Biological nitrogen fixation maintains C/N balance and photosynthesis at elevated CO2
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ABSTRACT:
PROVIDER: PRJNA1020873 | ENA |
REPOSITORIES: ENA
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Project description:To investigate the effect that biological nitrogen fixation will have on plant responses to nitrogen dose at elevated CO2, alfalfa (Medicago sativa) lines were grown at three nitrogen doses and ambient or elevated CO2. Four lines were used in the study, two lines that can form nodules capable of fixing nitrogen (effective lines) and two lines that can not form nodules capable of nitrogen fixation (ineffective lines). The ineffective lines are the result of a complementary mutation in the same gene.
2024-02-26 | GSE244008 | GEO
Project description:Elevated CO2 (E[CO2]) improves the biomass and yield when combined with water-stress in C4 plants. Although several studies described the molecular response of the C4 plant Sorghum bicolor during drought exposure, none reported its combinatorial effect with E[CO2] in the roots. We decided to perform a molecular analysis using green prop roots, the portion of the radicular system photosynthetically active and more sensible to drought. Whole-transcriptome analysis identified 394 up- and 1,471 down-regulated genes. Among the E[CO2] induced pathways, photosynthesis stood out. Carbon fixation, phenylpropanoid, phenolic compounds, and fatty acid biosynthesis-related pathways were repressed. Protein family analysis showed induction of chlorophyll a-b binding protein family, and repression of glutathione-related enzymes. Protein-protein interaction networks exhibited well-defined clusters, including genes related to cell organization and biogenesis, oxireduction process, and photosynthesis being induced. The findings suggest that the E[CO2] mitigates the water deficit by antioxidant and osmoregulation activity, as well as by accumulation of sugaralcohols in the green prop roots, which may be responsible by the increase in biomass together with the cell proliferation. The higher carbon uptake explains the increase in photosynthetic and primary metabolism activities. Our data revealed that green prop roots present an intriguing metabolism under water deficit and E[CO2], showing its crucial role in the drought tolerance acquisition in a predicted future global atmosphere.
2021-06-30 | GSE179109 | GEO
Project description:Physiological and molecular evidences have shown earlier that low CO2 might have been a major driving force during the evolution of C4 photosynthesis, not only being a selection pressure but also as a signaling agent. However, a mechanistic linkage between low CO2 and C4 emergence is missing. In this study, using transcriptomics study in model plant Arabidopsis thaliana, we demonstrated that under long-term low CO2 treatments, the up-regulation of C4 related genes were linked to the up-regulation of genes involved in photorespiration, nitrogen assimilation and glycolysis. Plants under low CO2 also showed altered d13C. The carbonic anhydrase (CA), phosphoenolpyruvate carboxylase (PEPC), malate dehydrogenase (MDH), glutamine oxoglutarate aminotransferase (GS-GOGAT), which are required to reassimilate ammonia, were up-regulated under low CO2. Furthermore, under low CO2, genes involved in PEP regeneration from glycolysis were up-regulated while pyruvate orthophosphate dikinase (PPDK) was down-regulated, suggesting a route of PEP regeneration from glycolysis. All these results suggested that under long-term low CO2 treatment, the selection pressure to recapture the released ammonia from the increased photorespiration might have promoted the evolution of mechanisms for generation PEP from glycolysis and enhancement of enzymes catalyzing formation of oxaloacetate, one intermediate which can accept ammonia residue. These adjustments in metabolism provide a mechanistic linkage between low CO2 and evolution of C4 photosynthesis.
2016-12-31 | GSE64547 | GEO
Project description:Carbon fixation plays a central role in determining cellular redox poise, increasingly understood to be a key parameter in cyanobacterial physiology. In the cyanobacterium Prochlorococcus--—the most abundant phototroph in the oligotrophic oceans--—the carbon-concentrating mechanism (CCM) is reduced to the bare essentials. Given the ability of Prochlorococcus populations to grow under a wide range of oxygen concentrations in the ocean, we wondered how carbon and oxygen physiology intersect in this minimal phototroph. We monitored genome-wide transcription in cells shocked with acute limitation of CO2, O2, or both. O2 limitation produced much smaller transcriptional changes than the broad suppression seen under CO2 limitation and CO2/O2 co-limitation. Strikingly, the transcriptional responses evoked by both CO2 limitation conditions were initially similar to that previously seen in high light stress, but at later timepoints we observed O2-dependent recovery of photosynthesis-related transcripts. These results suggest that oxygen plays a protective role in Prochlorococcus when carbon fixation is not a sufficient sink for light energy.
