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Han E, Kopf SH, Maloney AE, Ai XE, Sigman DM, Zhang X. Nitrogen stable isotope fractionation by biological nitrogen fixation reveals cellular nitrogenase is diffusion limited. PNAS NEXUS 2025; 4:pgaf061. [PMID: 40099223 PMCID: PMC11913218 DOI: 10.1093/pnasnexus/pgaf061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2024] [Accepted: 01/21/2025] [Indexed: 03/19/2025]
Abstract
Biological fixation of dinitrogen (N2), the primary natural source of new bioavailable nitrogen (N) on Earth, is catalyzed by the enzyme nitrogenase through a complex mechanism at its active site metal cofactor. How this reaction functions in cellular environments, including its rate-limiting step, and how enzyme structure affects functioning remain unclear. Here, we investigated cellular N2 fixation through its N isotope effect (15εfix), measured as the difference between the 15N/14N ratios of diazotroph net new fixed N and N2 substrate. The value of 15εfix underpins N cycle reconstructions and differs between diazotrophs using molybdenum-containing and molybdenum-free nitrogenases. By examining 15εfix for Azotobacter vinelandii strains with natural and mutated nitrogenases, we determined if 15εfix reflects enzyme-scale isotope effects and, thus, N2 use efficiency. Distinct and relatively stable 15εfix values for wild-type molybdenum- and vanadium-nitrogenase isoforms (2.5‰ and 5.8-6.6‰, respectively), despite changing cellular growth rate and electron availability, support 15εfix as a proxy for isoform type among extant nitrogenases. Structural mutation of active site N2 access altered molybdenum-nitrogenase 15εfix (3.0-6.8‰ for α-70VI mutant). Structure-function and isotopic modeling results indicated cellular N2 reduction is rate-limited by N2 diffusion inside nitrogenase due to highly efficient catalysis by the active site cofactor, exemplifying 15εfix as a tool to probe N2 fixation mechanisms. Diffusion-constrained reactions could reflect structural tradeoffs that protect the oxygen-sensitive cofactor from oxygen inactivation. This suggests that nitrogenase function is optimized for modern oxygenated environments and that pre-Great Oxidative Event nitrogenases were less diffusion-limited and potentially exhibited larger 15εfix values.
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Affiliation(s)
- Eunah Han
- Department of Geosciences, Guyot Hall, Princeton University, Princeton, NJ 08544, USA
| | - Sebastian H Kopf
- Department of Geological Sciences, UCB 399, University of Colorado, Boulder, CO 80309, USA
| | - Ashley E Maloney
- Department of Geosciences, Guyot Hall, Princeton University, Princeton, NJ 08544, USA
| | - Xuyuan Ellen Ai
- Department of Geosciences, Guyot Hall, Princeton University, Princeton, NJ 08544, USA
| | - Daniel M Sigman
- Department of Geosciences, Guyot Hall, Princeton University, Princeton, NJ 08544, USA
| | - Xinning Zhang
- Department of Geosciences, Guyot Hall, Princeton University, Princeton, NJ 08544, USA
- High Meadows Environmental Institute, Guyot Hall, Princeton University, Princeton, NJ 08544, USA
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Yannelli FA, Keet JH, Kritzinger-Klopper S, Le Roux JJ. Legacy effects of an invasive legume more strongly impact bacterial than plant communities in a Mediterranean-type ecosystem. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2025; 373:123802. [PMID: 39729714 DOI: 10.1016/j.jenvman.2024.123802] [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: 07/26/2024] [Revised: 12/16/2024] [Accepted: 12/17/2024] [Indexed: 12/29/2024]
Abstract
The impacts of invasive plants on ecosystem processes and functions may persist as "legacy effects" after their removal. Understanding these effects on native plant-soil interactions is critical for guiding ecological restoration efforts. This study examines the legacy effects of the invasive legume Acacia saligna (Labill.) H.L. Wendl. in South Africa's Cape Fynbos to evaluate restoration potential post-removal. We compared cleared, invaded, and uninvaded reference sites across three conservation areas, examining soil chemical properties, nitrogen (N) isotope signatures (as a proxy for the sources of N uptake by a native plant and A. saligna), and the diversity and composition of plant and soil bacterial communities. The effects of A. saligna removal was contingent on conservation area, though consistent patterns emerged for plant and bacterial diversity across sites. Recovery toward reference site levels were evident for soil organic carbon and potassium, but nitrate and available phosphorous only improved in one area. Invader removal was linked to higher soil pH in one area and higher phosphorus availability in two. Soil conditions in cleared sites influenced the nitrogen sources used by A. saligna, shifting towards soil-derived nitrogen, but did not influence those used by the native species assessed. While we observed signs of native plant community recovery after clearing, soil bacterial communities remained comparable to those in invaded sites. The lag in bacterial community recovery was linked to soil pH changes caused by A. saligna invasion. Our findings demonstrate that removing A. saligna can promote native vegetation recovery, though legacy effects may impede or delay the recovery of soil bacterial communities. The influence of these soil legacy effects may also depend on the management or invasion history of sites.
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Affiliation(s)
- Florencia A Yannelli
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Matieland, 7602, South Africa; Freie Universität Berlin, Department of Biology, Chemistry, Pharmacy, Institute of Biology, 14195, Berlin, Germany; Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), 12587, Berlin, Germany; Argentine Institute for Dryland Research, CONICET and Universidad Nacional de Cuyo, 5500, Mendoza, Argentina.
| | - Jan-Hendrik Keet
- EcoFloristix Specialist Environmental Consulting, Somerset West, 7130, South Africa; Department of Mathematical Sciences, Stellenbosch University, Matieland, 7602, South Africa
| | - Suzaan Kritzinger-Klopper
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Matieland, 7602, South Africa
| | - Johannes J Le Roux
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Matieland, 7602, South Africa; School of Natural Sciences, Macquarie University, Sydney, 2109, Australia
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Wannicke N, Stüeken EE, Bauersachs T, Gehringer MM. Exploring the influence of atmospheric CO 2 and O 2 levels on the utility of nitrogen isotopes as proxy for biological N 2 fixation. Appl Environ Microbiol 2024; 90:e0057424. [PMID: 39320082 PMCID: PMC11497790 DOI: 10.1128/aem.00574-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 08/26/2024] [Indexed: 09/26/2024] Open
Abstract
Biological N2 fixation (BNF) is traced to the Archean. The nitrogen isotopic fractionation composition (δ15N) of sedimentary rocks is commonly used to reconstruct the presence of ancient diazotrophic ecosystems. While δ15N has been validated mostly using organisms grown under present-day conditions; it has not under the pre-Cambrian conditions, when atmospheric pO2 was lower and pCO2 was higher. Here, we explore δ15N signatures under three atmospheres with (i) elevated CO2 and no O2 (Archean), (ii) present-day CO2, and O2 and (iii) future elevated CO2, in marine and freshwater, heterocytous cyanobacteria. Additionally, we augment our data set from literature for more generalized dependencies of δ15N and the associated fractionation factor epsilon (ε = δ15Nbiomass - δ15NN2) during BNF in Archaea and Bacteria, including cyanobacteria, and habitats. The ε ranges between 3.70‰ and -4.96‰ with a mean ε value of -1.38 ± 0.95‰, for all bacteria, including cyanobacteria, across all tested conditions. The expanded data set revealed correlations of isotopic fractionation of BNF with CO2 concentrations, toxin production, and light, although within 1‰. Moreover, correlation showed significant dependency of ε to species type, C/N ratios and toxin production in cyanobacteria, albeit it within a small range (-1.44 ± 0.89‰). We therefore conclude that δ15N is likely robust when applied to the pre-Cambrian-like atmosphere, stressing the strong cyanobacterial bias. Interestingly, the increased fractionation (lower ε) observed in the toxin-producing Nodularia and Nostoc spp. suggests a heretofore unknown role of toxins in modulating nitrogen isotopic signals that warrants further investigation.IMPORTANCENitrogen is an essential element of life on Earth; however, despite its abundance, it is not biologically accessible. Biological nitrogen fixation is an essential process whereby microbes fix N2 into biologically usable NH3. During this process, the enzyme nitrogenase preferentially uses light 14N, resulting in 15N depleted biomass. This signature can be traced back in time in sediments on Earth, and possibly other planets. In this paper, we explore the influence of pO2 and pCO2 on this fractionation signal. We find the signal is stable, especially for the primary producers, cyanobacteria, with correlations to CO2, light, and toxin-producing status, within a small range. Unexpectedly, we identified higher fractionation signals in toxin-producing Nodularia and Nostoc species that offer insight into why some organisms produce these N-rich toxic secondary metabolites.
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Affiliation(s)
- Nicola Wannicke
- Leibniz Institute for Plasma Science and Technology e.V., Greifswald, Germany
| | - Eva E. Stüeken
- School of Earth & Environmental Sciences, University of St. Andrews, St. Andrews, United Kingdom
| | - Thorsten Bauersachs
- Institute of Organic Biochemistry in Geo-Systems, RWTH Aachen University, Aachen, Germany
| | - Michelle M. Gehringer
- Department of Microbiology, University of Kaiserslautern-Landau (RPTU), Kaiserslautern, Germany
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Doby JR, Siniscalchi CM, Pajuelo M, Krigbaum J, Soltis DE, Guralnick RP, Folk RA. Elemental and isotopic analysis of leaves predicts nitrogen-fixing phenotypes. Sci Rep 2024; 14:20065. [PMID: 39209870 PMCID: PMC11362558 DOI: 10.1038/s41598-024-70412-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Accepted: 08/16/2024] [Indexed: 09/04/2024] Open
Abstract
Nitrogen (N)-fixing symbiosis is critical to terrestrial ecosystems, yet possession of this trait is known for few plant species. Broader presence of the symbiosis is often indirectly determined by phylogenetic relatedness to taxa investigated via manipulative experiments. This data gap may ultimately underestimate phylogenetic, spatial, and temporal variation in N-fixing symbiosis. Still needed are simpler field or collections-based approaches for inferring symbiotic status. N-fixing plants differ from non-N-fixing plants in elemental and isotopic composition, but previous investigations have not tested predictive accuracy using such proxies. Here we develop a regional field study and demonstrate a simple classification model for fixer status using nitrogen and carbon content measurements, and stable isotope ratios (δ15N and δ13C), from field-collected leaves. We used mixed models and classification approaches to demonstrate that N-fixing phenotypes can be used to predict symbiotic status; the best model required all predictors and was 80-94% accurate. Predictions were robust to environmental context variation, but we identified significant variation due to native vs. non-native (exotic) status and phylogenetic affinity. Surprisingly, N content-not δ15N-was the strongest predictor, suggesting that future efforts combine elemental and isotopic information. These results are valuable for understudied taxa and ecosystems, potentially allowing higher-throughput field-based N-fixer assessments.
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Affiliation(s)
- Joshua R Doby
- Florida Museum of Natural History, University of Florida, Gainesville, FL, 32611, USA.
