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Yu Z, Wang Z, Liu L. Electrophysiological techniques in marine microalgae study: A new perspective for harmful algal bloom (HAB) research. HARMFUL ALGAE 2024; 134:102629. [PMID: 38705615 DOI: 10.1016/j.hal.2024.102629] [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: 01/07/2024] [Revised: 04/11/2024] [Accepted: 04/15/2024] [Indexed: 05/07/2024]
Abstract
Electrophysiological techniques, by measuring bioelectrical signals and ion channel activities in tissues and cells, are now widely utilized to study ion channel-related physiological functions and their underlying mechanisms. Electrophysiological techniques have been extensively employed in the investigation of animals, plants, and microorganisms; however, their application in marine algae lags behind that in other organisms. In this paper, we present an overview of current electrophysiological techniques applicable to algae while reviewing the historical usage of such techniques in this field. Furthermore, we explore the potential specific applications of electrophysiological technology in harmful algal bloom (HAB) research. The application prospects in the studies of stress tolerance, competitive advantage, nutrient absorption, toxin synthesis and secretion by HAB microalgae are discussed and anticipated herein with the aim of providing novel perspectives on HAB investigations.
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Affiliation(s)
- Zhiming Yu
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory of Marine Ecology and Environmental Science, Laoshan Laboratory, Qingdao, 266237, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China.
| | - Zhongshi Wang
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory of Marine Ecology and Environmental Science, Laoshan Laboratory, Qingdao, 266237, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Lidong Liu
- The Djavad Mowafaghian Centre for Brian Health and Department of Medicine, University of British Columbia, Vancouver, BC, Canada
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2
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Sandoval-Gil JM, Ruiz JM, Marín-Guirao L. Advances in understanding multilevel responses of seagrasses to hypersalinity. MARINE ENVIRONMENTAL RESEARCH 2023; 183:105809. [PMID: 36435174 DOI: 10.1016/j.marenvres.2022.105809] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 11/07/2022] [Accepted: 11/08/2022] [Indexed: 06/16/2023]
Abstract
Human- and nature-induced hypersaline conditions in coastal systems can lead to profound alterations of the structure and vitality of seagrass meadows and their socio-ecological benefits. In the last two decades, recent research efforts (>50 publications) have contributed significantly to unravel the physiological basis underlying the seagrass-hypersalinity interactions, although most (∼70%) are limited to few species (e.g. Posidonia oceanica, Zostera marina, Thalassia testudinum, Cymodocea nodosa). Variables related to photosynthesis and carbon metabolism are among the most prevalent in the literature, although other key metabolic processes such as plant water relations and responses at molecular (i.e. gene expression) and ultrastructure level are attracting attention. This review emphasises all these latest insights, offering an integrative perspective on the interplay among biological responses across different functional levels (from molecular to clonal structure), and their interaction with biotic/abiotic factors including those related to climate change. Other issues such as the role of salinity in driving the evolutionary trajectory of seagrasses, their acclimation mechanisms to withstand salinity increases or even the adaptive properties of populations that have historically lived under hypersaline conditions are also included. The pivotal role of the costs and limits of phenotypic plasticity in the successful acclimation of marine plants to hypersalinity is also discussed. Finally, some lines of research are proposed to fill the remaining knowledge gaps.
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Affiliation(s)
- Jose Miguel Sandoval-Gil
- Universidad Autónoma de Baja California (UABC), Instituto de Investigaciones Oceanológicas (IIO), Marine Botany Research Group, Ensenada, Baja California, 22860, Mexico
| | - Juan M Ruiz
- Seagrass Ecology Group, Spanish Institute of Oceanography (IEO-CSIC), C/ Varadero s/n, 30740 San Pedro del Pinatar, Murcia, Spain
| | - Lázaro Marín-Guirao
- Seagrass Ecology Group, Spanish Institute of Oceanography (IEO-CSIC), C/ Varadero s/n, 30740 San Pedro del Pinatar, Murcia, Spain.
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3
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Ye JY, Tian WH, Jin CW. Nitrogen in plants: from nutrition to the modulation of abiotic stress adaptation. STRESS BIOLOGY 2022; 2:4. [PMID: 37676383 PMCID: PMC10441927 DOI: 10.1007/s44154-021-00030-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Accepted: 12/14/2021] [Indexed: 09/08/2023]
Abstract
Nitrogen is one of the most important nutrient for plant growth and development; it is strongly associated with a variety of abiotic stress responses. As sessile organisms, plants have evolved to develop efficient strategies to manage N to support growth when exposed to a diverse range of stressors. This review summarizes the recent progress in the field of plant nitrate (NO3-) and ammonium (NH4+) uptake, which are the two major forms of N that are absorbed by plants. We explore the intricate relationship between NO3-/NH4+ and abiotic stress responses in plants, focusing on stresses from nutrient deficiencies, unfavorable pH, ions, and drought. Although many molecular details remain unclear, research has revealed a number of core signaling regulators that are associated with N-mediated abiotic stress responses. An in-depth understanding and exploration of the molecular processes that underpin the interactions between N and abiotic stresses is useful in the design of effective strategies to improve crop growth, development, and productivity.
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Affiliation(s)
- Jia Yuan Ye
- State Key Laboratory of Plant Physiology and Biochemistry, College of Natural Resources and Environmental Science, Zhejiang University, Hangzhou, 310058, China
| | - Wen Hao Tian
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Zhejiang, 310006, Hangzhou, China.
| | - Chong Wei Jin
- State Key Laboratory of Plant Physiology and Biochemistry, College of Natural Resources and Environmental Science, Zhejiang University, Hangzhou, 310058, China.
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Britto DT, Coskun D, Kronzucker HJ. Potassium physiology from Archean to Holocene: A higher-plant perspective. JOURNAL OF PLANT PHYSIOLOGY 2021; 262:153432. [PMID: 34034042 DOI: 10.1016/j.jplph.2021.153432] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 04/22/2021] [Accepted: 04/22/2021] [Indexed: 05/27/2023]
Abstract
In this paper, we discuss biological potassium acquisition and utilization processes over an evolutionary timescale, with emphasis on modern vascular plants. The quintessential osmotic and electrical functions of the K+ ion are shown to be intimately tied to K+-transport systems and membrane energization. Several prominent themes in plant K+-transport physiology are explored in greater detail, including: (1) channel mediated K+ acquisition by roots at low external [K+]; (2) K+ loading of root xylem elements by active transport; (3) variations on the theme of K+ efflux from root cells to the extracellular environment; (4) the veracity and utility of the "affinity" concept in relation to transport systems. We close with a discussion of the importance of plant-potassium relations to our human world, and current trends in potassium nutrition from farm to table.
