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García-Soto I, Andersen SU, Monroy-Morales E, Robledo-Gamboa M, Guadarrama J, Aviles-Baltazar NY, Serrano M, Stougaard J, Montiel J. A collection of novel Lotus japonicus LORE1 mutants perturbed in the nodulation program induced by the Agrobacterium pusense strain IRBG74. FRONTIERS IN PLANT SCIENCE 2024; 14:1326766. [PMID: 38250449 PMCID: PMC10796720 DOI: 10.3389/fpls.2023.1326766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 12/12/2023] [Indexed: 01/23/2024]
Abstract
The Lotus japonicus population carrying new Lotus retrotransposon 1 (LORE1) insertions represents a valuable biological resource for genetic research. New insertions were generated by activation of the endogenous retroelement LORE1a in the germline of the G329-3 plant line and arranged in a 2-D system for reverse genetics. LORE1 mutants identified in this collection contributes substantially to characterize candidate genes involved in symbiotic association of L. japonicus with its cognate symbiont, the nitrogen-fixing bacteria Mesorhizobium loti that infects root nodules intracellularly. In this study we aimed to identify novel players in the poorly explored intercellular infection induced by Agrobacterium pusense IRBG74 sp. For this purpose, a forward screen of > 200,000 LORE1 seedlings, obtained from bulk propagation of G329-3 plants, inoculated with IRBG74 was performed. Plants with perturbed nodulation were scored and the offspring were further tested on plates to confirm the symbiotic phenotype. A total of 110 Lotus mutants with impaired nodulation after inoculation with IRBG74 were obtained. A comparative analysis of nodulation kinetics in a subset of 20 mutants showed that most of the lines were predominantly affected in nodulation by IRBG74. Interestingly, additional defects in the main root growth were observed in some mutant lines. Sequencing of LORE1 flanking regions in 47 mutants revealed that 92 Lotus genes were disrupted by novel LORE1 insertions in these lines. In the IM-S34 mutant, one of the insertions was located in the 5´UTR of the LotjaGi5g1v0179800 gene, which encodes the AUTOPHAGY9 protein. Additional mutant alleles, named atg9-2 and atg9-3, were obtained in the reverse genetic collection. Nodule formation was significantly reduced in these mutant alleles after M. loti and IRBG74 inoculation, confirming the effectiveness of the mutant screening. This study describes an effective forward genetic approach to obtain novel mutants in Lotus with a phenotype of interest and to identify the causative gene(s).
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Affiliation(s)
- Ivette García-Soto
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mexico
| | - Stig U. Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Elizabeth Monroy-Morales
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mexico
| | - Mariana Robledo-Gamboa
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mexico
| | - Jesús Guadarrama
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mexico
| | | | - Mario Serrano
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mexico
| | - Jens Stougaard
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Jesús Montiel
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mexico
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Oxidative Status of Medicago truncatula Seedlings after Inoculation with Rhizobacteria of the Genus Pseudomonas, Paenibacillus and Sinorhizobium. Int J Mol Sci 2023; 24:ijms24054781. [PMID: 36902209 PMCID: PMC10003724 DOI: 10.3390/ijms24054781] [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: 01/31/2023] [Revised: 02/21/2023] [Accepted: 02/28/2023] [Indexed: 03/06/2023] Open
Abstract
An increasing number of scientists working to raise agricultural productivity see the potential in the roots and the soil adjacent to them, together with a wealth of micro-organisms. The first mechanisms activated in the plant during any abiotic or biotic stress concern changes in the oxidative status of the plant. With this in mind, for the first time, an attempt was made to check whether the inoculation of seedlings of the model plant Medicago truncatula with rhizobacteria belonging to the genus Pseudomonas (P. brassicacearum KK5, P. corrugata KK7), Paenibacillus borealis KK4 and a symbiotic strain Sinorhizobium meliloti KK13 would change the oxidative status in the days following inoculation. Initially, an increase in H2O2 synthesis was observed, which led to an increase in the activity of antioxidant enzymes responsible for regulating hydrogen peroxide levels. The main enzyme involved in the reduction of H2O2 content in the roots was catalase. The observed changes indicate the possibility of using the applied rhizobacteria to induce processes related to plant resistance and thus to ensure protection against environmental stress factors. In the next stages, it seems reasonable to check whether the initial changes in the oxidative state affect the activation of other pathways related to plant immunity.
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DNA Methylation in
Ensifer
Species during Free-Living Growth and during Nitrogen-Fixing Symbiosis with
Medicago
spp. mSystems 2022; 7:e0109221. [PMID: 35089065 PMCID: PMC8725594 DOI: 10.1128/msystems.01092-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Nitrogen fixation by rhizobia in symbiosis with legumes is economically and ecologically important. The symbiosis can involve a complex bacterial transformation—terminal differentiation—that includes major shifts in the transcriptome and cell cycle.
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Kovacs S, Fodor L, Domonkos A, Ayaydin F, Laczi K, Rákhely G, Kalo P. Amino Acid Polymorphisms in the VHIID Conserved Motif of Nodulation Signaling Pathways 2 Distinctly Modulate Symbiotic Signaling and Nodule Morphogenesis in Medicago truncatula. FRONTIERS IN PLANT SCIENCE 2021; 12:709857. [PMID: 34966395 PMCID: PMC8711286 DOI: 10.3389/fpls.2021.709857] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 10/11/2021] [Indexed: 06/14/2023]
Abstract
Legumes establish an endosymbiotic association with nitrogen-fixing soil bacteria. Following the mutual recognition of the symbiotic partner, the infection process is controlled by the induction of the signaling pathway and subsequent activation of symbiosis-related host genes. One of the protein complexes regulating nitrogen-fixing root nodule symbiosis is formed by GRAS domain regulatory proteins Nodulation Signaling Pathways 1 and 2 (NSP1 and NSP2) that control the expression of several early nodulation genes. Here, we report on a novel point mutant allele (nsp2-6) affecting the function of the NSP2 gene and compared the mutant with the formerly identified nsp2-3 mutant. Both mutants carry a single amino acid substitution in the VHIID motif of the NSP2 protein. We found that the two mutant alleles show dissimilar root hair response to bacterial infection. Although the nsp2-3 mutant developed aberrant infection threads, rhizobia were able to colonize nodule cells in this mutant. The encoded NSP2 proteins of the nsp2-3 and the novel nsp2 mutants interact with NSP1 diversely and, as a consequence, the activation of early nodulin genes and nodule organogenesis are arrested in the new nsp2 allele. The novel mutant with amino acid substitution D244H in NSP2 shows similar defects in symbiotic responses as a formerly identified nsp2-2 mutant carrying a deletion in the NSP2 gene. Additionally, we found that rhizobial strains induce delayed nodule formation on the roots of the ns2-3 weak allele. Our study highlights the importance of a conserved Asp residue in the VHIID motif of NSP2 that is required for the formation of a functional NSP1-NSP2 signaling module. Furthermore, our results imply the involvement of NSP2 during differentiation of symbiotic nodule cells.
