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Sarrette B, Luu TB, Johansson A, Fliegmann J, Pouzet C, Pichereaux C, Remblière C, Sauviac L, Carles N, Amblard E, Guyot V, Bonhomme M, Cullimore J, Gough C, Jacquet C, Pauly N. Medicago truncatula SOBIR1 controls pathogen immunity and specificity in the Rhizobium-legume symbiosis. PLANT, CELL & ENVIRONMENT 2024. [PMID: 39225339 DOI: 10.1111/pce.15071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 05/16/2024] [Accepted: 07/21/2024] [Indexed: 09/04/2024]
Abstract
Medicago truncatula Nod Factor Perception (MtNFP) plays a role in both the Rhizobium-Legume (RL) symbiosis and plant immunity, and evidence suggests that the immune-related function of MtNFP is relevant for symbiosis. To better understand these roles of MtNFP, we sought to identify new interacting partners. We screened a yeast-2-hybrid cDNA library from Aphanomyces euteiches infected and noninfected M. truncatula roots. The M. truncatula leucine-rich repeat (LRR) receptor-like kinase SUPPRESSOR OF BIR1 (MtSOBIR1) was identified as an interactor of MtNFP and was characterised for kinase activity, and potential roles in symbiosis and plant immunity. We showed that the kinase domain of MtSOBIR1 is active and can transphosphorylate the pseudo-kinase domain of MtNFP. MtSOBIR1 could functionally complement Atsobir1 and Nbsobir1/sobir1-like mutants for defence activation, and Mtsobir1 mutants were defective in immune responses to A. euteiches. For symbiosis, we showed that Mtsobir1 mutant plants had both a strong, early infection defect and defects in the defence suppression in nodules, and both effects were plant genotype- and rhizobial strain-specific. This work highlights a conserved function for MtSOBIR1 in activating defence responses to pathogen attack, and potentially novel symbiotic functions of downregulating defence in association with the control of symbiotic specificity.
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Affiliation(s)
- Baptiste Sarrette
- Laboratory of Plant-Microbe Interactions and Environment (LIPME), University Toulouse III, INRAE, CNRS, Castanet-Tolosan Cedex, France
| | - Thi-Bich Luu
- Laboratory of Plant-Microbe Interactions and Environment (LIPME), University Toulouse III, INRAE, CNRS, Castanet-Tolosan Cedex, France
| | - Alexander Johansson
- Laboratory of Plant-Microbe Interactions and Environment (LIPME), University Toulouse III, INRAE, CNRS, Castanet-Tolosan Cedex, France
| | - Judith Fliegmann
- Centre for Plant Molecular Biology (ZMBP) - Plant Biochemistry, University of Tübingen, Tübingen, Germany
| | - Cécile Pouzet
- Fédération de Recherche Agrobiosciences, Interactions and Biodiversity Research (FR AIB) Imaging and Proteomics platforms, University of Toulouse III, CNRS, Auzeville-Tolosan, France
| | - Carole Pichereaux
- Fédération de Recherche Agrobiosciences, Interactions and Biodiversity Research (FR AIB) Imaging and Proteomics platforms, University of Toulouse III, CNRS, Auzeville-Tolosan, France
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
- Infrastructure Nationale de Protéomique, ProFI, Toulouse, France
| | - Céline Remblière
- Laboratory of Plant-Microbe Interactions and Environment (LIPME), University Toulouse III, INRAE, CNRS, Castanet-Tolosan Cedex, France
| | - Laurent Sauviac
- Laboratory of Plant-Microbe Interactions and Environment (LIPME), University Toulouse III, INRAE, CNRS, Castanet-Tolosan Cedex, France
| | - Noémie Carles
- Laboratory of Plant-Microbe Interactions and Environment (LIPME), University Toulouse III, INRAE, CNRS, Castanet-Tolosan Cedex, France
| | - Emilie Amblard
- Laboratoire de Recherche en Sciences Végétales, University of Toulouse, CNRS, UPS, Castanet-Tolosan, France
| | - Valentin Guyot
- Laboratory of Plant-Microbe Interactions and Environment (LIPME), University Toulouse III, INRAE, CNRS, Castanet-Tolosan Cedex, France
| | - Maxime Bonhomme
- Laboratoire de Recherche en Sciences Végétales, University of Toulouse, CNRS, UPS, Castanet-Tolosan, France
| | - Julie Cullimore
- Laboratory of Plant-Microbe Interactions and Environment (LIPME), University Toulouse III, INRAE, CNRS, Castanet-Tolosan Cedex, France
| | - Clare Gough
- Laboratory of Plant-Microbe Interactions and Environment (LIPME), University Toulouse III, INRAE, CNRS, Castanet-Tolosan Cedex, France
| | - Christophe Jacquet
- Laboratoire de Recherche en Sciences Végétales, University of Toulouse, CNRS, UPS, Castanet-Tolosan, France
| | - Nicolas Pauly
- Laboratory of Plant-Microbe Interactions and Environment (LIPME), University Toulouse III, INRAE, CNRS, Castanet-Tolosan Cedex, France
- Institut Sophia Agrobiotech, Université Côte d'Azur, INRAE, CNRS, Sophia Antipolis Cedex, France
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Vaccaro F, Passeri I, Ajijah N, Bettini P, Courty PE, Dębiec-Andrzejewska K, Joshi N, Kowalewska Ł, Stasiuk R, Musiałowski M, Pranaw K, Mengoni A. Genotype-by-genotype interkingdom cross-talk between symbiotic nitrogen fixing Sinorhizobium meliloti strains and Trichoderma species. Microbiol Res 2024; 285:127768. [PMID: 38820702 DOI: 10.1016/j.micres.2024.127768] [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: 02/08/2024] [Revised: 05/10/2024] [Accepted: 05/13/2024] [Indexed: 06/02/2024]
Abstract
In the understanding of the molecular interaction between plants and their microbiome, a key point is to identify simplified models of the microbiome including relevant bacterial and fungal partners which could also be effective in plant growth promotion. Here, as proof-of-concept, we aim to identify the possible molecular interactions between symbiotic nitrogen-fixing rhizobia and soil fungi (Trichoderma spp.), hence shed light on synergistic roles rhizospheric fungi could have in the biology of symbiotic nitrogen fixation bacteria. We selected 4 strains of the model rhizobium Sinorhizobium meliloti and 4 Trichoderma species (T. velutinum, T. tomentosum, T. gamsii and T. harzianum). In an experimental scheme of 4 ×4 strains x species combinations, we investigated the rhizobia physiological and transcriptomic responses elicited by fungal spent media, as well as spent media effects on rhizobia-host legume plant (alfalfa, Medicago sativa L.) symbiosis. Fungal spent media had large effects on rhizobia, specific for each fungal species and rhizobial strains combination, indicating a generalized rhizobia genotype x fungal genotype interaction, including synergistic, neutral and antagonistic effects on alfalfa symbiotic phenotypes. Differential expression of a high number of genes was shown in rhizobia strains with up to 25% of total genes differentially expressed upon treatment of cultures with fungal spent media. Percentages over total genes and type of genes differentially expressed changed according to both fungal species and rhizobial strain. To support the hypothesis of a relevant rhizobia genotype x fungal genotype interaction, a nested Likelihood Ratio Test indicated that the model considering the fungus-rhizobium interaction explained 23.4% of differentially expressed genes. Our results provide insights into molecular interactions involving nitrogen-fixing rhizobia and rhizospheric fungi, highlighting the panoply of genes and genotypic interactions (fungus, rhizobium, host plant) which may concur to plant symbiosis.
