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Xu N, Cheng L, Kong Y, Chen G, Zhao L, Liu F. Functional analyses of the NRT2 family of nitrate transporters in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2024; 15:1351998. [PMID: 38501135 PMCID: PMC10944928 DOI: 10.3389/fpls.2024.1351998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 02/06/2024] [Indexed: 03/20/2024]
Abstract
Nitrogen is an essential macronutrient for plant growth and development. Nitrate is the major form of nitrogen acquired by most crops and also serves as a vital signaling molecule. Nitrate is absorbed from the soil into root cells usually by the low-affinity NRT1 NO3 - transporters and high-affinity NRT2 NO3 - transporters, with NRT2s serving to absorb NO3 - under NO3 -limiting conditions. Seven NRT2 members have been identified in Arabidopsis, and they have been shown to be involved in various biological processes. In this review, we summarize the spatiotemporal expression patterns, localization, and biotic and abiotic responses of these transporters with a focus on recent advances in the current understanding of the functions of the seven AtNRT2 genes. This review offers beneficial insight into the mechanisms by which plants adapt to changing environmental conditions and provides a theoretical basis for crop research in the near future.
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Affiliation(s)
- Na Xu
- School of Biological Science, Jining Medical University, Rizhao, Shandong, China
| | - Li Cheng
- School of Biological Science, Jining Medical University, Rizhao, Shandong, China
| | - Yuan Kong
- School of Biological Science, Jining Medical University, Rizhao, Shandong, China
| | - Guiling Chen
- School of Biological Science, Jining Medical University, Rizhao, Shandong, China
| | - Lufei Zhao
- Agricultural Science and Engineering School, Liaocheng University, Liaocheng, Shandong, China
| | - Fei Liu
- School of Biological Science, Jining Medical University, Rizhao, Shandong, China
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2
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LeKieffre C, Spero HJ, Fehrenbacher JS, Russell AD, Ren H, Geslin E, Meibom A. Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts. Proc Biol Sci 2020; 287:20200620. [PMID: 32546098 PMCID: PMC7329048 DOI: 10.1098/rspb.2020.0620] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate, and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM (transmission electron microscopy) coupled to NanoSIMS (nanoscale secondary ion mass spectrometry) isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based palaeoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
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Affiliation(s)
- Charlotte LeKieffre
- Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland.,UMR CNRS 6112 - LPG-BIAF, Université d'Angers, 49045 Angers Cedex, France
| | - Howard J Spero
- Department of Earth and Planetary Sciences, University of California Davis, Davis, CA 95616, USA
| | - Jennifer S Fehrenbacher
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Ann D Russell
- Department of Earth and Planetary Sciences, University of California Davis, Davis, CA 95616, USA
| | - Haojia Ren
- Department of Geosciences, National Taiwan University, Taipei, Taiwan
| | - Emmanuelle Geslin
- UMR CNRS 6112 - LPG-BIAF, Université d'Angers, 49045 Angers Cedex, France
| | - Anders Meibom
- Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland.,Center for Advanced Surface Analysis, Institute of Earth Sciences, University of Lausanne, Switzerland
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3
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Chen G, Li X, Chen Q, Wang L, Qi K, Yin H, Qiao X, Wang P, Zhang S, Wu J, Huang Z. Dynamic transcriptome analysis of root nitrate starvation and re-supply provides insights into nitrogen metabolism in pear (Pyrus bretschneideri). PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2018; 277:322-333. [PMID: 30466597 DOI: 10.1016/j.plantsci.2018.10.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 09/29/2018] [Accepted: 10/06/2018] [Indexed: 06/09/2023]
Abstract
Pear (Pyrus bretschneideri) is a popular fruit worldwide, but the irrational utilization of nitrogen as a fertilizer not only greatly affects the fruit' quality, but also wastes resources and results in serious environmental pollution. To better understand the molecular mechanism in pear responsible for the regulation of nitrate transport and assimilation, RNA-seq was performed on samples collected in response to nitrate treatments. Here, 10,273 differentially expressed genes were obtained and annotated into 49 GO terms, 45 clusters having co-expression trends that involved 18 KEGG-defined significantly overrepresented pathways. The KEGG pathways revealed that 15 unigenes, including one NRT gene, two NR genes, one NiR gene, two GDH genes, six GS genes and three GOGAT genes, were related to nitrogen metabolism and significantly differentially expressed in response to nitrate starvation and a nitrate re-supply treatment. Furthermore, 449 transcription factors belonging to 35 different families were identified during the nitrate treatments. The expression patterns of 14 randomly selected differentially expressed genes were validated by qRT-PCR. This study provides valuable resources for investigating the genetics of the nitrogen metabolic pathways and improving nitrogen utilization efficiency in pear.
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Affiliation(s)
- Guodong Chen
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Xiaolong Li
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Qian Chen
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Li Wang
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Kaijie Qi
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Hao Yin
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Xin Qiao
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Peng Wang
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Shaoling Zhang
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Juyou Wu
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.
| | - Zhi Huang
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.
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Berthelot H, Duhamel S, L'Helguen S, Maguer JF, Wang S, Cetinić I, Cassar N. NanoSIMS single cell analyses reveal the contrasting nitrogen sources for small phytoplankton. ISME JOURNAL 2018; 13:651-662. [PMID: 30323264 DOI: 10.1038/s41396-018-0285-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Revised: 07/09/2018] [Accepted: 09/08/2018] [Indexed: 12/16/2022]
Abstract
Nitrogen (N) is a limiting nutrient in vast regions of the world's oceans, yet the sources of N available to various phytoplankton groups remain poorly understood. In this study, we investigated inorganic carbon (C) fixation rates and nitrate (NO3-), ammonium (NH4+) and urea uptake rates at the single cell level in photosynthetic pico-eukaryotes (PPE) and the cyanobacteria Prochlorococcus and Synechococcus. To that end, we used dual 15N and 13C-labeled incubation assays coupled to flow cytometry cell sorting and nanoSIMS analysis on samples collected in the North Pacific Subtropical Gyre (NPSG) and in the California Current System (CCS). Based on these analyses, we found that photosynthetic growth rates (based on C fixation) of PPE were higher in the CCS than in the NSPG, while the opposite was observed for Prochlorococcus. Reduced forms of N (NH4+ and urea) accounted for the majority of N acquisition for all the groups studied. NO3- represented a reduced fraction of total N uptake in all groups but was higher in PPE (17.4 ± 11.2% on average) than in Prochlorococcus and Synechococcus (4.5 ± 6.5 and 2.9 ± 2.1% on average, respectively). This may in part explain the contrasting biogeography of these picoplankton groups. Moreover, single cell analyses reveal that cell-to-cell heterogeneity within picoplankton groups was significantly greater for NO3- uptake than for C fixation and NH4+ uptake. We hypothesize that cellular heterogeneity in NO3- uptake within groups facilitates adaptation to the fluctuating availability of NO3- in the environment.
