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Gasser M, Keller J, Fournier P, Pujic P, Normand P, Boubakri H. Identification and evolution of nsLTPs in the root nodule nitrogen fixation clade and molecular response of Frankia to AgLTP24. Sci Rep 2023; 13:16020. [PMID: 37749152 PMCID: PMC10520049 DOI: 10.1038/s41598-023-41117-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 08/22/2023] [Indexed: 09/27/2023] Open
Abstract
Non-specific lipid transfer proteins (nsLTPs) are antimicrobial peptides, involved in several plant biological processes including root nodule nitrogen fixation (RNF). Nodulating plants belonging to the RNF clade establish symbiosis with the nitrogen-fixing bacteria rhizobia (legumes symbiosis model) and Frankia (actinorhizal symbiosis model) leading to root nodule formation. nsLTPs are involved in processes active in early step of symbiosis and functional nodule in both models. In legumes, nsLTPs have been shown to regulate symbiont entry, promote root cortex infection, membrane biosynthesis, and improve symbiosis efficiency. More recently, a nsLTP, AgLTP24 has been described in the context of actinorhizal symbiosis between Alnus glutinosa and Frankia alni ACN14a. AgLTP24 is secreted at an early step of symbiosis on the deformed root hairs and targets the symbiont in the nitrogen-fixing vesicles in functional nodules. nsLTPs are involved in RNF, but their functions and evolutionary history are still largely unknown. Numerous putative nsLTPs were found up-regulated in functional nodules compared to non-infected roots in different lineages within the RNF clade. Here, results highlight that nodulating plants that are co-evolving with their nitrogen-fixing symbionts appear to have independently specialized nsLTPs for this interaction, suggesting a possible convergence of function, which opens perspectives to investigate nsLTPs functions in RNF.
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Affiliation(s)
- Mélanie Gasser
- Universite Claude Bernard Lyon 1, Laboratoire d'Ecologie Microbienne, UMR CNRS 5557, UMR INRAE 1418, VetAgro Sup, 69622, Villeurbanne, France
| | - Jean Keller
- LRSV, Université de Toulouse, CNRS, UPS, Toulouse INP, Castanet-Tolosan, France
| | - Pascale Fournier
- Universite Claude Bernard Lyon 1, Laboratoire d'Ecologie Microbienne, UMR CNRS 5557, UMR INRAE 1418, VetAgro Sup, 69622, Villeurbanne, France
| | - Petar Pujic
- Universite Claude Bernard Lyon 1, Laboratoire d'Ecologie Microbienne, UMR CNRS 5557, UMR INRAE 1418, VetAgro Sup, 69622, Villeurbanne, France
| | - Philippe Normand
- Universite Claude Bernard Lyon 1, Laboratoire d'Ecologie Microbienne, UMR CNRS 5557, UMR INRAE 1418, VetAgro Sup, 69622, Villeurbanne, France
| | - Hasna Boubakri
- Universite Claude Bernard Lyon 1, Laboratoire d'Ecologie Microbienne, UMR CNRS 5557, UMR INRAE 1418, VetAgro Sup, 69622, Villeurbanne, France.
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Abstract
Plants associate with nitrogen-fixing bacteria to secure nitrogen, which is generally the most limiting nutrient for plant growth. Endosymbiotic nitrogen-fixing associations are widespread among diverse plant lineages, ranging from microalgae to angiosperms, and are primarily one of three types: cyanobacterial, actinorhizal or rhizobial. The large overlap in the signaling pathways and infection components of arbuscular mycorrhizal, actinorhizal and rhizobial symbioses reflects their evolutionary relatedness. These beneficial associations are influenced by environmental factors and other microorganisms in the rhizosphere. In this review, we summarize the diversity of nitrogen-fixing symbioses, key signal transduction pathways and colonization mechanisms relevant to such interactions, and compare and contrast these interactions with arbuscular mycorrhizal associations from an evolutionary standpoint. Additionally, we highlight recent studies on environmental factors regulating nitrogen-fixing symbioses to provide insights into the adaptation of symbiotic plants to complex environments.
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Affiliation(s)
- Peng Xu
- National key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Ertao Wang
- National key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; New Cornerstone Science Laboratory, Shenzhen 518054, China.