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Affiliation(s)
- Szilárd Kovacs
- Institute of Plant Biology, Biological Research Center, Eötvös Lóránd Research Network, Szeged, Hungary
| | - Lili Fodor
- Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Gödöllö, Hungary
| | - Agota Domonkos
- Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Gödöllö, Hungary
| | - Ferhan Ayaydin
- Hungarian Centre of Excellence for Molecular Medicine (HCEMM) Nonprofit Ltd., Szeged, Hungary
- Cellular Imaging Laboratory, Biological Research Center, Eötvös Lóránd Research Network, Szeged, Hungary
| | - Krisztián Laczi
- Institute of Plant Biology, Biological Research Center, Eötvös Lóránd Research Network, Szeged, Hungary
- Department of Biotechnology, University of Szeged, Szeged, Hungary
| | - Gábor Rákhely
- Department of Biotechnology, University of Szeged, Szeged, Hungary
- Institute of Biophysics, Biological Research Center, Eötvös Lóránd Research Network, Szeged, Hungary
| | - Péter Kalo
- Institute of Plant Biology, Biological Research Center, Eötvös Lóránd Research Network, Szeged, Hungary
- Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Gödöllö, Hungary
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5
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Zeng M, Wan B, Wang L, Chen Z, Lin Y, Ye W, Wang Y, Wang Y. Identification and characterization of L-type lectin receptor-like kinases involved in Glycine max-Phytophthora sojae interaction. PLANTA 2021; 254:128. [PMID: 34812941 DOI: 10.1007/s00425-021-03789-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 11/15/2021] [Indexed: 06/13/2023]
Abstract
MAIN CONCLUSION Soybean contains a group of 64 L-type lectin receptor-like kinases. Three LecRKs were involved in the interactions with Phytophthora sojae and Bradyrhizobium diazoefficiens. L-type lectin receptor-like kinases (LecRKs) comprise an important class of membrane-localized receptor-like kinases that are involved in plant adaptation. In this study, we performed an inventory analysis of LecRKs in Glycine max (soybean). In total, 64 GmLecRKs containing the canonical LecRK feature were identified. Phylogenetic analysis revealed that 48 GmLecRKs have close orthologs in Arabidopsis or Solanum lycopersicum, while 16 are likely present only in the leguminous plant species. Transcriptome analyses revealed that expressions of multiple GmLecRK genes are either induced or suppressed during infection by the soybean root rot pathogen Phytophthora sojae. In addition, overexpression of the three LecRKs (Glyma.17G085000, Glyma.05G041300 or Glyma.17G224600) in the soybean hairy roots enhanced resistance to P. sojae. Upon inoculation with Bradyrhizobium diazoefficiens, overexpression of Glyma.17G085000 in the soybean hairy roots does not significantly influence the nodulation, while overexpression of Glyma.05G041300 or Glyma.17G224600 slightly reduced the number and dry weight of nodules. This study highlights the importance of LecRKs in regulating plant-microbe interactions and provides new knowledge on the deployment of LecRKs to increase resistance in soybean.
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Affiliation(s)
- Mengzhu Zeng
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Bowen Wan
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Lei Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Zhiyuan Chen
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Yachun Lin
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Wenwu Ye
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, Jiangsu, China
| | - Yan Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China.
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu, China.
- The Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, Jiangsu, China.
| | - Yuanchao Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, Jiangsu, China
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Multiple sensors provide spatiotemporal oxygen regulation of gene expression in a Rhizobium-legume symbiosis. PLoS Genet 2021; 17:e1009099. [PMID: 33539353 PMCID: PMC7888657 DOI: 10.1371/journal.pgen.1009099] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 02/17/2021] [Accepted: 12/04/2020] [Indexed: 01/04/2023] Open
Abstract
Regulation by oxygen (O2) in rhizobia is essential for their symbioses with plants and involves multiple O2 sensing proteins. Three sensors exist in the pea microsymbiont Rhizobium leguminosarum Rlv3841: hFixL, FnrN and NifA. At low O2 concentrations (1%) hFixL signals via FxkR to induce expression of the FixK transcription factor, which activates transcription of downstream genes. These include fixNOQP, encoding the high-affinity cbb3-type terminal oxidase used in symbiosis. In free-living Rlv3841, the hFixL-FxkR-FixK pathway was active at 1% O2, and confocal microscopy showed hFixL-FxkR-FixK activity in the earliest stages of Rlv3841 differentiation in nodules (zones I and II). Work on Rlv3841 inside and outside nodules showed that the hFixL-FxkR-FixK pathway also induces transcription of fnrN at 1% O2 and in the earliest stages of Rlv3841 differentiation in nodules. We confirmed past findings suggesting a role for FnrN in fixNOQP expression. However, unlike hFixL-FxkR-FixK, Rlv3841 FnrN was only active in the near-anaerobic zones III and IV of pea nodules. Quantification of fixNOQP expression in nodules showed this was driven primarily by FnrN, with minimal direct hFixL-FxkR-FixK induction. Thus, FnrN is key for full symbiotic expression of fixNOQP. Without FnrN, nitrogen fixation was reduced by 85% in Rlv3841, while eliminating hFixL only reduced fixation by 25%. The hFixL-FxkR-FixK pathway effectively primes the O2 response by increasing fnrN expression in early differentiation (zones I-II). In zone III of mature nodules, near-anaerobic conditions activate FnrN, which induces fixNOQP transcription to the level required for wild-type nitrogen fixation activity. Modelling and transcriptional analysis indicates that the different O2 sensitivities of hFixL and FnrN lead to a nuanced spatiotemporal pattern of gene regulation in different nodule zones in response to changing O2 concentration. Multi-sensor O2 regulation is prevalent in rhizobia, suggesting the fine-tuned control this enables is common and maximizes the effectiveness of the symbioses. Rhizobia are soil bacteria that form a symbiosis with legume plants. In exchange for shelter from the plant, rhizobia provide nitrogen fertilizer, produced by nitrogen fixation. Fixation is catalysed by the nitrogenase enzyme, which is inactivated by oxygen. To prevent this, plants house rhizobia in root nodules, which create a low oxygen environment. However, rhizobia need oxygen, and must adapt to survive the low oxygen concentration in the nodule. Key to this is regulating their genes based on oxygen concentration. We studied one Rhizobium species which uses three different protein sensors of oxygen, each turning on at a different oxygen concentration. As the bacteria get deeper inside the plant nodule and the oxygen concentration drops, each sensor switches on in turn. Our results also show that the first sensor to turn on, hFixL, primes the second sensor, FnrN. This prepares the rhizobia for the core region of the nodule where oxygen concentration is lowest and most nitrogen fixation takes place. If both sensors are removed, the bacteria cannot fix nitrogen. Many rhizobia have several oxygen sensing proteins, so using multiple sensors is likely a common strategy enabling rhizobia to adapt to low oxygen precisely and in stages during symbiosis.