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Affiliation(s)
- Dev T Britto
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada; School of BioSciences, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Devrim Coskun
- Département de Phytologie, Faculté des Sciences de l'Agriculture et de l'Alimentation (FSAA), Université Laval, Québec, QC, G1V 0A6, Canada
| | - Herbert J Kronzucker
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada; School of BioSciences, The University of Melbourne, Parkville, Victoria, 3010, Australia.
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Miller CA, Kelley AL. Alkalinity cycling and carbonate chemistry decoupling in seagrass mystify processes of acidification mitigation. Sci Rep 2021; 11:13500. [PMID: 34188095 PMCID: PMC8241997 DOI: 10.1038/s41598-021-92771-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 06/16/2021] [Indexed: 11/18/2022] Open
Abstract
The adverse conditions of acidification on sensitive marine organisms have led to the investigation of bioremediation methods as a way to abate local acidification. This phytoremediation, by macrophytes, is expected to reduce the severity of acidification in nearshore habitats on short timescales. Characterizing the efficacy of phytoremediation can be challenging as residence time, tidal mixing, freshwater input, and a limited capacity to fully constrain the carbonate system can lead to erroneous conclusions. Here, we present in situ observations of carbonate chemistry relationships to seagrass habitats by comparing dense (DG), patchy (PG), and no grass (NG) Zostera marina pools in the high intertidal experiencing intermittent flooding. High-frequency measurements of pH, alkalinity (TA), and total-CO2 elucidate extreme diel cyclicity in all parameters. The DG pool displayed frequent decoupling between pH and aragonite saturation state (Ωarg) suggesting pH-based inferences of acidification remediation by seagrass can be misinterpreted as pH and Ωarg can be independent stressors for some bivalves. Estimates show the DG pool had an integrated ΔTA of 550 μmol kg−1 over a 12 h period, which is ~ 60% > the PG and NG pools. We conclude habitats with mixed photosynthesizers (i.e., PG pool) result in less decoupling between pH and Ωarg.
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Affiliation(s)
- Cale A Miller
- Department of Evolution and Ecology, University of California Davis, Davis, CA, 95616, USA. .,College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA.
| | - Amanda L Kelley
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA
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Rubio L, García-Pérez D, Davies JM, Fernández JA. Short-Term Response of Cytosolic N O 3 - to Inorganic Carbon Increase in Posidonia oceanica Leaf Cells. FRONTIERS IN PLANT SCIENCE 2020; 11:955. [PMID: 32670341 PMCID: PMC7330836 DOI: 10.3389/fpls.2020.00955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 06/10/2020] [Indexed: 06/11/2023]
Abstract
The concentration of CO2 in the atmosphere has increased over the past 200 years and is expected to continue rising in the next 50 years at a rate of 3 ppm·year-1. This increase has led to a decrease in seawater pH that has changed inorganic carbon chemical speciation, increasing the dissolved HC O 3 - . Posidonia oceanica is a marine angiosperm that uses HC O 3 - as an inorganic carbon source for photosynthesis. An important side effect of the direct uptake of HC O 3 - is the diminution of cytosolic Cl- (Cl-c) in mesophyll leaf cells due to the efflux through anion channels and, probably, to intracellular compartmentalization. Since anion channels are also permeable to N O 3 - we hypothesize that high HC O 3 - , or even CO2, would also promote a decrease of cytosolic N O 3 - ( N O 3 - c ). In this work we have used N O 3 - - and Cl--selective microelectrodes for the continuous monitoring of the cytosolic concentration of both anions in P. oceanica leaf cells. Under light conditions, mesophyll leaf cells showed a N O 3 - c of 5.7 ± 0.2 mM, which rose up to 7.2 ± 0.6 mM after 30 min in the dark. The enrichment of natural seawater (NSW) with 3 mM NaHCO3 caused both a N O 3 - c decrease of 1 ± 0.04 mM and a Cl c - decrease of 3.5 ± 0.1 mM. The saturation of NSW with 1000 ppm CO2 also produced a diminution of the N O 3 - c , but lower (0.4 ± 0.07 mM). These results indicate that the rise of dissolved inorganic carbon ( HC O 3 - or CO2) in NSW would have an effect on the cytosolic anion homeostasis mechanisms in P. oceanica leaf cells. In the presence of 0.1 mM ethoxyzolamide, the plasma membrane-permeable carbonic anhydrase inhibitor, the CO2-induced cytosolic N O 3 - diminution was much lower (0.1 ± 0.08 mM), pointing to HC O 3 - as the inorganic carbon species that causes the cytosolic N O 3 - leak. The incubation of P. oceanica leaf pieces in 3 mM HC O 3 - -enriched NSW triggered a short-term external N O 3 - net concentration increase consistent with the N O 3 - c leak. As a consequence, the cytosolic N O 3 - diminution induced in high inorganic carbon could result in both the decrease of metabolic N flux and the concomitant biomass N impoverishment in P. oceanica and, probably, in other aquatic plants.
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Affiliation(s)
- Lourdes Rubio
- Departamento de Botánica y Fisiología Vegetal, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
| | - Delia García-Pérez
- Departamento de Botánica y Fisiología Vegetal, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
| | - Julia M. Davies
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - José A. Fernández
- Departamento de Botánica y Fisiología Vegetal, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
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Raddatz N, Morales de los Ríos L, Lindahl M, Quintero FJ, Pardo JM. Coordinated Transport of Nitrate, Potassium, and Sodium. FRONTIERS IN PLANT SCIENCE 2020; 11:247. [PMID: 32211003 PMCID: PMC7067972 DOI: 10.3389/fpls.2020.00247] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 02/18/2020] [Indexed: 05/19/2023]
Abstract
Potassium (K+) and nitrogen (N) are essential nutrients, and their absorption and distribution within the plant must be coordinated for optimal growth and development. Potassium is involved in charge balance of inorganic and organic anions and macromolecules, control of membrane electrical potential, pH homeostasis and the regulation of cell osmotic pressure, whereas nitrogen is an essential component of amino acids, proteins, and nucleic acids. Nitrate (NO3 -) is often the primary nitrogen source, but it also serves as a signaling molecule to the plant. Nitrate regulates root architecture, stimulates shoot growth, delays flowering, regulates abscisic acid-independent stomata opening, and relieves seed dormancy. Plants can sense K+/NO3 - levels in soils and adjust accordingly the uptake and root-to-shoot transport to balance the distribution of these ions between organs. On the other hand, in small amounts sodium (Na+) is categorized as a "beneficial element" for plants, mainly as a "cheap" osmolyte. However, at high concentrations in the soil, Na+ can inhibit various physiological processes impairing plant growth. Hence, plants have developed specific mechanisms to transport, sense, and respond to a variety of Na+ conditions. Sodium is taken up by many K+ transporters, and a large proportion of Na+ ions accumulated in shoots appear to be loaded into the xylem by systems that show nitrate dependence. Thus, an adequate supply of mineral nutrients is paramount to reduce the noxious effects of salts and to sustain crop productivity under salt stress. In this review, we will focus on recent research unraveling the mechanisms that coordinate the K+-NO3 -; Na+-NO3 -, and K+-Na+ transports, and the regulators controlling their uptake and allocation.
