Transcriptome analysis of Arabidopsis wild-type and NRT1.1-knockout mutant seedlings grown under 10 mM ammonium as sole nitrogen source
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ABSTRACT: High levels of ammonium as the sole nitrogen source impairs plant growth, i.e. ammonium toxicity, the primary cause of which remains to be determined. To obtain a clue about the toxic mechanism, we compared genome-wide gene expression between the wild-type (Col) and NRT1.1-knockout mutant (chl1-5, nrt1.1) seedlings growing in media containing toxic levels of ammonium as the sole nitrogen source.
Project description:The conversion of nitrate to ammonium, known as nitrate reduction, consumes large amounts of reductants in plants. Previous studies have observed that mitochondrial alternative oxidase (AOX) is upregulated under conditions of limited nitrate reduction, such as low or no nitrate availability, or when ammonium serves as the sole nitrogen (N) source. Electron transfer from ubiquinone to AOX bypasses the proton-pumping complexes III and IV, thereby consuming reductants efficiently. Therefore, the upregulation of AOX under conditions of limited nitrate reduction may help dissipate excessive reductants and mitigate oxidative stress. However, firm evidence supporting this hypothesis is lacking due to the absence of experimental systems capable of directly analyzing the relationship between nitrate reduction and AOX. To address this gap, we developed a novel culturing system that allows for the manipulation of nitrate reduction and AOX activities separately, without inducing N starvation, ammonium toxicity, or disrupting the nitrate signal. Using this system, we investigated genome-wide gene expression with RNA-seq to gain insight into the relationship between AOX and nitrate reduction.
Project description:Abundant ammonium nutrition impairs plant growth, i.e. ammonium toxicity, the primary cause of which remains to be determined. To obtain a clue about the toxic mechanism, we performed microarray experiments and compared the expression of genes responsive to toxic levels of ammonium between the wild-type (Col) and an ammonium-insensitive mutant (ami2) shoots growing in media containing 10 mM ammonium.
Project description:In plants, nitrate is suggested to act as an indicator of nitrogen (N) status that modulates N responses under steady-state conditions. Our preceding study suggested that shoot nitrate accumulation alone represses expression of N starvation-inducible genes in shoots and roots. Notably, we observed that shoot nitrate accumulation was accompanied by increases in shoot expression of ISOPENTENYL TRANSFERASE 3 (IPT3) and shoot levels of N6-(Δ2-isopentenyl) adenine (iP)-type CK. IPT3 expression is localized primarily in phloem companion cells, and iP-type CKs, which are synthesized by IPT3, are phloem-mobile. Hence, both local and systemic responses to shoot nitrate status may be regulated by IPT3-synthesized iP-type CKs. Thus, the present study aims to dissect the local/systemic responses to shoot nitrate status and their dependence on shoot IPT3. To achieve this, we developed a novel experimental system to manipulate nitrate levels and IPT3 expression in a shoot-specific manner using grafted plants derived from the plants lacking nitrate reductase and/or IPT3. Using shoots and roots from the grafted plants, RNA-seq analysis was performed.
Project description:Nitrogen limitation is a major regulator to initiate lipid overproduction in oleaginous fungi. To examine the influence of nitrogen starvation, chemiostat cultures of R. toruloides in defined media with abundant ammonium (MM) or minute ammonium (MM-N) were performed to obtain steady-state samples. Then Illumina's digital gene expression (DGE) technology was used for high-throughput transcriptome profiling of these samples. Two samples cultured in minimum media with abundant ammonium (MM) or minute ammonium (MM-N)
Project description:CHL1 is one of major nitrate transporters responsible for nitrate uptake and some studies suggest that it may be also play a role in regulating the nitrate response, its influence was analyzed in a global transcriptome study using Affymetrix ATH1 array. Experiment Overall Design: Three biological replicates of 10-day-old Arabidopsis root tissue from wild-type and chl1-5 plants were performed to explore differences in gene expression between the wild-type and chl1-5 mutants exposed to 25 mM nitrate for 0h (T0) or 0.5h (T0.5) using Affymetrix ATH1 microarray.
Project description:Comparison of Azotobacter vinelandii str. DJ transcriptomes using either ammonium or dinitrogen as sole nitrogen source. Transcriptomes from cells in early stages of nitrogenase derepression (10 min and 30 min) and at the peak of nitrogenase derepression (4 hours) were compared against the corresponding controls from cells using ammonium as nitrogen source. Kinetics of the nitrogen fixation (nif) genes expression profiles resemble those previously published (Poza-Carrion, 2013; doi: 10.1128/jb.00942-13).
Project description:Nitrogen is major nutrient for plant growth. Two forms for inorganic nitrogen are available for plant, ammonium and nitrate. External status of them affects largely plant growth and production. Generally, root is a sole organ to uptake nitrogen. Hence, identifying regulatory genes depend on nitrogen status in roots is important to improve sustainable production or rice. To isolate the candidate gene, array experiments were performed. Consequently, we isolated genes which showed marked accumulation in deficient and sufficient concentrations of ammonium in roots.
Project description:Biological treatments to degrade cyanide are a powerful technology for cyanide removal from industrial wastewaters. It has been previously demonstrated that the alkaliphilic bacterium Pseudomonas pseudoalcaligenes CECT5344 is able to use free cyanide and several metal-cyanide complexes as the sole nitrogen source. In this work, the strain CECT5344 has been used for detoxification of the different chemical forms of cyanide that are present in alkaline wastewaters from the jewelry industry. This liquid residue also contains large concentrations of metals like iron, copper and zinc, making this wastewater even more toxic. To elucidate the molecular mechanisms involved in the bioremediation process, a quantitative sRNA sequencing analysis has been carried out in P. pseudoalcaligenes CECT5344 cells grown with the jewelry residue, free cyanide and ammonium as sole nitrogen sources.
Project description:This study is measuring the steady-state levels of mRNA in wild-type Caulobacter crescentus grown in M2 defined medium containing either ammonium or nitrate as the sole nitrogen source.
Project description:Identification of the earliest transcriptional responses of adult Arabidopsis plant roots towards N-deprivation. Hydroponically grown Plants (35 days old) were 5 days adapted to nitrate or ammonium,respectively, as sole N-source to detect N-form specific transcripts. 24 Samples: 2 Pre-Treatments (5 Day adaptation to 3mM Ammonium/Nitrate) x 3 sampling time-points (0min, 15 min, 180 min) x 3 independent replications per time-point + 6 additional controls (2 x 15min, 1x 180min per Pre-Treatment)