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Laurich JR, Lash E, O'Brien AM, Pogoutse O, Frederickson ME. Community interactions among microbes give rise to host-microbiome mutualisms in an aquatic plant. mBio 2024; 15:e0097224. [PMID: 38904411 DOI: 10.1128/mbio.00972-24] [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: 04/19/2024] [Accepted: 05/14/2024] [Indexed: 06/22/2024] Open
Abstract
Microbiomes often benefit plants, conferring resistance to pathogens, improving stress tolerance, or promoting plant growth. As potential plant mutualists, however, microbiomes are not a single organism but a community of species with complex interactions among microbial taxa and between microbes and their shared host. The nature of ecological interactions among microbes in the microbiome can have important consequences for the net effects of microbiomes on hosts. Here, we compared the effects of individual microbial strains and 10-strain synthetic communities on microbial productivity and host growth using the common duckweed Lemna minor and a synthetic, simplified version of its native microbiome. Except for Pseudomonas protegens, which was a mutualist when tested alone, all of the single strains we tested were commensals on hosts, benefiting from plant presence but not increasing host growth relative to uninoculated controls. However, 10-strain synthetic microbial communities increased both microbial productivity and duckweed growth more than the average single-strain inoculation and uninoculated controls, meaning that host-microbiome mutualisms can emerge from community interactions among microbes on hosts. The effects of community inoculation were sub-additive, suggesting at least some competition among microbes in the duckweed microbiome. We also investigated the relationship between L. minor fitness and that of its microbes, providing some of the first empirical estimates of broad fitness alignment between plants and members of their microbiomes; hosts grew faster with more productive microbes or microbiomes. IMPORTANCE There is currently substantial interest in engineering synthetic microbiomes for health or agricultural applications. One key question is how multi-strain microbial communities differ from single microbial strains in their productivity and effects on hosts. We tested 20 single bacterial strains and 2 distinct 10-strain synthetic communities on plant hosts and found that 10-strain communities led to faster host growth and greater microbial productivity than the average, but not the best, single strain. Furthermore, the microbial strains or communities that achieved the greatest cell densities were also the most beneficial to their hosts, showing that both specific single strains and multi-strain synthetic communities can engage in high-quality mutualisms with their hosts. Our results suggest that ~5% of single strains, as well as multi-strain synthetic communities comprised largely of commensal microbes, can benefit hosts and result in effective host-microbe mutualisms.
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Affiliation(s)
- Jason R Laurich
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Emma Lash
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Anna M O'Brien
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire, USA
| | - Oxana Pogoutse
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Megan E Frederickson
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
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2
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Semenova MG, Petina AN, Fedorova EE. Autophagy and Symbiosis: Membranes, ER, and Speculations. Int J Mol Sci 2024; 25:2918. [PMID: 38474164 DOI: 10.3390/ijms25052918] [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: 12/27/2023] [Revised: 02/19/2024] [Accepted: 02/26/2024] [Indexed: 03/14/2024] Open
Abstract
The interaction of plants and soil bacteria rhizobia leads to the formation of root nodule symbiosis. The intracellular form of rhizobia, the symbiosomes, are able to perform the nitrogen fixation by converting atmospheric dinitrogen into ammonia, which is available for plants. The symbiosis involves the resource sharing between two partners, but this exchange does not include equivalence, which can lead to resource scarcity and stress responses of one of the partners. In this review, we analyze the possible involvement of the autophagy pathway in the process of the maintenance of the nitrogen-fixing bacteria intracellular colony and the changes in the endomembrane system of the host cell. According to in silico expression analysis, ATG genes of all groups were expressed in the root nodule, and the expression was developmental zone dependent. The analysis of expression of genes involved in the response to carbon or nitrogen deficiency has shown a suboptimal access to sugars and nitrogen in the nodule tissue. The upregulation of several ER stress genes was also detected. Hence, the root nodule cells are under heavy bacterial infection, carbon deprivation, and insufficient nitrogen supply, making nodule cells prone to autophagy. We speculate that the membrane formation around the intracellular rhizobia may be quite similar to the phagophore formation, and the induction of autophagy and ER stress are essential to the success of this process.
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Affiliation(s)
- Maria G Semenova
- Timiryazev Institute of Plant Physiology, Russian Academy of Science, 127276 Moscow, Russia
| | - Alekandra N Petina
- Timiryazev Institute of Plant Physiology, Russian Academy of Science, 127276 Moscow, Russia
| | - Elena E Fedorova
- Timiryazev Institute of Plant Physiology, Russian Academy of Science, 127276 Moscow, Russia
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3
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O'Brien AM, Laurich JR, Frederickson ME. Evolutionary consequences of microbiomes for hosts: impacts on host fitness, traits, and heritability. Evolution 2024; 78:237-252. [PMID: 37828761 DOI: 10.1093/evolut/qpad183] [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: 02/22/2022] [Revised: 08/30/2023] [Accepted: 10/03/2023] [Indexed: 10/14/2023]
Abstract
An organism's phenotypes and fitness often depend on the interactive effects of its genome (Ghost), microbiome (Gmicrobe), and environment (E). These G × G, G × E, and G × G × E effects fundamentally shape host-microbiome (co)evolution and may be widespread, but are rarely compared within a single experiment. We collected and cultured Lemnaminor (duckweed) and its associated microbiome from 10 sites across an urban-to-rural ecotone. We factorially manipulated host genotype and microbiome in two environments (low and high zinc, an urban aquatic stressor) in an experiment with 200 treatments: 10 host genotypes × 10 microbiomes × 2 environments. Host genotype explained the most variation in L.minor fitness and traits, while microbiome effects often depended on host genotype (G × G). Microbiome composition predicted G × G effects: when compared in more similar microbiomes, duckweed genotypes had more similar effects on traits. Further, host fitness increased and microbes grew faster when applied microbiomes more closely matched the host's field microbiome, suggesting some local adaptation between hosts and microbiota. Finally, selection on and heritability of host traits shifted across microbiomes and zinc exposure. Thus, we found that microbiomes impact host fitness, trait expression, and heritability, with implications for host-microbiome evolution and microbiome breeding.
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Affiliation(s)
- Anna M O'Brien
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, United States
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | - Jason R Laurich
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | - Megan E Frederickson
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
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4
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Granada Agudelo M, Ruiz B, Capela D, Remigi P. The role of microbial interactions on rhizobial fitness. FRONTIERS IN PLANT SCIENCE 2023; 14:1277262. [PMID: 37877089 PMCID: PMC10591227 DOI: 10.3389/fpls.2023.1277262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 09/22/2023] [Indexed: 10/26/2023]
Abstract
Rhizobia are soil bacteria that can establish a nitrogen-fixing symbiosis with legume plants. As horizontally transmitted symbionts, the life cycle of rhizobia includes a free-living phase in the soil and a plant-associated symbiotic phase. Throughout this life cycle, rhizobia are exposed to a myriad of other microorganisms that interact with them, modulating their fitness and symbiotic performance. In this review, we describe the diversity of interactions between rhizobia and other microorganisms that can occur in the rhizosphere, during the initiation of nodulation, and within nodules. Some of these rhizobia-microbe interactions are indirect, and occur when the presence of some microbes modifies plant physiology in a way that feeds back on rhizobial fitness. We further describe how these interactions can impose significant selective pressures on rhizobia and modify their evolutionary trajectories. More extensive investigations on the eco-evolutionary dynamics of rhizobia in complex biotic environments will likely reveal fascinating new aspects of this well-studied symbiotic interaction and provide critical knowledge for future agronomical applications.
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Affiliation(s)
- Margarita Granada Agudelo
- Laboratoire des Interactions Plantes Microbes Environnement (LIPME), Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Bryan Ruiz
- Laboratoire des Interactions Plantes Microbes Environnement (LIPME), Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Delphine Capela
- Laboratoire des Interactions Plantes Microbes Environnement (LIPME), Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Philippe Remigi
- Laboratoire des Interactions Plantes Microbes Environnement (LIPME), Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
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5
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Rahman A, Manci M, Nadon C, Perez IA, Farsamin WF, Lampe MT, Le TH, Torres Martínez L, Weisberg AJ, Chang JH, Sachs JL. Competitive interference among rhizobia reduces benefits to hosts. Curr Biol 2023; 33:2988-3001.e4. [PMID: 37490853 DOI: 10.1016/j.cub.2023.06.081] [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] [Received: 01/23/2023] [Revised: 03/31/2023] [Accepted: 06/29/2023] [Indexed: 07/27/2023]
Abstract
The capacity of beneficial microbes to compete for host infection-and the ability of hosts to discriminate among them-introduces evolutionary conflict that is predicted to destabilize mutualism. We investigated fitness outcomes in associations between legumes and their symbiotic rhizobia to characterize fitness impacts of microbial competition. Diverse Bradyrhizobium strains varying in their capacity to fix nitrogen symbiotically with a common host plant, Acmispon strigosus, were tested in full-factorial coinoculation experiments involving 28 pairwise strain combinations. We analyzed the effects of interstrain competition and host discrimination on symbiotic-interaction outcomes by relativizing fitness proxies to clonally infected and uninfected controls. More than one thousand root nodules of coinoculated plants were genotyped to quantify strain occupancy, and the Bradyrhizobium strain genome sequences were analyzed to uncover the genetic bases of interstrain competition outcomes. Strikingly, interstrain competition favored a fast-growing, minimally beneficial rhizobia strain. Host benefits were significantly diminished in coinoculation treatments relative to expectations from clonally inoculated controls, consistent with competitive interference among rhizobia that reduced both nodulation and plant growth. Competition traits appear polygenic, linked with inter-strain allelopathic interactions in the rhizosphere. This study confirms that competition among strains can destabilize mutualism by favoring microbes that are superior in colonizing host tissues but provide minimal benefits to host plants. Moreover, our findings help resolve the paradox that despite efficient host control post infection, legumes nonetheless encounter rhizobia that vary in their nitrogen fixation.
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Affiliation(s)
- Arafat Rahman
- Institute of Integrative Genome Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Max Manci
- Department of Microbiology & Plant Pathology, University of California, Riverside, Riverside, CA 92521, USA
| | - Cassandra Nadon
- Department of Evolution Ecology & Organismal Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Ivan A Perez
- Department of Evolution Ecology & Organismal Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Warisha F Farsamin
- Department of Evolution Ecology & Organismal Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Matthew T Lampe
- Department of Evolution Ecology & Organismal Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Tram H Le
- Department of Evolution Ecology & Organismal Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Lorena Torres Martínez
- Department of Evolution Ecology & Organismal Biology, University of California, Riverside, Riverside, CA 92521, USA; Department of Biology, St. Mary's College of Maryland, St. Mary's City, MD 20686, USA
| | - Alexandra J Weisberg
- Department of Botany & Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Jeff H Chang
- Department of Botany & Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Joel L Sachs
- Institute of Integrative Genome Biology, University of California, Riverside, Riverside, CA 92521, USA; Department of Microbiology & Plant Pathology, University of California, Riverside, Riverside, CA 92521, USA; Department of Evolution Ecology & Organismal Biology, University of California, Riverside, Riverside, CA 92521, USA.