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Affiliation(s)
| | | | | | | | - José M. Pardo
- Institute of Plant Biochemistry and Photosynthesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Seville, Spain
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Rubio L, Díaz-García J, Amorim-Silva V, Macho AP, Botella MA, Fernández JA. Molecular Characterization of ZosmaNRT2, the Putative Sodium Dependent High-Affinity Nitrate Transporter of Zostera marina L. Int J Mol Sci 2019; 20:ijms20153650. [PMID: 31357380 PMCID: PMC6695921 DOI: 10.3390/ijms20153650] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 07/19/2019] [Accepted: 07/24/2019] [Indexed: 01/24/2023] Open
Abstract
One of the most important adaptations of seagrasses during sea colonization was the capacity to grow at the low micromolar nitrate concentrations present in the sea. In contrast to terrestrial plants that use H+ symporters for high-affinity NO3− uptake, seagrasses such as Zostera marina L. use a Na+-dependent high-affinity nitrate transporter. Interestingly, in the Z. marina genome, only one gene (Zosma70g00300.1; NRT2.1) is annotated to this function. Analysis of this sequence predicts the presence of 12 transmembrane domains, including the MFS domains of the NNP transporter family and the “nitrate signature” that appears in all members of the NNP family. Phylogenetic analysis shows that this sequence is more related to NRT2.5 than to NRT2.1, sharing a common ancestor with both monocot and dicot plants. Heterologous expression of ZosmaNRT2-GFP together with the high-affinity nitrate transporter accessory protein ZosmaNAR2 (Zosma63g00220.1) in Nicotiana benthamiana leaves displayed four-fold higher fluorescence intensity than single expression of ZosmaNRT2-GFP suggesting the stabilization of NRT2 by NAR2. ZosmaNRT2-GFP signal was present on the Hechtian-strands in the plasmolyzed cells, pointing that ZosmaNRT2 is localized on the plasma membrane and that would be stabilized by ZosmaNAR2. Taken together, these results suggest that Zosma70g00300.1 would encode a high-affinity nitrate transporter located at the plasma membrane, equivalent to NRT2.5 transporters. These molecular data, together with our previous electrophysiological results support that ZosmaNRT2 would have evolved to use Na+ as a driving ion, which might be an essential adaptation of seagrasses to colonize marine environments.
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Affiliation(s)
- Lourdes Rubio
- Department of Botánica y Fisiología Vegetal, Campus de Teatinos, University of Málaga, 29071 Málaga, Spain.
| | - Jordi Díaz-García
- Department of Botánica y Fisiología Vegetal, Campus de Teatinos, University of Málaga, 29071 Málaga, Spain
| | - Vítor Amorim-Silva
- Department Biología Molecular y Bioquímica, Instituto de Hortofruticultura Subtropical y Mediterránea ''La Mayora'' (IHSM-UMA-CSIC), University of Málaga, Campus Teatinos, 29071 Málaga, Spain
| | - Alberto P Macho
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Miguel A Botella
- Department Biología Molecular y Bioquímica, Instituto de Hortofruticultura Subtropical y Mediterránea ''La Mayora'' (IHSM-UMA-CSIC), University of Málaga, Campus Teatinos, 29071 Málaga, Spain
| | - José A Fernández
- Department of Botánica y Fisiología Vegetal, Campus de Teatinos, University of Málaga, 29071 Málaga, Spain
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Capelari M, Johnson KA, Latack B, Roth J, Powers W. The effect of encapsulated nitrate and monensin on ruminal fermentation using a semi-continuous culture system. J Anim Sci 2018; 96:3446-3459. [PMID: 29800454 DOI: 10.1093/jas/sky211] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 05/24/2018] [Indexed: 01/18/2023] Open
Abstract
Because enteric methane (CH4) production from ruminants represents a source of greenhouse gas emissions and an energy loss for the host animal alternatives to minimize emissions is a current research priority. Seven 37-d trials tested the effect of encapsulated nitrate (EN) and sodium monensin (MON) in diets commonly fed to dairy (DAIRY; 50:50 forage to concentrate; four trials) and beef cattle (BEEF; 15:85 forage to concentrate; three trials) on rumen fermentation and CH4 production using a semi-continuous fermentation system. A 3 × 2 factorial arrangement was used and additives (0, 1.25, and 2.5% of EN; 0 and 4 mg/L of MON) were tested alone and combined (EN + MON) totaling six treatments. Rumen fluid was pooled from five nonadapted lactating cows fed 50:50 forage to concentrate diet 3 h after morning feeding, and 1 L of processed inoculum was transferred to 2.2-L vessels. Treatment diets were added to nylon bags which remained in the anaerobic fermentation of mixed rumen microorganisms for 48 h. Nitrate decreased CH4 production in DAIRY (24.7 vs. 32.1 mM/d; P < 0.01) and BEEF trials (33.5 vs. 43.5 mM/d; P < 0.01). Methane production was decreased by MON in DAIRY (26.3 vs. 32.1; P < 0.01) and BEEF (26.6 vs. 43.5 mM/d; P < 0.01). The combination of EN + MON further decreased CH4 in DAIRY (21.3 vs. 32.1 mM/d; P = 0.03) and BEEF (19.3 vs. 43.5 mM/d; P = 0.01). Nitrate did not affect major VFA production in DAIRY and BEEF trials, but significantly decreased digestion of protein (96.8 vs. 97.6%; P < 0.01) and starch (79.0 vs. 80.4%; P < 0.01) in DAIRY and NDF (29.3 vs. 32.5%; P < 0.01) and starch (88.5 vs. 90.3%; P < 0.01) in BEEF. Monensin significantly affected VFA pattern with an increase in propionate (P < 0.01) and a decrease on acetate (P < 0.01) production with consequent decrease on acetate-to-propionate ratio in DAIRY (1.6 vs. 2.0; P < 0.01) and BEEF (1.6 vs. 1.9; P < 0.01). Monensin decreased NDF digestion in BEEF only (29.3 vs. 32.5 %; P < 0.01). Significant concentrations of nitrate and nitrite were detected only for EN and EN + MON (P < 0.01). Nitrate and MON effectively decreased CH4 production when fed separately and the combination of additives additively decreased CH4 production.