- Department of Biology, University of Florida, Gainesville, FL, 32611, USA.
| | | | - Mariela Pajuelo
- Florida Museum of Natural History, University of Florida, Gainesville, FL, 32611, USA
- Thompson Earth Systems Institute, University of Florida, Gainesville, FL, 32611, USA
| | - John Krigbaum
- Department of Anthropology, University of Florida, Gainesville, FL, 32611, USA
| | - Douglas E Soltis
- Florida Museum of Natural History, University of Florida, Gainesville, FL, 32611, USA
- Department of Biology, University of Florida, Gainesville, FL, 32611, USA
- Biodiversity Institute, University of Florida, Gainesville, FL, 32611, USA
| | - Robert P Guralnick
- Florida Museum of Natural History, University of Florida, Gainesville, FL, 32611, USA.
- Department of Biology, University of Florida, Gainesville, FL, 32611, USA.
- Biodiversity Institute, University of Florida, Gainesville, FL, 32611, USA.
| | - Ryan A Folk
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS, 39762, USA.
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5
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Zhou W, Lan Y, Matthew C, Nan Z. A Biological Comparison of Three Colletotrichum Species Associated with Alfalfa Anthracnose in Northern China. PLANTS (BASEL, SWITZERLAND) 2024; 13:1780. [PMID: 38999620 PMCID: PMC11244077 DOI: 10.3390/plants13131780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Revised: 06/19/2024] [Accepted: 06/24/2024] [Indexed: 07/14/2024]
Abstract
Anthracnose caused by various species of Colletotrichum is one of the most prevalent diseases in alfalfa worldwide that not only reduces forage yields but also severely compromises forage quality. A comprehensive survey was conducted in 2020 in the main production regions of northern China. The survey results showed that alfalfa anthracnose is prevalent in northern China, with the disease incidence ranging from 9% to 45% and the disease index from 5 to 17 (maximum possible score: 100). In total, 24 isolates were collected and identified as three Colletotrichum species (C. trifolii, C. truncatum and C. americae-borealis) based on morphological characteristics and phylogenetic analysis (combined sequences ITS, HIS3, ACT and GAPDH). The three species displayed remarkable environmental adaptability, exhibiting a capacity for growth, sporulation and conidial germination in temperatures ranging from 4 to 35 °C and in different nutrient conditions. Pathogenicity assays showed that C. trifolii was more virulent than the other two species, although the growth vigor (in terms of colony diameter, sporulation and conidial germination) of C. truncatum was the greatest.
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Affiliation(s)
- Wennan Zhou
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, Lanzhou University, Lanzhou 730020, China; (W.Z.); (Y.L.); (C.M.)
- Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Lanzhou University, Lanzhou 730020, China
- Engineering Research Center of Grassland Industry, Ministry of Education, Gansu Tech Innovation Centre of Western China Grassland Industry, Lanzhou University, Lanzhou 730020, China
- College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China
| | - Yanru Lan
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, Lanzhou University, Lanzhou 730020, China; (W.Z.); (Y.L.); (C.M.)
- Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Lanzhou University, Lanzhou 730020, China
- Engineering Research Center of Grassland Industry, Ministry of Education, Gansu Tech Innovation Centre of Western China Grassland Industry, Lanzhou University, Lanzhou 730020, China
- College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China
| | - Cory Matthew
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, Lanzhou University, Lanzhou 730020, China; (W.Z.); (Y.L.); (C.M.)
- Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Lanzhou University, Lanzhou 730020, China
- Engineering Research Center of Grassland Industry, Ministry of Education, Gansu Tech Innovation Centre of Western China Grassland Industry, Lanzhou University, Lanzhou 730020, China
- College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China
| | - Zhibiao Nan
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, Lanzhou University, Lanzhou 730020, China; (W.Z.); (Y.L.); (C.M.)
- Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Lanzhou University, Lanzhou 730020, China
- Engineering Research Center of Grassland Industry, Ministry of Education, Gansu Tech Innovation Centre of Western China Grassland Industry, Lanzhou University, Lanzhou 730020, China
- College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China
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6
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Deb S, Lewicka-Szczebak D, Rohe L. Microbial nitrogen transformations tracked by natural abundance isotope studies and microbiological methods: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 926:172073. [PMID: 38554959 DOI: 10.1016/j.scitotenv.2024.172073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 03/07/2024] [Accepted: 03/27/2024] [Indexed: 04/02/2024]
Abstract
Nitrogen is an essential nutrient in the environment that exists in multiple oxidation states in nature. Numerous microbial processes are involved in its transformation. Knowledge about very complex N cycling has been growing rapidly in recent years, with new information about associated isotope effects and about the microbes involved in particular processes. Furthermore, molecular methods that are able to detect and quantify particular processes are being developed, applied and combined with other analytical approaches, which opens up new opportunities to enhance understanding of nitrogen transformation pathways. This review presents a summary of the microbial nitrogen transformation, including the respective isotope effects of nitrogen and oxygen on different nitrogen-bearing compounds (including nitrates, nitrites, ammonia and nitrous oxide), and the microbiological characteristics of these processes. It is supplemented by an overview of molecular methods applied for detecting and quantifying the activity of particular enzymes involved in N transformation pathways. This summary should help in the planning and interpretation of complex research studies applying isotope analyses of different N compounds and combining microbiological and isotopic methods in tracking complex N cycling, and in the integration of these results in modelling approaches.
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Affiliation(s)
- Sushmita Deb
- Institute of Geological Sciences, University of Wrocław, pl. M. Borna 9, 50-204 Wrocław, Poland
| | | | - Lena Rohe
- Thünen Institute of Climate-Smart Agriculture, Bundesallee 65, 38116 Braunschweig, Germany
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Drouillard KG, Campbell L, Otieno D, Achiya J, Getabu A, Mwamburi J, Sitoki L, Omondi R, Shitandi A, Owuor B, Njiru J, Bullerjahn G, Mckay RM, Otiso KM, Tebbs E. Increasing mercury bioaccumulation and biomagnification rates of Nile perch (Lates niloticus L.) in Winam Gulf, Lake Victoria, Kenya. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 916:170059. [PMID: 38242476 PMCID: PMC11603132 DOI: 10.1016/j.scitotenv.2024.170059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 01/05/2024] [Accepted: 01/08/2024] [Indexed: 01/21/2024]
Abstract
The Nile perch (Lates niloticus L.) commercial fishery for Lake Victoria in East Africa is an important source of revenue and employment. We focused on shifts in food web structure and total mercury (THg) bioaccumulation and biomagnification in Nile perch, and lower food web items collected from Winam Gulf (Kenya) sampled 24 years apart (1998 and 2022). Stable isotope carbon (δ13C) values were higher in all species from 2022 compared to 1998. Stable nitrogen isotope (δ15N) values in baseline organisms were lower in 2022 compared to 1998. In Nile perch, δ15N values were correlated with total length, but the δ15N-length regressions were steeper in 1998 compared to 2022 except for one large (158 cm) Nile perch from 1998 with an uncharacteristically low δ15N value. Total Hg concentrations were lower in lower trophic species from 2022 compared to 1998. However, the THg bioaccumulation rate (as a function of fish length) in Nile perch was greater in 2022 compared to 1998 resulting in 24.2 % to 42.4 % higher wet weight dorsal THg concentrations in 2022 Nile perch for market slot size (50 to 85 cm) fish. The contrasting observations of increased THg bioaccumulation with size in 2022 against decreases in the rate of trophic increase with size and lower THg concentrations of lower food web items imply reduced fish growth and potential bioenergetic stressors on Winam Gulf Nile perch. All samples except 1 large Nile perch (139 cm total length collected in 2022) had THg concentrations below the European Union trade limit (500 ng/g wet weight). However, for more vulnerable individuals (women, children and frequent fish eaters), we recommend a decrease in maximum monthly meal consumption for 55-75 cm Nile perch from 16 meals per month calculated for 1998 to a limit of 8 meals per month calculated for 2022.
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Affiliation(s)
- Ken G Drouillard
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario, Canada.
| | - Linda Campbell
- School of the Environment, Saint Mary's University, Halifax, Nova Scotia, Canada
| | - Dennis Otieno
- Kenya Marine and Fisheries Research Institute, Kisumu, Kenya
| | - James Achiya
- Kenya Marine and Fisheries Research Institute, Kisumu, Kenya
| | | | - Job Mwamburi
- Kenya Marine and Fisheries Research Institute, Kisumu, Kenya
| | | | | | | | | | - James Njiru
- Kenya Marine and Fisheries Research Institute, Kisumu, Kenya
| | - George Bullerjahn
- Biological Sciences, Bowling Green State University, Bowling Green, OH, USA
| | - R Michael Mckay
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario, Canada
| | - Kefa M Otiso
- School of Earth, Environment and Society, Bowling Green State University, Bowling Green, OH, USA
| | - Emma Tebbs
- Department of Geography, King's College London, United Kingdom
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Ren W, Tian L, Querejeta JI. Tight coupling between leaf δ 13 C and N content along leaf ageing in the N 2 -fixing legume tree black locust (Robinia pseudoacacia L.). PHYSIOLOGIA PLANTARUM 2024; 176:e14235. [PMID: 38472162 DOI: 10.1111/ppl.14235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 01/29/2024] [Accepted: 02/08/2024] [Indexed: 03/14/2024]
Abstract
N2 -fixing legumes can strongly affect ecosystem functions by supplying nitrogen (N) and improving the carbon-fixing capacity of vegetation. Still, the question of how their leaf-level N status and carbon metabolism are coordinated along leaf ageing remains unexplored. Leaf tissue carbon isotopic composition (δ13 C) provides a useful indicator of time-integrated intrinsic water use efficiency (WUEi). Here, we quantified the seasonal changes of leaf δ13 C, N content on a mass and area basis (Nmass , Narea , respectively), Δ18 O (leaf 18 O enrichment above source water, a proxy of time-integrated stomatal conductance) and morphological traits in an emblematic N2 -fixing legume tree, the black locust (Robinia pseudoacacia L.), at a subtropical site in Southwest China. We also measured xylem, soil and rainwater isotopes (δ18 O, δ2 H) to characterize tree water uptake patterns. Xylem water isotopic data reveal that black locust primarily used shallow soil water in this humid habitat. Black locust exhibited a decreasing δ13 C along leaf ageing, which was largely driven by decreasing leaf Nmass , despite roughly constant Narea . In contrast, the decreasing δ13 C along leaf ageing was largely uncoupled from parallel increases in Δ18 O and leaf thickness. Leaf N content is used as a proxy of leaf photosynthetic capacity; thus, it plays a key role in determining the seasonality in δ13 C, whereas the roles of stomatal conductance and leaf morphology are minor. Black locust leaves can effectively adjust to changing environmental conditions along leaf ageing through LMA increases and moderate stomatal conductance reduction while maintaining constant Narea to optimize photosynthesis and carbon assimilation, despite declining leaf Nmass and δ13 C.
