ABSTRACT: This experiment was designed to identify transcripts which are changed in plants deficient for evolutionary conserved EST1B gene. A mutation in est1b leads to a constitutive up-regulation of a PAD4-dependent pathogen response pathway. To eliminate secondary effects of the constitutive pathogen response in est1b mutants we will analyze transcriptoms in plants in which lack PAD4. Keywords: Expression profilling by array 6 samples were used in this experiment
Project description:This experiment was designed to identify transcripts which are changed in plants deficient for evolutionary conserved EST1B gene. A mutation in est1b leads to a constitutive up-regulation of a PAD4-dependent pathogen response pathway. To eliminate secondary effects of the constitutive pathogen response in est1b mutants we will analyze transcriptoms in plants in which lack PAD4. Keywords: Expression profilling by array
Project description:In order to better understand the transcriptional networks triggered by pathogen inoculation, we monitored gene expression in leaves of mutant Arabidopsis plants, inoculated with Pseudomonas syringae ES4326 and wild type Col-0 plants grown in parallel. Individual leaves were injected in the morning using a needle-less syringe with 10E5 cfu cm-2 PsmES4326 (suspended in 5 mM MgSO4). For the wild type, leaves were also mock treated with 5 mM MgSO4. Leaves were harvested 24 hours later. Plants were grown in pots with BM-2 soil (Berger Peat Moss Ltd, Quebec, Canada) at a density of 9 plants per pot and kept at 22 degrees Celsius with 75% humidity and a 12 hour day length. Keywords: Expression profiling by array 24 samples were used in this experiment
Project description:Plants live in soils that vary considerably, both spatially and over time, in terms of nutrient composition and pH. Consistently, plants have to recognize and adapt to these changes by altering their structure and metabolism. The goal of this array analysis is to characterize the global transcriptional response to external pH changes in roots, which to date is almost unexplored. Arabidopsis thaliana (Columbia-0) were grown in hydroponic cultures in basic nutrient solution. Two days before treatment the media was shifted to nutrient solution containing 5mM MES, pH 6. At the time of the treatment start (4 hours after light on) the plants were shifted to nutrient solutions of pH 4.5 and 6.0 (control). Root RNA samples from time point 1 and 8 hour after treatment start is used for array analyzes. Keywords: Expression profilling by array 12 samples were used in this experiment
Project description:We characterized two independent insertional mutants of the AtEXO70A1 gene, encoding a subunit of the exocyst complex. Homozygous mutants exhibit a suite of phenotypic defects: polar growth of root hairs and stigmatic papillae is disturbed; organs are generally smaller; plants show loss of apical dominance and an indeterminate growth where instead of floral meristems new lateral inflorescences are initiated in a reiterative manner; exo70A1 mutants have dramatically reduced fertility. These results suggest that EXO70A1 is involved in cell and organ morphogenesis. Keywords: Expression profiling by array 4 samples were used in this experiment
Project description:In addition to the canonical RNAi pathways that targets mRNAs in the cytoplasm, several RNA-dependent pathways operate in the nucleus to induce sequence-specific epigenetic modifications. One specialized type of RNAi-mediated pathway is RNA-directed DNA methylation (RdDM). During RdDM, nuclear DNA with sequence identity to the trigger dsRNA is de novo methylated at almost all cytosine residues, providing a mark for the formation of transcriptionally silent heterochromatin. Genetic forward screens identified the RPD3-like histone deacetylase HDA6 as the enzyme responsible for the histone deacetylation step of RdDM and suggest that HDA6 might have acquired specific functions for RNA-directed transcriptional silencing processes [Aufsatz et al., 2002a; Aufsatz et al., 2002b]. Complete loss-of-function mutants for AtHDA6 (rts1-1; RNA-mediated transcriptional gene silencing) exhibit reactivation of RdDM-silenced promoters, despite the continuous presence of the silencing-inducing RNA signal. One of the found mutant alleles, rts1-5, has an amino acid substitution located at a conserved position within the HDAC domain (Naumann et al., manuscript in preparation). This mutant is characterized by strong reactivation of an RdDM-silenced target promoter, despite maintaining wild-type levels of cytosine methylation. An evaluation of the transcription pattern among the mutants with opposite methylation phenotype and wild-type plants should show which genes are differentially regulated between the mutants in comparison to wild-type plants. Keywords: Expression profiling by array 9 samples were used in this experiment
Project description:The aim of the experiment is to look at transcriptional changes in null mutants of APS kinase. There are four APS kinase isoforms in Arabidopsis, we are interested in the double mutant APK1/APK2, created by crossing two single salk lines. The transcriptomes of WT (Col-0) plants and the double knockout (ab) will be compared. The plants were grown under controlled environment conditions of 10h day, 14h night, 22 degrees centigrade, 60% humidity for five weeks. 10 whole rosettes were pooled for each replicate, there are three replicates for each genotype. Keywords: Expression profiling by array 6 samples were used in this experiment
Project description:In plant axillary bud dormancy and outgrowth are regulated by phytohormones, but it is still unknown about its molecular mechanism. We reveal that Arabidopsis axillary buds located at axil of rosette leaves show dormancy and that this is broken by the decapitation of main stem, resulting in the bud outgrowth. To investigate about the molecular mechanisms of dormancy and outgrowth, we carried out gene expression analysis during axillary shoot outgrowth in Arabidopsis wild type Columbia accession. Since axillary buds did not initiate outgrowth (dormancy) at 5 day after bolting of main stem, we used 5-day bolted plants as a control (before decapitation). Then, main stems were decapitated, and axillary shoots were collected at 24 hours after decapitation (named as growing shoot). Total RNA was prepared from either control or growing shoots and used for the microarray analysis. We carried out duplicate microarray analysis using independent plant materials.Ref):Tatematsu et al., Plant Physiol. 138: 757-766 (2005). Keywords: Expression profilling by array 4 samples were used in this experiment
Project description:The aim of this work is to investigate whether A. thaliana senses low temperature by perceiving changes in membrane fluidity. To this end, we have performed an experiment to test whether mutant or transgenic plants with altered membrane lipid composition, regulate their gene expression in the same manner as wild type plants in response to cold. Previous work has demonstrated that a change in the expression levels of a number of genes is important in acquiring tolerance to low temperatures. Chemicals which rigidify cell membranes in such a way as to mimic the effects of cold have been shown to be able to induce the expression of such genes. However, because of the non-specific nature of such chemical treatments, it has not been possible to demonstrate unequivocally that the changes in gene expression observed were the result of changes in membrane fluidity. All of the mutants used in our experiment, fab1, fad2-2 and the fad3/fad7/fad8 mutant, have increased lipid saturation levels compared to wild type plants and are thought to have reduced membrane fluidity. The fab1 mutant is also known to be sensitive to chilling. In the fab1 mutant the elongation of 16:0 fatty acids to 18:0 is reduced. The fad2-2 mutant has reduced 18:1 desaturase activity and hence reduced amounts of polyunsaturated phospholipids. The fad3/fad7/fad8 triple mutant is deficient in 18:2 desaturase activity and consequently unable to synthesise trienoic fatty acids. The transgenic line used contained a 35S::FAD3 transgene and in contrast to the mutants tested, should have increased lipid desaturation and increased membrane fluidity. A. thaliana ecotype Col-0 was used as the wild type control for the fab1 and fad2-2 mutants, in addition to the 35S::FAD3 line. The fad3/fad7/fad8 mutant had previously been transformed with the 35S::apoaequorin transgene and a Columbia line expressing apoaequorin under the control of the same promoter, was included to control for the presence of aequorin. Nine day old seedlings grown in petri-dishes on MS were transferred from their growth room (20 oC, 16 h photoperiod, 100 E m-2 s-1) to a growth cabinet (20 oC, 16 h photoperiod,160 m-2 s-1) 24 hours before the experiment began. The next day, one petri-dish of seedlings from each line of plants used was transferred to a cabinet running at 5 oC (16 h photoperiod,160 E m-2 s-1). Control plates remained at 20 oC. Seedlings were harvested after three hours and frozen in liquid nitrogen. 12 samples were used in this experiment
Project description:The genomic response to low levels of nitrate was studied in Arabidopsis using the Affymetrix ATH1 chip containing more than 22,500 probe sets. Arabidopsis plants were grown hydroponically in sterile liquid culture on ammonium as the sole source of nitrogen for 10 d, then treated with 250 um nitrate for 20 min. The response to nitrate was much stronger in roots (1,176 genes showing increased or decreased mRNA levels) than in shoots (183 responding genes). In addition to known nitrate-responsive genes (e.g. those encoding nitrate transporters, nitrate reductase, nitrite reductase, ferredoxin reductase, and enzymes in the pentose phosphate pathway), genes encoding novel metabolic and potential regulatory proteins were found. These genes encode enzymes in glycolysis (glucose-6-phosphate isomerase and phosphoglycerate mutase), in trehalose-6-P metabolism (trehalose-6-P synthase and trehalose-6-P phosphatase), in iron transport/metabolism (nicotianamine synthase), and in sulfate uptake/reduction. In many cases, only a few select genes out of several in small gene families were induced by nitrate. These results show that the effect of nitrate on gene expression is substantial (affecting almost 10% of the genes with detectable mRNA levels) yet selective and affects many genes involved in carbon and nutrient metabolism. Keywords: Expression profilling by array 8 samples were used in this experiment
Project description:Eukaryotic cells have evolved a mechanism called nonsense mediated mRNA decay (NMD) that detects and degrades aberrant mRNAs that contain premature termination codons (PTCs). NMD has recently acquired broader importance as it has been found to regulate not only aberrant mRNAs but also a great diversity of transcripts, including wild type genes in mammals, Drosophila and yeast. Seven proteins are the core of the NMD complex: SMG1, SMG2 (UPF1), SMG3 (UPF2), SMG4 (UPF3), SMG5, SMG6 and SMG7. Plants have orthologues of most of these proteins. We have identified and characterized a number of alleles of UPF1, UPF3 and SMG5 and made 35S:UPF2 RNAi (upf2i) transgenic plants, all of which share some phenotypic characteristics. Transcriptome analysis of upf1 and upf3 mutants has identified a subset of genes coregulated by UPF1 and UPF3 and, therefore, by NMD (unpublished data). By doing further transcriptome analysis on smg5 mutants and upf2i plants we aim to build a more robust subset of NMD targets in Arabidopsis. RNA will be extracted from 17 day-old mutant, transgenic and wild type seedlings grown at 22-24 C under constant light. 6 samples were used in this experiment