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Affiliation(s)
- Matheus Capelari
- Department of Animal Science, Michigan State University, East Lansing, MI
| | - Kristen A Johnson
- Department of Animal Science, Washington State University, Pullman, WA
| | - Brooke Latack
- Department of Animal Science, Michigan State University, East Lansing, MI
| | - Jolene Roth
- Department of Animal Science, Michigan State University, East Lansing, MI
| | - Wendy Powers
- Division of Agriculture and Natural Resources, University of California, Oakland, CA
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Na⁺-Dependent High-Affinity Nitrate, Phosphate and Amino Acids Transport in Leaf Cells of the Seagrass Posidonia oceanica (L.) Delile. Int J Mol Sci 2018; 19:ijms19061570. [PMID: 29795043 PMCID: PMC6032226 DOI: 10.3390/ijms19061570] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 05/21/2018] [Accepted: 05/22/2018] [Indexed: 01/06/2023] Open
Abstract
Posidonia oceanica (L.) Delile is a seagrass, the only group of vascular plants to colonize the marine environment. Seawater is an extreme yet stable environment characterized by high salinity, alkaline pH and low availability of essential nutrients, such as nitrate and phosphate. Classical depletion experiments, membrane potential and cytosolic sodium measurements were used to characterize the high-affinity NO₃-, Pi and amino acids uptake mechanisms in this species. Net uptake rates of both NO₃- and Pi were reduced by more than 70% in the absence of Na⁺. Micromolar concentrations of NO₃- depolarized mesophyll leaf cells plasma membrane. Depolarizations showed saturation kinetics (Km = 8.7 ± 1 μM NO₃-), which were not observed in the absence of Na⁺. NO₃- induced depolarizations at increasing Na⁺ also showed saturation kinetics (Km = 7.2 ± 2 mM Na⁺). Cytosolic Na⁺ measured in P. oceanica leaf cells (17 ± 2 mM Na⁺) increased by 0.4 ± 0.2 mM Na⁺ upon the addition of 100 μM NO₃-. Na⁺-dependence was also observed for high-affinity l-ala and l-cys uptake and high-affinity Pi transport. All together, these results strongly suggest that NO₃-, amino acids and Pi uptake in P. oceanica leaf cells are mediated by high-affinity Na⁺-dependent transport systems. This mechanism seems to be a key step in the process of adaptation of seagrasses to the marine environment.
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11
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Rubio L, García D, García-Sánchez MJ, Niell FX, Felle HH, Fernández JA. Direct uptake of HCO 3- in the marine angiosperm Posidonia oceanica (L.) Delile driven by a plasma membrane H + economy. PLANT, CELL & ENVIRONMENT 2017; 40:2820-2830. [PMID: 28815648 DOI: 10.1111/pce.13057] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 08/08/2017] [Accepted: 08/09/2017] [Indexed: 06/07/2023]
Abstract
Seagrasses access HCO3- for photosynthesis by 2 mechanisms, apoplastic carbonic anhydrase-mediated dehydration of HCO3- to CO2 and direct HCO3- uptake. Here, we have studied plasma membrane energization and the mechanism for HCO3- import in Posidonia oceanica. Classical electrophysiology and ion-selective microelectrodes were used to measure the membrane potential, cytosolic pH, and the cytosolic concentrations of Na+ and Cl- upon the addition of HCO3- . The photosynthetic response to HCO3- and to inhibitors was also measured. Results indicate that the primary pump of P. oceanica plasma membrane is a fusicoccin-sensitive H+ -ATPase. Bicarbonate depolarizes the plasma membrane voltage and transiently acidifies the cytosol, indicating that HCO3- is transported into the cells by an H+ -symport. Initial cytosolic acidification is followed by an alkalinization, suggesting an internal dehydration of HCO3- . The lack of cytosolic Na+ and Cl- responses rules out the contribution of these ions to HCO3- transport. The energetics of nH+ /HCO3- symport allows, for n = 1, an estimate of cytosolic accumulation of 0.22 mM HCO3- . Because this transporter could permit accumulation of HCO3- up to 100 times above the equilibrium concentration, it would be a significant component of a carbon-concentrating mechanism in this species.
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Affiliation(s)
- Lourdes Rubio
- Departamento de Biología Vegetal, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos S/N, Málaga, 29071, Spain
| | - Delia García
- Departamento de Biología Vegetal, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos S/N, Málaga, 29071, Spain
| | - María J García-Sánchez
- Departamento de Biología Vegetal, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos S/N, Málaga, 29071, Spain
| | - F Xavier Niell
- Departamento de Ecología y Geología, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos S/N, Málaga, 29071, Spain
| | - Hubert H Felle
- Departamento de Biología Vegetal, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos S/N, Málaga, 29071, Spain
| | - José A Fernández
- Departamento de Biología Vegetal, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos S/N, Málaga, 29071, Spain
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12
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Álvarez-Aragón R, Rodríguez-Navarro A. Nitrate-dependent shoot sodium accumulation and osmotic functions of sodium in Arabidopsis under saline conditions. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 91:208-219. [PMID: 28370621 DOI: 10.1111/tpj.13556] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 03/24/2017] [Accepted: 03/27/2017] [Indexed: 05/02/2023]
Abstract
Improving crop plants to be productive in saline soils or under irrigation with saline water would be an important technological advance in overcoming the food and freshwater crises that threaten the world population. However, even if the transformation of a glycophyte into a plant that thrives under seawater irrigation was biologically feasible, current knowledge about Na+ effects would be insufficient to support this technical advance. Intriguingly, crucial details about Na+ uptake and its function in the plant have not yet been well established. We here propose that under saline conditions two nitrate-dependent transport systems in series that take up and load Na+ into the xylem constitute the major pathway for the accumulation of Na+ in Arabidopsis shoots; this pathway can also function with chloride at high concentrations. In nrt1.1 nitrate transport mutants, plant Na+ accumulation was partially defective, which suggests that NRT1.1 either partially mediates or modulates the nitrate-dependent Na+ transport. Arabidopsis plants exposed to an osmotic potential of -1.0 MPa (400 mOsm) for 24 h showed high water loss and wilting in sorbitol or Na/MES, where Na+ could not be accumulated. In contrast, in NaCl the plants that accumulated Na+ lost a low amount of water, and only suffered transitory wilting. We discuss that in Arabidopsis plants exposed to high NaCl concentrations, root Na+ uptake and tissue accumulation fulfil the primary function of osmotic adjustment, even if these processes lead to long-term toxicity.
