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Liu LM, Sun CY, Xi YC, Lu XH, Yong CW, Li SQ, Sun QW, Wang XW, Mao YZ, Chen W, Jiang HB. A global transcriptional activator involved in the iron homeostasis in cyanobacteria. SCIENCE ADVANCES 2024; 10:eadl6428. [PMID: 38959319 PMCID: PMC11221513 DOI: 10.1126/sciadv.adl6428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 05/30/2024] [Indexed: 07/05/2024]
Abstract
Cyanobacteria use a series of adaptation strategies and a complicated regulatory network to maintain intracellular iron (Fe) homeostasis. Here, a global activator named IutR has been identified through three-dimensional chromosome organization and transcriptome analysis in a model cyanobacterium Synechocystis sp. PCC 6803. Inactivation of all three homologous IutR-encoding genes resulted in an impaired tolerance of Synechocystis to Fe deficiency and loss of the responses of Fe uptake-related genes to Fe-deplete conditions. Protein-promoter interaction assays confirmed the direct binding of IutR with the promoters of genes related to Fe uptake, and chromatin immunoprecipitation sequencing analysis further revealed that in addition to Fe uptake, IutR could regulate many other physiological processes involved in intracellular Fe homeostasis. These results proved that IutR is an important transcriptional activator, which is essential for cyanobacteria to induce Fe-deficiency response genes. This study provides in-depth insights into the complicated Fe-deficient signaling network and the molecular mechanism of cyanobacteria adaptation to Fe-deficient environments.
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Affiliation(s)
- Ling-Mei Liu
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
- School of Life Sciences, Central China Normal University, Wuhan, Hubei, China
| | - Chuan-Yu Sun
- School of Life Sciences, Central China Normal University, Wuhan, Hubei, China
| | - Yi-Cao Xi
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
| | - Xiao-Hui Lu
- School of Life Sciences, Central China Normal University, Wuhan, Hubei, China
| | - Cheng-Wen Yong
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
| | - Shuang-Qing Li
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
| | - Qiao-Wei Sun
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
| | - Xin-Wei Wang
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
| | - You-Zhi Mao
- Wuhan Frasergen Bioinformatics Co. Ltd., Wuhan, Hubei, China
| | - Weizhong Chen
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
| | - Hai-Bo Jiang
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
- School of Life Sciences, Central China Normal University, Wuhan, Hubei, China
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, Guangdong, China
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2
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Dellisanti W, Zhang Q, Ferrier-Pagès C, Kühl M. Contrasting effects of increasing dissolved iron on photosynthesis and O 2 availability in the gastric cavity of two Mediterranean corals. PeerJ 2024; 12:e17259. [PMID: 38699194 PMCID: PMC11064864 DOI: 10.7717/peerj.17259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 03/27/2024] [Indexed: 05/05/2024] Open
Abstract
Iron (Fe) plays a fundamental role in coral symbiosis, supporting photosynthesis, respiration, and many important enzymatic reactions. However, the extent to which corals are limited by Fe and their metabolic responses to inorganic Fe enrichment remains to be understood. We used respirometry, variable chlorophyll fluorescence, and O2 microsensors to investigate the impact of increasing Fe(III) concentrations (20, 50, and 100 nM) on the photosynthetic capacity of two Mediterranean coral species, Cladocora caespitosa and Oculina patagonica. While the bioavailability of inorganic Fe can rapidly decrease, we nevertheless observed significant physiological effects at all Fe concentrations. In C. caespitosa, exposure to 50 nM Fe(III) increased rates of respiration and photosynthesis, while the relative electron transport rate (rETR(II)) decreased at higher Fe(III) exposure (100 nM). In contrast, O. patagonica reduced respiration, photosynthesis rates, and maximum PSII quantum yield (Fv/Fm) across all iron enrichments. Both corals exhibited increased hypoxia (<50 µmol O2 L-1) within their gastric cavity at night when exposed to 50 and 100 nM Fe(III), leading to increased polyp contraction time and reduced O2 exchange with the surrounding water. Our results indicate that C. caespitosa, but not O. patagonica, might be limited in Fe for achieving maximal photosynthetic efficiency. Understanding the multifaceted role of iron in corals' health and their response to environmental change is crucial for effective coral conservation.
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Affiliation(s)
- Walter Dellisanti
- Department of Biology, Marine Biology Section, University of Copenhagen, Helsingør, Denmark
| | - Qingfeng Zhang
- Department of Biology, Marine Biology Section, University of Copenhagen, Helsingør, Denmark
| | - Christine Ferrier-Pagès
- Coral Ecophysiology Laboratory, Center Scientifique de Monaco, Principality of Monaco, Monaco
| | - Michael Kühl
- Department of Biology, Marine Biology Section, University of Copenhagen, Helsingør, Denmark
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3
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Chen Z, Yuan ZW, Luo WX, Wu X, Pan JL, Yin YQ, Shao HC, Xu K, Li WZ, Hu YL, Wang Z, Gao KS, Chen XW. UV-A radiation increases biomass yield by enhancing energy flow and carbon assimilation in the edible cyanobacterium Nostoc sphaeroides. Appl Environ Microbiol 2024; 90:e0211023. [PMID: 38391210 PMCID: PMC10952460 DOI: 10.1128/aem.02110-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 01/25/2024] [Indexed: 02/24/2024] Open
Abstract
Ultraviolet (UV) A radiation (315-400 nm) is the predominant component of solar UV radiation that reaches the Earth's surface. However, the underlying mechanisms of the positive effects of UV-A on photosynthetic organisms have not yet been elucidated. In this study, we investigated the effects of UV-A radiation on the growth, photosynthetic ability, and metabolome of the edible cyanobacterium Nostoc sphaeroides. Exposures to 5-15 W m-2 (15-46 µmol photons m-2 s-1) UV-A and 4.35 W m-2 (20 μmol photons m-2 s-1) visible light for 16 days significantly increased the growth rate and biomass production of N. sphaeroides cells by 18%-30% and 15%-56%, respectively, compared to the non-UV-A-acclimated cells. Additionally, the UV-A-acclimated cells exhibited a 1.8-fold increase in the cellular nicotinamide adenine dinucleotide phosphate (NADP) pool with an increase in photosynthetic capacity (58%), photosynthetic efficiency (24%), QA re-oxidation, photosystem I abundance, and cyclic electron flow (87%), which further led to an increase in light-induced NADPH generation (31%) and ATP content (83%). Moreover, the UV-A-acclimated cells showed a 2.3-fold increase in ribulose-1,5-bisphosphate carboxylase/oxygenase activity, indicating an increase in their carbon-fixing capacity. Gas chromatography-mass spectrometry-based metabolomics further revealed that UV-A radiation upregulated the energy-storing carbon metabolism, as evidenced by the enhanced accumulation of sugars, fatty acids, and citrate in the UV-A-acclimated cells. Therefore, our results demonstrate that UV-A radiation enhances energy flow and carbon assimilation in the cyanobacterium N. sphaeroides.IMPORTANCEUltraviolet (UV) radiation exerts harmful effects on photo-autotrophs; however, several studies demonstrated the positive effects of UV radiation, especially UV-A radiation (315-400 nm), on primary productivity. Therefore, understanding the underlying mechanisms associated with the promotive effects of UV-A radiation on primary productivity can facilitate the application of UV-A for CO2 sequestration and lead to the advancement of photobiological sciences. In this study, we used the cyanobacterium Nostoc sphaeroides, which has an over 1,700-year history of human use as food and medicine, to explore its photosynthetic acclimation response to UV-A radiation. As per our knowledge, this is the first study to demonstrate that UV-A radiation increases the biomass yield of N. sphaeroides by enhancing energy flow and carbon assimilation. Our findings provide novel insights into UV-A-mediated photosynthetic acclimation and provide a scientific basis for the application of UV-A radiation for optimizing light absorption capacity and enhancing CO2 sequestration in the frame of a future CO2 neutral, circular, and sustainable bioeconomy.
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Affiliation(s)
- Zhen Chen
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Zu-Wen Yuan
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Wei-Xin Luo
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Xun Wu
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Jin-Long Pan
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Yong-Qi Yin
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Hai-Chen Shao
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Kui Xu
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Wei-Zhi Li
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Yuan-Liang Hu
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
| | - Zhe Wang
- Hubei Key Laboratory of Quality and Safety of Traditional Chinese Medicine Health Food, Jing Brand Co., Ltd., Daye, Hubei, China
| | - Kun-Shan Gao
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, China
| | - Xiong-Wen Chen
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, China
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Sunda WG, Marchetti A. Proton-pumping rhodopsins promote the growth and survival of phytoplankton in a highly variable ocean. THE ISME JOURNAL 2024; 18:wrae079. [PMID: 38696358 PMCID: PMC11104272 DOI: 10.1093/ismejo/wrae079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 04/23/2024] [Accepted: 04/29/2024] [Indexed: 05/04/2024]
Affiliation(s)
- William G Sunda
- Department of Earth, Marine, and Environmental Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States
| | - Adrian Marchetti
- Department of Earth, Marine, and Environmental Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States
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5
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Zhang Q, Charles PD, Bendif EM, Hester SS, Mohammad S, Rickaby REM. Stimulating and toxic effect of chromium on growth and photosynthesis of a marine chlorophyte. THE NEW PHYTOLOGIST 2024; 241:676-686. [PMID: 37974482 DOI: 10.1111/nph.19376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Accepted: 10/09/2023] [Indexed: 11/19/2023]
Abstract
Marine phytoplankton can interchange trace metals in various biochemical functions, particularly under metal-limiting conditions. Here, we investigate the stimulating and toxicity effect of chromium (Cr) on a marine Chlorophyceae Osetreococcus tauri under Fe-replete and Fe-deficient conditions. We determined the growth, photosynthesis, and proteome expressions of Osetreococcus tauri cultured under different Cr and Fe concentrations. In Fe-replete conditions, the presence of Cr(VI) stimulated significantly the growth rate and the maximum yield of photochemistry of photosystem II (Fv /Fm ) of the phytoplankton, while the functional absorption cross-section of photosystem II (σPSII ) did not change. Minor additions of Cr(VI) partially rescued phytoplankton growth under Fe-limited conditions. Proteomic analysis of this alga grown in Fe-replete normal and Fe-replete with Cr addition media (10 μM Cr) showed that the presence of Cr significantly decreased the expression of phosphate-transporting proteins and photosynthetic proteins, while increasing the expression of proteins related to carbon assimilation. Cr can stimulate the growth and photosynthesis of O. tauri, but the effects are dependent on both the Cr(VI) concentration and the availability of Fe. The proteomic results further suggest that Cr(VI) addition might significantly increase starch production and carbon fixation.
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Affiliation(s)
- Qiong Zhang
- Department of Ocean Science and Center for Ocean Research in Hong Kong and Macau (CORE), The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, 999077, China
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Tang Qi Road, Zhuhai, 519000, China
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, UK
| | - Philip D Charles
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - El Mahdi Bendif
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, UK
- Institut des sciences de la mer de Rimouski (ISMER), Université du Québec à Rimouski, Rimouski, G5L 3A1, QC, Canada
| | - Svenja S Hester
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Shabaz Mohammad
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Rosalind E M Rickaby
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, UK
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6
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Browning TJ, Al-Hashem AA, Achterberg EP, Carvalho PC, Catry P, Matthiopoulos J, Miller JAO, Wakefield ED. The role of seabird guano in maintaining North Atlantic summertime productivity. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 897:165309. [PMID: 37406699 DOI: 10.1016/j.scitotenv.2023.165309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 06/29/2023] [Accepted: 07/02/2023] [Indexed: 07/07/2023]
Abstract
Nutrients supplied via seabird guano increase primary production in some coastal ecosystems. A similar process may occur in the open ocean. To investigate this directly, we first measured bulk and leachable nutrient concentrations in guano sampled in the North Atlantic. We found that guano was strongly enriched in phosphorus, which was released as phosphate in solution. Nitrogen release was dominated by reduced forms (ammonium and urea) whilst release of nitrate was relatively low. A range of trace elements, including the micronutrient iron, were released. Using in-situ bioassays, we then showed that supply of fresh guano to ambient seawater increases phytoplankton biomass and photochemical efficiencies. Based on these results, modelled seabird distributions, and known defecation rates, we estimate that on annual scales guano is a minor source of nutrients for the surface North Atlantic. However, on shorter timescales in late spring/summer it could be much more important: Estimates of upper-level depositions of phosphorus by seabirds were three orders of magnitude higher than modelled aerosol deposition and comparable to diffusion from deeper waters.
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Affiliation(s)
- Thomas J Browning
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Kiel, Germany.
| | - Ali A Al-Hashem
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Kiel, Germany
| | - Eric P Achterberg
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Kiel, Germany
| | - Paloma C Carvalho
- Freshwater Institute, Fisheries and Oceans Canada, Winnipeg, MB R3T 2N6, Canada
| | - Paulo Catry
- Marine and Environmental Sciences Centre (MARE) / Aquatic Research Network (ARNET), ISPA - Instituto Universitário, Rua Jardim do Tabaco 34, 1149-041 Lisbon, Portugal
| | - Jason Matthiopoulos
- School of Biodiversity One Health and Veterinary Medicine, University of Glasgow, United Kingdom
| | - Julie A O Miller
- School of Biodiversity One Health and Veterinary Medicine, University of Glasgow, United Kingdom
| | - Ewan D Wakefield
- School of Biodiversity One Health and Veterinary Medicine, University of Glasgow, United Kingdom; Department of Geography, Durham University, Lower Mountjoy, South Road, Durham, DH1 3LE, UK
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7
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Balaguer J, Koch F, Flintrop CM, Völkner C, Iversen MH, Trimborn S. Iron and manganese availability drives primary production and carbon export in the Weddell Sea. Curr Biol 2023; 33:4405-4414.e4. [PMID: 37769661 DOI: 10.1016/j.cub.2023.08.086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 07/17/2023] [Accepted: 08/30/2023] [Indexed: 10/03/2023]
Abstract
Next to iron (Fe), recent phytoplankton-enrichment experiments identified manganese (Mn) to (co-)limit Southern Ocean phytoplankton biomass and species composition. Since taxonomic diversity affects aggregation time and sinking rate, the efficiency of the biological carbon pump is directly affected by community structure. However, the impact of FeMn co-limitation on Antarctic primary production, community composition, and the subsequent export of carbon to depth requires more investigation. In situ samplings of 6 stations in the understudied southern Weddell Sea revealed that surface Fe and Mn concentrations, primary production, and carbon export rates were all low, suggesting a FeMn co-limited phytoplankton community. An Fe and Mn addition experiment examined how changes in the species composition drive the aggregation capability of a natural phytoplankton community. Primary production rates were highest when Fe and Mn were added together, due to an increased abundance of the colonial prymnesiophyte Phaeocystis antarctica. Although the community remained diatom dominated, the increase in Phaeocystis abundance led to highly carbon-enriched aggregates and a 4-fold increase in the carbon export potential compared to the control, whereas it only doubled in the Fe treatment. Based on the outcome of the FeMn-enrichment experiment, this region may suffer from FeMn co-limitation. As the Weddell Sea represents one of the most productive Antarctic marginal ice zones, our findings highlight that in response to greater Fe and Mn supply, changes in plankton community composition and primary production can have a disproportionally larger effect on the carbon export potential.
