Transcription profiling of Arabidopsis 3 day-old seedlings of acn1-2 and the parent, Col-7 in the presence/absence of sucrose
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ABSTRACT:
ORGANISM(S): Arabidopsis thaliana
SUBMITTER: unknown unknown
PROVIDER: E-NASC-29 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:Plastids communicate with the nucleus by means of retrograde plastid signals. The far-red (FR) light insensitive Arabidopsis mutant laf6 disrupted in a plastid-localised ABC-like protein (atABC1) accumulates the plastid signal protoporphyrin IX (proto IX) and has attenuated nuclear gene expression (Moller et al.2001 Genes Dev. 15:90-103). Our data suggests that proto IX accumulation results in hypocotyl elongation in response to FR light and we have demonstrated that by inhibiting the plastid localised protoporphyrinogen IX oxidase (PPO) using flumioxazin wild-type plants phenocopy laf6 by accumulating proto IX with a concomitant loss of hypocotyl growth inhibition in a dose-dependent manner. It is at present unclear what effect increased proto IX has on nuclear gene expression and how this is integrated with photomorphogenic responses such as hypocotyl elongation.
2022-11-21 | E-NASC-42 | biostudies-arrayexpress
Project description:Many signalling pathways are involved in controlling gene expression during plant senescence. Pathways involving SA, JA and ethylene have a role in senescence but none are essential for the senescence process to occur. The aim of this experiment is to classify senescence-enhanced genes into groups depending on the signalling pathways that regulate them. This will provide useful information on the relative importance of each signalling pathway during senescence and allow us to separate potential senescence-specific genes and pathways from the stress response pathways.Mutants in genes in the ethylene pathway (ein2) and the jasmonate pathway (coi1) and the NahG transgenic plant which is defective in the salicylic acid pathway will be grown until the mid flowering stage. Fully developed green and partially senescent leaves will be harvested from the plants at this stage. In addition, two different lines of Arabidopsis (Col-5 glabrous and Col-0) will be grown as controls. Leaves will be harvested from the two control plants before flowering (green) and at mid flowering as above. The control plants will be harvested at two stages to identify the senescence- enhanced genes. The effects of each mutation on the senescence related expression of these genes will then be studied.Mutant RNAs will be isolated in duplicate. The two control accessions will act as replicates for the wild type. Two wild type accessions will be used to reduce possible differences that could be observed the mutants due to slight differences in background.
2022-11-21 | E-NASC-17 | biostudies-arrayexpress
Project description:SKS mutant (snakeskin) vs wildtype
2022-11-21 | E-NASC-57 | biostudies-arrayexpress
Project description:Aim: To identify regulatory factors that control: (1) chloroplast protein importand (2) chloroplast-to-nucleus signalling. This project is a joint proposal from the Jarvis lab which is interested in chloroplast protein import [1] and the Moller lab which is interested in plastid-to-nucleus signalling [2]. Background: The majority of chloroplast proteins are encoded in the nucleus and imported post-translationally into chloroplasts. The abundance of chloroplast proteins may therefore be regulated at multiple levels. It is well documented that the nuclear gene expression is responsive to (largely unknown) signals from the chloroplast [23] and evidence is now emerging that protein import is also a regulated process [1]. Protein import into chloroplasts is mediated by protein complexes in the outer and inner envelope membranes called Toc and Tic respectively. Biochemical studies of pea chloroplasts identified several Toc/Tic components. These proteins are mechanistic or structural components of the import apparatus. Arabidopsis homologues of the pea Toc/Tic proteins were identified by the AGI. Pea Toc34 is represented in Arabidopsis by two genes "Toc33 and Toc34" and pea Toc75 is represented by three genes. These different Tocs have different expression patterns and are proposed to have different precursor protein recognition specificities. The factors that regulate Toc expression in concert with the needs of plastids in developmentally different cells are unknown. Proposal: Two Arabidopsis mutants will be analysed. The ppi1 mutant is null for the putative precursor protein receptor Toc33 [1]and the ppi3 mutant is null for a putative component of the protein import channel Toc75-IV (on chromosome IV). ppi1 plants are yellow-green in appearance but remarkably healthy and grow only slightly more slowly than wild type. By contrast ppi3 plants are indistinguishable from wild type by eye although analysis of the mutant's chloroplast proteome is beginning to reveal some differences (K. Lilley personal communication). Gene expression changes in ppi1 are likely to be quite extensive. Retardation of chloroplast development in ppi1 will activate retrograde signalling pathways so that many nuclear photosynthetic genes are down-regulated. Changes in the expression of photosynthetic genes and of the genes responsible for mediating these responses may therefore be observed. Any regulatory and signalling genes identified will be of interest to the Moller lab. The expression of factors that regulate Toc/Tic gene expression may also be altered in ppi1. It should be possible to distinguish these factors from those involved in the general control of chloroplast gene expression by comparing the results from the two mutants. Genes affected in both mutants are more likely to be involved in regulating chloroplast import since it is unlikely that widespread changes in gene expression will be observed in ppi3. Changes in the expression of factors that regulate import post-translationallyand of the Toc/Tic genes themselves (many are on the RNA) may also be observed. References: 1. Jarvis P. et al. (1998) Science 282: 100-103. 2. Moller S.G. et al. (2001) Genes Dev. 15:90-103. 3. Jarvis P. (2001) Curr. Biol. 11: R307-R310.
