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Al-Mamun MH, Cazzonelli CI, Krishna P. BZR1 and BES1 transcription factors mediate brassinosteroid control over root system architecture in response to nitrogen availability. FRONTIERS IN PLANT SCIENCE 2024; 15:1387321. [PMID: 38779077 PMCID: PMC11109456 DOI: 10.3389/fpls.2024.1387321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Accepted: 04/17/2024] [Indexed: 05/25/2024]
Abstract
Plants modify their root system architecture (RSA) in response to nitrogen (N) deficiency. The plant steroidal hormone, brassinosteroid (BR), plays important roles in root growth and development. This study demonstrates that optimal levels of exogenous BR impact significant increases in lateral root length and numbers in Arabidopsis seedlings under mild N-deficient conditions as compared to untreated seedlings. The impact of BR on RSA was stronger under mild N deficiency than under N-sufficient conditions. The BR effects on RSA were mimicked in dominant mutants of BZR1 and BES1 (bzr1-1D and bes1-D) transcription factors, while the RSA was highly reduced in the BR-insensitive mutant bri1-6, confirming that BR signaling is essential for the development of RSA under both N-sufficient and N-deficient conditions. Exogenous BR and constitutive activity of BZR1 and BES1 in dominant mutants led to enhanced root meristem, meristematic cell number, and cortical cell length. Under mild N deficiency, bzr1-1D displayed higher fresh and dry shoot weights, chlorophyll content, and N levels in the shoot, as compared to the wild type. These results indicate that BR modulates RSA under both N-sufficient and N-deficient conditions via the transcription factors BES1/BZR1 module and confers tolerance to N deficiency.
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Affiliation(s)
| | | | - Priti Krishna
- School of Science, Western Sydney University, Richmond, NSW, Australia
- Faculty of Life Sciences, Graphic Era Deemed to be University, Dehradun, Uttarakhand, India
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Li Z, Gao J, Wang S, Xie X, Wang Z, Peng Y, Yang X, Pu W, Wang Y, Fan X. Comprehensive analysis of the LHT gene family in tobacco and functional characterization of NtLHT22 involvement in amino acids homeostasis. FRONTIERS IN PLANT SCIENCE 2022; 13:927844. [PMID: 36176688 PMCID: PMC9513474 DOI: 10.3389/fpls.2022.927844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 08/15/2022] [Indexed: 06/16/2023]
Abstract
Amino acids are vital nitrogen (N) sources for plant growth, development, and yield. The uptake and translocation of amino acids are mediated by amino acid transporters (AATs). The AATs family including lysine-histidine transporters (LHTs), amino acid permeases (AAPs), and proline transporters (ProTs) subfamilies have been identified in various plants. However, little is known about these genes in tobacco. In this study, we identified 23 LHT genes, the important members of AATs, in the tobacco genome. The gene structure, phylogenetic tree, transmembrane helices, chromosomal distribution, cis-regulatory elements, and expression profiles of NtLHT genes were systematically analyzed. Phylogenetic analysis divided the 23 NtLHT genes into two conserved subgroups. Expression profiles confirmed that the NtLHT genes were differentially expressed in various tissues, indicating their potential roles in tobacco growth and development. Cis-elements analysis of promoters and expression patterns after stress treatments suggested that NtLHT genes probable participate in abiotic stress responses of tobacco. In addition, Knock out and overexpression of NtLHT22 changed the amino acids homeostasis in the transgenic plants, the contents of amino acids were significantly decreased in NtLHT22 overexpression plants than wild-type. The results from this study provide important information for further studies on the molecular functions of the NtLHT genes.
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Affiliation(s)
- Zhaowu Li
- Tobacco Research Institute of Technology Centre, China Tobacco Hunan Industrial Corporation, Changsha, China
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Ministry of Agriculture Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing, China
| | - Junping Gao
- Tobacco Research Institute of Technology Centre, China Tobacco Hunan Industrial Corporation, Changsha, China
| | - Shuaibin Wang
- Tobacco Research Institute of Technology Centre, China Tobacco Hunan Industrial Corporation, Changsha, China
| | - Xiaodong Xie
- China Tobacco Gene Research Center, Zhengzhou Tobacco Research Institute of China National Tobacco Corporation, Zhengzhou, China
| | - Zhangying Wang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Yu Peng
- Tobacco Research Institute of Technology Centre, China Tobacco Hunan Industrial Corporation, Changsha, China
| | - Xiaonian Yang
- Tobacco Research Institute of Technology Centre, China Tobacco Hunan Industrial Corporation, Changsha, China
| | - Wenxuan Pu
- Tobacco Research Institute of Technology Centre, China Tobacco Hunan Industrial Corporation, Changsha, China
| | - Yaofu Wang
- Tobacco Research Institute of Technology Centre, China Tobacco Hunan Industrial Corporation, Changsha, China
| | - Xiaorong Fan
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Ministry of Agriculture Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing, China
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Burnett MS, Schütte UM, Harms TK. WIDESPREAD CAPACITY FOR DENITRIFICATION ACROSS A BOREAL FOREST LANDSCAPE. BIOGEOCHEMISTRY 2022; 158:215-232. [PMID: 36186670 PMCID: PMC9518932 DOI: 10.1007/s10533-022-00895-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 01/18/2022] [Indexed: 06/16/2023]
Abstract
A warming climate combined with frequent and severe fires cause permafrost to thaw, especially in the region of discontinuous permafrost, where soil temperatures may only be a few degrees below 0 °C. Soil thaw releases carbon (C) and nitrogen (N) into the actively cycling pools, and whereas C emissions following permafrost thaw are well documented, the fates of N remain unclear. Denitrification could release N from ecosystems as nitrous oxide (N2O) or nitrogen gas (N2), but the contributions of these processes to the high-latitude N cycle remain uncertain. We quantified microbial capacity for denitrification and N2O production in boreal soils, lakes, and streams using anoxic C- and N-amended assays, and assessed correlates of denitrifying enzyme activity (DEA) in Interior Alaska. Riparian soils and stream sediments supported the highest potential rates of denitrification, upland soils were intermediate, and lakes supported lower rates, whereas deep permafrost soils supported little denitrification. Time since fire had no effect on denitrification potential in upland soils. Across all landscape positions, DEA was negatively correlated with ammonium pools. Within each landscape position, potential rate of denitrification increased with soil or sediment organic matter content. Widespread N loss to denitrification in boreal forests could constrain the capacity for N-limited primary producers to maintain C stocks in soils following permafrost thaw.
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Affiliation(s)
- Melanie S. Burnett
- Institute of Arctic Biology and Department of Biology & Wildlife, University of Alaska Fairbanks, Fairbanks, Alaska 99775, United States of America
- Department of Earth and Planetary Science, McGill University, Montréal, Quebec H3A 2A7, Canada
| | - Ursel M.E. Schütte
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska 99775, United States of America
| | - Tamara K. Harms
- Institute of Arctic Biology and Department of Biology & Wildlife, University of Alaska Fairbanks, Fairbanks, Alaska 99775, United States of America
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Liu W, Xue K, Hu R, Zhou J, Van Nostrand JD, Dimitrou J, Giagnoni L, Renella G. Long-Term Effects of Soil Remediation with Willow Short Rotation Coppice on Biogeographic Pattern of Microbial Functional Genes. Microorganisms 2022; 10:microorganisms10010140. [PMID: 35056589 PMCID: PMC8777967 DOI: 10.3390/microorganisms10010140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/01/2022] [Accepted: 01/07/2022] [Indexed: 12/02/2022] Open
Abstract
Short rotation coppice (SRC) is increasingly being adopted for bioenergy production, pollution remediation and land restoration. However, its long-term effects on soil microbial communities are poorly characterized. Here, we studied soil microbial functional genes and their biogeographic pattern under SRC with willow trees as compared to those under permanent grassland (C). GeoChip analysis showed a lower functional gene diversity in SRC than in C soil, whereas microbial ATP and respiration did not change. The SRC soil had lower relative abundances of microbial genes encoding for metal(-oid) resistance, antibiotic resistance and stress-related proteins. This indicates a more benign habitat under SRC for microbial communities after relieving heavy metal stress, consistent with the lower phytoavailability of some metals (i.e., As, Cd, Ni and Zn) and higher total organic carbon, NO3−-N and P concentrations. The microbial taxa–area relationship was valid in both soils, but the space turnover rate was higher under SRC within 0.125 m2, which was possibly linked to a more benign environment under SRC, whereas similar values were reached beyond thisarea. Overall, we concluded that SRC management can be considered as a phytotechnology that ameliorates the habitat for soil microorganisms, owing to TOC and nutrient enrichment on the long-term.
