Project description: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).
Project description: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.
Project description:affy_nitrogen_medicago - affy_nitrogen_medicago - Experiment has been designed to characterize the molecular expression patterns associated to a contrasted modification of the nitrogen status of the whole plant. The systemic effects of nitrogen status modifications are investigated and compared on non nodulated plant supplied with NO3, NH4 or nodulated plants (Sinorhizobium meliloti 2011) supplied with air. The root systems were separated in two compartments of unequal sizes (split root system). Two treatments were applied on the larger compartment in order to modulate the nitrogen status of the plant: for the S treatment, roots are supplied with nutrient solution containing 10 mM NH4NO3,, whereas for the C treatment, roots are supplied with nitrogen free medium. In the case of N2 fixing plants, N limitation was obtained by replacing air by a mixture of Ar and O2 80 per cent and 20 per cent. The effects of these treatments were investigated on roots of the minor compartment supplied continuously with either NO3 1 mM, NH4 1 mM or air (N2) and on the shoots. We were also interested in the molecular expression patterns associated to the roots deprived of N.-The root system of non-nodulated (NO3- and NH4+) or nodulated (N2) plants is split into two unequal parts and each one is installed in a separate compartment. For the S treatement, the major root part is supplied with NH4NO3 10 mM whereas the minor part is supplied with either NO3- 1mM, NH4+ 1mM or N2. For the C treatement, the major root part is supplied with nitrogen-free nutrient solution whereas the minor part is supplied with either NO3- 1mM, NH4plus 1mM or N2. Each treatement is four days long. Samples of roots of six biological types (NO3S, NO3C, NH4S, NH4C, N2S and N2C) were collected. Two biological repeats per biological types have been analyzed. The effect of the S and C treatments were investigated for each N sources by comparing Affymetrix transcriptomes (NO3C vs NO3S, NH4C vs NH4S, N2C vs N2S). Keywords: treatement (nitrogen-sufficient) vs treatement (nitrogen-limited)
Project description:To optimize access to nitrogen under limiting conditions, root systems must continuously sense and respond to local or temporal fluctuations in nitrogen availability. In Arabidopsis thaliana and several other species, external N levels that induce only mild deficiency stimulate the emergence of lateral roots and especially the elongation of primary and lateral roots. However, the identity of the genes involved in this coordination remains still largely elusive. In order to identify novel genes and mechanisms underlying nitrogen-dependent root morphological changes, we investigated time-dependent changes in the root transcriptome of Arabidopsis thaliana plants grown under sufficient nitrogen or under conditions that induced mild nitrogen deficiency.
Project description:affy_agro-bi_medicago - Identification of genes from the model legume Medicago truncatula whose expression is affected by the plant nitrogen status, with or without inoculation with the symbiotic bacteria Sinorhizobium meliloti. - Comparison of the supernodulant, nitrogen-insensitive, sunn-2 mutant with the A17 wild type genotype.-The plant root systems of plants were split into two parts, each one being installed in a separate compartment. For the “S” treatment, one part was supplied with 10 mM NH4NO3 while the other part was supplied with a nitrogen-free nutrient solution. For the “L” treatment, one part was supplied 0.5mM NO3- and the other part was supplied with the nitrogen free solution. Eight biological materials (designated AL, AS, SL, SS, IL, IS, NIL, NIS), with three biological repeats for each, were collected and analyzed. The effects of the S and L conditions were investigated on wild-type A17 (AL vs. AS) and sunn-2 mutant plants (SL vs. SS); one set of A17 plants was inoculated with Sinorhizobium meliloti (IL vs. IS), harvested at four days post inoculation and compared to non-inoculated plants (NIL vs. NIS). Keywords: growth in nitrogen-sufficient (s) vs. nitrogen-limited (l) conditions
Project description:gnp3-b4_nitrogen_starvation - nitrogen starvation and re-supply - What are the transcriptomic short- and long-term plant responses to nitrogen starvation and nitrogen re-supply? - WS Arabidopsis ecotype were grown on 6mM nitrate as sole nitrogen source during 35 days under short days . At T0, plants were then starved for nitrate for 10 days and root and shoot samples were harvested separately 2 and 10 days after treatment (T2, T10). Then, nitrate (6 mM) was re-supplied for 1 and 24 hours (T+1, T+24). Keywords: time course
Project description:Of all the essential nutrients, nitrogen is the one most often limiting for plant growth. Nitrogen can be taken up by plants in two ways. One possibility is through ammonium and nitrate, which are the predominate inorganic forms of nitrogen in soils. The second possibility is the uptake of air-born nitrogen through plant-associated mircoorganisms in root nodules. The majority of plants able to form such nitrogen-fixing root nodules are in the legume family Fabaceae. Here we present a third possibility M-bM-^@M-^S a new pathway, termed as nitric oxide (NO)-fixation pathway, which allows plants to fix atmospheric NO and to use it for better growth and development. We identified non-symbiotic hemoglobin class 1 (AtGLB1) and class 2 (AtGLB2) as key proteins of the NO-fixation pathway. In an NO enriched environment NO-fixation is enhanced considerably in plants overexpressing AtGLB1 or AtGLB2 genes. NO uptake resulted in four-fold higher nitrate levels in these plants compared to NO-treated wild-type plants. Correspondingly, the growth parameters like rosettes size and weight, vegetative shoot thickness and also seed yield were 25%, 40%, 30%, and 20% higher, respectively, in the overexpression lines in comparison to wild-type plants. Our results highlight the existence of a NO-fixing pathway in plants. We demonstrated that plant non-symbiotic hemoglobin proteins can fix atmospheric NO and convert it to nitrate, which is further introduced into the N-metabolism. We assume that our results might provide new insights into the field of crop science research and that the NO-fixation capability might serve as a new economically important breeding trait for enhancing biomass, fruit, and seed production. Modifying this pathway might be a promising approach for better and more environment-friendly supply of nitrogen. For example crop plant hemoglobin proteins could be improved for their NO-fixing capability and their expression levels could be increased. WT-Arabidopsis thaliana plants were fumigated with Ambient NO and 3 ppm NO air in three completely independent biological experiments. Total RNA was isolated from four-week old rosette leaves of these plants to determine the gene expression signature of each samples using Agilent one-color microarray. Differences in the gene expression signatures between Ambient NO and 3 ppm NO treated samples were analyzed to see the effect of NO fumigation on the WT Arabidopsis plants at the transcript level.
Project description:To comprehensively investigate the effects of glutathione on the gene expression, the microarray analysis was performed in the glutathione-fed wild-type Arabidopsis thaliana. Wild-type Arabidopsis (ecotype Columbia-0) were fed with 1 mM oxidized glutathione (GSSG) and 2 mM reduced glutathione (GSH) for comparison at equal nitrogen equivalents. To examine the effects of glutathione other than nitrogen at equal nitrogen equivalents, plants were fed with 3 mM NH4NO3. Plants grown by water were used as a control.
Project description:affy_nitrogen_medicago - affy_nitrogen_medicago - Experiment has been designed to characterize the molecular expression patterns associated to a contrasted modification of the nitrogen status of the whole plant. The systemic effects of nitrogen status modifications are investigated and compared on non nodulated plant supplied with NO3, NH4 or nodulated plants (Sinorhizobium meliloti 2011) supplied with air. The root systems were separated in two compartments of unequal sizes (split root system). Two treatments were applied on the larger compartment in order to modulate the nitrogen status of the plant: for the S treatment, roots are supplied with nutrient solution containing 10 mM NH4NO3,, whereas for the C treatment, roots are supplied with nitrogen free medium. In the case of N2 fixing plants, N limitation was obtained by replacing air by a mixture of Ar and O2 80 per cent and 20 per cent. The effects of these treatments were investigated on roots of the minor compartment supplied continuously with either NO3 1 mM, NH4 1 mM or air (N2) and on the shoots. We were also interested in the molecular expression patterns associated to the roots deprived of N.-The root system of non-nodulated (NO3- and NH4+) or nodulated (N2) plants is split into two unequal parts and each one is installed in a separate compartment. For the S treatement, the major root part is supplied with NH4NO3 10 mM whereas the minor part is supplied with either NO3- 1mM, NH4+ 1mM or N2. For the C treatement, the major root part is supplied with nitrogen-free nutrient solution whereas the minor part is supplied with either NO3- 1mM, NH4plus 1mM or N2. Each treatement is four days long. Samples of roots of six biological types (NO3S, NO3C, NH4S, NH4C, N2S and N2C) were collected. Two biological repeats per biological types have been analyzed. The effect of the S and C treatments were investigated for each N sources by comparing Affymetrix transcriptomes (NO3C vs NO3S, NH4C vs NH4S, N2C vs N2S). Experiment Overall Design: 26 arrays - medicago
Project description:Root branching in response to changes in nitrogen status in the soil, is a dramatic example of the plant’s remarkable developmental plasticity. In recent work we investigated the genetic architecture of developmental plasticity, combining phenoclustering and genome-wide association studies in 96 Arabidopsis thaliana ecotypes with expression profiling in 7 ecotypes, to characterise natural variation in root architectural plasticity at the phenotypic, genetic, and transcriptional levels. This series contains the microarray expression data for 7 ecotypes that represent a range of root branching strategies. We used microarrays to detail the global programme of gene expression involved in the plants response to nitrogen in the root and identified distinct classes of up- and down-regulated genes in the seven different Arabidopsis ecotypes during this process.