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Duchesneau K, Defrenne CE, Petro C, Malhotra A, Moore JAM, Childs J, Hanson PJ, Iversen CM, Kostka JE. Responses of vascular plant fine roots and associated microbial communities to whole-ecosystem warming and elevated CO 2 in northern peatlands. THE NEW PHYTOLOGIST 2024; 242:1333-1347. [PMID: 38515239 DOI: 10.1111/nph.19690] [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: 09/28/2023] [Accepted: 02/16/2024] [Indexed: 03/23/2024]
Abstract
Warming and elevated CO2 (eCO2) are expected to facilitate vascular plant encroachment in peatlands. The rhizosphere, where microbial activity is fueled by root turnover and exudates, plays a crucial role in biogeochemical cycling, and will likely at least partially dictate the response of the belowground carbon cycle to climate changes. We leveraged the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment, to explore the effects of a whole-ecosystem warming gradient (+0°C to 9°C) and eCO2 on vascular plant fine roots and their associated microbes. We combined trait-based approaches with the profiling of fungal and prokaryote communities in plant roots and rhizospheres, through amplicon sequencing. Warming promoted self-reliance for resource uptake in trees and shrubs, while saprophytic fungi and putative chemoorganoheterotrophic bacteria utilizing plant-derived carbon substrates were favored in the root zone. Conversely, eCO2 promoted associations between trees and ectomycorrhizal fungi. Trees mostly associated with short-distance exploration-type fungi that preferentially use labile soil N. Additionally, eCO2 decreased the relative abundance of saprotrophs in tree roots. Our results indicate that plant fine-root trait variation is a crucial mechanism through which vascular plants in peatlands respond to climate change via their influence on microbial communities that regulate biogeochemical cycles.
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Affiliation(s)
- Katherine Duchesneau
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Camille E Defrenne
- College of Forest Resources and Environmental Science, Michigan Technological University, Houghton, MI, 49931, USA
| | - Caitlin Petro
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Avni Malhotra
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - Jessica A M Moore
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - Joanne Childs
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Paul J Hanson
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
- Climate Change Science Institute and Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Colleen M Iversen
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
- Climate Change Science Institute and Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Joel E Kostka
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
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2
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Journeaux KL, Boddy L, Rowland L, Hartley IP. A positive feedback to climate change: The effect of temperature on the respiration of key wood-decomposing fungi does not decline with time. GLOBAL CHANGE BIOLOGY 2024; 30:e17212. [PMID: 38450825 DOI: 10.1111/gcb.17212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 01/21/2024] [Accepted: 02/05/2024] [Indexed: 03/08/2024]
Abstract
Heterotrophic soil microorganisms are responsible for ~50% of the carbon dioxide released by respiration from the terrestrial biosphere each year. The respiratory response of soil microbial communities to warming, and the control mechanisms, remains uncertain, yet is critical to understanding the future land carbon (C)-climate feedback. Individuals of nine species of fungi decomposing wood were exposed to 90 days of cooling to evaluate the medium-term effect of temperature on respiration. Overall, the effect of temperature on respiration increased in the medium term, with no evidence of compensation. However, the increasing effect of temperature on respiration was lost after correcting for changes in biomass. These results indicate that C loss through respiration of wood-decomposing fungi will increase beyond the direct effects of temperature on respiration, potentially promoting greater C losses from terrestrial ecosystems and a positive feedback to climate change.