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Affiliation(s)
- Hugo Berthelot
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 UBO/CNRS/IRD/IFREMER, Institut Universitaire Européen de la Mer (IUEM), Brest, France.
| | - Solange Duhamel
- Division of Biology and Paleo Environment, Lamont-Doherty Earth Observatory, PO Box 1000, 61 Route 9W, Palisades, NY, 10964, USA
| | - Stéphane L'Helguen
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 UBO/CNRS/IRD/IFREMER, Institut Universitaire Européen de la Mer (IUEM), Brest, France
| | - Jean-Francois Maguer
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 UBO/CNRS/IRD/IFREMER, Institut Universitaire Européen de la Mer (IUEM), Brest, France
| | - Seaver Wang
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA
| | - Ivona Cetinić
- NASA Goddard Space Flight Center, Ocean Ecology Laboratory, Code 616, Greenbelt, MD, USA.,GESTAR/Universities Space Research Association, Columbia, MD, USA
| | - Nicolas Cassar
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 UBO/CNRS/IRD/IFREMER, Institut Universitaire Européen de la Mer (IUEM), Brest, France. .,Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA.
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5
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Foflonker F, Ananyev G, Qiu H, Morrison A, Palenik B, Dismukes GC, Bhattacharya D. The unexpected extremophile: Tolerance to fluctuating salinity in the green alga Picochlorum. ALGAL RES 2016. [DOI: 10.1016/j.algal.2016.04.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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6
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Abstract
In response to demands for sustainable domestic fuel sources, research into biofuels has become increasingly important. Many challenges face biofuels in their effort to replace petroleum fuels, but rational strain engineering of algae and photosynthetic organisms offers a great deal of promise. For decades, mutations and stress responses in photosynthetic microbiota were seen to result in production of exciting high-energy fuel molecules, giving hope but minor capability for design. However, '-omics' techniques for visualizing entire cell processing has clarified biosynthesis and regulatory networks. Investigation into the promising production behaviors of the model organism C. reinhardtii and its mutants with these powerful techniques has improved predictability and understanding of the diverse, complex interactions within photosynthetic organisms. This new equipment has created an exciting new frontier for high-throughput, predictable engineering of photosynthetically produced carbon-neutral biofuels.
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Affiliation(s)
- Hanna R Aucoin
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO, 80401, USA
| | - Joseph Gardner
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO, 80401, USA
| | - Nanette R Boyle
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO, 80401, USA.
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7
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Sanz-Luque E, Chamizo-Ampudia A, Llamas A, Galvan A, Fernandez E. Understanding nitrate assimilation and its regulation in microalgae. FRONTIERS IN PLANT SCIENCE 2015; 6:899. [PMID: 26579149 PMCID: PMC4620153 DOI: 10.3389/fpls.2015.00899] [Citation(s) in RCA: 152] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 10/09/2015] [Indexed: 05/02/2023]
Abstract
Nitrate assimilation is a key process for nitrogen (N) acquisition in green microalgae. Among Chlorophyte algae, Chlamydomonas reinhardtii has resulted to be a good model system to unravel important facts of this process, and has provided important insights for agriculturally relevant plants. In this work, the recent findings on nitrate transport, nitrate reduction and the regulation of nitrate assimilation are presented in this and several other algae. Latest data have shown nitric oxide (NO) as an important signal molecule in the transcriptional and posttranslational regulation of nitrate reductase and inorganic N transport. Participation of regulatory genes and proteins in positive and negative signaling of the pathway and the mechanisms involved in the regulation of nitrate assimilation, as well as those involved in Molybdenum cofactor synthesis required to nitrate assimilation, are critically reviewed.
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Affiliation(s)
| | | | | | | | - Emilio Fernandez
- Department of Biochemistry and Molecular Biology, University of CordobaCordoba, Spain
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8
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Charrier A, Bérard JB, Bougaran G, Carrier G, Lukomska E, Schreiber N, Fournier F, Charrier AF, Rouxel C, Garnier M, Cadoret JP, Saint-Jean B. High-affinity nitrate/nitrite transporter genes (Nrt2) in Tisochrysis lutea: identification and expression analyses reveal some interesting specificities of Haptophyta microalgae. PHYSIOLOGIA PLANTARUM 2015; 154:572-90. [PMID: 25640753 DOI: 10.1111/ppl.12330] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 01/27/2015] [Accepted: 01/27/2015] [Indexed: 05/26/2023]
Abstract
Microalgae have a diversity of industrial applications such as feed, food ingredients, depuration processes and energy. However, microalgal production costs could be substantially improved by controlling nutrient intake. Accordingly, a better understanding of microalgal nitrogen metabolism is essential. Using in silico analysis from transcriptomic data concerning the microalgae Tisochrysis lutea, four genes encoding putative high-affinity nitrate/nitrite transporters (TlNrt2) were identified. Unlike most of the land plants and microalgae, cloning of genomic sequences and their alignment with complementary DNA (cDNA) sequences did not reveal the presence of introns in all TlNrt2 genes. The deduced TlNRT2 protein sequences showed similarities to NRT2 proteins of other phyla such as land plants and green algae. However, some interesting specificities only known among Haptophyta were also revealed, especially an additional sequence of 100 amino acids forming an atypical extracellular loop located between transmembrane domains 9 and 10 and the function of which remains to be elucidated. Analyses of individual TlNrt2 gene expression with different nitrogen sources and concentrations were performed. TlNrt2.1 and TlNrt2.3 were strongly induced by low NO3 (-) concentration and repressed by NH4 (+) substrate and were classified as inducible genes. TlNrt2.2 was characterized by a constitutive pattern whatever the substrate. Finally, TlNrt2.4 displayed an atypical response that was not reported earlier in literature. Interestingly, expression of TlNrt2.4 was rather related to internal nitrogen quota level than external nitrogen concentration. This first study on nitrogen metabolism of T. lutea opens avenues for future investigations on the function of these genes and their implication for industrial applications.