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Affiliation(s)
- Wenjing Liu
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, China;
| | - Kai Xue
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, China;
- Beijing Yanshan Earth Critical Zone National Research Station, University of Chinese Academy of Sciences, Beijing 101408, China
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Chinese Academy of Sciences, Xining 810001, China
- Correspondence: (K.X.); (G.R.)
| | - Runpeng Hu
- Department of Biological Sciences, Smith College, Northampton, MA 01063, USA;
| | - Jizhong Zhou
- Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK 73019, USA; (J.Z.); (J.D.V.N.)
| | - Joy D. Van Nostrand
- Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK 73019, USA; (J.Z.); (J.D.V.N.)
| | - Jannis Dimitrou
- Department of Crop Production Ecology, Swedish University of Agricultural Sciences, 75007 Uppsala, Sweden;
| | - Laura Giagnoni
- Department of Civil Engineering, Architecture, Environmental and Mathematics (DICATAM), University of Brescia, via Branze 43, 25123 Brescia, Italy;
| | - Giancarlo Renella
- Department of Agronomy, Food, Natural Resources, Animals and the Environment, University of Padova, viale dell’Università 16, 35020 Legnaro, Italy
- Correspondence: (K.X.); (G.R.)
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Li F, Dong C, Yang T, Bao S, Fang W, Lucas WJ, Zhang Z. The tea plant CsLHT1 and CsLHT6 transporters take up amino acids, as a nitrogen source, from the soil of organic tea plantations. HORTICULTURE RESEARCH 2021; 8:178. [PMID: 34333546 PMCID: PMC8325676 DOI: 10.1038/s41438-021-00615-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/09/2021] [Accepted: 05/20/2021] [Indexed: 06/13/2023]
Abstract
Organic tea is more popular than conventional tea that originates from fertilized plants. Amino acids inorganic soils constitute a substantial pool nitrogen (N) available for plants. However, the amino-acid contents in soils of tea plantations and how tea plants take up these amino acids remain largely unknown. In this study, we show that the amino-acid content in the soil of an organic tea plantation is significantly higher than that of a conventional tea plantation. Glutamate, alanine, valine, and leucine were the most abundant amino acids in the soil of this tea plantation. When 15N-glutamate was fed to tea plants, it was efficiently absorbed and significantly increased the contents of other amino acids in the roots. We cloned seven CsLHT genes encoding amino-acid transporters and found that the expression of CsLHT1, CsLHT2, and CsLHT6 in the roots significantly increased upon glutamate feeding. Moreover, the expression of CsLHT1 or CsLHT6 in a yeast amino-acid uptake-defective mutant, 22∆10α, enabled growth on media with amino acids constituting the sole N source. Amino-acid uptake assays indicated that CsLHT1 and CsLHT6 are H+-dependent high- and low-affinity amino-acid transporters, respectively. We further demonstrated that CsLHT1 and CsLHT6 are highly expressed in the roots and are localized to the plasma membrane. Moreover, overexpression of CsLHT1 and CsLHT6 in Arabidopsis significantly improved the uptake of exogenously supplied 15N-glutamate and 15N-glutamine. Taken together, our findings are consistent with the involvement of CsLHT1 and CsLHT6 in amino-acid uptake from the soil, which is particularly important for tea plants grown inorganic tea plantations.
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Affiliation(s)
- Fang Li
- State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, Anhui, 230036, China
- College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Chunxia Dong
- State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Tianyuan Yang
- State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Shilai Bao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Wanping Fang
- College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China
| | - William J Lucas
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, 95616, USA
| | - Zhaoliang Zhang
- State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, Anhui, 230036, China.
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Daly AB, Jilling A, Bowles TM, Buchkowski RW, Frey SD, Kallenbach CM, Keiluweit M, Mooshammer M, Schimel JP, Grandy AS. A holistic framework integrating plant-microbe-mineral regulation of soil bioavailable nitrogen. BIOGEOCHEMISTRY 2021; 154:211-229. [PMID: 34759436 PMCID: PMC8570341 DOI: 10.1007/s10533-021-00793-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 04/06/2021] [Indexed: 06/01/2023]
Abstract
UNLABELLED Soil organic nitrogen (N) is a critical resource for plants and microbes, but the processes that govern its cycle are not well-described. To promote a holistic understanding of soil N dynamics, we need an integrated model that links soil organic matter (SOM) cycling to bioavailable N in both unmanaged and managed landscapes, including agroecosystems. We present a framework that unifies recent conceptual advances in our understanding of three critical steps in bioavailable N cycling: organic N (ON) depolymerization and solubilization; bioavailable N sorption and desorption on mineral surfaces; and microbial ON turnover including assimilation, mineralization, and the recycling of microbial products. Consideration of the balance between these processes provides insight into the sources, sinks, and flux rates of bioavailable N. By accounting for interactions among the biological, physical, and chemical controls over ON and its availability to plants and microbes, our conceptual model unifies complex mechanisms of ON transformation in a concrete conceptual framework that is amenable to experimental testing and translates into ideas for new management practices. This framework will allow researchers and practitioners to use common measurements of particulate organic matter (POM) and mineral-associated organic matter (MAOM) to design strategic organic N-cycle interventions that optimize ecosystem productivity and minimize environmental N loss. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s10533-021-00793-9.
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Affiliation(s)
- Amanda B. Daly
- Department of Natural Resources and the Environment, University of New Hampshire, 56 College Road, Durham, NH 03824 USA
| | - Andrea Jilling
- Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK USA
| | - Timothy M. Bowles
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA USA
| | | | - Serita D. Frey
- Department of Natural Resources and the Environment, University of New Hampshire, 56 College Road, Durham, NH 03824 USA
| | | | - Marco Keiluweit
- School of Earth & Sustainability and Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA USA
| | - Maria Mooshammer
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA USA
| | - Joshua P. Schimel
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA USA
| | - A. Stuart Grandy
- Department of Natural Resources and the Environment, University of New Hampshire, 56 College Road, Durham, NH 03824 USA
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7
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Bueno CG, Gerz M, Moora M, Leon D, Gomez-Garcia D, de Leon DG, Font X, Al-Quraishy S, Hozzein WN, Zobel M. Distribution of plant mycorrhizal traits along an elevational gradient does not fully mirror the latitudinal gradient. MYCORRHIZA 2021; 31:149-159. [PMID: 33475799 DOI: 10.1007/s00572-020-01012-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 12/04/2020] [Indexed: 06/12/2023]
Abstract
The influence of mycorrhizal symbiosis on ecosystem processes depends on the mycorrhizal type and status of plants. Early research hypothesized that the proportion of arbuscular mycorrhizal (AM) species decreases and of ectomycorrhizal (ECM) and ericoid mycorrhizal (ERM) species increases along increasing elevations and latitudes. However, there is very scarce information about this pattern along elevation gradients. We aimed to test this hypothesis and to describe the trends in plant mycorrhizal status by examining the Pyrenean mountain range (from 400 to 3400 m asl). The distribution of plant mycorrhizal types: AM, ECM, ERM, and non-mycorrhizal (NM) and status (obligately, OM, or facultatively, FM mycorrhizal plants, FM) were identified based on the Pyrenean Floristic Atlas and analyzed for climatic and edaphic drivers. The proportion of AM plants decreased slightly with elevation, while ECM species peaked at 1000 m asl. The proportion of ERM and NM plant species rose with increasing elevation. The proportion of FM species increased, and OM species decreased with increasing elevation. The change of AM and ECM species, and OM and FM species, along the elevational gradient, corresponds broadly to changes along the latitudinal gradient, driven by a combination of climatic and edaphic factors. Differently, the elevational occurrence of NM plant species is mainly driven only by climatic factors (low temperature) and that of ERM species by only edaphic factors (low pH). Large-scale macroecological studies (≥ 50 km grid cell) well reflect the effects of climate on the distribution of plant mycorrhizal traits, but local data (≤ 1 km grid cell) are needed to understand the effects of soil conditions and land use.