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Affiliation(s)
- Wei Ren
- Institute of International Rivers and Eco-Security, Yunnan University, Kunming, China
- Chongqing Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing, China
| | - Lide Tian
- Institute of International Rivers and Eco-Security, Yunnan University, Kunming, China
- Yunnan Key Laboratory of International Rivers and Transboundary Eco-security, Kunming, China
| | - José Ignacio Querejeta
- Centro de Edafología y Biología Aplicada del Segura, Consejo Superior de Investigaciones Científicas (CEBAS, CSIC), Murcia, Spain
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Soldatova E, Krasilnikov S, Kuzyakov Y. Soil organic matter turnover: Global implications from δ 13C and δ 15N signatures. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169423. [PMID: 38128662 DOI: 10.1016/j.scitotenv.2023.169423] [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: 09/06/2023] [Revised: 12/13/2023] [Accepted: 12/14/2023] [Indexed: 12/23/2023]
Abstract
The turnover and residence time of carbon (C) and nitrogen (N) in soil is a fundamental parameter reflecting the rates of soil organic matter (SOM) transformation and the contribution of soils to greenhouse gases fluxes. Based on the global database of the stable isotope composition of C (δ13C) and N (δ15N) depending on soil depth (171 profiles), we assessed С and N turnover and related them to climate, biome types and soil properties. The 13C and 15N discrimination between the litter horizon and mineral soil was evaluated to explain the key processes of litter transformation. The 13C and 15N discrimination by microbial utilization of litter and SOM, as well as the continuous increase of δ13C and δ15N with depth, enabled to assess C and N turnover within SOM. N turnover was two times faster than that of C, which reflects i) repeated N recycling by microorganisms accelerating N turnover, ii) C loss as CO2 and input of new C atoms to cycling, which reduces the C turnover within soil, and iii) generally slower turnover of N free persistent organic compounds (e.g. lignin, suberin, cellulose) compared to the N containing compounds (e.g. amino acids, ribonucleic acids). An increase in temperature and precipitation accelerated C and N turnover because: i) higher microbial activity and SOM decomposition rate, ii) larger soil moisture and fast diffusion of dissolved organics towards exoenzymes, iii) downward transport of 13C-enriched organic matter (e.g. sugars, amino acids), and iii) leaching of 15N-depleted nitrates from the topsoil into subsoil and losses from the whole soil profile. Temperature accelerates SOM turnover stronger than precipitation. The temperature increase by 10 °C accelerates the C and N turnover for 40 %. SOM turnover is boosted by decreasing C/N ratio because: i) SOM with a high C/N ratio originated from litter is converted to microbially-derived SOM in mineral soil characterized by a low C/N ratio; ii) litter with a low C/N ratio is decomposed faster than litter with a high C/N; iii) microbial carbon-use efficiency increases with N availability. The biome type affects SOM decomposition by i) climate: slower turnover under wet and cold conditions, and ii) by litter quality: faster utilization of leaves than needles. Thus, the fastest C turnover is common under evergreen forests and the lowest under mixed and coniferous ones, whereas temperature and C/N ratio are the main factors controlling SOM turnover. Concluding, the assessment of SOM turnover by δ13C and δ15N approach showed two times faster N turnover compared to C, and specifics of SOM turnover depending on the biomes as well as climate conditions.
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Affiliation(s)
- Evgeniya Soldatova
- Center for Isotope Biogeochemistry, Institute of Environmental and Agricultural Biology (X-BIO), University of Tyumen, 6 Volodarskogo Street, 625003 Tyumen, Russia; Laboratory of Mass Transport, Geological Institute of the Russian Academy of Sciences, 7с1 Pyzhevskiy Pereulok, 119017 Moscow, Russia.
| | - Sergey Krasilnikov
- Department of Land Surveying & Geo-Informatics, Research Centre for Deep Space Explorations, The Hong Kong Polytechnic University, ZN601, 6/F, Phase 8, 181 Chatham Road South, Kowloon, Hong Kong.
| | - Yakov Kuzyakov
- Department of Soil Science of Temperate Ecosystems, Department of Agricultural Soil Science, University of Goettingen, 2 Büsgenweg, 37077 Göttingen, Germany; Peoples Friendship University of Russia (RUDN University), 6 Miklukho-Maklaya Street, 117198 Moscow, Russia; Institute of Environmental Sciences, Kazan Federal University, 420049 Kazan, Russia.
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Song L, Wang A, Li Z, Kang R, Walters WW, Pan Y, Quan Z, Huang S, Fang Y. Large Seasonal Variation in Nitrogen Isotopic Abundances of Ammonia Volatilized from a Cropland Ecosystem and Implications for Regional NH 3 Source Partitioning. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:1177-1186. [PMID: 38170897 DOI: 10.1021/acs.est.3c08800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Ammonia (NH3) volatilization from agricultural lands is a main source of atmospheric reduced nitrogen species (NHx). Accurately quantifying its contribution to regional atmospheric NHx deposition is critical for controlling regional air nitrogen pollution. The stable nitrogen isotope composition (expressed by δ15N) is a promising indicator to trace atmospheric NHx sources, presupposing a reliable nitrogen isotopic signature of NH3 emission sources. To obtain more specific seasonal δ15N values of soil NH3 volatilization for reliable regional seasonal NH3 source partitioning, we utilized an active dynamic sampling technique to measure the δ15N-NH3 values volatilized from maize cropping land in northeast China. These values varied from -38.0 to -0.2‰, with a significantly lower rate-weighted value observed in the early period (May-June, -30.5 ± 6.7‰) as compared with the late period (July-October, -8.5 ± 4.3‰). Seasonal δ15N-NH3 variations were related to the main NH3 production pathway, degree of soil ammonium consumption, and soil environment. Bayesian isotope mixing model analysis revealed that without considering the seasonal δ15N variation in soil-volatilized NH3 could result in an overestimate by up to absolute 38% for agricultural volatile NH3 to regional atmospheric bulk ammonium deposition during July-October, further demonstrating that it is essential to distinguish seasonal δ15N profile of agricultural volatile NH3 in regional source apportionment.
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Affiliation(s)
- Linlin Song
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China
- Key Laboratory of Stable Isotope Techniques and Applications, Shenyang, Liaoning 110016, China
| | - Ang Wang
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China
- Key Laboratory of Stable Isotope Techniques and Applications, Shenyang, Liaoning 110016, China
| | - Zhengjie Li
- College of Biological Science and Technology, Central South University of Forestry and Technology, Changsha, Hunan 410004, China
| | - Ronghua Kang
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China
- Key Laboratory of Stable Isotope Techniques and Applications, Shenyang, Liaoning 110016, China
| | - Wendell W Walters
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Yuepeng Pan
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
| | - Zhi Quan
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China
- Key Laboratory of Stable Isotope Techniques and Applications, Shenyang, Liaoning 110016, China
| | - Shaonan Huang
- Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions, Ministry of Education, College of Environment and Planning, Henan University, Kaifeng 475004, China
| | - Yunting Fang
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China
- Key Laboratory of Stable Isotope Techniques and Applications, Shenyang, Liaoning 110016, China
- Qingyuan Forest CERN, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China
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11
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Glidden A, Seager S, Petkowski JJ, Ono S. Can Isotopologues Be Used as Biosignature Gases in Exoplanet Atmospheres? Life (Basel) 2023; 13:2325. [PMID: 38137926 PMCID: PMC10744769 DOI: 10.3390/life13122325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 10/25/2023] [Accepted: 11/15/2023] [Indexed: 12/24/2023] Open
Abstract
Isotopologue ratios are anticipated to be one of the most promising signs of life that can be observed remotely. On Earth, carbon isotopes have been used for decades as evidence of modern and early metabolic processes. In fact, carbon isotopes may be the oldest evidence for life on Earth, though there are alternative geological processes that can lead to the same magnitude of fractionation. However, using isotopologues as biosignature gases in exoplanet atmospheres presents several challenges. Most significantly, we will only have limited knowledge of the underlying abiotic carbon reservoir of an exoplanet. Atmospheric carbon isotope ratios will thus have to be compared against the local interstellar medium or, better yet, their host star. A further substantial complication is the limited precision of remote atmospheric measurements using spectroscopy. The various metabolic processes that cause isotope fractionation cause less fractionation than anticipated measurement precision (biological fractionation is typically 2 to 7%). While this level of precision is easily reachable in the laboratory or with special in situ instruments, it is out of reach of current telescope technology to measure isotope ratios for terrestrial exoplanet atmospheres. Thus, gas isotopologues are poor biosignatures for exoplanets given our current and foreseeable technological limitations.
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Affiliation(s)
- Ana Glidden
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Sara Seager
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Janusz J. Petkowski
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- JJ Scientific, Mazowieckie, 02-792 Warsaw, Poland
- Faculty of Environmental Engineering, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland
| | - Shuhei Ono
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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12
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García-López JV, Redondo-Gómez S, Flores-Duarte NJ, Zunzunegui M, Rodríguez-Llorente ID, Pajuelo E, Mateos-Naranjo E. Exploring through the use of physiological and isotopic techniques the potential of a PGPR-based biofertilizer to improve nitrogen fertilization practices efficiency in strawberry cultivation. FRONTIERS IN PLANT SCIENCE 2023; 14:1243509. [PMID: 37780506 PMCID: PMC10540466 DOI: 10.3389/fpls.2023.1243509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 08/28/2023] [Indexed: 10/03/2023]
Abstract
The use of microorganisms as a biofertilizer in strawberry has focused mainly on pathogen biocontrol, which has led to the underestimation of the potential of microorganisms for the improvement of nutritional efficiency in this crop. A study was established to investigate the impact of a plant growth-promoting rhizobacteria (PGPR) based biofertilizer integrated by self-compatible stress tolerant strains with multiple PGP properties, including atmospheric nitrogen fixation, on strawberry (Fragaria × ananassa cv. Rociera) tolerance to N deficiency in terms of growth and physiological performance. After 40 days of nitrogen fertilization shortage, inoculated plants were able to maintain root development and fertility structures (i.e. fruits and flowers) at a level similar to plants properly fertilized. In addition, inoculation lessened the negative impact of nitrogen deficiency on leaves' dry weight and relative water content. This effect was mediated by a higher root/shoot ratio, which would have allowed them to explore larger volumes of soil for the acquisition of water. Moreover, inoculation was able to buffer up to 50% of the reduction in carbon assimilation capacity, due to its positive effect on the diffusion efficiency of CO2 and the biochemical capacity of photosynthesis, as well as on the activity of photosystem II light harvesting. Furthermore, the higher leaf C/N ratio and the maintained δ15N values close to control plants were related to positive bacterial effects at the level of the plant nutritional balance. Despite these positive effects, the application of the bacterial inoculum was unable to completely counteract the restriction of fertilization, being necessary to apply a certain amount of synthetic fertilizer for the strawberry nutrition. However, according to our results, the complementary effect of this PGPR-based biofertilizer could provide a higher efficiency in environmental and economic yields on this crop.
