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: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: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:Nitrogen (N) is an essential macronutrient for crops. Plants developed several responses to N fluctuations, thus optimizing the root architecture in response to N availability. Nitrate and ammonium are the main N inorganic forms taken up by plants and act as both nutrients and signals, affecting gene expression and plant development. In this study, RNA-sequencing was applied to gain comprehensive information on the pathways underlying the response of maize root, pre-treated in an N-deprived solution, to the provision of nitrate or ammonium. To assess the physiological response to these nutrients the shoot and root growth, the leaf pigment content and the amino acid amount in root and shoot were assessed. The analysis of the transcriptome shows that nitrate and ammonium regulate overlapping and distinct pathways, thus leading to different responses. NH4+ activates the response to stress, while NO3- acts as a negative regulator of transmembrane transport. Both the N-source repress genes related to the cytoskeleton and reactive oxygen species detoxification. Moreover, the presence of ammonium induces the accumulation of anthocyanins, while reduces biomass and chlorophyll and flavonoids accumulation. The profiles observed for hydrolysed and free amino acids highlighted common and distinct features in response to the two nitrogen forms.
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: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:Different forms of N can affect plant metabolism. Differences can be observed at physiological and transcriptional levels comparing maize 4-day-old maize seedlings tretaed for three days with three different N forms: protein hydrolysates (SICIT2000 Spa), inorganic nitrogen (NH4H2PO4) or a mixture of free amino acids.
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 â??Sâ?? treatment, one part was supplied with 10 mM NH4NO3 while the other part was supplied with a nitrogen-free nutrient solution. For the â??Lâ?? 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 18 arrays - Medicago