Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Comparison of root transcriptomes in Arabidopsis thaliana plants supplied with different forms of inorganic nitrogen

ABSTRACT: Plants aquire nitrogen from the soil, most commonly in the form of either nitrate or ammonium. Unlike ammonium, nitrate must be reduced (with NADH and ferredoxin as electron donors) prior to assimilation. Thus, nitrate nutrition imposes a substantially greater energetic cost than ammonium nutrition. Our goal was to compare the transcriptomes of nitrate-supplied and ammonium-supplied plants, with a particular interest in characterizing the differences in redox metabolism elicited by different forms of inorganic nitrogen. We used microarrays to compare the short-term transcriptional response to either nitrogen supply or ammonium supply in Arabidopsis roots. Genes upregulated or downregulated by nitrate only, ammonium only, or both ammonium and nitrate were identified and analyzed. Arabidopsis thaliana (Col-0) plants were grown hydroponically until they reached growth stage 5.10. They were then transferred to a nitrogen-free medium for 26 hr and then supplied with 1 mM nitrate or 1 mM ammonium. RNA isolation (and subsequent microarray analysis) was performed on root tissue isolated just before nitrogen supply (time 0) and at 1.5 hr and 8 hr after nitrogen supply (1.5 hr nitrate, 8 hr nitrate, 1.5 hr ammonium, 8 hr ammonium).

ORGANISM(S): Arabidopsis thaliana

SUBMITTER: Matthew Escobar

PROVIDER: E-GEOD-29589 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Distinct signalling pathways and transcriptome response signatures differentiate ammonium- and nitrate-supplied plants.

Patterson Kurt K Cakmak Turgay T Cooper Andrew A Lager Ida I Rasmusson Allan G AG Escobar Matthew A MA

Plant, cell & environment 20100422 9

Nitrogen is the only macronutrient that is commonly available to plants in both oxidized and reduced forms, mainly nitrate and ammonium. The physiological and molecular effects of nitrate supply have been well studied, but comparatively little is known about ammonium nutrition and its differential effects on cell function and gene expression. We have used a physiologically realistic hydroponic growth system to compare the transcriptomes and redox status of the roots of ammonium- and nitrate-supp ...[more]

PMID: 20444219

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Project description:The metabolic response of maize source leaves to low nitrogen supply was analyzed in maize seedlings by parallel measurements of transcriptome and metabolome profiling. Inbred lines A188 and B73 were cultivated under controlled growth chamber conditions and supplied with either sufficient (15mM) or limiting (0.15mM) nitrate supply. Leaf lamina material was harvested at day 20 and day 30 after germination with the fifth and sixth leaf representing the main source leaf respectively. Four replicates were collecetd from individual plants for each combination of genotype, growth stage and nitrogen treatment. The leaf material was frozen, homogenised and aliquoted for transcriptome and metabolome analysis. The molecular data was further supplemented by phenotypic characterisation of the maize seedlings under investigation. Limited availability of nitrogen caused strong shifts in the metabolite profile of leaves. The transcriptome was less affected by the nitrogen stress but showed strong genotype and age dependent patterns. Nitrogen starvation initiated the selective down-regulation of processes involved in nitrate reduction and amino acid assimilation; ammonium assimilation related transcripts on the other hand were not influenced. Carbon assimilation related transcripts were characterized by high transcriptional coordination and general down-regulation under low nitrogen conditions. Nitrogen deprivation caused a slight accumulation of starch, but also directed increased amounts of carbohydrates into the cell wall and secondary metabolites. The decrease in N availability also resulted in accumulation of phosphate and by strong down-regulation of genes usually involved in phosphate starvation response, underlining the great importance of phosphate homeostasis control under stress conditions. Maize inbred lines A188 and B73 were cultivated in pots containing nutrient poor peat soil under the controlled conditions of a growth chamber. The plants were fertilized with modified Hoagland solutions containing either 15mM (high N) or 0.15mM nitrate (low N). Source leaf lamina were harvested at day 20 and day 30 after start of germination for parallel analysis of transcriptome and metabolome profiles. The molecular data is further supplemented by phenotypic characterization of the maize seedlings under investigation.

Project description:In comparison with provision of either ammonium or nitrate alone, simultaneously supplying both forms of N results in superior growth and yield for the majority of plants including rice. Using a rice 22K oligo-array, we performed transcriptome analysis to identify genes of rice (Oryza sativa L. ssp. japonica) responsive to change of N-supply forms and N-starvation. Using the supply of ammonium nitrate (one to one molar ratio) as control, the total number of root genes that were equal or more than two fold up- or down- regulated was 445, 324, and 781 by upon supply of either ammonium or nitrate or continuous N starvation, respectively for 96 h. In the shoot the equivalent numbers were much smaller only 32, 58, and 165, respectively. Clustering of the rice genes associated with different environmental stresses revealed substantial organ specificity of the root and shoot to N starvation, and also to the N supply form. Genes encoding transporters for ammonium and nitrate, nitrate reductase, glutamate dehydrogenase, and aspartate amino transferase, showed great response to change of the N supply form, especially to N starvation. Some of the genes involved in chlorophyll metabolism, carbon fixation and assimilation, were enhanced by ammonium supply only, but significantly suppressed by N-starvation. In the shoot there was increased expression of more general stress genes under nitrate when compared to ammonium nutrition. In the root the reverse situation was true with more apparent stress under ammonium nutrition. The microarray approach has revealed new levels of complexity in the response of rice to the form of N supply. Experiment Overall Design: Rice seedlings were grown in a hydroponic system in a growth chamber with control of both temperature and light. After normal growth for two weeks and for one week with completely avoiding any N source, the plants at four and a half leaf stage were re-supplied with ammonium nitrate (equal amount of either form of N), or only ammonium (ammonium sulphate and ammonium chloride), or only nitrate (calcium nitrate and magnesium nitrate), and continuing at zero N (N starvation). All the other essential nutrients were the same for all four treatments, except for sulfate and chloride which ranged between 1.1 â 2.6 mM and 0.5 â 2.5 mM, respectively. In Arabidopsis, addition of 3 mM Cl to âcontrolsâ did not produce any changes in the expression of genes in an experiment investigating the re-supply of 3 mM nitrate (Scheible et al., 2004). In other microarray experiments, extra addition of 5 mM Cl for Arabidopsis (Wang et al., 2000; Wang et al., 2004) and 1.4 mM sulphate for tomato (Wang et al., 2001) were used to replace nitrate for identifying the N deprivation responsive genes. Therefore, we assume that the relative smaller difference in sulfate and chloride concentrations among the four treatments in the normal supply range for plants would not significantly affect the expression profile of genes responsible for changes in N supply form and starvation in our experiments. Experiment Overall Design: For identifying the genes responding to the various N conditions by micro-array analysis, we extracted total RNA respectively from the roots and shoots at the 96 h after initiation of the four respective treatments. We used amplified and labeled cRNA from ammonium nitrate treatment as control, we performed array-hybridization for the cRNA from the treatment of single ammonium form, single nitrate form, or continuous N depletion, respectively. Agilent 60-mer oligonucleotide arrays containing 21,938 unique transcription units (Agilent Technologies, Tokyo, Japan) were used. Two biological replicates of each treatment were performed for microarray analyses.

Dataset Information

Comparison of root transcriptomes in Arabidopsis thaliana plants supplied with different forms of inorganic nitrogen

Publications

Distinct signalling pathways and transcriptome response signatures differentiate ammonium- and nitrate-supplied plants.

Similar Datasets

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