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Mitchell RL, Kenrick P, Pressel S, Duckett J, Strullu-Derrien C, Davies N, McMahon WJ, Summerfield R. Terrestrial surface stabilisation by modern analogues of the earliest land plants: A multi-dimensional imaging study. GEOBIOLOGY 2023; 21:454-473. [PMID: 36779552 DOI: 10.1111/gbi.12546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 12/23/2022] [Accepted: 01/05/2023] [Indexed: 06/13/2023]
Abstract
The evolution of the first plant-based terrestrial ecosystems in the early Palaeozoic had a profound effect on the development of soils, the architecture of sedimentary systems, and shifts in global biogeochemical cycles. In part, this was due to the evolution of complex below-ground (root-like) anchorage systems in plants, which expanded and promoted plant-mineral interactions, weathering, and resulting surface sediment stabilisation. However, little is understood about how these micro-scale processes occurred, because of a lack of in situ plant fossils in sedimentary rocks/palaeosols that exhibit these interactions. Some modern plants (e.g., liverworts, mosses, lycophytes) share key features with the earliest land plants; these include uni- or multicellular rhizoid-like anchorage systems or simple roots, and the ability to develop below-ground networks through prostrate axes, and intimate associations with fungi, making them suitable analogues. Here, we investigated cryptogamic ground covers in Iceland and New Zealand to better understand these interactions, and how they initiate the sediment stabilisation process. We employed multi-dimensional and multi-scale imaging, including scanning electron microscopy (SEM) and X-ray Computed Tomography (μCT) of non-vascular liverworts (Haplomitriopsida and complex thalloids) and mosses, with additional imaging of vascular lycopods. We find that plants interact with their substrate in multiple ways, including: (1) through the development of extensive surface coverings as mats; (2) entrapment of sediment grains within and between networks of rhizoids; (3) grain entwining and adherence by rhizoids, through mucilage secretions, biofilm-like envelopment of thalli on surface grains; and (4) through grain entrapment within upright 'leafy' structures. Significantly, μCT imaging allows us to ascertain that rhizoids are the main method for entrapment and stabilisation of soil grains in the thalloid liverworts. This information provides us with details of how the earliest land plants may have significantly influenced early Palaeozoic sedimentary system architectures, promoted in situ weathering and proto-soil development, and how these interactions diversified over time with the evolution of new plant organ systems. Further, this study highlights the importance of cryptogamic organisms in the early stages of sediment stabilisation and soil formation today.
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Affiliation(s)
- Ria L Mitchell
- Science Group, The Natural History Museum, London, UK
- Sheffield Tomography Centre (STC), Kroto Research Institute, The University of Sheffield, Sheffield, UK
| | - Paul Kenrick
- Science Group, The Natural History Museum, London, UK
| | | | - Jeff Duckett
- Science Group, The Natural History Museum, London, UK
| | - Christine Strullu-Derrien
- Science Group, The Natural History Museum, London, UK
- Institut de Systématique, Evolution, Biodiversité (ISYEB), UMR7205, Muséum National d'Histoire naturelle, Sorbonne Université, CNRS, Paris, France
| | - Neil Davies
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
| | - William J McMahon
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
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Hawkins HJ, Cargill RIM, Van Nuland ME, Hagen SC, Field KJ, Sheldrake M, Soudzilovskaia NA, Kiers ET. Mycorrhizal mycelium as a global carbon pool. Curr Biol 2023; 33:R560-R573. [PMID: 37279689 DOI: 10.1016/j.cub.2023.02.027] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
For more than 400 million years, mycorrhizal fungi and plants have formed partnerships that are crucial to the emergence and functioning of global ecosystems. The importance of these symbiotic fungi for plant nutrition is well established. However, the role of mycorrhizal fungi in transporting carbon into soil systems on a global scale remains under-explored. This is surprising given that ∼75% of terrestrial carbon is stored belowground and mycorrhizal fungi are stationed at a key entry point of carbon into soil food webs. Here, we analyze nearly 200 datasets to provide the first global quantitative estimates of carbon allocation from plants to the mycelium of mycorrhizal fungi. We estimate that global plant communities allocate 3.93 Gt CO2e per year to arbuscular mycorrhizal fungi, 9.07 Gt CO2e per year to ectomycorrhizal fungi, and 0.12 Gt CO2e per year to ericoid mycorrhizal fungi. Based on this estimate, 13.12 Gt of CO2e fixed by terrestrial plants is, at least temporarily, allocated to the underground mycelium of mycorrhizal fungi per year, equating to ∼36% of current annual CO2 emissions from fossil fuels. We explore the mechanisms by which mycorrhizal fungi affect soil carbon pools and identify approaches to increase our understanding of global carbon fluxes via plant-fungal pathways. Our estimates, although based on the best available evidence, are imperfect and should be interpreted with caution. Nonetheless, our estimations are conservative, and we argue that this work confirms the significant contribution made by mycorrhizal associations to global carbon dynamics. Our findings should motivate their inclusion both within global climate and carbon cycling models, and within conservation policy and practice.