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7
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Walton JH, Kontra‐Kováts G, Green RT, Domonkos Á, Horváth B, Brear EM, Franceschetti M, Kaló P, Balk J. The Medicago truncatula Vacuolar iron Transporter-Like proteins VTL4 and VTL8 deliver iron to symbiotic bacteria at different stages of the infection process. THE NEW PHYTOLOGIST 2020; 228:651-666. [PMID: 32521047 PMCID: PMC7540006 DOI: 10.1111/nph.16735] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 05/27/2020] [Indexed: 05/28/2023]
Abstract
The symbiotic relationship between legumes and rhizobium bacteria in root nodules has a high demand for iron, and questions remain regarding which transporters are involved. Here, we characterize two nodule-specific Vacuolar iron Transporter-Like (VTL) proteins in Medicago truncatula. Localization of fluorescent fusion proteins and mutant studies were carried out to correlate with existing RNA-seq data showing differential expression of VTL4 and VTL8 during early and late infection, respectively. The vtl4 insertion lines showed decreased nitrogen fixation capacity associated with more immature nodules and less elongated bacteroids. A mutant line lacking the tandemly-arranged VTL4-VTL8 genes, named 13U, was unable to develop functional nodules and failed to fix nitrogen, which was almost fully restored by expression of VTL8 alone. Using a newly developed lux reporter to monitor iron status of the bacteroids, a moderate decrease in luminescence signal was observed in vtl4 mutant nodules and a strong decrease in 13U nodules. Iron transport capability of VTL4 and VTL8 was shown by yeast complementation. These data indicate that VTL8, the closest homologue of SEN1 in Lotus japonicus, is the main route for delivering iron to symbiotic rhizobia. We propose that a failure in iron protein maturation leads to early senescence of the bacteroids.
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Affiliation(s)
- Jennifer H. Walton
- Department of Biological ChemistryJohn Innes CentreNorwichNR4 7UHUK
- School of Biological SciencesUniversity of East AngliaNorwichNR4 7TJUK
| | | | - Robert T. Green
- Department of Biological ChemistryJohn Innes CentreNorwichNR4 7UHUK
| | - Ágota Domonkos
- Agricultural Biotechnology InstituteNARICGödöllő2100Hungary
| | | | - Ella M. Brear
- School of Life and Environmental SciencesThe University of SydneySydneyNSW2006Australia
| | | | - Péter Kaló
- Agricultural Biotechnology InstituteNARICGödöllő2100Hungary
- Institute of Plant BiologyBiological Research CentreSzeged6726Hungary
| | - Janneke Balk
- Department of Biological ChemistryJohn Innes CentreNorwichNR4 7UHUK
- School of Biological SciencesUniversity of East AngliaNorwichNR4 7TJUK
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8
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Burghardt LT, Trujillo DI, Epstein B, Tiffin P, Young ND. A Select and Resequence Approach Reveals Strain-Specific Effects of Medicago Nodule-Specific PLAT-Domain Genes. PLANT PHYSIOLOGY 2020; 182:463-471. [PMID: 31653715 PMCID: PMC6945875 DOI: 10.1104/pp.19.00831] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 10/07/2019] [Indexed: 05/23/2023]
Abstract
Genetic studies of legume symbiosis with nitrogen-fixing rhizobial bacteria have traditionally focused on nodule and nitrogen-fixation phenotypes when hosts are inoculated with a single rhizobial strain. These approaches overlook the potential effect of host genes on rhizobial fitness (i.e. how many rhizobia are released from host nodules) and strain-specific effects of host genes (i.e. genome × genome interactions). Using Medicago truncatula mutants in the recently described nodule-specific PLAT domain (NPD) gene family, we show how inoculating plants with a mixed inoculum of 68 rhizobial strains (Ensifer meliloti) via a select-and-resequence approach can be used to efficiently assay host mutants for strain-specific effects of late-acting host genes on interacting bacteria. The deletion of a single NPD gene (npd2) or all five members of the NPD gene family (npd1-5) differentially altered the frequency of rhizobial strains in nodules even though npd2 mutants had no visible nodule morphology or N-fixation phenotype. Also, npd1-5 nodules were less diverse and had larger populations of colony-forming rhizobia despite their smaller size. Lastly, NPD mutations disrupt a positive correlation between strain fitness and wild-type host biomass. These changes indicate that the effects of NPD proteins are strain dependent and that NPD family members are not redundant with regard to their effects on rhizobial strains. Association analyses of the rhizobial strains in the mixed inoculation indicate that rhizobial genes involved in chromosome segregation, cell division, GABA metabolism, efflux systems, and stress tolerance play an important role in the strain-specific effects of NPD genes.
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Affiliation(s)
- Liana T Burghardt
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota 55108
| | - Diana I Trujillo
- Department of Plant Pathology, University of Minnesota, St. Paul, Minnesota 55108
| | - Brendan Epstein
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota 55108
| | - Peter Tiffin
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota 55108
| | - Nevin D Young
- Department of Plant Pathology, University of Minnesota, St. Paul, Minnesota 55108
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Trněný O, Vlk D, Macková E, Matoušková M, Řepková J, Nedělník J, Hofbauer J, Vejražka K, Jakešová H, Jansa J, Piálek L, Knotová D. Allelic Variants for Candidate Nitrogen Fixation Genes Revealed by Sequencing in Red Clover ( Trifolium pratense L.). Int J Mol Sci 2019; 20:E5470. [PMID: 31684086 PMCID: PMC6862357 DOI: 10.3390/ijms20215470] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 10/25/2019] [Accepted: 10/30/2019] [Indexed: 02/06/2023] Open
Abstract
Plant-rhizobia symbiosis can activate key genes involved in regulating nodulation associated with biological nitrogen fixation (BNF). Although the general molecular basis of the BNF process is frequently studied, little is known about its intraspecific variability and the characteristics of its allelic variants. This study's main goals were to describe phenotypic and genotypic variation in the context of nitrogen fixation in red clover (Trifolium pretense L.) and identify variants in BNF candidate genes associated with BNF efficiency. Acetylene reduction assay validation was the criterion for selecting individual plants with particular BNF rates. Sequences in 86 key candidate genes were obtained by hybridization-based sequence capture target enrichment of plants with alternative phenotypes for nitrogen fixation. Two genes associated with BNF were identified: ethylene response factor required for nodule differentiation (EFD) and molybdate transporter 1 (MOT1). In addition, whole-genome population genotyping by double-digest restriction-site-associated sequencing (ddRADseq) was performed, and BNF was evaluated by the natural 15N abundance method. Polymorphisms associated with BNF and reflecting phenotype variability were identified. The genetic structure of plant accessions was not linked to BNF rate of measured plants. Knowledge of the genetic variation within BNF candidate genes and the characteristics of genetic variants will be beneficial in molecular diagnostics and breeding of red clover.
