1
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Riley AB, Grillo MA, Epstein B, Tiffin P, Heath KD. Discordant population structure among rhizobium divided genomes and their legume hosts. Mol Ecol 2023; 32:2646-2659. [PMID: 36161739 DOI: 10.1111/mec.16704] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/15/2022] [Accepted: 09/20/2022] [Indexed: 11/29/2022]
Abstract
Symbiosis often occurs between partners with distinct life history characteristics and dispersal mechanisms. Many bacterial symbionts have genomes comprising multiple replicons with distinct rates of evolution and horizontal transmission. Such differences might drive differences in population structure between hosts and symbionts and among the elements of the divided genomes of bacterial symbionts. These differences might, in turn, shape the evolution of symbiotic interactions and bacterial evolution. Here we use whole genome resequencing of a hierarchically structured sample of 191 strains of Sinorhizobium meliloti collected from 21 locations in southern Europe to characterize population structures of this bacterial symbiont, which forms a root nodule symbiosis with the host plant Medicago truncatula. S. meliloti genomes showed high local (within-site) variation and little isolation by distance. This was particularly true for the two symbiosis elements, pSymA and pSymB, which have population structures that are similar to each other, but distinct from both the bacterial chromosome and the host plant. Given limited recombination on the chromosome, compared to the symbiosis elements, distinct population structures may result from differences in effective gene flow. Alternatively, positive or purifying selection, with little recombination, may explain distinct geographical patterns at the chromosome. Discordant population structure between hosts and symbionts indicates that geographically and genetically distinct host populations in different parts of the range might interact with genetically similar symbionts, potentially minimizing local specialization.
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Affiliation(s)
- Alex B Riley
- Department of Plant Biology, University of Illinois, Urbana, Illinois, USA
| | - Michael A Grillo
- Department of Biology, Loyola University Chicago, Chicago, Illinois, USA
| | - Brendan Epstein
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, USA
| | - Peter Tiffin
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, USA
| | - Katy D Heath
- Department of Plant Biology, University of Illinois, Urbana, Illinois, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois, USA
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2
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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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3
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Yoder JB, Dang A, MacGregor C, Plaza M. Plant‐associate interactions and diversification across trophic levels. Evol Lett 2022; 6:375-389. [PMID: 36254257 PMCID: PMC9554764 DOI: 10.1002/evl3.296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 08/27/2022] [Indexed: 11/11/2022] Open
Abstract
Interactions between species are widely understood to have promoted the diversification of life on Earth, but how interactions spur the formation of new species remains unclear. Interacting species often become locally adapted to each other, but they may also be subject to shared dispersal limitations and environmental conditions. Moreover, theory predicts that different kinds of interactions have different effects on diversification. To better understand how species interactions promote diversification, we compiled population genetic studies of host plants and intimately associated herbivores, parasites, and mutualists. We used Bayesian multiple regressions and the BEDASSLE modeling framework to test whether host and associate population structures were correlated over and above the potentially confounding effects of geography and shared environmental variation. We found that associates' population structure often paralleled their hosts' population structure, and that this effect is robust to accounting for geographic distance and climate. Associate genetic structure was significantly explained by plant genetic structure somewhat more often in antagonistic interactions than in mutualistic ones. This aligns with a key prediction of coevolutionary theory that antagonistic interactions promote diversity through local adaptation of antagonists to hosts, while mutualistic interactions more often promote diversity via the effect of hosts' geographic distribution on mutualists' dispersal.
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Affiliation(s)
- Jeremy B. Yoder
- Department of Biology California State University Northridge Northridge CA 91330 USA
| | - Albert Dang
- Department of Biology California State University Northridge Northridge CA 91330 USA
| | - Caitlin MacGregor
- Department of Biology California State University Northridge Northridge CA 91330 USA
| | - Mikhail Plaza
- Program in Plant Biology and Conservation Northwestern University Evanston IL 60208 USA
- Negaunee Institute for Plant Conservation Science and Action Chicago Botanic Garden Glencoe IL 60035 USA
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4
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Amandine C, Ebert D, Stukenbrock E, Rodríguez de la Vega RC, Tiffin P, Croll D, Tellier A. Unraveling coevolutionary dynamics using ecological genomics. Trends Genet 2022; 38:1003-1012. [PMID: 35715278 DOI: 10.1016/j.tig.2022.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 05/08/2022] [Accepted: 05/10/2022] [Indexed: 11/27/2022]
Abstract
Coevolutionary interactions, from the delicate co-dependency in mutualistic interactions to the antagonistic relationship of hosts and parasites, are a ubiquitous driver of adaptation. Surprisingly, little is known about the genomic processes underlying coevolution in an ecological context. However, species comprise genetically differentiated populations that interact with temporally variable abiotic and biotic environments. We discuss the recent advances in coevolutionary theory and genomics as well as shortcomings, to identify coevolving genes that take into account this spatial and temporal variability of coevolution, and propose a practical guide to understand the dynamic of coevolution using an ecological genomics lens.