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Affiliation(s)
- Rocío Álvarez-Aragón
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Campus de Montegancedo, 28223, Pozuelo de Alarcón, Madrid, Spain
| | - Alonso Rodríguez-Navarro
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Campus de Montegancedo, 28223, Pozuelo de Alarcón, Madrid, Spain
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Larkum AWD, Davey PA, Kuo J, Ralph PJ, Raven JA. Carbon-concentrating mechanisms in seagrasses. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3773-3784. [PMID: 28911056 DOI: 10.1093/jxb/erx206] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Seagrasses are unique angiosperms that carry out growth and reproduction submerged in seawater. They occur in at least three families of the Alismatales. All have chloroplasts mainly in the cells of the epidermis. Living in seawater, the supply of inorganic carbon (Ci) to the chloroplasts is diffusion limited, especially under unstirred conditions. Therefore, the supply of CO2 and bicarbonate across the diffusive boundary layer on the outer side of the epidermis is often a limiting factor. Here we discuss the evidence for mechanisms that enhance the uptake of Ci into the epidermal cells. Since bicarbonate is plentiful in seawater, a bicarbonate pump might be expected; however, the evidence for such a pump is not strongly supported. There is evidence for a carbonic anhydrase outside the outer plasmalemma. This, together with evidence for an outward proton pump, suggests the possibility that local acidification leads to enhanced concentrations of CO2 adjacent to the outer tangential epidermal walls, which enhances the uptake of CO2, and this could be followed by a carbon-concentrating mechanism (CCM) in the cytoplasm and/or chloroplasts. The lines of evidence for such an epidermal CCM are discussed, including evidence for special 'transfer cells' in some but not all seagrass leaves in the tangential inner walls of the epidermal cells. It is concluded that seagrasses have a CCM but that the case for concentration of CO2 at the site of Rubisco carboxylation is not proven.
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Affiliation(s)
- Anthony William D Larkum
- Plant Functional Biology and Global Climate Change Cluster, University of Technology Sydney, NSW 2009, Australia
| | - Peter A Davey
- Plant Functional Biology and Global Climate Change Cluster, University of Technology Sydney, NSW 2009, Australia
| | - John Kuo
- Electron Microscope Centre, University of Western Australia, WA 6900, Australia
| | - Peter J Ralph
- Plant Functional Biology and Global Climate Change Cluster, University of Technology Sydney, NSW 2009, Australia
| | - John A Raven
- Plant Functional Biology and Global Climate Change Cluster, University of Technology Sydney, NSW 2009, Australia
- University of Dundee at JHI, Invergowrie, Dundee, UK
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14
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Fernández PA, Roleda MY, Leal PP, Hurd CL. Seawater pH, and not inorganic nitrogen source, affects pH at the blade surface of Macrocystis pyrifera: implications for responses of the giant kelp to future oceanic conditions. PHYSIOLOGIA PLANTARUM 2017; 159:107-119. [PMID: 27293117 DOI: 10.1111/ppl.12478] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 05/16/2016] [Accepted: 05/23/2016] [Indexed: 06/06/2023]
Abstract
Ocean acidification (OA), the ongoing decline in seawater pH, is predicted to have wide-ranging effects on marine organisms and ecosystems. For seaweeds, the pH at the thallus surface, within the diffusion boundary layer (DBL), is one of the factors controlling their response to OA. Surface pH is controlled by both the pH of the bulk seawater and by the seaweeds' metabolism: photosynthesis and respiration increase and decrease pH within the DBL (pHDBL ), respectively. However, other metabolic processes, especially the uptake of inorganic nitrogen (Ni ; NO3- and NH4+ ) may also affect the pHDBL . Using Macrocystis pyrifera, we hypothesized that (1) NO3- uptake will increase the pHDBL , whereas NH4+ uptake will decrease it, (2) if NO3- is cotransported with H+ , increases in pHDBL would be greater under an OA treatment (pH = 7.65) than under an ambient treatment (pH = 8.00), and (3) decreases in pHDBL will be smaller at pH 7.65 than at pH 8.00, as higher external [H+ ] might affect the strength of the diffusion gradient. Overall, Ni source did not affect the pHDBL . However, increases in pHDBL were greater at pH 7.65 than at pH 8.00. CO2 uptake was higher at pH 7.65 than at pH 8.00, whereas HCO3- uptake was unaffected by pH. Photosynthesis and respiration control pHDBL rather than Ni uptake. We suggest that under future OA, Macrocystis pyrifera will metabolically modify its surface microenvironment such that the physiological processes of photosynthesis and Ni uptake will not be affected by a reduced pH.
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Affiliation(s)
| | - Michael Y Roleda
- Department of Botany, University of Otago, Dunedin, 9054, New Zealand
| | - Pablo P Leal
- Department of Botany, University of Otago, Dunedin, 9054, New Zealand
| | - Catriona L Hurd
- Department of Botany, University of Otago, Dunedin, 9054, New Zealand
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Lv S, Jiang P, Nie L, Chen X, Tai F, Wang D, Fan P, Feng J, Bao H, Wang J, Li Y. H(+) -pyrophosphatase from Salicornia europaea confers tolerance to simultaneously occurring salt stress and nitrogen deficiency in Arabidopsis and wheat. PLANT, CELL & ENVIRONMENT 2015; 38:2433-49. [PMID: 25920512 DOI: 10.1111/pce.12557] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 04/20/2015] [Indexed: 05/14/2023]
Abstract
High salinity and nitrogen (N) deficiency in soil are two key factors limiting crop productivity, and they usually occur simultaneously. Here we firstly found that H(+) -PPase is involved in salt-stimulated NO3 (-) uptake in the euhalophyte Salicornia europaea. Then, two genes (named SeVP1 and SeVP2) encoding H(+) -PPase from S. europaea were characterized. The expression of SeVP1 and SeVP2 was induced by salt stress and N starvation. Both SeVP1 or SeVP2 transgenic Arabidopsis and wheat plants outperformed the wild types (WTs) when high salt and low N occur simultaneously. The transgenic Arabidopsis plants maintained higher K(+) /Na(+) ratio in leaves and exhibited increased NO3 (-) uptake, inorganic pyrophosphate-dependent vacuolar nitrate efflux and assimilation capacity under this double stresses. Furthermore, they had more soluble sugars in shoots and roots and less starch accumulation in shoots than WT. These performances can be explained by the up-regulated expression of ion, nitrate and sugar transporter genes in transgenic plants. Taken together, our results suggest that up-regulation of H(+) -PPase favours the transport of photosynthates to root, which could promote root growth and integrate N and carbon metabolism in plant. This work provides potential strategies for improving crop yields challenged by increasing soil salinization and shrinking farmland.