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Affiliation(s)
- Oldřich Trněný
- Agricultural Research, Ltd., Zahradní 1, 664 41 Troubsko, Czech Republic.
| | - David Vlk
- Department of Experimental Biology, Masaryk University, 625 00 Brno, Czech Republic.
| | - Eliška Macková
- Department of Experimental Biology, Masaryk University, 625 00 Brno, Czech Republic.
| | | | - Jana Řepková
- Department of Experimental Biology, Masaryk University, 625 00 Brno, Czech Republic.
| | - Jan Nedělník
- Agricultural Research, Ltd., Zahradní 1, 664 41 Troubsko, Czech Republic.
| | - Jan Hofbauer
- Agricultural Research, Ltd., Zahradní 1, 664 41 Troubsko, Czech Republic.
| | - Karel Vejražka
- Agricultural Research, Ltd., Zahradní 1, 664 41 Troubsko, Czech Republic.
| | - Hana Jakešová
- Red Clover and Grass Breeding, 724 47 Hladké Životice, Czech Republic.
| | - Jan Jansa
- Institute of Microbiology of the Academy of Sciences of the Czech Republic, 142 20 Prague, Czech Republic.
| | - Lubomír Piálek
- Department of Zoology, Faculty of Science, University of South Bohemia, 370 05 České Budějovice, Czech Republic.
| | - Daniela Knotová
- Research Institute for Fodder Crops, Ltd., 664 41 Troubsko, Czech Republic.
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10
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Das DR, Horváth B, Kundu A, Kaló P, DasGupta M. Functional conservation of CYCLOPS in crack entry legume Arachis hypogaea. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2019; 281:232-241. [PMID: 30824056 DOI: 10.1016/j.plantsci.2018.12.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 12/05/2018] [Accepted: 12/07/2018] [Indexed: 06/09/2023]
Abstract
Root nodule symbiosis in legumes is established following interaction of compatible rhizobia that activates an array of genes, commonly known as symbiotic-pathway, resulting in nodule development. In model legumes, bacterial entry mainly occurs through infection thread involving the expression of transcription factor CYCLOPS/IPD3. Here we show the functional analysis of AhCYCLOPS in Arachis hypogaea where bacteria invade roots through epidermal cracks. Exploiting significant cross-species domain conservation, trans-complementation experiments involving ectopic expression of AhCYCLOPS in transgenic hairy-roots of Medicago truncatula ipd3 mutants resulted in functional complementation of Medicago nodules. Moreover, native promoter of AhCYCLOPS was sufficient for this cross-species complementation irrespective of the different modes of infection of roots by rhizobia and nodule ontology. To unravel the role of AhCYCLOPS during 'crack-entry' nodulation in A. hypogaea, RNAi of AhCYCLOPS was performed which resulted in delayed nodule inception followed by drastic reduction in nodule number on transgenic hairy-roots. The infection zone of a significant number of RNAi nodules showed presence of infected cells with enlarged nucleus and rod shaped undifferentiated bacteria. Expression analysis showed downregulation of several nodulation responsible effectors endorsing the compromised condition of RNAi roots. Together, the results indicated that AhCYCLOPS plays an important role in A. hypogaea nodule development.
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Affiliation(s)
- Debapriya Rajlakshmi Das
- Department of Biochemistry, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700019, West Bengal, India
| | - Beatrix Horváth
- Agricultural Biotechnology Institute, NARIC, Szent-Györgyi Albert u. 4, Gödöllő, Hungary
| | - Anindya Kundu
- Department of Biochemistry, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700019, West Bengal, India
| | - Péter Kaló
- Agricultural Biotechnology Institute, NARIC, Szent-Györgyi Albert u. 4, Gödöllő, Hungary
| | - Maitrayee DasGupta
- Department of Biochemistry, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700019, West Bengal, India.
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11
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Pfeilmeier S, George J, Morel A, Roy S, Smoker M, Stransfeld L, Downie JA, Peeters N, Malone JG, Zipfel C. Expression of the Arabidopsis thaliana immune receptor EFR in Medicago truncatula reduces infection by a root pathogenic bacterium, but not nitrogen-fixing rhizobial symbiosis. PLANT BIOTECHNOLOGY JOURNAL 2019; 17:569-579. [PMID: 30120864 PMCID: PMC6381793 DOI: 10.1111/pbi.12999] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 07/11/2018] [Accepted: 08/13/2018] [Indexed: 05/12/2023]
Abstract
Interfamily transfer of plant pattern recognition receptors (PRRs) represents a promising biotechnological approach to engineer broad-spectrum, and potentially durable, disease resistance in crops. It is however unclear whether new recognition specificities to given pathogen-associated molecular patterns (PAMPs) affect the interaction of the recipient plant with beneficial microbes. To test this in a direct reductionist approach, we transferred the Brassicaceae-specific PRR ELONGATION FACTOR-THERMO UNSTABLE RECEPTOR (EFR), conferring recognition of the bacterial EF-Tu protein, from Arabidopsis thaliana to the legume Medicago truncatula. Constitutive EFR expression led to EFR accumulation and activation of immune responses upon treatment with the EF-Tu-derived elf18 peptide in leaves and roots. The interaction of M. truncatula with the bacterial symbiont Sinorhizobium meliloti is characterized by the formation of root nodules that fix atmospheric nitrogen. Although nodule numbers were slightly reduced at an early stage of the infection in EFR-Medicago when compared to control lines, nodulation was similar in all lines at later stages. Furthermore, nodule colonization by rhizobia, and nitrogen fixation were not compromised by EFR expression. Importantly, the M. truncatula lines expressing EFR were substantially more resistant to the root bacterial pathogen Ralstonia solanacearum. Our data suggest that the transfer of EFR to M. truncatula does not impede root nodule symbiosis, but has a positive impact on disease resistance against a bacterial pathogen. In addition, our results indicate that Rhizobium can either avoid PAMP recognition during the infection process, or is able to actively suppress immune signaling.