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6
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Parshuram ZA, Harrison TL, Simonsen AK, Stinchcombe JR, Frederickson ME. Nonsymbiotic legumes are more invasive, but only if polyploid. THE NEW PHYTOLOGIST 2023; 237:758-765. [PMID: 36305214 DOI: 10.1111/nph.18579] [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: 08/24/2022] [Accepted: 10/15/2022] [Indexed: 06/16/2023]
Abstract
Both mutualism and polyploidy are thought to influence invasion success in plants, but few studies have tested their joint effects. Mutualism can limit range expansion when plants cannot find a compatible partner in a novel habitat, or facilitate range expansion when mutualism increases a plant's niche breadth. Polyploids are also expected to have greater niche breadth because of greater self-compatibility and phenotypic plasticity, increasing invasion success. For 847 legume species, we compiled data from published sources to estimate ploidy, symbiotic status with rhizobia, specificity on rhizobia, and the number of introduced ranges. We found that diploid species have had limited spread around the globe regardless of whether they are symbiotic or how many rhizobia partners they can host. Polyploids, by contrast, have been successfully introduced to many new ranges, but interactions with rhizobia constrain their range expansion. In a hidden state model of trait evolution, we also found evidence of a high rate of re-diploidization in symbiotic legume lineages, suggesting that symbiosis and ploidy may interact at macroevolutionary scales. Overall, our results suggest that symbiosis with rhizobia limits range expansion when legumes are polyploid but not diploid.
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Affiliation(s)
- Zoe A Parshuram
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Tia L Harrison
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Anna K Simonsen
- Department of Biological Sciences, Florida International University, Miami, FL, 33199, USA
| | - John R Stinchcombe
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Megan E Frederickson
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
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7
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Cassidy ST, Markalanda S, McFadden CJ, Wood CW. Herbivory modifies plant symbiont number and impact on host plant performance in the field. Evolution 2022; 76:2945-2958. [PMID: 36221227 DOI: 10.1111/evo.14641] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 07/14/2022] [Accepted: 08/15/2022] [Indexed: 01/22/2023]
Abstract
Species interactions are a unifying theme in ecology and evolution. Both fields are currently moving beyond their historical focus on isolated pairwise relationships to understand how ecological communities affect focal interactions. Additional species can modify both the number of interactions and the fitness consequences of each interaction (i.e., selection). Although only selection affects the evolution of the focal interaction, the two are often conflated, limiting our understanding of the evolution of multispecies interactions. We manipulated aboveground herbivory on the legume Medicago lupulina in the field and quantified its effect on number of symbionts and the per-symbiont impact on plant performance in two belowground symbioses: mutualistic rhizobia bacteria (Ensifer meliloti) and parasitic root-knot nematodes (Meloidogyne hapla). We found that herbivores modified the number of rhizobia nodules, as well as the benefit per nodule. However, each effect was specific to a distinct herbivory regime: natural herbivory affected nodule number, whereas leafhoppers (Cicadellidae) weakened the per nodule benefit. We did not detect any effect of herbivory on nematode gall number or the cost of infection. Our data demonstrate that distinguishing between symbiont number from the fitness consequences of symbiosis is crucial to accurately infer how pairwise interactions will evolve in a community.
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Affiliation(s)
- Steven T Cassidy
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260, USA.,Department of Biology, University of Florida, Gainesville, Florida, 32611, USA
| | - Shaniya Markalanda
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260, USA
| | - Connor J McFadden
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260, USA
| | - Corlett W Wood
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260, USA.,Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, USA
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8
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Batstone RT, Burghardt LT, Heath KD. Phenotypic and genomic signatures of interspecies cooperation and conflict in naturally occurring isolates of a model plant symbiont. Proc Biol Sci 2022; 289:20220477. [PMID: 35858063 PMCID: PMC9277234 DOI: 10.1098/rspb.2022.0477] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Given the need to predict the outcomes of (co)evolution in host-associated microbiomes, whether microbial and host fitnesses tend to trade-off, generating conflict, remains a pressing question. Examining the relationships between host and microbe fitness proxies at both the phenotypic and genomic levels can illuminate the mechanisms underlying interspecies cooperation and conflict. We examined naturally occurring genetic variation in 191 strains of the model microbial symbiont Sinorhizobium meliloti, paired with each of two host Medicago truncatula genotypes in single- or multi-strain experiments to determine how multiple proxies of microbial and host fitness were related to one another and test key predictions about mutualism evolution at the genomic scale, while also addressing the challenge of measuring microbial fitness. We found little evidence for interspecies fitness conflict; loci tended to have concordant effects on both microbe and host fitnesses, even in environments with multiple co-occurring strains. Our results emphasize the importance of quantifying microbial relative fitness for understanding microbiome evolution and thus harnessing microbiomes to improve host fitness. Additionally, we find that mutualistic coevolution between hosts and microbes acts to maintain, rather than erode, genetic diversity, potentially explaining why variation in mutualism traits persists in nature.
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Affiliation(s)
- Rebecca T. Batstone
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 West Gregory Drive, Urbana, IL 61801, USA
| | - Liana T. Burghardt
- Department of Plant Science, The Pennsylvania State University, 103 Tyson Building, University Park, PA, 16802 USA
| | - Katy D. Heath
- Department of Plant Biology, University of Illinois at Urbana-Champaign, 286 Morrill Hall, 505 South Goodwin Avenue, Urbana, IL 61801, USA
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9
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Wendlandt CE, Roberts M, Nguyen KT, Graham ML, Lopez Z, Helliwell EE, Friesen ML, Griffitts JS, Price P, Porter SS. Negotiating mutualism: A locus for exploitation by rhizobia has a broad effect size distribution and context-dependent effects on legume hosts. J Evol Biol 2022; 35:844-854. [PMID: 35506571 PMCID: PMC9325427 DOI: 10.1111/jeb.14011] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 03/07/2022] [Accepted: 04/02/2022] [Indexed: 01/02/2023]
Abstract
In mutualisms, variation at genes determining partner fitness provides the raw material upon which coevolutionary selection acts, setting the dynamics and pace of coevolution. However, we know little about variation in the effects of genes that underlie symbiotic fitness in natural mutualist populations. In some species of legumes that form root nodule symbioses with nitrogen‐fixing rhizobial bacteria, hosts secrete nodule‐specific cysteine‐rich (NCR) peptides that cause rhizobia to differentiate in the nodule environment. However, rhizobia can cleave NCR peptides through the expression of genes like the plasmid‐borne Host range restriction peptidase (hrrP), whose product degrades specific NCR peptides. Although hrrP activity can confer host exploitation by depressing host fitness and enhancing symbiont fitness, the effects of hrrP on symbiosis phenotypes depend strongly on the genotypes of the interacting partners. However, the effects of hrrP have yet to be characterised in a natural population context, so its contribution to variation in wild mutualist populations is unknown. To understand the distribution of effects of hrrP in wild rhizobia, we measured mutualism phenotypes conferred by hrrP in 12 wild Ensifer medicae strains. To evaluate context dependency of hrrP effects, we compared hrrP effects across two Medicago polymorpha host genotypes and across two experimental years for five E. medicae strains. We show for the first time in a natural population context that hrrP has a wide distribution of effect sizes for many mutualism traits, ranging from strongly positive to strongly negative. Furthermore, we show that hrrP effect size varies across host genotypes and experiment years, suggesting that researchers should be cautious about extrapolating the role of genes in natural populations from controlled laboratory studies of single genetic variants.
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Affiliation(s)
- Camille E Wendlandt
- School of Biological Sciences, Washington State University, Vancouver, Washington, USA
| | - Miles Roberts
- School of Biological Sciences, Washington State University, Vancouver, Washington, USA
| | - Kyle T Nguyen
- School of Biological Sciences, Washington State University, Vancouver, Washington, USA
| | - Marion L Graham
- Biology Department, Eastern Michigan University, Ypsilanti, Michigan, USA
| | - Zoie Lopez
- School of Biological Sciences, Washington State University, Vancouver, Washington, USA
| | - Emily E Helliwell
- School of Biological Sciences, Washington State University, Vancouver, Washington, USA
| | - Maren L Friesen
- Department of Plant Pathology, Washington State University, Pullman, Washington, USA.,Department of Crop & Soil Sciences, Washington State University, Pullman, Washington, USA
| | - Joel S Griffitts
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, Utah, USA
| | - Paul Price
- Biology Department, Eastern Michigan University, Ypsilanti, Michigan, USA
| | - Stephanie S Porter
- School of Biological Sciences, Washington State University, Vancouver, Washington, USA
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10
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Denison RF, Muller KE. An evolutionary perspective on increasing net benefits to crops from symbiotic microbes. Evol Appl 2022; 15:1490-1504. [PMID: 36330301 PMCID: PMC9624085 DOI: 10.1111/eva.13384] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 04/05/2022] [Accepted: 04/06/2022] [Indexed: 11/30/2022] Open
Abstract
Plant‐imposed, fitness‐reducing sanctions against less‐beneficial symbionts have been documented for rhizobia, mycorrhizal fungi, and fig wasps. Although most of our examples are for rhizobia, we argue that the evolutionary persistence of mutualism in any symbiosis would require such sanctions, if there are multiple symbiont genotypes per host plant. We therefore discuss methods that could be used to develop and assess crops with stricter sanctions. These include methods to screen strains for greater mutualism as resources to identify crop genotypes that impose stronger selection for mutualism. Single‐strain experiments that measure costs as well as benefits have shown that diversion of resources by rhizobia can reduce nitrogen‐fixation efficiency (N per C) and that some legumes can increase this efficiency by manipulating their symbionts. Plants in the field always host multiple strains with possible synergistic interactions, so benefits from different strains might best be compared by regressing plant growth or yield on each strain's abundance in a mixture. However, results from this approach have not yet been published. To measure legacy effects of stronger sanctions on future crops, single‐genotype test crops could be planted in a field that recently had replicated plots with different genotypes of the sanction‐imposing crop. Enhancing agricultural benefits from symbiosis may require accepting tradeoffs that constrained past natural selection, including tradeoffs between current and future benefits.
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Affiliation(s)
- R. Ford Denison
- Ecology Evolution and Behavior University of Minnesota Twin Cities Saint Paul USA
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11
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Cangioli L, Vaccaro F, Fini M, Mengoni A, Fagorzi C. Scent of a Symbiont: The Personalized Genetic Relationships of Rhizobium—Plant Interaction. Int J Mol Sci 2022; 23:ijms23063358. [PMID: 35328782 PMCID: PMC8954435 DOI: 10.3390/ijms23063358] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/17/2022] [Accepted: 03/18/2022] [Indexed: 01/24/2023] Open
Abstract
Many molecular signals are exchanged between rhizobia and host legume plants, some of which are crucial for symbiosis to take place, while others are modifiers of the interaction, which have great importance in the competition with the soil microbiota and in the genotype-specific perception of host plants. Here, we review recent findings on strain-specific and host genotype-specific interactions between rhizobia and legumes, discussing the molecular actors (genes, gene products and metabolites) which play a role in the establishment of symbiosis, and highlighting the need for research including the other components of the soil (micro)biota, which could be crucial in developing rational-based strategies for bioinoculants and synthetic communities’ assemblage.