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Affiliation(s)
- Jenna Balaguer
- Marine Botany, University of Bremen, Bremen 28359, Germany; Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven 25570, Germany.
| | - Florian Koch
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven 25570, Germany
| | - Clara M Flintrop
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven 25570, Germany; The Fredy & Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel; Interuniversity Institute for Marine Sciences, Eilat 88103, Israel
| | - Christian Völkner
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven 25570, Germany
| | - Morten H Iversen
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven 25570, Germany; MARUM Center for Marine Environmental Sciences, University of Bremen, Bremen 28359, Germany
| | - Scarlett Trimborn
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven 25570, Germany
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8
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Browning TJ, Saito MA, Garaba SP, Wang X, Achterberg EP, Moore CM, Engel A, Mcllvin MR, Moran D, Voss D, Zielinski O, Tagliabue A. Persistent equatorial Pacific iron limitation under ENSO forcing. Nature 2023; 621:330-335. [PMID: 37587345 PMCID: PMC10499608 DOI: 10.1038/s41586-023-06439-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 07/14/2023] [Indexed: 08/18/2023]
Abstract
Projected responses of ocean net primary productivity to climate change are highly uncertain1. Models suggest that the climate sensitivity of phytoplankton nutrient limitation in the low-latitude Pacific Ocean plays a crucial role1-3, but this is poorly constrained by observations4. Here we show that changes in physical forcing drove coherent fluctuations in the strength of equatorial Pacific iron limitation through multiple El Niño/Southern Oscillation (ENSO) cycles, but that this was overestimated twofold by a state-of-the-art climate model. Our assessment was enabled by first using a combination of field nutrient-addition experiments, proteomics and above-water hyperspectral radiometry to show that phytoplankton physiological responses to iron limitation led to approximately threefold changes in chlorophyll-normalized phytoplankton fluorescence. We then exploited the >18-year satellite fluorescence record to quantify climate-induced nutrient limitation variability. Such synoptic constraints provide a powerful approach for benchmarking the realism of model projections of net primary productivity to climate changes.
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Affiliation(s)
- Thomas J Browning
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
| | - Mak A Saito
- Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Shungudzemwoyo P Garaba
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany
| | - Xuechao Wang
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Eric P Achterberg
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - C Mark Moore
- School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, UK
| | - Anja Engel
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | | | - Dawn Moran
- Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Daniela Voss
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany
| | - Oliver Zielinski
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany
- German Research Center for Artificial Intelligence (DFKI), Oldenburg, Germany
- Leibniz Institute for Baltic Sea Research Warnemünde (IOW), Warnemünde, Germany
| | - Alessandro Tagliabue
- Department of Earth, Ocean, Ecological Sciences, University of Liverpool, Liverpool, UK
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9
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Browning TJ, Moore CM. Global analysis of ocean phytoplankton nutrient limitation reveals high prevalence of co-limitation. Nat Commun 2023; 14:5014. [PMID: 37591895 PMCID: PMC10435517 DOI: 10.1038/s41467-023-40774-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 08/09/2023] [Indexed: 08/19/2023] Open
Abstract
Nutrient availability limits phytoplankton growth throughout much of the global ocean. Here we synthesize available experimental data to identify three dominant nutrient limitation regimes: nitrogen is limiting in the stratified subtropical gyres and in the summertime Arctic Ocean, iron is most commonly limiting in upwelling regions, and both nutrients are frequently co-limiting in regions in between the nitrogen and iron limited systems. Manganese can be co-limiting with iron in parts of the Southern Ocean, whilst phosphate and cobalt can be co-/serially limiting in some settings. Overall, an analysis of experimental responses showed that phytoplankton net growth can be significantly enhanced through increasing the number of different nutrients supplied, regardless of latitude, temperature, or trophic status, implying surface seawaters are often approaching nutrient co-limitation. Assessments of nutrient deficiency based on seawater nutrient concentrations and nutrient stress diagnosed via molecular biomarkers showed good agreement with experimentally-assessed nutrient limitation, validating conceptual and theoretical links between nutrient stoichiometry and microbial ecophysiology.
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Affiliation(s)
- Thomas J Browning
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Research, Kiel, 24148, Germany.
| | - C Mark Moore
- School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, SO14 3ZH, UK.
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10
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Anugerahanti P, Tagliabue A. Process controlling iron-manganese regulation of the Southern Ocean biological carbon pump. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2023; 381:20220065. [PMID: 37150202 PMCID: PMC10164462 DOI: 10.1098/rsta.2022.0065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 03/07/2023] [Indexed: 05/09/2023]
Abstract
Iron (Fe) is a key limiting nutrient driving the biological carbon pump and is routinely represented in global ocean biogeochemical models. However, in the Southern Ocean, the potential role for other micronutrients has not received the same attention. For example, although manganese (Mn) is essential to photosynthetic oxygen production and combating oxidative stress, it is not included in ocean models and a clear understanding of its interaction with Fe in the region is lacking. This is especially important for the Southern Ocean because both Mn and Fe are strongly depleted. We use a hierarchical modelling approach to explore how the physiological traits associated with Fe and Mn contribute to driving the footprint of micronutrient stress across different phytoplankton functional types (PFTs). We find that PFT responses are driven by physiological traits associated with their physiological requirements and acclimation to environmental conditions. Southern Ocean-specific adaptations to prevailing low Fe, such as large photosynthetic antenna sizes, are of major significance for the regional biological carbon pump. Other traits more strongly linked to Mn, such as dealing with oxidative stress, may become more important under a changing Fe supply regime. This article is part of a discussion meeting issue 'Heat and carbon uptake in the Southern Ocean: the state of the art and future priorities'.
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Affiliation(s)
- Prima Anugerahanti
- Department of Earth, University of Liverpool, Ocean, and Ecological Sciences, 4 Brownlow Street, Liverpool L69 3GP, UK
| | - Alessandro Tagliabue
- Department of Earth, University of Liverpool, Ocean, and Ecological Sciences, 4 Brownlow Street, Liverpool L69 3GP, UK
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11
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Oura M, Papry RI, Kato Y, Nakamura Y, Kosugi C, Hong WK, Mashio AS, Hasegawa H. A new evaluation system of iron bioavailability in seaweed. MARINE ENVIRONMENTAL RESEARCH 2023; 187:105947. [PMID: 36934509 DOI: 10.1016/j.marenvres.2023.105947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 03/01/2023] [Accepted: 03/11/2023] [Indexed: 06/18/2023]
Abstract
In marine ecosystems, the avid binding of iron (Fe) to organic ligands influences Fe bioavailability in seaweed. This study aimed to elucidate Fe's biological availability to seaweed and develop a simple and rapid bioassay method as a new evaluation system. Undaria pinnatifida was used as a model seaweed species and the actual seaweed samples were collected using the 0.5 m × 0.5 m quadrat from the Mashike Bay area of Hokkaido, Japan. Chlorophyll fluorescence measurements were utilized as an index to evaluate the biological -effectiveness of Fe and compared with the results of culture tests based on growth. The effect of Fe content on media, pre-culture, concentrations and types of chelating and reducing agents in clearing solutions, cleaning time, Fe removal effect, and resistance to seaweed were systematically optimized to obtain the maximum efficacy of the washing solution. A bioassay was developed to evaluate the Fe environment by combining chlorophyll fluorescence measurements. The findings suggest that the tolerance of seaweeds to the wash solution is strongly influenced by the concentrations of the chelating and reducing agents than their types. Washing with 0.02 M Ti-Citrate/EDTA solution for 80 s was the most effective in terms of maximum Fe removal with minimum cell damage. The application of pre-culture and chemical pre-treatment methods under Fe deficiency to the culture strain confirmed the maximum reproducibility in the culture test. Finally, the developed method was applied to actual seaweed samples and was found to be applicable to many seaweed species. However, the method was less robust for some seaweed species and depended on the seaweed growth stage.
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Affiliation(s)
- Masahiro Oura
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan
| | - Rimana Islam Papry
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan; Department of Environmental Science, College of Agricultural Sciences, IUBAT- International University of Business Agriculture and Technology, Sector 10, Uttara, Dhaka, 1230, Bangladesh.
| | - Yusuke Kato
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan
| | - Yuki Nakamura
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan
| | - Chika Kosugi
- Advanced Technology Research Laboratories, Nippon Steel Corporation, 20-1 Shintomi, Futtsu City, Chiba, 293-8511, Japan
| | - Wong Kuo Hong
- Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan
| | - Asami Suzuki Mashio
- Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan
| | - Hiroshi Hasegawa
- Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan.
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12
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Ryan-Keogh TJ, Thomalla SJ, Monteiro PMS, Tagliabue A. Multidecadal trend of increasing iron stress in Southern Ocean phytoplankton. Science 2023; 379:834-840. [PMID: 36821685 DOI: 10.1126/science.abl5237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
Southern Ocean primary productivity is principally controlled by adjustments in light and iron limitation, but the spatial and temporal determinants of iron availability, accessibility, and demand are poorly constrained, which hinders accurate long-term projections. We present a multidecadal record of phytoplankton photophysiology between 1996 and 2022 from historical in situ datasets collected by Biogeochemical Argo (BGC-Argo) floats and ship-based platforms. We find a significant multidecadal trend in irradiance-normalized nonphotochemical quenching due to increasing iron stress, with concomitant declines in regional net primary production. The observed trend of increasing iron stress results from changing Southern Ocean mixed-layer physics as well as complex biological and chemical feedback that is indicative of important ongoing changes to the Southern Ocean carbon cycle.
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Affiliation(s)
- Thomas J Ryan-Keogh
- Southern Ocean Carbon-Climate Observatory, CSIR, Cape Town 7700, South Africa
| | - Sandy J Thomalla
- Southern Ocean Carbon-Climate Observatory, CSIR, Cape Town 7700, South Africa
- Marine and Antarctic Research for Innovation and Sustainability, University of Cape Town, Cape Town 7700, South Africa
| | - Pedro M S Monteiro
- Southern Ocean Carbon-Climate Observatory, CSIR, Cape Town 7700, South Africa
- School for Climate Studies, Stellenbosch University, Stellenbosch 7602, South Africa
| | - Alessandro Tagliabue
- Department of Earth, Ocean and Ecological Sciences, School of Environmental Sciences, University of Liverpool, Liverpool L69 3GP, UK
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13
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Nagao R, Kato K, Hamaguchi T, Ueno Y, Tsuboshita N, Shimizu S, Furutani M, Ehira S, Nakajima Y, Kawakami K, Suzuki T, Dohmae N, Akimoto S, Yonekura K, Shen JR. Structure of a monomeric photosystem I core associated with iron-stress-induced-A proteins from Anabaena sp. PCC 7120. Nat Commun 2023; 14:920. [PMID: 36805598 PMCID: PMC9938196 DOI: 10.1038/s41467-023-36504-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 02/03/2023] [Indexed: 02/19/2023] Open
Abstract
Iron-stress-induced-A proteins (IsiAs) are expressed in cyanobacteria under iron-deficient conditions. The cyanobacterium Anabaena sp. PCC 7120 has four isiA genes; however, their binding property and functional roles in PSI are still missing. We analyzed a cryo-electron microscopy structure of a PSI-IsiA supercomplex isolated from Anabaena grown under an iron-deficient condition. The PSI-IsiA structure contains six IsiA subunits associated with the PsaA side of a PSI core monomer. Three of the six IsiA subunits were identified as IsiA1 and IsiA2. The PSI-IsiA structure lacks a PsaL subunit; instead, a C-terminal domain of IsiA2 occupies the position of PsaL, which inhibits the oligomerization of PSI, leading to the formation of a PSI monomer. Furthermore, excitation-energy transfer from IsiAs to PSI appeared with a time constant of 55 ps. These findings provide insights into both the molecular assembly of the Anabaena IsiA family and the functional roles of IsiAs.
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Affiliation(s)
- Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan. .,Faculty of Agriculture, Shizuoka University, Shizuoka, 422-8529, Japan.
| | - Koji Kato
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan.,Structural Biology Division, Japan Synchrotron Radiation Research Institute (JASRI), Hyogo, 679-5198, Japan
| | - Tasuku Hamaguchi
- Biostructural Mechanism Laboratory, RIKEN SPring-8 Center, Hyogo, 679-5148, Japan.,Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Miyagi, 980-8577, Japan
| | - Yoshifumi Ueno
- Graduate School of Science, Kobe University, Hyogo, 657-8501, Japan.,Institute of Arts and Science, Tokyo University of Science, Tokyo, 162-8601, Japan
| | - Naoki Tsuboshita
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Shota Shimizu
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Miyu Furutani
- Graduate School of Science, Kobe University, Hyogo, 657-8501, Japan
| | - Shigeki Ehira
- Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, Tokyo, 192-0397, Japan
| | - Yoshiki Nakajima
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Keisuke Kawakami
- Biostructural Mechanism Laboratory, RIKEN SPring-8 Center, Hyogo, 679-5148, Japan
| | - Takehiro Suzuki
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Saitama, 351-0198, Japan
| | - Naoshi Dohmae
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Saitama, 351-0198, Japan
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, Hyogo, 657-8501, Japan.
| | - Koji Yonekura
- Biostructural Mechanism Laboratory, RIKEN SPring-8 Center, Hyogo, 679-5148, Japan. .,Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Miyagi, 980-8577, Japan. .,Advanced Electron Microscope Development Unit, RIKEN-JEOL Collaboration Center, RIKEN Baton Zone Program, Hyogo, 679-5148, Japan.