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3
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Kucho KI, Asukai K, Nguyen TV. NAD + Synthetase is Required for Free-living and Symbiotic Nitrogen Fixation in the Actinobacterium Frankia casuarinae. Microbes Environ 2023; 38. [PMID: 36858533 PMCID: PMC10037102 DOI: 10.1264/jsme2.me22093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023] Open
Abstract
Frankia spp. are multicellular actinobacteria that fix atmospheric dinitrogen (N2) not only in the free-living state, but also in root-nodule symbioses with more than 200 plant species, called actinorhizal plants. To identify novel Frankia genes involved in N2 fixation, we previously isolated mutants of Frankia casuarinae that cannot fix N2. One of these genes, mutant N3H4, did not induce nodulation when inoculated into the host plant Casuarina glauca. Cell lineages that regained the ability to fix N2 as free-living cells were isolated from the mutant cell population. These restored strains also regained the ability to stimulate nodulation. A comparative ana-lysis of the genomes of mutant N3H4 and restored strains revealed that the mutant carried a mutation (Thr584Ile) in the glutamine-dependent NAD+ synthetase gene (Francci3_3146), while restored strains carried an additional suppressor mutation (Asp478Asn) in the same gene. Under nitrogen-depleted conditions, the concentration of NAD(H) was markedly lower in the mutant strain than in the wild type, whereas it was higher in restored strains. These results indicate that glutamine-dependent NAD+ synthetase plays critical roles in both free-living and symbiotic N2 fixation in Frankia.
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Affiliation(s)
- Ken-Ichi Kucho
- Graduate School of Science and Engineering, Kagoshima University
| | - Koya Asukai
- Graduate School of Science and Engineering, Kagoshima University
| | - Thanh Van Nguyen
- Graduate School of Science and Engineering, Kagoshima University
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Salgado MG, Demina IV, Maity PJ, Nagchowdhury A, Caputo A, Krol E, Loderer C, Muth G, Becker A, Pawlowski K. Legume NCRs and nodule-specific defensins of actinorhizal plants—Do they share a common origin? PLoS One 2022; 17:e0268683. [PMID: 35980975 PMCID: PMC9387825 DOI: 10.1371/journal.pone.0268683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 05/04/2022] [Indexed: 11/20/2022] Open
Abstract
The actinorhizal plant Datisca glomerata (Datiscaceae, Cucurbitales) establishes a root nodule symbiosis with actinobacteria from the earliest branching symbiotic Frankia clade. A subfamily of a gene family encoding nodule-specific defensin-like cysteine-rich peptides is highly expressed in D. glomerata nodules. Phylogenetic analysis of the defensin domain showed that these defensin-like peptides share a common evolutionary origin with nodule-specific defensins from actinorhizal Fagales and with nodule-specific cysteine-rich peptides (NCRs) from legumes. In this study, the family member with the highest expression levels, DgDef1, was characterized. Promoter-GUS studies on transgenic hairy roots showed expression in the early stage of differentiation of infected cells, and transient expression in the nodule apex. DgDef1 contains an N-terminal signal peptide and a C-terminal acidic domain which are likely involved in subcellular targeting and do not affect peptide activity. In vitro studies with E. coli and Sinorhizobium meliloti 1021 showed that the defensin domain of DgDef1 has a cytotoxic effect, leading to membrane disruption with 50% lethality for S. meliloti 1021 at 20.8 μM. Analysis of the S. meliloti 1021 transcriptome showed that, at sublethal concentrations, DgDef1 induced the expression of terminal quinol oxidases, which are associated with the oxidative stress response and are also expressed during symbiosis. Overall, the changes induced by DgDef1 are reminiscent of those of some legume NCRs, suggesting that nodule-specific defensin-like peptides were part of the original root nodule toolkit and were subsequently lost in most symbiotic legumes, while being maintained in the actinorhizal lineages.