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12
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Bellabarba A, Bacci G, Decorosi F, Aun E, Azzarello E, Remm M, Giovannetti L, Viti C, Mengoni A, Pini F. Competitiveness for Nodule Colonization in Sinorhizobium meliloti: Combined In Vitro-Tagged Strain Competition and Genome-Wide Association Analysis. mSystems 2021. [PMID: 34313466 DOI: 10.1101/2020.09.15.298034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023] Open
Abstract
Associations between leguminous plants and symbiotic nitrogen-fixing rhizobia are a classic example of mutualism between a eukaryotic host and a specific group of prokaryotic microbes. Although this symbiosis is in part species specific, different rhizobial strains may colonize the same nodule. Some rhizobial strains are commonly known as better competitors than others, but detailed analyses that aim to predict rhizobial competitive abilities based on genomes are still scarce. Here, we performed a bacterial genome-wide association (GWAS) analysis to define the genomic determinants related to the competitive capabilities in the model rhizobial species Sinorhizobium meliloti. For this, 13 tester strains were green fluorescent protein (GFP) tagged and assayed versus 3 red fluorescent protein (RFP)-tagged reference competitor strains (Rm1021, AK83, and BL225C) in a Medicago sativa nodule occupancy test. Competition data and strain genomic sequences were employed to build a model for GWAS based on k-mers. Among the k-mers with the highest scores, 51 k-mers mapped on the genomes of four strains showing the highest competition phenotypes (>60% single strain nodule occupancy; GR4, KH35c, KH46, and SM11) versus BL225C. These k-mers were mainly located on the symbiosis-related megaplasmid pSymA, specifically on genes coding for transporters, proteins involved in the biosynthesis of cofactors, and proteins related to metabolism (e.g., fatty acids). The same analysis was performed considering the sum of single and mixed nodules obtained in the competition assays versus BL225C, retrieving k-mers mapped on the genes previously found and on vir genes. Therefore, the competition abilities seem to be linked to multiple genetic determinants and comprise several cellular components. IMPORTANCE Decoding the competitive pattern that occurs in the rhizosphere is challenging in the study of bacterial social interaction strategies. To date, the single-gene approach has mainly been used to uncover the bases of nodulation, but there is still a knowledge gap regarding the main features that a priori characterize rhizobial strains able to outcompete indigenous rhizobia. Therefore, tracking down which traits make different rhizobial strains able to win the competition for plant infection over other indigenous rhizobia will improve the strain selection process and, consequently, plant yield in sustainable agricultural production systems. We proved that a k-mer-based GWAS approach can efficiently identify the competition determinants of a panel of strains previously analyzed for their plant tissue occupancy using double fluorescent labeling. The reported strategy will be useful for detailed studies on the genomic aspects of the evolution of bacterial symbiosis and for an extensive evaluation of rhizobial inoculants.
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Affiliation(s)
- Agnese Bellabarba
- Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
- Genexpress Laboratory, Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
| | - Giovanni Bacci
- Department of Biology, University of Florencegrid.8404.8, Sesto Fiorentino, Italy
| | - Francesca Decorosi
- Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
- Genexpress Laboratory, Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
| | - Erki Aun
- Department of Bioinformatics, Institute of Molecular and Cell Biology, University of Tartugrid.10939.32, Tartu, Estonia
| | - Elisa Azzarello
- Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
| | - Maido Remm
- Department of Bioinformatics, Institute of Molecular and Cell Biology, University of Tartugrid.10939.32, Tartu, Estonia
| | - Luciana Giovannetti
- Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
- Genexpress Laboratory, Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
| | - Carlo Viti
- Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
- Genexpress Laboratory, Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
| | - Alessio Mengoni
- Department of Biology, University of Florencegrid.8404.8, Sesto Fiorentino, Italy
| | - Francesco Pini
- Department of Biology, University of Bari Aldo Morogrid.7644.1, Bari, Italy
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13
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Mendoza-Suárez M, Andersen SU, Poole PS, Sánchez-Cañizares C. Competition, Nodule Occupancy, and Persistence of Inoculant Strains: Key Factors in the Rhizobium-Legume Symbioses. FRONTIERS IN PLANT SCIENCE 2021; 12:690567. [PMID: 34489993 PMCID: PMC8416774 DOI: 10.3389/fpls.2021.690567] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Accepted: 07/19/2021] [Indexed: 05/06/2023]
Abstract
Biological nitrogen fixation by Rhizobium-legume symbioses represents an environmentally friendly and inexpensive alternative to the use of chemical nitrogen fertilizers in legume crops. Rhizobial inoculants, applied frequently as biofertilizers, play an important role in sustainable agriculture. However, inoculants often fail to compete for nodule occupancy against native rhizobia with inferior nitrogen-fixing abilities, resulting in low yields. Strains with excellent performance under controlled conditions are typically selected as inoculants, but the rates of nodule occupancy compared to native strains are rarely investigated. Lack of persistence in the field after agricultural cycles, usually due to the transfer of symbiotic genes from the inoculant strain to naturalized populations, also limits the suitability of commercial inoculants. When rhizobial inoculants are based on native strains with a high nitrogen fixation ability, they often have superior performance in the field due to their genetic adaptations to the local environment. Therefore, knowledge from laboratory studies assessing competition and understanding how diverse strains of rhizobia behave, together with assays done under field conditions, may allow us to exploit the effectiveness of native populations selected as elite strains and to breed specific host cultivar-rhizobial strain combinations. Here, we review current knowledge at the molecular level on competition for nodulation and the advances in molecular tools for assessing competitiveness. We then describe ongoing approaches for inoculant development based on native strains and emphasize future perspectives and applications using a multidisciplinary approach to ensure optimal performance of both symbiotic partners.
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Affiliation(s)
| | - Stig U. Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Philip S. Poole
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
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14
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Competitiveness for Nodule Colonization in Sinorhizobium meliloti: Combined In Vitro-Tagged Strain Competition and Genome-Wide Association Analysis. mSystems 2021; 6:e0055021. [PMID: 34313466 PMCID: PMC8407117 DOI: 10.1128/msystems.00550-21] [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] [Indexed: 01/15/2023] Open
Abstract
Associations between leguminous plants and symbiotic nitrogen-fixing rhizobia are a classic example of mutualism between a eukaryotic host and a specific group of prokaryotic microbes. Although this symbiosis is in part species specific, different rhizobial strains may colonize the same nodule. Some rhizobial strains are commonly known as better competitors than others, but detailed analyses that aim to predict rhizobial competitive abilities based on genomes are still scarce. Here, we performed a bacterial genome-wide association (GWAS) analysis to define the genomic determinants related to the competitive capabilities in the model rhizobial species Sinorhizobium meliloti. For this, 13 tester strains were green fluorescent protein (GFP) tagged and assayed versus 3 red fluorescent protein (RFP)-tagged reference competitor strains (Rm1021, AK83, and BL225C) in a Medicago sativa nodule occupancy test. Competition data and strain genomic sequences were employed to build a model for GWAS based on k-mers. Among the k-mers with the highest scores, 51 k-mers mapped on the genomes of four strains showing the highest competition phenotypes (>60% single strain nodule occupancy; GR4, KH35c, KH46, and SM11) versus BL225C. These k-mers were mainly located on the symbiosis-related megaplasmid pSymA, specifically on genes coding for transporters, proteins involved in the biosynthesis of cofactors, and proteins related to metabolism (e.g., fatty acids). The same analysis was performed considering the sum of single and mixed nodules obtained in the competition assays versus BL225C, retrieving k-mers mapped on the genes previously found and on vir genes. Therefore, the competition abilities seem to be linked to multiple genetic determinants and comprise several cellular components. IMPORTANCE Decoding the competitive pattern that occurs in the rhizosphere is challenging in the study of bacterial social interaction strategies. To date, the single-gene approach has mainly been used to uncover the bases of nodulation, but there is still a knowledge gap regarding the main features that a priori characterize rhizobial strains able to outcompete indigenous rhizobia. Therefore, tracking down which traits make different rhizobial strains able to win the competition for plant infection over other indigenous rhizobia will improve the strain selection process and, consequently, plant yield in sustainable agricultural production systems. We proved that a k-mer-based GWAS approach can efficiently identify the competition determinants of a panel of strains previously analyzed for their plant tissue occupancy using double fluorescent labeling. The reported strategy will be useful for detailed studies on the genomic aspects of the evolution of bacterial symbiosis and for an extensive evaluation of rhizobial inoculants.
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15
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The direct and interactive effects of elevated CO2 and additional nitrate on relative costs and benefits of legume-rhizobia symbiosis. Symbiosis 2021. [DOI: 10.1007/s13199-021-00784-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
AbstractRising concentrations of carbon dioxide (CO2) is likely to have important effects on growth and development of plants and on their relationship with symbiotic microbes. A rise in CO2 could increase demand by plant hosts for nutrient resources, which may increase host investments in beneficial symbionts. In the legume-rhizobia mutualism, while elevated CO2 is often associated with increased nodule growth and investment in N2-fixing rhizobia, it is yet unclear if this response depends on the mutualistic quality of the rhizobia. To test if host carbon allocation towards more-beneficial nodules are similar to less-beneficial (but still effective) nodules when plant N demand changes, we manipulated plant C and N status with elevated CO2 and additional nitrate. We used two isogenic Rhizobium etli strains that differ in their ability to synthesize an energy reserve compound, poly-beta-hydroxybutyrate (PHB), as well as their efficiencies for nitrogen fixation and nodulation rates, resulting in two Phaseolus vulgaris host groups with either large number of small nodules or small number of large nodules. The addition of nitrate negatively affected carbon allocation towards nodules, and elevated CO2 reversed this effect, as expected. However, this alleviation of nodule inhibition was greater on plants that started with greater numbers of smaller nodules. If smaller nodules indicate less-efficient or low-fixing rhizobia, this study suggests that increased demand for nitrogen in the face of elevated CO2 has the potential to disproportionately favor less-beneficial strains and increase variation of nitrogen fixation quality among rhizobia.