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Affiliation(s)
| | | | - Nur Ajijah
- Department of Environmental Microbiology and Biotechnology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Poland
| | | | | | | | - Namrata Joshi
- Department of Environmental Microbiology and Biotechnology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Poland
| | - Łucja Kowalewska
- Department of Plant Anatomy and Cytology, Institute of Plant Experimental Biology and Biotechnology, Faculty of Biology, University of Warsaw, Poland
| | - Robert Stasiuk
- Department of Geomicrobiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Poland
| | - Marcin Musiałowski
- Department of Geomicrobiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Poland
| | - Kumar Pranaw
- Department of Environmental Microbiology and Biotechnology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Poland; School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India
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Cao K, Chen J, Li Q, Gu P, Li L, Huang R. Bacteria from nodules of Abrus mollis Hance: genetic diversity and screening of highly efficient growth-promoting strains. Front Microbiol 2024; 15:1345000. [PMID: 38680912 PMCID: PMC11045970 DOI: 10.3389/fmicb.2024.1345000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 03/21/2024] [Indexed: 05/01/2024] Open
Abstract
Introduction Abrus mollis Hance. (AM) is an important species used in southern Chinese medicine. It is mainly found in Guangdong and Guangxi provinces in China, and it is effective in the treatment of hepatitis. Endophytic bacteria are known to affect the growth and quality of medicinal plants. However, there are limited reports describing endophytic bacteria related to AM. Methods In the present study, Illumina-based 16S rRNA gene sequencing was used to investigate the endophytic bacterial communities of root nodules of AM at five sampling sites in Guangxi. In addition, 179 strains of endophytic bacteria were isolated and categorized into 13 haplotypes based on recA sequence analysis. Results The phylogeny of the 16S rRNA gene sequences revealed a predominance of nonrhizobial endophytes. Microbial diversity analysis showed that Proteobacteria was the dominant phylum in all samples, while Bradyrhizobium was the dominant genus in different samples. An efficient strain, Rhizobium tropici FM-19, was screened and obtained through greenhouse experiments. The AM plants inoculated with this strain showed the best growth performance and high nitrogen fixation and nodulation capacity. Notably, total phenols and total flavonoids, important active components in AM, increased by 30.9 and 42.7%, respectively, after inoculation with Rhizobium tropici FM-19. Discussion This study provides insights into the complex microbial diversity of AM nodules and provides strain information for the efficient cultivation of AM.
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Affiliation(s)
- Kexin Cao
- College of Agriculture, Guangxi University, Nanning, Guangxi, China
| | - Jianhua Chen
- College of Pharmacy, Guangxi University of Chinese Medicine, Nanning, Guangxi, China
| | - Qiuling Li
- College of Pharmacy, Guangxi University of Chinese Medicine, Nanning, Guangxi, China
| | - Peng Gu
- College of Pharmacy, Guangxi University of Chinese Medicine, Nanning, Guangxi, China
| | - Liangbo Li
- College of Pharmacy, Guangxi University of Chinese Medicine, Nanning, Guangxi, China
| | - Rongshao Huang
- College of Agriculture, Guangxi University, Nanning, Guangxi, China
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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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Nandety RS, Wen J, Mysore KS. Medicago truncatula resources to study legume biology and symbiotic nitrogen fixation. FUNDAMENTAL RESEARCH 2023; 3:219-224. [PMID: 38932916 PMCID: PMC11197554 DOI: 10.1016/j.fmre.2022.06.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 06/01/2022] [Accepted: 06/19/2022] [Indexed: 10/17/2022] Open
Abstract
Medicago truncatula is a chosen model for legumes towards deciphering fundamental legume biology, especially symbiotic nitrogen fixation. Current genomic resources for M. truncatula include a completed whole genome sequence information for R108 and Jemalong A17 accessions along with the sparse draft genome sequences for other 226 M. truncatula accessions. These genomic resources are complemented by the availability of mutant resources such as retrotransposon (Tnt1) insertion mutants in R108 and fast neutron bombardment (FNB) mutants in A17. In addition, several M. truncatula databases such as small secreted peptides (SSPs) database, transporter protein database, gene expression atlas, proteomic atlas, and metabolite atlas are available to the research community. This review describes these resources and provide information regarding how to access these resources.
