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Martignoni MM, Tyson RC, Kolodny O, Garnier J. Mutualism at the leading edge: insights into the eco-evolutionary dynamics of host-symbiont communities during range expansion. J Math Biol 2024; 88:24. [PMID: 38308102 DOI: 10.1007/s00285-023-02037-w] [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: 04/09/2023] [Revised: 09/04/2023] [Accepted: 12/14/2023] [Indexed: 02/04/2024]
Abstract
The evolution of mutualism between host and symbiont communities plays an essential role in maintaining ecosystem function and should therefore have a profound effect on their range expansion dynamics. In particular, the presence of mutualistic symbionts at the leading edge of a host-symbiont community should enhance its propagation in space. We develop a theoretical framework that captures the eco-evolutionary dynamics of host-symbiont communities, to investigate how the evolution of resource exchange may shape community structure during range expansion. We consider a community with symbionts that are mutualistic or parasitic to various degrees, where parasitic symbionts receive the same amount of resource from the host as mutualistic symbionts, but at a lower cost. The selective advantage of parasitic symbionts over mutualistic ones is increased with resource availability (i.e. with host density), promoting mutualism at the range edges, where host density is low, and parasitism at the population core, where host density is higher. This spatial selection also influences the speed of spread. We find that the host growth rate (which depends on the average benefit provided by the symbionts) is maximal at the range edges, where symbionts are more mutualistic, and that host-symbiont communities with high symbiont density at their core (e.g. resulting from more mutualistic hosts) spread faster into new territories. These results indicate that the expansion of host-symbiont communities is pulled by the hosts but pushed by the symbionts, in a unique push-pull dynamic where both the host and symbionts are active and tightly-linked players.
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Affiliation(s)
- Maria M Martignoni
- Department of Ecology, Evolution and Behavior, A. Silberman Institute of Life Sciences, Faculty of Sciences, Hebrew University of Jerusalem, Jerusalem, Israel.
| | - Rebecca C Tyson
- CMPS Department (Mathematics), University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Oren Kolodny
- Department of Ecology, Evolution and Behavior, A. Silberman Institute of Life Sciences, Faculty of Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Jimmy Garnier
- Laboratory of Mathematics, CNRS, Université Savoie-Mont Blanc, Université Grenoble Alpes, Chambery, France
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2
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Mohd-Radzman NA, Drapek C. Compartmentalisation: A strategy for optimising symbiosis and tradeoff management. PLANT, CELL & ENVIRONMENT 2023; 46:2998-3011. [PMID: 36717758 DOI: 10.1111/pce.14553] [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: 10/04/2022] [Revised: 01/19/2023] [Accepted: 01/26/2023] [Indexed: 06/18/2023]
Abstract
Plant root architecture is developmentally plastic in response to fluctuating nutrient levels in the soil. Part of this developmental plasticity is the formation of dedicated root cells and organs to host mutualistic symbionts. Structures like nitrogen-fixing nodules serve as alternative nutrient acquisition strategies during starvation conditions. Some root systems can also form myconodules-globular root structures that can host mycorrhizal fungi. The myconodule association is different from the wide-spread arbuscular mycorrhization. This range of symbiotic associations provides different degrees of compartmentalisation, from the cellular to organ scale, which allows the plant host to regulate the entry and extent of symbiotic interactions. In this review, we discuss the degrees of symbiont compartmentalisation by the plant host as a developmental strategy and speculate how spatial confinement mitigates risks associated with root symbiosis.