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16
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Six DL, Klepzig KD. Context Dependency in Bark Beetle-Fungus Mutualisms Revisited: Assessing Potential Shifts in Interaction Outcomes Against Varied Genetic, Ecological, and Evolutionary Backgrounds. Front Microbiol 2021; 12:682187. [PMID: 34054789 PMCID: PMC8149605 DOI: 10.3389/fmicb.2021.682187] [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: 03/17/2021] [Accepted: 04/19/2021] [Indexed: 11/13/2022] Open
Abstract
Context dependency occurs when biological interactions shift in sign or magnitude depending upon genetic, abiotic, and biotic context. Most models of mutualism address systems where interaction outcomes slide along a mutualism-antagonism continuum as environmental conditions vary altering cost-benefit relationships. However, these models do not apply to the many mutualisms that involve by-product benefits and others that do not have antagonistic alternate states. The ubiquity of such mutualisms indicates a need for different approaches and models to understand how environmental variability influences their strength, stability, and ecological roles. In this paper, we apply the concept of context dependency to mutualisms among bark beetles and fungi that span a variety of life strategies and exposures to environmental variability. Bark beetles and their mutualist fungi co-construct a niche based on by-product benefits that allows them to exist in a resource that is otherwise intractable or inaccessible. For the closest of these partnerships, this has resulted in some of the most influential agents of forest mortality in conifer forests worldwide. Understanding these symbioses is key to understanding their influence on forest structure and dynamics and responses to change. We found no evidence that bark beetle mutualisms change in sign as conditions vary, only in magnitude, and that the "closest" (and most environmentally influential) of these partnerships have evolved behaviors and mechanisms to reduce context-dependency and stabilize benefit delivery. The bark beetle-fungus symbioses most likely to slide along a mutualism-antagonism continuum are those involving loosely associated facultative symbionts that may provide benefits under some circumstances and that are horizontally transmitted by the beetle host. Additionally, some symbiotic fungi are never mutualists - these "third party" fungi are exploiters and may shift from commensalism to antagonism depending on environmental context. Our assessment indicates that a careful differentiation between bark beetle-fungus partnerships is crucial to understanding how they influence forests and respond to environmental variability.
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Affiliation(s)
- Diana L Six
- Department of Ecosystem and Conservation Science, The University of Montana, Missoula, MT, United States
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17
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Denison RF. Legume-imposed selection for more-efficient symbiotic rhizobia. Proc Natl Acad Sci U S A 2021; 118:e2107033118. [PMID: 33972460 PMCID: PMC8179168 DOI: 10.1073/pnas.2107033118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- R Ford Denison
- Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN 55108
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18
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Quides KW, Salaheldine F, Jariwala R, Sachs JL. Dysregulation of host-control causes interspecific conflict over host investment into symbiotic organs. Evolution 2021; 75:1189-1200. [PMID: 33521949 DOI: 10.1111/evo.14173] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 10/31/2020] [Accepted: 01/08/2021] [Indexed: 12/14/2022]
Abstract
Microbial mutualists provide substantial benefits to hosts that feed back to enhance the fitness of the associated microbes. In many systems, beneficial microbes colonize symbiotic organs, specialized host structures that house symbionts and mediate resources exchanged between parties. Mutualisms are characterized by net benefits exchanged among members of different species, however, inequalities in the magnitude of these exchanges could result in evolutionary conflict, destabilizing the mutualism. We investigated joint fitness effects of root nodule formation, the symbiotic organ of legumes that house nitrogen-fixing rhizobia in planta. We quantified host and symbiont fitness parameters dependent on the number of nodules formed using near-isogenic Lotus japonicus and Mesorhizobium loti mutants, respectively. Empirically estimated fitness functions suggest that legume and rhizobia fitness is aligned as the number of nodules formed increases from zero until the host optimum is reached, a point where aligned fitness interests shift to diverging fitness interests between host and symbiont. However, fitness conflict was only inferred when analyzing wild-type hosts along with their mutants dysregulated for control over nodule formation. These data demonstrate that to avoid conflict, hosts must tightly regulate investment into symbiotic organs maximizing their benefit to cost ratio of associating with microbes.
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Affiliation(s)
- Kenjiro W Quides
- Department of Evolution Ecology and Organismal Biology, University of California, Riverside, California, 92521, USA.,Current Institution: Schmid College of Science and Technology, Chapman University, Orange, California, USA
| | - Fathi Salaheldine
- Department of Evolution Ecology and Organismal Biology, University of California, Riverside, California, 92521, USA
| | - Ruchi Jariwala
- Department of Evolution Ecology and Organismal Biology, University of California, Riverside, California, 92521, USA
| | - Joel L Sachs
- Department of Evolution Ecology and Organismal Biology, University of California, Riverside, California, 92521, USA.,Institute for Integrative Genome Biology, University of California, Riverside, California, USA
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19
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Wendlandt CE, Helliwell E, Roberts M, Nguyen KT, Friesen ML, von Wettberg E, Price P, Griffitts JS, Porter SS. Decreased coevolutionary potential and increased symbiont fecundity during the biological invasion of a legume-rhizobium mutualism. Evolution 2021; 75:731-747. [PMID: 33433925 DOI: 10.1111/evo.14164] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 10/08/2020] [Accepted: 12/07/2020] [Indexed: 12/20/2022]
Abstract
Although most invasive species engage in mutualism, we know little about how mutualism evolves as partners colonize novel environments. Selection on cooperation and standing genetic variation for mutualism traits may differ between a mutualism's invaded and native ranges, which could alter cooperation and coevolutionary dynamics. To test for such differences, we compare mutualism traits between invaded- and native-range host-symbiont genotype combinations of the weedy legume, Medicago polymorpha, and its nitrogen-fixing rhizobium symbiont, Ensifer medicae, which have coinvaded North America. We find that mutualism benefits for plants are indistinguishable between invaded- and native-range symbioses. However, rhizobia gain greater fitness from invaded-range mutualisms than from native-range mutualisms, and this enhancement of symbiont fecundity could increase the mutualism's spread by increasing symbiont availability during plant colonization. Furthermore, mutualism traits in invaded-range symbioses show lower genetic variance and a simpler partitioning of genetic variance between host and symbiont sources, compared to native-range symbioses. This suggests that biological invasion has reduced mutualists' potential to respond to coevolutionary selection. Additionally, rhizobia bearing a locus (hrrP) that can enhance symbiotic fitness have more exploitative phenotypes in invaded-range than in native-range symbioses. These findings highlight the impacts of biological invasion on the evolution of mutualistic interactions.
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Affiliation(s)
- Camille E Wendlandt
- School of Biological Sciences, Washington State University, Vancouver, Washington
| | - Emily Helliwell
- School of Biological Sciences, Washington State University, Vancouver, Washington
| | - Miles Roberts
- School of Biological Sciences, Washington State University, Vancouver, Washington
| | - Kyle T Nguyen
- School of Biological Sciences, Washington State University, Vancouver, Washington
| | - Maren L Friesen
- Department of Plant Pathology, Department of Crop and Soil Sciences, Washington State University, Pullman, Washington
| | - Eric von Wettberg
- Department of Plant and Soil Science, Gund Institute for the Environment, University of Vermont, Burlington, Vermont
| | - Paul Price
- Department of Biology, Eastern Michigan University, Ypsilanti, Michigan
| | - Joel S Griffitts
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, Utah
| | - Stephanie S Porter
- School of Biological Sciences, Washington State University, Vancouver, Washington
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20
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O'Brien AM, Jack CN, Friesen ML, Frederickson ME. Whose trait is it anyways? Coevolution of joint phenotypes and genetic architecture in mutualisms. Proc Biol Sci 2021; 288:20202483. [PMID: 33434463 DOI: 10.1098/rspb.2020.2483] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Evolutionary biologists typically envision a trait's genetic basis and fitness effects occurring within a single species. However, traits can be determined by and have fitness consequences for interacting species, thus evolving in multiple genomes. This is especially likely in mutualisms, where species exchange fitness benefits and can associate over long periods of time. Partners may experience evolutionary conflict over the value of a multi-genomic trait, but such conflicts may be ameliorated by mutualism's positive fitness feedbacks. Here, we develop a simulation model of a host-microbe mutualism to explore the evolution of a multi-genomic trait. Coevolutionary outcomes depend on whether hosts and microbes have similar or different optimal trait values, strengths of selection and fitness feedbacks. We show that genome-wide association studies can map joint traits to loci in multiple genomes and describe how fitness conflict and fitness feedback generate different multi-genomic architectures with distinct signals around segregating loci. Partner fitnesses can be positively correlated even when partners are in conflict over the value of a multi-genomic trait, and conflict can generate strong mutualistic dependency. While fitness alignment facilitates rapid adaptation to a new optimum, conflict maintains genetic variation and evolvability, with implications for applied microbiome science.
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Affiliation(s)
- Anna M O'Brien
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
| | - Chandra N Jack
- Department of Plant Pathology, Washington State University, Pullman, Washington, USA
| | - Maren L Friesen
- Department of Plant Pathology, Washington State University, Pullman, Washington, USA.,Department of Crop and Soil Sciences, Washington State University, Pullman, Washington, USA
| | - Megan E Frederickson
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
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21
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Li R, Feng Y, Chen H, Zhang C, Huang Y, Chen L, Hao Q, Cao D, Yuan S, Zhou X. Whole-Genome Sequencing of Bradyrhizobium diazoefficiens 113-2 and Comparative Genomic Analysis Provide Molecular Insights Into Species Specificity and Host Specificity. Front Microbiol 2020; 11:576800. [PMID: 33329441 PMCID: PMC7709874 DOI: 10.3389/fmicb.2020.576800] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Accepted: 10/20/2020] [Indexed: 11/24/2022] Open
Abstract
In the present study, we sequenced the complete genome of Bradyrhizobium diazoefficiens 113-2. The genomic characteristics of six selected rhizobial strains (two fast-growing rhizobia, two medium-slow-growing rhizobia and two slow-growing rhizobia) with four different legume hosts were analyzed by comparative genomic analysis. Genomes of B. diazoefficiens 113-2 and B. diazoefficiens USDA110 were found to share a large synteny blocks and a high ANI value, supporting 113-2 as a strain of B. diazoefficiens. 5,455 singletons and 11,656 clusters were identified among the six rhizobia genomes, and most of the pair-wise comparisons clusters were shared by the two genomes of strains in the same genus. Similar genus-specific gene numbers in the assigned COG functional terms were present in the two strains of the same genus, while the numbers were decreased with the increase of growth rate in most of the COG terms. KEGG pathway analysis of B. diazoefficiens 113-2 suggested that the rhizobial genes in ABC transporters and Two-Component system were mainly species-specific. Besides, the candidate genes related to secretion system and surface polysaccharides biosynthesis in the genomes of the six strains were explored and compared. 39 nodulation gene families, 12 nif gene families and 10 fix gene families in the genomes of these six strains were identified, and gene classes in most of gene families and the types and total gene numbers of gene families were substantially different among these six genomes. We also performed synteny analyses for above-mentioned nod, nif, and fix gene groupings, and selected NodW, NolK, NoeJ, NifB, FixK, and FixJ gene families to perform phylogeny analyses. Our results provided valuable molecular insights into species specificity and host specificity. The genetic information responsible for host specificity will play important roles in expanding the host range of rhizobia among legumes, which might provide new clues for the understanding of the genetic determinants of non-legume-rhizobium symbiosis.