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Affiliation(s)
- Aurélie Charrier
- Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France
| | - Jean-Baptiste Bérard
- Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France
| | - Gaël Bougaran
- Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France
| | - Grégory Carrier
- Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France
| | - Ewa Lukomska
- Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France
| | - Nathalie Schreiber
- Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France
| | - Flora Fournier
- Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France
| | - Aurélie F Charrier
- Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France
| | - Catherine Rouxel
- Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France
| | - Matthieu Garnier
- Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France
| | - Jean-Paul Cadoret
- Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France
| | - Bruno Saint-Jean
- Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France
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9
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Sanz-Luque E, Ocaña-Calahorro F, de Montaigu A, Chamizo-Ampudia A, Llamas Á, Galván A, Fernández E. THB1, a truncated hemoglobin, modulates nitric oxide levels and nitrate reductase activity. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 81:467-79. [PMID: 25494936 DOI: 10.1111/tpj.12744] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 11/21/2014] [Accepted: 12/02/2014] [Indexed: 05/18/2023]
Abstract
Hemoglobins are ubiquitous proteins that sense, store and transport oxygen, but the physiological processes in which they are implicated is currently expanding. Recent examples of previously unknown hemoglobin functions, which include scavenging of the signaling molecule nitric oxide (NO), illustrate how the implication of hemoglobins in different cell signaling processes is only starting to be unraveled. The extent and diversity of the hemoglobin protein family suggest that hemoglobins have diverged and have potentially evolved specialized functions in certain organisms. A unique model organism to study this functional diversity at the cellular level is the green alga Chlamydomonas reinhardtii because, among other reasons, it contains an unusually high number of a particular type of hemoglobins known as truncated hemoglobins (THB1-THB12). Here, we reveal a cell signaling function for a truncated hemoglobin of Chlamydomonas that affects the nitrogen assimilation pathway by simultaneously modulating NO levels and nitrate reductase (NR) activity. First, we found that THB1 and THB2 expression is modulated by the nitrogen source and depends on NIT2, a transcription factor required for nitrate assimilation genes expression. Furthermore, THB1 is highly expressed in the presence of NO and is able to convert NO into nitrate in vitro. Finally, THB1 is maintained on its active and reduced form by NR, and in vivo lower expression of THB1 results in increased NR activity. Thus, THB1 plays a dual role in NO detoxification and in the modulation of NR activity. This mechanism can partly explain how NO inhibits NR post-translationally.
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Affiliation(s)
- Emanuel Sanz-Luque
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Córdoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, 14071, Córdoba, Spain
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10
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Gérin S, Mathy G, Franck F. Modeling the dependence of respiration and photosynthesis upon light, acetate, carbon dioxide, nitrate and ammonium in Chlamydomonas reinhardtii using design of experiments and multiple regression. BMC SYSTEMS BIOLOGY 2014; 8:96. [PMID: 25123231 PMCID: PMC4236732 DOI: 10.1186/s12918-014-0096-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 08/04/2014] [Indexed: 11/10/2022]
Abstract
BACKGROUND In photosynthetic organisms, the influence of light, carbon and inorganic nitrogen sources on the cellular bioenergetics has extensively been studied independently, but little information is available on the cumulative effects of these factors. Here, sequential statistical analyses based on design of experiments (DOE) coupled to standard least squares multiple regression have been undertaken to model the dependence of respiratory and photosynthetic responses (assessed by oxymetric and chlorophyll fluorescence measurements) upon the concomitant modulation of light intensity as well as acetate, CO₂, nitrate and ammonium concentrations in the culture medium of Chlamydomonas reinhardtii. The main goals of these analyses were to explain response variability (i.e. bioenergetic plasticity) and to characterize quantitatively the influence of the major explanatory factor(s). RESULTS For each response, 2 successive rounds of multiple regression coupled to one-way ANOVA F-tests have been undertaken to select the major explanatory factor(s) (1st-round) and mathematically simulate their influence (2nd-round). These analyses reveal that a maximal number of 3 environmental factors over 5 is sufficient to explain most of the response variability, and interestingly highlight quadratic effects and second-order interactions in some cases. In parallel, the predictive ability of the 2nd-round models has also been investigated by k-fold cross-validation and experimental validation tests on new random combinations of factors. These validation procedures tend to indicate that the 2nd-round models can also be used to predict the responses with an inherent deviation quantified by the analytical error of the models. CONCLUSIONS Altogether, the results of the 2 rounds of modeling provide an overview of the bioenergetic adaptations of C. reinhardtii to changing environmental conditions and point out promising tracks for future in-depth investigations of the molecular mechanisms underlying the present observations.
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Affiliation(s)
| | | | - Fabrice Franck
- Laboratory of Bioenergetics, Department of Life Sciences, Faculty of Sciences, University of Liege, Boulevard du Rectorat 27, Liege, 4000, Belgium.