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Affiliation(s)
- Cornille Amandine
- Université Paris Saclay, INRAE, CNRS, AgroParisTech, GQE - Le Moulon, 91190 Gif-sur-Yvette, France.
| | - Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
| | - Eva Stukenbrock
- Max Planck Institute for Terrestrial Microbiology, Max Planck Research Group, Fungal Biodiversity, Marburg, Germany
| | | | - Peter Tiffin
- Department of Plant and Microbial Biology, 250 Biological Sciences, 1445 Gortner Ave., University of Minnesota, Saint Paul, MN 55108, USA
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland.
| | - Aurélien Tellier
- Population Genetics, Department of Life Science Systems, Technical University of Munich, Liesel-Beckman-Str. 2, 85354 Freising, Germany.
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5
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Markalanda SH, McFadden CJ, Cassidy ST, Wood CW. The soil microbiome increases plant survival and modifies interactions with root endosymbionts in the field. Ecol Evol 2022; 12:e8283. [PMID: 35126998 PMCID: PMC8796929 DOI: 10.1002/ece3.8283] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 09/20/2021] [Accepted: 09/30/2021] [Indexed: 11/07/2022] Open
Abstract
Evidence is accumulating that the soil microbiome-the community of microorganisms living in soils-has a major effect on plant traits and fitness. However, most work to date has taken place under controlled laboratory conditions and has not experimentally disentangled the effect of the soil microbiome on plant performance from the effects of key endosymbiotic constituents. As a result, it is difficult to extrapolate from existing data to understand the role of the soil microbiome in natural plant populations. To address this gap, we performed a field experiment using the black medick Medicago lupulina to test how the soil microbiome influences plant performance and colonization by two root endosymbionts (the mutualistic nitrogen-fixing bacteria Ensifer spp. and the parasitic root-knot nematode Meloidogyne hapla) under natural conditions. We inoculated all plants with nitrogen-fixing bacteria and factorially manipulated the soil microbiome and nematode infection. We found that plants grown in microbe-depleted soil exhibit greater mortality, but that among the survivors, there was no effect of the soil microbiome on plant performance (shoot biomass, root biomass, or shoot-to-root ratio). The soil microbiome also impacted parasitic nematode infection and affected colonization by mutualistic nitrogen-fixing bacteria in a plant genotype-dependent manner, increasing colonization in some plant genotypes and decreasing it in others. Our results demonstrate the soil microbiome has complex effects on plant-endosymbiont interactions and may be critical for survival under natural conditions.
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Affiliation(s)
| | - Connor J. McFadden
- Department of Biological SciencesUniversity of PittsburghPittsburghPennsylvaniaUSA
| | - Steven T. Cassidy
- Department of Biological SciencesUniversity of PittsburghPittsburghPennsylvaniaUSA
- Present address:
Department of BiologyUniversity of FloridaGainesvilleFloridaUSA
| | - Corlett W. Wood
- Department of Biological SciencesUniversity of PittsburghPittsburghPennsylvaniaUSA
- Present address:
Department of BiologyUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
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6
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Boyle JA, Simonsen AK, Frederickson ME, Stinchcombe JR. Priority effects alter interaction outcomes in a legume-rhizobium mutualism. Proc Biol Sci 2021; 288:20202753. [PMID: 33715440 PMCID: PMC7944086 DOI: 10.1098/rspb.2020.2753] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Priority effects occur when the order of species arrival affects the final community structure. Mutualists often interact with multiple partners in different orders, but if or how priority effects alter interaction outcomes is an open question. In the field, we paired the legume Medicago lupulina with two nodulating strains of Ensifer bacteria that vary in nitrogen-fixing ability. We inoculated plants with strains in different orders and measured interaction outcomes. The first strain to arrive primarily determined plant performance and final relative abundances of rhizobia on roots. Plants that received effective microbes first and ineffective microbes second grew larger than plants inoculated with the same microbes in the opposite order. Our results show that mutualism outcomes can be influenced not just by partner identity, but by the interaction order. Furthermore, hosts receiving high-quality mutualists early can better tolerate low-quality symbionts later, indicating that priority effects may help explain the persistence of ineffective symbionts.