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan.
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14
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Hawco NJ, Tagliabue A, Twining BS. Manganese Limitation of Phytoplankton Physiology and Productivity in the Southern Ocean. GLOBAL BIOGEOCHEMICAL CYCLES 2022; 36:e2022GB007382. [PMID: 37034112 PMCID: PMC10078217 DOI: 10.1029/2022gb007382] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 10/05/2022] [Accepted: 10/07/2022] [Indexed: 05/24/2023]
Abstract
Although iron and light are understood to regulate the Southern Ocean biological carbon pump, observations have also indicated a possible role for manganese. Low concentrations in Southern Ocean surface waters suggest manganese limitation is possible, but its spatial extent remains poorly constrained and direct manganese limitation of the marine carbon cycle has been neglected by ocean models. Here, using available observations, we develop a new global biogeochemical model and find that phytoplankton in over half of the Southern Ocean cannot attain maximal growth rates because of manganese deficiency. Manganese limitation is most extensive in austral spring and depends on phytoplankton traits related to the size of photosynthetic antennae and the inhibition of manganese uptake by high zinc concentrations in Antarctic waters. Importantly, manganese limitation expands under the increased iron supply of past glacial periods, reducing the response of the biological carbon pump. Overall, these model experiments describe a mosaic of controls on Southern Ocean productivity that emerge from the interplay of light, iron, manganese and zinc, shaping the evolution of Antarctic phytoplankton since the opening of the Drake Passage.
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Affiliation(s)
- Nicholas J. Hawco
- Department of OceanographyUniversity of Hawaiʻi at MānoaHonoluluHIUSA
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15
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Nef C, Madoui MA, Pelletier É, Bowler C. Whole-genome scanning reveals environmental selection mechanisms that shape diversity in populations of the epipelagic diatom Chaetoceros. PLoS Biol 2022; 20:e3001893. [PMID: 36441816 PMCID: PMC9731442 DOI: 10.1371/journal.pbio.3001893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 12/08/2022] [Accepted: 10/27/2022] [Indexed: 11/30/2022] Open
Abstract
Diatoms form a diverse and abundant group of photosynthetic protists that are essential players in marine ecosystems. However, the microevolutionary structure of their populations remains poorly understood, particularly in polar regions. Exploring how closely related diatoms adapt to different environments is essential given their short generation times, which may allow rapid adaptations, and their prevalence in marine regions dramatically impacted by climate change, such as the Arctic and Southern Oceans. Here, we address genetic diversity patterns in Chaetoceros, the most abundant diatom genus and one of the most diverse, using 11 metagenome-assembled genomes (MAGs) reconstructed from Tara Oceans metagenomes. Genome-resolved metagenomics on these MAGs confirmed a prevalent distribution of Chaetoceros in the Arctic Ocean with lower dispersal in the Pacific and Southern Oceans as well as in the Mediterranean Sea. Single-nucleotide variants identified within the different MAG populations allowed us to draw a landscape of Chaetoceros genetic diversity and revealed an elevated genetic structure in some Arctic Ocean populations. Gene flow patterns of closely related Chaetoceros populations seemed to correlate with distinct abiotic factors rather than with geographic distance. We found clear positive selection of genes involved in nutrient availability responses, in particular for iron (e.g., ISIP2a, flavodoxin), silicate, and phosphate (e.g., polyamine synthase), that were further supported by analysis of Chaetoceros transcriptomes. Altogether, these results highlight the importance of environmental selection in shaping diatom diversity patterns and provide new insights into their metapopulation genomics through the integration of metagenomic and environmental data.
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Affiliation(s)
- Charlotte Nef
- Institut de Biologie de l’École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, Paris, France
- Research Federation for the study of Global Ocean Systems Ecology and Evolution, FR2022/Tara Oceans, Paris, France
| | - Mohammed-Amin Madoui
- Service d’Etude des Prions et des Infections Atypiques (SEPIA), Institut François Jacob, Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Université Paris Saclay, Fontenay-aux-Roses, France
- Équipe Écologie Évolutive, UMR CNRS 6282 BioGéoSciences, Université de Bourgogne Franche-Comté, Dijon, 21000, France
| | - Éric Pelletier
- Research Federation for the study of Global Ocean Systems Ecology and Evolution, FR2022/Tara Oceans, Paris, France
- Metabolic Genomics, Genoscope, Institut de Biologie François-Jacob, CEA, CNRS, Université Evry, Université Paris Saclay, Evry, France
| | - Chris Bowler
- Institut de Biologie de l’École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, Paris, France
- Research Federation for the study of Global Ocean Systems Ecology and Evolution, FR2022/Tara Oceans, Paris, France
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16
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Fernández-González C, Tarran GA, Schuback N, Woodward EMS, Arístegui J, Marañón E. Phytoplankton responses to changing temperature and nutrient availability are consistent across the tropical and subtropical Atlantic. Commun Biol 2022; 5:1035. [PMID: 36175608 PMCID: PMC9522883 DOI: 10.1038/s42003-022-03971-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 09/09/2022] [Indexed: 11/24/2022] Open
Abstract
Temperature and nutrient supply interactively control phytoplankton growth and productivity, yet the role of these drivers together still has not been determined experimentally over large spatial scales in the oligotrophic ocean. We conducted four microcosm experiments in the tropical and subtropical Atlantic (29°N-27°S) in which surface plankton assemblages were exposed to all combinations of three temperatures (in situ, 3 °C warming and 3 °C cooling) and two nutrient treatments (unamended and enrichment with nitrogen and phosphorus). We found that chlorophyll a concentration and the biomass of picophytoplankton consistently increase in response to nutrient addition, whereas changes in temperature have a smaller and more variable effect. Nutrient enrichment leads to increased picoeukaryote abundance, depressed Prochlorococcus abundance, and increased contribution of small nanophytoplankton to total biomass. Warming and nutrient addition synergistically stimulate light-harvesting capacity, and accordingly the largest biomass response is observed in the warmed, nutrient-enriched treatment at the warmest and least oligotrophic location (12.7°N). While moderate nutrient increases have a much larger impact than varying temperature upon the growth and community structure of tropical phytoplankton, ocean warming may increase their ability to exploit events of enhanced nutrient availability. Microcosm experiments in the tropical and subtropical Atlantic reveal consistent responses of phytoplankton to changing temperature and nutrient availability, with implications for the impacts of ocean warming in oligotrophic ecosystems.
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Affiliation(s)
- Cristina Fernández-González
- Departamento de Ecoloxía e Bioloxía Animal, Universidade de Vigo, Vigo, Spain.,Centro de Investigacións Mariñas, Universidade de Vigo, Vigo, Spain
| | | | | | | | - Javier Arístegui
- Instituto de Oceanografía y Cambio Global, Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Emilio Marañón
- Departamento de Ecoloxía e Bioloxía Animal, Universidade de Vigo, Vigo, Spain. .,Centro de Investigacións Mariñas, Universidade de Vigo, Vigo, Spain.
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17
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Abstract
The dominant marine filamentous N2 fixer, Trichodesmium, conducts photosynthesis and N2 fixation during the daytime. Because N2 fixation is sensitive to O2, some previous studies suggested that spatial segregation of N2 fixation and photosynthesis is essential in Trichodesmium. However, this hypothesis conflicts with some observations where all the cells contain both photosystems and the N2-fixing enzyme nitrogenase. Here, we construct a systematic model simulating Trichodesmium metabolism, showing that the hypothetical spatial segregation is probably useless in increasing the Trichodesmium growth and N2 fixation, unless substances can efficiently transfer among cells with low loss to the environment. The model suggests that Trichodesmium accumulates fixed carbon in the morning and uses that in respiratory protection to reduce intracellular O2 during the mid-daytime, when photosynthesis is downregulated, allowing the occurrence of N2 fixation. A cell membrane barrier against O2 and alternative non-O2 evolving electron transfer also contribute to maintaining low intracellular O2. Our study provides a mechanism enabling N2 fixation despite the presence of photosynthesis across Trichodesmium. IMPORTANCE The filamentous Trichodesmium is a globally prominent marine nitrogen fixer. A long-standing paradox is that the nitrogen-fixing enzyme nitrogenase is sensitive to oxygen, but Trichodesmium conducts both nitrogen fixation and oxygen-evolving photosynthesis during the daytime. Previous studies using immunoassays reported that nitrogenase was limited in some specialized Trichodesmium cells (termed diazocytes), suggesting the necessity of spatial segregation of nitrogen fixation and photosynthesis. However, attempts using other methods failed to find diazocytes in Trichodesmium, causing controversy on the existence of the spatial segregation. Here, our physiological model shows that Trichodesmium can maintain low intracellular O2 in mid-daytime and achieve feasible nitrogen fixation and growth rates even without the spatial segregation, while the hypothetical spatial segregation might not be useful if substantial loss of substances to the environment occurs when they transfer among the Trichodesmium cells. Our study then suggests a possible mechanism by which Trichodesmium can survive without the spatial segregation.
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18
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Xiao LJ, Xie J, Tan L, Lei LM, Peng L, Wang Z, Naselli-Flores L. Iron enrichment from hypoxic hypolimnion supports the blooming of Raphidiopsis raciborskii in a tropical reservoir. WATER RESEARCH 2022; 219:118562. [PMID: 35580393 DOI: 10.1016/j.watres.2022.118562] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 05/05/2022] [Accepted: 05/06/2022] [Indexed: 06/15/2023]
Abstract
Occurring worldwide, blooms of Raphidiopsis raciborskii threaten the use of water resources especially in tropical and subtropical waterbodies. Its high flexibility in the uses of light and macronutrients (C, N, P) frustrates any bloom prediction and control based on macronutrients regulation. To identify the critical factors promoting periodic blooms of R. raciborskii, the trends of meteorological, hydrodynamic, physical, and chemical variables (including macro- and micronutrients: N, P, Fe) were analyzed in a Chinese tropical large reservoir (Dashahe reservoir) over five years. It was hypothesized that Fe availability, mediated by the mixing pattern of the reservoir, played a crucial role in the periodic blooms of the cyanobacterium. To have a more complete understanding, the effects of Fe on growth of a local R. raciborskii strain were tested in a monoculture experiment. The biomass and relative abundance of R. raciborskii in the reservoir showed a clear seasonal trend, with relative abundance > 50% in summer/autumn (July to October). Three habitat types along a dominance gradient were identified in the reservoir and 17 variables were used to compare them. Statistical analysis and habitat comparison showed that temperature and stratification, dissolved Fe and N concentrations in the epilimnion, and dissolved Fe and oxygen concentrations in the hypolimnion were the critical factors driving the dynamics of R. raciborskii in the study reservoir. The habitat dominated by R. raciborskii was characterized by a relatively low availability of macro resources (Zeu/Zm < 1, SRP < 0.01 mg/L, DIN < 0.3 mg/L) and by a high Fe availability supplemented from hypoxic hypolimnion. The dependence of growth on Fe concentration increase was confirmed in culture where the maximum was reached at 0.689 mg Fe /L. Our results suggest that a high Fe bioavailability, also originating from the hypoxic hypolimnion, influences the dynamics R. raciborskii and favors the blooms of the species. As a consequence, Fe concentrations in the water column as well as oxygen measurements along the water column should be routinely included in the monitoring programs aimed at predicting and controlling R. raciborskii blooms.
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Affiliation(s)
- Li-Juan Xiao
- Department of Ecology, Jinan University, Guangzhou 510632, China
| | - Jing Xie
- Department of Ecology, Jinan University, Guangzhou 510632, China
| | - Lin Tan
- Department of Ecology, Jinan University, Guangzhou 510632, China
| | - La-Mei Lei
- Department of Ecology, Jinan University, Guangzhou 510632, China
| | - Liang Peng
- Department of Ecology, Jinan University, Guangzhou 510632, China.
| | - Zhaohui Wang
- Department of Ecology, Jinan University, Guangzhou 510632, China.
| | - Luigi Naselli-Flores
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Via Archirafi, 28, Palermo 90123, Italy
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19
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Concentration, Spatial-Temporal Distribution, and Bioavailability of Dissolved Reactive Iron in Northern Coastal China Seawater. JOURNAL OF MARINE SCIENCE AND ENGINEERING 2022. [DOI: 10.3390/jmse10070890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The concentrations of total dissolved iron (TdFe) and dissolved reactive iron (DrFe) in the Northern coastal China seawater (Yantai Sishili Bay) in 2018 were determined using cathodic stripping voltammetry (CSV). It was found that while the concentrations of TdFe ranged from 27.8 to 82.0 nM, DrFe concentrations changed in a much narrower range from 6.8 to 13.3 nM. The annual mean concentrations of DrFe also ranged from 7.1 to 12.6 nM at the 12 sites monitored over the 4 years of the study (2017–2020). Considering the obvious changes in temperature (T), chlorophyll a (Chl a) concentrations (Chl a contents were higher in May, July and September than in March and November), and nutrients over a year in this zone, the consumption of DrFe was expected; the supplement of DrFe observed may have resulted from the transformation of strong organically complexed iron by photoreduction and cell surface reduction. Additionally, a pre-liminary conclusion was drawn based on the theoretical calculation of Fe* that the concentration of DrFe was sufficient to meet the phytoplankton demand.
