vs. tetraploid Col-0 seedlings. The experiment was carried out with pedigree of independently generated and assessed tetraploid Col-0 lines. Samples 9-12: Arabidopsis thaliana Ler-0 tetraploid transcriptome. Transcriptional profiling and comparison of diploid vs. tetraploid Ler-0 seedlings. The experiment was carried out with pedigree of independently generated and assessed tetraploid Ler-0 lines. Samples 13-24: Arabidopsis thaliana Col-0 tetraploid transcriptome. Transcriptional profiling and comparison of diploid vs. tetraploid Col-0 leaves (6th - 8th). The experiment was carried out with pedigree of independently generated and assessed tetraploid Col-0 lines. Samples 25-32: Arabidopsis thaliana Ler-0 tetraploid transcriptome. Transcriptional profiling and comparison of diploid vs. tetraploid Ler-0 leaves (6th - 8th). The experiment was carried out with pedigree of independently generated and assessed tetraploid Ler-0 lines. Samples 33-36: Arabidopsis thaliana Ler-0 tetraploid transcriptome. Transcriptional profiling and comparison of tetraploid vs. tetraploid Ler-0 seedlings from the second (F2) and third (F3) generation after induction, respectively. The experiment was carried out with pedigree of independently generated and assessed tetraploid Ler-0 lines. Samples 37-40: Arabidopsis thaliana Col-0 tetraploid transcriptome. Transcriptional profiling and comparison of tetraploid vs. tetraploid Col-0 seedlings from the second (F2) and third (F3) generation after induction, respectively. The experiment was carried out with pedigree of independently generated and assessed tetraploid Col-0 lines. Samples 41-44: Arabidopsis thaliana Col-0/Ler-0 diploid transcriptome. Transcriptional profiling and comparison of diploid Col-0 vs. diploid Ler-0 seedlings. The experiment was carried out with pedigree of esrablished lines. Samples 45-48: Arabidopsis thaliana Col-0/Ler-0 tetraploid transcriptome. Transcriptional profiling and comparison of tetraploid Col-0 vs tetraploid Ler-0 seedlings. The experiment was carried out with pedigree of independently generated and assessed tetraploid Col-0 and Ler-0 lines.
Project description:We used the flu mutant of Arabidopsis and a transgenic line that overexpresses the thylakoid-bound ascorbate peroxidase (tAPX) to address the interactions between different reactive oxygen species (ROS) signaling pathways. The conditional flu mutant of Arabidopsis accumulates excess protochlorophyllide in the dark within chloroplast membranes that upon illumination acts as a photosensitizer and generates singlet oxygen (1O2). Immediately after the release of singlet oxygen rapid changes in nuclear gene expression occur. Distinct sets of genes were activated that were different from those induced by other reactive oxygen species, superoxide or hydrogen peroxide (H2O2), suggesting that different types of active oxygen species activate distinct signaling pathways. It was not known whether the pathways operate separately or interact with each other. We have addressed this problem by modulating noninvasively the level of H2O2 in plastids by means of a transgenic line that overexpresses the thylakoid-bound ascorbate peroxidase (tAPX, line 14/2 PMID: 15165186). In the flu mutant overexpressing tAPX, the expression of most of the nuclear genes that were rapidly activated after the release of 1O2 was significantly higher in flu plants overexpressing tAPX, whereas in wild-type plants, overexpression of tAPX had only a very minor impact on nuclear gene expression. The results suggest that H2O2 antagonizes the 1O2-mediated signaling of stress responses as seen in the flu mutant. This cross-talk between H2O2- and 1O2-dependent signaling pathways might contribute to the overall stability and robustness of wild-type plants exposed to adverse environmental stress conditions. Experiment Overall Design: Arabidopsis thaliana rosette leaves were harvested after 2 h of reillumination following a 8h dark period for RNA extraction and hybridization on Affymetrix ATH1 microarrays. The entire experiment was performed six times, providing independent biological replicates. For each of the six experiments, all four lines, wild-type, thylakoidal ascorbate peroxidase overexpressor (over tAPX, line 14/2), flu mutant and flu plants overexpressing thylakoidal ascorbate peroxidase were grown for 3 weeks under continuous light at 90 mmol. m-2 . s-1, transferred to the dark for 8 h, and reilluminated for 120 min before the rosette leaves of at least 10 plants per line were harvested. Total RNAs from three separate biological experiments were pooled (= 1 biological rep.) for the preparation of cDNA and the subsequent synthesis of biotin-labeled complementary RNA as recommended by Affymetrix.
Project description:We used microarrays to detail Arabidopsis gene expression in response to paraquat, a herbicide that acts as a terminal oxidant of photosystem I that in the light leads to the enhanced generation of superoxide and hydrogen peroxide inside plastids. Within a few hours after paraquat treatment changes in nuclear gene expression occur. Distinct sets of genes were activated that were different from those induced by another reactive oxygen species, singlet oxygen. Keywords: Time course
Project description:Formaldehyde is a toxic volatile organic compound and its mechanism of toxicity to plant has not yet been revealed. This experiment was designed to identify formaldehyde-responsible genes under exposure to low or high concentration of airborne formaldehyde for a short period of time. 7-weeks old Arabidopsis thaliana wild type (ecotype: Columbia) plants were exposed to gaseous formaldehyde at 1-2 ppm (low), 14-16 ppm (high), or less than 0.04 ppm (air control) at 24oC under light-condition for 150 minutes inside a chamber for formaldehyde exposure. Total RNA was isolated from rosette leaves of exposed plants and was applied to microarray analysis. We investigated into formaldehyde dose response on gene expression of Arabidopsis and tried to understand the toxic mechanisms of formaldehyde using an Affymetrix Arabidopsis genome array ATH-1.
Project description:Arabidopsis thaliana and Arabidopsis lyrata are two closely related Brassicaceae species, which are used as models for plant comparative biology. They differ by lifestyle, predominant mating strategy, ecological niches and genome organization. To identify heat stress induced genes, we performed RNA-sequencing of rosette leaves from mock-treated, heat-stressed and heat-stressed-recoved plants of both species.
Project description:We identified a small zinc finger protein, MBS, as a new mediator of singlet oxygen responses in Chlamydomonas and Arabidopsis. MBS is required for induction of singlet oxygen-dependent gene expression and, upon oxidative stress, accumulates in distinct granules in the cytosol of Arabidopsis cells. First, we recorded changes in light stress-regulated gene expression profiles after genetically perturbing MBS function by isolating mutants for the two MBS genes (MBS1 and MBS2) and by overexpression of MBS1 in Arabidopsis thaliana. Then, these light stress-related gene expression profiles were analyzed with respect to genes specifically responding to singlet oxygen and hydrogen peroxide/superoxide. The results indicated that MBS inactivation leads to an impaired response to singlet oxygen signaling under light stress.