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11
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Remacle C, Eppe G, Coosemans N, Fernandez E, Vigeolas H. Combined intracellular nitrate and NIT2 effects on storage carbohydrate metabolism in Chlamydomonas. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:23-33. [PMID: 24187418 PMCID: PMC3883280 DOI: 10.1093/jxb/ert339] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Microalgae are receiving increasing attention as alternative production systems for renewable energy such as biofuel. The photosynthetic alga Chlamydomonas reinhardtii is widely recognized as the model system to study all aspects of algal physiology, including the molecular mechanisms underlying the accumulation of starch and triacylglycerol (TAG), which are the precursors of biofuel. All of these pathways not only require a carbon (C) supply but also are strongly dependent on a source of nitrogen (N) to sustain optimal growth rate and biomass production. In order to gain a better understanding of the regulation of C and N metabolisms and the accumulation of storage carbohydrates, the effect of different N sources (NH4NO3 and ) on primary metabolism using various mutants impaired in either NIA1, NIT2 or both loci was performed by metabolic analyses. The data demonstrated that, using NH4NO3, nia1 strain displayed the most striking phenotype, including an inhibition of growth, accumulation of intracellular nitrate, and strong starch and TAG accumulation. The measurements of the different C and N intermediate levels (amino, organic, and fatty acids), together with the determination of acetate and remaining in the medium, clearly excluded the hypothesis of a slower and acetate assimilation in this mutant in the presence of NH4NO3. The results provide evidence of the implication of intracellular nitrate and NIT2 in the control of C partitioning into different storage carbohydrates under mixotrophic conditions in Chlamydomonas. The underlying mechanisms and implications for strategies to increase biomass yield and storage product composition in oleaginous algae are discussed.
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Affiliation(s)
- C. Remacle
- University of Liege, Institute of Botany, B22, Genetics of Microorganisms, 4000 Liege, Belgium
| | - G. Eppe
- University of Liege, Inorganic Analytical Chemistry, LSM-CART, Allée de la Chimie B6c, 4000 Liege, Belgium
| | - N. Coosemans
- University of Liege, Institute of Botany, B22, Genetics of Microorganisms, 4000 Liege, Belgium
| | - E. Fernandez
- Departamento de Bioquımica y Biologıa Molecular, Facultad de Ciencias, Universidad de Cordoba, Campus de Rabanales, 14071 Cordoba, Spain
| | - H. Vigeolas
- University of Liege, Institute of Botany, B22, Genetics of Microorganisms, 4000 Liege, Belgium
- * To whom correspondence should be addressed.
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12
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Gérin S, Mathy G, Blomme A, Franck F, Sluse FE. Plasticity of the mitoproteome to nitrogen sources (nitrate and ammonium) in Chlamydomonas reinhardtii: the logic of Aox1 gene localization. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:994-1003. [PMID: 20211595 DOI: 10.1016/j.bbabio.2010.02.034] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 02/25/2010] [Accepted: 02/26/2010] [Indexed: 11/24/2022]
Abstract
Nitrate and ammonium constitute primary inorganic nitrogen sources that can be incorporated into carbon skeletons in photosynthetic eukaryotes. In Chlamydomonas, previous studies and the present one showed that the mitochondrial AOX is up-regulated in nitrate-grown cells in comparison with ammonium-grown cells. In this work, we have performed a comparative proteomic analysis of the soluble mitochondrial proteome of Chlamydomonas cells growth either on nitrate or ammonium. Our results highlight important proteomics modifications mostly related to primary metabolism in cells grown on nitrate. We could note an up-regulation of some TCA cycle enzymes and a down-regulation of cytochrome c1 together with an up-regulation of l-arginine and purine catabolism enzymes and of ROS scavenging systems. Hence, in nitrate-grown cells, AOX may play a dual role: (1) lowering the ubiquinone pool reduction level and (2) permitting the export of mitochondrial reducing power under the form of malate for nitrate and nitrite reduction. This role of AOX in the mitochondrial plasticity makes logical the localization of Aox1 in a nitrate assimilation gene cluster.
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Affiliation(s)
- Stéphanie Gérin
- Laboratory of bioenergetics and cellular physiology, B6, Allée de la Chimie 3, 4000 Liège, Belgium
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13
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Rékangalt D, Pépin R, Verner MC, Debaud JC, Marmeisse R, Fraissinet-Tachet L. Expression of the nitrate transporter nrt2 gene from the symbiotic basidiomycete Hebeloma cylindrosporum is affected by host plant and carbon sources. MYCORRHIZA 2009; 19:143-148. [PMID: 19125303 DOI: 10.1007/s00572-008-0221-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Accepted: 12/10/2008] [Indexed: 05/27/2023]
Abstract
Although the function of the extramatrical mycelium of ectomycorrhizal fungi is considered essential for the acquisition of nitrogen by forest trees, gene regulation in this fungal compartment is poorly characterized. In this study, the expression of the nitrate transporter gene nrt2 from the ectomycorrhizal basidiomycete Hebeloma cylindrosporum was shown to be regulated by plant host and carbon sources. In the presence of a low fructose concentration, nrt2 expression could not be detected in the free-living mycelium but was high in the extramatrical symbiotic mycelium associated to the host plant Pinus pinaster. In the absence of nitrogen or in the presence of nitrate, high sugar concentrations in the medium were able to enhance nrt2 expression. Nevertheless, in the presence of high fructose concentration, high ammonium concentration still completely repressed nrt2 expression indicating that the nitrogen repression overrides sugar stimulation. This is the first report revealing an effect of host plant and of carbon sources on the expression of a fungal nitrate transporter-encoding gene.