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Affiliation(s)
- Katie L Journeaux
- Geography, Faculty of Environment, Science and Economy, University of Exeter, Exeter, UK
| | - Lynne Boddy
- School of Biosciences, Cardiff University, Cardiff, UK
| | - Lucy Rowland
- Geography, Faculty of Environment, Science and Economy, University of Exeter, Exeter, UK
| | - Iain P Hartley
- Geography, Faculty of Environment, Science and Economy, University of Exeter, Exeter, UK
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3
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Liu C, Tian H, Gu X, Li N, Zhao X, Lei M, Alharbi H, Megharaj M, He W, Kuzyakov Y. Catalytic efficiency of soil enzymes explains temperature sensitivity: Insights from physiological theory. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 822:153365. [PMID: 35077802 DOI: 10.1016/j.scitotenv.2022.153365] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 01/17/2022] [Accepted: 01/19/2022] [Indexed: 06/14/2023]
Abstract
Soil enzymes are crucial for carbon and nutrient cycling and are highly sensitive to warming. Biochemical reaction rates increase with temperature according to the Arrhenius law, but changes in microbial physiology may partially counteract this warming-induced acceleration that leads enzymatic rates to deviate from Arrhenius law. Here, we attempt to reconcile disparate views on the enzyme responses to warming based on the Arrhenius law and physiological theory by enzyme catalytic efficiency. In this study, we tested the kinetic parameters of five key enzymes of C, N, and P cycling to warming (from 0 to 40 °C) in cropland soils originating from 5 different temperate zones. The soils were incubated for one month at 0, 10, 20, 30, and 40 °C (±0.5 °C) with 60% water holding capacity (WHC). The kinetic parameters were calculated and measured at a range of 4-methyumbelliferone (MUB)-substrate concentrations. We found that catalytic efficiency (Vmax/Km) of individual enzymes ranged from 0.05 to 27 s-1 between 0 and 40 °C. Maximum reaction rate (Vmax) increased with warming, while Vmax/Km of most enzymes remained stable by warming at low temperatures (up to 10 °C), and it raised from 20 to 40 °C. Most enzymes had lower substrate affinities (Km) and increased their efficiency with warming. Consistent with studies considering Arrhenius law solely, the temperature sensitivity (Q10) of Vmax decreased with warming. However, the Q10 of Vmax/Km displayed a lower value in the cold but a higher value in warmer temperature, which confirmed microbial adaptation based on physiological theory, consequently encouraging its linking with the Arrhenius law. Therefore, Arrhenius linked with physiological theory could correct explanation of enzyme activities by warming. Considering the microbial adaptation to temperature, the present predicted warming-induced acceleration of soil organic matter decomposition might be overestimated in cold and underestimated in warm environments.
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Affiliation(s)
- Chaoyang Liu
- College of Natural Resources and Environment, Northwest A&F University, Key Laboratory of Plant Nutrition and Agro-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China
| | - Haixia Tian
- College of Natural Resources and Environment, Northwest A&F University, Key Laboratory of Plant Nutrition and Agro-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China
| | - Xiaoyue Gu
- College of Natural Resources and Environment, Northwest A&F University, Key Laboratory of Plant Nutrition and Agro-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China
| | - Ni Li
- College of Natural Resources and Environment, Northwest A&F University, Key Laboratory of Plant Nutrition and Agro-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China
| | - Xiaoning Zhao
- School of Geographical Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Mei Lei
- Center for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Hattan Alharbi
- College of Food and Agriculture Sciences, King Saud University, Riyadh 11451, Saudi Arabia
| | - Mallavarapu Megharaj
- Global Centre for Environmental Remediation, Faculty of Science, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Wenxiang He
- College of Natural Resources and Environment, Northwest A&F University, Key Laboratory of Plant Nutrition and Agro-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, China.
| | - Yakov Kuzyakov
- Department of Soil Science of Temperate Ecosystems, Department of Agricultural Soil Science, University of Göttingen, Göttingen, Germany; Agro-Technological Institute, RUDN University, 117198 Moscow, Russia; Institute of Environmental Sciences, Kazan Federal University, 420049 Kazan, Russia
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4
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Auxier B, Czárán TL, Aanen DK. Modelling the consequences of the dikaryotic life cycle of mushroom-forming fungi on genomic conflict. eLife 2022; 11:75917. [PMID: 35441591 PMCID: PMC9084891 DOI: 10.7554/elife.75917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 04/14/2022] [Indexed: 11/21/2022] Open
Abstract
Generally, sexual organisms contain two haploid genomes, one from each parent, united in a single diploid nucleus of the zygote which links their fate during growth. A fascinating exception to this is Basidiomycete fungi, where the two haploid genomes remain separate in a dikaryon, retaining the option to fertilize subsequent monokaryons encountered. How the ensuing nuclear competition influences the balance of selection within and between individuals is largely unexplored. We test the consequences of the dikaryotic life cycle for mating success and mycelium-level fitness components. We assume a trade-off between mating fitness at the level of the haploid nucleus and fitness of the fungal mycelium. We show that the maintenance of fertilization potential by dikaryons leads to a higher proportion of fertilized monokaryons, but that the ensuing intradikaryon selection for increased nuclear mating fitness leads to reduced mycelium fitness relative to a diploid life cycle. However, this fitness reduction is lower compared to a hypothetical life cycle where dikaryons can also exchange nuclei. Prohibition of fusion between dikaryons therefore reduces the level of nuclear parasitism. The number of loci influencing fitness is an important determinant of the degree to which average mycelium-level fitness is reduced. The results of this study crucially hinge upon a trade-off between nucleus and mycelium-level fitness. We discuss the evidence for this assumption and the implications of an alternative that there is a positive relationship between nucleus and mycelium-level fitness.