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Affiliation(s)
| | - Colleen Drapek
- Sainsbury Laboratory Cambridge University (SLCU), Bateman Street, Cambridge, UK
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Ghosh S, Reuman D, Bever JD. Preferential allocation of benefits and resource competition among recipients allows coexistence of symbionts within hosts. Am Nat 2021; 199:468-479. [DOI: 10.1086/718643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Pellitier PT, Zak DR. Ectomycorrhizal fungal decay traits along a soil nitrogen gradient. THE NEW PHYTOLOGIST 2021; 232:2152-2164. [PMID: 34533216 DOI: 10.1111/nph.17734] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 08/16/2021] [Indexed: 06/13/2023]
Abstract
The extent to which ectomycorrhizal (ECM) fungi decay soil organic matter (SOM) has implications for accurately predicting forest ecosystem response to climate change. Investigating the distribution of gene traits associated with SOM decay among ectomycorrhizal fungal communities could improve understanding of SOM dynamics and plant nutrition. We hypothesized that soil inorganic nitrogen (N) availability structures the distribution of ECM fungal genes associated with SOM decay and, specifically, that ECM fungal communities occurring in inorganic N-poor soils have greater SOM decay potential. To test this hypothesis, we paired amplicon and shotgun metagenomic sequencing of 60 ECM fungal communities associating with Quercus rubra along a natural soil inorganic N gradient. Ectomycorrhizal fungal communities occurring in low inorganic N soils were enriched in gene families involved in the decay of lignin, cellulose, and chitin. Ectomycorrhizal fungal community composition was the strongest driver of shifts in metagenomic estimates of fungal decay potential. Our study simultaneously illuminates the identity of key ECM fungal taxa and gene families potentially involved in the decay of SOM, and we link rhizomorphic and medium-distance hyphal morphologies with enhanced SOM decay potential. Coupled shifts in ECM fungal community composition and community-level decay gene frequencies are consistent with outcomes of trait-mediated community assembly processes.
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Affiliation(s)
- Peter T Pellitier
- School for Environment and Sustainability, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Donald R Zak
- School for Environment and Sustainability, University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA
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Steidinger BS, Peay KG. Optimal Allocation Ratios: A Square Root Relationship between the Ratios of Symbiotic Costs and Benefits. Am Nat 2021; 198:460-472. [PMID: 34559611 DOI: 10.1086/716182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractAll organisms struggle to make sense of environmental stimuli in order to maximize their fitness. For animals, the responses of single cells and superorganisms to stimuli are generally proportional to stimulus ratios, a phenomenon described by Weber's law. However, Weber's law has not yet been used to predict how plants respond to stimuli generated from their symbiotic partners. Here we develop a model for quantitatively predicting the ratios of carbon (C) allocation to symbionts that provide nutrients to their plant host. Consistent with Weber's law, our model demonstrates that the optimal ratio of resources allocated to a less beneficial relative to a more beneficial symbiont scale to the ratio of the growth benefits of the two strains. As C allocation to symbionts increases, the ratio of C allocation to two strains approaches the square root of the ratio of symbiotic growth benefits (e.g., a worse symbiont providing one-fourth the benefits gets 1/4=1/2 the C of a better symbiont). We document a compelling correspondence between our square root model prediction and a meta-analysis of experimental literature on C allocation. This type of preferential allocation can promote coexistence between more beneficial and less beneficial symbionts, offering a potential mechanism behind the high diversity of microbial symbionts observed in nature.
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Pellitier PT, Ibáñez I, Zak DR, Argiroff WA, Acharya K. Ectomycorrhizal access to organic nitrogen mediates CO 2 fertilization response in a dominant temperate tree. Nat Commun 2021; 12:5403. [PMID: 34518539 PMCID: PMC8438073 DOI: 10.1038/s41467-021-25652-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 08/19/2021] [Indexed: 01/04/2023] Open
Abstract
Plant–mycorrhizal interactions mediate plant nitrogen (N) limitation and can inform model projections of the duration and strength of the effect of increasing CO2 on plant growth. We present dendrochronological evidence of a positive, but context-dependent fertilization response of Quercus rubra L. to increasing ambient CO2 (iCO2) along a natural soil nutrient gradient in a mature temperate forest. We investigated this heterogeneous response by linking metagenomic measurements of ectomycorrhizal (ECM) fungal N-foraging traits and dendrochronological models of plant uptake of inorganic N and N bound in soil organic matter (N-SOM). N-SOM putatively enhanced tree growth under conditions of low inorganic N availability, soil conditions where ECM fungal communities possessed greater genomic potential to decay SOM and obtain N-SOM. These trees were fertilized by 38 years of iCO2. In contrast, trees occupying inorganic N rich soils hosted ECM fungal communities with reduced SOM decay capacity and exhibited neutral growth responses to iCO2. This study elucidates how the distribution of N-foraging traits among ECM fungal communities govern tree access to N-SOM and subsequent growth responses to iCO2. Root-mycorrhizal interactions could help explain the heterogeneity of plant responses to CO2 fertilisation and nutrient availability. Here the authors combine tree-ring and metagenomic data to reveal that tree growth responses to increasing CO2 along a soil nutrient gradient depend on the nitrogen foraging traits of ectomycorrhizal fungi.