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Affiliation(s)
- Marco Guedes Salgado
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Irina V Demina
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Pooja Jha Maity
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Anurupa Nagchowdhury
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Andrea Caputo
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Elizaveta Krol
- Center for Synthetic Microbiology, Philipps-Universität Marburg, Marburg, Germany
- Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Christoph Loderer
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Günther Muth
- Department of Microbial Bioactive Compounds, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Eberhard Karls University Tübingen, Tübingen, Germany
| | - Anke Becker
- Center for Synthetic Microbiology, Philipps-Universität Marburg, Marburg, Germany
- Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Katharina Pawlowski
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
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Gueddou A, Sarker I, Sen A, Ghodhbane-Gtari F, Benson DR, Armengaud J, Gtari M. Effect of actinorhizal root exudates on the proteomes of Frankia soli NRRL B-16219, a strain colonizing the root tissues of its actinorhizal host via intercellular pathway. Res Microbiol 2021; 173:103900. [PMID: 34800660 DOI: 10.1016/j.resmic.2021.103900] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 11/08/2021] [Accepted: 11/09/2021] [Indexed: 12/27/2022]
Abstract
Frankia and actinorhizal plants exchange signals in the rhizosphere leading to specific mutual recognition of partners and nitrogen-fixing nodule organogenesis. Frankia soli strain NRRL B-16219, from the Elaeagnus specificity group, colonizes the root tissues of its actinorhizal host through direct intercellular penetration of root epidermis cells and cortex. Here, we studied the early proteogenomic response of strain NRRL B-16219 to treatment with root exudates from compatible Elaeagnus angustifolia, and incompatible Ceanothus thyrsiflorus and Coriaria myrtifolia, host plants grown in nitrogen depleted hydroponic medium. Next-generation proteomics was used to identify the main Frankia proteins differentially expressed in response to the root exudates. No products of the nod genes present in B-16219 were detected. Proteins specifically upregulated in presence of E. angustifolia root exudates include those connected to nitrogen fixation and assimilation (glutamate synthetase, hydrogenase and squalene synthesis), respiration (oxidative phosphorylation and citric acid cycle pathways), oxidative stress (catalase, superoxide dismutase, and peroxidase), proteolysis (proteasome, protease, and peptidase) and plant cell wall degrading proteins involved in the depolymerization of celluloses (endoglucanase, glycosyltransferase, beta-mannanases, glycoside hydrolase and glycosyl hydrolase). Proteomic data obtained in this study will help link signaling molecules/factors to their biosynthetic pathways once those factors have been fully characterized.
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Affiliation(s)
- Abdellatif Gueddou
- USCR Bactériologie Moléculaire & Génomique, Institut National des Sciences Appliquées et de Technologie, Université Carthage, Centre Urbain Nord, BP 676-1080, Tunis Cedex, Tunisia; LR Microorganismes & Biomolécules Actives, Faculté des Sciences de Tunis, Université Tunis El Manar, 2092 - El Manar Tunisia
| | - Indrani Sarker
- Bioinformatics Facility, University of North Bengal, Siliguri, India
| | - Arnab Sen
- Bioinformatics Facility, University of North Bengal, Siliguri, India
| | - Faten Ghodhbane-Gtari
- USCR Bactériologie Moléculaire & Génomique, Institut National des Sciences Appliquées et de Technologie, Université Carthage, Centre Urbain Nord, BP 676-1080, Tunis Cedex, Tunisia; LR Microorganismes & Biomolécules Actives, Faculté des Sciences de Tunis, Université Tunis El Manar, 2092 - El Manar Tunisia
| | - David R Benson
- Department of Molecular and Cell Biology, U-3125, University of Connecticut, Storrs, CT, USA
| | - Jean Armengaud
- Laboratoire Innovations Technologiques pour La Détection et le Diagnostic (Li2D), Service de Pharmacologie et Immunoanalyse (SPI), CEA, INRA, F-30207 Bagnols-sur-Cèze, France
| | - Maher Gtari
- USCR Bactériologie Moléculaire & Génomique, Institut National des Sciences Appliquées et de Technologie, Université Carthage, Centre Urbain Nord, BP 676-1080, Tunis Cedex, Tunisia; LR Microorganismes & Biomolécules Actives, Faculté des Sciences de Tunis, Université Tunis El Manar, 2092 - El Manar Tunisia.
