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Muthui SW, Wei L, Ochieng WA, Linda EL, Otieno DO, Nyongesa EW, Liu F, Xian L. The distinctive level of interaction between carbon and nitrogen metabolisms in the leaves of submerged macrophytes plays a key role in ammonium detoxification. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2024; 268:106840. [PMID: 38278063 DOI: 10.1016/j.aquatox.2024.106840] [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: 10/19/2023] [Revised: 01/08/2024] [Accepted: 01/12/2024] [Indexed: 01/28/2024]
Abstract
Possible ammonium detoxification mechanisms have been proposed recently, on submerged macrophytes, evidently illustrating that glutamate dehydrogenase (GDH) plays a greater role in ammonium detoxification compared to the primary glutamine synthetase/glutamate oxaloacetate transaminase (GS/GOGAT) pathway. In the current investigation, we cultured three submerged macrophytes to extreme concentrations of [NH4+-N] of up to 50 mg/L with the aim of clarifying the interaction between carbon and nitrogen metabolisms. The activities of carboxylation enzymes pyruvate orthophosphate dikinase (PPDK) and phosphoenolpyruvate carboxylase (PEPC), in lieu of Rubisco, increased almost two-fold for ammonium tolerant species P. maackianus and M. spicatum, compared with the sensitive species P. lucens. While these enzymes are well known for their central role in CO2 fixation, their inference in conferring resistance to ammonium stress has not been well elucidated before. In this study, we demonstrate that the overproduction of PEPC and PPDK led to improved photosynthesis, better ammonium assimilation and overall ammonium detoxification in M. spicatum and P. maackianus. These findings propose likelihood for the existence of a complementary ammonium detoxification pathway that targets carbon metabolism, thus, presenting a relatively efficient linkage between nitrogen and carbon metabolisms and identify candidate species for practical restoration of fresh water resources.
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Affiliation(s)
- Samuel Wamburu Muthui
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China; University of Chinese Academy of Sciences, Beijing, China; Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, China
| | - Li Wei
- Changjiang Water Resources and Hydropower Development Group (Hubei) Co., Ltd., Wuhan 430010, China
| | - Wyckliffe Ayoma Ochieng
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China; University of Chinese Academy of Sciences, Beijing, China; Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, China
| | - Elive Limunga Linda
- Hubei University, School of Resources and Environmental Science, Wuhan 430074, China
| | - Duncan Ochieng Otieno
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China; University of Chinese Academy of Sciences, Beijing, China; Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, China
| | - Emmanuel Waswa Nyongesa
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China; University of Chinese Academy of Sciences, Beijing, China; Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, China
| | - Fan Liu
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
| | - Ling Xian
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China.
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Ochieng WA, Wei L, Wagutu GK, Xian L, Muthui SW, Ogada S, Otieno DO, Linda EL, Liu F. Transcriptome Analysis of Macrophytes' Myriophyllum spicatum Response to Ammonium Nitrogen Stress Using the Whole Plant Individual. PLANTS (BASEL, SWITZERLAND) 2023; 12:3875. [PMID: 38005772 PMCID: PMC10675724 DOI: 10.3390/plants12223875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 11/11/2023] [Accepted: 11/13/2023] [Indexed: 11/26/2023]
Abstract
Ammonium toxicity in macrophytes reduces growth and development due to a disrupted metabolism and high carbon requirements for internal ammonium detoxification. To provide more molecular support for ammonium detoxification in the above-ground and below-ground parts of Myriophyllum spicatum, we separated (using hermetic bags) the aqueous medium surrounding the below-ground from that surrounding the above-ground and explored the genes in these two regions. The results showed an upregulation of asparagine synthetase genes under high ammonium concentrations. Furthermore, the transcriptional down and/or upregulation of other genes involved in nitrogen metabolism, including glutamate dehydrogenase, ammonium transporter, and aspartate aminotransferase in above-ground and below-ground parts were crucial for ammonium homeostasis under high ammonium concentrations. The results suggest that, apart from the primary pathway and alternative pathway, the asparagine metabolic pathway plays a crucial role in ammonium detoxification in macrophytes. Therefore, the complex genetic regulatory network in M. spicatum contributes to its ammonium tolerance, and the above-ground part is the most important in ammonium detoxification. Nevertheless, there is a need to incorporate an open-field experimental setup for a conclusive picture of nitrogen dynamics, toxicity, and the molecular response of M. spicatum in the natural environment.
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Affiliation(s)
- Wyckliffe Ayoma Ochieng
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; (W.A.O.); (G.K.W.); (L.X.); (S.W.M.); (D.O.O.)
- Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan 430074, China
- University of the Chinese Academy of Sciences, Beijing 101408, China
| | - Li Wei
- Changjiang Water Resources and Hydropower Development Group (Hubei) Co., Ltd., Wuhan 430010, China;
| | - Godfrey Kinyori Wagutu
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; (W.A.O.); (G.K.W.); (L.X.); (S.W.M.); (D.O.O.)
- Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan 430074, China
- University of the Chinese Academy of Sciences, Beijing 101408, China
| | - Ling Xian
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; (W.A.O.); (G.K.W.); (L.X.); (S.W.M.); (D.O.O.)
| | - Samuel Wamburu Muthui
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; (W.A.O.); (G.K.W.); (L.X.); (S.W.M.); (D.O.O.)
- Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan 430074, China
- University of the Chinese Academy of Sciences, Beijing 101408, China
| | - Stephen Ogada
- Institute for Biotechnology Research, Jomo Kenyatta University of Agriculture and Technology, Nairobi 00200, Kenya;
| | - Duncan Ochieng Otieno
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; (W.A.O.); (G.K.W.); (L.X.); (S.W.M.); (D.O.O.)
- Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan 430074, China
- University of the Chinese Academy of Sciences, Beijing 101408, China
| | - Elive Limunga Linda
- School of Resources and Environmental Science, Hubei University, Wuhan 430062, China;
| | - Fan Liu
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; (W.A.O.); (G.K.W.); (L.X.); (S.W.M.); (D.O.O.)
- Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan 430074, China
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3
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Yuan G, Tan X, Guo P, Xing K, Chen Z, Li D, Yu S, Peng H, Li W, Fu H, Jeppesen E. Linking trait network to growth performance of submerged macrophytes in response to ammonium pulse. WATER RESEARCH 2023; 229:119403. [PMID: 36446174 DOI: 10.1016/j.watres.2022.119403] [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: 08/16/2022] [Revised: 10/17/2022] [Accepted: 11/20/2022] [Indexed: 06/16/2023]
Abstract
Extreme precipitation events caused by climate change leads to large variation of nitrogen input to aquatic ecosystems. Our previous study demonstrated the significant effect of different ammonium pulse patterns (differing in magnitude and frequency) on submersed macrophyte growth based on six plant morphological traits. However, how connectivity among plant traits responds to nitrogen pulse changes, which in turn affects plant performance, has not yet been fully elucidated. The response of three common submersed macrophytes (Myriophyllum spicatum, Vallisneria natans and Potamogeton maackianus) to three ammonium pulse patterns was tested using plant trait network (PTN) analysis based on 18 measured physiological and morphological traits. We found that ammonium pulses enhanced trait connectivity in PTN, which may enable plants to assimilate ammonium and/or mitigate ammonium toxicity. Large input pulses with low frequency had stronger effects on PTNs compared to low input pulses with high frequency. Due to the cumulative and time-lagged effect of the plant response to the ammonium pulse, there was a profound and prolonged effect on plant performance after the release of the pulse. The highly connected traits in PTN were those related to biomass allocation (e.g., plant biomass, stem ratio, leaf ratio and ramet number) rather than physiological traits, while phenotype-related traits (e.g., plant height, root length and AB ratio) and energy storage-related traits (e.g., stem starch) were least connected. V. natans showed clear functional divergence among traits, making it more flexible to cope with unfavorable habitats (i.e., high input pulses with low frequencies). M. spicatum with high RGR revealed strong correlations among traits and thus supported nitrogen accumulation from favourable environments (i.e., low input pulses with high frequencies). Our study highlights the responses of PTN for submerged macrophytes to ammonium pulses depends on their intrinsic metabolic rates, the magnitude, frequency and duration of the pulses, and our results contribute to the understanding of the impact of resource pulses on the population dynamics of submersed macrophytes within the context of global climate change.
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Affiliation(s)
- Guixiang Yuan
- Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, Ecology Department, College of Resources and Environment, Hunan Agricultural University, Changsha, China.
| | - Xiaoyao Tan
- Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, Ecology Department, College of Resources and Environment, Hunan Agricultural University, Changsha, China
| | - Peiqin Guo
- Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, Ecology Department, College of Resources and Environment, Hunan Agricultural University, Changsha, China
| | - Ke Xing
- Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, Ecology Department, College of Resources and Environment, Hunan Agricultural University, Changsha, China
| | - Zhenglong Chen
- Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, Ecology Department, College of Resources and Environment, Hunan Agricultural University, Changsha, China
| | - Dongbo Li
- Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, Ecology Department, College of Resources and Environment, Hunan Agricultural University, Changsha, China
| | - Sizhe Yu
- Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, Ecology Department, College of Resources and Environment, Hunan Agricultural University, Changsha, China
| | - Hui Peng
- Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, Ecology Department, College of Resources and Environment, Hunan Agricultural University, Changsha, China
| | - Wei Li
- Research Institute of Ecology & Environmental Sciences, Nanchang Institute of Technology, Nanchang, 330099, China.