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Affiliation(s)
- Julia A Boyle
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S3B2
| | - Anna K Simonsen
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia.,Department of Biological Sciences, Florida International University, Miami, FL 33199, USA
| | - Megan E Frederickson
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S3B2
| | - John R Stinchcombe
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S3B2.,Koffler Scientific Reserve, University of Toronto, Toronto, Ontario, Canada M5S3B2
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7
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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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8
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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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9
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Stoy KS, Gibson AK, Gerardo NM, Morran LT. A need to consider the evolutionary genetics of host-symbiont mutualisms. J Evol Biol 2020; 33:1656-1668. [PMID: 33047414 DOI: 10.1111/jeb.13715] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 09/20/2020] [Accepted: 09/27/2020] [Indexed: 12/28/2022]
Abstract
Despite the ubiquity and importance of mutualistic interactions, we know little about the evolutionary genetics underlying their long-term persistence. As in antagonistic interactions, mutualistic symbioses are characterized by substantial levels of phenotypic and genetic diversity. In contrast to antagonistic interactions, however, we, by and large, do not understand how this variation arises, how it is maintained, nor its implications for future evolutionary change. Currently, we rely on phenotypic models to address the persistence of mutualistic symbioses, but the success of an interaction almost certainly depends heavily on genetic interactions. In this review, we argue that evolutionary genetic models could provide a framework for understanding the causes and consequences of diversity and why selection may favour processes that maintain variation in mutualistic interactions.
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Affiliation(s)
- Kayla S Stoy
- Department of Biology, Emory University, Atlanta, GA, USA.,Population Biology, Ecology, and Evolution Program, Division of Biological and Biomedical Sciences, Emory University, Atlanta, GA, USA
| | - Amanda K Gibson
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | | | - Levi T Morran
- Department of Biology, Emory University, Atlanta, GA, USA
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10
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Brown SP, Grillo MA, Podowski JC, Heath KD. Soil origin and plant genotype structure distinct microbiome compartments in the model legume Medicago truncatula. MICROBIOME 2020; 8:139. [PMID: 32988416 PMCID: PMC7523075 DOI: 10.1186/s40168-020-00915-9] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 09/01/2020] [Indexed: 05/20/2023]
Abstract
BACKGROUND Understanding the genetic and environmental factors that structure plant microbiomes is necessary for leveraging these interactions to address critical needs in agriculture, conservation, and sustainability. Legumes, which form root nodule symbioses with nitrogen-fixing rhizobia, have served as model plants for understanding the genetics and evolution of beneficial plant-microbe interactions for decades, and thus have added value as models of plant-microbiome interactions. Here we use a common garden experiment with 16S rRNA gene amplicon and shotgun metagenomic sequencing to study the drivers of microbiome diversity and composition in three genotypes of the model legume Medicago truncatula grown in two native soil communities. RESULTS Bacterial diversity decreased between external (rhizosphere) and internal plant compartments (root endosphere, nodule endosphere, and leaf endosphere). Community composition was shaped by strong compartment × soil origin and compartment × plant genotype interactions, driven by significant soil origin effects in the rhizosphere and significant plant genotype effects in the root endosphere. Nevertheless, all compartments were dominated by Ensifer, the genus of rhizobia that forms root nodule symbiosis with M. truncatula, and additional shotgun metagenomic sequencing suggests that the nodulating Ensifer were not genetically distinguishable from those elsewhere in the plant. We also identify a handful of OTUs that are common in nodule tissues, which are likely colonized from the root endosphere. CONCLUSIONS Our results demonstrate strong host filtering effects, with rhizospheres driven by soil origin and internal plant compartments driven by host genetics, and identify several key nodule-inhabiting taxa that coexist with rhizobia in the native range. Our results set the stage for future functional genetic experiments aimed at expanding our pairwise understanding of legume-rhizobium symbiosis toward a more mechanistic understanding of plant microbiomes. Video Abstract.