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Affiliation(s)
- Rong Li
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs of PRC, Oil Crops Research Institute of Chinese Academy of Agriculture Sciences, Wuhan, China
| | - Yong Feng
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
| | - Haifeng Chen
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs of PRC, Oil Crops Research Institute of Chinese Academy of Agriculture Sciences, Wuhan, China
| | - Chanjuan Zhang
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs of PRC, Oil Crops Research Institute of Chinese Academy of Agriculture Sciences, Wuhan, China
| | - Yi Huang
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs of PRC, Oil Crops Research Institute of Chinese Academy of Agriculture Sciences, Wuhan, China
| | - Limiao Chen
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs of PRC, Oil Crops Research Institute of Chinese Academy of Agriculture Sciences, Wuhan, China
| | - Qingnan Hao
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs of PRC, Oil Crops Research Institute of Chinese Academy of Agriculture Sciences, Wuhan, China
| | - Dong Cao
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs of PRC, Oil Crops Research Institute of Chinese Academy of Agriculture Sciences, Wuhan, China
| | - Songli Yuan
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs of PRC, Oil Crops Research Institute of Chinese Academy of Agriculture Sciences, Wuhan, China
| | - Xinan Zhou
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs of PRC, Oil Crops Research Institute of Chinese Academy of Agriculture Sciences, Wuhan, China
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22
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Bamba M, Aoki S, Kajita T, Setoguchi H, Watano Y, Sato S, Tsuchimatsu T. Massive rhizobial genomic variation associated with partner quality in Lotus-Mesorhizobium symbiosis. FEMS Microbiol Ecol 2020; 96:5917975. [PMID: 33016310 DOI: 10.1093/femsec/fiaa202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 09/29/2020] [Indexed: 11/14/2022] Open
Abstract
Variation in partner quality is commonly observed in diverse cooperative relationships, despite the theoretical prediction that selection favoring high-quality partners should eliminate such variation. Here, we investigated how genetic variation in partner quality could be maintained in the nitrogen-fixing mutualism between Lotus japonicus and Mesorhizobium bacteria. We reconstructed de novo assembled full-genome sequences from nine rhizobial symbionts, finding massive variation in the core genome and the similar symbiotic islands, indicating recent horizontal gene transfer (HGT) of the symbiosis islands into diverse Mesorhizobium lineages. A cross-inoculation experiment using 9 sequenced rhizobial symbionts and 15 L. japonicus accessions revealed extensive quality variation represented by plant growth phenotypes, including genotype-by-genotype interactions. Variation in quality was not associated with the presence/absence variation in known symbiosis-related genes in the symbiosis island; rather, it showed significant correlation with the core genome variation. Given the recurrent HGT of the symbiosis islands into diverse Mesorhizobium strains, local Mesorhizobium communities could serve as a major source of variation for core genomes, which might prevent variation in partner quality from fixing, even in the presence of selection favoring high-quality partners. These findings highlight the novel role of HGT of symbiosis islands in maintaining partner quality variation in the legume-rhizobia symbiosis.
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Affiliation(s)
- Masaru Bamba
- Department of Biology (Frontier Science Program), Graduate School of Science and Engineering, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan.,Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
| | - Seishiro Aoki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Tadashi Kajita
- Iriomote Station, Tropical Biosphere Research Center, The University of the Ryukyus, 870 Uehara, Taketomi-cho, Yaeyama-gun, Okinawa 907-1541, Japan
| | - Hiroaki Setoguchi
- Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-nihonmatsu-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yasuyuki Watano
- Department of Biology, Graduate School of Science, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan
| | - Shusei Sato
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
| | - Takashi Tsuchimatsu
- Department of Biology, Graduate School of Science, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan.,Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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23
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Chomicki G, Kiers ET, Renner SS. The Evolution of Mutualistic Dependence. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2020. [DOI: 10.1146/annurev-ecolsys-110218-024629] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
While the importance of mutualisms across the tree of life is recognized, it is not understood why some organisms evolve high levels of dependence on mutualistic partnerships, while other species remain autonomous or retain or regain minimal dependence on partners. We identify four main pathways leading to the evolution of mutualistic dependence. Then, we evaluate current evidence for three predictions: ( a) Mutualisms with different levels of dependence have distinct stabilizing mechanisms against exploitation and cheating, ( b) less dependent mutualists will return to autonomy more often than those that are highly dependent, and ( c) obligate mutualisms should be less context dependent than facultative ones. Although we find evidence supporting all three predictions, we stress that mutualistic partners follow diverse paths toward—and away from—dependence. We also highlight the need to better examine asymmetry in partner dependence. Recognizing how variation in dependence influences the stability, breakdown, and context dependence of mutualisms generates new hypotheses regarding how and why the benefits of mutualistic partnerships differ over time and space.
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Affiliation(s)
- Guillaume Chomicki
- Department of Bioscience, Durham University, Durham DH1 3LE, United Kingdom
| | - E. Toby Kiers
- Department of Ecological Science, Vrije Universiteit, 1081 HV Amsterdam, The Netherlands
| | - Susanne S. Renner
- Systematic Botany and Mycology, Department of Biology, University of Munich (LMU), 80638 Munich, Germany
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24
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Batstone RT, O’Brien AM, Harrison TL, Frederickson ME. Experimental evolution makes microbes more cooperative with their local host genotype. Science 2020; 370:476-478. [DOI: 10.1126/science.abb7222] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 08/31/2020] [Indexed: 12/14/2022]
Affiliation(s)
- Rebecca T. Batstone
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL 61801, USA
| | - Anna M. O’Brien
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
- Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, ON M5S 3G8, Canada
| | - Tia L. Harrison
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
| | - Megan E. Frederickson
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, ON M5S 3B2, Canada
- Radcliffe Institute for Advanced Study, Harvard University, Cambridge, MA 02138, USA
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25
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Oono R, Muller KE, Ho R, Jimenez Salinas A, Denison RF. How do less-expensive nitrogen alternatives affect legume sanctions on rhizobia? Ecol Evol 2020; 10:10645-10656. [PMID: 33072286 PMCID: PMC7548176 DOI: 10.1002/ece3.6718] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/29/2020] [Accepted: 07/29/2020] [Indexed: 01/28/2023] Open
Abstract
The evolutionary stability of mutualistic interactions involving multiple partners requires “sanctioning”–the ability to influence the fitness of each partner based on its respective contribution. Sanctions must be sensitive to even small differences if even slightly less‐beneficial partners could gain a fitness advantage by diverting resources away from the mutualistic service toward their own reproductive fitness. Here, we test whether legume hosts sanction even mediocre N2‐fixing rhizobial strains by influencing either nodule growth (which limits rhizobial cell numbers) or carbon accumulation (polyhydroxybutryate or PHB) per rhizobial cell. We also test whether sanctions depend on the availability of less‐expensive nitrogen alternatives, either as nitrate or coinoculation with a more‐efficient isogenic strain. We found that nitrate eliminated differences in nodule size between the mediocre and more‐efficient strains, suggesting that host sanctions were compromised. However, nitrate additions also decreased PHB accumulation by the mediocre strain, which may eliminate any fitness advantages of diverting resources from N2 fixation. Coinoculation with a more‐efficient strain could also compromise host sanctions if reduction in fitness from smaller nodules does not offset the potential fitness gain from greater PHB accumulation that we observed in the mediocre strain. Hence, a host's ability to sanction mediocre strains depends not only on alternative sources of nitrogen but also the relative importance of different components of rhizobial fitness.
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Affiliation(s)
- Ryoko Oono
- Department of Ecology, Evolution, and Marine Biology University of California Santa Barbara CA USA
| | - Katherine E Muller
- Department of Ecology, Evolution, and Behavior University of Minnesota - Twin Cities St. Paul MN USA.,Present address: School of Integrated Sciences Cornell University Ithaca NY USA
| | - Randy Ho
- Department of Ecology, Evolution, and Marine Biology University of California Santa Barbara CA USA
| | - Andres Jimenez Salinas
- Department of Ecology, Evolution, and Marine Biology University of California Santa Barbara CA USA.,Department of Chemistry and Biochemistry San Diego State University San Diego CA USA
| | - Robert Ford Denison
- Department of Ecology, Evolution, and Behavior University of Minnesota - Twin Cities St. Paul MN USA
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Liana T. Burghardt. THE NEW PHYTOLOGIST 2020; 228:24-25. [PMID: 33448399 DOI: 10.1111/nph.16869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
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Burghardt LT. Evolving together, evolving apart: measuring the fitness of rhizobial bacteria in and out of symbiosis with leguminous plants. THE NEW PHYTOLOGIST 2020; 228:28-34. [PMID: 31276218 DOI: 10.1111/nph.16045] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 06/20/2019] [Indexed: 05/11/2023]
Abstract
Most plant-microbe interactions are facultative, with microbes experiencing temporally and spatially variable selection. How this variation affects microbial evolution is poorly understood. Given its tractability and ecological and agricultural importance, the legume-rhizobia nitrogen-fixing symbiosis is a powerful model for identifying traits and genes underlying bacterial fitness. New technologies allow high-throughput measurement of the relative fitness of bacterial mutants, strains and species in mixed inocula in the host, rhizosphere and soil environments. I consider how host genetic variation (G × G), other environmental factors (G × E), and host life-cycle variation may contribute to the maintenance of genetic variation and adaptive trajectories of rhizobia - and, potentially, other facultative symbionts. Lastly, I place these findings in the context of developing beneficial inoculants in a changing climate.
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Affiliation(s)
- Liana T Burghardt
- Department of Plant and Microbial Biology, University of Minnesota, 140 Gortner Laboratory, 1479 Gortner Avenue, St Paul, MN, 55108, USA
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de la Fuente Cantó C, Simonin M, King E, Moulin L, Bennett MJ, Castrillo G, Laplaze L. An extended root phenotype: the rhizosphere, its formation and impacts on plant fitness. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:951-964. [PMID: 32324287 DOI: 10.1111/tpj.14781] [Citation(s) in RCA: 90] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 04/03/2020] [Accepted: 04/09/2020] [Indexed: 05/13/2023]
Abstract
Plants forage soil for water and nutrients, whose distribution is patchy and often dynamic. To improve their foraging activities, plants have evolved mechanisms to modify the physicochemical properties and microbial communities of the rhizosphere, i.e. the soil compartment under the influence of the roots. This dynamic interplay in root-soil-microbiome interactions creates emerging properties that impact plant nutrition and health. As a consequence, the rhizosphere can be considered an extended root phenotype, a manifestation of the effects of plant genes on their environment inside and/or outside of the organism. Here, we review current understanding of how plants shape the rhizosphere and the benefits it confers to plant fitness. We discuss future research challenges and how applying their solutions in crops will enable us to harvest the benefits of the extended root phenotype.