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Affiliation(s)
- Heidi-Jayne Hawkins
- Department of Biological Sciences, University of Cape Town, Cape Town 7701, South Africa; Conservation International, Forrest House, Belmont Park, Cape Town 7700, South Africa.
| | - Rachael I M Cargill
- Amsterdam Institute for Life and Environment, Vrije Universiteit, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands; AMOLF, Science Park 102, Amsterdam, The Netherlands
| | - Michael E Van Nuland
- Amsterdam Institute for Life and Environment, Vrije Universiteit, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands; Society for the Protection of Underground Networks, SPUN, 3500 South DuPont Highway, Dover, DE 19901, USA
| | | | - Katie J Field
- Plants, Photosynthesis and Soil, School of Biosciences, The University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Merlin Sheldrake
- Amsterdam Institute for Life and Environment, Vrije Universiteit, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands; Society for the Protection of Underground Networks, SPUN, 3500 South DuPont Highway, Dover, DE 19901, USA
| | | | - E Toby Kiers
- Amsterdam Institute for Life and Environment, Vrije Universiteit, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands; Society for the Protection of Underground Networks, SPUN, 3500 South DuPont Highway, Dover, DE 19901, USA
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Hoysted GA, Field KJ, Sinanaj B, Bell CA, Bidartondo MI, Pressel S. Direct nitrogen, phosphorus and carbon exchanges between Mucoromycotina 'fine root endophyte' fungi and a flowering plant in novel monoxenic cultures. THE NEW PHYTOLOGIST 2023; 238:70-79. [PMID: 36739554 PMCID: PMC10952891 DOI: 10.1111/nph.18630] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 11/15/2022] [Indexed: 06/18/2023]
Abstract
Most plants form mycorrhizal associations with mutualistic soil fungi. Through these partnerships, resources are exchanged including photosynthetically fixed carbon for fungal-acquired nutrients. Recently, it was shown that the diversity of associated fungi is greater than previously assumed, extending to Mucoromycotina fungi. These Mucoromycotina 'fine root endophytes' (MFRE) are widespread and generally co-colonise plant roots together with Glomeromycotina 'coarse' arbuscular mycorrhizal fungi (AMF). Until now, this co-occurrence has hindered the determination of the direct function of MFRE symbiosis. To overcome this major barrier, we developed new techniques for fungal isolation and culture and established the first monoxenic in vitro cultures of MFRE colonising a flowering plant, clover. Using radio- and stable-isotope tracers in these in vitro systems, we measured the transfer of 33 P, 15 N and 14 C between MFRE hyphae and the host plant. Our results provide the first unequivocal evidence that MFRE fungi are nutritional mutualists with a flowering plant by showing that clover gained both 15 N and 33 P tracers directly from fungus in exchange for plant-fixed C in the absence of other micro-organisms. Our findings and methods pave the way for a new era in mycorrhizal research, firmly establishing MFRE as both mycorrhizal and functionally important in terrestrial ecosystems.
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Affiliation(s)
- Grace A. Hoysted
- Plants, Photosynthesis and Soil, School of BioscienceUniversity of SheffieldSheffieldS10 2TNUK
| | - Katie J. Field
- Plants, Photosynthesis and Soil, School of BioscienceUniversity of SheffieldSheffieldS10 2TNUK
| | - Besiana Sinanaj
- Plants, Photosynthesis and Soil, School of BioscienceUniversity of SheffieldSheffieldS10 2TNUK
| | | | - Martin I. Bidartondo
- Department of Life SciencesImperial College LondonLondonSW7 2AZUK
- Department of Ecosystem StewardshipRoyal Botanic Gardens, KewRichmondTW9 3DSUK
| | - Silvia Pressel
- Department of Life SciencesNatural History MuseumLondonSW7 5BDUK
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Abstract
Recent human activity has profoundly transformed Earth biomes on a scale and at rates that are unprecedented. Given the central role of symbioses in ecosystem processes, functions, and services throughout the Earth biosphere, the impacts of human-driven change on symbioses are critical to understand. Symbioses are not merely collections of organisms, but co-evolved partners that arise from the synergistic combination and action of different genetic programs. They function with varying degrees of permanence and selection as emergent units with substantial potential for combinatorial and evolutionary innovation in both structure and function. Following an articulation of operational definitions of symbiosis and related concepts and characteristics of the Anthropocene, we outline a basic typology of anthropogenic change (AC) and a conceptual framework for how AC might mechanistically impact symbioses with select case examples to highlight our perspective. We discuss surprising connections between symbiosis and the Anthropocene, suggesting ways in which new symbioses could arise due to AC, how symbioses could be agents of ecosystem change, and how symbioses, broadly defined, of humans and “farmed” organisms may have launched the Anthropocene. We conclude with reflections on the robustness of symbioses to AC and our perspective on the importance of symbioses as ecosystem keystones and the need to tackle anthropogenic challenges as wise and humble stewards embedded within the system.