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Affiliation(s)
- Jesús V. García-López
- Servicio General de Invernadero, Centro de Investigación, Tecnología e Innovación de la Universidad de Sevilla (CITIUS), Seville, Spain
| | - Susana Redondo-Gómez
- Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | - Noris J. Flores-Duarte
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, Seville, Spain
| | - María Zunzunegui
- Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | | | - Eloísa Pajuelo
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, Seville, Spain
| | - Enrique Mateos-Naranjo
- Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Seville, Spain
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13
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El-Sherbeny TMS, Mousa AM, Zhran MA. Response of peanut (Arachis hypogaea L.) plant to bio-fertilizer and plant residues in sandy soil. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2023; 45:253-265. [PMID: 35697953 PMCID: PMC9884651 DOI: 10.1007/s10653-022-01302-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 05/13/2022] [Indexed: 06/15/2023]
Abstract
Nitrogen (N) fertilizer has been intensively used to improve peanut productivity. However, the high cost of N fertilizer, and the need for sustainable alternative fertilizer sources have increased the strategic importance of nitrogen fixation (NF). Thus, field experiments were conducted in an experimental farm with a drip irrigation system, at the Atomic Energy Authority, Inshas, Egypt, in order to measure the impact of efficiency symbiotic Bradyrhizobium sp. and asymbiotic Azotobacter sp. on NF, from air and soil, in the presence or absence of plant residues on the growth and yield of peanut plant. All treatments received nitrogen fertilizer at a rate of 72 kg N per hectare. Nitrogen dose was applied using ammonium sulphate 15N labeled of 10% atom excess from the peanut. Results indicated that the application of Bradyrhizobium sp. with plant residues significantly increased fresh and dry weight/m2, pod and seed weight/plant-1,100- seed weight, and biological yield kg ha-1, where the highest mean values of seed yield (4648 and 4529 kg ha-1), oil % (52.29 and 52.21%), seed protein percentage (16.09 and 15.89%), as well as nitrogen derived from air (63.14 and 66.20%) in the first and second seasons were recorded under the application of Bradyrhizobium sp, respectively. Bradyrhizobium sp. inoculation showed nearly close portions of Ndfa to those recorded with Azotobacter sp., in both the presence and absence of plant residue application through the two seasons. The investigated yield signs and their properties were significantly enhanced by bacterial inoculation with plant residue application. The present study shows that both possibility of NF of peanut, and nitrogen uptake in the soil are enhanced by field inoculation with effective Bradyrhizobium sp. with plant residue application. In practice, inoculation is a great strategy to improve soil fertility for subsequent planting, since it helps boost the import of nitrogen from plant biomass into the soil.
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Affiliation(s)
- T M S El-Sherbeny
- Nuclear Research Center, Plant Research Department, Egyptian Atomic Energy Authority, Cairo, Egypt
| | - Abeer M Mousa
- Nuclear Research Center, Soil and Water Research Department, Egyptian Atomic Energy Authority, Cairo, 13759, Egypt
| | - Mostafa A Zhran
- Nuclear Research Center, Soil and Water Research Department, Egyptian Atomic Energy Authority, Cairo, 13759, Egypt.
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14
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Mathesius U. Are legumes different? Origins and consequences of evolving nitrogen fixing symbioses. JOURNAL OF PLANT PHYSIOLOGY 2022; 276:153765. [PMID: 35952452 DOI: 10.1016/j.jplph.2022.153765] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 07/01/2022] [Accepted: 07/03/2022] [Indexed: 05/14/2023]
Abstract
Nitrogen fixing symbioses between plants and bacteria are ancient and, while not numerous, are formed in diverse lineages of plants ranging from microalgae to angiosperms. One symbiosis stands out as the most widespread one is that between legumes and rhizobia, leading to the formation of nitrogen-fixing nodules. The legume family is one of the largest and most diverse group of plants and legumes have been used by humans since the beginning of agriculture, both as high nitrogen food, as well as pastures and rotation crops. One open question is whether their ability to form a nitrogen-fixing symbiosis has contributed to legumes' success, and whether legumes have any unique characteristics that have made them more diverse and widespread than other groups of plants. This review examines the evolutionary journey that has led to the diversification of legumes, in particular its nitrogen-fixing symbiosis, and asks four questions to investigate which legume traits might have contributed to their success: 1. In what ways do legumes differ from other plant groups that have evolved nitrogen-fixing symbioses? In order to answer this question, the characteristics of the symbioses, and efficiencies of nitrogen fixation are compared between different groups of nitrogen fixing plants. 2. Could certain unique features of legumes be a reason for their success? This section examines the manifestations and possible benefits of a nitrogen-rich 'lifestyle' in legumes. 3. If nitrogen fixation was a reason for such a success, why have some species lost the symbiosis? Formation of symbioses has trade-offs, and while these are less well known for non-legumes, there are known energetic and ecological reasons for loss of symbiotic potential in legumes. 4. What can we learn from the unique traits of legumes for future crop improvements? While exploiting some of the physiological properties of legumes could be used to improve legume breeding, our increasing molecular understanding of the essential regulators of root nodule symbioses raise hope of creating new nitrogen fixing symbioses in other crop species.
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Affiliation(s)
- Ulrike Mathesius
- Division of Plant Sciences, Research School of Biology, The Australian National University, 134 Linnaeus Way, Canberra, ACT, 2601, Australia.
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15
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Harris E, Yu L, Wang YP, Mohn J, Henne S, Bai E, Barthel M, Bauters M, Boeckx P, Dorich C, Farrell M, Krummel PB, Loh ZM, Reichstein M, Six J, Steinbacher M, Wells NS, Bahn M, Rayner P. Warming and redistribution of nitrogen inputs drive an increase in terrestrial nitrous oxide emission factor. Nat Commun 2022; 13:4310. [PMID: 35879348 PMCID: PMC9314393 DOI: 10.1038/s41467-022-32001-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 07/11/2022] [Indexed: 11/17/2022] Open
Abstract
Anthropogenic nitrogen inputs cause major negative environmental impacts, including emissions of the important greenhouse gas N2O. Despite their importance, shifts in terrestrial N loss pathways driven by global change are highly uncertain. Here we present a coupled soil-atmosphere isotope model (IsoTONE) to quantify terrestrial N losses and N2O emission factors from 1850-2020. We find that N inputs from atmospheric deposition caused 51% of anthropogenic N2O emissions from soils in 2020. The mean effective global emission factor for N2O was 4.3 ± 0.3% in 2020 (weighted by N inputs), much higher than the surface area-weighted mean (1.1 ± 0.1%). Climate change and spatial redistribution of fertilisation N inputs have driven an increase in global emission factor over the past century, which accounts for 18% of the anthropogenic soil flux in 2020. Predicted increases in fertilisation in emerging economies will accelerate N2O-driven climate warming in coming decades, unless targeted mitigation measures are introduced.
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Affiliation(s)
- E Harris
- Swiss Data Science Centre, ETH Zurich, 8092, Zurich, Switzerland.
- Functional Ecology Research Group, Institute of Ecology, University of Innsbruck, 6020, Innsbruck, Austria.
| | - L Yu
- Institute of Environment and Ecology, Tsinghua Shenzhen International Graduate School (SIGS), Tsinghua University, Shenzhen, 518055, China
- Laboratory for Air Pollution & Environmental Technology, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600, Duebendorf, Switzerland
| | - Y-P Wang
- Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, VIC, 3195, Australia
| | - J Mohn
- Laboratory for Air Pollution & Environmental Technology, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600, Duebendorf, Switzerland
| | - S Henne
- Laboratory for Air Pollution & Environmental Technology, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600, Duebendorf, Switzerland
| | - E Bai
- Key Laboratory of Geographical Processes and Ecological Security of Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun, 130024, China
| | - M Barthel
- Department of Environmental Systems Science, ETH Zurich, 8092, Zurich, Switzerland
| | - M Bauters
- Isotope Bioscience Laboratory - ISOFYS, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - P Boeckx
- Isotope Bioscience Laboratory - ISOFYS, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - C Dorich
- Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, 80523, CO, USA
| | - M Farrell
- CSIRO Agriculture and Food, Locked bag 2, Glen Osmond, SA, 5064, Australia
| | - P B Krummel
- Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, VIC, 3195, Australia
| | - Z M Loh
- Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, VIC, 3195, Australia
| | - M Reichstein
- Department of Biogeochemical Integration, Max Planck Institute for Biogeochemistry, Jena, Germany
| | - J Six
- Department of Environmental Systems Science, ETH Zurich, 8092, Zurich, Switzerland
| | - M Steinbacher
- Laboratory for Air Pollution & Environmental Technology, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600, Duebendorf, Switzerland
| | - N S Wells
- Centre for Coastal Biogeochemistry, Southern Cross University, Lismore, NSW, 2480, Australia
- Department of Soil and Physical Sciences, Agriculture and Life Sciences, Lincoln University, Lincoln, 7647, New Zealand
| | - M Bahn
- Functional Ecology Research Group, Institute of Ecology, University of Innsbruck, 6020, Innsbruck, Austria
| | - P Rayner
- School of Geography, Earth and Atmospheric Sciences, University of Melbourne, Parkville, VIC, 3052, Australia
- Melbourne Climate Futures Climate and Energy College, University of Melbourne, Parkville, VIC, 3052, Australia
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16
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Warrington S, Ellis AG, Keet JH, Le Roux JJ. How does familiarity in rhizobial interactions impact the performance of invasive and native legumes? NEOBIOTA 2022. [DOI: 10.3897/neobiota.72.79620] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Mutualisms can be disrupted when non-native plants are introduced into novel environments, potentially impacting their establishment success. Introduced species can reassemble mutualisms by forming novel associations with resident biota or by maintaining familiar associations when they are co-introduced with their mutualists. Invasive Australian Acacia species in South Africa have formed nitrogen-fixing rhizobium mutualisms using both pathways.
Here we examined the contributions of novel vs familiar rhizobial associations to the performance of Acacia saligna across different soils within South Africa’s Core Cape Subregion (CCR), and the concomitant impacts of exotic rhizobia on the endemic legume, Psoralea pinnata. We grew each legume with and without Australian Bradyrhizobium strains across various CCR soil types in a glasshouse. We identified root nodule rhizobium communities associating with seedlings grown in each treatment combination using next-generation sequencing (NGS) techniques.
Our results show that different CCR soils affected growth performances of seedlings for both species while the addition of Australian bradyrhizobia affected growth performances of A. saligna, but not P. pinnata. NGS data revealed that each legume associated mostly with their familiar rhizobial partners, regardless of soil conditions or inoculum treatment. Acacia saligna predominantly associated with Australian bradyrhizobia, even when grown in soils without inoculum, while P. pinnata largely associated with native South African Mesorhizobium strains.
Our study suggests that exotic Australian bradyrhizobia are already present and widespread in pristine CCR soils, and that mutualist limitation is not an impediment to further acacia invasion in the region. The ability of P. pinnata to sanction Australian Bradyrhizobium strains suggests that this species may be a good candidate for restoration efforts following the removal of acacias in CCR habitats.