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20
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Transcriptomic Analysis of the Molecular Response Mechanism of Microcystis aeruginosa to Iron Limitation Stress. WATER 2022. [DOI: 10.3390/w14111679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Iron is an essential micronutrient for cyanobacteria. It is involved in physiological activities such as photosynthesis, respiration, and the synthesis of pigments. The impact of iron limitation on planktonic algae growth occurs in surface oceans globally, as well as in freshwater ecosystems. However, the molecular and physiological effects and response mechanism of cyanobacteria under iron-limited conditions have not been reported in detail. In this study, the effects of iron limitation on the cell density, chlorophyll content, and photosynthetic activity of Microcystis aeruginosa were determined, and transcriptome sequencing was undertaken. In a severely iron-deficient environment, the cell density and chlorophyll-a content of M. aeruginosa were significantly lower than in the iron-rich group (a 55.42% and 83.51% reduction, respectively). Similarly, the photosynthetic efficiency of M. aeruginosa was also inhibited by iron deficiency, and the maximum photochemical efficiency (Fv/Fm) of the severe iron deficiency group was only 66.72% of the control group. The transcriptome results showed that to cope with the iron-deficient environment, most genes involved in iron absorption and transport in M. aeruginosa were up-regulated. In particular, the fur and perR genes that regulate the iron uptake regulatory protein (Fur) were both up-regulated. Due to the high demand for iron in the photosynthetic electron transport chain of M. aeruginosa, most photosynthesis-related genes were down-regulated, for example, petJ, which regulates iron-containing cytochrome c6. In contrast, most of the genes related to glycolysis and respiration were up-regulated. These changes in gene expression may be a survival strategy for M. aeruginosa to cope with a long-term iron-deficient environment. This study provides insights into the molecular response mechanism of M. aeruginosa under iron limitation stress.
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21
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Wang B, Chen M, Zheng M, Qiu Y. The biological uptake of dissolved iron in the changing Daya Bay, South China Sea: Effect of pH and DO. MARINE POLLUTION BULLETIN 2022; 178:113635. [PMID: 35421641 DOI: 10.1016/j.marpolbul.2022.113635] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 03/29/2022] [Accepted: 03/30/2022] [Indexed: 06/14/2023]
Abstract
The oceanic acidification and coastal hypoxia have potential to enhance biological uptake of dissolved iron (Fe) by phytoplankton. In this study, the Fe uptake rate (FeUR) in Daya Bay was significantly negatively correlated with pH and dissolved oxygen (DO) (r = -0.81 and -0.73, respectively, p < 0.001). In addition, binary regression (FeUR = -1.45 × pH - 0.10 × DO + 13.64) also indicated that both pH and DO played key roles in FeUR variations. As pH and DO decreased, Fe uptake by phytoplankton was promoted, and the contribution of nano-phytoplankton to Fe uptake increased significantly, while that of pico-FeUR decreased. These will result in the phytoplankton community to be miniaturized and Fe requirement of phytoplankton goes higher, thereby leading changes of phytoplankton composition and coastal ecosystem. This study helps to understand how Fe could affect the coastal ecosystem under the increasing anthropogenic influences.
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Affiliation(s)
- Bo Wang
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590, China
| | - Min Chen
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China.
| | - Minfang Zheng
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Yusheng Qiu
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
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22
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Zhu Y, Feng Y, Browning TJ, Wen Z, Hughes DJ, Hao Q, Zhang R, Meng Q, Wells ML, Jiang Z, Dissanayake PAKN, Priyadarshani WNC, Shou L, Zeng J, Chai F. Exploring Variability of Trichodesmium Photophysiology Using Multi-Excitation Wavelength Fast Repetition Rate Fluorometry. Front Microbiol 2022; 13:813573. [PMID: 35464918 PMCID: PMC9026164 DOI: 10.3389/fmicb.2022.813573] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 02/11/2022] [Indexed: 11/20/2022] Open
Abstract
Fast repetition rate fluorometry (FRRf) allows for rapid non-destructive assessment of phytoplankton photophysiology in situ yet has rarely been applied to Trichodesmium. This gap reflects long-standing concerns that Trichodesmium (and other cyanobacteria) contain pigments that are less effective at absorbing blue light which is often used as the sole excitation source in FRR fluorometers-potentially leading to underestimation of key fluorescence parameters. In this study, we use a multi-excitation FRR fluorometer (equipped with blue, green, and orange LEDs) to investigate photophysiological variability in Trichodesmium assemblages from two sites. Using a multi-LED measurement protocol (447+519+634 nm combined), we assessed maximum photochemical efficiency (F v /F m ), functional absorption cross section of PSII (σ PSII ), and electron transport rates (ETRs) for Trichodesmium assemblages in both the Northwest Pacific (NWP) and North Indian Ocean in the vicinity of Sri Lanka (NIO-SL). Evaluating fluorometer performance, we showed that use of a multi-LED measuring protocol yields a significant increase of F v /F m for Trichodesmium compared to blue-only excitation. We found distinct photophysiological differences for Trichodesmium at both locations with higher average F v /F m as well as lower σ PSII and non-photochemical quenching (NPQ NSV ) observed in the NWP compared to the NIO-SL (Kruskal-Wallis t-test df = 1, p < 0.05). Fluorescence light response curves (FLCs) further revealed differences in ETR response with a lower initial slope (α ETR ) and higher maximum electron turnover rate ( E T R P S I I m a x ) observed for Trichodesmium in the NWP compared to the NIO-SL, translating to a higher averaged light saturation E K (= E T R P S I I m a x /α ETR ) for cells at this location. Spatial variations in physiological parameters were both observed between and within regions, likely linked to nutrient supply and physiological stress. Finally, we applied an algorithm to estimate primary productivity of Trichodesmium using FRRf-derived fluorescence parameters, yielding an estimated carbon-fixation rate ranging from 7.8 to 21.1 mgC mg Chl-a-1 h-1 across this dataset. Overall, our findings demonstrate that capacity of multi-excitation FRRf to advance the application of Chl-a fluorescence techniques in phytoplankton assemblages dominated by cyanobacteria and reveals novel insight into environmental regulation of photoacclimation in natural Trichodesmium populations.
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Affiliation(s)
- Yuanli Zhu
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Yuanyuan Feng
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
| | - Thomas J. Browning
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Zuozhu Wen
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China
| | - David J. Hughes
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia
| | - Qiang Hao
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Ruifeng Zhang
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
| | - Qicheng Meng
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Mark L. Wells
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
- Darling Marine Center, University of Maine, Walpole, ME, United States
| | - Zhibing Jiang
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - P. A. K. N. Dissanayake
- Department of Oceanography and Marine Geology, Faculty of Fisheries and Marine Sciences and Technology, University of Ruhuna, Matara, Sri Lanka
| | - W. N. C. Priyadarshani
- National Institute of Oceanography and Marine Sciences, National Aquatic Resources Research and Development Agency, Colombo, Sri Lanka
| | - Lu Shou
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Jiangning Zeng
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Fei Chai
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
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Cerdan-Garcia E, Baylay A, Polyviou D, Woodward EMS, Wrightson L, Mahaffey C, Lohan MC, Moore CM, Bibby TS, Robidart JC. Transcriptional responses of Trichodesmium to natural inverse gradients of Fe and P availability. THE ISME JOURNAL 2022; 16:1055-1064. [PMID: 34819612 PMCID: PMC8941076 DOI: 10.1038/s41396-021-01151-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 10/28/2021] [Accepted: 11/01/2021] [Indexed: 12/28/2022]
Abstract
The filamentous diazotrophic cyanobacterium Trichodesmium is responsible for a significant fraction of marine di-nitrogen (N2) fixation. Growth and distribution of Trichodesmium and other diazotrophs in the vast oligotrophic subtropical gyres is influenced by iron (Fe) and phosphorus (P) availability, while reciprocally influencing the biogeochemistry of these nutrients. Here we use observations across natural inverse gradients in Fe and P in the North Atlantic subtropical gyre (NASG) to demonstrate how Trichodesmium acclimates in situ to resource availability. Transcriptomic analysis identified progressive upregulation of known iron-stress biomarker genes with decreasing Fe availability, and progressive upregulation of genes involved in the acquisition of diverse P sources with decreasing P availability, while genes involved in N2 fixation were upregulated at the intersection under moderate Fe and P availability. Enhanced N2 fixation within the Fe and P co-stressed transition region was also associated with a distinct, consistent metabolic profile, including the expression of alternative photosynthetic pathways that potentially facilitate ATP generation required for N2 fixation with reduced net oxygen production. The observed response of Trichodesmium to availability of both Fe and P supports suggestions that these biogeochemically significant organisms employ unique molecular, and thus physiological responses as adaptations to specifically exploit the Fe and P co-limited niche they construct.
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Affiliation(s)
- E Cerdan-Garcia
- Ocean and Earth Science, University of Southampton, Southampton, SO14 3ZH, UK.
| | - A Baylay
- Ocean and Earth Science, University of Southampton, Southampton, SO14 3ZH, UK
| | - D Polyviou
- National Oceanography Centre, Southampton, SO14 3ZH, UK
| | | | - L Wrightson
- Earth, Ocean and Ecological Sciences, University of Liverpool, Liverpool, L69 3BX, UK
| | - C Mahaffey
- Earth, Ocean and Ecological Sciences, University of Liverpool, Liverpool, L69 3BX, UK
| | - M C Lohan
- Ocean and Earth Science, University of Southampton, Southampton, SO14 3ZH, UK
| | - C M Moore
- Ocean and Earth Science, University of Southampton, Southampton, SO14 3ZH, UK
| | - T S Bibby
- Ocean and Earth Science, University of Southampton, Southampton, SO14 3ZH, UK
| | - J C Robidart
- National Oceanography Centre, Southampton, SO14 3ZH, UK.
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Iron and manganese co-limit the growth of two phytoplankton groups dominant at two locations of the Drake Passage. Commun Biol 2022; 5:207. [PMID: 35246600 PMCID: PMC8897415 DOI: 10.1038/s42003-022-03148-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 02/07/2022] [Indexed: 11/14/2022] Open
Abstract
While it has been recently demonstrated that both iron (Fe) and manganese (Mn) control Southern Ocean (SO) plankton biomass, how in particular Mn governs phytoplankton species composition remains yet unclear. This study, for the first time, highlights the importance of Mn next to Fe for growth of two key SO phytoplankton groups at two locations in the Drake Passage (West and East). Even though the bulk parameter chlorophyll a indicated Fe availability as main driver of both phytoplankton assemblages, the flow cytometric and microscopic analysis revealed FeMn co-limitation of a key phytoplankton group at each location: at West the dominant diatom Fragilariopsis and one subgroup of picoeukaryotes, which numerically dominated the East community. Hence, the limitation by both Fe and Mn and their divergent requirements among phytoplankton species and groups can be a key factor for shaping SO phytoplankton community structure. Iron and manganese play an important role in phytoplankton biomass control, but the exact effect of these elements on species composition has remained unknown. Conducting phytoplankton incubation experiments at two Drake Passage sites, we demonstrate how iron and manganese regulate phytoplankton community structure.
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25
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Gorbunov MY, Falkowski PG. Using Chlorophyll Fluorescence to Determine the Fate of Photons Absorbed by Phytoplankton in the World's Oceans. ANNUAL REVIEW OF MARINE SCIENCE 2022; 14:213-238. [PMID: 34460315 DOI: 10.1146/annurev-marine-032621-122346] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Approximately 45% of the photosynthetically fixed carbon on Earth occurs in the oceans in phytoplankton, which account for less than 1% of the world's photosynthetic biomass. This amazing empirical observation implies a very high photosynthetic energy conversion efficiency, but how efficiently is the solar energy actually used? The photon energy budget of photosynthesis can be divided into three terms: the quantum yields of photochemistry, fluorescence, and heat. Measuring two of these three processes closes the energy budget. The development of ultrasensitive, seagoing chlorophyll variable fluorescence and picosecond fluorescence lifetime instruments has allowed independent closure on the first two terms. With this closure, we can understand how phytoplankton respond to nutrient supplies on timescales of hours to months and, over longer timescales, to changes in climate.
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Affiliation(s)
- Maxim Y Gorbunov
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, USA; ,
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, USA; ,
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26
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Camoying MG, Thoms S, Geuer JK, Koch BP, Bischof K, Trimborn S. In contrast to diatoms, cryptophytes are susceptible to iron limitation, but not to ocean acidification. PHYSIOLOGIA PLANTARUM 2022; 174:e13614. [PMID: 35199361 DOI: 10.1111/ppl.13614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 12/09/2021] [Accepted: 12/17/2021] [Indexed: 06/14/2023]
Abstract
Previous field studies in the Southern Ocean (SO) indicated an increased occurrence and dominance of cryptophytes over diatoms due to climate change. To gain a better mechanistic understanding of how the two ecologically important SO phytoplankton groups cope with ocean acidification (OA) and iron (Fe) availability, we chose two common representatives of Antarctic waters, the cryptophyte Geminigera cryophila and the diatom Pseudo-nitzschia subcurvata. Both species were grown at 2°C under different pCO2 (400 vs. 900 μatm) and Fe (0.6 vs. 1.2 nM) conditions. For P. subcurvata, an additional high pCO2 level was applied (1400 μatm). At ambient pCO2 under low Fe supply, growth of G. cryophila almost stopped while it remained unaffected in P. subcurvata. Under high Fe conditions, OA was not beneficial for P. subcurvata, but stimulated growth and carbon production of G. cryophila. Under low Fe supply, P. subcurvata coped much better with OA than the cryptophyte, but invested more energy into photoacclimation. Our study reveals that Fe limitation was detrimental for the growth of G. cryophila and suppressed the positive OA effect. The diatom was efficient in coping with low Fe, but was stressed by OA while both factors together strongly impacted its growth. The distinct physiological response of both species to OA and Fe limitation explains their occurrence in the field. Based on our results, Fe availability is an important modulator of OA effects on SO phytoplankton, with different implications on the occurrence of cryptophytes and diatoms in the future.