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Affiliation(s)
- Carla de la Fuente Cantó
- UMR DIADE, Université de Montpellier, Institut de Recherche pour le Développement (IRD), Montpellier, France
| | - Marie Simonin
- UMR DIADE, Université de Montpellier, Institut de Recherche pour le Développement (IRD), Montpellier, France
- UMR IPME, IRD, Cirad, Université de Montpellier, Montpellier, France
- IRHS-UMR1345, Université d'Angers, INRAE, Institut Agro, SFR 4207 QuaSaV, 49071, Beaucouzé, France
| | - Eoghan King
- UMR IPME, IRD, Cirad, Université de Montpellier, Montpellier, France
| | - Lionel Moulin
- UMR IPME, IRD, Cirad, Université de Montpellier, Montpellier, France
| | - Malcolm J Bennett
- Future Food Beacon of Excellence, School of Biosciences, University of Nottingham, Sutton Bonington, UK
| | - Gabriel Castrillo
- Future Food Beacon of Excellence, School of Biosciences, University of Nottingham, Sutton Bonington, UK
| | - Laurent Laplaze
- UMR DIADE, Université de Montpellier, Institut de Recherche pour le Développement (IRD), Montpellier, France
- Laboratoire Mixte International Adaptation des Plantes et Microorganismes Associés aux Stress Environnementaux (LAPSE), Dakar, Senegal
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29
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O'Brien AM, Laurich J, Lash E, Frederickson ME. Mutualistic Outcomes Across Plant Populations, Microbes, and Environments in the Duckweed Lemna minor. MICROBIAL ECOLOGY 2020; 80:384-397. [PMID: 32123959 DOI: 10.1007/s00248-019-01452-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 10/03/2019] [Indexed: 06/10/2023]
Abstract
The picture emerging from the rapidly growing literature on host-associated microbiota is that host traits and fitness often depend on interactive effects of host genotype, microbiota, and abiotic environment. However, testing interactive effects typically requires large, multi-factorial experiments and thus remains challenging in many systems. Furthermore, most studies of plant microbiomes focus on terrestrial hosts and microbes. Aquatic habitats may confer unique properties to microbiomes. We grew different populations of duckweed (Lemna minor), a floating aquatic plant, in three microbial treatments (adding no, "home", or "away" microbes) at two levels of zinc, a common water contaminant in urban areas, and measured both plant and microbial performance. Thus, we simultaneously manipulated plant source population, microbial community, and abiotic environment. We found strong effects of plant source, microbial treatment, and zinc on duckweed and microbial growth, with significant variation among duckweed genotypes and microbial communities. However, we found little evidence of interactive effects: zinc did not alter effects of host genotype or microbial community, and host genotype did not alter effects of microbial communities. Despite strong positive correlations between duckweed and microbe growth, zinc consistently decreased plant growth, but increased microbial growth. Furthermore, as in recent studies of terrestrial plants, microbial interactions altered a duckweed phenotype (frond aggregation). Our results suggest that duckweed source population, associated microbiome, and contaminant environment should all be considered for duckweed applications, such as phytoremediation. Lastly, we propose that duckweed microbes offer a robust experimental system for study of host-microbiota interactions under a range of environmental stresses.
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Affiliation(s)
- Anna M O'Brien
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada.
| | - Jason Laurich
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada
| | - Emma Lash
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada
| | - Megan E Frederickson
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada
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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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Cavassim MIA, Moeskjær S, Moslemi C, Fields B, Bachmann A, Vilhjálmsson BJ, Schierup MH, W. Young JP, Andersen SU. Symbiosis genes show a unique pattern of introgression and selection within a Rhizobium leguminosarum species complex. Microb Genom 2020; 6:e000351. [PMID: 32176601 PMCID: PMC7276703 DOI: 10.1099/mgen.0.000351] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 02/17/2020] [Indexed: 12/22/2022] Open
Abstract
Rhizobia supply legumes with fixed nitrogen using a set of symbiosis genes. These can cross rhizobium species boundaries, but it is unclear how many other genes show similar mobility. Here, we investigate inter-species introgression using de novo assembly of 196 Rhizobium leguminosarum sv. trifolii genomes. The 196 strains constituted a five-species complex, and we calculated introgression scores based on gene-tree traversal to identify 171 genes that frequently cross species boundaries. Rather than relying on the gene order of a single reference strain, we clustered the introgressing genes into four blocks based on population structure-corrected linkage disequilibrium patterns. The two largest blocks comprised 125 genes and included the symbiosis genes, a smaller block contained 43 mainly chromosomal genes, and the last block consisted of three genes with variable genomic location. All introgression events were likely mediated by conjugation, but only the genes in the symbiosis linkage blocks displayed overrepresentation of distinct, high-frequency haplotypes. The three genes in the last block were core genes essential for symbiosis that had, in some cases, been mobilized on symbiosis plasmids. Inter-species introgression is thus not limited to symbiosis genes and plasmids, but other cases are infrequent and show distinct selection signatures.
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Affiliation(s)
- Maria Izabel A. Cavassim
- Bioinformatics Research Centre, Aarhus University, Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Sara Moeskjær
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Camous Moslemi
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | | | - Asger Bachmann
- Bioinformatics Research Centre, Aarhus University, Aarhus, Denmark
| | | | | | | | - Stig U. Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
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32
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Doin de Moura GG, Remigi P, Masson-Boivin C, Capela D. Experimental Evolution of Legume Symbionts: What Have We Learnt? Genes (Basel) 2020; 11:E339. [PMID: 32210028 PMCID: PMC7141107 DOI: 10.3390/genes11030339] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 03/17/2020] [Accepted: 03/20/2020] [Indexed: 12/11/2022] Open
Abstract
Rhizobia, the nitrogen-fixing symbionts of legumes, are polyphyletic bacteria distributed in many alpha- and beta-proteobacterial genera. They likely emerged and diversified through independent horizontal transfers of key symbiotic genes. To replay the evolution of a new rhizobium genus under laboratory conditions, the symbiotic plasmid of Cupriavidus taiwanensis was introduced in the plant pathogen Ralstonia solanacearum, and the generated proto-rhizobium was submitted to repeated inoculations to the C. taiwanensis host, Mimosa pudica L.. This experiment validated a two-step evolutionary scenario of key symbiotic gene acquisition followed by genome remodeling under plant selection. Nodulation and nodule cell infection were obtained and optimized mainly via the rewiring of regulatory circuits of the recipient bacterium. Symbiotic adaptation was shown to be accelerated by the activity of a mutagenesis cassette conserved in most rhizobia. Investigating mutated genes led us to identify new components of R. solanacearum virulence and C. taiwanensis symbiosis. Nitrogen fixation was not acquired in our short experiment. However, we showed that post-infection sanctions allowed the increase in frequency of nitrogen-fixing variants among a non-fixing population in the M. pudica-C. taiwanensis system and likely allowed the spread of this trait in natura. Experimental evolution thus provided new insights into rhizobium biology and evolution.
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Affiliation(s)
| | | | | | - Delphine Capela
- LIPM, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan 31320, France; (G.G.D.d.M.); (P.R.); (C.M.-B.)
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33
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O'Brien AM, Yu ZH, Luo DY, Laurich J, Passeport E, Frederickson ME. Resilience to multiple stressors in an aquatic plant and its microbiome. AMERICAN JOURNAL OF BOTANY 2020; 107:273-285. [PMID: 31879950 DOI: 10.1002/ajb2.1404] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 09/09/2019] [Indexed: 05/22/2023]
Abstract
PREMISE Outcomes of species interactions, especially mutualisms, are notoriously dependent on environmental context, and environments are changing rapidly. Studies have investigated how mutualisms respond to or ameliorate anthropogenic environmental changes, but most have focused on nutrient pollution or climate change and tested stressors one at a time. Relatively little is known about how mutualisms may be altered by or buffer the effects of multiple chemical contaminants, which differ fundamentally from nutrient or climate stressors and are especially widespread in aquatic habitats. METHODS We investigated the impacts of two contaminants on interactions between the duckweed Lemna minor and its microbiome. Sodium chloride (salt) and benzotriazole (a corrosion inhibitor) often co-occur in runoff to water bodies where duckweeds reside. We tested three L. minor genotypes with and without the culturable portion of their microbiome across field-realistic gradients of salt (3 levels) and benzotriazole (4 levels) in a fully factorial experiment (24 treatments, tested on each genotype) and measured plant and microbial growth. RESULTS Stressors had conditional effects. Salt decreased both plant and microbial growth and decreased plant survival more as benzotriazole concentrations increased. In contrast, benzotriazole did not affect microbial abundance and even benefited plants when salt and microbes were absent, perhaps due to biotransformation into growth-promoting compounds. Microbes did not ameliorate duckweed stressors; microbial inoculation increased plant growth, but not at high salt concentrations. CONCLUSIONS Our results suggest that multiple stressors matter when predicting responses of mutualisms to global change and that beneficial microbes may not always buffer hosts against stress.
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Affiliation(s)
- Anna M O'Brien
- Department of Ecology and Evolutionary Biology, University of Toronto
| | - Zhu Hao Yu
- Department of Chemical Engineering and Applied Chemistry, University of Toronto
| | - Dian-Ya Luo
- Department of Ecology and Evolutionary Biology, University of Toronto
| | - Jason Laurich
- Department of Ecology and Evolutionary Biology, University of Toronto
| | - Elodie Passeport
- Department of Chemical Engineering and Applied Chemistry, University of Toronto
- Department of Civil and Mineral Engineering, University of Toronto
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34
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Gano-Cohen KA, Wendlandt CE, Al Moussawi K, Stokes PJ, Quides KW, Weisberg AJ, Chang JH, Sachs JL. Recurrent mutualism breakdown events in a legume rhizobia metapopulation. Proc Biol Sci 2020; 287:20192549. [PMID: 31992172 DOI: 10.1098/rspb.2019.2549] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Bacterial mutualists generate major fitness benefits for eukaryotes, reshaping the host phenotype and its interactions with the environment. Yet, microbial mutualist populations are predicted to generate mutants that defect from providing costly services to hosts while maintaining the capacity to exploit host resources. Here, we examined the mutualist service of symbiotic nitrogen fixation in a metapopulation of root-nodulating Bradyrhizobium spp. that associate with the native legume Acmispon strigosus. We quantified mutualism traits of 85 Bradyrhizobium isolates gathered from a 700 km transect in California spanning 10 sampled A. strigosus populations. We clonally inoculated each Bradyrhizobium isolate onto A. strigosus hosts and quantified nodulation capacity and net effects of infection, including host growth and isotopic nitrogen concentration. Six Bradyrhizobium isolates from five populations were categorized as ineffective because they formed nodules but did not enhance host growth via nitrogen fixation. Six additional isolates from three populations failed to form root nodules. Phylogenetic reconstruction inferred two types of mutualism breakdown, including three to four independent losses of effectiveness and five losses of nodulation capacity on A. strigosus. The evolutionary and genomic drivers of these mutualism breakdown events remain poorly understood.