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Affiliation(s)
- Peter T Pellitier
- School for Environment and Sustainability, University of Michigan, Ann Arbor, MI, USA. .,Department of Biology, Stanford University, Stanford, CA, USA.
| | - Inés Ibáñez
- School for Environment and Sustainability, University of Michigan, Ann Arbor, MI, USA
| | - Donald R Zak
- School for Environment and Sustainability, University of Michigan, Ann Arbor, MI, USA.
| | - William A Argiroff
- School for Environment and Sustainability, University of Michigan, Ann Arbor, MI, USA
| | - Kirk Acharya
- School for Environment and Sustainability, University of Michigan, Ann Arbor, MI, USA
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Pellitier PT, Zak DR, Argiroff WA, Upchurch RA. Coupled Shifts in Ectomycorrhizal Communities and Plant Uptake of Organic Nitrogen Along a Soil Gradient: An Isotopic Perspective. Ecosystems 2021. [DOI: 10.1007/s10021-021-00628-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Martignoni MM, Hart MM, Garnier J, Tyson RC. Parasitism within mutualist guilds explains the maintenance of diversity in multi-species mutualisms. THEOR ECOL-NETH 2020. [DOI: 10.1007/s12080-020-00472-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Younginger BS, Friesen ML. Connecting signals and benefits through partner choice in plant-microbe interactions. FEMS Microbiol Lett 2020; 366:5626345. [PMID: 31730203 DOI: 10.1093/femsle/fnz217] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 10/17/2019] [Indexed: 12/20/2022] Open
Abstract
Stabilizing mechanisms in plant-microbe symbioses are critical to maintaining beneficial functions, with two main classes: host sanctions and partner choice. Sanctions are currently presumed to be more effective and widespread, based on the idea that microbes rapidly evolve cheating while retaining signals matching cooperative strains. However, hosts that effectively discriminate among a pool of compatible symbionts would gain a significant fitness advantage. Using the well-characterized legume-rhizobium symbiosis as a model, we evaluate the evidence for partner choice in the context of the growing field of genomics. Empirical studies that rely upon bacteria varying only in nitrogen-fixation ability ignore host-symbiont signaling and frequently conclude that partner choice is not a robust stabilizing mechanism. Here, we argue that partner choice is an overlooked mechanism of mutualism stability and emphasize that plants need not use the microbial services provided a priori to discriminate among suitable partners. Additionally, we present a model that shows that partner choice signaling increases symbiont and host fitness in the absence of sanctions. Finally, we call for a renewed focus on elucidating the signaling mechanisms that are critical to partner choice while further aiming to understand their evolutionary dynamics in nature.
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Affiliation(s)
- Brett S Younginger
- Department of Plant Pathology, Washington State University, PO Box 646430, 345 Johnson Hall, Pullman, WA 99164, USA
| | - Maren L Friesen
- Department of Plant Pathology, Washington State University, PO Box 646430, 345 Johnson Hall, Pullman, WA 99164, USA.,Department of Crop and Soil Sciences, Washington State University, PO Box 646420, 115 Johnson Hall, Pullman, WA 99164, USA
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Heath KD, Podowski JC, Heniff S, Klinger CR, Burke PV, Weese DJ, Yang WH, Lau JA. Light availability and rhizobium variation interactively mediate the outcomes of legume-rhizobium symbiosis. AMERICAN JOURNAL OF BOTANY 2020; 107:229-238. [PMID: 32072629 DOI: 10.1002/ajb2.1435] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 12/08/2019] [Indexed: 05/22/2023]
Abstract
PREMISE Nutrients, light, water, and temperature are key factors limiting the growth of individual plants in nature. Mutualistic interactions between plants and microbes often mediate resource limitation for both partners. In the mutualism between legumes and rhizobia, plants provide rhizobia with carbon in exchange for fixed nitrogen. Because partner quality in mutualisms is genotype-dependent, within-species genetic variation is expected to alter the responses of mutualists to changes in the resource environment. Here we ask whether partner quality variation in rhizobia mediates the response of host plants to changing light availability, and conversely, whether light alters the expression of partner quality variation. METHODS We inoculated clover hosts with 11 strains of Rhizobium leguminosarum that differed in partner quality, grew plants under either ambient or low light conditions in the greenhouse, and measured plant growth, nodule traits, and foliar nutrient composition. RESULTS Light availability and rhizobium inoculum interactively determined plant growth, and variation in rhizobium partner quality was more apparent in ambient light. CONCLUSIONS Our results suggest that variation in the costs and benefits of rhizobium symbionts mediate host responses to light availability and that rhizobium strain variation might more important in higher-light environments. Our work adds to a growing appreciation for the role of microbial intraspecific and interspecific diversity in mediating extended phenotypes in their hosts and suggests an important role for light availability in the ecology and evolution of legume-rhizobium symbiosis.