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Affiliation(s)
- Marianne G Camoying
- Ecological Chemistry, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Silke Thoms
- Ecological Chemistry, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Jana K Geuer
- Ecological Chemistry, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Boris P Koch
- Ecological Chemistry, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
- Department of Technology, University of Applied Sciences Bremerhaven, Bremerhaven, Germany
| | - Kai Bischof
- Marine Botany & MARUM, University of Bremen, Bremen, Germany
| | - Scarlett Trimborn
- Ecological Chemistry, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
- Marine Botany & MARUM, University of Bremen, Bremen, Germany
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27
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Buck JM, Wünsch M, Schober AF, Kroth PG, Lepetit B. Impact of Lhcx2 on Acclimation to Low Iron Conditions in the Diatom Phaeodactylum tricornutum. FRONTIERS IN PLANT SCIENCE 2022; 13:841058. [PMID: 35371185 PMCID: PMC8967352 DOI: 10.3389/fpls.2022.841058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 01/24/2022] [Indexed: 05/09/2023]
Abstract
Iron is a cofactor of photosystems and electron carriers in the photosynthetic electron transport chain. Low concentrations of dissolved iron are, therefore, the predominant factor that limits the growth of phototrophs in large parts of the open sea like the Southern Ocean and the North Pacific, resulting in "high nutrient-low chlorophyll" (HNLC) areas. Diatoms are among the most abundant microalgae in HNLC zones. Besides efficient iron uptake mechanisms, efficient photoprotection might be one of the key traits enabling them to outcompete other algae in HNLC regions. In diatoms, Lhcx proteins play a crucial role in one of the main photoprotective mechanisms, the energy-dependent fluorescence quenching (qE). The expression of Lhcx proteins is strongly influenced by various environmental triggers. We show that Lhcx2 responds specifically and in a very sensitive manner to iron limitation in the diatom Phaeodactylum tricornutum on the same timescale as the known iron-regulated genes ISIP1 and CCHH11. By comparing Lhcx2 knockout lines with wild type cells, we reveal that a strongly increased qE under iron limitation is based on the upregulation of Lhcx2. Other observed iron acclimation phenotypes in P. tricornutum include a massively reduced chlorophyll a content/cell, a changed ratio of light harvesting and photoprotective pigments per chlorophyll a, a decreased amount of photosystem II and photosystem I cores, an increased functional photosystem II absorption cross section, and decoupled antenna complexes. H2O2 formation at photosystem I induced by high light is lowered in iron-limited cells, while the amount of total reactive oxygen species is rather increased. Our data indicate a possible reduction in singlet oxygen by Lhcx2-based qE, while the other iron acclimation phenotype parameters monitored are not affected by the amount of Lhcx2 and qE.
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28
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Jia A, Zheng Y, Chen H, Wang Q. Regulation and Functional Complexity of the Chlorophyll-Binding Protein IsiA. Front Microbiol 2021; 12:774107. [PMID: 34867913 PMCID: PMC8635728 DOI: 10.3389/fmicb.2021.774107] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 10/25/2021] [Indexed: 11/17/2022] Open
Abstract
As the oldest known lineage of oxygen-releasing photosynthetic organisms, cyanobacteria play the key roles in helping shaping the ecology of Earth. Iron is an ideal transition metal for redox reactions in biological systems. Cyanobacteria frequently encounter iron deficiency due to the environmental oxidation of ferrous ions to ferric ions, which are highly insoluble at physiological pH. A series of responses, including architectural changes to the photosynthetic membranes, allow cyanobacteria to withstand this condition and maintain photosynthesis. Iron-stress-induced protein A (IsiA) is homologous to the cyanobacterial chlorophyll (Chl)-binding protein, photosystem II core antenna protein CP43. IsiA is the major Chl-containing protein in iron-starved cyanobacteria, binding up to 50% of the Chl in these cells, and this Chl can be released from IsiA for the reconstruction of photosystems during the recovery from iron limitation. The pigment–protein complex (CPVI-4) encoded by isiA was identified and found to be expressed under iron-deficient conditions nearly 30years ago. However, its precise function is unknown, partially due to its complex regulation; isiA expression is induced by various types of stresses and abnormal physiological states besides iron deficiency. Furthermore, IsiA forms a range of complexes that perform different functions. In this article, we describe progress in understanding the regulation and functions of IsiA based on laboratory research using model cyanobacteria.
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Affiliation(s)
- Anqi Jia
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Yanli Zheng
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Hui Chen
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Qiang Wang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
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29
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Buck JM, Kroth PG, Lepetit B. Identification of sequence motifs in Lhcx proteins that confer qE-based photoprotection in the diatom Phaeodactylum tricornutum. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 108:1721-1734. [PMID: 34651379 DOI: 10.1111/tpj.15539] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 08/11/2021] [Indexed: 05/08/2023]
Abstract
Photosynthetic organisms in nature often experience light fluctuations. While low light conditions limit the energy uptake by algae, light absorption exceeding the maximal rate of photosynthesis may go along with enhanced formation of potentially toxic reactive oxygen species. To preempt high light-induced photodamage, photosynthetic organisms evolved numerous photoprotective mechanisms. Among these, energy-dependent fluorescence quenching (qE) provides a rapid mechanism to dissipate thermally the excessively absorbed energy. Diatoms thrive in all aquatic environments and thus belong to the most important primary producers on earth. qE in diatoms is provided by a concerted action of Lhcx proteins and the xanthophyll cycle pigment diatoxanthin. While the exact Lhcx activation mechanism of diatom qE is unknown, two lumen-exposed acidic amino acids within Lhcx proteins were proposed to function as regulatory switches upon light-induced lumenal acidification. By introducing a modified Lhcx1 lacking these amino acids into a Phaeodactylum tricornutum Lhcx1-null qE knockout line, we demonstrate that qE is unaffected by these two amino acids. Based on sequence comparisons with Lhcx4, being incapable of providing qE, we perform domain swap experiments of Lhcx4 with Lhcx1 and identify two peptide motifs involved in conferring qE. Within one of these motifs, we identify a tryptophan residue with a major influence on qE establishment. This tryptophan residue is located in close proximity to the diadinoxanthin/diatoxanthin-binding site based on the recently revealed diatom Lhc crystal structure. Our findings provide a structural explanation for the intimate link of Lhcx and diatoxanthin in providing qE in diatoms.
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Affiliation(s)
- Jochen M Buck
- Plant Ecophysiology, Department of Biology, University of Konstanz, Konstanz, 78457, Germany
| | - Peter G Kroth
- Plant Ecophysiology, Department of Biology, University of Konstanz, Konstanz, 78457, Germany
| | - Bernard Lepetit
- Plant Ecophysiology, Department of Biology, University of Konstanz, Konstanz, 78457, Germany
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30
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Brown M, Milligan A, Behrenfeld M. Photoacclimation State of Thalassiosira weissflogii is not Affected by Changes in Optical Depth Under A Fluctuating Light Regime Simulating Deep Mixing 1. JOURNAL OF PHYCOLOGY 2021; 57:1212-1222. [PMID: 33590492 DOI: 10.1111/jpy.13149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 01/26/2021] [Accepted: 01/28/2021] [Indexed: 05/25/2023]
Abstract
Satellite-based remote sensing allows for global estimates of phytoplankton primary productivity by converting measurements of ocean color or photon absorption into units of carbon fixation. Models which perform this conversion often require an estimate of phytoplankton photoacclimation state such as the carbon to chlorophyll a ratio (C:Chl). Recently, our group developed a new photoacclimation model that can be applied to models of primary production. The model assumes that the phytoplankton photoacclimation state is not affected by periods of darkness during deep mixing beneath the photic zone, due to reduction in the plastoquinone pool in darkness and the subsequent deactivation of the signal for chlorophyll synthesis. In this study, we tested these assumptions by culturing the marine diatom Thalassiosira weissflogii under fluctuating light conditions simulating three different optical depths with progressively increasing deep mixing periods. The photoacclimation state, measured by the ratio of C:Chl, in T. weissflogii was not affected by changes in the length of simulated deep mixing periods. In addition, analysis of photosynthesis vs. irradiance (PE) curves showed that increases in optical depth caused decreases in both the maximum Chl-normalized rate of photosynthesis (Pbmax ) and in the slope of light-limited photosynthesis (αb ), but had no effect on the half-saturation irradiance (Ek , another metric of photoacclimation). However, measurements of chlorophyll fluorescence during simulated deep mixing did not support the hypothesis that the PQ pool was reduced during dark periods. Thus, our findings support the use of the photoacclimation model for estimating primary production while suggesting the need for further research into the mechanisms controlling photoacclimation in the upper mixed layer environment of the ocean.
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Affiliation(s)
- Matthew Brown
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, 97331, USA
| | - Allen Milligan
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, 97331, USA
| | - Michael Behrenfeld
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, 97331, USA
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31
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Kotabova E, Malych R, Pierella Karlusich JJ, Kazamia E, Eichner M, Mach J, Lesuisse E, Bowler C, Prášil O, Sutak R. Complex Response of the Chlorarachniophyte Bigelowiella natans to Iron Availability. mSystems 2021; 6:e00738-20. [PMID: 33563784 PMCID: PMC7883536 DOI: 10.1128/msystems.00738-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 01/10/2021] [Indexed: 11/20/2022] Open
Abstract
The productivity of the ocean is largely dependent on iron availability, and marine phytoplankton have evolved sophisticated mechanisms to cope with chronically low iron levels in vast regions of the open ocean. By analyzing the metabarcoding data generated from the Tara Oceans expedition, we determined how the global distribution of the model marine chlorarachniophyte Bigelowiella natans varies across regions with different iron concentrations. We performed a comprehensive proteomics analysis of the molecular mechanisms underpinning the adaptation of B. natans to iron scarcity and report on the temporal response of cells to iron enrichment. Our results highlight the role of phytotransferrin in iron homeostasis and indicate the involvement of CREG1 protein in the response to iron availability. Analysis of the Tara Oceans metagenomes and metatranscriptomes also points to a similar role for CREG1, which is found to be widely distributed among marine plankton but to show a strong bias in gene and transcript abundance toward iron-deficient regions. Our analyses allowed us to define a new subfamily of the CobW domain-containing COG0523 putative metal chaperones which are involved in iron metabolism and are restricted to only a few phytoplankton lineages in addition to B. natans At the physiological level, we elucidated the mechanisms allowing a fast recovery of PSII photochemistry after resupply of iron. Collectively, our study demonstrates that B. natans is well adapted to dynamically respond to a changing iron environment and suggests that CREG1 and COG0523 are important components of iron homeostasis in B. natans and other phytoplankton.IMPORTANCE Despite low iron availability in the ocean, marine phytoplankton require considerable amounts of iron for their growth and proliferation. While there is a constantly growing knowledge of iron uptake and its role in the cellular processes of the most abundant marine photosynthetic groups, there are still largely overlooked branches of the eukaryotic tree of life, such as the chlorarachniophytes. In the present work, we focused on the model chlorarachniophyte Bigelowiella natans, integrating physiological and proteomic analyses in culture conditions with the mining of omics data generated by the Tara Oceans expedition. We provide unique insight into the complex responses of B. natans to iron availability, including novel links to iron metabolism conserved in other phytoplankton lineages.
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Affiliation(s)
- Eva Kotabova
- Institute of Microbiology, Academy of Sciences, Centrum Algatech, Trebon, Czech Republic
| | - Ronald Malych
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Juan José Pierella Karlusich
- Institut de Biologie de l'ENS, Département de Biologie, École Normale Supérieure, CNRS, INSERM, Université PSL, Paris, France
- CNRS Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/Tara Oceans GOSEE, Paris, France
| | - Elena Kazamia
- Institut de Biologie de l'ENS, Département de Biologie, École Normale Supérieure, CNRS, INSERM, Université PSL, Paris, France
| | - Meri Eichner
- Institute of Microbiology, Academy of Sciences, Centrum Algatech, Trebon, Czech Republic
| | - Jan Mach
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Emmanuel Lesuisse
- Jacques Monod Institute, UMR7592 CNRS, Paris Diderot University, Paris, France
| | - Chris Bowler
- Institut de Biologie de l'ENS, Département de Biologie, École Normale Supérieure, CNRS, INSERM, Université PSL, Paris, France
- CNRS Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/Tara Oceans GOSEE, Paris, France
| | - Ondřej Prášil
- Institute of Microbiology, Academy of Sciences, Centrum Algatech, Trebon, Czech Republic
| | - Robert Sutak
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
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32
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Reich HG, Tu WC, Rodriguez IB, Chou Y, Keister EF, Kemp DW, LaJeunesse TC, Ho TY. Iron Availability Modulates the Response of Endosymbiotic Dinoflagellates to Heat Stress. JOURNAL OF PHYCOLOGY 2021; 57:3-13. [PMID: 32996595 DOI: 10.1111/jpy.13078] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 09/03/2020] [Accepted: 09/11/2020] [Indexed: 06/11/2023]
Abstract
Warming and nutrient limitation are stressors known to weaken the health of microalgae. In situations of stress, access to energy reserves can minimize physiological damage. Because of its widespread requirements in biochemical processes, iron is an important trace metal, especially for photosynthetic organisms. Lowered iron availability in oceans experiencing rising temperatures may contribute to the thermal sensitivity of reef-building corals, which rely on mutualisms with dinoflagellates to survive. To test the influence of iron concentration on thermal sensitivity, the physiological responses of cultured symbiotic dinoflagellates (genus Breviolum; family Symbiodiniaceae) were evaluated when exposed to increasing temperatures (26 to 30°C) and iron concentrations ranging from replete (500 pM Fe') to limiting (50 pM Fe') under a diurnal light cycle with saturating radiance. Declines in photosynthetic efficiency at elevated temperatures indicated sensitivity to heat stress. Furthermore, five times the amount of iron was needed to reach exponential growth during heat stress (50 pM Fe' at 26-28°C vs. 250 pM Fe' at 30°C). In treatments where exponential growth was reached, Breviolum psygmophilum grew faster than B.minutum, possibly due to greater cellular contents of iron and other trace metals. The metal composition of B.psygmophilum shifted only at the highest temperature (30°C), whereas changes in B.minutum were observed at lower temperatures (28°C). The influence of iron availability in modulating each alga's response to thermal stress suggests the importance of trace metals to the health of coral-algal mutualisms. Ultimately, a greater ability to acquire scarce metals may improve the tolerance of corals to physiological stressors and contribute to the differences in performance associated with hosting one symbiont species over another.