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Affiliation(s)
- Shawn P. Brown
- Department of Plant Biology, University of Illinois, 505 S. Goodwin Ave, Urbana, IL 61801 USA
- Department of Biological Sciences, The University of Memphis, 3774 Walker Ave, Memphis, TN 38152 USA
- Center for Biodiversity Research, The University of Memphis, 3774 Walker Ave, Memphis, TN 38152 USA
| | - Michael A. Grillo
- Department of Plant Biology, University of Illinois, 505 S. Goodwin Ave, Urbana, IL 61801 USA
- Department of Biology, Loyola University Chicago, 1032 W. Sheridan Rd, Chicago, IL 60618 USA
| | - Justin C. Podowski
- Department of Plant Biology, University of Illinois, 505 S. Goodwin Ave, Urbana, IL 61801 USA
- Department of Geophysical Sciences, University of Chicago, 5734 S Ellis Ave, Chicago, IL 60637 USA
| | - Katy D. Heath
- Department of Plant Biology, University of Illinois, 505 S. Goodwin Ave, Urbana, IL 61801 USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois, 1206 W. Gregory Dr, Urbana, IL 61801 USA
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11
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Batstone RT, Peters MAE, Simonsen AK, Stinchcombe JR, Frederickson ME. Environmental variation impacts trait expression and selection in the legume-rhizobium symbiosis. AMERICAN JOURNAL OF BOTANY 2020; 107:195-208. [PMID: 32064599 DOI: 10.1002/ajb2.1432] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 11/04/2019] [Indexed: 05/22/2023]
Abstract
PREMISE The ecological outcomes of mutualism are well known to shift across abiotic or biotic environments, but few studies have addressed how different environments impact evolutionary responses, including the intensity of selection on and the expression of genetic variance in key mutualism-related traits. METHODS We planted 30 maternal lines of the legume Medicago lupulina in four field common gardens and compared our measures of selection on and genetic variance in nodulation, a key trait reflecting legume investment in the symbiosis, with those from a previous greenhouse experiment using the same 30 M. lupulina lines. RESULTS We found that both the mean and genetic variance for nodulation were much greater in the greenhouse than in the field and that the form of selection on nodulation significantly differed across environments. We also found significant genotype-by-environment (G × E) effects for fitness-related traits that were generated by differences in the rank order of plant lines among environments. CONCLUSIONS Overall, our results suggest that the expression of genotypic variation and selection on nodulation differ across environments. In the field, significant rank-order changes for plant fitness potentially help maintain genetic variation in natural populations, even in the face of directional or stabilizing selection.
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Affiliation(s)
- Rebecca T Batstone
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
- Carl Woese Institute for Genomic Biology, University of Illinois at Champaign-Urbana, Urbana, IL, 61801, USA
| | - Madeline A E Peters
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Anna K Simonsen
- Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
| | - John R Stinchcombe
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
- Koffler Scientific Reserve, University of Toronto, King, ON, L7B 1K5, Canada
| | - Megan E Frederickson
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
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12
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Bamba M, Aoki S, Kajita T, Setoguchi H, Watano Y, Sato S, Tsuchimatsu T. Exploring Genetic Diversity and Signatures of Horizontal Gene Transfer in Nodule Bacteria Associated with Lotus japonicus in Natural Environments. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:1110-1120. [PMID: 30880586 DOI: 10.1094/mpmi-02-19-0039-r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
To investigate the genetic diversity and understand the process of horizontal gene transfer (HGT) in nodule bacteria associated with Lotus japonicus, we analyzed sequences of three housekeeping and five symbiotic genes using samples from a geographically wide range in Japan. A phylogenetic analysis of the housekeeping genes indicated that L. japonicus in natural environments was associated with diverse lineages of Mesorhizobium spp., whereas the sequences of symbiotic genes were highly similar between strains, resulting in remarkably low nucleotide diversity at both synonymous and nonsynonymous sites. Guanine-cytosine content values were lower in symbiotic genes, and relative frequencies of recombination between symbiotic genes were also lower than those between housekeeping genes. An analysis of molecular variance showed significant genetic differentiation among populations in both symbiotic and housekeeping genes. These results confirm that the Mesorhizobium genes required for symbiosis with L. japonicus behave as a genomic island (i.e., a symbiosis island) and suggest that this island has spread into diverse genomic backgrounds of Mesorhizobium via HGT events in natural environments. Furthermore, our data compilation revealed that the genetic diversity of symbiotic genes in L. japonicus-associated symbionts was among the lowest compared with reports of other species, which may be related to the recent population expansion proposed in Japanese populations of L. japonicus.