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Affiliation(s)
- David Rékangalt
- Université de Lyon, 69622, Lyon, France
- CNRS, UMR5557, INRA, USC 1193, Ecologie Microbienne, Bât. Lwoff, Université Lyon 1, 43 boulevard du 11 novembre 1918, 69622, Villeurbanne Cedex, France
| | - Régis Pépin
- Université de Lyon, 69622, Lyon, France
- CNRS, UMR5557, INRA, USC 1193, Ecologie Microbienne, Bât. Lwoff, Université Lyon 1, 43 boulevard du 11 novembre 1918, 69622, Villeurbanne Cedex, France
| | - Marie-Christine Verner
- Université de Lyon, 69622, Lyon, France
- CNRS, UMR5557, INRA, USC 1193, Ecologie Microbienne, Bât. Lwoff, Université Lyon 1, 43 boulevard du 11 novembre 1918, 69622, Villeurbanne Cedex, France
| | - Jean-Claude Debaud
- Université de Lyon, 69622, Lyon, France
- CNRS, UMR5557, INRA, USC 1193, Ecologie Microbienne, Bât. Lwoff, Université Lyon 1, 43 boulevard du 11 novembre 1918, 69622, Villeurbanne Cedex, France
| | - Roland Marmeisse
- Université de Lyon, 69622, Lyon, France
- CNRS, UMR5557, INRA, USC 1193, Ecologie Microbienne, Bât. Lwoff, Université Lyon 1, 43 boulevard du 11 novembre 1918, 69622, Villeurbanne Cedex, France
| | - Laurence Fraissinet-Tachet
- Université de Lyon, 69622, Lyon, France.
- CNRS, UMR5557, INRA, USC 1193, Ecologie Microbienne, Bât. Lwoff, Université Lyon 1, 43 boulevard du 11 novembre 1918, 69622, Villeurbanne Cedex, France.
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14
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Affiliation(s)
- Emilio Fernandez
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Córdoba, Campus de Rabanales, Edif. Severo Ochoa, 14071-Córdoba, Spain.
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15
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Kakinuma M, Coury DA, Nakamoto C, Sakaguchi K, Amano H. Molecular analysis of physiological responses to changes in nitrogen in a marine macroalga, Porphyra yezoensis (Rhodophyta). Cell Biol Toxicol 2008; 24:629-39. [DOI: 10.1007/s10565-007-9053-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Accepted: 12/20/2007] [Indexed: 10/22/2022]
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16
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Slot JC, Hallstrom KN, Matheny PB, Hibbett DS. Diversification of NRT2 and the Origin of Its Fungal Homolog. Mol Biol Evol 2007; 24:1731-43. [PMID: 17513882 DOI: 10.1093/molbev/msm098] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigated the origin and diversification of the high-affinity nitrate transporter NRT2 in fungi and other eukaryotes using Bayesian and maximum parsimony methods. To assess the higher-level relationships and origins of NRT2 in eukaryotes, we analyzed 200 amino acid sequences from the Nitrate/Nitrite Porter (NNP) Family (to which NRT2 belongs), including 55 fungal, 41 viridiplantae (green plants), 11 heterokonts (stramenopiles), and 87 bacterial sequences. To assess evolution of NRT2 within fungi and other eukaryotes, we analyzed 116 amino acid sequences of NRT2 from 58 fungi, 40 viridiplantae (green plants), 1 rhodophyte, and 5 heterokonts, rooted with 12 bacterial sequences. Our results support a single origin of eukaryotic NRT2 from 1 of several clades of mostly proteobacterial NNP transporters. The phylogeny of bacterial NNP transporters does not directly correspond with bacterial taxonomy, apparently due to ancient duplications and/or horizontal gene transfer events. The distribution of NRT2 in the eukaryotes is patchy, but the NRT2 phylogeny nonetheless supports the monophyly of major groups such as viridiplantae, flowering plants, monocots, and eudicots, as well as fungi, ascomycetes, basidiomycetes, and agaric mushrooms. At least 1 secondary origin of eukaryotic NRT2 via horizontal transfer to the fungi is suggested, possibly from a heterokont donor. Our analyses also suggest that there has been a horizontal transfer of nrt2 from a basidiomycete fungus to an ascomycete fungus and reveal a duplication of nrt2 in the ectomycorrhizal mushroom genus, Hebeloma.
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Affiliation(s)
- Jason C Slot
- Department of Biology, Clark University, MA, USA.
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17
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Tsujimoto R, Yamazaki H, Maeda SI, Omata T. Distinct roles of nitrate and nitrite in regulation of expression of the nitrate transport genes in the moss Physcomitrella patens. PLANT & CELL PHYSIOLOGY 2007; 48:484-97. [PMID: 17289796 DOI: 10.1093/pcp/pcm019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Five NRT2 genes and three Nar2 genes, encoding putative high-affinity nitrate transporters, and the respective cDNAs were identified and characterized in Physcomitrella patens. The deduced moss NRT2 and NAR2 proteins were more similar to the corresponding proteins of higher plants than to those of the green alga Chlamydomonas reinhardtii. Expression of all the genes was inhibited by ammonium added to the medium. The regulation by ammonium was abolished by an inhibitor of glutamine synthetase, but the effect of this inhibitor was counteracted by an inhibitor of glutamate synthase. Negative correlation was observed between the glutamine content of protonemata and the transcript levels of PpNRT2 and PpNar2. These results indicated that glutamine is the signal for repression of the genes. All the genes except PpNRT2;5 showed transient expression stimulated by nitrate but not by nitrite, peaking at 2-4 h after the medium was deprived of ammonium. When the glutamine synthetase inhibitor was used to inhibit assimilation of the ammonium generated intracellularly from nitrate or nitrite, the second phase of activation of genes became manifest at approximately 8 h after the medium was deprived of ammonium. Surprisingly, both nitrate and nitrite stimulated gene expression at this stage. PpNRT2;5 was distinct from the other genes in that its expression is sharply induced by nitrite, is strictly dependent on nitrite or nitrate, and is much less susceptible to the feedback regulation, retaining a constant level in nitrate-containing medium. These results indicated that P. patens has multiple mechanisms for sensing nitrate and nitrite.