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Rutten L, Miyata K, Roswanjaya YP, Huisman R, Bu F, Hartog M, Linders S, van Velzen R, van Zeijl A, Bisseling T, Kohlen W, Geurts R. Duplication of Symbiotic Lysin Motif Receptors Predates the Evolution of Nitrogen-Fixing Nodule Symbiosis. PLANT PHYSIOLOGY 2020; 184:1004-1023. [PMID: 32669419 PMCID: PMC7536700 DOI: 10.1104/pp.19.01420] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 07/07/2020] [Indexed: 05/02/2023]
Abstract
Rhizobium nitrogen-fixing nodule symbiosis occurs in two taxonomic lineages: legumes (Fabaceae) and the genus Parasponia (Cannabaceae). Both symbioses are initiated upon the perception of rhizobium-secreted lipochitooligosaccharides (LCOs), called Nod factors. Studies in the model legumes Lotus japonicus and Medicago truncatula showed that rhizobium LCOs are perceived by a heteromeric receptor complex of distinct Lys motif (LysM)-type transmembrane receptors named NOD FACTOR RECEPTOR1 (LjNFR1) and LjNFR5 (L. japonicus) and LYSM DOMAIN CONTAINING RECEPTOR KINASE3 (MtLYK3)-NOD FACTOR PERCEPTION (MtNFP; M. truncatula). Recent phylogenomic comparative analyses indicated that the nodulation traits of legumes, Parasponia spp., as well as so-called actinorhizal plants that establish a symbiosis with diazotrophic Frankia spp. bacteria share an evolutionary origin about 110 million years ago. However, the evolutionary trajectory of LysM-type LCO receptors remains elusive. By conducting phylogenetic analysis, transcomplementation studies, and CRISPR-Cas9 mutagenesis in Parasponia andersonii, we obtained insight into the origin of LCO receptors essential for nodulation. We identified four LysM-type receptors controlling nodulation in P. andersonii: PanLYK1, PanLYK3, PanNFP1, and PanNFP2 These genes evolved from ancient duplication events predating and coinciding with the origin of nodulation. Phylogenetic and functional analyses associated the occurrence of a functional NFP2-orthologous receptor to LCO-driven nodulation. Legumes and Parasponia spp. use orthologous LysM-type receptors to perceive rhizobium LCOs, suggesting a shared evolutionary origin of LCO-driven nodulation. Furthermore, we found that both PanLYK1 and PanLYK3 are essential for intracellular arbuscule formation of mutualistic endomycorrhizal fungi. PanLYK3 also acts as a chitin oligomer receptor essential for innate immune signaling, demonstrating functional analogy to CHITIN ELECITOR RECEPTOR KINASE-type receptors.
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Affiliation(s)
- Luuk Rutten
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Kana Miyata
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Yuda Purwana Roswanjaya
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
- Centre of Technology for Agricultural Production, Agency for the Assessment and Application of Technology, 10340 Jakarta, Indonesia
| | - Rik Huisman
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Fengjiao Bu
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Marijke Hartog
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Sidney Linders
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Robin van Velzen
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
- Biosystematics Group, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Arjan van Zeijl
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Ton Bisseling
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Wouter Kohlen
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Rene Geurts
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
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Huisman R, Geurts R. A Roadmap toward Engineered Nitrogen-Fixing Nodule Symbiosis. PLANT COMMUNICATIONS 2020; 1:100019. [PMID: 33404552 PMCID: PMC7748023 DOI: 10.1016/j.xplc.2019.100019] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 11/06/2019] [Accepted: 12/27/2019] [Indexed: 05/26/2023]
Abstract
In the late 19th century, it was discovered that legumes can establish a root nodule endosymbiosis with nitrogen-fixing rhizobia. Soon after, the question was raised whether it is possible to transfer this trait to non-leguminous crops. In the past century, an ever-increasing amount of knowledge provided unique insights into the cellular, molecular, and genetic processes controlling this endosymbiosis. In addition, recent phylogenomic studies uncovered several genes that evolved to function specifically to control nodule formation and bacterial infection. However, despite this massive body of knowledge, the long-standing objective to engineer the nitrogen-fixing nodulation trait on non-leguminous crop plants has not been achieved yet. In this review, the unsolved questions and engineering strategies toward nitrogen-fixing nodulation in non-legume plants are discussed and highlighted.