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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
| | - 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 Ryukyus, 870 Uehara, Taketomi-cho, Yaeyama-gun, Okinawa 907-1541, Japan
| | - Hiroaki Setoguchi
- Graduate School of Human and Environmental Studies, Kyoto University, Yoshidanihonmatsu-cho, Sakyo-ku, Kyoto 606-8501 Japan
| | - Yasuyuki Watano
- Department of Biology, Graduate School of Science, Chiba University
| | - Shusei Sato
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
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13
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Ji Z, Liu T, Zhang J, Yan H, Wang E, Cui Q, Chen W, Chen W. Genetic divergence among Bradyrhizobium strains nodulating wild and cultivated Kummerowia spp. in China. Syst Appl Microbiol 2018; 42:223-231. [PMID: 30343835 DOI: 10.1016/j.syapm.2018.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 10/07/2018] [Accepted: 10/09/2018] [Indexed: 11/29/2022]
Abstract
Distribution of rhizobial species is affected by geographical isolation and selected by leguminous hosts, however, little is known about the molecular evolution of rhizobia nodulating the same legume in different eco-environments. In present study, the microevolution of Bradyrhizobium associated with the leguminous grass Kummerowia grown in exurban areas and cultivated in urban areas in China was investigated. Total 14 genospecies, including seven new groups, were identified based on a concatenated sequence analysis of taxonomic markers (SMc00019, truA and thrA) for 94 representative strains. Results demonstrated that lower levels of nucleotide diversity were found in the strains isolated from urban areas compared with those isolated from exurban areas, based on the evolutional analyses of three housekeeping genes (atpD, glnII and recA), two symbiosis-related genes (nodC and nifH), and the taxonomic markers. Moreover, compared with urban areas, gene exchange and recombination occurred more frequently among the genospecies isolated from exurban areas, regardless of the geographical distribution. Finally, the evolutionary lineage of Bradyrhizobium strains isolated from urban areas was independent of that of the strains isolated from exurban areas. In summary, the evolutionary history of Kummerowia bradyrhizobia may have been gradually segregated to different evolutionary lineages, irrespective of distinct biogeography.
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Affiliation(s)
- Zhaojun Ji
- College of Life Science and Horqin Plant Stress Biology Research Institute, Inner Mongolia University for the Nationalities, Tongliao 028042, Inner Mongolia, China; State Key Laboratory of Agrobiotechnology, Beijing 100193, China; College of Biological Sciences and Rhizobium Research Center, China Agricultural University, Beijing 100193, China
| | - Tianyan Liu
- State Key Laboratory of Agrobiotechnology, Beijing 100193, China; College of Biological Sciences and Rhizobium Research Center, China Agricultural University, Beijing 100193, China
| | - Jixing Zhang
- College of Life Science and Horqin Plant Stress Biology Research Institute, Inner Mongolia University for the Nationalities, Tongliao 028042, Inner Mongolia, China
| | - Hui Yan
- State Key Laboratory of Agrobiotechnology, Beijing 100193, China; College of Biological Sciences and Rhizobium Research Center, China Agricultural University, Beijing 100193, China
| | - Entao Wang
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, México D. F. 11340, México
| | - Qingguo Cui
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Wenxin Chen
- State Key Laboratory of Agrobiotechnology, Beijing 100193, China; College of Biological Sciences and Rhizobium Research Center, China Agricultural University, Beijing 100193, China
| | - Wenfeng Chen
- State Key Laboratory of Agrobiotechnology, Beijing 100193, China; College of Biological Sciences and Rhizobium Research Center, China Agricultural University, Beijing 100193, China.
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14
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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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15
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Wood CW, Pilkington BL, Vaidya P, Biel C, Stinchcombe JR. Genetic conflict with a parasitic nematode disrupts the legume-rhizobia mutualism. Evol Lett 2018; 2:233-245. [PMID: 30283679 PMCID: PMC6121810 DOI: 10.1002/evl3.51] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 02/07/2018] [Accepted: 03/09/2018] [Indexed: 12/13/2022] Open
Abstract
Genetic variation for partner quality in mutualisms is an evolutionary paradox. One possible resolution to this puzzle is that there is a tradeoff between partner quality and other fitness‐related traits. Here, we tested whether susceptibility to parasitism is one such tradeoff in the mutualism between legumes and nitrogen‐fixing bacteria (rhizobia). We performed two greenhouse experiments with the legume Medicago truncatula. In the first, we inoculated each plant with the rhizobia Ensifer meliloti and with one of 40 genotypes of the parasitic root‐knot nematode Meloidogyne hapla. In the second experiment, we inoculated all plants with rhizobia and half of the plants with a genetically variable population of nematodes. Using the number of nematode galls as a proxy for infection severity, we found that plant genotypes differed in susceptibility to nematode infection, and nematode genotypes differed in infectivity. Second, we showed that there was a genetic correlation between the number of mutualistic structures formed by rhizobia (nodules) and the number of parasitic structures formed by nematodes (galls). Finally, we found that nematodes disrupt the rhizobia mutualism: nematode‐infected plants formed fewer nodules and had less nodule biomass than uninfected plants. Our results demonstrate that there is genetic conflict between attracting rhizobia and repelling nematodes in Medicago. If genetic conflict with parasitism is a general feature of mutualism, it could account for the maintenance of genetic variation in partner quality and influence the evolutionary dynamics of positive species interactions.