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Affiliation(s)
- Sebastian Pfeilmeier
- The Sainsbury LaboratoryNorwich Research ParkNorwichUK
- John Innes CentreNorwich Research ParkNorwichUK
- Present address:
Institute of MicrobiologyDepartment of BiologyETH ZurichZurich8093Switzerland
| | | | - Arry Morel
- INRALaboratoire des Interactions Plantes Micro‐organismes (LIPM)UMR441Castanet‐TolosanFrance
- CNRSLaboratoire des Interactions Plantes Micro‐organismes (LIPM)UMR2594Castanet‐TolosanFrance
| | - Sonali Roy
- John Innes CentreNorwich Research ParkNorwichUK
- Present address:
Noble Research InstituteArdmoreOKUSA
| | | | - Lena Stransfeld
- The Sainsbury LaboratoryNorwich Research ParkNorwichUK
- Institute of Plant and Microbial Biology & Zurich‐Basel Plant Science CenterUniversity of ZurichZurichSwitzerland
| | | | - Nemo Peeters
- INRALaboratoire des Interactions Plantes Micro‐organismes (LIPM)UMR441Castanet‐TolosanFrance
- CNRSLaboratoire des Interactions Plantes Micro‐organismes (LIPM)UMR2594Castanet‐TolosanFrance
| | - Jacob G. Malone
- John Innes CentreNorwich Research ParkNorwichUK
- School of Biological SciencesUniversity of East AngliaNorwichUK
| | - Cyril Zipfel
- The Sainsbury LaboratoryNorwich Research ParkNorwichUK
- Institute of Plant and Microbial Biology & Zurich‐Basel Plant Science CenterUniversity of ZurichZurichSwitzerland
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12
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Liu H, Sandal N, Andersen KR, James EK, Stougaard J, Kelly S, Kawaharada Y. A genetic screen for plant mutants with altered nodulation phenotypes in response to rhizobial glycan mutants. THE NEW PHYTOLOGIST 2018; 220:526-538. [PMID: 29959893 DOI: 10.1111/nph.15293] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Accepted: 05/24/2018] [Indexed: 05/08/2023]
Abstract
Nodule primordia induced by rhizobial glycan mutants often remain uninfected. To identify processes involved in infection and organogenesis we used forward genetics to identify plant genes involved in perception and responses to bacterial glycans. To dissect the mechanisms underlying the negative plant responses to the Mesorhizobium loti R7AexoU and ML001cep mutants, a screen for genetic suppressors of the nodulation phenotypes was performed on a chemically mutagenized Lotus population. Two mutant lines formed infected nitrogen-fixing pink nodules, while five mutant lines developed uninfected large white nodules, presumably altered in processes controlling organogenesis. Genetic mapping identified a mutation in the cytokinin receptor Lhk1 resulting in an alanine to valine substitution adjacent to a coiled-coil motif in the juxta-membrane region of LHK1. This results in a spontaneous nodulation phenotype and increased ethylene production. The allele was renamed snf5, and segregation studies of snf5 together with complementation studies suggest that snf5 is a gain-of-function allele. This forward genetic approach to investigate the role of glycans in the pathway synchronizing infection and organogenesis shows that a combination of plant and bacterial genetics opens new possibilities to study glycan responses in plants as well as identification of mutant alleles affecting nodule organogenesis.
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Affiliation(s)
- Huijun Liu
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10, DK-8000, Aarhus C, Denmark
| | - Niels Sandal
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10, DK-8000, Aarhus C, Denmark
| | - Kasper R Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10, DK-8000, Aarhus C, Denmark
| | - Euan K James
- The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Jens Stougaard
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10, DK-8000, Aarhus C, Denmark
| | - Simon Kelly
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10, DK-8000, Aarhus C, Denmark
| | - Yasuyuki Kawaharada
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10, DK-8000, Aarhus C, Denmark
- Department of Plant BioSciences, Faculty of Agriculture, Iwate University, 3-18-8-Ueda, Morioka, Iwate, Japan
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13
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Tsyganova AV, Tsyganov VE. Plant Genetic Control over Infection Thread Development during Legume-Rhizobium Symbiosis. Symbiosis 2018. [DOI: 10.5772/intechopen.70689] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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14
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Lang C, Smith LS, Haney CH, Long SR. Characterization of Novel Plant Symbiosis Mutants Using a New Multiple Gene-Expression Reporter Sinorhizobium meliloti Strain. FRONTIERS IN PLANT SCIENCE 2018; 9:76. [PMID: 29467773 PMCID: PMC5808326 DOI: 10.3389/fpls.2018.00076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 01/15/2018] [Indexed: 06/08/2023]
Abstract
The formation of nitrogen fixing root nodules by Medicago truncatula and Sinorhizobium meliloti requires communication between both organisms and coordinated differentiation of plant and bacterial cells. After an initial signal exchange, the bacteria invade the tissue of the growing nodule via plant-derived tubular structures, called infection threads. The bacteria are released from the infection threads into invasion-competent plant cells, where they differentiate into nitrogen-fixing bacteroids. Both organisms undergo dramatic transcriptional, metabolic and morphological changes during nodule development. To identify plant processes that are essential for the formation of nitrogen fixing nodules after nodule development has been initiated, large scale mutageneses have been conducted to discover underlying plant symbiosis genes. Such screens yield numerous uncharacterized plant lines with nitrogen fixation deficient nodules. In this study, we report construction of a S. meliloti strain carrying four distinct reporter constructs to reveal stages of root nodule development. The strain contains a constitutively expressed lacZ reporter construct; a PexoY-mTFP fusion that is expressed in infection threads but not in differentiated bacteroids; a PbacA-mcherry construct that is expressed in infection threads and during bacteroid differentiation; and a PnifH-uidA construct that is expressed during nitrogen fixation. We used this strain together with fluorescence microscopy to study nodule development over time in wild type nodules and to characterize eight plant mutants from a fast neutron bombardment screen. Based on the signal intensity and the localization patterns of the reporter genes, we grouped mutants with similar phenotypes and placed them in a developmental context.