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Affiliation(s)
- Raja Sekhar Nandety
- Institute for Agricultural Biosciences, Oklahoma State University, 3210 Sam Noble Parkway, Ardmore, OK 73401, United States
- USDA-ARS, Cereal Crops Research Unit, Edward T. Schafer Agricultural Research Center, Fargo, ND 58102, United States
| | - Jiangqi Wen
- Institute for Agricultural Biosciences, Oklahoma State University, 3210 Sam Noble Parkway, Ardmore, OK 73401, United States
| | - Kirankumar S. Mysore
- Institute for Agricultural Biosciences, Oklahoma State University, 3210 Sam Noble Parkway, Ardmore, OK 73401, United States
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, United States
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6
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Jardinaud MF, Carrere S, Gourion B, Gamas P. Symbiotic Nodule Development and Efficiency in the Medicago truncatula Mtefd-1 Mutant Is Highly Dependent on Sinorhizobium Strains. PLANT & CELL PHYSIOLOGY 2023; 64:27-42. [PMID: 36151948 DOI: 10.1093/pcp/pcac134] [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: 06/30/2022] [Revised: 09/22/2022] [Accepted: 09/23/2022] [Indexed: 06/16/2023]
Abstract
Symbiotic nitrogen fixation (SNF) can play a key role in agroecosystems to reduce the negative impact of nitrogen fertilizers. Its efficiency is strongly affected by the combination of bacterial and plant genotypes, but the mechanisms responsible for the differences in the efficiency of rhizobium strains are not well documented. In Medicago truncatula, SNF has been mostly studied using model systems, such as M. truncatula A17 in interaction with Sinorhizobium meliloti Sm2011. Here we analyzed both the wild-type (wt) A17 and the Mtefd-1 mutant in interaction with five S. meliloti and two Sinorhizobium medicae strains. ETHYLENE RESPONSE FACTOR REQUIRED FOR NODULE DIFFERENTIATION (MtEFD) encodes a transcription factor, which contributes to the control of nodule number and differentiation in M. truncatula. We found that, in contrast to Sm2011, four strains induce functional (Fix+) nodules in Mtefd-1, although less efficient for SNF than in wt A17. In contrast, the Mtefd-1 hypernodulation phenotype is not strain-dependent. We compared the plant nodule transcriptomes in response to SmBL225C, a highly efficient strain with A17, versus Sm2011, in wt and Mtefd-1 backgrounds. This revealed faster nodule development with SmBL225C and early nodule senescence with Sm2011. These RNA sequencing analyses allowed us to identify candidate plant factors that could drive the differential nodule phenotype. In conclusion, this work shows the value of having a set of rhizobium strains to fully evaluate the biological importance of a plant symbiotic gene.
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Affiliation(s)
- Marie-Françoise Jardinaud
- LIPME, INRAE, CNRS, Université de Toulouse, 24 Chemin de Borde Rouge, Auzeville-Tolosane 31320, France
| | - Sebastien Carrere
- LIPME, INRAE, CNRS, Université de Toulouse, 24 Chemin de Borde Rouge, Auzeville-Tolosane 31320, France
| | - Benjamin Gourion
- LIPME, INRAE, CNRS, Université de Toulouse, 24 Chemin de Borde Rouge, Auzeville-Tolosane 31320, France
| | - Pascal Gamas
- LIPME, INRAE, CNRS, Université de Toulouse, 24 Chemin de Borde Rouge, Auzeville-Tolosane 31320, France
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7
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Genome-Wide Association Studies across Environmental and Genetic Contexts Reveal Complex Genetic Architecture of Symbiotic Extended Phenotypes. mBio 2022; 13:e0182322. [PMID: 36286519 PMCID: PMC9765617 DOI: 10.1128/mbio.01823-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A goal of modern biology is to develop the genotype-phenotype (G→P) map, a predictive understanding of how genomic information generates trait variation that forms the basis of both natural and managed communities. As microbiome research advances, however, it has become clear that many of these traits are symbiotic extended phenotypes, being governed by genetic variation encoded not only by the host's own genome, but also by the genomes of myriad cryptic symbionts. Building a reliable G→P map therefore requires accounting for the multitude of interacting genes and even genomes involved in symbiosis. Here, we use naturally occurring genetic variation in 191 strains of the model microbial symbiont Sinorhizobium meliloti paired with two genotypes of the host Medicago truncatula in four genome-wide association studies (GWAS) to determine the genomic architecture of a key symbiotic extended phenotype-partner quality, or the fitness benefit conferred to a host by a particular symbiont genotype, within and across environmental contexts and host genotypes. We define three novel categories of loci in rhizobium genomes that must be accounted for if we want to build a reliable G→P map of partner quality; namely, (i) loci whose identities depend on the environment, (ii) those that depend on the host genotype with which rhizobia interact, and (iii) universal loci that are likely important in all or most environments. IMPORTANCE Given the rapid rise of research on how microbiomes can be harnessed to improve host health, understanding the contribution of microbial genetic variation to host phenotypic variation is pressing, and will better enable us to predict the evolution of (and select more precisely for) symbiotic extended phenotypes that impact host health. We uncover extensive context-dependency in both the identity and functions of symbiont loci that control host growth, which makes predicting the genes and pathways important for determining symbiotic outcomes under different conditions more challenging. Despite this context-dependency, we also resolve a core set of universal loci that are likely important in all or most environments, and thus, serve as excellent targets both for genetic engineering and future coevolutionary studies of symbiosis.
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8
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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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9
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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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10
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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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11
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Batstone RT. Genomes within genomes: nested symbiosis and its implications for plant evolution. THE NEW PHYTOLOGIST 2022; 234:28-34. [PMID: 34761378 DOI: 10.1111/nph.17847] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Accepted: 10/20/2021] [Indexed: 06/13/2023]
Abstract
Many important plant traits are products of nested symbiosis: mobile genetic elements (MGEs) are nested within microbes, which in turn, are nested within plants. Plant trait variation is therefore not only determined by the plant's genome, but also by loci within microbes and MGEs. Yet it remains unclear how interactions and coevolution within nested symbiosis impacts the evolution of plant traits. Despite the complexities of nested symbiosis, including nonadditive interactions, understanding the evolution of plant traits is facilitated by combining quantitative genetic and functional genomic approaches that explicitly consider sources of nested genetic variation (from loci in MGEs to microbiomes). Additionally, understanding coevolution within nested symbiosis enables us to design or select for MGEs that promote plant health.