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Affiliation(s)
- Ryoma Tsujimoto
- Laboratory of Molecular Plant Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, 464-8601, Japan
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18
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Serrani F, Berardi E. The NII2 gene of Hansenula polymorpha is involved in nitrite assimilation. FEMS Yeast Res 2005; 5:999-1007. [PMID: 16144777 DOI: 10.1016/j.femsyr.2005.06.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Revised: 05/12/2005] [Accepted: 06/01/2005] [Indexed: 10/25/2022] Open
Abstract
To establish a basis for genetic and molecular studies of nitrite assimilation in the methylotrophic yeast Hansenula polymorpha, we isolated and characterised six nitrite-negative mutants still capable of growing on nitrate. Gene isolation work yielded the NII2 gene, encoding a membrane protein homologous to the Saccharomyces cerevisiae Pho86p. Sequence analysis revealed an ORF of 860 bp encoding a 286-amino-acid protein with a predicted molecular mass of 32.8 kDa. This protein is shorter than its S. cerevisiae homologue, and is predicted to lack an ER-retention signal. Cell suspension work revealed that the null mutant is unable to take up nitrite from the medium.
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Affiliation(s)
- Federica Serrani
- Laboratorio di Genetica Microbica, DiSA, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy
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19
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Baurain D, Dinant M, Coosemans N, Matagne RF. Regulation of the alternative oxidase Aox1 gene in Chlamydomonas reinhardtii. Role of the nitrogen source on the expression of a reporter gene under the control of the Aox1 promoter. PLANT PHYSIOLOGY 2003; 131:1418-30. [PMID: 12644691 PMCID: PMC166901 DOI: 10.1104/pp.013409] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2002] [Revised: 11/03/2002] [Accepted: 12/10/2002] [Indexed: 05/21/2023]
Abstract
In higher plants, various developmental and environmental conditions enhance expression of the alternative oxidase (AOX), whereas its induction in fungi is mainly dependent on cytochrome pathway restriction and triggering by reactive oxygen species. The AOX of the unicellular green alga Chlamydomonas reinhardtii is encoded by two different genes, the Aox1 gene being much more transcribed than Aox2. To analyze the transcriptional regulation of Aox1, we have fused its 1.4-kb promoter region to the promoterless arylsulfatase (Ars) reporter gene and measured ARS enzyme activities in transformants carrying the chimeric construct. We show that the Aox1 promoter is generally unresponsive to a number of known AOX inducers, including stress agents, respiratory inhibitors, and metabolites, possibly because the AOX activity is constitutively high in the alga. In contrast, the Aox1 expression is strongly dependent on the nitrogen source, being down-regulated by ammonium and stimulated by nitrate. Inactivation of nitrate reductase leads to a further increase of expression. The stimulation by nitrate also occurs at the AOX protein and respiratory levels. A deletion analysis of the Aox1 promoter region demonstrates that a short upstream segment (-253 to +59 with respect to the transcription start site) is sufficient to ensure gene expression and regulation, but that distal elements are required for full gene expression. The observed pattern of AOX regulation points to the possible interaction between chloroplast and mitochondria in relation to a potential increase of photogenerated ATP when nitrate is used as a nitrogen source.
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Affiliation(s)
- Denis Baurain
- Genetics of Microorganisms, Department of Life Sciences, B22, University of Liège, Sart Tilman, B-4000 Liège, Belgium
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20
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Llamas A, Igeño MI, Galván A, Fernández E. Nitrate signalling on the nitrate reductase gene promoter depends directly on the activity of the nitrate transport systems in Chlamydomonas. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2002; 30:261-71. [PMID: 12000675 DOI: 10.1046/j.1365-313x.2002.01281.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Nitrate signalling on the nitrate reductase (Nia1) gene promoter from Chlamydomonas reinhardtii has been studied by using a construct of the Nia1 promoter transcriptionally fused to the Chlamydomonas arylsulphatase gene as a reporter in strains bearing different sets of nitrate/nitrite transport genes. The high-affinity nitrate transport (HANT) system I is required for efficient signalling by nitrate, even at submicromolar concentrations of the anion. In addition, the autogenous regulation of nitrate reductase has been found to depend on the presence of system I. The low-affinity nitrate transport system III promoted signalling optimally on the promoter at millimolar nitrate concentrations. The HANT system IV, which is insensitive to ammonium and active at low CO2, allowed nitrate signalling at micromolar concentrations even in the presence of ammonium, suggesting that the balance of these two effectors controls Nia1 transcription. Our data indicate that nitrate signalling on the Nia1 gene promoter occurs intracellularly and depends on the activity of nitrate transporters.
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Affiliation(s)
- Angel Llamas
- Departamento de Bioquímica y Biología Molecular, Campus de Rabanales, Edificio Severo Ochoa, Universidad de Córdoba, 14071-Córdoba, Spain
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21
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Abstract
Chlamydomonas reinhardtii has been used as an experimental model organism for circadian rhythm research for more than 30 yr. Some of the physiological rhythms of this alga are well established, and several clock mutants have been isolated. The cloning of clock genes from these mutant strains by positional cloning is under way and should give new insights into the mechanism of the circadian clock. In a spectacular space experiment, the question of the existence of an endogenous clock vs. an exogenous mechanism has been studied in this organism. With the emergence of molecular analysis of circadian rhythms in plants in 1985, a circadian gene expression pattern of several nuclear and chloroplast genes was detected. Evidence is now accumulating that shows circadian control at the translational level. In addition, the gating of the cell cycle by the circadian clock has been analyzed. This review focuses on the different aspects of circadian rhythm research in C. reinhardtii over the past 30 yr. The suitability of Chlamydomonas as a model system in chronobiology research and the adaptive significance of the observed rhythms will be discussed.
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Affiliation(s)
- Ralf Werner
- University of Hamburg, Institute for General Botany and Botanical Garden, Department of Cell Biology, Germany.