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Affiliation(s)
- Benjamin Auxier
- Laboratory of Genetics, Wageningen University, Wageningen, Netherlands
| | | | - Duur K Aanen
- Laboratory of Genetics, Wageningen University, Wageningen, Netherlands
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Alster CJ, Allison SD, Johnson NG, Glassman SI, Treseder KK. Phenotypic plasticity of fungal traits in response to moisture and temperature. ISME COMMUNICATIONS 2021; 1:43. [PMID: 36740602 PMCID: PMC9723763 DOI: 10.1038/s43705-021-00045-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 07/13/2021] [Accepted: 07/23/2021] [Indexed: 02/07/2023]
Abstract
Phenotypic plasticity of traits is commonly measured in plants to improve understanding of organismal and ecosystem responses to climate change but is far less studied for microbes. Specifically, decomposer fungi are thought to display high levels of phenotypic plasticity and their functions have important implications for ecosystem dynamics. Assessing the phenotypic plasticity of fungal traits may therefore be important for predicting fungal community response to climate change. Here, we assess the phenotypic plasticity of 15 fungal isolates (12 species) from a Southern California grassland. Fungi were incubated on litter at five moisture levels (ranging from 4-50% water holding capacity) and at five temperatures (ranging from 4-36 °C). After incubation, fungal biomass and activities of four extracellular enzymes (cellobiohydrolase (CBH), β-glucosidase (BG), β-xylosidase (BX), and N-acetyl-β-D-glucosaminidase (NAG)) were measured. We used response surface methodology to determine how fungal phenotypic plasticity differs across the moisture-temperature gradient. We hypothesized that fungal biomass and extracellular enzyme activities would vary with moisture and temperature and that the shape of the response surface would vary between fungal isolates. We further hypothesized that more closely related fungi would show more similar response surfaces across the moisture-temperature gradient. In support of our hypotheses, we found that plasticity differed between fungi along the temperature gradient for fungal biomass and for all the extracellular enzyme activities. Plasticity also differed between fungi along the moisture gradient for BG activity. These differences appear to be caused by variation mainly at the moisture and temperature extremes. We also found that more closely related fungi had more similar extracellular enzymes activities at the highest temperature. Altogether, this evidence suggests that with global warming, fungal biodiversity may become increasingly important as functional traits tend to diverge along phylogenetic lines at higher temperatures.
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Affiliation(s)
- Charlotte J Alster
- Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA, USA.
- School of Science, University of Waikato, Hamilton, New Zealand.