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17
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Trapp T, Inácio CDT, Ciotta MN, Hindersmann J, Lima AP, Dos Santos TS, Ferreira GW, Morais GP, de Conti L, Comin JJ, Loss A, Giacomini SJ, Lourenzi CR, Rozane DE, Brunetto G. Natural abundance analysis of the role played by 15 N as indicator for the certification of organic-system deriving food. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2022; 102:330-340. [PMID: 34097746 DOI: 10.1002/jsfa.11362] [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: 10/23/2020] [Revised: 05/12/2021] [Accepted: 06/07/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND The natural abundance of stable isotope 15 N (δ15 N) in production systems has emerged as an alternative to distinguish organic products from conventional ones. This study evaluated the use of δ15 N values recorded for nitrogen fertilizers, soil and plant tissue in order to set the differences between organic and conventional agricultural production systems applied to rice, potatoes, apple and banana crops. RESULTS Values of δ15 N recorded for N sources ranged from +5.58‰ to +18.27‰ and from -3.55‰ to +3.19‰ in organic and synthetic fertilizers, respectively. Values recorded for δ15 N in food from organic rice, potatoes and banana farms were higher than values recorded for δ15 N in conventional farms; the same was observed for values recorded for δ15 N in leaves from the four crops. CONCLUSION Results have allowed for differentiation between production systems due to values of δ15 N recorded in leaves of all crops and food, for rice, potatoes and banana trees. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Talita Trapp
- Rural Engineering Department, Center of Agrarian Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Caio de Teves Inácio
- Embrapa Soils, National Research Center of Soils, Brazilian Agricultural Research Corporation (Embrapa), Rio de Janeiro, Brazil
| | - Marlise Nara Ciotta
- Experimental Station of Lages, Agricultural Research and Rural Extension Company of Santa Catarina (Epagri), Lages, Brazil
| | - Jacson Hindersmann
- Soil Science Department, Federal University of Santa Maria, Santa Maria, Brazil
| | - Andria Paula Lima
- Rural Engineering Department, Center of Agrarian Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Thiago Stacowski Dos Santos
- Rural Engineering Department, Center of Agrarian Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Guilherme Wilbert Ferreira
- Rural Engineering Department, Center of Agrarian Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Gildean Portela Morais
- Rural Engineering Department, Center of Agrarian Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Lessandro de Conti
- Santo Augusto Campus, Federal Institute of Education, Science and Technology Farroupilha, Santo Augusto, Brazil
| | - Jucinei José Comin
- Rural Engineering Department, Center of Agrarian Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Arcângelo Loss
- Rural Engineering Department, Center of Agrarian Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | | | - Cledimar Rogério Lourenzi
- Rural Engineering Department, Center of Agrarian Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | | | - Gustavo Brunetto
- Soil Science Department, Federal University of Santa Maria, Santa Maria, Brazil
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18
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Horacek M, Papesch W. Storage Changes Stable Isotope Composition of Cucumbers. FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 2021. [DOI: 10.3389/fsufs.2021.781158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Vegetable food stuff produced under controlled and identical conditions from one farm of identical “age” (batch) has a similar isotopic composition. This fact can be used to control the origin of vegetables. This question is of special relevance when food-contaminations have to be traced back to the producer, or certain production claims have to be controlled. However, as vegetables are harvested, brought to whole-sale merchants and to retail shops, where they remain until being bought by the consumer, one has to consider possible changes in isotopic composition during this transfer period, when comparing vegetables of questioned origin with reference samples taken directly from the field/producer. We investigated changes in the isotope composition of vegetables during storage by studying as an example cucumbers from one batch. We stored the cucumbers in a vegetable storage under controlled conditions and removed one sample every day and analyzed its isotopic composition. We found changes in the δ15N and δ18O isotope values over the investigated period of 21 days, with both parameters showing positive linear correlations, and maximum enrichments with time of more than 1.5‰ for δ15N and more than 2‰ for δ18O. However, within the interval the samples remained in a saleable condition the isotope variations remained more or less within the variability of the sample batch. Our study demonstrates that changes in the isotopic signature in vegetables might occur after harvest during storage and have to be taken into account when (commercial) samples collected in a market are investigated.
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19
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Arcas-Pilz V, Parada F, Villalba G, Rufí-Salis M, Rosell-Melé A, Gabarrell Durany X. Improving the Fertigation of Soilless Urban Vertical Agriculture Through the Combination of Struvite and Rhizobia Inoculation in Phaseolus vulgaris. FRONTIERS IN PLANT SCIENCE 2021; 12:649304. [PMID: 34113362 PMCID: PMC8186444 DOI: 10.3389/fpls.2021.649304] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 04/27/2021] [Indexed: 06/12/2023]
Abstract
Soilless crop production is a viable way to promote vertical agriculture in urban areas, but it relies extensively on the use of mineral fertilizer. Thus, the benefits of fresher, local food and avoiding the transportation and packaging associated with food import could be counteracted by an increase in nutrient-rich wastewater, which could contribute to freshwater and marine eutrophication. The present study aimed to explore the use of mineral fertilizer substitutes in soilless agriculture. Phaseolus vulgaris (common bean) was fertilized with a combination of slow-releasing fertilizer struvite (a source of N, P, and Mg), which is a byproduct of wastewater treatment plants, and inoculation with Rhizobium (a N2-fixing soil bacteria). The experiment included three bean-production lines: (A) 2 g/plant of struvite and rhizobial inoculation; (B) 5 g/plant of struvite and rhizobial inoculation, both irrigated with a Mg-, P-, and N-free nutrient solution; and (C) a control treatment that consisted of irrigation with a full nutrient solution and no inoculation. Plant growth, development, yields, and nutrient contents were determined at 35, 62, and 84 days after transplanting as well as biological N2 fixation, which was determined using the 15N natural abundance method. Treatments A and B resulted in lower total yields per plant than the control C treatment (e.g., 59.35 ± 26.4 g plant-1 for A, 74.2 ± 23.0 g plant-1 for B, and 147.71 ± 45.3 g plant-1 for C). For A and B, the nodulation and N2 fixation capacities appeared to increase with the amount of initially available struvite, but, over time, deficient levels of Mg were reached as well as nearly deficient levels of P, which could explain the lower yields. Nevertheless, we conclude that the combination of struvite and N2-fixing bacteria covered the N needs of plants throughout the growth cycle. However, further studies are needed to determine the optimal struvite quantities for vertical agriculture systems that can meet the P and Mg requirements throughout the lifetime of the plants.
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Affiliation(s)
- Verónica Arcas-Pilz
- Sostenipra Research Group (2017 SGR 1683), Institut de Ciència i Tecnologia Ambientals (CEX2019-000940-M), Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Felipe Parada
- Sostenipra Research Group (2017 SGR 1683), Institut de Ciència i Tecnologia Ambientals (CEX2019-000940-M), Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Gara Villalba
- Sostenipra Research Group (2017 SGR 1683), Institut de Ciència i Tecnologia Ambientals (CEX2019-000940-M), Universitat Autònoma de Barcelona, Barcelona, Spain
- Department of Chemical, Biological and Environmental Engineering, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Martí Rufí-Salis
- Sostenipra Research Group (2017 SGR 1683), Institut de Ciència i Tecnologia Ambientals (CEX2019-000940-M), Universitat Autònoma de Barcelona, Barcelona, Spain
- Department of Chemical, Biological and Environmental Engineering, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Antoni Rosell-Melé
- Institut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain
| | - Xavier Gabarrell Durany
- Sostenipra Research Group (2017 SGR 1683), Institut de Ciència i Tecnologia Ambientals (CEX2019-000940-M), Universitat Autònoma de Barcelona, Barcelona, Spain
- Department of Chemical, Biological and Environmental Engineering, Universitat Autònoma de Barcelona, Barcelona, Spain
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20
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Xu‐Ri, Dai D, Xu X. The symbiotic nitrogen fixation by legumes in a legume‐companion and a legume‐dominant alpine steppe on the central Tibetan Plateau. Ecol Res 2021. [DOI: 10.1111/1440-1703.12221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xu‐Ri
- Key Laboratory of Alpine Ecology Institute of Tibetan Plateau Research, Chinese Academy of Sciences Beijing China
- CAS Center for Excellence in Tibetan Plateau Earth Sciences Beijing China
| | - Dongxue Dai
- Key Laboratory of Alpine Ecology Institute of Tibetan Plateau Research, Chinese Academy of Sciences Beijing China
- University of Chinese Academy of Sciences Beijing China
| | - Xingliang Xu
- Key Laboratory of Ecosystem Network Observation and Modelling Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences Beijing China
- State Key Lab of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences Beijing China
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21
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Isotopic constraints on plant nitrogen acquisition strategies during ecosystem retrogression. Oecologia 2020; 192:603-614. [PMID: 32025895 DOI: 10.1007/s00442-020-04606-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 01/16/2020] [Indexed: 10/25/2022]
Abstract
Plant root associations with microbes such as mycorrhizal fungi or N-fixing bacteria enable ecosystems to tap pools of nitrogen (N) that might otherwise be inaccessible, including atmospheric N or N in large soil organic molecules. Such microbially assisted N-foraging strategies may be particularly important in late-successional retrogressive ecosystems where productivity is low and soil nutrients are scarce. Here, we use natural N-stable isotopic composition to constrain pathways of N supplies to different plant functional groups across a well-studied natural soil fertility gradient that includes a highly retrogressive stage. We demonstrate that ectomycorrhizal fungi, ericoid mycorrhizal fungi, and N-fixing bacteria support forest N supplies at all stages of ecosystem succession, from relatively young, N-rich/phosphorus (P)-rich sites, to ancient sites (ca. 500 ky) where both N supplies and P supplies are exceedingly low. Microbially mediated N sources are most important in older ecosystems with very low soil nutrient availability, accounting for 75-96% of foliar N at the oldest, least fertile sites. These isotopically ground findings point to the key role of plant-microbe associations in shaping ecosystem processes and functioning, particularly in retrogressive-phase forest ecosystems.
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22
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Wang Y, Schimel JP, Nisbet RM, Gardea-Torresdey JL, Holden PA. Soybeans Grown with Carbonaceous Nanomaterials Maintain Nitrogen Stoichiometry by Assimilating Soil Nitrogen to Offset Impaired Dinitrogen Fixation. ACS NANO 2020; 14:585-594. [PMID: 31825596 DOI: 10.1021/acsnano.9b06970] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Engineered nanomaterials (ENMs) can enter agroecosystems because of their widespread use and disposal. Within soil, ENMs may affect legumes and their dinitrogen (N2) fixation, which are critical for food supply and N-cycling. Prior research focusing on end point treatment effects has reported that N2-fixing symbioses in an important food legume, soybean, can be impaired by ENMs. Yet, it remains unknown how ENMs can influence the actual amounts of N2 fixed and what plant total N contents are since plants can also acquire N from the soil. We determined the effects of one already widespread and two rapidly expanding carbonaceous nanomaterials (CNMs: carbon black, multiwalled carbon nanotubes, and graphene; each at three concentrations) on the N economy of soil-grown soybeans. Unlike previous studies, this research focused on processes and interactions within a plant-soil-microbial system. We found that total plant N accumulation was unaffected by CNMs. However, as shown by 15N isotope analyses, CNMs significantly diminished soybean N2 fixation (by 31-78%). Plants maintained N stoichiometry by assimilating compensatory N from the soil, accompanied by increased net soil N mineralization. Our findings suggest that CNMs could undermine the role of legume N2 fixation in supplying N to agroecosystems. Maintaining productivity in leguminous agriculture experiencing such effects would require more fossil-fuel-intensive N fertilizer and increase associated economic and environmental costs. This work highlights the value of a process-based analysis of a plant-soil-microbial system for assessing how ENMs in soil can affect legume N2 fixation and N-cycling.