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22
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Williams LE, Miller AJ. TRANSPORTERS RESPONSIBLE FOR THE UPTAKE AND PARTITIONING OF NITROGENOUS SOLUTES. ANNUAL REVIEW OF PLANT PHYSIOLOGY AND PLANT MOLECULAR BIOLOGY 2001; 52:659-688. [PMID: 11337412 DOI: 10.1146/annurev.arplant.52.1.659] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The acquisition and allocation of nitrogenous compounds are essential processes in plant growth and development. The huge economic and environmental costs resulting from the application of nitrogen fertilizers make this topic very important. A diverse array of transporters varying in their expression pattern and also in their affinity, specificity, and capacity for nitrogenous compounds has been identified. Now the future challenge is to define their individual contribution to nitrogen nutrition and signalling processes. Here we have reviewed recent advances in the identification and molecular characterization of these transporters, concentrating on mechanisms existing at the plasma membrane. The review focuses on nitrate, ammonium, and amino acid transporter familes, but we also briefly describe what is known at the molecular level about peptide transporters and a recently identified family implicated in the transport of purines and their derivatives.
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Affiliation(s)
- LE Williams
- School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton, SO16, 7PX, United Kingdom; e-mail: , Biochemistry and Physiology Department, IARC-Rothamsted, Harpenden, Herts AL5 2JQ, United Kingdom; e-mail:
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23
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Harris EH. CHLAMYDOMONAS AS A MODEL ORGANISM. ANNUAL REVIEW OF PLANT PHYSIOLOGY AND PLANT MOLECULAR BIOLOGY 2001; 52:363-406. [PMID: 11337403 DOI: 10.1146/annurev.arplant.52.1.363] [Citation(s) in RCA: 430] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The unicellular green alga Chlamydomonas offers a simple life cycle, easy isolation of mutants, and a growing array of tools and techniques for molecular genetic studies. Among the principal areas of current investigation using this model system are flagellar structure and function, genetics of basal bodies (centrioles), chloroplast biogenesis, photosynthesis, light perception, cell-cell recognition, and cell cycle control. A genome project has begun with compilation of expressed sequence tag data and gene expression studies and will lead to a complete genome sequence. Resources available to the research community include wild-type and mutant strains, plasmid constructs for transformation studies, and a comprehensive on-line database.
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Affiliation(s)
- Elizabeth H Harris
- Developmental, Cell and Molecular Biology Group, Biology Department, Duke University, Durham, North Carolina 27708-1000; e-mail:
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24
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Filleur S, Dorbe MF, Cerezo M, Orsel M, Granier F, Gojon A, Daniel-Vedele F. An arabidopsis T-DNA mutant affected in Nrt2 genes is impaired in nitrate uptake. FEBS Lett 2001; 489:220-4. [PMID: 11165253 DOI: 10.1016/s0014-5793(01)02096-8] [Citation(s) in RCA: 181] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Expression analyses of Nrt2 plant genes have shown a strict correlation with root nitrate influx mediated by the high-affinity transport system (HATS). The precise assignment of NRT2 protein function has not yet been possible due to the absence of heterologous expression studies as well as loss of function mutants in higher plants. Using a reverse genetic approach, we isolated an Arabidopsis thaliana knock-out mutant where the T-DNA insertion led to the complete deletion of the AtNrt2.1 gene together with the deletion of the 3' region of the AtNrt2.2 gene. This mutant is impaired in the HATS, without being modified in the low-affinity system. Moreover, the de-regulated expression of a Nicotiana plumbaginifolia Nrt2 gene restored the mutant nitrate influx to that of the wild-type. These results demonstrate that plant NRT2 proteins do have a role in HATS.
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Affiliation(s)
- S Filleur
- Unité de la Nutrition Azotée des Plantes, INRA, Versailles, France
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25
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Machín F, Perdomo G, Pérez MD, Brito N, Siverio JM. Evidence for multiple nitrate uptake systems in the yeast Hansenula polymorpha. FEMS Microbiol Lett 2001; 194:171-4. [PMID: 11164303 DOI: 10.1111/j.1574-6968.2001.tb09464.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Hansenula polymorpha mutants disrupted in the high-affinity nitrate transporter gene (YNT1) are still able to grow in nitrate. To detect the nitrate transporter(s) responsible for this growth a strain containing disruption of the nitrate assimilation gene cluster and expressing nitrate reductase gene (YNR1) under the control of H. polymorpha MOX1 (methanol oxidase) promoter was used (FM31 strain). In this strain nitrate taken up is transformed into nitrite by nitrate reductase and excreted to the medium where it is easily detected. Nitrate uptake which is neither induced by nitrate nor repressed by reduced nitrogen sources was detected in the FM31 strain. Likewise, nitrate uptake detected in the strain FM31 is independent of both Ynt1p and Yna1p and is not affected by ammonium, glutamine or chlorate. The inhibition of nitrite extrusion by extracellular nitrite suggests that the nitrate uptake system shown in the FM31 strain could also be involved in nitrite uptake.
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Affiliation(s)
- F Machín
- Departamento de Bioquímica y Biología Molecular, Grupo del Metabolismo del Nitrógeno-Consejo Superior de Investigaciones Científicas, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Canary Islands, Spain
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26
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Quesada A, Fernández E. Involvement of chloroplast and mitochondria redox valves in nitrate assimilation. TRENDS IN PLANT SCIENCE 2000; 5:463-464. [PMID: 11185544 DOI: 10.1016/s1360-1385(00)01770-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Affiliation(s)
- A Quesada
- Deprtmento de Bioquímica y Biologia Molecular, Universidad de Córdoba, Spain.
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27
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Abstract
To cope with low nutrient availability in nature, organisms have evolved inducible systems that enable them to scavenge and efficiently utilize the limiting nutrient. Furthermore, organisms must have the capacity to adjust their rate of metabolism and make specific alterations in metabolic pathways that favor survival when the potential for cell growth and division is reduced. In this article I will focus on the acclimation of Chlamydomonas reinhardtii, a unicellular, eukaryotic green alga to conditions of nitrogen, sulfur and phosphorus deprivation. This organism has a distinguished history as a model for classical genetic analyses, but it has recently been developed for exploitation using an array of molecular and genomic tools. The application of these tools to the analyses of nutrient limitation responses (and other biological processes) is revealing mechanisms that enable Chlamydomonas to survive harsh environmental conditions and establishing relationships between the responses of this morphologically simple, photosynthetic eukaryote and those of both nonphotosynthetic organisms and vascular plants.