2022-11-21 | E-NASC-35 | biostudies-arrayexpress
Project description:As part of an investigation into mechanisms of HDG silencing in Arabidopsis, we have produced transgenic plants containing extra copies of the chalcone synthase (CHS) gene. The CHS gene mediates an early step in the biosynthesis of the purple pigment anthocyanin. The insertion of extra copies of CHS in Arabidopsis caused the gene to be silenced in some plants. Seeds harvested from these CHS-silenced plants were mutated by treatment with ems. The progeny of these seeds were screened for "revertants" in which the effects of CHS silencing was alleviated and plants were able to produce anthocyanin. These revertants were found to contain a single recessive mutation; the trait has been termed hog1 (for homology dependant gene silencing 1). Our previous experiment used the Affymetrix 8200 chip to make comparisons between gene expression in the two genetic variants: the CHS-silenced type (ECG) and the anthocyanin-producing revertants (15B). Results showed that there were over 100 genes with at least a 10-fold increase or decrease in expression. However, the variation between 2 reps of each genetic variant was high. We would now like to carry out a modified version of this experiment using the 25K Affymetrix chip. It is intended to increase the number of reps to 4, and take samples at an earlier stage than previously in order to decrease the effect of developmental spread. To reduce the effects of interplant variability, samples will be generated from total plant tissue from a pool of 10 plants at GS 1.04. RNA will be purified using RNeasy kits from Qiagen.
2022-11-21 | E-NASC-36 | biostudies-arrayexpress
Project description:Background: Release of the caesium radioisotope 137Cs during weapons testing and industrial activity has contaminated thousands of hectares of agricultural land. Ingesting 137Cs has damaging and, sometimes, fatal effects. Most Cs enters the food chain through plants. The generation of _safe_ crops that exclude Cs and can be cultivated on contaminated land requires knowledge about the mechanisms for Cs uptake. Caesium is chemically similar to potassium (K) and might enter plants through K+ transporters in the plasma membrane of root cells. To determine which transporters mediate Cs entry to plants, we have compared the accumulation of Cs and K by wildtype Arabidopsis with mutants lacking specific K+ transporters. Preliminary results showed that Cs concentration in the shoots of akt1-1, cngc1 and cngc4 (obtained from the Wisconsin T-DNA knockout facility) differed significantly from the Wassilewskija wildtype (Ws-2). A cursory investigation of their transcriptome, using the Affymetrix Arabidopsis 8K GeneChip, showed that the expression of several genes encoding K+ transporters differed between mutants and wildtype plants. The aim of this GarNet project is to confirm the previous observations and to identify further genes that are differentially expressed in mutant and wildtype plants and which might impact on Cs accumulation. Methods: Arabidopsis mutants akt1-1 (N3762), cngc1 and cngc4 and their parental ecotype Wassilewskija -2 (N1601) will be sown on MS agar and transferred to hydroponics 21 days after germination. Seedlings will be grown for a further 7 days on full nutrient solution under continuous light in a Saxcil growth cabinet. RNA will be extracted from roots of mutant and parent (control) plants at the same growth stage and twelve complete-genome Affymetrix GeneChips (3 biological replicates of material from wildtype and 3 mutants) are requested to determine the differences in their transcriptome under comparable environmental conditions.