| | - Steven D Allison
- Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA, USA
- Department of Earth System Science, University of California, Irvine, Irvine, CA, USA
| | - Nels G Johnson
- USDA Forest Service, Pacific Southwest Research Station, Albany, CA, USA
| | - Sydney I Glassman
- Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA, USA
- Department of Microbiology and Plant Pathology, University of California, Riverside, CA, USA
| | - Kathleen K Treseder
- Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA, USA
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6
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Romero-Olivares AL, Meléndrez-Carballo G, Lago-Lestón A, Treseder KK. Soil Metatranscriptomes Under Long-Term Experimental Warming and Drying: Fungi Allocate Resources to Cell Metabolic Maintenance Rather Than Decay. Front Microbiol 2019; 10:1914. [PMID: 31551941 PMCID: PMC6736569 DOI: 10.3389/fmicb.2019.01914] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 08/05/2019] [Indexed: 11/29/2022] Open
Abstract
Earth’s temperature is rising, and with this increase, fungal communities are responding and affecting soil carbon processes. At a long-term soil-warming experiment in a boreal forest in interior Alaska, warming and warming-associated drying alters the function of microbes, and thus, decomposition of carbon. But what genetic mechanisms and resource allocation strategies are behind these community shifts and soil carbon changes? Here, we evaluate fungal resource allocation efforts under long-term experimental warming (including associated drying) using soil metatranscriptomics. We profiled resource allocation efforts toward decomposition and cell metabolic maintenance, and we characterized community composition. We found that under the warming treatment, fungi allocate resources to cell metabolic maintenance at the expense of allocating resources to decomposition. In addition, we found that fungal orders that house taxa with stress-tolerant traits were more abundant under the warmed treatment compared to control conditions. Our results suggest that the warming treatment elicits an ecological tradeoff in resource allocation in the fungal communities, with potential to change ecosystem-scale carbon dynamics. Fungi preferentially invest in mechanisms that will ensure survival under warming and drying, such as cell metabolic maintenance, rather than in decomposition. Through metatranscriptomes, we provide mechanistic insight behind the response of fungi to climate change and consequences to soil carbon processes.
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Affiliation(s)
- Adriana L Romero-Olivares
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA, United States
| | - Germán Meléndrez-Carballo
- Department of Electronics and Telecommunications, Ensenada Center for Scientific Research and Higher Education, Ensenada, Mexico
| | - Asunción Lago-Lestón
- Department of Medical Innovation, Ensenada Center for Scientific Research and Higher Education, Ensenada, Mexico
| | - Kathleen K Treseder
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA, United States
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7
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Li J, Wang G, Mayes MA, Allison SD, Frey SD, Shi Z, Hu XM, Luo Y, Melillo JM. Reduced carbon use efficiency and increased microbial turnover with soil warming. GLOBAL CHANGE BIOLOGY 2019; 25:900-910. [PMID: 30417564 DOI: 10.1111/gcb.14517] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 08/23/2018] [Accepted: 10/19/2018] [Indexed: 05/25/2023]
Abstract
Global soil carbon (C) stocks are expected to decline with warming, and changes in microbial processes are key to this projection. However, warming responses of critical microbial parameters such as carbon use efficiency (CUE) and biomass turnover (rB) are not well understood. Here, we determine these parameters using a probabilistic inversion approach that integrates a microbial-enzyme model with 22 years of carbon cycling measurements at Harvard Forest. We find that increasing temperature reduces CUE but increases rB, and that two decades of soil warming increases the temperature sensitivities of CUE and rB. These temperature sensitivities, which are derived from decades-long field observations, contrast with values obtained from short-term laboratory experiments. We also show that long-term soil C flux and pool changes in response to warming are more dependent on the temperature sensitivity of CUE than that of rB. Using the inversion-derived parameters, we project that chronic soil warming at Harvard Forest over six decades will result in soil C gain of <1.0% on average (1st and 3rd quartiles: 3.0% loss and 10.5% gain) in the surface mineral horizon. Our results demonstrate that estimates of temperature sensitivity of microbial CUE and rB can be obtained and evaluated rigorously by integrating multidecadal datasets. This approach can potentially be applied in broader spatiotemporal scales to improve long-term projections of soil C feedbacks to climate warming.
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Affiliation(s)
- Jianwei Li
- Department of Agricultural and Environmental Sciences, Tennessee State University, Nashville, Tennessee
| | - Gangsheng Wang
- Environmental Sciences Division, Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, Tennessee
- Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma
| | - Melanie A Mayes
- Environmental Sciences Division, Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Steven D Allison
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California
- Department of Earth System Science, University of California, Irvine, California
| | - Serita D Frey
- Department of Natural Resources and the Environment, University of New Hampshire, Durham, New Hampshire
| | - Zheng Shi
- Center for Analysis and Prediction of Storms, School of Meteorology, University of Oklahoma, Norman, Oklahoma
| | - Xiao-Ming Hu
- Center for Analysis and Prediction of Storms, School of Meteorology, University of Oklahoma, Norman, Oklahoma
| | - Yiqi Luo
- Department of Biological Sciences, Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona
| | - Jerry M Melillo
- The Ecosystem Center, Marine Biological Laboratory, Woods Hole, Massachusetts
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