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Affiliation(s)
- C Guillermo Bueno
- Institute of Ecology and Earth Sciences, University of Tartu, Lai 40, 51005, Tartu, Estonia.
| | - M Gerz
- Institute of Ecology and Earth Sciences, University of Tartu, Lai 40, 51005, Tartu, Estonia
| | - M Moora
- Institute of Ecology and Earth Sciences, University of Tartu, Lai 40, 51005, Tartu, Estonia
| | - D Leon
- Institute of Ecology and Earth Sciences, University of Tartu, Lai 40, 51005, Tartu, Estonia
| | - D Gomez-Garcia
- Pyrenean Institute of Ecology (IPE-CSIC), Av. Ntra. Sra. de la Victoria, S/N, 22700, Jaca, Spain
| | - D García de Leon
- Department of Life Sciences, University of Alcalá, Alcalá de Henares, 28805, Spain
| | - X Font
- Plant Biodiversity Resource Centre, University of Barcelona, Carrer de Baldiri Reixac 2, 08028, Barcelona, Spain
| | - Saleh Al-Quraishy
- Zoology Department, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia
| | - Wael N Hozzein
- Zoology Department, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia
- Botany and Microbiology Department, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt
| | - M Zobel
- Institute of Ecology and Earth Sciences, University of Tartu, Lai 40, 51005, Tartu, Estonia
- Zoology Department, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia
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Farzadfar S, Knight JD, Congreves KA. Soil organic nitrogen: an overlooked but potentially significant contribution to crop nutrition. PLANT AND SOIL 2021; 462:7-23. [PMID: 34720208 PMCID: PMC8550315 DOI: 10.1007/s11104-021-04860-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 01/18/2021] [Accepted: 01/25/2021] [Indexed: 05/02/2023]
Abstract
BACKGROUND For more than a century, crop N nutrition research has primarily focused on inorganic N (IN) dynamics, building the traditional model that agricultural plants predominantly take up N in the form of NO3 - and NH4 +. However, results reported in the ecological and agricultural literature suggest that the traditional model of plant N nutrition is oversimplified. SCOPE We examine the role of organic N (ON) in plant N nutrition, first by reviewing the historical discoveries by ecologists of plant ON uptake, then by discussing the advancements of key analytical techniques that have furthered the cause (stable isotope and microdialysis techniques). The current state of knowledge on soil ON dynamics is analyzed concurrently with recent developments that show ON uptake and assimilation by agricultural plant species. Lastly, we consider the relationship between ON uptake and nitrogen use efficiency (NUE) in an agricultural context. CONCLUSIONS We propose several mechanisms by which ON uptake and assimilation may increase crop NUE, such as by reducing N assimilation costs, promoting root biomass growth, shaping N cycling microbial communities, recapturing exuded N compounds, and aligning the root uptake capacity to the soil N supply in highly fertilized systems. These hypothetical mechanisms should direct future research on the topic. Although the quantitative role remains unknown, ON compounds should be considered as significant contributors to plant N nutrition.
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Affiliation(s)
- Soudeh Farzadfar
- Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8 Canada
| | - J. Diane Knight
- Department of Soil Science, University of Saskatchewan, Saskatoon, SK S7N 5A8 Canada
| | - Kate A. Congreves
- Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8 Canada
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Wang J, Long Z, Min W, Hou Z. Metagenomic analysis reveals the effects of cotton straw-derived biochar on soil nitrogen transformation in drip-irrigated cotton field. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:43929-43941. [PMID: 32743698 DOI: 10.1007/s11356-020-10267-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 07/23/2020] [Indexed: 06/11/2023]
Abstract
Biochar has been widely accepted as a soil amendment to improve nitrogen (N) use efficiency, but the effect of biochar on N transformation metabolic pathways is unclear. A field experiment was conducted to evaluate the effect of biochar on N transformation in drip-irrigated cotton field. Four treatments were set as (1) no N fertilization (CK), (2) N fertilizer application at 300 kg ha-1 (N300), (3) N fertilizer application plus cotton straw (N300+ST), and (4) N fertilizer application plus cotton straw-derived biochar (N300+BC). Result showed that soil total N in N300+ST and N300+BC was 16.3% and 24.9% higher than that in N300, respectively. Compared with N300+ST, the nitrate N (NO3--N) in N300+BC was significantly increased. Acidolyzable N and non-acidolyzable N in N300+ST and N300+BC were higher than those in CK and N300, while N300+BC performed better than N300+ST. Furthermore, the N fertilizer use efficiency of cotton in N300+ST and N300+BC was 15.1% and 23.2% higher than that in N300, respectively. Both N fertilizer incorporations with straw and biochar significantly altered the microbial community structures and N metabolic pathways. Genes related to denitrification and nitrate reduction in N300+ST were higher than those in N300, and N300+BC significantly increased nitrification and glutamate synthesis genes. Therefore, N fertilizer application plus cotton straw-derived biochar changed the microbial community composition, increased nitrification and glutamate synthesis enzyme genes which were beneficial to the accumulation of soil N content, and improved soil N retention capacity thus to increase N fertilizer use efficiency.
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Affiliation(s)
- Jing Wang
- Department of Resources and Environmental Science, Shihezi University, Shihezi, 832003, Xinjiang, People's Republic of China
| | - Zehua Long
- Department of Resources and Environmental Science, Shihezi University, Shihezi, 832003, Xinjiang, People's Republic of China
| | - Wei Min
- Department of Resources and Environmental Science, Shihezi University, Shihezi, 832003, Xinjiang, People's Republic of China
| | - Zhenan Hou
- Department of Resources and Environmental Science, Shihezi University, Shihezi, 832003, Xinjiang, People's Republic of China.
- Agriculture College, Shihezi University, Box #425, Shihezi, Xinjiang, 832003, China.
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10
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Jia Z, von Wirén N. Signaling pathways underlying nitrogen-dependent changes in root system architecture: from model to crop species. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:4393-4404. [PMID: 31970412 PMCID: PMC7382383 DOI: 10.1093/jxb/eraa033] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 01/22/2020] [Indexed: 05/16/2023]
Abstract
Among all essential mineral elements, nitrogen (N) is required in the largest amounts and thus is often a limiting factor for plant growth. N is taken up by plant roots in the form of water-soluble nitrate, ammonium, and, depending on abundance, low-molecular weight organic N. In soils, the availability and composition of these N forms can vary over space and time, which exposes roots to various local N signals that regulate root system architecture in combination with systemic signals reflecting the N nutritional status of the shoot. Uncovering the molecular mechanisms underlying N-dependent signaling provides great potential to optimize root system architecture for the sake of higher N uptake efficiency in crop breeding. In this review, we summarize prominent signaling mechanisms and their underlying molecular players that derive from external N forms or the internal N nutritional status and modulate root development including root hair formation and gravitropism. We also compare the current state of knowledge of these pathways between Arabidopsis and graminaceous plant species.
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Affiliation(s)
- Zhongtao Jia
- Molecular Plant Nutrition, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D-06466 Stadt Seeland, OT Gatersleben, Germany
| | - Nicolaus von Wirén
- Molecular Plant Nutrition, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D-06466 Stadt Seeland, OT Gatersleben, Germany
- Correspondence:
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11
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Walczyk AM, Hersch-Green EI. Impacts of soil nitrogen and phosphorus levels on cytotype performance of the circumboreal herb Chamerion angustifolium: implications for polyploid establishment. AMERICAN JOURNAL OF BOTANY 2019; 106:906-921. [PMID: 31283844 DOI: 10.1002/ajb2.1321] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 04/24/2019] [Indexed: 06/09/2023]
Abstract
PREMISE Although polyploidy commonly occurs in angiosperms, not all polyploidization events lead to successful lineages, and environmental conditions could influence cytotype dynamics and polyploid success. Low soil nitrogen and/or phosphorus concentrations often limit ecosystem primary productivity, and changes in these nutrients might differentially favor some cytotypes over others, thereby influencing polyploid establishment. METHODS We grew diploid, established tetraploid, and neotetraploid Chamerion angustifolium (fireweed) in a greenhouse under low and high soil nitrogen and phosphorus conditions and different competition treatments and measured plant performance (height, biomass, flower production, and root bud production) and insect damage responses. By comparing neotetraploids to established tetraploids, we were able to examine traits and responses that might directly arise from polyploidization before they are modified by natural selection and/or genetic drift. RESULTS We found that (1) neopolyploids were the least likely to survive and flower and experienced the most herbivore damage, regardless of nutrient conditions; (2) both neo- and established tetraploids had greater biomass and root bud production under nutrient-enriched conditions, whereas diploid biomass and root bud production was not significantly affected by nutrients; and (3) intra-cytotype competition more negatively affected diploids and established tetraploids than it did neotetraploids. CONCLUSIONS Following polyploidization, biomass and clonal growth might be more immediately affected by environmental nutrient availabilities than plant survival, flowering, and/or responses to herbivory, which could influence competitive dynamics. Specifically, polyploids might have competitive and colonizing advantages over diploids under nutrient-enriched conditions favoring their establishment, although establishment may also depend upon the density and occurrences of other related cytotypes in a population.