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Affiliation(s)
- Erik F Y Hom
- Department of Biology and Center for Biodiversity and Conservation Research, University of Mississippi, University, MS 38677 USA
| | - Alexandra S Penn
- Department of Sociology and Centre for Evaluation of Complexity Across the Nexus, University of Surrey, Guildford, Surrey, GU2 7XH UK
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Mitchell RL, Davies P, Kenrick P, Volkenandt T, Pleydell-Pearce C, Johnston R. Correlative Microscopy: a tool for understanding soil weathering in modern analogues of early terrestrial biospheres. Sci Rep 2021; 11:12736. [PMID: 34140576 PMCID: PMC8211647 DOI: 10.1038/s41598-021-92184-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 05/27/2021] [Indexed: 02/05/2023] Open
Abstract
Correlative imaging provides a method of investigating complex systems by combining analytical (chemistry) and imaging (tomography) information across dimensions (2D-3D) and scales (centimetres-nanometres). We studied weathering processes in a modern cryptogamic ground cover from Iceland, containing early colonizing, and evolutionary ancient, communities of mosses, lichens, fungi, and bacteria. Targeted multi-scale X-ray Microscopy of a grain in-situ within a soil core revealed networks of surficial and internal features (tunnels) originating from organic-rich surface holes. Further targeted 2D grain characterisation by optical microscopy (OM), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (SEM-EDS), following an intermediate manual correlative preparation step, revealed Fe-rich nodules within the tunnels. Finally, nanotomographic imaging by focussed ion beam microscopy (FIB-SEM) revealed coccoid and filamentous-like structures within subsurface tunnels, as well as accumulations of Fe and S in grain surface crusts, which may represent a biological rock varnish/glaze. We attribute these features to biological processes. This work highlights the advantages and novelty of the correlative imaging approach, across scales, dimensions, and modes, to investigate biological weathering processes. Further, we demonstrate correlative microscopy as a means of identifying fingerprints of biological communities, which could be used in the geologic rock record and on extra-terrestrial bodies.
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Affiliation(s)
- R. L. Mitchell
- grid.4827.90000 0001 0658 8800Advanced Imaging of Materials (AIM) Facility, College of Engineering, Bay Campus, Swansea University, Swansea, SA1 8EN UK ,grid.35937.3b0000 0001 2270 9879Earth Sciences Department, The Natural History Museum, Cromwell Road, London, SW7 5BD UK ,grid.11835.3e0000 0004 1936 9262Sheffield Tomography Centre (STC), The University of Sheffield, North Campus, Broad Lane, Sheffield, S3 7HQ UK
| | - P. Davies
- grid.4827.90000 0001 0658 8800Advanced Imaging of Materials (AIM) Facility, College of Engineering, Bay Campus, Swansea University, Swansea, SA1 8EN UK
| | - P. Kenrick
- grid.35937.3b0000 0001 2270 9879Earth Sciences Department, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - T. Volkenandt
- grid.424549.a0000 0004 0379 7801Carl Zeiss Microscopy GmbH, Carl-Zeiss-Straße 22, 73447 Oberkochen, Germany
| | - C. Pleydell-Pearce
- grid.4827.90000 0001 0658 8800Advanced Imaging of Materials (AIM) Facility, College of Engineering, Bay Campus, Swansea University, Swansea, SA1 8EN UK
| | - R. Johnston
- grid.4827.90000 0001 0658 8800Advanced Imaging of Materials (AIM) Facility, College of Engineering, Bay Campus, Swansea University, Swansea, SA1 8EN UK
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Abstract
Phosphorous is important for life but often limiting for plants. The symbiotic pathway of phosphate uptake via arbuscular mycorrhizal fungi (AMF) is evolutionarily ancient and today occurs in natural and agricultural ecosystems alike. Plants capable of this symbiosis can obtain up to all of the phosphate from symbiotic fungi, and this offers potential means to develop crops less dependent on unsustainable P fertilizers. Here, we review the mechanisms and insights gleaned from the fine-tuned signal exchanges that orchestrate the intimate mutualistic symbiosis between plants and AMF. As the currency of trade, nutrients have signaling functions beyond being the nutritional goal of mutualism. We propose that such signaling roles and metabolic reprogramming may represent commitments for a mutualistic symbiosis that act across the stages of symbiosis development.