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Affiliation(s)
- Ying Wang
- Bren School of Environmental Science and Management , University of California , Santa Barbara , California 93106 , United States
- Earth Research Institute , University of California , Santa Barbara , California 93106 , United States
- University of California Center for Environmental Implications of Nanotechnology , University of California , Santa Barbara , California 93106 , United States
| | - Joshua P Schimel
- Earth Research Institute , University of California , Santa Barbara , California 93106 , United States
- University of California Center for Environmental Implications of Nanotechnology , University of California , Santa Barbara , California 93106 , United States
- Department of Ecology, Evolution and Marine Biology , University of California , Santa Barbara , California 93106 , United States
| | - Roger M Nisbet
- Earth Research Institute , University of California , Santa Barbara , California 93106 , United States
- University of California Center for Environmental Implications of Nanotechnology , University of California , Santa Barbara , California 93106 , United States
- Department of Ecology, Evolution and Marine Biology , University of California , Santa Barbara , California 93106 , United States
| | - Jorge L Gardea-Torresdey
- University of California Center for Environmental Implications of Nanotechnology , University of California , Santa Barbara , California 93106 , United States
- Department of Chemistry and Biochemistry , University of Texas at El Paso , El Paso , Texas 79968 , United States
| | - Patricia A Holden
- Bren School of Environmental Science and Management , University of California , Santa Barbara , California 93106 , United States
- Earth Research Institute , University of California , Santa Barbara , California 93106 , United States
- University of California Center for Environmental Implications of Nanotechnology , University of California , Santa Barbara , California 93106 , United States
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23
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McCue MD, Javal M, Clusella‐Trullas S, Le Roux JJ, Jackson MC, Ellis AG, Richardson DM, Valentine AJ, Terblanche JS. Using stable isotope analysis to answer fundamental questions in invasion ecology: Progress and prospects. Methods Ecol Evol 2019. [DOI: 10.1111/2041-210x.13327] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Marshall D. McCue
- Sable Systems International Las Vegas NV USA
- Department of Conservation Ecology and Entomology Centre for Invasion Biology Stellenbosch University Stellenbosch South Africa
| | - Marion Javal
- Department of Conservation Ecology and Entomology Centre for Invasion Biology Stellenbosch University Stellenbosch South Africa
| | - Susana Clusella‐Trullas
- Centre for Invasion Biology Department of Botany and Zoology Stellenbosch University Stellenbosch South Africa
| | - Johannes J. Le Roux
- Centre for Invasion Biology Department of Botany and Zoology Stellenbosch University Stellenbosch South Africa
- Department of Biological Sciences Macquarie University NSW Australia
| | - Michelle C. Jackson
- Centre for Invasion Biology Department of Botany and Zoology Stellenbosch University Stellenbosch South Africa
- Department of Life Sciences Imperial College London Ascot UK
- Department of Zoology Oxford University Oxford UK
| | - Allan G. Ellis
- Department of Botany and Zoology Stellenbosch University Stellenbosch South Africa
| | - David M. Richardson
- Centre for Invasion Biology Department of Botany and Zoology Stellenbosch University Stellenbosch South Africa
| | - Alex J. Valentine
- Department of Botany and Zoology Stellenbosch University Stellenbosch South Africa
| | - John S. Terblanche
- Department of Conservation Ecology and Entomology Centre for Invasion Biology Stellenbosch University Stellenbosch South Africa
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24
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Padda KP, Puri A, Chanway C. Endophytic nitrogen fixation – a possible ‘hidden’ source of nitrogen for lodgepole pine trees growing at unreclaimed gravel mining sites. FEMS Microbiol Ecol 2019; 95:5606785. [DOI: 10.1093/femsec/fiz172] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 10/23/2019] [Indexed: 01/19/2023] Open
Abstract
ABSTRACTLodgepole pine (Pinus contorta var. latifolia) trees have been thriving on unreclaimed gravel mining sites in British Columbia, Canada, with tissue nitrogen-content and growth-rate unaffected by extremely low soil nitrogen-levels. This indicates that pine trees could be accessing a hidden nitrogen source to fulfill their nitrogen requirements – possibly via endophytic nitrogen-fixation. Endophytic bacteria originally isolated from native pine trees growing at gravel sites were selected (n = 14) for in vitro nitrogen-fixation assays and a year long greenhouse study to test the overall hypothesis that naturally occurring endophytic nitrogen-fixing bacteria sustain pine tree growth under nitrogen-limited conditions. Each of the 14 bacteria colonized the internal tissues of pine trees in the greenhouse study and fixed significant amounts of nitrogen from atmosphere (23%–53%) after one year as estimated through 15N isotope dilution assay. Bacterial inoculation also significantly enhanced the length (31%–64%) and biomass (100%–311%) of pine seedlings as compared to the non-inoculated control treatment. In addition, presence of the nifH gene was confirmed in all 14 bacteria. Our results support the possibility that pine trees associate with nitrogen-fixing bacteria, capable of endophytic colonization, to survive at unreclaimed gravel mining pits and this association could potentially be utilized for effective reclamation of highly disturbed sites in a sustainable manner.
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Affiliation(s)
- Kiran Preet Padda
- Faculty of Land and Food Systems, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Akshit Puri
- Faculty of Land and Food Systems, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Chris Chanway
- Faculty of Land and Food Systems, The University of British Columbia, Vancouver, British Columbia, Canada
- Faculty of Forestry, The University of British Columbia, Vancouver, British Columbia, Canada
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25
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Morris TL, Barger NN, Cramer MD. Ecophysiological traits of invasive alien Acacia cyclops
compared to co-occuring native species in Strandveld vegetation of the Cape Floristic Region. AUSTRAL ECOL 2019. [DOI: 10.1111/aec.12827] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Taryn L. Morris
- Department of Ecology and Evolutionary Biology; University of Colorado; Boulder Colorado USA
- Department of Biological Sciences; University of Cape Town; Private Bag X3 Rondebosch 7701 South Africa
| | - Nichole N. Barger
- Department of Ecology and Evolutionary Biology; University of Colorado; Boulder Colorado USA
| | - Michael D. Cramer
- Department of Biological Sciences; University of Cape Town; Private Bag X3 Rondebosch 7701 South Africa
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26
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Kuramae EE, Leite MFA, Suleiman AKA, Gough CM, Castillo BT, Faller L, Franklin RB, Syring J. Wood Decay Characteristics and Interspecific Interactions Control Bacterial Community Succession in Populus grandidentata (Bigtooth Aspen). Front Microbiol 2019; 10:979. [PMID: 31143163 PMCID: PMC6520631 DOI: 10.3389/fmicb.2019.00979] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 04/18/2019] [Indexed: 02/01/2023] Open
Abstract
Few studies have investigated bacterial community succession and the role of bacterial decomposition over a continuum of wood decay. Here, we identified how (i) the diversity and abundance of bacteria changed along a chronosequence of decay in Populus grandidentata (bigtooth aspen); (ii) bacterial community succession was dependent on the physical and chemical characteristics of the wood; (iii) interspecific bacterial interactions may mediate community structure. Four hundred and fifty-nine taxa were identified through Illumina sequencing of 16S rRNA amplicons from samples taken along a continuum of decay, representing standing dead trees, downed wood, and soil. Community diversity increased as decomposition progressed, peaking in the most decomposed trees. While a small proportion of taxa displayed a significant pattern in regards to decay status of the host log, many bacterial taxa followed a stochastic distribution. Changes in the water availability and chemical composition of standing dead and downed trees and soil were strongly coupled with shifts in bacterial communities. Nitrogen was a major driver of succession and nitrogen-fixing taxa of the order Rhizobiales were abundant early in decomposition. Recently downed logs shared 65% of their bacterial abundance with the microbiomes of standing dead trees while only sharing 16% with soil. As decay proceeds, bacterial communities appear to respond less to shifting resource availability and more to interspecific bacterial interactions - we report an increase in both the proportion (+9.3%) and the intensity (+62.3%) of interspecific interactions in later stages of decomposition, suggesting the emergence of a more complex community structure as wood decay progresses.
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Affiliation(s)
- Eiko E. Kuramae
- Department of Microbial Ecology, Netherlands Institute of Ecology, Wageningen, Netherlands
| | - Marcio F. A. Leite
- Department of Microbial Ecology, Netherlands Institute of Ecology, Wageningen, Netherlands
| | - Afnan K. A. Suleiman
- Department of Microbial Ecology, Netherlands Institute of Ecology, Wageningen, Netherlands
| | - Christopher M. Gough
- Department of Biology, Virginia Commonwealth University, Richmond, VA, United States
| | - Buck T. Castillo
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, United States
| | - Lewis Faller
- Department of Biology, Linfield College, McMinnville, OR, United States
| | - Rima B. Franklin
- Department of Biology, Virginia Commonwealth University, Richmond, VA, United States
| | - John Syring
- Department of Biology, Linfield College, McMinnville, OR, United States
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27
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To Fix or Not To Fix: Controls on Free-Living Nitrogen Fixation in the Rhizosphere. Appl Environ Microbiol 2019; 85:AEM.02546-18. [PMID: 30658971 DOI: 10.1128/aem.02546-18] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Free-living nitrogen fixation (FLNF) in the rhizosphere, or N fixation by heterotrophic bacteria living on/near root surfaces, is ubiquitous and a significant source of N in some terrestrial systems. FLNF is also of interest in crop production as an alternative to chemical fertilizer, potentially reducing production costs and ameliorating negative environmental impacts of fertilizer N additions. Despite this interest, a mechanistic understanding of controls (e.g., carbon, oxygen, nitrogen, and nutrient availability) on FLNF in the rhizosphere is lacking but necessary. FLNF is distinct from and occurs under more diverse and dynamic conditions than symbiotic N fixation; therefore, predicting FLNF rates and understanding controls on FLNF has proven difficult. This has led to large gaps in our understanding of FLNF, and studies aimed at identifying controls on FLNF are needed. Here, we provide a mechanistic overview of FLNF, including how various controls may influence FLNF in the rhizosphere in comparison with symbiotic N fixation occurring in plant nodules where environmental conditions are moderated by the plant. We apply this knowledge to a real-world example, the bioenergy crop switchgrass (Panicum virgatum), to provide context of how FLNF may function in a managed system. We also highlight future challenges to assessing FLNF and understanding how FLNF functions in the environment and significantly contributes to plant N availability and productivity.
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28
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Rico CM, Johnson MG, Marcus MA, Andersen CP. Shifts in N and δ 15N in wheat and barley exposed to cerium oxide nanoparticles. NANOIMPACT 2018; 11:156-163. [PMID: 30320238 PMCID: PMC6178835 DOI: 10.1016/j.impact.2018.08.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The effects of cerium oxide nanoparticles (CeO2-NPs) on 15N/14N ratio (δ15N) in wheat and barley were investigated. Seedlings were exposed to 0 and 500 mg CeO2-NPs/L (Ce-0 and Ce-500, respectively) in hydroponic suspension supplied with NH4NO3, NH4 +, or NO3 -. N uptake and δ15N discrimination (i.e. differences in δ15N of plant and δ15N of N source) were measured. Results showed that N content and 15N abundance decreased in wheat but increased in barley. Ce-500 only induced whole-plant δ15N discrimination (-1.48‰, P ≤ 0.10) with a simultaneous decrease (P ≤ 0.05) in whole-plant δ15N (-3.24‰) compared to Ce-0 (-2.74‰) in wheat in NH4 +. Ce-500 decreased (P ≤ 0.01) root δ15N of wheat in NH4NO3 and NH4 + (3.23 and -2.25‰, respectively) compared to Ce-0 (4.96 and -1.27‰, respectively), but increased (P ≤ 0.05) root δ15N of wheat in NO3 - (3.27‰) compared to Ce-0 (2.60‰). Synchrotron micro-XRF revealed the presence of CeO2-NPs in shoots of wheat and barley regardless of N source. Although the longer-term consequences of CeO2-NP exposure on N uptake and metabolism are unknown, the results clearly show the potential for ENMs to interfere with plant metabolism of critical plant nutrients such as N even when toxicity is not observed.