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Affiliation(s)
- Angela M Walczyk
- Department of Biological Sciences, Michigan Technological University, Houghton, Michigan, 49931, USA
| | - Erika I Hersch-Green
- Department of Biological Sciences, Michigan Technological University, Houghton, Michigan, 49931, USA
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12
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Graham EB, Yang F, Bell S, Hofmockel KS. High Genetic Potential for Proteolytic Decomposition in Northern Peatland Ecosystems. Appl Environ Microbiol 2019; 85:e02851-18. [PMID: 30850433 PMCID: PMC6498154 DOI: 10.1128/aem.02851-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 02/13/2019] [Indexed: 11/28/2022] Open
Abstract
Nitrogen (N) is a scarce nutrient commonly limiting primary productivity. Microbial decomposition of complex carbon (C) into small organic molecules (e.g., free amino acids) has been suggested to supplement biologically fixed N in northern peatlands. We evaluated the microbial (fungal, bacterial, and archaeal) genetic potential for organic N depolymerization in peatlands at Marcell Experimental Forest (MEF) in northern Minnesota. We used guided gene assembly to examine the abundance and diversity of protease genes and further compared them to those of N fixation (nifH) genes in shotgun metagenomic data collected across depths and in two distinct peatland environments (bogs and fens). Microbial protease genes greatly outnumbered nifH genes, with the most abundant genes (archaeal M1 and bacterial trypsin [S01]) each containing more sequences than all sequences attributed to nifH Bacterial protease gene assemblies were diverse and abundant across depth profiles, indicating a role for bacteria in releasing free amino acids from peptides through depolymerization of older organic material and contrasting with the paradigm of fungal dominance in depolymerization in forest soils. Although protease gene assemblies for fungi were much less abundant overall than those for bacteria, fungi were prevalent in surface samples and therefore may be vital in degrading large soil polymers from fresh plant inputs during the early stage of depolymerization. In total, we demonstrate that depolymerization enzymes from a diverse suite of microorganisms, including understudied bacterial and archaeal lineages, are prevalent within northern peatlands and likely to influence C and N cycling.IMPORTANCE Nitrogen (N) is a common limitation on primary productivity, and its source remains unresolved in northern peatlands that are vulnerable to environmental change. Decomposition of complex organic matter into free amino acids has been proposed as an important N source, but the genetic potential of microorganisms mediating this process has not been examined. Such information can inform possible responses of northern peatlands to environmental change. We show high genetic potential for microbial production of free amino acids across a range of microbial guilds in northern peatlands. In particular, the abundance and diversity of bacterial genes encoding proteolytic activity suggest a predominant role for bacteria in regulating productivity and contrasts with a paradigm of fungal dominance of organic N decomposition. Our results expand our current understanding of coupled carbon and nitrogen cycles in northern peatlands and indicate that understudied bacterial and archaeal lineages may be central in this ecosystem's response to environmental change.
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Affiliation(s)
- Emily B Graham
- Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Fan Yang
- Department of Agricultural & Biosystems Engineering, Iowa State University, Ames, Iowa, USA
| | - Sheryl Bell
- Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Kirsten S Hofmockel
- Pacific Northwest National Laboratory, Richland, Washington, USA
- Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, Iowa, USA
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13
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Bales AL, Hersch‐Green EI. Effects of soil nitrogen on diploid advantage in fireweed, Chamerion angustifolium (Onagraceae). Ecol Evol 2019; 9:1095-1109. [PMID: 30805143 PMCID: PMC6374662 DOI: 10.1002/ece3.4797] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 11/16/2018] [Accepted: 11/19/2018] [Indexed: 01/15/2023] Open
Abstract
In many ecosystems, plant growth and reproduction are nitrogen limited. Current and predicted increases of global reactive nitrogen could alter the ecological and evolutionary trajectories of plant populations. Nitrogen is a major component of nucleic acids and cell structures, and it has been predicted that organisms with larger genomes should require more nitrogen for growth and reproduction and be more negatively affected by nitrogen scarcities than organisms with smaller genomes. In a greenhouse experiment, we tested this hypothesis by examining whether the amount of soil nitrogen supplied differentially influenced the performance (fitness, growth, and resource allocation strategies) of diploid and autotetraploid fireweed (Chamerion angustifolium). We found that soil nitrogen levels differentially impacted cytotype performance, and in general, diploids were favored under low nitrogen conditions, but this diploid advantage disappeared under nitrogen enrichment. Specifically, when nitrogen was scarce, diploids produced more seeds and allocated more biomass toward seed production relative to investment in plant biomass or total plant nitrogen than did tetraploids. As nitrogen supplied increased, such discrepancies between cytotypes disappeared. We also found that cytotype resource allocation strategies were differentially dependent on soil nitrogen, and that whereas diploids adopted resource allocation strategies that favored current season reproduction when nitrogen was limiting and future reproduction when nitrogen was more plentiful, tetraploids adopted resource allocation strategies that favored current season reproduction under nitrogen enrichment. Together these results suggest nitrogen enrichment could differentially affect cytotype performance, which could have implications for cytotypes' ecological and evolutionary dynamics under a globally changing climate.
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Affiliation(s)
- Alex L. Bales
- Microbiology DepartmentUniversity of MassachusettsAmherstMassachusetts
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14
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Ganeteg U, Ahmad I, Jämtgård S, Aguetoni-Cambui C, Inselsbacher E, Svennerstam H, Schmidt S, Näsholm T. Amino acid transporter mutants of Arabidopsis provides evidence that a non-mycorrhizal plant acquires organic nitrogen from agricultural soil. PLANT, CELL & ENVIRONMENT 2017; 40:413-423. [PMID: 27943312 DOI: 10.1111/pce.12881] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 11/16/2016] [Accepted: 11/21/2016] [Indexed: 05/03/2023]
Abstract
Although organic nitrogen (N) compounds are ubiquitous in soil solutions, their potential role in plant N nutrition has been questioned. We performed a range of experiments on Arabidopsis thaliana genetically modified to enhance or reduce root uptake of amino acids. Plants lacking expression of the Lysine Histidine Transporter 1 (LHT1) displayed significantly lower contents of 13 C and 15 N label and of U-13 C5 ,15 N2 L-glutamine, as determined by liquid chromatography-mass spectrometry when growing in pots and supplied with dually labelled L-glutamine compared to wild type plants and LHT1-overexpressing plants. Slopes of regressions between accumulation of 13 C-labelled carbon and 15 N-labelled N were higher for LHT1-overexpressing plants than wild type plants, while plants lacking expression of LHT1 did not display a significant regression between the two isotopes. Uptake of labelled organic N from soil tallied with that of labelled ammonium for wild type plants and LHT1-overexpressing plants but was significantly lower for plants lacking expression of LHT1. When grown on agricultural soil plants lacking expression of LHT1 had the lowest, and plants overexpressing LHT1 the highest C/N ratios and natural δ15 N abundance suggesting their dependence on different N pools. Our data show that LHT1 expression is crucial for plant uptake of organic N from soil.
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Affiliation(s)
- Ulrika Ganeteg
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden
| | - Iftikhar Ahmad
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden
| | - Sandra Jämtgård
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden
| | - Camila Aguetoni-Cambui
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden
| | - Erich Inselsbacher
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden
- University of Vienna, Department of Geography and Regional Research, Vienna, AT-1090, Austria
| | - Henrik Svennerstam
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden
| | - Susanne Schmidt
- School of Agriculture and Food Sciences, The University of Queensland, QLD, 4072, Brisbane, Australia
| | - Torgny Näsholm
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden
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15
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Yang L, Zhang L, Yu C, Li D, Gong P, Xue Y, Song Y, Cui Y, Doane TA, Wu Z. Nitrogen Fertilizer and Straw Applications Affect Uptake of 13C,15N-Glycine by Soil Microorganisms in Wheat Growth Stages. PLoS One 2017; 12:e0169016. [PMID: 28045989 PMCID: PMC5207700 DOI: 10.1371/journal.pone.0169016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 12/09/2016] [Indexed: 11/19/2022] Open
Abstract
This study investigated the influence of nitrogen (N) fertilizer and straw on intact amino acid N uptake by soil microorganisms and the relationship between amino acid turnover and soil properties during the wheat growing season. A wheat pot experiment was carried out with three treatments: control (CK), N fertilizer (NF) and N fertilizer plus rice straw (NS). We used stable isotope compound-specific analysis to determine the uptake of 13C,15N-glycine by soil microorganisms. In the NF treatment, microbial 13C,15N-glycine uptake was lower compared with CK, suggesting that inorganic N was the preferred N source for soil microorganisms. However, The application of straw with N fertilizer (in NS treatment) increased microbial 13C,15N-glycine uptake even with the same amount of N fertilizer application. In this treatment, enzyme activities, soil microbial biomass C and microbial biomass N increased simultaneously because more C was available. Soil mineral N and plant N contents all decreased substantially. The increased uptake of intact 13C,15N-glycine in the NS treatment can be attributed to direct assimilation by soil microorganisms to satisfy the demand for N when inorganic N was consumed.