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Affiliation(s)
- Kelsey A Gano-Cohen
- Department of Microbiology and Plant Pathology, University of California, Riverside, CA, USA
| | - Camille E Wendlandt
- Department of Botany and Plant Sciences, University of California, Riverside, CA, USA
| | - Khadija Al Moussawi
- Department of Evolution Ecology and Organismal Biology, University of California, Riverside, CA, USA
| | - Peter J Stokes
- Department of Botany and Plant Sciences, University of California, Riverside, CA, USA
| | - Kenjiro W Quides
- Department of Evolution Ecology and Organismal Biology, University of California, Riverside, CA, USA
| | - Alexandra J Weisberg
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA
| | - Jeff H Chang
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA
| | - Joel L Sachs
- Department of Microbiology and Plant Pathology, University of California, Riverside, CA, USA.,Department of Botany and Plant Sciences, University of California, Riverside, CA, USA.,Department of Evolution Ecology and Organismal Biology, University of California, Riverside, CA, USA.,Institute for Integrative Genome Biology, University of California, Riverside, CA, USA
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35
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More Than a Functional Group: Diversity within the Legume–Rhizobia Mutualism and Its Relationship with Ecosystem Function. DIVERSITY-BASEL 2020. [DOI: 10.3390/d12020050] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Studies of biodiversity and ecosystem function (BEF) have long focused on the role of nitrogen (N)-fixing legumes as a functional group that occupies a distinct and important niche relative to other plants. Because of their relationship with N-fixing rhizobial bacteria, these legumes access a different pool of N than other plants and therefore directly contribute to increases in productivity and N-cycling. Despite their recognized importance in the BEF literature, the field has not moved far beyond investigating the presence/absence of the legume functional group in species mixtures. Here, we synthesize existing information on how the diversity (species richness and functional diversity) of both legumes and the rhizobia that they host impact ecosystem functions, such as nitrogen fixation and primary productivity. We also discuss the often-overlooked reciprocal direction of the BEF relationship, whereby ecosystem function can influence legume and rhizobial diversity. We focus on BEF mechanisms of selection, complementarity, facilitation, competitive interference, and dilution effects to explain how diversity in the legume–rhizobia mutualism can have either positive or negative effects on ecosystem function—mechanisms that can operate at scales from rhizobial communities affecting individual legume functions to legume communities affecting landscape-scale ecosystem functions. To fully understand the relationship between biodiversity and ecosystem function, we must incorporate the full diversity of this mutualism and its reciprocal relationship with ecosystem function into our evolving BEF framework.
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36
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Frederickson ME. No selection for cheating in a natural meta‐population of rhizobia. Ecol Lett 2020; 23:409-411. [DOI: 10.1111/ele.13293] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 05/11/2019] [Indexed: 01/24/2023]
Affiliation(s)
- Megan E. Frederickson
- Department of Ecology and Evolutionary Biology University of Toronto Toronto ONM5S 3B2Canada
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37
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Rebolleda-Gómez M, Wood CW. Unclear Intentions: Eavesdropping in Microbial and Plant Systems. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00385] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Adaptive partner recruitment can help maintain an intra-guild diversity in mutualistic systems. J Theor Biol 2019; 478:40-47. [PMID: 31220467 DOI: 10.1016/j.jtbi.2019.06.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 06/13/2019] [Accepted: 06/17/2019] [Indexed: 11/20/2022]
Abstract
Mutualisms between assemblages of multiple species or strains (guilds) are considered unstable because of positive feedback between the guilds. Previous studies suggest that negative inter-guild feedback due to asymmetry in the exchange of benefits between the guilds can stabilize them, but preferential association for more beneficial partners may reduce such asymmetry and strengthen the positive inter-guild feedback. Here I develop a replicator dynamics model for mutualistic systems between two host and two symbiont strains to investigate conditions that stabilize mutualisms when feedback between host-symbiont guilds is positive. I assume that one symbiont strain is mutualistic for one host strain but parasitic for the other, whereas the other symbiont strain is the opposite. Hosts recruit their symbionts from the environment and discriminately offer them resources (partner preference), and only mutualistic symbionts return benefits to their hosts. I show that the two host and symbiont strains can coexist under strong partner preference by hosts if they adaptively adjust the number of associating symbionts, even when the intra-host strain competition is not so strong. Interestingly, there can be a stable coexistence equilibrium also under weak partner preference, but it disappears under intermediate levels of partner preference.
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Revealing the Draft Genome Sequence of Bradyrhizobium sp. Strain USDA 3458, an Effective Symbiotic Diazotroph Isolated from Cowpea ( Vigna unguiculata) Genotype IT82E-16. Microbiol Resour Announc 2019; 8:8/38/e00813-19. [PMID: 31537665 PMCID: PMC6753269 DOI: 10.1128/mra.00813-19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pairing plants with plant growth-promoting bacteria is critical to the future of agriculture. Bradyrhizobium sp. strain USDA 3458 isolated from Vigna unguiculata (cowpea) paired with cowpea genotype IT82E-16 represents a novel combination in arid regions. Here, we report the draft genome sequence of strain USDA 3458. Pairing plants with plant growth-promoting bacteria is critical to the future of agriculture. Bradyrhizobium sp. strain USDA 3458 isolated from Vigna unguiculata (cowpea) paired with cowpea genotype IT82E-16 represents a novel combination in arid regions. Here, we report the draft genome sequence of strain USDA 3458.
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Deciphering the Symbiotic Plant Microbiome: Translating the Most Recent Discoveries on Rhizobia for the Improvement of Agricultural Practices in Metal-Contaminated and High Saline Lands. AGRONOMY-BASEL 2019. [DOI: 10.3390/agronomy9090529] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Rhizosphere and plant-associated microorganisms have been intensely studied for their beneficial effects on plant growth and health. These mainly include nitrogen-fixing bacteria (NFB) and plant-growth promoting rhizobacteria (PGPR). This beneficial fraction is involved in major functions such as plant nutrition and plant resistance to biotic and abiotic stresses, which include water deficiency and heavy-metal contamination. Consequently, crop yield emerges as the net result of the interactions between the plant genome and its associated microbiome. Here, we provide a review covering recent studies on PGP rhizobia as effective inoculants for agricultural practices in harsh soil, and we propose models for inoculant combinations and genomic manipulation strategies to improve crop yield.
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Elucidation of the Genome of Bradyrhizobium sp. Strain USDA 3456, a Historic Agricultural Diazotroph from Cowpea (Vigna unguiculata). Microbiol Resour Announc 2019; 8:8/33/e00812-19. [PMID: 31416877 PMCID: PMC6696652 DOI: 10.1128/mra.00812-19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bradyrhizobium sp. strain USDA 3456 is a historic strain from the United States Department of Agriculture (USDA) Agricultural Research Service (ARS) National Rhizobium Germplasm Collection isolated from Vigna unguiculata (cowpea) in 1966. Strain USDA 3456 has been utilized in global agricultural applications, including improving soil nitrogen fertility. The draft genome sequence here provides a genetic reference of a novel diazotroph. Bradyrhizobium sp. strain USDA 3456 is a historic strain from the United States Department of Agriculture (USDA) Agricultural Research Service (ARS) National Rhizobium Germplasm Collection isolated from Vigna unguiculata (cowpea) in 1966. Strain USDA 3456 has been utilized in global agricultural applications, including improving soil nitrogen fertility. The draft genome sequence here provides a genetic reference of a novel diazotroph.
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Greenlon A, Chang PL, Damtew ZM, Muleta A, Carrasquilla-Garcia N, Kim D, Nguyen HP, Suryawanshi V, Krieg CP, Yadav SK, Patel JS, Mukherjee A, Udupa S, Benjelloun I, Thami-Alami I, Yasin M, Patil B, Singh S, Sarma BK, von Wettberg EJB, Kahraman A, Bukun B, Assefa F, Tesfaye K, Fikre A, Cook DR. Global-level population genomics reveals differential effects of geography and phylogeny on horizontal gene transfer in soil bacteria. Proc Natl Acad Sci U S A 2019; 116:15200-15209. [PMID: 31285337 PMCID: PMC6660780 DOI: 10.1073/pnas.1900056116] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Although microorganisms are known to dominate Earth's biospheres and drive biogeochemical cycling, little is known about the geographic distributions of microbial populations or the environmental factors that pattern those distributions. We used a global-level hierarchical sampling scheme to comprehensively characterize the evolutionary relationships and distributional limitations of the nitrogen-fixing bacterial symbionts of the crop chickpea, generating 1,027 draft whole-genome sequences at the level of bacterial populations, including 14 high-quality PacBio genomes from a phylogenetically representative subset. We find that diverse Mesorhizobium taxa perform symbiosis with chickpea and have largely overlapping global distributions. However, sampled locations cluster based on the phylogenetic diversity of Mesorhizobium populations, and diversity clusters correspond to edaphic and environmental factors, primarily soil type and latitude. Despite long-standing evolutionary divergence and geographic isolation, the diverse taxa observed to nodulate chickpea share a set of integrative conjugative elements (ICEs) that encode the major functions of the symbiosis. This symbiosis ICE takes 2 forms in the bacterial chromosome-tripartite and monopartite-with tripartite ICEs confined to a broadly distributed superspecies clade. The pairwise evolutionary relatedness of these elements is controlled as much by geographic distance as by the evolutionary relatedness of the background genome. In contrast, diversity in the broader gene content of Mesorhizobium genomes follows a tight linear relationship with core genome phylogenetic distance, with little detectable effect of geography. These results illustrate how geography and demography can operate differentially on the evolution of bacterial genomes and offer useful insights for the development of improved technologies for sustainable agriculture.
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Affiliation(s)
- Alex Greenlon
- Department of Plant Pathology, University of California, Davis, CA 95616
| | - Peter L Chang
- Department of Plant Pathology, University of California, Davis, CA 95616
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089
| | - Zehara Mohammed Damtew
- College of Natural Sciences, Addis Ababa University, Addis Ababa, 32853 Ethiopia
- Debre Zeit Agricultural Research Center, Ethiopian Institute for Agricultural Research, Bishoftu, Ethiopia
| | - Atsede Muleta
- College of Natural Sciences, Addis Ababa University, Addis Ababa, 32853 Ethiopia
| | | | - Donghyun Kim
- International Crop Research Institute for the Semi-Arid Tropics, Hyderabad 502324, India
| | - Hien P Nguyen
- United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, 183-8509 Tokyo, Japan
| | - Vasantika Suryawanshi
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089
| | - Christopher P Krieg
- Department of Biological Sciences, Florida International University, Miami, FL 33199
| | - Sudheer Kumar Yadav
- Department of Mycology and Plant Pathology, Banaras Hindu University, Varanasi 221005, India
| | - Jai Singh Patel
- Department of Mycology and Plant Pathology, Banaras Hindu University, Varanasi 221005, India
| | - Arpan Mukherjee
- Department of Mycology and Plant Pathology, Banaras Hindu University, Varanasi 221005, India
| | - Sripada Udupa
- Biodiversity and Integrated Gene Management Program, International Center for Agricultural Research in the Dry Areas, 10112 Rabat, Morocco
| | - Imane Benjelloun
- Institute National de la Recherche Agronomique, 10100 Rabat, Morocco
| | - Imane Thami-Alami
- Institute National de la Recherche Agronomique, 10100 Rabat, Morocco
| | | | - Bhuvaneshwara Patil
- Department of Genetics and Plant Breeding, University of Agricultural Sciences, Dharwad 580001, India
| | - Sarvjeet Singh
- Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana 141027, India
| | - Birinchi Kumar Sarma
- Department of Mycology and Plant Pathology, Banaras Hindu University, Varanasi 221005, India
| | - Eric J B von Wettberg
- Department of Biological Sciences, Florida International University, Miami, FL 33199
- Department of Plant and Soil Science, University of Vermont, Burlington, VT 05405
| | - Abdullah Kahraman
- Department of Field Crops, Faculty of Agriculture, Harran University, 63100 Sanliurfa, Turkey
| | - Bekir Bukun
- Department of Plant Protection, Dicle University, 21280 Diyarbakir, Turkey
| | - Fassil Assefa
- College of Natural Sciences, Addis Ababa University, Addis Ababa, 32853 Ethiopia
| | - Kassahun Tesfaye
- College of Natural Sciences, Addis Ababa University, Addis Ababa, 32853 Ethiopia
| | - Asnake Fikre
- Debre Zeit Agricultural Research Center, Ethiopian Institute for Agricultural Research, Bishoftu, Ethiopia
| | - Douglas R Cook
- Department of Plant Pathology, University of California, Davis, CA 95616;
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Gibert A, Tozer W, Westoby M. Plant performance response to eight different types of symbiosis. THE NEW PHYTOLOGIST 2019; 222:526-542. [PMID: 30697746 DOI: 10.1111/nph.15392] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 07/07/2018] [Indexed: 06/09/2023]
Abstract
Almost all plant species interact with one or more symbioses somewhere within their distribution range. Bringing together plant trait data and growth responses to symbioses spanning 552 plant species, we provide for the first time on a large scale (597 studies) a quantitative synthesis on plant performance differences between eight major types of symbiosis, including mycorrhizas, N-fixing bacteria, fungal endophytes and ant-plant interactions. Frequency distributions of plant growth responses varied considerably between different types of symbiosis, in terms of both mean effect and 'risk', defined here as percentage of experiments reporting a negative effect of symbiosis on plants. Contrary to expectation, plant traits were poor predictors of growth response across and within all eight symbiotic associations. Our analysis showed no systematic additive effect when a host plant engaged in two functionally different symbioses. This synthesis suggests that plant species' ecological strategies have little effect in determining the influence of a symbiosis on host plant growth. Reliable quantification of differences in plant performance across symbioses will prove valuable for developing general hypotheses on how species become engaged in mutualisms without a guarantee of net returns.