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Affiliation(s)
- Cyren M. Rico
- National Research Council, Research Associateship Program, 500 Fifth Street, NW, Washington, DC 20001, USA
- US Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Western Ecology Division, 200 SW 35th St., Corvallis, OR 97333, USA
- Missouri State University, Department of Chemistry, 901 S National Ave., Springfield, MO 65897, USA
| | - Mark G. Johnson
- US Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Western Ecology Division, 200 SW 35th St., Corvallis, OR 97333, USA
| | - Matthew A. Marcus
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Christian P. Andersen
- US Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Western Ecology Division, 200 SW 35th St., Corvallis, OR 97333, USA
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29
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Chalk PM, Craswell ET. An overview of the role and significance of 15N methodologies in quantifying biological N2 fixation (BNF) and BNF dynamics in agro-ecosystems. Symbiosis 2017. [DOI: 10.1007/s13199-017-0526-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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30
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8000-year monsoonal record from Himalaya revealing reinforcement of tropical and global climate systems since mid-Holocene. Sci Rep 2017; 7:14515. [PMID: 29109454 PMCID: PMC5674060 DOI: 10.1038/s41598-017-15143-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 10/19/2017] [Indexed: 11/08/2022] Open
Abstract
We provide the first continuous Indian Summer Monsoon (ISM) climate record for the higher Himalayas (Kedarnath, India) by analyzing a 14C-dated peat sequence covering the last ~8000 years, with ~50 years temporal resolution. The ISM variability inferred using various proxies reveal striking similarity with the Greenland ice core (GISP2) temperature record and rapid denitrification changes recorded in the sediments off Peru. The Kedarnath record provides compelling evidence for a reorganization of the global climate system taking place at ~5.5 ka BP possibly after sea level stabilization and the advent of inter-annual climate variability governed by the modern ENSO phenomenon. The ISM record also captures warm-wet and cold-dry conditions during the Medieval Climate Anomaly and Little Ice Age, respectively.
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31
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Ekandjo LK, Ruppel S, Remus R, Witzel K, Patz S, Becker Y. Site-directed mutagenesis to deactivate two nitrogenase isozymes of Kosakonia radicincitans DSM16656 T. Can J Microbiol 2017; 64:97-106. [PMID: 29059532 DOI: 10.1139/cjm-2017-0532] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Biological nitrogen fixation (BNF) is considered one of the key plant-growth-promoting (PGP) factors for diazotrophic organisms. Whether the iron and iron-molybdenum nitrogenases of Kosakonia radicincitans contribute to its PGP effect is yet to be proven. Hence, for the first time, we conducted site-directed mutagenesis in K. radicincitans to knock out anfH and (or) nifH as a mean to deactivate BNF in this strain. We used 15N2-labeled air to trace BNF activities in ΔanfH, ΔnifH, and ΔanfHΔnifH mutants. Assessing bacterial growth, nitrogen content, and 15N incorporation revealed that BNF is impaired in K. radicincitans DSM16656T ΔnifH and ΔanfHΔnifH. However, we detected no significant contribution of the Fe nitrogenase to biological dinitrogen assimilation under our pure bacterial culture experimental conditions. Such nondiazotrophic K. radicincitans DSM16656T mutants represent excellent tools for investigating nitrogen nutrition in K. radicincitans-inoculated plants.
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Affiliation(s)
- Lempie K Ekandjo
- a Leibniz Institute of Vegetable and Ornamental Crops, Theodor-Echtermeyer-Weg 1, 14979 Groβbeeren, Germany
| | - Silke Ruppel
- a Leibniz Institute of Vegetable and Ornamental Crops, Theodor-Echtermeyer-Weg 1, 14979 Groβbeeren, Germany
| | - Rainer Remus
- b Leibniz Centre for Agricultural Landscape Research, Eberswalder Straβe 84, 15374 Müncheberg, Germany
| | - Katja Witzel
- a Leibniz Institute of Vegetable and Ornamental Crops, Theodor-Echtermeyer-Weg 1, 14979 Groβbeeren, Germany
| | - Sascha Patz
- a Leibniz Institute of Vegetable and Ornamental Crops, Theodor-Echtermeyer-Weg 1, 14979 Groβbeeren, Germany
| | - Yvonne Becker
- a Leibniz Institute of Vegetable and Ornamental Crops, Theodor-Echtermeyer-Weg 1, 14979 Groβbeeren, Germany
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32
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Keet JH, Ellis AG, Hui C, Le Roux JJ. Legume-rhizobium symbiotic promiscuity and effectiveness do not affect plant invasiveness. ANNALS OF BOTANY 2017; 119:1319-1331. [PMID: 28369229 PMCID: PMC5604570 DOI: 10.1093/aob/mcx028] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Accepted: 02/22/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND AND AIMS The ability to fix atmospheric nitrogen is thought to play an important role in the invasion success of legumes. Interactions between legumes and nitrogen-fixing bacteria (rhizobia) span a continuum of specialization, and promiscuous legumes are thought to have higher chances of forming effective symbioses in novel ranges. Using Australian Acacia species in South Africa, it was hypothesized that widespread and highly invasive species will be more generalist in their rhizobial symbiotic requirements and more effective in fixing atmospheric nitrogen compared with localized and less invasive species. METHODS To test these hypotheses, eight localized and 11 widespread acacias were examined using next-generation sequencing data for the nodulation gene, nodC , to compare the identity, species richness, diversity and compositional similarity of rhizobia associated with these acacias. Stable isotope analysis was also used to determine levels of nitrogen obtained from the atmosphere via symbiotic nitrogen fixation. KEY RESULTS No differences were found in richness, diversity and community composition between localized and widespread acacias. Similarly, widespread and localized acacias did not differ in their ability to fix atmospheric nitrogen. However, for some species by site comparisons, significant differences in δ15N isotopic signatures were found, indicating differential symbiotic effectiveness between these species at specific localities. CONCLUSIONS Overall, the results support recent findings that root nodule rhizobial diversity and community composition do not differ between acacias that vary in their invasiveness. Differential invasiveness of acacias in South Africa is probably linked to attributes such as differences in propagule pressure, reasons for (e.g. forestry vs. ornamental) and extent of, plantings in the country.
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Affiliation(s)
- Jan-Hendrik Keet
- Department of Botany and Zoology, Stellenbosch University, Matieland 7602, South Africa
| | - Allan G. Ellis
- Department of Botany and Zoology, Stellenbosch University, Matieland 7602, South Africa
| | - Cang Hui
- Centre for Invasion Biology, Department of Mathematical Sciences, Stellenbosch University, Matieland 7602, South Africa
- Mathematical and Physical Biosciences, African Institute for Mathematical Sciences, Cape Town 7945, South Africa
| | - Johannes J. Le Roux
- Department of Botany and Zoology, Stellenbosch University, Matieland 7602, South Africa
- Centre for Invasion Biology, Department of Mathematical Sciences, Stellenbosch University, Matieland 7602, South Africa
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33
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Jochum T, Fastnacht A, Trumbore SE, Popp J, Frosch T. Direct Raman Spectroscopic Measurements of Biological Nitrogen Fixation under Natural Conditions: An Analytical Approach for Studying Nitrogenase Activity. Anal Chem 2016; 89:1117-1122. [PMID: 28043118 DOI: 10.1021/acs.analchem.6b03101] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Biological N2 fixation is a major input of bioavailable nitrogen, which represents the most frequent factor limiting the agricultural production throughout the world. Especially, the symbiotic association between legumes and Rhizobium bacteria can provide substantial amounts of nitrogen (N) and reduce the need for industrial fertilizers. Despite its importance in the global N cycle, rates of biological nitrogen fixation have proven difficult to quantify. In this work, we propose and demonstrate a simple analytical approach to measure biological N2 fixation rates directly without a proxy or isotopic labeling. We determined a mean N2 fixation rate of 78 ± 5 μmol N2 (g dry weight nodule)-1 h-1 of a Medicago sativa-Rhizobium consortium by continuously analyzing the amount of atmospheric N2 in static environmental chambers with Raman gas spectroscopy. By simultaneously analyzing the CO2 uptake and photosynthetic plant activity, we think that a minimum CO2 mixing ratio might be needed for natural N2 fixation and only used the time interval above this minimum CO2 mixing ratio for N2 fixation rate calculations. The proposed approach relies only on noninvasive measurements of the gas phase and, given its simplicity, indicates the potential to estimate biological nitrogen fixation of legume symbioses not only in laboratory experiments. The same methods can presumably also be used to detect N2 fluxes by denitrification from ecosystems to the atmosphere.