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Affiliation(s)
- Rik Huisman
- Wageningen University, Department of Plant Sciences, Laboratory of Molecular Biology, Droevendaalsesteeg 1, Wageningen 6708PB, The Netherlands
| | - Rene Geurts
- Wageningen University, Department of Plant Sciences, Laboratory of Molecular Biology, Droevendaalsesteeg 1, Wageningen 6708PB, The Netherlands
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Mergaert P, Kereszt A, Kondorosi E. Gene Expression in Nitrogen-Fixing Symbiotic Nodule Cells in Medicago truncatula and Other Nodulating Plants. THE PLANT CELL 2020; 32:42-68. [PMID: 31712407 PMCID: PMC6961632 DOI: 10.1105/tpc.19.00494] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 11/08/2019] [Indexed: 05/06/2023]
Abstract
Root nodules formed by plants of the nitrogen-fixing clade (NFC) are symbiotic organs that function in the maintenance and metabolic integration of large populations of nitrogen-fixing bacteria. These organs feature unique characteristics and processes, including their tissue organization, the presence of specific infection structures called infection threads, endocytotic uptake of bacteria, symbiotic cells carrying thousands of intracellular bacteria without signs of immune responses, and the integration of symbiont and host metabolism. The early stages of nodulation are governed by a few well-defined functions, which together constitute the common symbiosis-signaling pathway (CSSP). The CSSP activates a set of transcription factors (TFs) that orchestrate nodule organogenesis and infection. The later stages of nodule development require the activation of hundreds to thousands of genes, mostly expressed in symbiotic cells. Many of these genes are only active in symbiotic cells, reflecting the unique nature of nodules as plant structures. Although how the nodule-specific transcriptome is activated and connected to early CSSP-signaling is poorly understood, candidate TFs have been identified using transcriptomic approaches, and the importance of epigenetic and chromatin-based regulation has been demonstrated. We discuss how gene regulation analyses have advanced our understanding of nodule organogenesis, the functioning of symbiotic cells, and the evolution of symbiosis in the NFC.
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Affiliation(s)
- Peter Mergaert
- Institute for Integrative Biology of the Cell, UMR 9198, CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Attila Kereszt
- Institute of Plant Biology, Biological Research Centre, 6726 Szeged, Hungary
| | - Eva Kondorosi
- Institute of Plant Biology, Biological Research Centre, 6726 Szeged, Hungary
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Shen D, Bisseling T. The Evolutionary Aspects of Legume Nitrogen-Fixing Nodule Symbiosis. Results Probl Cell Differ 2020; 69:387-408. [PMID: 33263880 DOI: 10.1007/978-3-030-51849-3_14] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Nitrogen-fixing root nodule symbiosis can sustain the development of the host plants under nitrogen-limiting conditions. Such symbiosis occurs only in a clade of angiosperms known as the nitrogen-fixing clade (NFC). It has long been proposed that root nodule symbiosis evolved several times (in parallel) in the NFC. Two recent phylogenomic studies compared the genomes of nodulating and related non-nodulating species across the four orders of the NFC and found that genes essential for nodule formation are lost or pseudogenized in the non-nodulating species. As these symbiosis genes are specifically involved in the symbiotic interaction, it means that the presence of pseudogenes and the loss of symbiosis genes strongly suggest that their ancestor, which still had functional genes, most likely had a symbiosis with nitrogen-fixing bacteria. These findings agree with the hypothesis that nodulation evolved once at the common ancestor of the NFC, and challenge the hypothesis of parallel evolution. In this chapter, we will cover the current understandings on actinorhizal-type and legume nodule development, and discuss the evolution of the legume nodule type.
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Affiliation(s)
- Defeng Shen
- Laboratory of Molecular Biology, Graduate School Experimental Plant Sciences, Wageningen University, Wageningen, The Netherlands
| | - Ton Bisseling
- Laboratory of Molecular Biology, Graduate School Experimental Plant Sciences, Wageningen University, Wageningen, The Netherlands.
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