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Affiliation(s)
- Corlett W Wood
- Department of Ecology and Evolutionary Biology University of Toronto Toronto Ontario M5S3B2 Canada
| | - Bonnie L Pilkington
- Department of Ecology and Evolutionary Biology University of Toronto Toronto Ontario M5S3B2 Canada
| | - Priya Vaidya
- Department of Ecology and Evolutionary Biology University of Toronto Toronto Ontario M5S3B2 Canada
| | - Caroline Biel
- Department of Ecology and Evolutionary Biology University of Toronto Toronto Ontario M5S3B2 Canada
| | - John R Stinchcombe
- Department of Ecology and Evolutionary Biology University of Toronto Toronto Ontario M5S3B2 Canada.,Koffler Scientific Reserve University of Toronto Toronto Ontario M5S3B2 Canada
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16
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Porter SS, Faber-Hammond JJ, Friesen ML. Co-invading symbiotic mutualists of Medicago polymorpha retain high ancestral diversity and contain diverse accessory genomes. FEMS Microbiol Ecol 2017; 94:4705886. [DOI: 10.1093/femsec/fix168] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 11/29/2017] [Indexed: 02/06/2023] Open
Affiliation(s)
- Stephanie S Porter
- School of Biological Sciences, Washington State University, 14204 NE Salmon Creek Ave, Vancouver, WA 98686, USA
| | - Joshua J Faber-Hammond
- School of Biological Sciences, Washington State University, 14204 NE Salmon Creek Ave, Vancouver, WA 98686, USA
| | - Maren L Friesen
- Department of Plant Biology, Michigan State University, 612 Wilson Road, East Lansing, MI, 48824, USA
- Department of Plant Pathology, Washington State University, P.O. Box 646430 Pullman, WA 99164, USA
- Department of Crop and Soil Sciences, Washington State University, P.O. Box 646420 Pullman, WA 99164, USA
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17
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Harrison TL, Wood CW, Borges IL, Stinchcombe JR. No evidence for adaptation to local rhizobial mutualists in the legume Medicago lupulina. Ecol Evol 2017; 7:4367-4376. [PMID: 28649348 PMCID: PMC5478075 DOI: 10.1002/ece3.3012] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 03/15/2017] [Accepted: 03/27/2017] [Indexed: 12/31/2022] Open
Abstract
Local adaptation is a common but not ubiquitous feature of species interactions, and understanding the circumstances under which it evolves illuminates the factors that influence adaptive population divergence. Antagonistic species interactions dominate the local adaptation literature relative to mutualistic ones, preventing an overall assessment of adaptation within interspecific interactions. Here, we tested whether the legume Medicago lupulina is adapted to the locally abundant species of mutualistic nitrogen-fixing rhizobial bacteria that vary in frequency across its eastern North American range. We reciprocally inoculated northern and southern M. lupulina genotypes with the northern (Ensifer medicae) or southern bacterium (E. meliloti) in a greenhouse experiment. Despite producing different numbers of root nodules (the structures in which the plants house the bacteria), neither northern nor southern plants produced more seeds, flowered earlier, or were more likely to flower when inoculated with their local rhizobia. We then used a pre-existing dataset to perform a genome scan for loci that showed elevated differentiation between field-collected plants that hosted different bacteria. None of the loci we identified belonged to the well-characterized suite of legume-rhizobia symbiosis genes, suggesting that the rhizobia do not drive genetic divergence between M. lupulina populations. Our results demonstrate that symbiont local adaptation has not evolved in this mutualism despite large-scale geographic variation in the identity of the interacting species.
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Affiliation(s)
- Tia L. Harrison
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
| | - Corlett W. Wood
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
| | - Isabela L. Borges
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
| | - John R. Stinchcombe
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
- Centre for Genome Evolution and FunctionUniversity of TorontoTorontoONCanada
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