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Affiliation(s)
| | | | | | - Sharon R. Long
- Gilbert Lab, Department of Biology, Stanford University, Stanford, CA, United States
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15
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Domonkos Á, Kovács S, Gombár A, Kiss E, Horváth B, Kováts GZ, Farkas A, Tóth MT, Ayaydin F, Bóka K, Fodor L, Ratet P, Kereszt A, Endre G, Kaló P. NAD1 Controls Defense-Like Responses in Medicago truncatula Symbiotic Nitrogen Fixing Nodules Following Rhizobial Colonization in a BacA-Independent Manner. Genes (Basel) 2017; 8:E387. [PMID: 29240711 PMCID: PMC5748705 DOI: 10.3390/genes8120387] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 12/04/2017] [Accepted: 12/11/2017] [Indexed: 11/19/2022] Open
Abstract
Legumes form endosymbiotic interaction with host compatible rhizobia, resulting in the development of nitrogen-fixing root nodules. Within symbiotic nodules, rhizobia are intracellularly accommodated in plant-derived membrane compartments, termed symbiosomes. In mature nodule, the massively colonized cells tolerate the existence of rhizobia without manifestation of visible defense responses, indicating the suppression of plant immunity in the nodule in the favur of the symbiotic partner. Medicago truncatulaDNF2 (defective in nitrogen fixation 2) and NAD1 (nodules with activated defense 1) genes are essential for the control of plant defense during the colonization of the nitrogen-fixing nodule and are required for bacteroid persistence. The previously identified nodule-specific NAD1 gene encodes a protein of unknown function. Herein, we present the analysis of novel NAD1 mutant alleles to better understand the function of NAD1 in the repression of immune responses in symbiotic nodules. By exploiting the advantage of plant double and rhizobial mutants defective in establishing nitrogen-fixing symbiotic interaction, we show that NAD1 functions following the release of rhizobia from the infection threads and colonization of nodule cells. The suppression of plant defense is self-dependent of the differentiation status of the rhizobia. The corresponding phenotype of nad1 and dnf2 mutants and the similarity in the induction of defense-associated genes in both mutants suggest that NAD1 and DNF2 operate close together in the same pathway controlling defense responses in symbiotic nodules.
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Affiliation(s)
- Ágota Domonkos
- National Agricultural and Innovation Center, Agricultural Biotechnology Institute, 2100 Gödöllő, Hungary.
| | - Szilárd Kovács
- Institute of Plant Biology, Biological Research Center, 6726 Szeged, Hungary.
- Institute of Genetics, Biological Research Center, 6726 Szeged, Hungary.
| | - Anikó Gombár
- National Agricultural and Innovation Center, Agricultural Biotechnology Institute, 2100 Gödöllő, Hungary.
| | - Ernő Kiss
- Institute of Genetics, Biological Research Center, 6726 Szeged, Hungary.
| | - Beatrix Horváth
- National Agricultural and Innovation Center, Agricultural Biotechnology Institute, 2100 Gödöllő, Hungary.
| | - Gyöngyi Z Kováts
- National Agricultural and Innovation Center, Agricultural Biotechnology Institute, 2100 Gödöllő, Hungary.
| | - Attila Farkas
- Institute of Plant Biology, Biological Research Center, 6726 Szeged, Hungary.
| | - Mónika T Tóth
- National Agricultural and Innovation Center, Agricultural Biotechnology Institute, 2100 Gödöllő, Hungary.
| | - Ferhan Ayaydin
- Cellular Imaging Laboratory, Biological Research Center, 6726 Szeged, Hungary.
| | - Károly Bóka
- Department of Plant Anatomy, Eötvös Loránd University, 1117 Budapest, Hungary.
| | - Lili Fodor
- National Agricultural and Innovation Center, Agricultural Biotechnology Institute, 2100 Gödöllő, Hungary.
| | - Pascal Ratet
- Institute of Plant Sciences Paris-Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université Evry, Université Paris-Saclay, Bâtiment 630, 91405 Orsay, France.
- Institute of Plant Sciences Paris-Saclay IPS2, Paris Diderot, Sorbonne Paris-Cité, Bâtiment 630, 91405 Orsay, France.
| | - Attila Kereszt
- Institute of Plant Biology, Biological Research Center, 6726 Szeged, Hungary.
| | - Gabriella Endre
- Institute of Plant Biology, Biological Research Center, 6726 Szeged, Hungary.
- Institute of Genetics, Biological Research Center, 6726 Szeged, Hungary.
| | - Péter Kaló
- National Agricultural and Innovation Center, Agricultural Biotechnology Institute, 2100 Gödöllő, Hungary.
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16
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Plant signalling in symbiosis and immunity. Nature 2017; 543:328-336. [PMID: 28300100 DOI: 10.1038/nature22009] [Citation(s) in RCA: 395] [Impact Index Per Article: 56.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 01/13/2017] [Indexed: 12/12/2022]
Abstract
Plants encounter a myriad of microorganisms, particularly at the root-soil interface, that can invade with detrimental or beneficial outcomes. Prevalent beneficial associations between plants and microorganisms include those that promote plant growth by facilitating the acquisition of limiting nutrients such as nitrogen and phosphorus. But while promoting such symbiotic relationships, plants must restrict the formation of pathogenic associations. Achieving this balance requires the perception of potential invading microorganisms through the signals that they produce, followed by the activation of either symbiotic responses that promote microbial colonization or immune responses that limit it.
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17
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Robledo M, Peregrina A, Millán V, García-Tomsig NI, Torres-Quesada O, Mateos PF, Becker A, Jiménez-Zurdo JI. A conserved α-proteobacterial small RNA contributes to osmoadaptation and symbiotic efficiency of rhizobia on legume roots. Environ Microbiol 2017; 19:2661-2680. [PMID: 28401641 DOI: 10.1111/1462-2920.13757] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 04/05/2017] [Accepted: 04/05/2017] [Indexed: 02/02/2023]
Abstract
Small non-coding RNAs (sRNAs) are expected to have pivotal roles in the adaptive responses underlying symbiosis of nitrogen-fixing rhizobia with legumes. Here, we provide primary insights into the function and activity mechanism of the Sinorhizobium meliloti trans-sRNA NfeR1 (Nodule Formation Efficiency RNA). Northern blot probing and transcription tracking with fluorescent promoter-reporter fusions unveiled high nfeR1 expression in response to salt stress and throughout the symbiotic interaction. The strength and differential regulation of nfeR1 transcription are conferred by a motif, which is conserved in nfeR1 promoter regions in α-proteobacteria. NfeR1 loss-of-function compromised osmoadaptation of free-living bacteria, whilst causing misregulation of salt-responsive genes related to stress adaptation, osmolytes catabolism and membrane trafficking. Nodulation tests revealed that lack of NfeR1 affected competitiveness, infectivity, nodule development and symbiotic efficiency of S. meliloti on alfalfa roots. Comparative computer predictions and a genetic reporter assay evidenced a redundant role of three identical NfeR1 unpaired anti Shine-Dalgarno motifs for targeting and downregulation of translation of multiple mRNAs from transporter genes. Our data provide genetic evidence of the hyperosmotic conditions of the endosymbiotic compartments. NfeR1-mediated gene regulation in response to this cue could contribute to coordinate nutrient uptake with the metabolic reprogramming concomitant to symbiotic transitions.