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Affiliation(s)
- Hannah G Reich
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Wan-Chen Tu
- Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
| | - Irene B Rodriguez
- Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
| | - Yalan Chou
- Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
| | - Elise F Keister
- Department of Biology, The University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA
| | - Dustin W Kemp
- Department of Biology, The University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA
| | - Todd C LaJeunesse
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Tung-Yuan Ho
- Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
- Institute of Oceanography, National Taiwan University, Taipei, Taiwan
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Bozzato D, Jakob T, Wilhelm C, Trimborn S. Effects of iron limitation on carbon balance and photophysiology of the Antarctic diatom Chaetoceros cf. simplex. Polar Biol 2021. [DOI: 10.1007/s00300-020-02785-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
AbstractIn the Southern Ocean (SO), iron (Fe) limitation strongly inhibits phytoplankton growth and generally decreases their primary productivity. Diatoms are a key component in the carbon (C) cycle, by taking up large amounts of anthropogenic CO2 through the biological carbon pump. In this study, we investigated the effects of Fe availability (no Fe and 4 nM FeCl3 addition) on the physiology of Chaetoceros cf. simplex, an ecologically relevant SO diatom. Our results are the first combining oxygen evolution and uptake rates with particulate organic carbon (POC) build up, pigments, photophysiological parameters and intracellular trace metal (TM) quotas in an Fe-deficient Antarctic diatom. Decreases in both oxygen evolution (through photosynthesis, P) and uptake (respiration, R) coincided with a lowered growth rate of Fe-deficient cells. In addition, cells displayed reduced electron transport rates (ETR) and chlorophyll a (Chla) content, resulting in reduced cellular POC formation. Interestingly, no differences were observed in non-photochemical quenching (NPQ) or in the ratio of gross photosynthesis to respiration (GP:R). Furthermore, TM quotas were measured, which represent an important and rarely quantified parameter in previous studies. Cellular quotas of manganese, zinc, cobalt and copper remained unchanged while Fe quotas of Fe-deficient cells were reduced by 60% compared with High Fe cells. Based on our data, Fe-deficient Chaetoceros cf. simplex cells were able to efficiently acclimate to low Fe conditions, reducing their intracellular Fe concentrations, the number of functional reaction centers of photosystem II (RCII) and photosynthetic rates, thus avoiding light absorption rather than dissipating the energy through NPQ. Our results demonstrate how Chaetoceros cf. simplex can adapt their physiology to lowered assimilatory metabolism by decreasing respiratory losses.
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34
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Divergence of photosynthetic strategies amongst marine diatoms. PLoS One 2020; 15:e0244252. [PMID: 33370327 PMCID: PMC7769462 DOI: 10.1371/journal.pone.0244252] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 12/07/2020] [Indexed: 11/19/2022] Open
Abstract
Marine phytoplankton, and in particular diatoms, are responsible for almost half of all primary production on Earth. Diatom species thrive from polar to tropical waters and across light environments that are highly complex to relatively benign, and so have evolved highly divergent strategies for regulating light capture and utilization. It is increasingly well established that diatoms have achieved such successful ecosystem dominance by regulating excitation energy available for generating photosynthetic energy via highly flexible light harvesting strategies. However, how different light harvesting strategies and downstream pathways for oxygen production and consumption interact to balance excitation pressure remains unknown. We therefore examined the responses of three diatom taxa adapted to inherently different light climates (estuarine Thalassioisira weissflogii, coastal Thalassiosira pseudonana and oceanic Thalassiosira oceanica) during transient shifts from a moderate to high growth irradiance (85 to 1200 μmol photons m-2 s-1). Transient high light exposure caused T. weissflogii to rapidly downregulate PSII with substantial nonphotochemical quenching, protecting PSII from inactivation or damage, and obviating the need for induction of O2 consuming (light-dependent respiration, LDR) pathways. In contrast, T. oceanica retained high excitation pressure on PSII, but with little change in RCII photochemical turnover, thereby requiring moderate repair activity and greater reliance on LDR. T. pseudonana exhibited an intermediate response compared to the other two diatom species, exhibiting some downregulation and inactivation of PSII, but high repair of PSII and induction of reversible PSII nonphotochemical quenching, with some LDR. Together, these data demonstrate a range of strategies for balancing light harvesting and utilization across diatom species, which reflect their adaptation to sustain photosynthesis under environments with inherently different light regimes.
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Sherman J, Gorbunov MY, Schofield O, Falkowski PG. Photosynthetic energy conversion efficiency in the West Antarctic Peninsula. LIMNOLOGY AND OCEANOGRAPHY 2020; 65:2912-2925. [PMID: 33380749 PMCID: PMC7754432 DOI: 10.1002/lno.11562] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 04/18/2020] [Accepted: 06/23/2020] [Indexed: 06/12/2023]
Abstract
The West Antarctic Peninsula (WAP) is a highly productive polar ecosystem where phytoplankton dynamics are regulated by intense bottom-up control from light and iron availability. Rapid climate change along the WAP is driving shifts in the mixed layer depth and iron availability. Elucidating the relative role of each of these controls and their interactions is crucial for understanding of how primary productivity will change in coming decades. Using a combination of ultra-high-resolution variable chlorophyll fluorescence together with fluorescence lifetime analyses on the 2017 Palmer Long Term Ecological Research cruise, we mapped the temporal and spatial variability in phytoplankton photophysiology across the WAP. Highest photosynthetic energy conversion efficiencies and lowest fluorescence quantum yields were observed in iron replete coastal regions. Photosynthetic energy conversion efficiencies decreased by ~ 60% with a proportional increase in quantum yields of thermal dissipation and fluorescence on the outer continental shelf and slope. The combined analysis of variable fluorescence and lifetimes revealed that, in addition to the decrease in the fraction of inactive reaction centers, up to 20% of light harvesting chlorophyll-protein antenna complexes were energetically uncoupled from photosystem II reaction centers in iron-limited phytoplankton. These biophysical signatures strongly suggest severe iron limitation of photosynthesis in the surface waters along the continental slope of the WAP.
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Affiliation(s)
- Jonathan Sherman
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, RutgersThe State University of New JerseyNew BrunswickNew JerseyUSA
| | - Maxim Y. Gorbunov
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, RutgersThe State University of New JerseyNew BrunswickNew JerseyUSA
| | - Oscar Schofield
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, RutgersThe State University of New JerseyNew BrunswickNew JerseyUSA
- Center for Ocean Observing Leadership, Department of Marine and Coastal SciencesRutgers, The State University of New JerseyNew BrunswickNew JerseyUSA
| | - Paul G. Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, RutgersThe State University of New JerseyNew BrunswickNew JerseyUSA
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Li ZK, Dai GZ, Zhang Y, Xu K, Bretherton L, Finkel ZV, Irwin AJ, Juneau P, Qiu BS. Photosynthetic adaptation to light availability shapes the ecological success of bloom-forming cyanobacterium Pseudanabaena to iron limitation. JOURNAL OF PHYCOLOGY 2020; 56:1457-1467. [PMID: 32557638 DOI: 10.1111/jpy.13040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 05/06/2020] [Indexed: 06/11/2023]
Abstract
The poorly understood filamentous cyanobacterium Pseudanabaena is commonly epiphytic on Microcystis colonies and their abundances are often highly correlated during blooms. The response and adaptation of Microcystis to iron limitation have been extensively studied, but the strategies Pseudanabaena uses to respond to iron limitation are largely unknown. Here, physiological responses to iron limitation were compared between one Pseudanabaena and two Microcystis strains grown under different light intensities. The results showed that low-intensity light exacerbated, but high-intensity light alleviated, the negative effect of iron limitation on Pseudanabaena growth relative to two Microcystis strains. It was found that robust light-harvesting and photosynthetic efficiency allowed adaptation of Pseudanabaena to low light availability relative to two Microcystis strains only during iron sufficiency. The results also indicated that a larger investment in the photosynthetic antenna probably contributed to light/iron co-limitation of Pseudanabaena relative to two Microcystis strains under both light and iron limitation. Furthermore, the lower antenna pigments/chlorophyll a ratio and photosynthetic efficiency, and higher nonphotochemical quenching and saturation irradiance provided Pseudanabaena photoadaptation and photoprotection advantages over the two Microcystis strains under the high-light condition. The lower investment in antenna pigments of Pseudanabaena than the two Microcystis strains under high-light intensity is likely an efficient strategy for both saving iron quotas and decreasing photosensitivity. Therefore, when compared with Microcystis, the high plasticity of antenna pigments, along with the excellent photoadaptation and photoprotection ability of Pseudanabaena, probably ensures its ecological success under iron limitation when light is sufficient.
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Affiliation(s)
- Zheng-Ke Li
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, People's Republic of China
| | - Guo-Zheng Dai
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, People's Republic of China
| | - Yong Zhang
- College of Environmental Science and Engineering, Fujian Normal University, Fuzhou, Fujian, 350007, People's Republic of China
| | - Kui Xu
- School of Environmental Science and Engineering, Environmental Microbiomics Research Center, Sun Yat-Sen University, Guangzhou, Guangdong, 510006, People's Republic of China
| | - Laura Bretherton
- Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Zoe V Finkel
- Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Andrew J Irwin
- Department of Mathematics and Statistics, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Philippe Juneau
- Ecotoxicology of Aquatic Microorganisms Laboratory - Department of Biological Sciences, GRIL - EcotoQ - TOXEN, Université du Québec à Montréal, Succ. Centre-Ville, Montréal, Québec, H3C 3P8, Canada
| | - Bao-Sheng Qiu
- School of Life Sciences, and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, People's Republic of China
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Seasonal modulation of phytoplankton biomass in the Southern Ocean. Nat Commun 2020; 11:5364. [PMID: 33097697 PMCID: PMC7584623 DOI: 10.1038/s41467-020-19157-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 09/28/2020] [Indexed: 11/08/2022] Open
Abstract
Over the last ten years, satellite and geographically constrained in situ observations largely focused on the northern hemisphere have suggested that annual phytoplankton biomass cycles cannot be fully understood from environmental properties controlling phytoplankton division rates (e.g., nutrients and light), as they omit the role of ecological and environmental loss processes (e.g., grazing, viruses, sinking). Here, we use multi-year observations from a very large array of robotic drifting floats in the Southern Ocean to determine key factors governing phytoplankton biomass dynamics over the annual cycle. Our analysis reveals seasonal phytoplankton accumulation ('blooming') events occurring during periods of declining modeled division rates, an observation that highlights the importance of loss processes in dictating the evolution of the seasonal cycle in biomass. In the open Southern Ocean, the spring bloom magnitude is found to be greatest in areas with high dissolved iron concentrations, consistent with iron being a well-established primary limiting nutrient in this region. Under ice observations show that biomass starts increasing in early winter, well before sea ice begins to retreat. The average theoretical sensitivity of the Southern Ocean to potential changes in seasonal nutrient and light availability suggests that a 10% change in phytoplankton division rate may be associated with a 50% reduction in mean bloom magnitude and annual primary productivity, assuming simple changes in the seasonal magnitude of phytoplankton division rates. Overall, our results highlight the importance of quantifying and accounting for both division and loss processes when modeling future changes in phytoplankton biomass cycles.
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Prity SA, Sajib SA, Das U, Rahman MM, Haider SA, Kabir AH. Arbuscular mycorrhizal fungi mitigate Fe deficiency symptoms in sorghum through phytosiderophore-mediated Fe mobilization and restoration of redox status. PROTOPLASMA 2020; 257:1373-1385. [PMID: 32535729 DOI: 10.1007/s00709-020-01517-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Accepted: 05/05/2020] [Indexed: 05/26/2023]
Abstract
Sustainable management of iron (Fe) deficiency through the microbial association is highly desirable to ensure crop yield. This study elucidates whether and how arbuscular mycorrhizal fungi (AMF) ameliorate Fe deficiency symptoms in sorghum. AMF inoculation showed a significant improvement in plant biomass, chlorophyll score, Fv/Fm (quantum efficiency of photosystem II), and Pi_ABS (photosynthesis performance index), suggesting its potentiality to diminish Fe deficiency symptoms in sorghum. This AMF-driven prevention of Fe deficiency was further supported by the improvement of biochemical stress indicators, such as cell death, electrolyte leakage, hydrogen peroxide, and superoxide anion. In this study, AMF showed a significant increase in phytosiderophore (PS) release as well as Fe and S concentrations in sorghum under Fe deficiency. Quantitative real-time PCR analysis demonstrated the consistent upregulation of SbDMAS2 (deoxymugineic acid synthase 2), SbNAS2 (nicotianamine synthase 2), and SbYS1 (Fe-phytosiderophore transporter yellow stripe) in roots due to AMF with Fe deficiency. It suggests that the enhancement of Fe due to AMF is related to the mobilization of Fe(III)-PS in the rhizosphere supported by the long-distance transport of Fe by SbYS1 transporter in sorghum. Our study further showed that the elevation of S mainly in the presence of AMF possibly enhances the S-containing antioxidant metabolites (Met, Cys, and GSH) as well as enzymes (CAT, SOD, and GR) to counteract H2O2 and O2- for the restoration of redox status in Fe-deprived sorghum. Moreover, S possibly participates in Strategy II responses revealing its crucial role as a signaling molecule for Fe homeostasis in sorghum.
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Affiliation(s)
- Sadia Akter Prity
- Molecular Plant Physiology Laboratory, Department of Botany, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | | | - Urmi Das
- Molecular Plant Physiology Laboratory, Department of Botany, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | - Md Mostafizur Rahman
- Molecular Plant Physiology Laboratory, Department of Botany, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | - Syed Ali Haider
- Molecular Plant Physiology Laboratory, Department of Botany, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | - Ahmad Humayan Kabir
- Molecular Plant Physiology Laboratory, Department of Botany, University of Rajshahi, Rajshahi, 6205, Bangladesh.
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Mausz MA, Segovia M, Larsen A, Berger SA, Egge JK, Pohnert G. High CO 2 concentration and iron availability determine the metabolic inventory in an Emiliania huxleyi-dominated phytoplankton community. Environ Microbiol 2020; 22:3863-3882. [PMID: 32656913 DOI: 10.1111/1462-2920.15160] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 07/08/2020] [Indexed: 11/27/2022]
Abstract
Ocean acidification (OA), a consequence of anthropogenic carbon dioxide (CO2 ) emissions, strongly impacts marine ecosystems. OA also influences iron (Fe) solubility, affecting biogeochemical and ecological processes. We investigated the interactive effects of CO2 and Fe availability on the metabolome response of a natural phytoplankton community. Using mesocosms we exposed phytoplankton to ambient (390 μatm) or future CO2 levels predicted for the year 2100 (900 μatm), combined with ambient (4.5 nM) or high (12 nM) dissolved iron (dFe). By integrating over the whole phytoplankton community, we assigned functional changes based on altered metabolite concentrations. Our study revealed the complexity of phytoplankton metabolism. Metabolic profiles showed three stages in response to treatments and phytoplankton dynamics. Metabolome changes were related to the plankton group contributing respective metabolites, explaining bloom decline and community succession. CO2 and Fe affected metabolic profiles. Most saccharides, fatty acids, amino acids and many sterols significantly correlated with the high dFe treatment at ambient pCO2 . High CO2 lowered the abundance of many metabolites irrespective of Fe. However, sugar alcohols accumulated, indicating potential stress. We demonstrate that not only altered species composition but also changes in the metabolic landscape affecting the plankton community may change as a consequence of future high-CO2 oceans.