| | - Hui Fu
- Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, Ecology Department, College of Resources and Environment, Hunan Agricultural University, Changsha, China
| | - Erik Jeppesen
- Lake section, Department of Ecoscience, Aarhus University, Aarhus, Denmark; Sino-Danish Centre for Education and Research, Beijing, 100049, China; Limnology Laboratory, Department of Biological Sciences and Centre for Ecosystem Research and Implementation, Middle East Technical University, Ankara, Turkey; Institute of Marine Sciences, Middle East Technical University, Mersin, Turkey
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Zhang Y, Li B, Luo P, Xian Y, Xiao R, Wu J. Glutamine synthetase plays an important role in ammonium tolerance of Myriophyllum aquaticum. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 848:157596. [PMID: 35905951 DOI: 10.1016/j.scitotenv.2022.157596] [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: 12/06/2021] [Revised: 06/30/2022] [Accepted: 07/19/2022] [Indexed: 06/15/2023]
Abstract
High-strength ammonium (NH4+), the main characteristic of swine wastewater, poses a significant threat to the rural ecological environment. As a novel phytoremediation technology, Myriophyllum aquaticum wetlands have high tolerance and removal rate of NH4+. Glutamine synthetase (GS), a pivotal enzyme in nitrogen (N) metabolism, is hypothesized to play an important role in the tolerance of M. aquaticum to high NH4+. Herein, the responses of M. aquaticum to GS inhibition by 0.1 mM methionine sulfoximine (MSX) under 15 mM NH4+ were investigated. After 5 days, visible NH4+ toxicity symptoms were observed in MSX-treated plants. Compared with the control, the NH4+ accumulation in the leaves increased by 20.99 times, while that of stems and roots increased by 3.27 times and 47.76 %, suggesting that GS inhibition had a greater impact on the leaves. GS inhibition decreased pigments in the leaves by 8.64 %-41.06 %, triggered oxidative stress, and affected ions concentrations in M. aquaticum. The concentrations of glutamine (Gln) and asparagine decreased by 63.46 %-97.43 % and 12.37 %-76.41 %, respectively, while the concentrations of most other amino acids increased after 5 days of MSX treatment, showing that GS inhibition reprogrammed the amino acids synthesis. A decrease in Gln explains the regulations of N-related genes, including increased expression of AMT in roots and decreased expression of GS, GOGAT, GDH, and AS, which would cause further NH4+ accumulation via promoting NH4+ uptake and decreasing NH4+ assimilation in M. aquaticum. This study revealed for the first time that GS inhibition under high NH4+ condition can lead to phytotoxicity in M. aquaticum due to NH4+ accumulation. The physiological and molecular responses of the leaves, stems, and roots confirmed the importance of GS in the high NH4+ tolerance of M. aquaticum. These findings provide new insights into NH4+ tolerance mechanisms in M. aquaticum and a theoretical foundation for the phytoremediation of high NH4+-loaded swine wastewater.
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Affiliation(s)
- Ying Zhang
- Key Laboratory of Agro-ecological Processes in Subtropical Region/Changsha Research Station for Agricultural and Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan 410125, PR China; College of Resources and Environment, Hunan Agricultural University, Changsha, Hunan 410128, PR China
| | - Baozhen Li
- Key Laboratory of Agro-ecological Processes in Subtropical Region/Changsha Research Station for Agricultural and Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan 410125, PR China.