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Affiliation(s)
- Sulian Lv
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Ping Jiang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Lingling Nie
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Xianyang Chen
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Fang Tai
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Duoliya Wang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Pengxiang Fan
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Juanjuan Feng
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Hexigeduleng Bao
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Jinhui Wang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Yinxin Li
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
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16
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Feng J, Wang J, Fan P, Jia W, Nie L, Jiang P, Chen X, Lv S, Wan L, Chang S, Li S, Li Y. High-throughput deep sequencing reveals that microRNAs play important roles in salt tolerance of euhalophyte Salicornia europaea. BMC PLANT BIOLOGY 2015; 15:63. [PMID: 25848810 PMCID: PMC4349674 DOI: 10.1186/s12870-015-0451-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 02/06/2015] [Indexed: 05/07/2023]
Abstract
BACKGROUND microRNAs (miRNAs) are implicated in plant development processes and play pivotal roles in plant adaptation to environmental stresses. Salicornia europaea, a salt mash euhalophyte, is a suitable model plant to study salt adaptation mechanisms. S. europaea is also a vegetable, forage, and oilseed that can be used for saline land reclamation and biofuel precursor production on marginal lands. Despite its importance, no miRNA has been identified from S. europaea thus far. RESULTS Deep sequencing was performed to investigate small RNA transcriptome of S. europaea. Two hundred and ten conserved miRNAs comprising 51 families and 31 novel miRNAs (including seven miRNA star sequences) belonging to 30 families were identified. About half (13 out of 31) of the novel miRNAs were only detected in salt-treated samples. The expression of 43 conserved and 13 novel miRNAs significantly changed in response to salinity. In addition, 53 conserved and 13 novel miRNAs were differentially expressed between the shoots and roots. Furthermore, 306 and 195 S. europaea unigenes were predicted to be targets of 41 conserved and 29 novel miRNA families, respectively. These targets encoded a wide range of proteins, and genes involved in transcription regulation constituted the largest category. Four of these genes encoding laccase, F-box family protein, SAC3/GANP family protein, and NADPH cytochrome P-450 reductase were validated using 5'-RACE. CONCLUSIONS Our results indicate that specific miRNAs are tightly regulated by salinity in the shoots and/or roots of S. europaea, which may play important roles in salt tolerance of this euhalophyte. The S. europaea salt-responsive miRNAs and miRNAs that target transcription factors, nucleotide binding site-leucine-rich repeat proteins and enzymes involved in lignin biosynthesis as well as carbon and nitrogen metabolism may be applied in genetic engineering of crops with high stress tolerance, and genetic modification of biofuel crops with high biomass and regulatable lignin biosynthesis.
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Affiliation(s)
- Juanjuan Feng
- />Institute of Botany, Key Laboratory of Plant Molecular Physiology, Chinese Academy of Sciences, Beijing, 100093 China
| | - Jinhui Wang
- />Institute of Botany, Key Laboratory of Plant Molecular Physiology, Chinese Academy of Sciences, Beijing, 100093 China
| | - Pengxiang Fan
- />Institute of Botany, Key Laboratory of Plant Molecular Physiology, Chinese Academy of Sciences, Beijing, 100093 China
- />Department of Biochemistry and Molecular Biology, Michigan State University, 603 Wilson road, East Lansing, MI 48824 USA
| | - Weitao Jia
- />Institute of Botany, Key Laboratory of Plant Molecular Physiology, Chinese Academy of Sciences, Beijing, 100093 China
| | - Lingling Nie
- />Institute of Botany, Key Laboratory of Plant Molecular Physiology, Chinese Academy of Sciences, Beijing, 100093 China
| | - Ping Jiang
- />Institute of Botany, Key Laboratory of Plant Molecular Physiology, Chinese Academy of Sciences, Beijing, 100093 China
| | - Xianyang Chen
- />Institute of Botany, Key Laboratory of Plant Molecular Physiology, Chinese Academy of Sciences, Beijing, 100093 China
| | - Sulian Lv
- />Institute of Botany, Key Laboratory of Plant Molecular Physiology, Chinese Academy of Sciences, Beijing, 100093 China
| | - Lichuan Wan
- />Institute of Botany, Key Laboratory of Plant Molecular Physiology, Chinese Academy of Sciences, Beijing, 100093 China
| | - Sandra Chang
- />Beijing Engineering Research Center for Biofuels, Tsinghua University, Beijing, 100084 China
- />Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, 100084 China
| | - Shizhong Li
- />Beijing Engineering Research Center for Biofuels, Tsinghua University, Beijing, 100084 China
- />Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, 100084 China
| | - Yinxin Li
- />Institute of Botany, Key Laboratory of Plant Molecular Physiology, Chinese Academy of Sciences, Beijing, 100093 China
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Adams E, Shin R. Transport, signaling, and homeostasis of potassium and sodium in plants. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2014; 56:231-49. [PMID: 24393374 DOI: 10.1111/jipb.12159] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 12/31/2013] [Indexed: 05/17/2023]
Abstract
Potassium (K⁺) is an essential macronutrient in plants and a lack of K⁺ significantly reduces the potential for plant growth and development. By contrast, sodium (Na⁺), while beneficial to some extent, at high concentrations it disturbs and inhibits various physiological processes and plant growth. Due to their chemical similarities, some functions of K⁺ can be undertaken by Na⁺ but K⁺ homeostasis is severely affected by salt stress, on the other hand. Recent advances have highlighted the fascinating regulatory mechanisms of K⁺ and Na⁺ transport and signaling in plants. This review summarizes three major topics: (i) the transport mechanisms of K⁺ and Na⁺ from the soil to the shoot and to the cellular compartments; (ii) the mechanisms through which plants sense and respond to K⁺ and Na⁺ availability; and (iii) the components involved in maintenance of K⁺/Na⁺ homeostasis in plants under salt stress.
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Affiliation(s)
- Eri Adams
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan
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Alexandre A, Silva J, Buapet P, Björk M, Santos R. Effects of CO(2) enrichment on photosynthesis, growth, and nitrogen metabolism of the seagrass Zostera noltii. Ecol Evol 2012; 2:2625-35. [PMID: 23145346 PMCID: PMC3492787 DOI: 10.1002/ece3.333] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 06/19/2012] [Accepted: 06/22/2012] [Indexed: 11/21/2022] Open
Abstract
Seagrass ecosystems are expected to benefit from the global increase in CO(2) in the ocean because the photosynthetic rate of these plants may be C(i)-limited at the current CO(2) level. As well, it is expected that lower external pH will facilitate the nitrate uptake of seagrasses if nitrate is cotransported with H(+) across the membrane as in terrestrial plants. Here, we investigate the effects of CO(2) enrichment on both carbon and nitrogen metabolism of the seagrass Zostera noltii in a mesocosm experiment where plants were exposed for 5 months to two experimental CO(2) concentrations (360 and 700 ppm). Both the maximum photosynthetic rate (P(m)) and photosynthetic efficiency (α) were higher (1.3- and 4.1-fold, respectively) in plants exposed to CO(2)-enriched conditions. On the other hand, no significant effects of CO(2) enrichment on leaf growth rates were observed, probably due to nitrogen limitation as revealed by the low nitrogen content of leaves. The leaf ammonium uptake rate and glutamine synthetase activity were not significantly affected by increased CO(2) concentrations. On the other hand, the leaf nitrate uptake rate of plants exposed to CO(2)-enriched conditions was fourfold lower than the uptake of plants exposed to current CO(2) level, suggesting that in the seagrass Z. noltii nitrate is not cotransported with H(+) as in terrestrial plants. In contrast, the activity of nitrate reductase was threefold higher in plant leaves grown at high-CO(2) concentrations. Our results suggest that the global effects of CO(2) on seagrass production may be spatially heterogeneous and depend on the specific nitrogen availability of each system. Under a CO(2) increase scenario, the natural levels of nutrients will probably become limiting for Z. noltii. This potential limitation becomes more relevant because the expected positive effect of CO(2) increase on nitrate uptake rate was not confirmed.