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Affiliation(s)
- Marta Robledo
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
| | - Alexandra Peregrina
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
| | - Vicenta Millán
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
| | - Natalia I García-Tomsig
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
| | - Omar Torres-Quesada
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
| | - Pedro F Mateos
- Departamento de Microbiología y Genética and CIALE, Edificio Departamental, Campus Miguel de Unamuno, Universidad de Salamanca, 37007 Salamanca, Spain
| | - Anke Becker
- LOEWE Center for Synthetic Microbiology and Faculty of Biology, Philipps-Universität Marburg, 35043 Marburg, Germany
| | - José I Jiménez-Zurdo
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
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18
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Curtin SJ, Tiffin P, Guhlin J, Trujillo DI, Burghart LT, Atkins P, Baltes NJ, Denny R, Voytas DF, Stupar RM, Young ND. Validating Genome-Wide Association Candidates Controlling Quantitative Variation in Nodulation. PLANT PHYSIOLOGY 2017; 173:921-931. [PMID: 28057894 PMCID: PMC5291020 DOI: 10.1104/pp.16.01923] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 01/04/2017] [Indexed: 05/22/2023]
Abstract
Genome-wide association (GWA) studies offer the opportunity to identify genes that contribute to naturally occurring variation in quantitative traits. However, GWA relies exclusively on statistical association, so functional validation is necessary to make strong claims about gene function. We used a combination of gene-disruption platforms (Tnt1 retrotransposons, hairpin RNA-interference constructs, and CRISPR/Cas9 nucleases) together with randomized, well-replicated experiments to evaluate the function of genes that an earlier GWA study in Medicago truncatula had identified as candidates contributing to variation in the symbiosis between legumes and rhizobia. We evaluated ten candidate genes found in six clusters of strongly associated single nucleotide polymorphisms, selected on the basis of their strength of statistical association, proximity to annotated gene models, and root or nodule expression. We found statistically significant effects on nodule production for three candidate genes, each validated in two independent mutants. Annotated functions of these three genes suggest their contributions to quantitative variation in nodule production occur through processes not previously connected to nodulation, including phosphorous supply and salicylic acid-related defense response. These results demonstrate the utility of GWA combined with reverse mutagenesis technologies to discover and validate genes contributing to naturally occurring variation in quantitative traits. The results highlight the potential for GWA to complement forward genetics in identifying the genetic basis of ecologically and economically important traits.
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Affiliation(s)
- Shaun J Curtin
- Department of Plant Pathology (S.J.C., R.D., N.D.Y.) and Department of Plant Biology (P.T., J.G., D.T., L.B., N.D.Y.), University of Minnesota, St. Paul, Minnesota 55108
- Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (P.A., N.J.B., D.F.V.); and
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108 (R.M.S.)
| | - Peter Tiffin
- Department of Plant Pathology (S.J.C., R.D., N.D.Y.) and Department of Plant Biology (P.T., J.G., D.T., L.B., N.D.Y.), University of Minnesota, St. Paul, Minnesota 55108
- Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (P.A., N.J.B., D.F.V.); and
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108 (R.M.S.)
| | - Joseph Guhlin
- Department of Plant Pathology (S.J.C., R.D., N.D.Y.) and Department of Plant Biology (P.T., J.G., D.T., L.B., N.D.Y.), University of Minnesota, St. Paul, Minnesota 55108
- Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (P.A., N.J.B., D.F.V.); and
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108 (R.M.S.)
| | - Diana I Trujillo
- Department of Plant Pathology (S.J.C., R.D., N.D.Y.) and Department of Plant Biology (P.T., J.G., D.T., L.B., N.D.Y.), University of Minnesota, St. Paul, Minnesota 55108
- Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (P.A., N.J.B., D.F.V.); and
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108 (R.M.S.)
| | - Liana T Burghart
- Department of Plant Pathology (S.J.C., R.D., N.D.Y.) and Department of Plant Biology (P.T., J.G., D.T., L.B., N.D.Y.), University of Minnesota, St. Paul, Minnesota 55108
- Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (P.A., N.J.B., D.F.V.); and
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108 (R.M.S.)
| | - Paul Atkins
- Department of Plant Pathology (S.J.C., R.D., N.D.Y.) and Department of Plant Biology (P.T., J.G., D.T., L.B., N.D.Y.), University of Minnesota, St. Paul, Minnesota 55108
- Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (P.A., N.J.B., D.F.V.); and
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108 (R.M.S.)
| | - Nicholas J Baltes
- Department of Plant Pathology (S.J.C., R.D., N.D.Y.) and Department of Plant Biology (P.T., J.G., D.T., L.B., N.D.Y.), University of Minnesota, St. Paul, Minnesota 55108
- Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (P.A., N.J.B., D.F.V.); and
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108 (R.M.S.)
| | - Roxanne Denny
- Department of Plant Pathology (S.J.C., R.D., N.D.Y.) and Department of Plant Biology (P.T., J.G., D.T., L.B., N.D.Y.), University of Minnesota, St. Paul, Minnesota 55108
- Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (P.A., N.J.B., D.F.V.); and
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108 (R.M.S.)
| | - Daniel F Voytas
- Department of Plant Pathology (S.J.C., R.D., N.D.Y.) and Department of Plant Biology (P.T., J.G., D.T., L.B., N.D.Y.), University of Minnesota, St. Paul, Minnesota 55108
- Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (P.A., N.J.B., D.F.V.); and
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108 (R.M.S.)
| | - Robert M Stupar
- Department of Plant Pathology (S.J.C., R.D., N.D.Y.) and Department of Plant Biology (P.T., J.G., D.T., L.B., N.D.Y.), University of Minnesota, St. Paul, Minnesota 55108
- Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (P.A., N.J.B., D.F.V.); and
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108 (R.M.S.)
| | - Nevin D Young
- Department of Plant Pathology (S.J.C., R.D., N.D.Y.) and Department of Plant Biology (P.T., J.G., D.T., L.B., N.D.Y.), University of Minnesota, St. Paul, Minnesota 55108;
- Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (P.A., N.J.B., D.F.V.); and
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108 (R.M.S.)