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Affiliation(s)
- Lijie Yang
- National Nutrition and Engineering Lab, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang Liaoning, China
- Graduate School, University of Chinese Academy of Sciences, Beijing, China
| | - Lili Zhang
- National Nutrition and Engineering Lab, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang Liaoning, China
- * E-mail: (LZ); (ZW)
| | - Chunxiao Yu
- National Nutrition and Engineering Lab, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang Liaoning, China
- Graduate School, University of Chinese Academy of Sciences, Beijing, China
| | - Dongpo Li
- National Nutrition and Engineering Lab, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang Liaoning, China
| | - Ping Gong
- National Nutrition and Engineering Lab, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang Liaoning, China
| | - Yan Xue
- National Nutrition and Engineering Lab, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang Liaoning, China
| | - Yuchao Song
- National Nutrition and Engineering Lab, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang Liaoning, China
| | - Yalan Cui
- National Nutrition and Engineering Lab, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang Liaoning, China
- Graduate School, University of Chinese Academy of Sciences, Beijing, China
| | - Timothy A. Doane
- Department of Land, Air, and Water Resources, University of California Davis, Davis California, United States of America
| | - Zhijie Wu
- National Nutrition and Engineering Lab, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang Liaoning, China
- * E-mail: (LZ); (ZW)
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16
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Cao X, Ma Q, Zhong C, Yang X, Zhu L, Zhang J, Jin Q, Wu L. Elevational Variation in Soil Amino Acid and Inorganic Nitrogen Concentrations in Taibai Mountain, China. PLoS One 2016; 11:e0157979. [PMID: 27337100 PMCID: PMC4918969 DOI: 10.1371/journal.pone.0157979] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 06/08/2016] [Indexed: 11/18/2022] Open
Abstract
Amino acids are important sources of soil organic nitrogen (N), which is essential for plant nutrition, but detailed information about which amino acids predominant and whether amino acid composition varies with elevation is lacking. In this study, we hypothesized that the concentrations of amino acids in soil would increase and their composition would vary along the elevational gradient of Taibai Mountain, as plant-derived organic matter accumulated and N mineralization and microbial immobilization of amino acids slowed with reduced soil temperature. Results showed that the concentrations of soil extractable total N, extractable organic N and amino acids significantly increased with elevation due to the accumulation of soil organic matter and the greater N content. Soil extractable organic N concentration was significantly greater than that of the extractable inorganic N (NO3--N + NH4+-N). On average, soil adsorbed amino acid concentration was approximately 5-fold greater than that of the free amino acids, which indicates that adsorbed amino acids extracted with the strong salt solution likely represent a potential source for the replenishment of free amino acids. We found no appreciable evidence to suggest that amino acids with simple molecular structure were dominant at low elevations, whereas amino acids with high molecular weight and complex aromatic structure dominated the high elevations. Across the elevational gradient, the amino acid pool was dominated by alanine, aspartic acid, glycine, glutamic acid, histidine, serine and threonine. These seven amino acids accounted for approximately 68.9% of the total hydrolyzable amino acid pool. The proportions of isoleucine, tyrosine and methionine varied with elevation, while soil major amino acid composition (including alanine, arginine, aspartic acid, glycine, histidine, leucine, phenylalanine, serine, threonine and valine) did not vary appreciably with elevation (p>0.10). The compositional similarity of many amino acids across the elevational gradient suggests that soil amino acids likely originate from a common source or through similar biochemical processes.
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Affiliation(s)
- Xiaochuang Cao
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006 China
| | - Qingxu Ma
- Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058 China
| | - Chu Zhong
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006 China
| | - Xin Yang
- Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058 China
| | - Lianfeng Zhu
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006 China
| | - Junhua Zhang
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006 China
| | - Qianyu Jin
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006 China
| | - Lianghuan Wu
- Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058 China
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Sponseller RA, Gundale MJ, Futter M, Ring E, Nordin A, Näsholm T, Laudon H. Nitrogen dynamics in managed boreal forests: Recent advances and future research directions. AMBIO 2016; 45 Suppl 2:175-87. [PMID: 26744052 PMCID: PMC4705067 DOI: 10.1007/s13280-015-0755-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Nitrogen (N) availability plays multiple roles in the boreal landscape, as a limiting nutrient to forest growth, determinant of terrestrial biodiversity, and agent of eutrophication in aquatic ecosystems. We review existing research on forest N dynamics in northern landscapes and address the effects of management and environmental change on internal cycling and export. Current research foci include resolving the nutritional importance of different N forms to trees and establishing how tree-mycorrhizal relationships influence N limitation. In addition, understanding how forest responses to external N inputs are mediated by above- and belowground ecosystem compartments remains an important challenge. Finally, forestry generates a mosaic of successional patches in managed forest landscapes, with differing levels of N input, biological demand, and hydrological loss. The balance among these processes influences the temporal patterns of stream water chemistry and the long-term viability of forest growth. Ultimately, managing forests to keep pace with increasing demands for biomass production, while minimizing environmental degradation, will require multi-scale and interdisciplinary perspectives on landscape N dynamics.
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Affiliation(s)
- Ryan A Sponseller
- Department of Ecology and Environmental Science, Umeå University, 901 87, Umeå, Sweden.
| | - Michael J Gundale
- Department of Forest Ecology and Mangement, SLU, Skogsmarksgränd, 901 83, Umeå, Sweden.
| | - Martyn Futter
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, 750 07, Uppsala, Sweden.
| | - Eva Ring
- Skogforsk, Uppsala Science Park, 751 83, Uppsala, Sweden.
| | - Annika Nordin
- Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83, Umeå, Sweden.
| | - Torgny Näsholm
- Department of Forest Ecology and Mangement, SLU, Skogsmarksgränd, 901 83, Umeå, Sweden.
| | - Hjalmar Laudon
- Department of Forest Ecology and Mangement, SLU, Skogsmarksgränd, 901 83, Umeå, Sweden.
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18
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Brackin R, Näsholm T, Robinson N, Guillou S, Vinall K, Lakshmanan P, Schmidt S, Inselsbacher E. Nitrogen fluxes at the root-soil interface show a mismatch of nitrogen fertilizer supply and sugarcane root uptake capacity. Sci Rep 2015; 5:15727. [PMID: 26496834 PMCID: PMC4620560 DOI: 10.1038/srep15727] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 10/01/2015] [Indexed: 01/26/2023] Open
Abstract
Globally only ≈50% of applied nitrogen (N) fertilizer is captured by crops, and the remainder can cause pollution via runoff and gaseous emissions. Synchronizing soil N supply and crop demand will address this problem, however current soil analysis methods provide little insight into delivery and acquisition of N forms by roots. We used microdialysis, a novel technique for in situ quantification of soil nutrient fluxes, to measure N fluxes in sugarcane cropping soils receiving different fertilizer regimes, and compare these with N uptake capacities of sugarcane roots. We show that in fertilized sugarcane soils, fluxes of inorganic N exceed the uptake capacities of sugarcane roots by several orders of magnitude. Contrary, fluxes of organic N closely matched roots' uptake capacity. These results indicate root uptake capacity constrains plant acquisition of inorganic N. This mismatch between soil N supply and root N uptake capacity is a likely key driver for low N efficiency in the studied crop system. Our results also suggest that (i) the relative contribution of inorganic N for plant nutrition may be overestimated when relying on soil extracts as indicators for root-available N, and (ii) organic N may contribute more to crop N supply than is currently assumed.