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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
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12
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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; 23:3358. [PMID: 35328782 PMCID: PMC8954435 DOI: 10.3390/ijms23063358] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [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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Affiliation(s)
- Lisa Cangioli
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy
| | - Francesca Vaccaro
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy
| | - Margherita Fini
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy
| | - Alessio Mengoni
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy
| | - Camilla Fagorzi
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy
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13
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Safdari P, Höckerstedt L, Brosche M, Salojärvi J, Laine AL. Genotype-Specific Expression and NLR Repertoire Contribute to Phenotypic Resistance Diversity in Plantago lanceolata. FRONTIERS IN PLANT SCIENCE 2021; 12:675760. [PMID: 34322142 PMCID: PMC8311189 DOI: 10.3389/fpls.2021.675760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 06/14/2021] [Indexed: 06/13/2023]
Abstract
High levels of phenotypic variation in resistance appears to be nearly ubiquitous across natural host populations. Molecular processes contributing to this variation in nature are still poorly known, although theory predicts resistance to evolve at specific loci driven by pathogen-imposed selection. Nucleotide-binding leucine-rich repeat (NLR) genes play an important role in pathogen recognition, downstream defense responses and defense signaling. Identifying the natural variation in NLRs has the potential to increase our understanding of how NLR diversity is generated and maintained, and how to manage disease resistance. Here, we sequenced the transcriptomes of five different Plantago lanceolata genotypes when inoculated by the same strain of obligate fungal pathogen Podosphaera plantaginis. A de novo transcriptome assembly of RNA-sequencing data yielded 24,332 gene models with N50 value of 1,329 base pairs and gene space completeness of 66.5%. The gene expression data showed highly varying responses where each plant genotype demonstrated a unique expression profile in response to the pathogen, regardless of the resistance phenotype. Analysis on the conserved NB-ARC domain demonstrated a diverse NLR repertoire in P. lanceolata consistent with the high phenotypic resistance diversity in this species. We find evidence of selection generating diversity at some of the NLR loci. Jointly, our results demonstrate that phenotypic resistance diversity results from a crosstalk between different defense mechanisms. In conclusion, characterizing the architecture of resistance in natural host populations may shed unprecedented light on the potential of evolution to generate variation.
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Affiliation(s)
- Pezhman Safdari
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki, Finland
| | - Layla Höckerstedt
- Climate System Research, Finnish Meteorological Institute, Helsinki, Finland
| | - Mikael Brosche
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki, Finland
| | - Jarkko Salojärvi
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki, Finland
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Anna-Liisa Laine
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki, Finland
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
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14
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Gourion B, Ratet P. Avoidance of detrimental defense responses in beneficial plant-microbe interactions. Curr Opin Biotechnol 2021; 70:266-272. [PMID: 34252756 DOI: 10.1016/j.copbio.2021.06.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 06/07/2021] [Accepted: 06/15/2021] [Indexed: 12/21/2022]
Abstract
In the environment microbes interact with plants and provide them with benefits that include protection against biotic and abiotic stresses as well as improved nutrition. However, plants are also exposed to parasites and pathogens. To manage appropriate responses, evolution has resulted in improved tolerance of plants to beneficial microbes while keeping the ability to recognize detrimental ones and to develop defense responses. Here we review the mechanisms involved in these interactions. We also discuss how the interactions might be handled to improve crop resistance to pathogens without losing the ability to establish beneficial interactions.
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Affiliation(s)
- Benjamin Gourion
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Pascal Ratet
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France; Institute of Plant Sciences Paris-Saclay IPS2, Paris Diderot, Sorbonne Paris-Cité, Bâtiment 630, 91405, Orsay, France.
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15
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Torres-Martínez L, Porter SS, Wendlandt C, Purcell J, Ortiz-Barbosa G, Rothschild J, Lampe M, Warisha F, Le T, Weisberg AJ, Chang JH, Sachs JL. Evolution of specialization in a plant-microbial mutualism is explained by the oscillation theory of speciation. Evolution 2021; 75:1070-1086. [PMID: 33782951 DOI: 10.1111/evo.14222] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 02/18/2021] [Accepted: 03/14/2021] [Indexed: 12/11/2022]
Abstract
Specialization in mutualisms is thought to be a major driver of diversification, but few studies have explored how novel specialization evolves, or its relation to the evolution of other niche axes. A fundamental question is whether generalist interactions evolve to become more specialized (i.e., oscillation hypothesis) or if partner switches evolve without any change in niche breadth (i.e., musical chairs hypothesis). We examined alternative models for the evolution of specialization by estimating the mutualistic, climatic, and edaphic niche breadths of sister plant species, combining phylogenetic, environmental, and experimental data on Acmispon strigosus and Acmispon wrangelianus genotypes across their overlapping ranges in California. We found that specialization along all three niche axes was asymmetric across species, such that the species with broader climatic and edaphic niches, Acmispon strigosus, was also able to gain benefit from and invest in associating with a broader set of microbial mutualists. Our data are consistent with the oscillation model of specialization, and a parallel narrowing of the edaphic, climatic, and mutualistic dimensions of the host species niche. Our findings provide novel evidence that the evolution of specialization in mutualism is accompanied by specialization in other niche dimensions.