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19
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Larrainzar E, Wienkoop S. A Proteomic View on the Role of Legume Symbiotic Interactions. FRONTIERS IN PLANT SCIENCE 2017; 8:1267. [PMID: 28769967 PMCID: PMC5513976 DOI: 10.3389/fpls.2017.01267] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 07/05/2017] [Indexed: 05/04/2023]
Abstract
Legume plants are key elements in sustainable agriculture and represent a significant source of plant-based protein for humans and animal feed worldwide. One specific feature of the family is the ability to establish nitrogen-fixing symbiosis with Rhizobium bacteria. Additionally, like most vascular flowering plants, legumes are able to form a mutualistic endosymbiosis with arbuscular mycorrhizal (AM) fungi. These beneficial associations can enhance the plant resistance to biotic and abiotic stresses. Understanding how symbiotic interactions influence and increase plant stress tolerance are relevant questions toward maintaining crop yield and food safety in the scope of climate change. Proteomics offers numerous tools for the identification of proteins involved in such responses, allowing the study of sub-cellular localization and turnover regulation, as well as the discovery of post-translational modifications (PTMs). The current work reviews the progress made during the last decades in the field of proteomics applied to the study of the legume-Rhizobium and -AM symbioses, and highlights their influence on the plant responses to pathogens and abiotic stresses. We further discuss future perspectives and new experimental approaches that are likely to have a significant impact on the field including peptidomics, mass spectrometric imaging, and quantitative proteomics.
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Affiliation(s)
- Estíbaliz Larrainzar
- Department of Environmental Sciences, Universidad Pública de NavarraPamplona, Spain
- *Correspondence: Estíbaliz Larrainzar
| | - Stefanie Wienkoop
- Department of Ecogenomics and Systems Biology, University of ViennaVienna, Austria
- Stefanie Wienkoop
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20
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Wang C, Yu H, Luo L, Duan L, Cai L, He X, Wen J, Mysore KS, Li G, Xiao A, Duanmu D, Cao Y, Hong Z, Zhang Z. NODULES WITH ACTIVATED DEFENSE 1 is required for maintenance of rhizobial endosymbiosis in Medicago truncatula. THE NEW PHYTOLOGIST 2016; 212:176-91. [PMID: 27245091 DOI: 10.1111/nph.14017] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 04/13/2016] [Indexed: 05/27/2023]
Abstract
The symbiotic interaction between legume plants and rhizobia results in the formation of root nodules, in which symbiotic plant cells host and harbor thousands of nitrogen-fixing rhizobia. Here, a Medicago truncatula nodules with activated defense 1 (nad1) mutant was identified using reverse genetics methods. The mutant phenotype was characterized using cell and molecular biology approaches. An RNA-sequencing technique was used to analyze the transcriptomic reprogramming of nad1 mutant nodules. In the nad1 mutant plants, rhizobial infection and propagation in infection threads are normal, whereas rhizobia and their symbiotic plant cells become necrotic immediately after rhizobia are released from infection threads into symbiotic cells of nodules. Defense-associated responses were detected in nad1 nodules. NAD1 is specifically present in root nodule symbiosis plants with the exception of Morus notabilis, and the transcript is highly induced in nodules. NAD1 encodes a small uncharacterized protein with two predicted transmembrane helices and is localized at the endoplasmic reticulum. Our data demonstrate a positive role for NAD1 in the maintenance of rhizobial endosymbiosis during nodulation.
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Affiliation(s)
- Chao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Haixiang Yu
- State Key Laboratory of Agricultural Microbiology, College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Li Luo
- Shanghai Key Lab of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai, 200444, China
| | - Liujian Duan
- State Key Laboratory of Agricultural Microbiology, College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Liuyang Cai
- National Key Laboratory of Crop Genetic Improvement, College of Informatics, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xinxing He
- State Key Laboratory of Agricultural Microbiology, College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jiangqi Wen
- Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA
| | - Kirankumar S Mysore
- Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA
| | - Guoliang Li
- National Key Laboratory of Crop Genetic Improvement, College of Informatics, Huazhong Agricultural University, Wuhan, 430070, China
| | - Aifang Xiao
- State Key Laboratory of Agricultural Microbiology, College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Deqiang Duanmu
- State Key Laboratory of Agricultural Microbiology, College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yangrong Cao
- State Key Laboratory of Agricultural Microbiology, College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Zonglie Hong
- Department of Plant, Soil and Entomological Sciences and Program of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Moscow, ID, 83844, USA
| | - Zhongming Zhang
- State Key Laboratory of Agricultural Microbiology, College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, 430070, China
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Zhukov VA, Rychagov TS, Fedorina JV, Pinaev AG, Andronov EE, Borisov AY, Tikhonovich IA. Features of expression of the PsSst1 and PsIgn1 genes in nodules of pea (Pisum sativum L.) symbiotic mutants. RUSS J GENET+ 2016. [DOI: 10.1134/s1022795416040128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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22
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Arbuscular mycorrhiza development in pea (Pisum sativum L.) mutants impaired in five early nodulation genes including putative orthologs of NSP1 and NSP2. Symbiosis 2016. [DOI: 10.1007/s13199-016-0382-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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23
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Kang Y, Li M, Sinharoy S, Verdier J. A Snapshot of Functional Genetic Studies in Medicago truncatula. FRONTIERS IN PLANT SCIENCE 2016; 7:1175. [PMID: 27555857 PMCID: PMC4977297 DOI: 10.3389/fpls.2016.01175] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Accepted: 07/21/2016] [Indexed: 05/21/2023]
Abstract
In the current context of food security, increase of plant protein production in a sustainable manner represents one of the major challenges of agronomic research, which could be partially resolved by increased cultivation of legume crops. Medicago truncatula is now a well-established model for legume genomic and genetic studies. With the establishment of genomics tools and mutant populations in M. truncatula, it has become an important resource to answer some of the basic biological questions related to plant development and stress tolerance. This review has an objective to overview a decade of genetic studies in this model plant from generation of mutant populations to nowadays. To date, the three biological fields, which have been extensively studied in M. truncatula, are the symbiotic nitrogen fixation, the seed development, and the abiotic stress tolerance, due to their significant agronomic impacts. In this review, we summarize functional genetic studies related to these three major biological fields. We integrated analyses of a nearly exhaustive list of genes into their biological contexts in order to provide an overview of the forefront research advances in this important legume model plant.
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Affiliation(s)
- Yun Kang
- Plant Biology Division, The Samuel Roberts Noble FoundationArdmore, OK, USA
| | - Minguye Li
- University of Chinese Academy of SciencesBeijing, China
- Shanghai Plant Stress Center, Shanghai Institutes of Biological Sciences, Chinese Academy of SciencesShanghai, China
| | - Senjuti Sinharoy
- Department of Biotechnology, University of CalcuttaCalcutta, India
| | - Jerome Verdier
- Shanghai Plant Stress Center, Shanghai Institutes of Biological Sciences, