Project description:Plant respiration responses to elevated growth [CO2] are key uncertainties in predicting future crop and ecosystem function. In particular, the effects of elevated growth [CO2] on respiration over leaf development are poorly understood. This study tested the prediction that, due to greater whole-plant photoassimilate availability and growth, elevated [CO2] induces transcriptional reprogramming and a stimulation of nighttime respiration in leaf primordia, expanding leaves, and mature leaves of Arabidopsis thaliana. In primordia, elevated [CO2] altered transcript abundance, but not for genes encoding respiratory proteins. In expanding leaves, elevated [CO2] induced greater glucose content and transcript abundance for some respiratory genes, but did not alter respiratory CO2 efflux. In mature leaves, elevated [CO2] led to greater glucose, sucrose and starch content, plus greater transcript abundance for many components of the respiratory pathway, and greater respiratory CO2 efflux. Therefore, growth at elevated [CO2] stimulated dark respiration only after leaves transitioned from carbon sinks into carbon sources. This coincided with greater photoassimilate production by mature leaves under elevated [CO2] and peak respiratory transcriptional responses. It remains to be determined if biochemical and transcriptional responses to elevated [CO2] in primordial and expanding leaves are essential prerequisites for subsequent alterations of respiratory metabolism in mature leaves. Arabidopsis plants were grown in either ambient (370 ppm) or elevated (750 ppm) CO2. Leaf number 10 was harvested when it was a primordia, expanding, or mature in each of the CO2 treatments.
Project description:affy_rnai_cadpoplar - affy_rnai_cadpoplars - This experiment aims to characterize global gene expression in young xylem of transgenic RNAi-CAD poplars in comparison to WT poplars. Cinnamyl Alcohol Dehydrogenase (CAD) is the final enzyme involved in the monolignol biosynthesis pathway. Transgenic poplars were produced using RNAi strategy (pHellsgate 8 vector, Helliwell and Waterhouse, 2003) and exhibited the expected phenotype (red xylem, reduced CAD activity).Biological question (15 lines max):This experiment aims to characterize global gene expression in young xylem of transgenic RNAi-CAD poplars in comparison to WT poplars. Cinnamyl AlcoholDehydrogenase (CAD) is the final enzyme involved in the monolignol biosynthesispathway.Transgenic poplars were produced using RNAi strategy (pHellsgate 8 vector, Helliwell and Waterhouse, 2003) and exhibited the expectedphenotype (red xylem, reduced CAD activity). -RNAi-CAD transgenic poplars were produced using hairpin RNAi strategy (pHellsgate 8 vector, Helliwell and Waterhouse, 2003). For this transcriptome anaylsis, 2 independent transgenic lines (named pHG8-CAD2 and pHG8-CAD19) from the same transformation procedure were used as biological repeats. Four-month-old poplar plants were inclined at 30° in the greenhouse and sampled after 26 days. Young differentiating xylem originating from the lower side of stems - opposite wood - (ODX) was sampled on each individual tree by scrapping slightly the debarked stem with a scalpel. Samples were immediately flash frozen in liquid nitrogen, ground with mortar and pestle, and total RNAs were extracted from fine ground powder using the QIAGEN miRNeasy kit according to the manufacturer. One Affymetrix slide corresponds to a pool of RNA samples from 2-4 individual trees (WT, RNAi-CAD transgenic lines 2 and 19). Total number of slides = 2 genotypes (WT/RNAi line) x 1 tissue x 2 biological replicates = 4 slides were done. 4 arrays - poplar; normal vs rnai mutant comparaison
Project description:Plants can cope with stress better if they experience a mild form of the stress before the actual \\"real\\" stress event. In Arabidopsis thaliana it is known that plants that harboured eggs of the White cabbage butterfly (Pieris brassicae) before larval feeding can defend better against the herbivore stress. The main aim of the experiment was to compare the priming effect induced by insect egg deposition of Pieris brassicae between vegetative and reproductive (first open flowers) Arabidopsis thaliana plants on the transcriptional level. We used a full factorial setup consisting of a) untreated control plants , b) plants which experienced eggs for 6 days without larval feeding after that period, c) plants which experienced no eggs before larval feeding for 24 hours d) plants which experienced eggs for 6 days and larval herbivory for 24 hours. This setup was conducted with 6 week old vegetative plants and 10 week old reproductive plants were the first flowers were open. For all treatments leaf tissue from the leaves that experienced egg oviposition and/or larval feeding were collected. From reproductive plants flower buds were collected as well.
Project description:Alternative splicing plays a major role in expanding the potential informational content of eukaryotic genomes. It is an important post-transcriptional regulatory mechanism that can increase protein diversity and affect mRNA stability. Cold stress, which adversely affects plants growth and development, regulates the transcription and splicing of plants splicing factors. This affects the pre-mRNA processing of many genes. To identify cold regulated alternative splicing we applied Affymetrix Arabidopsis tiling arrays to survey the transcriptome under cold treatment conditions. Two-week old Arabidopsis seedlings grown on agar were subjected to 24 hours of cold (4°C) treatment under long day conditions. Control and cold-treated plants were harvested at the same time to ensure that observed differences would not be due to circadian clock effects on transcripts. Total RNA from four biological repeats were used for microarray hybridization.
Project description:Three bZIP transcription factors (TFs), namely GBF1, HY5, and HYH, form heterodimers with each other and regulate photomorphogenesis in an interdependent manner. GBF1 acts as both a positive and negative regulator of photomorphogenesis, whereas HY5 and HYH mainly act as positive regulators of photomorphogenesis. To study the effect of HY5 and HYH on GBF1-mediated genome-wide expression, transcript profiling was performed in the gbf1 single mutant and gbf1hy5 and gbf1hyh double mutants. Our study revealed that GBF1 mainly acts antagonistic to HY5 and HYH for genome-wide expression. Four-day-old constant white-light grown Arabidipsis seedlings of wild-type (Col-0), gbf1 mutant, gbf1 hy5 double mutant and gbf1 hyh double mutant were harvested for total RNA extraction and Affymetrix microarray hybridisation. Two biological replicates of each sample were used for hybridisation and data analysis. Data were analysed using GeneSpring software by utilising the RMA algorithm. To draw the conclusions from this study, probe level intensity of gbf1, gbf1 hy5, and gbf1 hyh was normalised against the probe level intensity of wild-type, and also the probe level intensity of gbf1 hy5 and gbf1 hyh double mutants was normalised against the probe level intensity of the gbf1 single mutant.
Project description:UV-B (280-320 nm) exposure causes serious damage in plants, limiting their growth and survival, effects that are partly counteracted by repair mechanisms active in plants receiving accompanying visible radiation. Though no particular UV-B receptor has been identified to date, there is strong evidence to indicate that certain aspects of UV-B perception are receptor-mediated. Investigations of down-stream signalling events have thus far indicated broad similarities to pathogen-induced defence responses in plants. In order to identify genes in Arabidopsis that may be up- or down- regulated specifically in response to UV-B exposure and compare them to genes whose expression is altered in plants challenged by an avirulent isolate of Peronospora parasitica (downy mildew), we propose to analyse the transcriptional profiles for the following treatments:; 1. UV-B Responses; "A-1" Columbia (Col-0) exposed to supplementary UV-B/UV-A* with a background of low photosynthetically active radiation (PAR of 20 micromol m-2 s-1) for 1.5 photoperiods (photoperiod = 12h). [UV-B treatment]; "A-2" Col-0 exposed to supplementary UV-A and low PAR for 1.5 photoperiods [control for UV-B treatment]; "A-3" Col-0 exposed to visible light only (low PAR) (no UV) for 1.5 photoperiods [control for UV effects in general].* There are no pure sources of UV-B light available. 2. Pathogen Responses; "A-4" Col-0 spray-inoculated with P. parasitica isolate HIKS-1 (recognised by the R-gene RPP7). After spraying, plants were kept covered in plant propagators and transferred to an 18 degreeC growth chamber. !Samples for RNA extraction were taken 72h after inoculation. "A-5" The viability of spores was also checked by parallel spraying of the susceptible mutant, Col-rpp7. [pathogen treatment]; "A-6" Col-0 mock treated with water, covered and transferred to an 18 degree C growth chamber, 72h prior to sampling. [control for pathogen treatment]; In all experiments, we are using RNA from leaves taken at the same time of day (6 h into the 12 h photoperiod) from 4.5-week old plants grown under 12h photoperiod. All treatments were normalised against PR-1 expression levels to ensure comparability between UV-B and pathogen treatments. Due to the difficulty in distinguishing between local and systemic induced responses in UV-B treated plants, we are using RNA from whole rosettes for both the UV-B and pathogen treatment for better comparability among treatments. The degree of similarity between these two sets of transcriptional changes will complement and help interpret our experimental data on changes in resistance to pathogens in plants pre-treated with UV-B. Moreover, the data set obtained would allow for identification of UV-B specific changes in gene expression including cis-acting UV-B-responsive promoter elements. Experimenter name = Julia Brueggemann; Experimenter phone = 01789 470 382; Experimenter fax = 01789 470 552; Experimenter address = Horticulture Research International; Experimenter address = Wellesbourne; Experimenter address = Warwickshire; Experimenter zip/postal_code = CV35 9EF; Experimenter country = UK Experiment Overall Design: 6 samples were used in this experiment
Project description:The sfr6-1 mutant of Arabidopsis has been shown to be defective in freezing tolerance and fails to express a number of cold-regulated genes to normal wild type levels. The aim of this experiment was to test whether two other mutant alleles, sfr6-2 and sfr6-3 showed similar defects in cold-inducible gene expression. Two experiments were performed. In each, one sfr6 mutant was cold-treated alongside its corresponding wild type.
Project description:Lotus japonicus is a model legume broadly used to study transcriptome regulation under different stress conditions and microorganism interaction. Understanding how this model plant respond gainst alkaline stress will certainly help to develop more tolerant cultivars in economically important Lotus species as well as in other legumes. In order to uncover the most important response mechanisms activated during alkaline stress, we explored by microarray analysis the transcriptome regulation occurring in the phenotypically contrasting ecotypes MG-20 and Gifu B-129 of L. japonicus after 21 days of alkaline stress.
Project description:The aim is to identify early gibberellin responsive genes in a gibberellin deficient strain such as ga1-3. Such genes are likely regulated by DELLA proteins which are master gibberellin repressors. DELLA proteins are rapidly degraded after gibberellin treatment, but their direct target genes still need to be elucidated. Experiment Overall Design: A set of 4 biological replicates was generated for each treament. Arabidopsis seedlings were treated with water or 2 uM GA4 and whole shoots collected after 1h. A comparison of water vs. GA4 treated samples should render a list of early gibberellin responsive genes.