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Affiliation(s)
- Tobias Jochum
- Leibniz Institute of Photonic Technology , 07745 Jena, Germany
| | - Agnes Fastnacht
- Max Planck Institute for Biogeochemistry , 07745 Jena, Germany
| | | | - Jürgen Popp
- Leibniz Institute of Photonic Technology , 07745 Jena, Germany.,Institute of Physical Chemistry and Abbe Center of Photonics , 07745 Jena, Germany
| | - Torsten Frosch
- Leibniz Institute of Photonic Technology , 07745 Jena, Germany.,Institute of Physical Chemistry and Abbe Center of Photonics , 07745 Jena, Germany
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34
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Ulm F, Hellmann C, Cruz C, Máguas C. N/P imbalance as a key driver for the invasion of oligotrophic dune systems by a woody legume. OIKOS 2016. [DOI: 10.1111/oik.03810] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Florian Ulm
- Faculdade de Ciencias da Universidade de Lisboa, Centre for Ecology, Evolution and Environmental Changes; Campo Grande, C2 PT-1749-016 Lisbon Portugal
| | - Christine Hellmann
- Experimental and Systems Ecology; Univ. of Bielefeld; Bielefeld Germany
- Dept of Ecosystem Physiology; Univ. of Freiburg; Freiburg Germany
| | - Cristina Cruz
- Faculdade de Ciencias da Universidade de Lisboa, Centre for Ecology, Evolution and Environmental Changes; Campo Grande, C2 PT-1749-016 Lisbon Portugal
| | - Cristina Máguas
- Faculdade de Ciencias da Universidade de Lisboa, Centre for Ecology, Evolution and Environmental Changes; Campo Grande, C2 PT-1749-016 Lisbon Portugal
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Lightfoot E, Przelomska N, Craven M, O Connell TC, He L, Hunt HV, Jones MK. Intraspecific carbon and nitrogen isotopic variability in foxtail millet (Setaria italica). RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30:1475-1487. [PMID: 27321835 DOI: 10.1002/rcm.7583] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 04/06/2016] [Accepted: 04/07/2016] [Indexed: 06/06/2023]
Abstract
RATIONALE Isotopic palaeodietary studies generally focus on bone collagen from human and/or animal remains. While plant remains are rarely analysed, it is known that plant isotope values can vary as a result of numerous factors, including soil conditions, the environment and type of plant. The millets were important food crops in prehistoric Eurasia, yet little is known about the isotopic differences within millet species. METHODS Here we compare the stable isotope ratios within and between Setaria italica plants grown in a controlled environment chamber. Using homogenised samples, we compare carbon isotope ratios of leaves and grains, and nitrogen isotope ratios of grains, from 29 accessions of Setaria italica. RESULTS We find significant isotopic variability within single leaves and panicles, and between leaves and panicles within the same plant, which must be considered when undertaking plant isotope studies. We find that the leaves and grains from the different accessions have a ca 2‰ range in δ(13) C values, while the nitrogen isotope values in the grains have a ca 6‰ range. We also find an average offset of 0.9‰ between leaves and grains in their δ(13) C values. CONCLUSIONS The variation found is large enough to have archaeological implications and within- and between-plant isotope variability should be considered in isotope studies. The range in δ(15) N values is particularly significant as it is larger than the typical values quoted for a trophic level enrichment, and as such may lead to erroneous interpretations of the amount of animal protein in human or animal diets. It is therefore necessary to account for the variability in plant stable isotope values during palaeodietary reconstructions. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Emma Lightfoot
- McDonald Institute for Archaeological Research, University of Cambridge, Downing Street, Cambridge, CB2 3ER, UK
| | - Natalia Przelomska
- Department of Archaeology and Anthropology, University of Cambridge, Downing Street, Cambridge, CB2 3DZ, UK
| | - Martha Craven
- Department of Archaeology and Anthropology, University of Cambridge, Downing Street, Cambridge, CB2 3DZ, UK
| | - Tamsin C O Connell
- Department of Archaeology and Anthropology, University of Cambridge, Downing Street, Cambridge, CB2 3DZ, UK
| | - Lu He
- College of Agriculture, Shanxi Agricultural University, Taigu, 030801, China
| | - Harriet V Hunt
- McDonald Institute for Archaeological Research, University of Cambridge, Downing Street, Cambridge, CB2 3ER, UK
| | - Martin K Jones
- Department of Archaeology and Anthropology, University of Cambridge, Downing Street, Cambridge, CB2 3DZ, UK
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Chalk PM. The strategic role of 15N in quantifying the contribution of endophytic N2 fixation to the N nutrition of non-legumes. Symbiosis 2016. [DOI: 10.1007/s13199-016-0397-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Minamisawa K, Imaizumi-Anraku H, Bao Z, Shinoda R, Okubo T, Ikeda S. Are Symbiotic Methanotrophs Key Microbes for N Acquisition in Paddy Rice Root? Microbes Environ 2016; 31:4-10. [PMID: 26960961 PMCID: PMC4791114 DOI: 10.1264/jsme2.me15180] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The relationships between biogeochemical processes and microbial functions in rice (Oryza sativa) paddies have been the focus of a large number of studies. A mechanistic understanding of methane–nitrogen (CH4–N) cycle interactions is a key unresolved issue in research on rice paddies. This minireview is an opinion paper for highlighting the mechanisms underlying the interactions between biogeochemical processes and plant-associated microbes based on recent metagenomic, metaproteomic, and isotope analyses. A rice symbiotic gene, relevant to rhizobial nodulation and mycorrhization in plants, likely accommodates diazotrophic methanotrophs or the associated bacterial community in root tissues under low-N fertilizer management, which may permit rice plants to acquire N via N2 fixation. The amount of N fixed in rice roots was previously estimated to be approximately 12% of plant N based on measurements of 15N natural abundance in a paddy field experiment. Community analyses also indicate that methanotroph populations in rice roots are susceptible to environmental conditions such as the microclimate of rice paddies. Therefore, CH4 oxidation by methanotrophs is a driving force in shaping bacterial communities in rice roots grown in CH4-rich environments. Based on these findings, we propose a hypothesis with unanswered questions to describe the interplay between rice plants, root microbiomes, and their biogeochemical functions (CH4 oxidation and N2 fixation).
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Influence of Rhizobia Inoculation on Biomass Gain and Tissue Nitrogen Content of Leucaena leucocephala Seedlings under Drought. FORESTS 2015. [DOI: 10.3390/f6103686] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Ariz I, Cruz C, Neves T, Irigoyen JJ, Garcia-Olaverri C, Nogués S, Aparicio-Tejo PM, Aranjuelo I. Leaf δ(15)N as a physiological indicator of the responsiveness of N2-fixing alfalfa plants to elevated [CO2], temperature and low water availability. FRONTIERS IN PLANT SCIENCE 2015; 6:574. [PMID: 26322051 PMCID: PMC4531240 DOI: 10.3389/fpls.2015.00574] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 07/13/2015] [Indexed: 05/23/2023]
Abstract
The natural (15)N/(14)N isotope composition (δ(15)N) of a tissue is a consequence of its N source and N physiological mechanisms in response to the environment. It could potentially be used as a tracer of N metabolism in plants under changing environmental conditions, where primary N metabolism may be complex, and losses and gains of N fluctuate over time. In order to test the utility of δ(15)N as an indicator of plant N status in N2-fixing plants grown under various environmental conditions, alfalfa (Medicago sativa L.) plants were subjected to distinct conditions of [CO2] (400 vs. 700 μmol mol(-1)), temperature (ambient vs. ambient +4°C) and water availability (fully watered vs. water deficiency-WD). As expected, increased [CO2] and temperature stimulated photosynthetic rates and plant growth, whereas these parameters were negatively affected by WD. The determination of δ(15)N in leaves, stems, roots, and nodules showed that leaves were the most representative organs of the plant response to increased [CO2] and WD. Depletion of heavier N isotopes in plants grown under higher [CO2] and WD conditions reflected decreased transpiration rates, but could also be related to a higher N demand in leaves, as suggested by the decreased leaf N and total soluble protein (TSP) contents detected at 700 μmol mol(-1) [CO2] and WD conditions. In summary, leaf δ(15)N provides relevant information integrating parameters which condition plant responsiveness (e.g., photosynthesis, TSP, N demand, and water transpiration) to environmental conditions.
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Affiliation(s)
- Idoia Ariz
- Faculdade de Ciências, Centro Ecologia Evolução e Alterações Ambientais, Universidade de LisboaLisboa, Portugal
| | - Cristina Cruz
- Faculdade de Ciências, Centro Ecologia Evolução e Alterações Ambientais, Universidade de LisboaLisboa, Portugal
| | - Tomé Neves
- Faculdade de Ciências, Centro Ecologia Evolução e Alterações Ambientais, Universidade de LisboaLisboa, Portugal
| | - Juan J. Irigoyen
- Grupo de Fisiología del Estrés en Plantas, Departamento de Biología Ambiental, Unidad Asociada al CSIC, EEAD, Zaragoza e ICVVLogroño, Spain
| | - Carmen Garcia-Olaverri
- Departamento de Estadística e Investigación Operativa, Universidad Pública de NavarraPamplona, Spain
| | - Salvador Nogués
- Departamento de Biología Vegetal, Facultat de Biologia, Universidad de BarcelonaBarcelona, Spain
| | - Pedro M. Aparicio-Tejo
- Departamento de Ciencias del Medio Natural, Universidad Pública de NavarraPamplona, Spain
| | - Iker Aranjuelo
- Plant Biology and Ecology Department, Science and Technology Faculty, University of the Basque CountryLeioa, Spain
- Instituto de Agrobiotecnología (IdAB), Universidad Pública de Navarra-CSIC-Gobierno de NavarraMutilva Baja, Spain
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Nygren P, Leblanc HA. Dinitrogen fixation by legume shade trees and direct transfer of fixed N to associated cacao in a tropical agroforestry system. TREE PHYSIOLOGY 2015; 35:134-147. [PMID: 25618898 DOI: 10.1093/treephys/tpu116] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Natural abundance of (15)N (δ (15)N) was determined in bulk soil, rhizospheric soil and vegetation in an organically managed cacao (Theobroma cacao L.) plantation with Inga edulis Mart. legume trees (inga) as the principal shade for studying the nitrogen (N) cycle in the system. Cacao without contact with legumes in an adjacent plantation was used as the reference for N2 fixation and direct N transfer calculations. Bulk and rhizospheric soils contained 72 and 20%, respectively, of whole- system N. No vegetation effect on δ (15)N in rhizospheric soil was detected, probably due to the high native soil N pool. Fine roots of the cacaos associated with inga contained ∼35% of N fixed from the atmosphere (Nf) out of the total N. Leaves of all species had significantly higher δ (15)N than fine roots. Twenty percent of system Nf was found in cacao suggesting direct N transfer from inga via a common mycelial network of mycorrhizal fungi or recycling of N-rich root exudates of inga. Inga had accumulated 98 kg [Nf] ha(-1) during the 14-year history of the plantation. The conservative estimate of current N2 fixation rate was 41 kg [Nf] ha(-1) year(-1) based on inga biomass only and 50 kg [Nf] ha(-1) year(-1) based on inga and associated trees.
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Affiliation(s)
- Pekka Nygren
- Department of Forest Science PO Box 27, 00014 University of Helsinki Finland Current address: Finnish Society of Forest Science, PO Box 18, 01301 Vantaa Finland
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Schmidt HL, Robins RJ, Werner RA. Multi-factorial in vivo stable isotope fractionation: causes, correlations, consequences and applications. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2015; 51:155-199. [PMID: 25894429 DOI: 10.1080/10256016.2015.1014355] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Many physical and chemical processes in living systems are accompanied by isotope fractionation on H, C, N, O and S. Although kinetic or thermodynamic isotope effects are always the basis, their in vivo manifestation is often modulated by secondary influences. These include metabolic branching events or metabolite channeling, metabolite pool sizes, reaction mechanisms, anatomical properties and compartmentation of plants and animals, and climatological or environmental conditions. In the present contribution, the fundamentals of isotope effects and their manifestation under in vivo conditions are outlined. The knowledge about and the understanding of these interferences provide a potent tool for the reconstruction of physiological events in plants and animals, their geographical origin, the history of bulk biomass and the biosynthesis of defined representatives. It allows the use of isotope characteristics of biomass for the elucidation of biochemical pathways and reaction mechanisms and for the reconstruction of climatic, physiological, ecological and environmental conditions during biosynthesis. Thus, it can be used for the origin and authenticity control of food, the study of ecosystems and animal physiology, the reconstruction of present and prehistoric nutrition chains and paleaoclimatological conditions. This is demonstrated by the outline of fundamental and application-orientated examples for all bio-elements. The aim of the review is to inform (advanced) students from various disciplines about the whole potential and the scope of stable isotope characteristics and fractionations and to provide them with a comprehensive introduction to the literature on fundamental aspects and applications.
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Affiliation(s)
- Hanns-Ludwig Schmidt
- a Lehrstuhl für Biologische Chemie , Technische Universität München , Freising-Weihenstephan, Germany
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