| | - Pei Luo
- Key Laboratory of Agro-ecological Processes in Subtropical Region/Changsha Research Station for Agricultural and Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan 410125, PR China
| | - Yingnan Xian
- Key Laboratory of Agro-ecological Processes in Subtropical Region/Changsha Research Station for Agricultural and Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan 410125, PR China
| | - Runlin Xiao
- Key Laboratory of Agro-ecological Processes in Subtropical Region/Changsha Research Station for Agricultural and Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan 410125, PR China
| | - Jinshui Wu
- Key Laboratory of Agro-ecological Processes in Subtropical Region/Changsha Research Station for Agricultural and Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan 410125, PR China
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Kong L, Zhang Y, Zhang B, Li H, Wang Z, Si J, Fan S, Feng B. Does energy cost constitute the primary cause of ammonium toxicity in plants? PLANTA 2022; 256:62. [PMID: 35994155 DOI: 10.1007/s00425-022-03971-7] [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: 06/27/2022] [Accepted: 08/09/2022] [Indexed: 06/15/2023]
Abstract
Nitrate (NO3-) and ammonium (NH4+) are the main nitrogen (N) sources and key determinants for plant growth and development. In recent decades, NH4+, which is a double-sided N compound, has attracted considerable amounts of attention from researchers. Elucidating the mechanisms of NH4+ toxicity and exploring the means to overcome this toxicity are necessary to improve agricultural sustainability. In this review, we discuss the current knowledge concerning the energy consumption and production underlying NH4+ metabolism and toxicity in plants, such as N uptake; assimilation; cellular pH homeostasis; and functions of the plasma membrane (PM), vacuolar H+-ATPase and H+-pyrophosphatase (H+-PPase). We also discuss whether the overconsumption of energy is the primary cause of NH4+ toxicity or constitutes a fundamental strategy for plants to adapt to high-NH4+ stress. In addition, the effects of regulators on energy production and consumption and other physiological processes are listed for evaluating the possibility of high energy costs associated with NH4+ toxicity. This review is helpful for exploring the tolerance mechanisms and for developing NH4+-tolerant varieties as well as agronomic techniques to alleviate the effects of NH4+ stress in the field.
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Affiliation(s)
- Lingan Kong
- Crop Research Institute, Shandong Academy of Agricultural Sciences, 23788 Gongyebei Road, Jinan, 250100, China
- College of Life Science, Shandong Normal University, Jinan, 250014, China
| | - Yunxiu Zhang
- Crop Research Institute, Shandong Academy of Agricultural Sciences, 23788 Gongyebei Road, Jinan, 250100, China
| | - Bin Zhang
- Crop Research Institute, Shandong Academy of Agricultural Sciences, 23788 Gongyebei Road, Jinan, 250100, China
| | - Huawei Li
- Crop Research Institute, Shandong Academy of Agricultural Sciences, 23788 Gongyebei Road, Jinan, 250100, China
| | - Zongshuai Wang
- Crop Research Institute, Shandong Academy of Agricultural Sciences, 23788 Gongyebei Road, Jinan, 250100, China
| | - Jisheng Si
- Crop Research Institute, Shandong Academy of Agricultural Sciences, 23788 Gongyebei Road, Jinan, 250100, China
| | - Shoujin Fan
- College of Life Science, Shandong Normal University, Jinan, 250014, China.
| | - Bo Feng
- Crop Research Institute, Shandong Academy of Agricultural Sciences, 23788 Gongyebei Road, Jinan, 250100, China.
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Yu Q, Wang H, Wang H, Xu C, Liu M, Ma Y, Li Y, Ma S, Hamilton DP, Jeppesen E. Effects of High Ammonium Loading on Two Submersed Macrophytes of Different Growth Form Based on an 18-Month Pond Experiment. FRONTIERS IN PLANT SCIENCE 2022; 13:939589. [PMID: 35909745 PMCID: PMC9330597 DOI: 10.3389/fpls.2022.939589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 06/14/2022] [Indexed: 06/15/2023]
Abstract
Ammonium (NH4-N) produces a paradoxical effect on submersed macrophytes because it is not only the preferred nitrogen source for the growth of plants but also threatens the growth of plants at high concentration. Whether short-term and small-scale physiological toxicity experiments at an individual level can reflect the effects of high ammonium on populations of submersed macrophytes in natural conditions is still unclear. In this study, an 18-month experiment was conducted in six 600 m2 ponds subjected to different levels of ammonium loading. The effects of high ammonium on populations of canopy-forming Myriophyllum spicatum and rosette-forming Vallisneria natans were explored. The results showed that M. spicatum and V. natans populations can develop high cover and height at high ammonium concentration (7 mg/L) at short-term exposures, and V. natans may be tolerant to 18 mg/L ammonium concentration. However, the cover of M. spicatum and the height of both species were inhibited at 2.4 mg/L at long-term exposures. The height of M. spicatum was two to six times higher than that of V. natans across all treatments and control by the end of the experiment, and the cover of M. spicatum was 7-11 times higher than that of V. natans in most NH4-N loading treatments, except the cover of M. spicatum in the highest NH4-N loading treatment with 18 mg/L NH4-N. The rosette-forming V. natans resists ammonium stress by slow growth (shoot elongation) to reduce consumption, while canopy-forming species resist ammonium stress by shoot elongation and canopy development to capture light. Although increasing ammonium concentration may induce severe stress on M. spicatum, the morphological characteristics of this species may, to some extent, release the plants from this stress. Our present study indicates that the negative effects of ammonium stress on the development of populations increased with exposure duration, and the submersed macrophyte community with stronger ability for light capture and dispersal may resist high ammonium stress. Nevertheless, in strongly ammonium-enriched systems, competition and succession cannot be neglected.