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Affiliation(s)
- Richard Brackin
- School of Agriculture and Food Sciences, The University of Queensland, QLD, 4072, Australia
| | - Torgny Näsholm
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Center, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
| | - Nicole Robinson
- School of Agriculture and Food Sciences, The University of Queensland, QLD, 4072, Australia
| | - Stéphane Guillou
- School of Agriculture and Food Sciences, The University of Queensland, QLD, 4072, Australia
| | - Kerry Vinall
- School of Agriculture and Food Sciences, The University of Queensland, QLD, 4072, Australia
| | - Prakash Lakshmanan
- Sugar Research Australia, 50 Meiers Road, Indooroopilly, QLD 4068, Australia
| | - Susanne Schmidt
- School of Agriculture and Food Sciences, The University of Queensland, QLD, 4072, Australia
| | - Erich Inselsbacher
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
- University of Vienna, Department of Geography and Regional Research, Vienna, AT-1090, Austria
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Fate of the insecticidal Cry1Ab protein of GM crops in two agricultural soils as revealed by ¹⁴C-tracer studies. Appl Microbiol Biotechnol 2015; 99:7333-41. [PMID: 25967657 DOI: 10.1007/s00253-015-6655-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 04/24/2015] [Accepted: 04/27/2015] [Indexed: 10/23/2022]
Abstract
Insecticidal delta-endotoxins of Bacillus thuringiensis are among the most abundant recombinant proteins released by genetically modified (GM) crops into agricultural soils worldwide. However, there is still controversy about their degradation and accumulation in soils. In this study, (14)C-labelled Cry1Ab protein was applied to soil microcosms at two concentrations (14 and 50 μg g(-1) soil) to quantify the mineralization of Cry1Ab, its incorporation into the soil microbial biomass, and its persistence in two soils which strongly differed in their texture but not in silt or pH. Furthermore, ELISA was used to quantify Cry1Ab and its potential immunoreactive breakdown products in aqueous soil extracts. In both soils, (14)CO2-production was initially very high and then declined during a total monitoring period of up to 135 days. A total of 16 to 23 % of the (14)C activity was incorporated after 29 to 37 days into the soil microbial biomass, indicating that Cry1Ab protein was utilized by microorganisms as a growth substrate. Adsorption in the clay-rich soil was the most important factor limiting microbial degradation; as indicated by higher degradation rates in the more sandy soil, extremely low concentrations of immunoreactive Cry1Ab molecules in the soils' aqueous extracts and a higher amount of (14)C activity bound to the soil with more clay. Ecological risk assessments of Bt-crops should therefore consider that the very low concentrations of extractable Cry1Ab do not reflect the actual elimination of the protein from soils but that, on the other hand, desorbed proteins mineralize quickly due to efficient microbial degradation.
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Wild B, Schnecker J, Knoltsch A, Takriti M, Mooshammer M, Gentsch N, Mikutta R, Alves RJE, Gittel A, Lashchinskiy N, Richter A. Microbial nitrogen dynamics in organic and mineral soil horizons along a latitudinal transect in western Siberia. GLOBAL BIOGEOCHEMICAL CYCLES 2015; 29:567-582. [PMID: 26693204 PMCID: PMC4676305 DOI: 10.1002/2015gb005084] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 04/09/2015] [Accepted: 04/01/2015] [Indexed: 05/22/2023]
Abstract
Soil N availability is constrained by the breakdown of N-containing polymers such as proteins to oligopeptides and amino acids that can be taken up by plants and microorganisms. Excess N is released from microbial cells as ammonium (N mineralization), which in turn can serve as substrate for nitrification. According to stoichiometric theory, N mineralization and nitrification are expected to increase in relation to protein depolymerization with decreasing N limitation, and thus from higher to lower latitudes and from topsoils to subsoils. To test these hypotheses, we compared gross rates of protein depolymerization, N mineralization and nitrification (determined using 15N pool dilution assays) in organic topsoil, mineral topsoil, and mineral subsoil of seven ecosystems along a latitudinal transect in western Siberia, from tundra (67°N) to steppe (54°N). The investigated ecosystems differed strongly in N transformation rates, with highest protein depolymerization and N mineralization rates in middle and southern taiga. All N transformation rates decreased with soil depth following the decrease in organic matter content. Related to protein depolymerization, N mineralization and nitrification were significantly higher in mineral than in organic horizons, supporting a decrease in microbial N limitation with depth. In contrast, we did not find indications for a decrease in microbial N limitation from arctic to temperate ecosystems along the transect. Our findings thus challenge the perception of ubiquitous N limitation at high latitudes, but suggest a transition from N to C limitation of microorganisms with soil depth, even in high-latitude systems such as tundra and boreal forest. KEY POINTS We compared soil N dynamics of seven ecosystems along a latitudinal transectShifts in N dynamics suggest a decrease in microbial N limitation with depthWe found no decrease in microbial N limitation from arctic to temperate zones.
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Affiliation(s)
- Birgit Wild
- Department of Microbiology and Ecosystem Science, University of Vienna Vienna, Austria ; Austrian Polar Research Institute Vienna, Austria ; Department of Earth Sciences, University of Gothenburg Gothenburg, Sweden
| | - Jörg Schnecker
- Department of Microbiology and Ecosystem Science, University of Vienna Vienna, Austria ; Austrian Polar Research Institute Vienna, Austria
| | - Anna Knoltsch
- Department of Microbiology and Ecosystem Science, University of Vienna Vienna, Austria ; Austrian Polar Research Institute Vienna, Austria
| | - Mounir Takriti
- Department of Microbiology and Ecosystem Science, University of Vienna Vienna, Austria ; Austrian Polar Research Institute Vienna, Austria
| | - Maria Mooshammer
- Department of Microbiology and Ecosystem Science, University of Vienna Vienna, Austria
| | - Norman Gentsch
- Institute of Soil Science, Leibniz Universität Hannover Hannover, Germany
| | - Robert Mikutta
- Institute of Soil Science, Leibniz Universität Hannover Hannover, Germany
| | - Ricardo J Eloy Alves
- Austrian Polar Research Institute Vienna, Austria ; Department of Ecogenomics and Systems Biology, University of Vienna Vienna, Austria
| | - Antje Gittel
- Department of Biology, Centre for Geobiology, University of Bergen Bergen, Norway ; Department of Bioscience, Center for Geomicrobiology Aarhus, Denmark
| | - Nikolay Lashchinskiy
- Central Siberian Botanical Garden, Siberian Branch of Russian Academy of Sciences Novosibirsk, Russia
| | - Andreas Richter
- Department of Microbiology and Ecosystem Science, University of Vienna Vienna, Austria ; Austrian Polar Research Institute Vienna, Austria
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21
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Mooshammer M, Wanek W, Hämmerle I, Fuchslueger L, Hofhansl F, Knoltsch A, Schnecker J, Takriti M, Watzka M, Wild B, Keiblinger KM, Zechmeister-Boltenstern S, Richter A. Adjustment of microbial nitrogen use efficiency to carbon:nitrogen imbalances regulates soil nitrogen cycling. Nat Commun 2014; 5:3694. [PMID: 24739236 PMCID: PMC3997803 DOI: 10.1038/ncomms4694] [Citation(s) in RCA: 201] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 03/20/2014] [Indexed: 11/25/2022] Open
Abstract
Microbial nitrogen use efficiency (NUE) describes the partitioning of organic N taken up between growth and the release of inorganic N to the environment (that is, N mineralization), and is thus central to our understanding of N cycling. Here we report empirical evidence that microbial decomposer communities in soil and plant litter regulate their NUE. We find that microbes retain most immobilized organic N (high NUE), when they are N limited, resulting in low N mineralization. However, when the metabolic control of microbial decomposers switches from N to C limitation, they release an increasing fraction of organic N as ammonium (low NUE). We conclude that the regulation of NUE is an essential strategy of microbial communities to cope with resource imbalances, independent of the regulation of microbial carbon use efficiency, with significant effects on terrestrial N cycling. Nitrogen availability in soils is predominantly controlled by microorganisms, yet our understanding of their organic nitrogen use is limited. Mooshammer et al. show that microbial nitrogen use efficiency is dependent on resource stoichiometry and substrate type.
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Affiliation(s)
- Maria Mooshammer
- Department of Microbiology and Ecosystem Science, Terrestrial Ecosystem Research, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Wolfgang Wanek
- Department of Microbiology and Ecosystem Science, Terrestrial Ecosystem Research, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Ieda Hämmerle
- Department of Microbiology and Ecosystem Science, Terrestrial Ecosystem Research, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Lucia Fuchslueger
- Department of Microbiology and Ecosystem Science, Terrestrial Ecosystem Research, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Florian Hofhansl
- Department of Microbiology and Ecosystem Science, Terrestrial Ecosystem Research, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Anna Knoltsch
- Department of Microbiology and Ecosystem Science, Terrestrial Ecosystem Research, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Jörg Schnecker
- Department of Microbiology and Ecosystem Science, Terrestrial Ecosystem Research, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Mounir Takriti
- Department of Microbiology and Ecosystem Science, Terrestrial Ecosystem Research, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Margarete Watzka
- Department of Microbiology and Ecosystem Science, Terrestrial Ecosystem Research, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Birgit Wild
- Department of Microbiology and Ecosystem Science, Terrestrial Ecosystem Research, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Katharina M Keiblinger
- Department of Forest and Soil Sciences, Institute of Soil Research, University of Natural Resources and Life Sciences, Peter-Jordan-Strasse 82, 1190 Vienna, Austria
| | - Sophie Zechmeister-Boltenstern
- Department of Forest and Soil Sciences, Institute of Soil Research, University of Natural Resources and Life Sciences, Peter-Jordan-Strasse 82, 1190 Vienna, Austria
| | - Andreas Richter
- Department of Microbiology and Ecosystem Science, Terrestrial Ecosystem Research, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
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Gruffman L, Jämtgård S, Näsholm T. Plant nitrogen status and co-occurrence of organic and inorganic nitrogen sources influence root uptake by Scots pine seedlings. TREE PHYSIOLOGY 2014; 34:205-13. [PMID: 24488801 DOI: 10.1093/treephys/tpt121] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Insights into how the simultaneous presence of organic and inorganic nitrogen (N) forms influences root absorption will help elucidate the relative importance of these N forms for plant nutrition in the field as well as for nursery cultivation of seedlings. Uptake of the individual N forms arginine, ammonium (NH4(+)) and nitrate (NO3(-)) was studied in Scots pine (Pinus sylvestris (L.)) seedlings supplied as single N sources and additionally in mixtures of NO3(-) and NH4(+) or NO3(-) and arginine. Scots pine seedlings displayed a strong preference for NH4(+)-N and arginine-N as compared with NO3(-)-N. Thus, NO3(-) uptake was generally low and decreased in the presence of NH4(+) in the high-concentration range (500 µM N), but not in the presence of arginine. Moreover, uptake of NO3(-) and NH4(+) was lower in seedlings displaying a high internal N status as a result of high N pre-treatment, while arginine uptake was high in seedlings with a high internal N status when previously exposed to organic N. These findings may have practical implications for commercial cultivation of conifers.
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Affiliation(s)
- Linda Gruffman
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
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Abstract
Often referred to as the "building blocks of proteins", the 20 canonical proteinogenic amino acids are ubiquitous in biological systems as the functional units in proteins. Sometimes overlooked are their varying additional roles that include serving as metabolic intermediaries, playing structural roles in bioactive natural products, acting as cosubstrates in enzymatic transformations, and as key regulators of cellular physiology. Amino acids can also serve as biological sources of both carbon and nitrogen and are found in the rhizosphere as a result of lysis or cellular efflux from plants and microbes and proteolysis of existing peptides. While both plants and microbes apparently prefer to take up nitrogen in its inorganic form, their ability to take up and use amino acids may confer a selective advantage in certain environments where organic nitrogen is abundant. Further, certain amino acids (e.g., glutamate and proline) and their betaines (e.g., glycine betaine) serve as compatible solutes necessary for osmoregulation in plants and microbes and can undergo rapid cellular flux. This ability is of particular importance in an ecological niche such as the rhizosphere, which is prone to significant variations in solute concentrations. Amino acids are also shown to alter key phenotypes related to plant root growth and microbial colonization, symbiotic interactions, and pathogenesis in the rhizosphere. This review will focus on the sources, transport mechanisms, and potential roles of the 20 canonical proteinogenic amino acids in the rhizosphere.
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Affiliation(s)
- Luke A Moe
- Department of Plant & Soil Sciences, 311 Plant Science Building, University of Kentucky, Lexington, Kentucky 40546-0312, USA
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Chen XY, Wu LH, Cao XC, Zhu YH. Organic nitrogen components in soils from southeast China. J Zhejiang Univ Sci B 2013; 14:259-69. [PMID: 23549843 PMCID: PMC3625522 DOI: 10.1631/jzus.b1200104] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Accepted: 11/11/2012] [Indexed: 11/11/2022]
Abstract
OBJECTIVE To investigate the amounts of extractable organic nitrogen (EON), and the relationships between EON and total extractable nitrogen (TEN), especially the amino acids (AAs) adsorbed by soils, and a series of other hydrolyzed soil nitrogen indices in typical land use soil types from southeast China. Under traditional agricultural planting conditions, the functions of EON, especially AAs in the rhizosphere and in bulk soil zones were also investigated. METHODS Pot experiments were conducted using plants of pakchoi (Brassica chinensis L.) and rice (Oryza sativa L.). In the rhizosphere and bulk soil zone studies, organic nitrogen components were extracted with either distilled water, 0.5 mol/L K2SO4 or acid hydrolysis. RESULTS K2SO4-EON constituted more than 30% of TEN pools. K2SO4-extractable AAs accounted for 25% of EON pools and nearly 10% of TEN pools in rhizosphere soils. Overall, both K2SO4-EON and extractable AAs contents had positive correlations with TEN pools. CONCLUSIONS EON represented a major component of TEN pools in garden and paddy soils under traditional planting conditions. Although only a small proportion of the EON was present in the form of water-extractable and K2SO4-extractable AAs, the release of AAs from soil exchangeable sites might be an important source of organic nitrogen (N) for plant growth. Our findings suggest that the content of most organic forms of N was significantly greater in rhizosphere than in bulk soil zone samples. However, it was also apparent that the TEN pool content was lower in rhizosphere than in bulk soil samples without added N.
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Affiliation(s)
- Xian-you Chen
- Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory of Subtropical Soil and Plant Nutrition, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Liang-huan Wu
- Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory of Subtropical Soil and Plant Nutrition, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Xiao-chuang Cao
- Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory of Subtropical Soil and Plant Nutrition, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yuan-hong Zhu
- Department of Crop and Soil Sciences, the Pennsylvania State University, University Park, Pennsylvania PA 16802, USA
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25
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Artz RRE. Microbial Community Structure and Carbon Substrate use in Northern Peatlands. CARBON CYCLING IN NORTHERN PEATLANDS 2013. [DOI: 10.1029/2008gm000806] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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26
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Farrell M, Hill PW, Farrar J, DeLuca TH, Roberts P, Kielland K, Dahlgren R, Murphy DV, Hobbs PJ, Bardgett RD, Jones DL. Oligopeptides Represent a Preferred Source of Organic N Uptake: A Global Phenomenon? Ecosystems 2012. [DOI: 10.1007/s10021-012-9601-8] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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27
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Harms TK, Jones JB. Thaw depth determines reaction and transport of inorganic nitrogen in valley bottom permafrost soils: Nitrogen cycling in permafrost soils. GLOBAL CHANGE BIOLOGY 2012; 18:2958-2968. [PMID: 24501070 DOI: 10.1111/j.1365-2486.2012.02731.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 04/23/2012] [Accepted: 04/26/2012] [Indexed: 06/03/2023]
Abstract
Nitrate (NO3 (-) ) export coupled with high inorganic nitrogen (N) concentrations in Alaskan streams suggests that N cycles of permafrost-influenced ecosystems are more open than expected for N-limited ecosystems. We tested the hypothesis that soil thaw depth governs inorganic N retention and removal in soils due to vertical patterns in the dominant N transformation pathways. Using an in situ, push-pull method, we estimated rates of inorganic N uptake and denitrification during snow melt, summer, and autumn, as depth of soil-stream flowpaths increased in the valley bottom of an arctic and a boreal catchment. Net NO3 (-) uptake declined sharply from snow melt to summer and decreased as a nonlinear function of thaw depth. Peak denitrification rate occurred during snow melt at the arctic site, in summer at the boreal site, and declined as a nonlinear function of thaw depth across both sites. Seasonal patterns in ammonium (NH4 (+) ) uptake were not significant, but low rates during the peak growing season suggest uptake that is balanced by mineralization. Despite rapid rates of hydrologic transport during snow melt runoff, rates of uptake and removal of inorganic N tended to exceed water residence time during snow melt, indicating potential for retention of N in valley bottom soils when flowpaths are shallow. Decreased reaction rates relative to water residence time in subsequent seasons suggest greater export of inorganic N as the soil-stream flowpath deepens due to thawing soils. Using seasonal thaw as a proxy for longer term deepening of the thaw layer caused by climate warming and permafrost degradation, these results suggest increasing potential for export of inorganic N from permafrost-influenced soils to streams.