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Affiliation(s)
- Michaela A Mausz
- Department for Bioorganic Analytics, Friedrich Schiller University Jena, Lessingstr. 8, Jena, 07743, Germany.,Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (HKI), Beutenbergstr. 11a, Jena, 07745, Germany.,School of Life Sciences, The University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, United Kingdom
| | - María Segovia
- Department of Ecology, Faculty of Sciences, University of Málaga, Bulevar Louis Pasteur s/n, Málaga, 29071, Spain
| | - Aud Larsen
- NORCE Norwegian Research Centre AS, Nygårdsgaten 112, Bergen, 5038, Norway.,Department of Biology, University of Bergen, Thormøhlensgaten 53A/B, Bergen, 5020, Norway
| | - Stella A Berger
- Department of Biology, University of Bergen, Thormøhlensgaten 53A/B, Bergen, 5020, Norway.,Department of Experimental Limnology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Alte Fischerhütte 2, Stechlin, 16775, Germany
| | - Jorun K Egge
- Department of Biology, University of Bergen, Thormøhlensgaten 53A/B, Bergen, 5020, Norway
| | - Georg Pohnert
- Department for Bioorganic Analytics, Friedrich Schiller University Jena, Lessingstr. 8, Jena, 07743, Germany
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Transcriptome Analysis Reveals IsiA-Regulatory Mechanisms Underlying Iron Depletion and Oxidative-Stress Acclimation in Synechocystis sp. Strain PCC 6803. Appl Environ Microbiol 2020; 86:AEM.00517-20. [PMID: 32332138 DOI: 10.1128/aem.00517-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 04/19/2020] [Indexed: 12/22/2022] Open
Abstract
Microorganisms in nature are commonly exposed to various stresses in parallel. The isiA gene encodes an iron stress-induced chlorophyll-binding protein which is significantly induced under iron starvation and oxidative stress. Acclimation of oxidative stress and iron deficiency was investigated using a regulatory mutant of the Synechocystis sp. strain PCC 6803. In this study, the ΔisiA mutant grew more slowly in oxidative-stress and iron depletion conditions compared to the wild-type (WT) counterpart under the same conditions. Thus, we performed transcriptome sequencing (RNA-seq) analysis of the WT strain and the ΔisiA mutant under double-stress conditions to obtain a comprehensive view of isiA-regulated genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses showed significant differences between the WT strain and ΔisiA mutant, mainly related to photosynthesis and the iron-sulfur cluster. The deletion of isiA affects the expression of various genes that are involved in cellular processes and structures, such as photosynthesis, phycobilisome, and the proton-transporting ATPase complex. Weighted gene coexpression network analysis (WGCNA) demonstrated three functional modules in which the turquoise module was negatively correlated with superoxide dismutase (SOD) activity. Coexpression network analysis identified several hub genes of each module. Cotranscriptional PCR and reads coverage using the Integrative Genomics Viewer demonstrated that isiA, isiB, isiC, ssl0461, and dfp belonged to the isi operon. Three sRNAs related to oxidative stress were identified. This study enriches our knowledge of IsiA-regulatory mechanisms under iron deficiency and oxidative stress.IMPORTANCE This study analyzed the impact of isiA deletion on the transcriptomic profile of Synechocystis The isiA gene encodes an iron stress-induced chlorophyll-binding protein, which is significantly induced under iron starvation. The deletion of isiA affects the expression of various genes that are involved in photosynthesis and ABC transporters. WGCNA revealed three functional modules in which the blue module was correlated with oxidative stress. We further demonstrated that the isi operon contained the following five genes: isiA, isiB, isiC, ssl0461, and dfp by cotranscriptional PCR. Three sRNAs were identified that were related to oxidative stress. This study enhances our knowledge of IsiA-regulatory mechanisms under iron deficiency and oxidative stress.
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Rizkallah MR, Frickenhaus S, Trimborn S, Harms L, Moustafa A, Benes V, Gäbler-Schwarz S, Beszteri S. Deciphering Patterns of Adaptation and Acclimation in the Transcriptome of Phaeocystis antarctica to Changing Iron Conditions 1. JOURNAL OF PHYCOLOGY 2020; 56:747-760. [PMID: 32068264 DOI: 10.1111/jpy.12979] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 01/21/2020] [Indexed: 06/10/2023]
Abstract
The haptophyte Phaeocystis antarctica is endemic to the Southern Ocean, where iron supply is sporadic and its availability limits primary production. In iron fertilization experiments, P. antarctica showed a prompt and steady increase in cell abundance compared to heavily silicified diatoms along with enhanced colony formation. Here we utilized a transcriptomic approach to investigate molecular responses to alleviation of iron limitation in P. antarctica. We analyzed the transcriptomic response before and after (14 h, 24 h and 72 h) iron addition to a low-iron acclimated culture. After iron addition, we observed indicators of a quick reorganization of cellular energetics, from carbohydrate catabolism and mitochondrial energy production to anabolism. In addition to typical substitution responses from an iron-economic toward an iron-sufficient state for flavodoxin (ferredoxin) and plastocyanin (cytochrome c6 ), we found other genes utilizing the same strategy involved in nitrogen assimilation and fatty acid desaturation. Our results shed light on a number of adaptive mechanisms that P. antarctica uses under low iron, including the utilization of a Cu-dependent ferric reductase system and indication of mixotrophic growth. The gene expression patterns underpin P. antarctica as a quick responder to iron addition.
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Affiliation(s)
| | - Stephan Frickenhaus
- Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570, Bremerhaven, Germany
- Centre for Industrial Mathematics, University of Bremen, Bibliothekstrasse 1, 28359 Postfach 330440, 28334, Bremen, Germany
| | - Scarlett Trimborn
- Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570, Bremerhaven, Germany
- Department of Marine Botany, University of Bremen, Bibliothekstrasse 1, 28359 Postfach 330440, 28334, Bremen, Germany
| | - Lars Harms
- Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570, Bremerhaven, Germany
- Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB), Ammerländer Herrstrasse 231, 26129, Oldenburg, Germany
| | - Ahmed Moustafa
- Department of Biology, American University in Cairo, P.O. Box 74, 11835, Cairo, Egypt
| | - Vladimir Benes
- European Molecular Biology Laboratory, Meyerhofstraße 1, 69117, Heidelberg, Germany
| | - Steffi Gäbler-Schwarz
- Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570, Bremerhaven, Germany
| | - Sara Beszteri
- Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570, Bremerhaven, Germany
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Kabir AH, Debnath T, Das U, Prity SA, Haque A, Rahman MM, Parvez MS. Arbuscular mycorrhizal fungi alleviate Fe-deficiency symptoms in sunflower by increasing iron uptake and its availability along with antioxidant defense. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2020; 150:254-262. [PMID: 32171164 DOI: 10.1016/j.plaphy.2020.03.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 03/05/2020] [Accepted: 03/06/2020] [Indexed: 05/26/2023]
Abstract
Iron (Fe)-deficiency causes chlorosis and growth inhibition in sunflower, an important commercial crop. This study examines whether and how arbuscular mycorrhizal fungi (AMF) ameliorate Fe-deficiency symptoms in Fe-deficiency sensitive sunflower plants. AMF supplementation showed a significant improvement in plant biomass, chlorophyll score, Fv/Fm (quantum efficiency of photosystem II), and Pi_ABS (photosynthesis performance index), suggesting its beneficial effect under Fe deficiency. This AM-driven amelioration of Fe deficiency was further supported by the improvement of biochemical stress indicators, such as cell death, electrolyte leakage, superoxide anion, and hydrogen peroxide. In this study, the AMF supplementations resulted in significant improvement in Fe as well as Zn concentrations in root and shoot of sunflower under Fe deficiency. One of the primary Strategy-I responses, ferric reductase activity along with the expression of its respective gene (HaFRO1), significantly increased in roots due to AMF ensuring Fe availability in the rhizosphere under Fe deficiency. Our qPCR analysis also showed a significant upregulation of HaIRT1, HaNramp1, and HaZIP1 in roots of sunflower in the presence of AMF, suggesting that Fe and Zn transporters are concurrently involved with AMF-mediated alleviation of Fe deficiency. Further, AMF accelerates the activities of CAT and SOD, predominantly in roots to protect sunflower plants from Fe-deficiency reactive oxygen species (ROS). This study unveils the mechanistic basis of AMF to limit Fe deficiency retardation in sunflower.
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Affiliation(s)
- Ahmad Humayan Kabir
- Molecular Plant Physiology Laboratory, Department of Botany, University of Rajshahi, Rajshahi, 6205, Bangladesh.
| | - Taposhi Debnath
- Molecular Plant Physiology Laboratory, Department of Botany, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | - Urmi Das
- Molecular Plant Physiology Laboratory, Department of Botany, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | - Sadia Akter Prity
- Molecular Plant Physiology Laboratory, Department of Botany, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | - Ariful Haque
- Institute of Biological Sciences, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | - Md Motiur Rahman
- Department of Genetic Engineering and Biotechnology, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | - Md Sarwar Parvez
- Molecular Plant Physiology Laboratory, Department of Botany, University of Rajshahi, Rajshahi, 6205, Bangladesh
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Zhou J, Zhang BY, Yu K, Du XP, Zhu JM, Zeng YH, Cai ZH. Functional profiles of phycospheric microorganisms during a marine dinoflagellate bloom. WATER RESEARCH 2020; 173:115554. [PMID: 32028248 DOI: 10.1016/j.watres.2020.115554] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 12/14/2019] [Accepted: 01/25/2020] [Indexed: 06/10/2023]
Abstract
Harmful algal blooms (HABs) are an ecological concern but relatively few studies have investigated the functional potential of bacterioplankton over a complete algal bloom cycle, which is critical for determining their contribution to the fate of algal blooms. To address this point, we carried out a time-series metagenomic analysis of the functional features of microbial communities at three different Gymnodinium catenatum bloom stages (pre-, peak-, and post-bloom). Different microbial composition were observed during the blooming stages. The environmental parameters and correlation networks co-contribute to microbial variability, and the former explained 38.4% of total variations of the bacterioplankton community composition. Functionally, a range of pathways involved in carbon, nitrogen, phosphorus and sulfur cycling were significantly different during the various HAB stages. Genes associated with carbohydrate-active enzymes, denitrification, and iron oxidation were enriched at the pre-bloom stage; genes involved in reductive citrate cycle for carbon fixation, carbon degradation, nitrification and phosphate transport were enhanced at the peak stage; and relative gene abundance related to sulfur oxidation, vitamin synthesis, and iron transport and storage was increased at the post-bloom stage. The ecological linkage analysis has shown that microbial functional potential especially the C/P/Fe metabolism were significantly linked to the fate of the algal blooms. Taken together, our results demonstrated that microorganisms displayed successional patterns not only at the community level, but also in the metabolic potential on HAB's progression. This work contributes to a growing understanding of microbial structural elasticity and functional plasticity and shed light on the potential mechanisms of microbial-mediated HAB trajectory.
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Affiliation(s)
- Jin Zhou
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, The Shenzhen International Graduate School, Tsinghua University, Shenzhen, China; The Shenzhen International Graduate School, Tsinghua University, Shenzhen, China
| | - Bo-Ya Zhang
- The School of Environment and Energy, Graduate School at Shenzhen, Peking University, Guangdong Province, Shenzhen, China
| | - Ke Yu
- The School of Environment and Energy, Graduate School at Shenzhen, Peking University, Guangdong Province, Shenzhen, China
| | - Xiao-Peng Du
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, The Shenzhen International Graduate School, Tsinghua University, Shenzhen, China; The Shenzhen International Graduate School, Tsinghua University, Shenzhen, China
| | - Jian-Ming Zhu
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, The Shenzhen International Graduate School, Tsinghua University, Shenzhen, China; The Shenzhen International Graduate School, Tsinghua University, Shenzhen, China
| | - Yan-Hua Zeng
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, The Shenzhen International Graduate School, Tsinghua University, Shenzhen, China; The Shenzhen International Graduate School, Tsinghua University, Shenzhen, China
| | - Zhong-Hua Cai
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, The Shenzhen International Graduate School, Tsinghua University, Shenzhen, China; The Shenzhen International Graduate School, Tsinghua University, Shenzhen, China.
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Rahman MA, Parvin M, Das U, Ela EJ, Lee SH, Lee KW, Kabir AH. Arbuscular Mycorrhizal Symbiosis Mitigates Iron (Fe)-Deficiency Retardation in Alfalfa ( Medicago sativa L.) Through the Enhancement of Fe Accumulation and Sulfur-Assisted Antioxidant Defense. Int J Mol Sci 2020; 21:E2219. [PMID: 32210097 PMCID: PMC7139841 DOI: 10.3390/ijms21062219] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 03/16/2020] [Accepted: 03/20/2020] [Indexed: 11/16/2022] Open
Abstract
Iron (Fe)-deficiency is one of the major constraints affecting growth, yield and nutritional quality in plants. This study was performed to elucidate how arbuscular mycorrhizal fungi (AMF) alleviate Fe-deficiency retardation in alfalfa (Medicago sativa L.). AMF supplementation improved plant biomass, chlorophyll score, Fv/Fm (quantum efficiency of photosystem II), and Pi_ABS (photosynthesis performance index), and reduced cell death, electrolyte leakage, and hydrogen peroxide accumulation in alfalfa. Moreover, AMF enhanced ferric chelate reductase activity as well as Fe, Zn, S and P in alfalfa under Fe-deficiency. Although Fe-transporters (MsIRT1 and MsNramp1) did not induce in root but MsFRO1 significantly induced by AMF under Fe deficiency in roots, suggesting that AMF-mediated Fe enhancement is related to the bioavailability of Fe at rhizosphere/root apoplast rather than the upregulation of Fe transporters under Fe deficiency in alfalfa. Several S-transporters (MsSULTR1;1, MsSULTR1;2, MsSULTR1;3, and MsSULTR3;1) markedly increased following AMF supplementation with or without Fe-deficiency alfalfa. Our study further suggests that Fe uptake system is independently influenced by AMF regardless of the S status in alfalfa. However, the increase of S in alfalfa is correlated with the elevation of GR and S-metabolites (glutathione and cysteine) associated with antioxidant defense under Fe deficiency.