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Affiliation(s)
- Anais Gibert
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Wade Tozer
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Mark Westoby
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia
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Bashandy SR, Abd‐Alla MH, Bagy MMK. Biological Nitrogen Fixation and Biofertilizers as Ideal Potential Solutions for Sustainable Agriculture. INTEGRATING GREEN CHEMISTRY AND SUSTAINABLE ENGINEERING 2019:343-396. [DOI: 10.1002/9781119509868.ch12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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45
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Gano‐Cohen KA, Wendlandt CE, Stokes PJ, Blanton MA, Quides KW, Zomorrodian A, Adinata ES, Sachs JL. Interspecific conflict and the evolution of ineffective rhizobia. Ecol Lett 2019; 22:914-924. [DOI: 10.1111/ele.13247] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 02/07/2019] [Indexed: 12/25/2022]
Affiliation(s)
- Kelsey A. Gano‐Cohen
- Department of Microbiology and Plant Pathology University of California Riverside CA USA
- Department of Evolution Ecology & Organismal Biology University of California Riverside CA USA
| | - Camille E. Wendlandt
- Department of Evolution Ecology & Organismal Biology University of California Riverside CA USA
- Department of Botany and Plant Sciences University of California Riverside CA USA
| | - Peter J. Stokes
- Department of Evolution Ecology & Organismal Biology University of California Riverside CA USA
| | - Mia A. Blanton
- Department of Evolution Ecology & Organismal Biology University of California Riverside CA USA
| | - Kenjiro W. Quides
- Department of Evolution Ecology & Organismal Biology University of California Riverside CA USA
| | - Avissa Zomorrodian
- Department of Evolution Ecology & Organismal Biology University of California Riverside CA USA
| | - Eunice S. Adinata
- Department of Evolution Ecology & Organismal Biology University of California Riverside CA USA
| | - Joel L. Sachs
- Department of Microbiology and Plant Pathology University of California Riverside CA USA
- Department of Evolution Ecology & Organismal Biology University of California Riverside CA USA
- Department of Botany and Plant Sciences University of California Riverside CA USA
- Institute for Integrative Genome Biology University of California Riverside CA USA
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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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Fagorzi C, Checcucci A, diCenzo GC, Debiec-Andrzejewska K, Dziewit L, Pini F, Mengoni A. Harnessing Rhizobia to Improve Heavy-Metal Phytoremediation by Legumes. Genes (Basel) 2018; 9:genes9110542. [PMID: 30413093 PMCID: PMC6266702 DOI: 10.3390/genes9110542] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 11/05/2018] [Accepted: 11/06/2018] [Indexed: 12/15/2022] Open
Abstract
Rhizobia are bacteria that can form symbiotic associations with plants of the Fabaceae family, during which they reduce atmospheric di-nitrogen to ammonia. The symbiosis between rhizobia and leguminous plants is a fundamental contributor to nitrogen cycling in natural and agricultural ecosystems. Rhizobial microsymbionts are a major reason why legumes can colonize marginal lands and nitrogen-deficient soils. Several leguminous species have been found in metal-contaminated areas, and they often harbor metal-tolerant rhizobia. In recent years, there have been numerous efforts and discoveries related to the genetic determinants of metal resistance by rhizobia, and on the effectiveness of such rhizobia to increase the metal tolerance of host plants. Here, we review the main findings on the metal resistance of rhizobia: the physiological role, evolution, and genetic determinants, and the potential to use native and genetically-manipulated rhizobia as inoculants for legumes in phytoremediation practices.
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Affiliation(s)
- Camilla Fagorzi
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy.
| | - Alice Checcucci
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy.
| | - George C diCenzo
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy.
| | - Klaudia Debiec-Andrzejewska
- Laboratory of Environmental Pollution Analysis, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
| | - Lukasz Dziewit
- Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
| | - Francesco Pini
- Department of Agri-food Production and Environmental Science, University of Florence, 50144 Florence, Italy.
| | - Alessio Mengoni
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy.
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Porter SS, Faber-Hammond J, Montoya AP, Friesen ML, Sackos C. Dynamic genomic architecture of mutualistic cooperation in a wild population of Mesorhizobium. ISME JOURNAL 2018; 13:301-315. [PMID: 30218020 PMCID: PMC6331556 DOI: 10.1038/s41396-018-0266-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 07/01/2018] [Accepted: 08/04/2018] [Indexed: 12/14/2022]
Abstract
Research on mutualism seeks to explain how cooperation can be maintained when uncooperative mutants co-occur with cooperative kin. Gains and losses of the gene modules required for cooperation punctuate symbiont phylogenies and drive lifestyle transitions between cooperative symbionts and uncooperative free-living lineages over evolutionary time. Yet whether uncooperative symbionts commonly evolve from within cooperative symbiont populations or from within distantly related lineages with antagonistic or free-living lifestyles (i.e., third-party mutualism exploiters or parasites), remains controversial. We use genomic data to show that genotypes that differ in the presence or absence of large islands of symbiosis genes are common within a single wild recombining population of Mesorhizobium symbionts isolated from host tissues and are an important source of standing heritable variation in cooperation in this population. In a focal population of Mesorhizobium, uncooperative variants that lack a symbiosis island segregate at 16% frequency in nodules, and genome size and symbiosis gene number are positively correlated with cooperation. This finding contrasts with the genomic architecture of variation in cooperation in other symbiont populations isolated from host tissues in which the islands of genes underlying cooperation are ubiquitous and variation in cooperation is primarily driven by allelic substitution and individual gene gain and loss events. Our study demonstrates that uncooperative mutants within mutualist populations can comprise a significant component of genetic variation in nature, providing biological rationale for models and experiments that seek to explain the maintenance of mutualism in the face of non-cooperators.
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Affiliation(s)
- Stephanie S Porter
- School of Biological Sciences, Washington State University, Vancouver, WA, 98686, USA.
| | - Joshua Faber-Hammond
- School of Biological Sciences, Washington State University, Vancouver, WA, 98686, USA
| | - Angeliqua P Montoya
- School of Biological Sciences, Washington State University, Vancouver, WA, 98686, USA
| | - Maren L Friesen
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA.,Department of Plant Pathology, Washington State University, Pullman, WA, 99164, USA.,Department of Crop and Soil Sciences, Washington State University, Pullman, WA, 99164, USA
| | - Cynthia Sackos
- School of Biological Sciences, Washington State University, Vancouver, WA, 98686, USA
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Sachs JL, Quides KW, Wendlandt CE. Legumes versus rhizobia: a model for ongoing conflict in symbiosis. THE NEW PHYTOLOGIST 2018; 219:1199-1206. [PMID: 29845625 DOI: 10.1111/nph.15222] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 04/04/2018] [Indexed: 05/21/2023]
Abstract
Contents Summary 1199 I. Introduction 1199 II. Selecting beneficial symbionts: one problem, many solutions 1200 III. Control and conflict over legume nodulation 1201 IV. Control and conflict over nodule growth and senescence 1204 V. Conclusion 1204 Acknowledgements 1205 References 1205 SUMMARY: The legume-rhizobia association is a powerful model of the limits of host control over microbes. Legumes regulate the formation of root nodules that house nitrogen-fixing rhizobia and adjust investment into nodule development and growth. However, the range of fitness outcomes in these traits reveals intense conflicts of interest between the partners. New work that we review and synthesize here shows that legumes have evolved varied mechanisms of control over symbionts, but that host control is often subverted by rhizobia. An outcome of this conflict is that both legumes and rhizobia have evolved numerous traits that can improve their own short-term fitness in this interaction, but little evidence exists for any net improvement in the joint trait of nitrogen fixation.
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Affiliation(s)
- Joel L Sachs
- Department of Evolution Ecology & Organismal Biology, University of California, Riverside, CA, 92521, USA
- Department of Botany & Plant Sciences, University of California, Riverside, CA, 92521, USA
- Institute for Integrative Genome Biology, University of California, Riverside, CA, 92521, USA
| | - Kenjiro W Quides
- Department of Evolution Ecology & Organismal Biology, University of California, Riverside, CA, 92521, USA
| | - Camille E Wendlandt
- Department of Botany & Plant Sciences, University of California, Riverside, CA, 92521, USA
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50
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Noë R, Kiers ET. Mycorrhizal Markets, Firms, and Co-ops. Trends Ecol Evol 2018; 33:777-789. [PMID: 30177306 DOI: 10.1016/j.tree.2018.07.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 07/26/2018] [Accepted: 07/31/2018] [Indexed: 12/22/2022]
Abstract
The nutrient exchange mutualism between arbuscular mycorrhizal fungi (AMFs) and their host plants qualifies as a biological market, but several complications have hindered its appropriate use. First, fungal 'trading agents' are hard to identify because AMFs are potentially heterokaryotic, that is, they may contain large numbers of polymorphic nuclei. This means it is difficult to define and study a fungal 'individual' acting as an independent agent with a specific trading strategy. Second, because nutrient exchanges occur via communal structures (arbuscules), this temporarily reduces outbidding competition and transaction costs and hence resembles exchanges among divisions of firms, rather than traditional trade on markets. We discuss how fungal nuclei may coordinate their trading strategies, but nevertheless retain some independence, similar to human co-operatives (co-ops).
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Affiliation(s)
- Ronald Noë
- Department of Psychology, Université de Strasbourg, Strasbourg, France.
| | - E Toby Kiers
- Department of Ecological Science, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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