2022-11-21 | E-NASC-31 | biostudies-arrayexpress
Project description:Regulation of expression of genes encoding chloroplast components is critical to the autotrophic plant and never more so than in the cotyledons of the de-etiolating seedling. Many chloroplast proteins are nuclear-encoded and a retrograde signal from the chloroplasts (the Plastid Signal) modulates nuclear transcription. However, not all chloroplast-targeted genes are subject to this control and not all plastid-dependent nuclear genes are chloroplast-targeted. We therefore aim to provide the most comprehensive screen yet of which genes are affected by plastid-signalling. To specifically knock-out positive plastid signalling in light-grown cotyledons, the herbicide Norflurazon (NF) is supplied in the growth medium, causing a carotenoid deficiency that leaves the chloroplasts vulnerable to photobleaching. This blocks the expression of a subset of nuclear genes, such as Lhcb and HEMA1. Two pairs of RNAs will directly compare the transcription in seedlings grown under continuous white light with and without NF. A third RNA will also be compared from a mutant that shows a degree of constitutive positive plastid signalling. These two mutants act synergistically to counteract the effect of NF on nuclear transcription. The gun1,gun5 double mutant maintains a significantly higher level of Lhcb and HEMA1 expression in the presence of photobeached chloroplasts than the NF-treated wild-type. This transcriptome set will therefore complement RNA1 (wild-type+NF) and indicate which of the genes identified from the RNA1/RNA2 comparison are subject to the particular gun1/gun5 plastid signalling pathway(s). The growth of conditions of the seedlings (namely on MS medium supplemented with 1.5% sucrose, for 3 days under continuous WL following 2 days germination in darkness) has been chosen from the results of our own recent studies using Northern blotting techniques that show these conditions to maximise the respective NF and gun mutant effects on Lhcb and HEMA1 gene expression. This experiment is part one of a two-part study to compare the transcriptional output of this NF-affected pathway with that of a newly discovered FR-mediated pathway. A subsequent array experiment will assess the nuclear response as affected by this FR/ phyA-input pathway and the two sets of array data will be compared and contrasted. Note: Col-0 wild-type (NASC code N1092). gun1,gun5 double mutant(obtained from Enriquez Lopez-Juez, Royal Holloway, University of London.(Mochizuki et al. 2001 PNAS 98: 2053-2058). This line cannot be donated by us as it is the IP of Joanne Chory (SALK Institute, USA). Treatment = a herbicide (Norflurazon) application which leads to chloroplast photobleaching and hence down regulation of nuclear genes dependent on plastid signalling from intact chloroplasts.
2022-11-21 | E-NASC-40 | biostudies-arrayexpress
Project description:At high concentrations ceasium (Cs) is toxic to plant growth. This toxic effect may occur when Cs blocks potassium (K) uptake mechanisms in plants. Consequently, plants starved of K and plants exposed to toxic concentrations of Cs should have similar gene expression patterns. To test this hypothesis, Arabidopsis will initially be grown on agar containing 1/10 MS salts before being transferred to either 1/10 MS nutrient solution (control plants), 1/10 MS nutrient solution containing 2 mM Cs, or 1/10 MS nutrient solution with no K. Roots and shoot will then be harvested seven days after transfer and used to challenge ATH1 GeneChips.
2009-09-03 | E-NASC-61 | biostudies-arrayexpress
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.
2022-11-21 | E-NASC-16 | biostudies-arrayexpress
Project description:Background: The UK horticultural and agricultural industries routinely apply large amounts of inorganic fertiliser to maintain crop yield and quality, since chemical assays of soil nutrients are unreliable. Excessive fertiliser applications are costly and can lead to unnecessary pollution. A possible solution is to use sensor (GM or non-GM) technologies that exploit the changes in plant gene expression under incipient nutrient deficiency. Aim: The aim of this project is to use mutants with reduced leaf phosphate contents to identify genes upregulated in response to phosphate stress. Preliminary gene expression analysis has identified several phosphate responsive genes to be upregulated in the pho1 mutant. However, further replicates of the experiment are required to confirm these changes. Methods: Arabidopsis mutant pho1 (N8507) and its parent ecotype Columbia 2 (N907) will be grown on MS agar under identical conditions. RNA will be extracted from the rosette leaves of both parent and mutant and the same growth stage. By comparing the expression profiles, we will be able to differentiate between genes that are upregulated in leaves experiencing phosphate stress. Previously, two GeneChips have been used (mutant and parent) to provide preliminary data. A further two biological replicates are now required to confirm these results. Promoters and transcripts of these genes will underpin the development of novel sensor technologies, and knowledge of the gene expression profiles will improve our understanding of the physiology of plant mineral nutrition.
2022-11-21 | E-NASC-60 | biostudies-arrayexpress