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Affiliation(s)
- Ana Alexandre
- Marine Plant Ecology Research Group, CCMAR – Centre of Marine Sciences, Universidade do AlgarveFaro, Portugal
| | - João Silva
- Marine Plant Ecology Research Group, CCMAR – Centre of Marine Sciences, Universidade do AlgarveFaro, Portugal
| | | | - Mats Björk
- Botany Department, Stockholm UniversityStockholm, Sweden
| | - Rui Santos
- Marine Plant Ecology Research Group, CCMAR – Centre of Marine Sciences, Universidade do AlgarveFaro, Portugal
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Raven JA, Hurd CL. Ecophysiology of photosynthesis in macroalgae. PHOTOSYNTHESIS RESEARCH 2012; 113:105-25. [PMID: 22843100 DOI: 10.1007/s11120-012-9768-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 07/04/2012] [Indexed: 05/07/2023]
Abstract
Macroalgae occur in the marine benthos from the upper intertidal to depths of more than 200 m, contributing up to 1 Pg C per year to global primary productivity. Freshwater macroalgae are mainly green (Chlorophyta) with some red (Rhodophyta) and a small contribution of brown (Phaeophyceae) algae, while in the ocean all three higher taxa are important. Attempts to relate the depth distribution of three higher taxa of marine macroalgae to their photosynthetic light use through their pigmentation in relation to variations in spectral quality of photosynthetically active radiation (PAR) with depth (complementary chromatic adaptation) and optical thickness (package effect) have been relatively unsuccessful. The presence (Chlorophyta, Phaeophyceae) or absence (Rhodophyta) of a xanthophyll cycle is also not well correlated with depth distribution of marine algae. The relative absence of freshwater brown algae does not seem to be related to their photosynthetic light use. Photosynthetic inorganic carbon acquisition in some red and a few green macroalgae involves entry of CO(2) by diffusion. Other red and green macroalgae, and brown macroalgae, have CO(2) concentrating mechanisms; these frequently involve acid and alkaline zones on the surface of the alga with CO(2) (produced from HCO(3) (-)) entering in the acid zones, while some macroalgae have CCMs based on active influx of HCO(3) (-). These various mechanisms of carbon acquisition have different responses to the thickness of the diffusion boundary layer, which is determined by macroalgal morphology and water velocity. Energetic predictions that macroalgae growing at or near the lower limit of PAR for growth should rely on diffusive CO(2) entry without acid and alkaline zones, and on NH(4) (+) rather than NO(3) (-) as nitrogen source, are only partially borne out by observation. The impact of global environmental change on marine macroalgae mainly relates to ocean acidification and warming with shoaling of the thermocline and decreased nutrient flux to the upper mixed layer. Predictions of the impact on macroalgae requires further experiments on interactions among increased inorganic carbon, increased temperature and decreased nitrogen and phosphorus supply, and, when possible, studies of genetic adaptation to environmental change.
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Affiliation(s)
- John A Raven
- Division of Plant Sciences, University of Dundee at the James Hutton Institute, Invergowrie, Dundee, DD2 5DA, Scotland, UK.
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Tammam AA, Mostafa EM. Identification of mRNA transcript and screening of amino acids in response to interaction of salinity and nitrate in aquatic fern Azolla caroliniana. ACTA BIOLOGICA HUNGARICA 2012; 63:250-67. [PMID: 22695523 DOI: 10.1556/abiol.63.2012.2.7] [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: 11/19/2022]
Abstract
The mechanisms by which Azolla caroliniana respond to salt stress in absence and presence of nitrate is investigated. Screening of amino acid and differential display is used to compare overall differences in gene expression between salinity-stressed and unstressed Azolla caroliniana by quantitative reverse transcriptase polymerase chain reaction (RT-PC R). Results showed that under saline conditions, aspartic acid, glutamic acid, alanine and leucine were the amino acids found to be abundant in Azolla caroliniana, accounting for 11.26%, 8.66%, 9.43%, and 12.36%, respectively. Following salinity stress, a decrease in free glutamate concomitant with a parallel decrease in free proline was indeed evident. Interaction between nitrate and salinity stress increased proline content significantly. By screening a cDNA library, we have identified protein products by homology with known proteins. The RNA transcripts encoding protein influencing secondary metabolites and vacuolar Na+/H+ antiporter that facilitate the transport system. The databasematched under interaction of nitrate and 50 mM NaCl were associated with wall biosynthesis, disease resistance, metabolite transport and protein regulator, other gene for metabolism of steroids and secondary transport. Results obtained from this research could represent a key step in understanding the molecular mechanism of salt tolerance of Azolla caroliniana in the presence and absence of nitrate.
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Affiliation(s)
- A A Tammam
- Department of Botany and Microbiology, Faculty of Science, Alexandria University, 21511 Alexandria, Egypt.
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Pilon-Smits EAH, Quinn CF, Tapken W, Malagoli M, Schiavon M. Physiological functions of beneficial elements. CURRENT OPINION IN PLANT BIOLOGY 2009; 12:267-74. [PMID: 19477676 DOI: 10.1016/j.pbi.2009.04.009] [Citation(s) in RCA: 272] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Revised: 04/01/2009] [Accepted: 04/22/2009] [Indexed: 05/02/2023]
Abstract
Aluminum (Al), cobalt (Co), sodium (Na), selenium (Se), and silicon (Si) are considered beneficial elements for plants: they are not required by all plants but can promote plant growth and may be essential for particular taxa. These beneficial elements have been reported to enhance resistance to biotic stresses such as pathogens and herbivory, and to abiotic stresses such as drought, salinity, and nutrient toxicity or deficiency. The beneficial effects of low doses of Al, Co, Na and Se have received little attention compared to toxic effects that typically occur at higher concentrations. Better understanding of the effects of beneficial elements is important to improve crop productivity and enhance plant nutritional value for a growing world population.