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Affiliation(s)
- Md. Atikur Rahman
- Grassland and Forage Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Korea; (M.A.R.); (S.-H.L.)
| | - Monika Parvin
- Molecular Plant Physiology Laboratory, Department of Botany, University of Rajshahi, Rajshahi 6205, Bangladesh; (M.P.); (U.D.); (A.H.K.)
| | - Urmi Das
- Molecular Plant Physiology Laboratory, Department of Botany, University of Rajshahi, Rajshahi 6205, Bangladesh; (M.P.); (U.D.); (A.H.K.)
| | - Esrat Jahan Ela
- Molecular Plant Physiology Laboratory, Department of Botany, University of Rajshahi, Rajshahi 6205, Bangladesh; (M.P.); (U.D.); (A.H.K.)
| | - Sang-Hoon Lee
- Grassland and Forage Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Korea; (M.A.R.); (S.-H.L.)
| | - Ki-Won Lee
- Grassland and Forage Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Korea; (M.A.R.); (S.-H.L.)
| | - Ahmad Humayan Kabir
- Molecular Plant Physiology Laboratory, Department of Botany, University of Rajshahi, Rajshahi 6205, Bangladesh; (M.P.); (U.D.); (A.H.K.)
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Yoshida K, Nakamura S, Nishioka J, Hooker SB, Suzuki K. Community composition and photosynthetic physiology of phytoplankton in the western subarctic Pacific near the Kuril Islands with special reference to iron availability. JOURNAL OF GEOPHYSICAL RESEARCH. BIOGEOSCIENCES 2020; 125:e2019JG005525. [PMID: 33101822 PMCID: PMC7580765 DOI: 10.1029/2019jg005525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Accepted: 02/08/2020] [Indexed: 06/11/2023]
Abstract
The western subarctic Pacific (WSP) is known as one of the most productive regions among the world's oceans in spring. However, its oceanic waters are also known as a High Nutrient, Low Chlorophyll (HNLC) region during summer due to low iron (Fe) availability in seawater. Indeed, recent studies have demonstrated that the distribution of Fe in the WSP is complex and heterogeneous. This study thus investigated the effects of Fe availability on the community composition and photophysiology of surface phytoplankton from coastal to offshore waters in the WSP in the summer of 2014. Although relatively high concentrations (>2 mg m-3) of chlorophyll (chl) a were found in the Sea of Okhotsk and some coastal waters, low chl a concentrations (<1 mg m-3) were commonly observed in offshore waters. Based on dissolved Fe and macronutrient concentrations, we deduced that low Fe availability limited phytoplankton growth in offshore waters, whereas low silicate and/or nitrate levels limited growth in the shelf areas. Scanning electron microscopy also revealed that the centric diatom Chaetoceros exclusively dominated the diatom assemblages in the shelf and coexisted with pennate diatoms in offshore waters, respectively. Primary productivity in surface waters was negatively correlated with the bottom of the euphotic layer or the light saturation index of the photosynthesis-irradiance curve, which indicates that the phytoplankton assemblages were well acclimated to in situ light conditions regardless of the water masses.
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Affiliation(s)
- Kazuhiro Yoshida
- Graduate School of Environmental Science, Hokkaido University, North 10 West 5, Kita-Ku, Sapporo, Hokkaido 060-0810, Japan
| | - Suzu Nakamura
- Graduate School of Environmental Science, Hokkaido University, North 10 West 5, Kita-Ku, Sapporo, Hokkaido 060-0810, Japan
| | - Jun Nishioka
- Graduate School of Environmental Science, Hokkaido University, North 10 West 5, Kita-Ku, Sapporo, Hokkaido 060-0810, Japan
- Pan-Okhotsk Research Center, Institute for Low Temperature Science, Hokkaido University, North 19 West 8, Kita-Ku, Sapporo, Hokkaido 060-0819, Japan
| | - Stanford B. Hooker
- Goddard Space Flight Center, National Aeronautical and Space Administration, 8880 Greenbelt Rd, Greenbelt, MD 20771, USA
| | - Koji Suzuki
- Graduate School of Environmental Science, Hokkaido University, North 10 West 5, Kita-Ku, Sapporo, Hokkaido 060-0810, Japan
- Faculty of Environmental Earth Science, Hokkaido University, North 10 West 5, Kita-Ku, Sapporo, Hokkaido 060-0810, Japan
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Cao P, Cao D, Si L, Su X, Tian L, Chang W, Liu Z, Zhang X, Li M. Structural basis for energy and electron transfer of the photosystem I-IsiA-flavodoxin supercomplex. NATURE PLANTS 2020; 6:167-176. [PMID: 32042157 DOI: 10.1038/s41477-020-0593-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 01/06/2020] [Indexed: 05/10/2023]
Abstract
Under iron-deficiency stress, which occurs frequently in natural aquatic environments, cyanobacteria reduce the amount of iron-enriched proteins, including photosystem I (PSI) and ferredoxin (Fd), and upregulate the expression of iron-stress-induced proteins A and B (IsiA and flavodoxin (Fld)). Multiple IsiAs function as the peripheral antennae that encircle the PSI core, whereas Fld replaces Fd as the electron receptor of PSI. Here, we report the structures of the PSI3-IsiA18-Fld3 and PSI3-IsiA18 supercomplexes from Synechococcus sp. PCC 7942, revealing features that are different from the previously reported PSI structures, and a sophisticated pigment network that involves previously unobserved pigment molecules. Spectroscopic results demonstrated that IsiAs are efficient light harvesters for PSI. Three Flds bind symmetrically to the trimeric PSI core-we reveal the detailed interaction and the electron transport path between PSI and Fld. Our results provide a structural basis for understanding the mechanisms of light harvesting, energy transfer and electron transport of cyanobacterial PSI under stressed conditions.
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Affiliation(s)
- Peng Cao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
| | - Duanfang Cao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
| | - Long Si
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
- University of Chinese Academy of Sciences, Beijing, P. R. China
| | - Xiaodong Su
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
| | - Lijin Tian
- Institute of Botany, Chinese Academy of Sciences, Beijing, P. R. China
| | - Wenrui Chang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
- University of Chinese Academy of Sciences, Beijing, P. R. China
| | - Zhenfeng Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
- University of Chinese Academy of Sciences, Beijing, P. R. China
| | - Xinzheng Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China.
- University of Chinese Academy of Sciences, Beijing, P. R. China.
- Center for Biological Imaging, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China.
| | - Mei Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China.
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Teoh F, Shah B, Ostrowski M, Paulsen I. Comparative membrane proteomics reveal contrasting adaptation strategies for coastal and oceanic marine Synechococcus cyanobacteria. Environ Microbiol 2020; 22:1816-1828. [PMID: 31769166 DOI: 10.1111/1462-2920.14876] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 10/29/2019] [Accepted: 11/21/2019] [Indexed: 11/27/2022]
Abstract
Marine cyanobacteria genus Synechococcus are among the most abundant and widespread primary producers in the open ocean. Synechococcus strains belonging to different clades have adapted distinct strategies for growth and survival across a range of marine conditions. Clades I and IV are prevalent in colder, mesotrophic, coastal waters, while clades II and III prefer warm, oligotrophic open oceans. To gain insight into the cellular resources these unicellular organisms invest in adaptation strategies we performed shotgun membrane proteomics of four Synechococcus spp. strains namely CC9311 (clade I), CC9605 (clade II), WH8102 (clade III) and CC9902 (clade IV). Comparative membrane proteomes analysis demonstrated that CC9902 and WH8102 showed high resource allocation for phosphate uptake, accounting for 44% and 38% of overall transporter protein expression of the species. WH8102 showed high expression of the iron uptake ATP-binding cassette binding protein FutA, suggesting that a high binding affinity for iron is possibly a key adaptation strategy for some strains in oligotrophic ocean environments. One protein annotated as a phosphatase 2c (Sync_2505 and Syncc9902_0387) was highly expressed in the coastal mesotrophic strains CC9311 and CC9902, constituting 14%-16% of total membrane protein, indicating a vital, but undefined function, for strains living in temperate mesotrophic environments.
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Affiliation(s)
- Fallen Teoh
- Department of Molecular Sciences, Macquarie University, Sydney, Australia
| | - Bhumika Shah
- Department of Molecular Sciences, Macquarie University, Sydney, Australia
| | - Martin Ostrowski
- Department of Molecular Sciences, Macquarie University, Sydney, Australia
| | - Ian Paulsen
- Department of Molecular Sciences, Macquarie University, Sydney, Australia
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48
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Comparative photosynthetic responses of Norway spruce and Scots pine seedlings to prolonged water deficiency. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2019; 201:111659. [PMID: 31698219 DOI: 10.1016/j.jphotobiol.2019.111659] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 10/02/2019] [Accepted: 10/19/2019] [Indexed: 12/22/2022]
Abstract
Stressors of different natures, including drought stress, substantially compromise the ability of plants to effectively and safely utilize light energy. We investigated the influence of water stress on the photosynthetic processes in Picea abies and Pinus sylvestris, two species with contrasting drought sensitivities. Spruce and pine seedlings were exposed to polyethylene glycol 6000-induced water deficits of different intensities and durations. The maintenance of photosystem I (PSI) oxidation in spruce required increased photosynthetic control and led to the increased reduction of the plastoquinone pool, which was not the case in pine seedlings. As a result of increased excitation pressure, photosystem II (PSII) inactivation was observed in spruce plants, whereas in pine, the decreased PSII photochemistry was likely due to sustained non-photochemical quenching. Downregulation of PSII photochemistry and maintenance of PSI in an oxidized state were linked with the prevention of oxidative stress, even under severe water deficit. The decreased photosynthetic pigment content and photosynthetic gene expression suggested the coordinated downregulation of photosynthetic apparatus components under water stress to reduce light energy absorption. In summary, the observed adaptative mechanisms of pine and spruce to water stress may be similar to the well-studied adaptative mechanisms to winter stress, which may indicate the universality of protective mechanisms under various stresses in conifers.
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Abstract
Diatoms can access inorganic iron with remarkable efficiency, but this process is contingent on carbonate ion concentration. As ocean acidification reduces carbonate concentration, inorganic iron uptake may be discouraged in favor of carbonate-independent uptake. We report details of an iron assimilation process that needs no carbonate but requires exogenous compounds produced by cooccurring organisms. We show this process to be critical for diatom growth at high siderophore concentrations, but ineffective at acquiring iron from low-affinity organic chelators or lithogenic particulates. Understanding the caveats associated with iron source preference in diatoms will help predict the impacts of climate change on microbial community structure in high-nitrate low-chlorophyll ecosystems. Iron uptake by diatoms is a biochemical process with global biogeochemical implications. In large regions of the surface ocean diatoms are both responsible for the majority of primary production and frequently experiencing iron limitation of growth. The strategies used by these phytoplankton to extract iron from seawater constrain carbon flux into higher trophic levels and sequestration into sediments. In this study we use reverse genetic techniques to target putative iron-acquisition genes in the model pennate diatom Phaeodactylum tricornutum. We describe components of a reduction-dependent siderophore acquisition pathway that relies on a bacterial-derived receptor protein and provides a viable alternative to inorganic iron uptake under certain conditions. This form of iron uptake entails a close association between diatoms and siderophore-producing organisms during low-iron conditions. Homologs of these proteins are found distributed across diatom lineages, suggesting the significance of siderophore utilization by diatoms in the marine environment. Evaluation of specific proteins enables us to confirm independent iron-acquisition pathways in diatoms and characterize their preferred substrates. These findings refine our mechanistic understanding of the multiple iron-uptake systems used by diatoms and help us better predict the influence of iron speciation on taxa-specific iron bioavailability.
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Zhang F, Hong H, Kranz SA, Shen R, Lin W, Shi D. Proteomic responses to ocean acidification of the marine diazotroph Trichodesmium under iron-replete and iron-limited conditions. PHOTOSYNTHESIS RESEARCH 2019; 142:17-34. [PMID: 31077001 DOI: 10.1007/s11120-019-00643-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 04/30/2019] [Indexed: 05/19/2023]
Abstract
Growth and dinitrogen (N2) fixation of the globally important diazotrophic cyanobacteria Trichodesmium are often limited by iron (Fe) availability in surface seawaters. To systematically examine the combined effects of Fe limitation and ocean acidification (OA), T. erythraeum strain IMS101 was acclimated to both Fe-replete and Fe-limited concentrations under ambient and acidified conditions. Proteomic analysis showed that OA affected a wider range of proteins under Fe-limited conditions compared to Fe-replete conditions. OA also led to an intensification of Fe deficiency in key cellular processes (e.g., photosystem I and chlorophyll a synthesis) in already Fe-limited T. erythraeum. This is a result of reallocating Fe from these processes to Fe-rich nitrogenase to compensate for the suppressed N2 fixation. To alleviate the Fe shortage, the diazotroph adopts a series of Fe-based economic strategies (e.g., upregulating Fe acquisition systems for organically complexed Fe and particulate Fe, replacing ferredoxin by flavodoxin, and using alternative electron flow pathways to produce ATP). This was more pronounced under Fe-limited-OA conditions than under Fe limitation only. Consequently, OA resulted in a further decrease of N2- and carbon-fixation rates in Fe-limited T. erythraeum. In contrast, Fe-replete T. erythraeum induced photosystem I (PSI) expression to potentially enhance the PSI cyclic flow for ATP production to meet the higher demand for energy to cope with the stress caused by OA. Our study provides mechanistic insight into the holistic response of the globally important N2-fixing marine cyanobacteria Trichodesmium to acidified and Fe-limited conditions of future oceans.
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Affiliation(s)
- Futing Zhang
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Haizheng Hong
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, People's Republic of China
- Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, Xiamen University, Xiamen, Fujian, People's Republic of China
- College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Sven A Kranz
- Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, FL, 32306, USA
| | - Rong Shen
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Wenfang Lin
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Dalin Shi
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, People's Republic of China.
- Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, Xiamen University, Xiamen, Fujian, People's Republic of China.
- College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, People's Republic of China.
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