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Affiliation(s)
- Lorena Torres-Martínez
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, 92521
| | - Stephanie S Porter
- School of Biological Sciences, Washington State University, Vancouver, Washington, 98686, United States of America
| | - Camille Wendlandt
- School of Biological Sciences, Washington State University, Vancouver, Washington, 98686, United States of America
| | - Jessica Purcell
- Department of Entomology, University of California, Riverside, California, 92521, United States of America
| | - Gabriel Ortiz-Barbosa
- Department of Microbiology and Plant Pathology, University of California, Riverside, California, 92521, United States of America
| | - Jacob Rothschild
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, 92521
| | - Mathew Lampe
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, 92521
| | - Farsamin Warisha
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, 92521
| | - Tram Le
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, 92521
| | - Alexandra J Weisberg
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, 97331, United States of America
| | - Jeff H Chang
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, 97331, United States of America
| | - Joel L Sachs
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, 92521.,Department of Microbiology and Plant Pathology, University of California, Riverside, California, 92521, United States of America.,Institute of Integrative Genome Biology, University of California, Riverside, California, 92521, United States of America
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16
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Lineage-Specific Rewiring of Core Pathways Predating Innovation of Legume Nodules Shapes Symbiotic Efficiency. mSystems 2021; 6:6/2/e01299-20. [PMID: 33850043 PMCID: PMC8547004 DOI: 10.1128/msystems.01299-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The interkingdom coevolution innovated the rhizobium-legume symbiosis. The application of this nitrogen-fixing system in sustainable agriculture is usually impeded by incompatible interactions between partners. However, the progressive evolution of rhizobium-legume compatibility remains elusive. In this work, deletions of rhcV encoding a structural component of the type three secretion system allow related Sinorhizobium strains to nodulate a previously incompatible soybean cultivar (Glycine max). These rhcV mutants show low to medium to high symbiotic efficiency on the same cultivated soybean while being indistinguishable on wild soybean plants (Glycine soja). The dual pantranscriptomics reveals nodule-specific activation of core symbiosis genes of Sinorhizobium and Glycine genes associated with genome duplication events along the chronogram. Unexpectedly, symbiotic efficiency is in line with lineage-dependent transcriptional profiles of core pathways which predate the diversification of Fabaceae and Sinorhizobium. This is supported by further physiological and biochemical experiments. Particularly, low-efficiency nodules show disordered antioxidant activity and low-energy status, which restrict nitrogen fixation activity. Collectively, the ancient core pathways play a crucial role in optimizing the function of later-evolved mutualistic arsenals in the rhizobium-legume coevolution. IMPORTANCE Significant roles of complex extracellular microbiota in environmental adaptation of eukaryotes in ever-changing circumstances have been revealed. Given the intracellular infection ability, facultative endosymbionts can be considered pioneers within complex extracellular microbiota and are ideal organisms for understanding the early stage of interkingdom adaptation. This work reveals that the later innovation of key symbiotic arsenals and the lineage-specific network rewiring in ancient core pathways, predating the divergence of legumes and rhizobia, underline the progressive evolution of rhizobium-legume compatibility. This insight not only is significant for improving the application benefits of rhizobial inoculants in sustainable agriculture but also advances our general understanding of the interkingdom coevolution which is theoretically explored by all host-microbiota interactions.
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17
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Hazra KK, Nath CP, Singh SS, Swain DK, Kumar N, Das K, Lamichaney A. Categorization of Chickpea Nodules and Their Relation with Plant Growth. NATIONAL ACADEMY SCIENCE LETTERS 2021. [DOI: 10.1007/s40009-020-00972-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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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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19
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Fagorzi C, Bacci G, Huang R, Cangioli L, Checcucci A, Fini M, Perrin E, Natali C, diCenzo GC, Mengoni A. Nonadditive Transcriptomic Signatures of Genotype-by-Genotype Interactions during the Initiation of Plant-Rhizobium Symbiosis. mSystems 2021. [PMID: 33436514 DOI: 10.1101/2020.06.15.152710] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023] Open
Abstract
Rhizobia are ecologically important, facultative plant-symbiotic microbes. In nature, there is a large variability in the association of rhizobial strains and host plants of the same species. Here, we evaluated whether plant and rhizobial genotypes influence the initial transcriptional response of rhizobium following perception of a host plant. RNA sequencing of the model rhizobium Sinorhizobium meliloti exposed to root exudates or luteolin (an inducer of nod genes, involved in the early steps of symbiotic interaction) was performed on a combination of three S. meliloti strains and three alfalfa varieties as host plants. The response to root exudates involved hundreds of changes in the rhizobium transcriptome. Of the differentially expressed genes, 35% were influenced by the strain genotype, 16% were influenced by the plant genotype, and 29% were influenced by strain-by-host plant genotype interactions. We also examined the response of a hybrid S. meliloti strain in which the symbiotic megaplasmid (∼20% of the genome) was mobilized between two of the above-mentioned strains. Dozens of genes were upregulated in the hybrid strain, indicative of nonadditive variation in the transcriptome. In conclusion, this study demonstrated that transcriptional responses of rhizobia upon perception of legumes are influenced by the genotypes of both symbiotic partners and their interaction, suggesting a wide spectrum of genetic determinants involved in the phenotypic variation of plant-rhizobium symbiosis.IMPORTANCE A sustainable way for meeting the need of an increased global food demand should be based on a holobiont perspective, viewing crop plants as intimately associated with their microbiome, which helps improve plant nutrition, tolerance to pests, and adverse climate conditions. However, the genetic repertoire needed for efficient association with plants by the microbial symbionts is still poorly understood. The rhizobia are an exemplary model of facultative plant symbiotic microbes. Here, we evaluated whether genotype-by-genotype interactions could be identified in the initial transcriptional response of rhizobium perception of a host plant. We performed an RNA sequencing study to analyze the transcriptomes of different rhizobial strains elicited by root exudates of three alfalfa varieties as a proxy of an early step of the symbiotic interaction. The results indicated strain- and plant variety-dependent variability in the observed transcriptional changes, providing fundamentally novel insights into the genetic basis of rhizobium-plant interactions. Our results provide genetic insights and perspective to aid in the exploitation of natural rhizobium variation for improvement of legume growth in agricultural ecosystems.