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Affiliation(s)
- Tamara K Harms
- Institute of Arctic Biology, University of Alaska-Fairbanks, 99775, Alaska, USA
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28
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Inselsbacher E, Näsholm T. The below-ground perspective of forest plants: soil provides mainly organic nitrogen for plants and mycorrhizal fungi. THE NEW PHYTOLOGIST 2012; 195:329-334. [PMID: 22564239 DOI: 10.1111/j.1469-8137.2012.04169.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
• Nitrogen (N) availability has a major impact on a wide range of biogeochemical processes in terrestrial ecosystems. Changes in N availability modify the capacity of plants to sequester carbon (C), but despite the crucial importance for our understanding of terrestrial ecosystems, the relative contribution of different N forms to plant N nutrition in the field is not known. Until now, reliably assessing the highly dynamic pool of plant-available N in soil microsites was virtually impossible, because of the lack of adequate sampling techniques. • For the first time we have applied a novel microdialysis technique for disturbance-free monitoring of diffusive fluxes of inorganic and organic N in 15 contrasting boreal forest soils in situ. • We found that amino acids accounted for 80% of the soil N supply, while ammonium and nitrate contributed only 10% each. In contrast to common soil extractions, microdialysis revealed that the majority of amino acids are available for plant and mycorrhizal uptake. • Our results suggest that the N supply of boreal forest soils is dominated by organic N as a major component of plant-available N and thus as a regulator of growth and C sequestration.
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Affiliation(s)
- Erich Inselsbacher
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
| | - Torgny Näsholm
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Center, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
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29
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Nitrogen Isotope Patterns in Alaskan Black Spruce Reflect Organic Nitrogen Sources and the Activity of Ectomycorrhizal Fungi. Ecosystems 2012. [DOI: 10.1007/s10021-012-9548-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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30
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Wu H, Dannenmann M, Wolf B, Han XG, Zheng X, Butterbach-Bahl K. Seasonality of soil microbial nitrogen turnover in continental steppe soils of Inner Mongolia. Ecosphere 2012. [DOI: 10.1890/es11-00188.1] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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31
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Govind A, Chen JM, Bernier P, Margolis H, Guindon L, Beaudoin A. Spatially distributed modeling of the long-term carbon balance of a boreal landscape. Ecol Modell 2011. [DOI: 10.1016/j.ecolmodel.2011.04.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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32
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Averill C, Finzi A. Increasing plant use of organic nitrogen with elevation is reflected in nitrogen uptake rates and ecosystem δ15N. Ecology 2011; 92:883-91. [DOI: 10.1890/10-0746.1] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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33
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Amino acid abundance and proteolytic potential in North American soils. Oecologia 2010; 163:1069-78. [DOI: 10.1007/s00442-010-1601-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Accepted: 03/02/2010] [Indexed: 10/19/2022]
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34
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LeDuc SD, Rothstein DE. Plant-available organic and mineral nitrogen shift in dominance with forest stand age. Ecology 2010; 91:708-20. [DOI: 10.1890/09-0140.1] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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35
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McFarland JW, Ruess RW, Kielland K, Pregitzer K, Hendrick R, Allen M. Cross-Ecosystem Comparisons of In Situ Plant Uptake of Amino Acid-N and NH4 +. Ecosystems 2010. [DOI: 10.1007/s10021-009-9309-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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36
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Rennenberg H, Dannenmann M, Gessler A, Kreuzwieser J, Simon J, Papen H. Nitrogen balance in forest soils: nutritional limitation of plants under climate change stresses. PLANT BIOLOGY (STUTTGART, GERMANY) 2009; 11 Suppl 1:4-23. [PMID: 19778364 DOI: 10.1111/j.1438-8677.2009.00241.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Forest ecosystems with low soil nitrogen (N) availability are characterized by direct competition for this growth-limiting resource between several players, i.e. various components of vegetation, such as old-growth trees, natural regeneration and understorey species, mycorrhizal fungi, free-living fungi and bacteria. With the increase in frequency and intensity of extreme climate events predicted in current climate change scenarios, also competition for N between plants and/or soil microorganisms will be affected. In this review, we summarize the present understanding of ecosystem N cycling in N-limited forests and its interaction with extreme climate events, such as heat, drought and flooding. More specifically, the impacts of environmental stresses on microbial release and consumption of bioavailable N, N uptake and competition between plants, as well as plant and microbial uptake are presented. Furthermore, the consequences of drying-wetting cycles on N cycling are discussed. Additionally, we highlight the current methodological difficulties that limit present understanding of N cycling in forest ecosystems and the need for interdisciplinary studies.
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Affiliation(s)
- H Rennenberg
- Chair of Tree Physiology, Institute of Forest Botany and Tree Physiology, University of Freiburg, Freiburg, Germany
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37
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Abstract
Languishing for many years in the shadow of plant inorganic nitrogen (N) nutrition research, studies of organic N uptake have attracted increased attention during the last decade. The capacity of plants to acquire organic N, demonstrated in laboratory and field settings, has thereby been well established. Even so, the ecological significance of organic N uptake for plant N nutrition is still a matter of discussion. Several lines of evidence suggest that plants growing in various ecosystems may access organic N species. Many soils display amino acid concentrations similar to, or higher than, those of inorganic N, mainly as a result of rapid hydrolysis of soil proteins. Transporters mediating amino acid uptake have been identified both in mycorrhizal fungi and in plant roots. Studies of endogenous metabolism of absorbed amino acids suggest that L- but not D-enantiomers are efficiently utilized. Dual labelled amino acids supplied to soil have provided strong evidence for plant uptake of organic N in the field but have failed to provide information on the quantitative importance of this process. Thus, direct evidence that organic N contributes significantly to plant N nutrition is still lacking. Recent progress in our understanding of the mechanisms underlying plant organic N uptake may open new avenues for the exploration of this subject.
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Affiliation(s)
- Torgny Näsholm
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
| | - Knut Kielland
- Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775-0180, USA
| | - Ulrika Ganeteg
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
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Forsum O, Svennerstam H, Ganeteg U, Näsholm T. Capacities and constraints of amino acid utilization in Arabidopsis. THE NEW PHYTOLOGIST 2008; 179:1058-1069. [PMID: 18627491 DOI: 10.1111/j.1469-8137.2008.02546.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Various amino acids, including both L- and D-enantiomers, may be present in soils, and recent studies have indicated that plants may access such nitrogen (N) forms. Here, the capacity of Arabidopsis to utilize different L- and D-amino acids is investigated and the constraints on this process are explored. Mutants defective in the lysine histidine transporter 1 (LHT1) and transgenic plants overexpressing LHT1 as well as plants expressing D-amino acid-metabolizing enzymes, were used in studies of uptake and growth on various N forms. Arabidopsis absorbed all tested N-forms, but D-enantiomers at lower rates than L-forms. Several L- but no D-forms were effective as N sources. Plants deficient in LHT1 displayed strong growth reductions and plants overexpressing LHT1 showed strong growth enhancement when N was supplied as amino acids, in particular when these were supplied at low concentrations. Several D- amino acids inhibited growth of wild-type plants, while transgenic Arabidopsis-expressing genes encoding D-amino acid-metabolizing enzymes could efficiently utilize such compounds for growth. These results suggest that several amino acids, and in particular L-Gln and L-Asn, promote growth of Arabidopsis, and increased expression of specific amino acid transporters enhances growth on amino acids. The efficiency by which transgenic plants exploit D-amino acids illustrates how plants can be engineered to utilize specific N sources otherwise inaccessible to them.
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Affiliation(s)
- Oskar Forsum
- Umeå Plant Science Centre, Department or Forest Genetics and Plant Physiology and
| | - Henrik Svennerstam
- Umeå Plant Science Centre, Department or Forest Genetics and Plant Physiology and
| | - Ulrika Ganeteg
- Umeå Plant Science Centre, Department or Forest Genetics and Plant Physiology and
| | - Torgny Näsholm
- Umeå Plant Science Centre, Department or Forest Genetics and Plant Physiology and
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
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