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Affiliation(s)
- Katy D Heath
- Department of Plant Biology, University of Illinois at Urbana-Champaign, 505 S. Goodwin Ave., Urbana, IL, 61801, USA
| | - Justin C Podowski
- Department of Plant Biology, University of Illinois at Urbana-Champaign, 505 S. Goodwin Ave., Urbana, IL, 61801, USA
| | - Stephanie Heniff
- Department of Plant Biology, University of Illinois at Urbana-Champaign, 505 S. Goodwin Ave., Urbana, IL, 61801, USA
| | - Christie R Klinger
- Department of Plant Biology, University of Illinois at Urbana-Champaign, 505 S. Goodwin Ave., Urbana, IL, 61801, USA
| | - Patricia V Burke
- Department of Plant Biology, University of Illinois at Urbana-Champaign, 505 S. Goodwin Ave., Urbana, IL, 61801, USA
| | - Dylan J Weese
- Department of Biology, St. Ambrose University, Davenport, IA, 52803, USA
| | - Wendy H Yang
- Department of Plant Biology, University of Illinois at Urbana-Champaign, 505 S. Goodwin Ave., Urbana, IL, 61801, USA
| | - Jennifer A Lau
- W. K. Kellogg Biological Station and Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA
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11
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Chomicki G, Weber M, Antonelli A, Bascompte J, Kiers ET. The Impact of Mutualisms on Species Richness. Trends Ecol Evol 2019; 34:698-711. [DOI: 10.1016/j.tree.2019.03.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 03/11/2019] [Accepted: 03/18/2019] [Indexed: 11/28/2022]
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Bogar L, Peay K, Kornfeld A, Huggins J, Hortal S, Anderson I, Kennedy P. Plant-mediated partner discrimination in ectomycorrhizal mutualisms. MYCORRHIZA 2019; 29:97-111. [PMID: 30617861 DOI: 10.1007/s00572-018-00879-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 12/26/2018] [Indexed: 05/22/2023]
Abstract
Although ectomycorrhizal fungi have well-recognized effects on ecological processes ranging from plant community dynamics to carbon cycling rates, it is unclear if plants are able to actively influence the structure of these fungal communities. To address this knowledge gap, we performed two complementary experiments to determine (1) whether ectomycorrhizal plants can discriminate among potential fungal partners, and (2) to what extent the plants might reward better mutualists. In experiment 1, split-root Larix occidentalis seedlings were inoculated with spores from three Suillus species (S. clintonianus, S. grisellus, and S. spectabilis). In experiment 2, we manipulated the symbiotic quality of Suillus brevipes isolates on split-root Pinus muricata seedlings by changing the nitrogen resources available, and used carbon-13 labeling to track host investment in fungi. In experiment 1, we found that hosts can discriminate in multi-species settings. The split-root seedlings inhibited colonization by S. spectabilis whenever another fungus was available, despite similar benefits from all three fungi. In experiment 2, we found that roots and fungi with greater nitrogen supplies received more plant carbon. Our results suggest that plants may be able to regulate this symbiosis at a relatively fine scale, and that this regulation can be integrated across spatially separated portions of a root system.
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Affiliation(s)
- Laura Bogar
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA, 94305, USA.
| | - Kabir Peay
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA, 94305, USA
| | - Ari Kornfeld
- Department of Global Ecology, Carnegie Institution for Science, Stanford, CA, 94305, USA
| | - Julia Huggins
- Department of Plant & Microbial Biology, University of Minnesota, Saint Paul, MN, 55108, USA
| | - Sara Hortal
- Hawkesbury Institute for the Environment, Western Sydney University, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Ian Anderson
- Hawkesbury Institute for the Environment, Western Sydney University, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Peter Kennedy
- Department of Plant & Microbial Biology, University of Minnesota, Saint Paul, MN, 55108, USA
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