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Affiliation(s)
- Camilla Fagorzi
- Department of Biology, University of Florence, Florence, Italy
| | - Giovanni Bacci
- Department of Biology, University of Florence, Florence, Italy
| | - Rui Huang
- Department of Biology, Queen's University, Kingston, Ontario, Canada
| | - Lisa Cangioli
- Department of Biology, University of Florence, Florence, Italy
| | - Alice Checcucci
- Department of Biology, University of Florence, Florence, Italy
| | - Margherita Fini
- Department of Biology, University of Florence, Florence, Italy
| | - Elena Perrin
- Department of Biology, University of Florence, Florence, Italy
| | - Chiara Natali
- Department of Biology, University of Florence, Florence, Italy
| | | | - Alessio Mengoni
- Department of Biology, University of Florence, Florence, Italy
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20
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Nonadditive Transcriptomic Signatures of Genotype-by-Genotype Interactions during the Initiation of Plant-Rhizobium Symbiosis. mSystems 2021; 6:6/1/e00974-20. [PMID: 33436514 PMCID: PMC7901481 DOI: 10.1128/msystems.00974-20] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Rhizobia are ecologically important, facultative plant-symbiotic microbes. In nature, there is a large variability in the association of rhizobial strains and host plants of the same species. Here, we evaluated whether plant and rhizobial genotypes influence the initial transcriptional response of rhizobium following perception of a host plant. RNA sequencing of the model rhizobium Sinorhizobium meliloti exposed to root exudates or luteolin (an inducer of nod genes, involved in the early steps of symbiotic interaction) was performed on a combination of three S. meliloti strains and three alfalfa varieties as host plants. The response to root exudates involved hundreds of changes in the rhizobium transcriptome. Of the differentially expressed genes, 35% were influenced by the strain genotype, 16% were influenced by the plant genotype, and 29% were influenced by strain-by-host plant genotype interactions. We also examined the response of a hybrid S. meliloti strain in which the symbiotic megaplasmid (∼20% of the genome) was mobilized between two of the above-mentioned strains. Dozens of genes were upregulated in the hybrid strain, indicative of nonadditive variation in the transcriptome. In conclusion, this study demonstrated that transcriptional responses of rhizobia upon perception of legumes are influenced by the genotypes of both symbiotic partners and their interaction, suggesting a wide spectrum of genetic determinants involved in the phenotypic variation of plant-rhizobium symbiosis.IMPORTANCE A sustainable way for meeting the need of an increased global food demand should be based on a holobiont perspective, viewing crop plants as intimately associated with their microbiome, which helps improve plant nutrition, tolerance to pests, and adverse climate conditions. However, the genetic repertoire needed for efficient association with plants by the microbial symbionts is still poorly understood. The rhizobia are an exemplary model of facultative plant symbiotic microbes. Here, we evaluated whether genotype-by-genotype interactions could be identified in the initial transcriptional response of rhizobium perception of a host plant. We performed an RNA sequencing study to analyze the transcriptomes of different rhizobial strains elicited by root exudates of three alfalfa varieties as a proxy of an early step of the symbiotic interaction. The results indicated strain- and plant variety-dependent variability in the observed transcriptional changes, providing fundamentally novel insights into the genetic basis of rhizobium-plant interactions. Our results provide genetic insights and perspective to aid in the exploitation of natural rhizobium variation for improvement of legume growth in agricultural ecosystems.
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21
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Tosi M, Gaiero J, Linton N, Mafa-Attoye T, Castillo A, Dunfield K. Bacterial Endophytes: Diversity, Functional Importance, and Potential for Manipulation. ACTA ACUST UNITED AC 2020. [DOI: 10.1007/978-981-15-6125-2_1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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22
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Kang W, Jiang Z, Chen Y, Wu F, Liu C, Wang H, Shi S, Zhang XX. Plant transcriptome analysis reveals specific molecular interactions between alfalfa and its rhizobial symbionts below the species level. BMC PLANT BIOLOGY 2020; 20:293. [PMID: 32590947 PMCID: PMC7318466 DOI: 10.1186/s12870-020-02503-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 06/18/2020] [Indexed: 05/22/2023]
Abstract
BACKGROUND Leguminous plants alter patterns of gene expression in response to symbiotic colonization and infection by their cognate rhizobial bacteria, but the extent of the transcriptomic response has rarely been examined below the species level. Here we describe the identification of 12 rhizobial biotypes of Ensifer meliloti, which form nitrogen-fixing nodules in the roots of alfalfa (Medicago sativa L.), followed by a comparative RNA-seq analysis of four alfalfa cultivars each inoculated with two E. meliloti strains varying in symbiotic performance and phylogenetic relatedness. RESULTS Rhizobial biotypes were identified on the basis of their symbiotic performance, particularly shoot dry weight. Differentially expressed genes (DEGs) and metabolic pathways were determined by comparing the RNA-seq data with that of the uninoculated control plant. Significant differences were found between DEGs generated in each cultivar with the inoculation of two rhizobial strains in comparison (P < 0.01). A total of 8111 genes was differentially expressed, representing ~ 17.1% of the M. sativa genome. The proportion of DEGs ranges from 0.5 to 12.2% for each alfalfa cultivar. Interestingly, genes with predicted roles in flavonoid biosynthesis and plant-pathogen interaction (NBS-LRR) were identified as the most significant DEGs. Other DEGs include Medsa002106 and genes encoding nodulins and NCR peptides whose expression is specifically induced during the development of nitrogen-fixing nodules. More importantly, strong significant positive correlations were observed between plant transcriptomes (DEGs and KEGG pathways) and phylogenetic distances between the two rhizobial inoculants. CONCLUSIONS Alfalfa expresses significantly distinct sets of genes in response to infection by different rhizobial strains at the below-species levels (i.e. biotype or strain). Candidate genes underlying the specific interactions include Medsa002106 and those encoding nodulins and NCR peptides and proteins in the NBS-LRR family.
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Affiliation(s)
- Wenjuan Kang
- College of Grassland Science, Gansu Agricultural University, Lanzhou, 730070, China
- School of Natural and Computational Sciences, Massey University at Albany, Auckland, 0745, New Zealand
| | - Zhehao Jiang
- College of Grassland Science, Gansu Agricultural University, Lanzhou, 730070, China
| | - Yonggang Chen
- College of Grassland Science, Gansu Agricultural University, Lanzhou, 730070, China
| | - Fang Wu
- College of Grassland Science, Gansu Agricultural University, Lanzhou, 730070, China
| | - Chang Liu
- College of Grassland Science, Gansu Agricultural University, Lanzhou, 730070, China
| | - Haifang Wang
- College of Life Science and Technology, Gansu Agricultural University, Lanzhou, 730070, China
| | - Shangli Shi
- College of Grassland Science, Gansu Agricultural University, Lanzhou, 730070, China.
- Key Laboratory of Grassland Ecosystem of the Chinese Ministry of Education, Lanzhou, 730070, China.
| | - Xue-Xian Zhang
- School of Natural and Computational Sciences, Massey University at Albany, Auckland, 0745, New Zealand
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23
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Mergaert P. Role of antimicrobial peptides in controlling symbiotic bacterial populations. Nat Prod Rep 2019; 35:336-356. [PMID: 29393944 DOI: 10.1039/c7np00056a] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Covering: up to 2018 Antimicrobial peptides (AMPs) have been known for well over three decades as crucial mediators of the innate immune response in animals and plants, where they are involved in the killing of infecting microbes. However, AMPs have now also been found to be produced by eukaryotic hosts during symbiotic interactions with bacteria. These symbiotic AMPs target the symbionts and therefore have a more subtle biological role: not eliminating the microbial symbiont population but rather keeping it in check. The arsenal of AMPs and the symbionts' adaptations to resist them are in a careful balance, which contributes to the establishment of the host-microbe homeostasis. Although in many cases the biological roles of symbiotic AMPs remain elusive, for a number of symbiotic interactions, precise functions have been assigned or proposed to the AMPs, which are discussed here. The microbiota living on epithelia in animals, from the most primitive ones to the mammals, are challenged by a cocktail of AMPs that determine the specific composition of the bacterial community as well as its spatial organization. In the symbiosis of legume plants with nitrogen-fixing rhizobium bacteria, the host deploys an extremely large panel of AMPs - called nodule-specific cysteine-rich (NCR) peptides - that drive the bacteria into a terminally differentiated state and manipulate the symbiont physiology to maximize the benefit for the host. The NCR peptides are used as tools to enslave the bacterial symbionts, limiting their reproduction but keeping them metabolically active for nitrogen fixation. In the nutritional symbiotic interactions of insects and protists that have vertically transmitted bacterial symbionts with reduced genomes, symbiotic AMPs could facilitate the integration of the endosymbiont and host metabolism by favouring the flow of metabolites across the symbiont membrane through membrane permeabilization.
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Affiliation(s)
- P Mergaert
- Institute for Integrative Biology of the Cell, UMR9198, CNRS, Université Paris-Sud, CEA, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France.
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Trujillo DI, Silverstein KAT, Young ND. Nodule-specific PLAT domain proteins are expanded in the Medicago lineage and required for nodulation. THE NEW PHYTOLOGIST 2019; 222:1538-1550. [PMID: 30664233 DOI: 10.1111/nph.15697] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 01/03/2019] [Indexed: 06/09/2023]
Abstract
Symbiotic nitrogen fixation in legumes is mediated by an interplay of signaling processes between plant hosts and rhizobial symbionts. In legumes, several secreted protein families have undergone expansions and play key roles in nodulation. Thus, identifying lineage-specific expansions (LSEs) of nodulation-associated genes can be a strategy to discover candidate gene families. Using bioinformatic tools, we identified 13 LSEs of nodulation-related secreted protein families, each unique to either Glycine, Arachis or Medicago lineages. In the Medicago lineage, nodule-specific Polycystin-1, Lipoxygenase, Alpha Toxin (PLAT) domain proteins (NPDs) expanded to five members. We examined NPD function using CRISPR/Cas9 multiplex genome editing to create Medicago truncatula NPD knockout lines, targeting one to five NPD genes. Mutant lines with differing combinations of NPD gene inactivations had progressively smaller nodules, earlier onset of nodule senescence, or ineffective nodules compared to the wild-type control. Double- and triple-knockout lines showed dissimilar nodulation phenotypes but coincided in upregulation of a DHHC-type zinc finger and an aspartyl protease gene, possible candidates for the observed disturbance of proper nodule function. By postulating that gene family expansions can be used to detect candidate genes, we identified a family of nodule-specific PLAT domain proteins and confirmed that they play a role in successful nodule formation.
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Affiliation(s)
- Diana I Trujillo
- Department of Plant Biology, University of Minnesota, Saint Paul, MN, 55108, USA
| | - Kevin A T Silverstein
- Supercomputing Institute for Advanced Computational Research, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Nevin D Young
- Department of Plant Pathology, University of Minnesota, Saint Paul, MN, 55108, USA
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25
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diCenzo GC, Zamani M, Checcucci A, Fondi M, Griffitts JS, Finan TM, Mengoni A. Multidisciplinary approaches for studying rhizobium–legume symbioses. Can J Microbiol 2019; 65:1-33. [DOI: 10.1139/cjm-2018-0377] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The rhizobium–legume symbiosis is a major source of fixed nitrogen (ammonia) in the biosphere. The potential for this process to increase agricultural yield while reducing the reliance on nitrogen-based fertilizers has generated interest in understanding and manipulating this process. For decades, rhizobium research has benefited from the use of leading techniques from a very broad set of fields, including population genetics, molecular genetics, genomics, and systems biology. In this review, we summarize many of the research strategies that have been employed in the study of rhizobia and the unique knowledge gained from these diverse tools, with a focus on genome- and systems-level approaches. We then describe ongoing synthetic biology approaches aimed at improving existing symbioses or engineering completely new symbiotic interactions. The review concludes with our perspective of the future directions and challenges of the field, with an emphasis on how the application of a multidisciplinary approach and the development of new methods will be necessary to ensure successful biotechnological manipulation of the symbiosis.
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Affiliation(s)
- George C. diCenzo
- Department of Biology, University of Florence, Sesto Fiorentino, FI 50019, Italy
| | - Maryam Zamani
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Alice Checcucci
- Department of Biology, University of Florence, Sesto Fiorentino, FI 50019, Italy
| | - Marco Fondi
- Department of Biology, University of Florence, Sesto Fiorentino, FI 50019, Italy
| | - Joel S. Griffitts
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT 84602, USA
| | - Turlough M. Finan
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Alessio Mengoni
- Department of Biology, University of Florence, Sesto Fiorentino, FI 50019, Italy
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26
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Checcucci A, diCenzo GC, Ghini V, Bazzicalupo M, Becker A, Decorosi F, Döhlemann J, Fagorzi C, Finan TM, Fondi M, Luchinat C, Turano P, Vignolini T, Viti C, Mengoni A. Creation and Characterization of a Genomically Hybrid Strain in the Nitrogen-Fixing Symbiotic Bacterium Sinorhizobium meliloti. ACS Synth Biol 2018; 7:2365-2378. [PMID: 30223644 DOI: 10.1021/acssynbio.8b00158] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Many bacteria, often associated with eukaryotic hosts and of relevance for biotechnological applications, harbor a multipartite genome composed of more than one replicon. Biotechnologically relevant phenotypes are often encoded by genes residing on the secondary replicons. A synthetic biology approach to developing enhanced strains for biotechnological purposes could therefore involve merging pieces or entire replicons from multiple strains into a single genome. Here we report the creation of a genomic hybrid strain in a model multipartite genome species, the plant-symbiotic bacterium Sinorhizobium meliloti. We term this strain as cis-hybrid, since it is produced by genomic material coming from the same species' pangenome. In particular, we moved the secondary replicon pSymA (accounting for nearly 20% of total genome content) from a donor S. meliloti strain to an acceptor strain. The cis-hybrid strain was screened for a panel of complex phenotypes (carbon/nitrogen utilization phenotypes, intra- and extracellular metabolomes, symbiosis, and various microbiological tests). Additionally, metabolic network reconstruction and constraint-based modeling were employed for in silico prediction of metabolic flux reorganization. Phenotypes of the cis-hybrid strain were in good agreement with those of both parental strains. Interestingly, the symbiotic phenotype showed a marked cultivar-specific improvement with the cis-hybrid strains compared to both parental strains. These results provide a proof-of-principle for the feasibility of genome-wide replicon-based remodelling of bacterial strains for improved biotechnological applications in precision agriculture.
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Affiliation(s)
- Alice Checcucci
- Department of Biology, University of Florence, 50019 Sesto Fiorentino, Italy
| | - George C. diCenzo
- Department of Biology, University of Florence, 50019 Sesto Fiorentino, Italy
| | - Veronica Ghini
- CERM & CIRMMP, University of Florence, 50019 Sesto Fiorentino, Italy
| | - Marco Bazzicalupo
- Department of Biology, University of Florence, 50019 Sesto Fiorentino, Italy
| | - Anke Becker
- LOEWE − Center for Synthetic Microbiology, 35043 Marburg, Germany
| | - Francesca Decorosi
- Department of Agri-food Production and Environmental Science, University of Florence, 50019 Florence, Italy
| | | | - Camilla Fagorzi
- Department of Biology, University of Florence, 50019 Sesto Fiorentino, Italy
| | - Turlough M. Finan
- Department of Biology, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - Marco Fondi
- Department of Biology, University of Florence, 50019 Sesto Fiorentino, Italy
| | - Claudio Luchinat
- CERM & CIRMMP, University of Florence, 50019 Sesto Fiorentino, Italy
- CERM and Department of Chemistry, University of Florence, 50019 Sesto Fiorentino, Italy
| | - Paola Turano
- CERM & CIRMMP, University of Florence, 50019 Sesto Fiorentino, Italy
- CERM and Department of Chemistry, University of Florence, 50019 Sesto Fiorentino, Italy
| | - Tiziano Vignolini
- European Laboratory for Non-Linear Spectroscopy, LENS, 50019 Sesto Fiorentino, Italy
| | - Carlo Viti
- Department of Agri-food Production and Environmental Science, University of Florence, 50019 Florence, Italy
| | - Alessio Mengoni
- Department of Biology, University of Florence, 50019 Sesto Fiorentino, Italy
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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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28
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Palakurty SX, Stinchcombe JR, Afkhami ME. Cooperation and coexpression: How coexpression networks shift in response to multiple mutualists. Mol Ecol 2018. [DOI: 10.1111/mec.14550] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
| | - John R. Stinchcombe
- Department of Ecology and Evolutionary Biology University of Toronto Toronto ON Canada
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29
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Clúa J, Roda C, Zanetti ME, Blanco FA. Compatibility between Legumes and Rhizobia for the Establishment of a Successful Nitrogen-Fixing Symbiosis. Genes (Basel) 2018; 9:E125. [PMID: 29495432 PMCID: PMC5867846 DOI: 10.3390/genes9030125] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 01/24/2018] [Accepted: 02/08/2018] [Indexed: 12/14/2022] Open
Abstract
The root nodule symbiosis established between legumes and rhizobia is an exquisite biological interaction responsible for fixing a significant amount of nitrogen in terrestrial ecosystems. The success of this interaction depends on the recognition of the right partner by the plant within the richest microbial ecosystems on Earth, the soil. Recent metagenomic studies of the soil biome have revealed its complexity, which includes microorganisms that affect plant fitness and growth in a beneficial, harmful, or neutral manner. In this complex scenario, understanding the molecular mechanisms by which legumes recognize and discriminate rhizobia from pathogens, but also between distinct rhizobia species and strains that differ in their symbiotic performance, is a considerable challenge. In this work, we will review how plants are able to recognize and select symbiotic partners from a vast diversity of surrounding bacteria. We will also analyze recent advances that contribute to understand changes in plant gene expression associated with the outcome of the symbiotic interaction. These aspects of nitrogen-fixing symbiosis should contribute to translate the knowledge generated in basic laboratory research into biotechnological advances to improve the efficiency of the nitrogen-fixing symbiosis in agronomic systems.
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Affiliation(s)
- Joaquín Clúa
- Instituto de Biotecnología y Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Centro Científico y Tecnológico-La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, 1900-La Plata, Argentina.
| | - Carla Roda
- Instituto de Biotecnología y Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Centro Científico y Tecnológico-La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, 1900-La Plata, Argentina.
| | - María Eugenia Zanetti
- Instituto de Biotecnología y Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Centro Científico y Tecnológico-La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, 1900-La Plata, Argentina.
| | - Flavio A Blanco
- Instituto de Biotecnología y Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Centro Científico y Tecnológico-La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, 1900-La Plata, Argentina.
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30
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Select and resequence reveals relative fitness of bacteria in symbiotic and free-living environments. Proc Natl Acad Sci U S A 2018; 115:2425-2430. [PMID: 29453274 DOI: 10.1073/pnas.1714246115] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Assays to accurately estimate relative fitness of bacteria growing in multistrain communities can advance our understanding of how selection shapes diversity within a lineage. Here, we present a variant of the "evolve and resequence" approach both to estimate relative fitness and to identify genetic variants responsible for fitness variation of symbiotic bacteria in free-living and host environments. We demonstrate the utility of this approach by characterizing selection by two plant hosts and in two free-living environments (sterilized soil and liquid media) acting on synthetic communities of the facultatively symbiotic bacterium Ensifer meliloti We find (i) selection that hosts exert on rhizobial communities depends on competition among strains, (ii) selection is stronger inside hosts than in either free-living environment, and (iii) a positive host-dependent relationship between relative strain fitness in multistrain communities and host benefits provided by strains in single-strain experiments. The greatest changes in allele frequencies in response to plant hosts are in genes associated with motility, regulation of nitrogen fixation, and host/rhizobia signaling. The approach we present provides a powerful complement to experimental evolution and forward genetic screens for characterizing selection in bacterial populations, identifying gene function, and surveying the functional importance of naturally occurring genomic variation.
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