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28
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Forde BG. Nitrate transporters in plants: structure, function and regulation. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1465:219-35. [PMID: 10748256 DOI: 10.1016/s0005-2736(00)00140-1] [Citation(s) in RCA: 262] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Physiological studies have established that plants acquire their NO(-3) from the soil through the combined activities of a set of high- and low-affinity NO(-3) transport systems, with the influx of NO(-3) being driven by the H(+) gradient across the plasma membrane. Some of these NO(-3) transport systems are constitutively expressed, while others are NO(-3)-inducible and subject to negative feedback regulation by the products of NO(-3) assimilation. Here we review recent progress in the characterisation of the two families of NO(-3) transporters that have so far been identified in plants, their structure and their regulation, and consider the evidence for their roles in NO(-3) acquisition. We also discuss what is currently known about the genetic basis of NO(-3) induction and feedback repression of the NO(-3) transport and assimilatory pathway in higher plants.
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Affiliation(s)
- B G Forde
- Biochemistry and Physiology Department, IACR-Rothamsted, Harpenden, UK.
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29
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Navarro MT, Guerra E, Fernández E, Galván A. Nitrite reductase mutants as an approach to understanding nitrate assimilation in Chlamydomonas reinhardtii. PLANT PHYSIOLOGY 2000; 122:283-90. [PMID: 10631272 PMCID: PMC58867 DOI: 10.1104/pp.122.1.283] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/1999] [Accepted: 09/24/1999] [Indexed: 05/18/2023]
Abstract
We constructed mutant strains lacking the nitrite reductase (NR) gene in Chlamydomonas reinhardtii. Two types of NR mutants were obtained, which either have or lack the high-affinity nitrate transporter (Nrt2;1, Nrt2;2, and Nar2) genes. None of these mutants overexpressed nitrate assimilation gene transcripts nor NR activity in nitrogen-free medium, in contrast to NR mutants. This finding confirms the previous role proposed for NR on its own regulation (autoregulation) and on the other genes for nitrate assimilation in C. reinhardtii. In addition, the NR mutants were used to study nitrate transporters from nitrite excretion. At high CO(2), only strains carrying the above high-affinity nitrate transporter genes excreted stoichiometric amounts of nitrite from 100 microM nitrate in the medium. A double mutant, deficient in both the high-affinity nitrate transporter genes and NR, excreted nitrite at high CO(2) only when nitrate was present at mM concentrations. This suggests that there exists a low-affinity nitrate transporter that might correspond to the nitrate/nitrite transport system III. Moreover, under low CO(2) conditions, the double mutant excreted nitrite from nitrate at micromolar concentrations by a transporter with the properties of the nitrate/nitrite transport system IV.
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Affiliation(s)
- M T Navarro
- Departamento de Bioquímica y Biología Molecular and Instituto Andaluz de Biotecnología, Avda. San Alberto Magno, Facultad de Ciencias, Universidad de Córdoba, 14071-Córdoba, Spain
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30
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Rexach J, Montero B, Fernández E, Galván A. Differential regulation of the high affinity nitrite transport systems III and IV in Chlamydomonas reinhardtii. J Biol Chem 1999; 274:27801-6. [PMID: 10488125 DOI: 10.1074/jbc.274.39.27801] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two high affinity nitrite transporters have been identified in Chlamydomonas reinhardtii. They have been named system III and system IV and shown to be differentially regulated by nitrogen and carbon supply. System III was induced under high CO(2) and required a micromolar nitrate signal for optimal expression, was inhibited by ammonium, and was not affected by either chloride or the chloride channel inhibitor 5-nitro-2-(3-phenylpropylamino)benzoic acid. System IV was induced optimally under limiting CO(2) and did not require nitrate signal, was inhibited by chloride and 5-nitro-2-(3-phenylpropylamino)benzoic acid, but was not affected by ammonium. Two transcripts that shared the expression pattern of systems III and IV activities were detected with an Nrt2;3 gene probe. In addition, a mutant defective in both the activity of system III and the expression of Nrt2;3 gene has been isolated. Genetic crosses and in vivo complementation studies indicate that this mutant is defective in a locus that is closely linked to the regulatory gene Nit2.
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Affiliation(s)
- J Rexach
- Departamento de Bioquímica y Biología Molecular, Avenida San Alberto Magno s/n, Facultad de Ciencias, Universidad de Córdoba and Instituto Andaluz de Biotecnología, 14071 Córdoba, Spain
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31
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Abstract
Recent research shows that signals derived from nitrate are involved in triggering widespread changes in gene expression, resulting in a reprogramming of nitrogen and carbon metabolism to facilitate the uptake and assimilation of nitrate, and to initiate accompanying changes in carbon metabolism. These nitrate-derived signals interact with signals generated further downstream in nitrogen metabolism, and in carbon metabolism. Signals derived from internal and external nitrate also adjust root growth and architecture to the physiological state of the plant, and the distribution of nitrate in the environment.
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Affiliation(s)
- M Stitt
- Botanisches Institut, In Neuenheimer Feld 360, 69120, Heidelberg, Germany.
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32
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Daniel-Vedele F, Filleur S, Caboche M. Nitrate transport: a key step in nitrate assimilation. CURRENT OPINION IN PLANT BIOLOGY 1998; 1:235-9. [PMID: 10066586 DOI: 10.1016/s1369-5266(98)80110-6] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The nitrate assimilation pathway has been the matter of intensive research during the past decade. Many genes involved in low and high affinity nitrate uptake have been identified in fungi, algae and, more recently, in plants. The plant genes so far isolated are transcriptionally regulated; their inducibility by nitrate seems to be a common feature, shared by their homologs in fungi and algae. A number of questions remain to be elucidated regarding the physiological roles of these transporters and the regulation of their expression.
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Affiliation(s)
- F Daniel-Vedele
- Laboratoire de Biologie Cellulaire, INRA, Route de St Cyr, 78026 Versailles Cedex, France.
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