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Affiliation(s)
- Qing Yu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- School of Life Sciences, Institute of Ecology and Biodiversity, Shandong University, Qingdao, China
| | - Haijun Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- School of Ecology and Environmental Science, Institute for Ecological Research and Pollution Control of Plateau Lakes, Yunnan University, Kunming, China
| | - Hongzhu Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Chao Xu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Miao Liu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Yu Ma
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- College of Fisheries and Life Science, Dalian Ocean University, Dalian, China
| | - Yan Li
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Shuonan Ma
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- School of Marine Sciences, Ningbo University, Ningbo, China
| | - David P. Hamilton
- Australian Rivers Institute, Griffith University, Nathan, QLD, Australia
| | - Erik Jeppesen
- Department of Ecoscience, WATEC, Aarhus University, Aarhus, Denmark
- Sino-Danish Center for Education and Research, Beijing, China
- Limnology Laboratory, Department of Biological Sciences, Middle East Technical University, Ankara, Turkey
- Centre for Ecosystem Research and Implementation, Middle East Technical University, Ankara, Turkey
- Institute of Marine Sciences, Middle East Technical University, Erdemli, Turkey
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Wang H, Tang X, Chen J, Shang S, Zhu M, Liang S, Zang Y. Comparative studies on the response of Zostera marina leaves and roots to ammonium stress and effects on nitrogen metabolism. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2021; 240:105965. [PMID: 34543784 DOI: 10.1016/j.aquatox.2021.105965] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 09/04/2021] [Accepted: 09/07/2021] [Indexed: 06/13/2023]
Abstract
Coastal eutrophication has resulted in the rapid loss and deterioration of seagrass beds worldwide. The high concentration of ammonium in eutrophic aquatic environments has been invoked as the main cause. In this study, leaves and roots of the seagrass Zostera marina were treated with simulated eutrophic seawater with elevated ammonium concentrations. The tolerance to ammonium stress and mechanism of nitrogen metabolism detoxification in different tissues were investigated. The results showed that high ammonium stress significantly affected the growth of leaves and had a negative effect on photosynthesis. The root activity of Z. marina was not inhibited at ammonium concentrations of ≤100 mg/L, indicating that the roots exhibited tolerance to ammonium stress. Increasing ammonium concentrations led to a higher increase of ammonium and free amino acid (FAA) contents in leaves than in roots. However, nitrogen storage decreased in Z. marina leaves after high ammonium treatments. The enzyme activity and gene expression of glutamine synthetase (GS) in roots were significantly higher than in the leaves even under ammonium stress. Meanwhile, ammonium stress increased the enzyme activities and gene expression of glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH) in roots, which suggested that the roots had a strong ability to assimilate ammonium under ammonium stress. In contrast, although the GOGAT and GDH activity and gene expression in the leaves were initially increased, they significantly decreased when the ammonium concentration exceeded 100 mg/L. These results indicated that the concentration of 100 mg/L might be a threshold marking a transition from tolerance to toxicity for the leaves. Our study demonstrates that Z. marina leaves could be prone to higher damage than roots because the mechanism of ammonium assimilation in leaves is more susceptible to ammonium toxicity.
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Affiliation(s)
- Hongrui Wang
- College of Marine Life Sciences, Ocean University of China, Qingdao, Shandong, PR China
| | - Xuexi Tang
- College of Marine Life Sciences, Ocean University of China, Qingdao, Shandong, PR China
| | - Jun Chen
- College of Marine Life Sciences, Ocean University of China, Qingdao, Shandong, PR China
| | - Shuai Shang
- College of Biological and Environmental Engineering, Binzhou University, Binzhou, Shandong, PR China
| | - Meiling Zhu
- College of Marine Life Sciences, Ocean University of China, Qingdao, Shandong, PR China
| | - Shuo Liang
- College of Marine Life Sciences, Ocean University of China, Qingdao, Shandong, PR China
| | - Yu Zang
- Key Laboratory of Marine Eco-Environmental Science and Technology, First Institute of Oceanography, Ministry of Natural Resources, Qingdao, Shandong, PR China.
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