2015-04-15 | GSE65684 | GEO
Project description:Regulation of CO2 fixation in cyanobacteria is important both for the organism and the global carbon balance. Here we show that phosphoketolase in Synechococcus elongatus PCC7942 (SeXPK) possesses a distinct ATP sensing mechanism, which upon ATP drops, allows SeXPK to divert precursors of the RuBisCO substrate away from the Calvin-Benson-Bassham (CBB) cycle. Deleting the SeXPK gene increased CO2 fixation particularly during light-dark transitions. In high-density cultures, the xpk strain showed a 60% increase in carbon fixation, and unexpectedly resulted in sucrose secretion without any pathway engineering. Using cryo-EM analysis, we discovered that these functions were enabled by a unique allosteric regulatory site involving two subunits jointly binding two ATP, which constantly suppresses the activity of SeXPK until the ATP level drops. This magnesium-independent ATP allosteric site is present in many species across all three domains of life, where it may also play important regulatory functions.
2023-08-08 | GSE227397 | GEO
Project description:To study whether and how soil nitrogen conditions affect the ecological effects of long-term elevated CO2 on microbial community and soil ecoprocess, here we investigated soil microbial community in a grassland ecosystem subjected to ambient CO2 (aCO2, 368 ppm), elevated CO2 (eCO2, 560 ppm), ambient nitrogen deposition (aN) or elevated nitrogen deposition (eN) treatments for a decade. Under the aN condition, a majority of microbial function genes, as measured by GeoChip 4.0, were increased in relative abundance or remained unchanged by eCO2. Under the eN condition, most of functional genes associated with carbon, nitrogen and sulfur cycling, energy processes, organic remediation and stress responses were decreased or remained unchanged by eCO2, while genes associated with antibiotics and metal resistance were increased. The eCO2 effects on fungi and archaea were largely similar under both nitrogen conditions, but differed substantially for bacteria. Coupling of microbial carbon or nitrogen cycling genes, represented by positive percentage and density of gene interaction in association networks, was higher under the aN condition. In accordance, changes of soil CO2 flux, net N mineralization, ammonification and nitrification was higher under the aN condition. Collectively, these results demonstrated that eCO2 effects are contingent on nitrogen conditions, underscoring the difficulty toward predictive modeling of soil ecosystem and ecoprocesses under future climate scenarios and necessitating more detailed studies.
2015-04-03 | GSE67531 | GEO
Project description:Carbon fixation plays a central role in determining cellular redox poise, increasingly understood to be a key parameter in cyanobacterial physiology. In the cyanobacterium Prochlorococcus--—the most abundant phototroph in the oligotrophic oceans--—the carbon-concentrating mechanism (CCM) is reduced to the bare essentials. Given the ability of Prochlorococcus populations to grow under a wide range of oxygen concentrations in the ocean, we wondered how carbon and oxygen physiology intersect in this minimal phototroph. We monitored genome-wide transcription in cells shocked with acute limitation of CO2, O2, or both. O2 limitation produced much smaller transcriptional changes than the broad suppression seen under CO2 limitation and CO2/O2 co-limitation. Strikingly, the transcriptional responses evoked by both CO2 limitation conditions were initially similar to that previously seen in high light stress, but at later timepoints we observed O2-dependent recovery of photosynthesis-related transcripts. These results suggest that oxygen plays a protective role in Prochlorococcus when carbon fixation is not a sufficient sink for light energy. Two biological replicates of timecourses under four conditions: medium bubbled with air (control) or three experimental gases (low CO2; low O2; or low CO2 and low O2)
2015-04-15 | E-GEOD-65684 | biostudies-arrayexpress
Project description:Thioredoxins play an essential role in regulating enzyme activity upon response to environmental changes, especially in photosynthetic organisms. These are crucial for the regulation of metabolism in cyanobacteria, but the key central processes redox-regulated remain to be determined. Physiological, metabolic and transcriptomic characterization of a conditional mutant of the essential trxA gene in Synechocystis (STXA2) revealed that reduced TrxA levels alter cell morphology and enter in a dormant-like state. TrxA depletion in the STXA2 strain inhibited protein synthesis and led to changes in amino acid pools and nitrogen/carbon reserve polymers, accompanied by oxidation of the Elongation Factor EF-Tu. Transcriptomic analysis of TrxA depletion in STXA2 showed a robust transcriptional response. Genes that responded negatively were grouped in a large cluster and were directly related to photosynthesis, ATP synthesis and CO2 fixation, while genes that responded positively were grouped in different clusters and related to respiratory electron transport, carotenoids synthesis, amino acid metabolism and protein degradation, among others. Regulation of cyanobacterial metabolism is complex and fine-tuned, our results link TrxA to the switch from anabolic to maintenance metabolism in cyanobacteria, regulating carbon and nitrogen balance.
2023-09-24 | GSE243518 | GEO
Project description:The effects of elevated CO2 (hypercapnia) on organisms are not well known, nor are the molecular pathways by which organisms sense CO2. We have performed microarray analysis on Drosophila in order to develop a genetic model for better understanding the effects of CO2.
2009-09-30 | GSE17444 | GEO