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Singh SS, Singh SK, Mishra AK. Na(+) regulation by combined nitrogen in Azolla pinnata-Anabaena azollae symbiotic association during salt toxicity. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2008; 69:32-8. [PMID: 17521724 DOI: 10.1016/j.ecoenv.2007.04.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 04/05/2007] [Accepted: 04/08/2007] [Indexed: 05/15/2023]
Abstract
To study the regulation of Na(+) ion by combined-N sources in Azolla pinnata-Anabaena azollae, Na(+) influx, intracellular Na(+) and Na(+) efflux were investigated in the presence of different N-sources (N(2), NH(4)(+), NO(3)(-) and urea) and various NaCl concentrations. Sodium influx by Azolla pinnata fronds was minimum in the presence of NO(3)(-). Almost identical levels of intracellular sodium, although less than N(2) and NH(4)(+) incubated fronds were observed in the presence of NO(3)(-) and urea. Efflux of sodium was minimum in urea and NO(3)(-) grown fronds. A low residual sodium was observed in the fronds incubated in NO(3)(-) and urea supplemented media. Results suggest that nitrate and urea curtailed the entry of sodium, reduced salt toxicity maximally by maintaining the minimum level of sodium and also conserved energy due to slow influx and efflux of Na(+) within the fronds during salt shock and the process of adaptation.
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Affiliation(s)
- Satya S Singh
- Department of Botany, Banaras Hindu University, Varanasi 221005, India.
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23
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Giordano M, Norici A, Gilmour DJ, Raven JA. Physiological responses of the green alga Dunaliella parva (Volvocales, Chlorophyta) to controlled incremental changes in the N source. FUNCTIONAL PLANT BIOLOGY : FPB 2007; 34:925-934. [PMID: 32689421 DOI: 10.1071/fp07049] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2007] [Accepted: 07/20/2007] [Indexed: 06/11/2023]
Abstract
This work is aimed at obtaining information on the acclimation processes of the green flagellate Dunaliella parva Lerche to gradual changes in the N source from NO3- to NH4+, in continuous cultures. Photosynthesis, dark respiration, and light-independent carbon fixation (LICF) rates, chlorophyll a fluorescence, RUBISCO and phosphoenolpyruvate carboxylase (PEPc) activities, plasmalemma electrical potential difference, cell volume, and absolute or relative amounts of major cell constituents were measured. Two phases characterised the response to the transition from NO3- to NH4+: (1) an initial phase in which photosynthesis and anaplerosis were stimulated and protein increased; (2) a subsequent phase in which most parameters reached new values that were close to those at the beginning of the experiment (100% NO3-). The only exceptions were PEPc activity and LICF, whose rates remained at least 2-fold higher than at 100% NO3-, when NH4+ was the sole N source. The results are indicative of a tendency to re-establish homeostasis, after an initial perturbation of the intracellular composition. The roles of different metabolic processes during acclimation are discussed.
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Affiliation(s)
- Mario Giordano
- Laboratorio di Fisiologia delle Alghe, Dipartimento di Scienze del Mare, Università Politecnica delle Marche, via Brecce Bianche, 60131 Ancona, Italy
| | - Alessandra Norici
- Laboratorio di Fisiologia delle Alghe, Dipartimento di Scienze del Mare, Università Politecnica delle Marche, via Brecce Bianche, 60131 Ancona, Italy
| | - Daniel J Gilmour
- Department of Molecular Biology and Biotechnology, University of Sheffield, S10 2TN Sheffield, UK
| | - John A Raven
- Scottish Crop Research Institute, University of Dundee at SCRI, Invergowrie, DD2 5DA Dundee, UK
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Song J, Ding X, Feng G, Zhang F. Nutritional and osmotic roles of nitrate in a euhalophyte and a xerophyte in saline conditions. THE NEW PHYTOLOGIST 2006; 171:357-66. [PMID: 16866942 DOI: 10.1111/j.1469-8137.2006.01748.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The effects of salinity and nitrogen (N) on growth and the role of NO3- in osmotic adjustment in the leaf-succulent euhalophyte Suaeda physophora and the stem-succulent xerophyte Haloxylon persicum were evaluated. Seedlings were exposed to 1 or 300 mm NaCl in 0.05, 1 or 10 mm NO3- -N treatments for 24 d. At 10 mm NO3-, 300 mm NaCl had no adverse effect on the concentration of NO3-, the content of organic N, and the estimated contribution of NO3- to osmotic potential in leaves of S. physophora, but markedly reduced these in stems of H. persicum. At 300 mm NaCl, more NO3- but less Cl- and Na+ were involved in osmotic adjustment in leaves of S. physophora compared with that in stems of H. persicum. The contribution of NO3- to osmotic potential was much higher in S. physophora, but lower in H. persicum, than that of amino acids at 300 mm NaCl. The nutritional and osmotic roles of NO3- -N seem to be more important in the euhalophyte S. physophora than in the xerophyte H. persicum under saline conditions. These characteristics may determine the natural distributions of the two species in saline or arid environments.
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Affiliation(s)
- Jie Song
- College of Resource and Environmental Science, China Agricultural University, Beijing 100094 China
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Incharoensakdi A, Laloknam S. Nitrate uptake in the halotolerant cyanobacterium Aphanothece halophytica is energy-dependent driven by DeltapH. BMB Rep 2005; 38:468-73. [PMID: 16053714 DOI: 10.5483/bmbrep.2005.38.4.468] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The energetics of nitrate uptake by intact cells of the halotolerant cyanobacterium Aphanothece halophytica were investigated. Nitrate uptake was inhibited by various protonophores suggesting the coupling of nitrate uptake to the proton motive force. An artificially-generated pH gradient across the membrane (DeltapH) caused an increase of nitrate uptake. In contrast, the suppression of DeltapH resulted in a decrease of nitrate uptake. The increase of external pH also resulted in an enhancement of nitrate uptake. The generation of the electrical potential across the membrane (Deltapsi) resulted in no elevation of the rate of nitrate uptake. On the other hand, the valinomycin-mediated dissipation of Deltapsi caused no depression of the rate of nitrate uptake. Thus, it is unlikely that Deltapsi participated in the energization of the uptake of nitrate. However, Na(+)-gradient across the membrane was suggested to play a role in nitrate uptake since monensin which collapses Na(+)-gradient strongly inhibited nitrate uptake. Exogenously added glucose and lactate stimulated nitrate uptake in the starved cells. N, N'-dicyclohexylcarbodiimide, an inhibitor of ATPase, could alsoinhibit nitrate uptake suggesting that ATP hydrolysis was required for nitrate uptake. All these results indicate that nitrate uptake in A. halophytica is ATP-dependent, driven by DeltapH and Na(+)-gradient.
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Affiliation(s)
- Aran Incharoensakdi
- Department of Biochemistry and Program of Biotechnology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
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