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Affiliation(s)
- Chai Hao Chiu
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| | - Uta Paszkowski
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
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Field KJ, Pressel S. Unity in diversity: structural and functional insights into the ancient partnerships between plants and fungi. THE NEW PHYTOLOGIST 2018; 220:996-1011. [PMID: 29696662 DOI: 10.1111/nph.15158] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 03/06/2018] [Indexed: 05/16/2023]
Abstract
Contents Summary 996 I. Introduction 996 II. An ancient, and diverse, symbiosis 998 III. Structural diversity in ancient plant-fungal partnerships 1000 IV. Mycorrhizal unity in host plant nutrition 1002 V. Plant-to-fungus carbon transfer 1003 VI. From individuals to networks 1003 VII. Diverse responses of mycorrhizal functioning to dynamic environments 1006 VIII. Summary of future research direction 1007 Acknowledgements 1006 References 1006 SUMMARY: Mycorrhizal symbiosis is an ancient and widespread mutualism between plants and fungi that facilitated plant terrestrialisation > 500 million years ago, with key roles in ecosystem functioning at multiple scales. Central to the symbiosis is the bidirectional exchange of plant-fixed carbon for fungal-acquired nutrients. Within this unifying role of mycorrhizas, considerable diversity in structure and function reflects the diversity of the partners involved. Early diverging plants form mutualisms not only with arbuscular mycorrhizal Glomeromycotina fungi, but also with poorly characterised Mucoromycotina, which may also colonise the roots of 'higher' plants as fine root endophytes. Functional diversity in these symbioses depends on both fungal and plant life histories and is influenced by the environment. Recent studies have highlighted the roles of lipids/fatty acids in plant-to-fungus carbon transport and potential contributions of Glomeromycotina fungi to plant nitrogen nutrition. Together with emerging appreciation of mycorrhizal networks as multi-species resource-sharing systems, these insights are broadening our views on mycorrhizas and their roles in nutrient cycling. It is crucial that the diverse array of biotic and abiotic factors that together shape the dynamics of carbon-for-nutrient exchange between plants and fungi are integrated, in addition to embracing the unfolding and potentially key role of Mucoromycotina fungi in these processes.
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Affiliation(s)
- Katie J Field
- Centre for Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Silvia Pressel
- Department of Life Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, UK
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Edwards D, Kenrick P, Dolan L. History and contemporary significance of the Rhynie cherts-our earliest preserved terrestrial ecosystem. Philos Trans R Soc Lond B Biol Sci 2018; 373:rstb.2016.0489. [PMID: 29254954 DOI: 10.1098/rstb.2016.0489] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/25/2017] [Indexed: 01/03/2023] Open
Abstract
The Rhynie cherts Unit is a 407 million-year old geological site in Scotland that preserves the most ancient known land plant ecosystem, including associated animals, fungi, algae and bacteria. The quality of preservation is astonishing, and the initial description of several plants 100 years ago had a huge impact on botany. Subsequent discoveries provided unparalleled insights into early life on land. These include the earliest records of plant life cycles and fungal symbioses, the nature of soil microorganisms and the diversity of arthropods. Today the Rhynie chert (here including the Rhynie and Windyfield cherts) takes on new relevance, especially in relation to advances in the fields of developmental genetics and Earth systems science. New methods and analytical techniques also contribute to a better understanding of the environment and its organisms. Key discoveries are reviewed, focusing on the geology of the site, the organisms and the palaeoenvironments. The plants and their symbionts are of particular relevance to understanding the early evolution of the plant life cycle and the origins of fundamental organs and tissue systems. The Rhynie chert provides remarkable insights into the structure and interactions of early terrestrial communities, and it has a significant role to play in developing our understanding of their broader impact on Earth systems.This article is part of a discussion meeting issue 'The Rhynie cherts: our earliest terrestrial ecosystem revisited'.
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Affiliation(s)
- Dianne Edwards
- School of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3AT, UK
| | - Paul Kenrick
- Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Liam Dolan
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
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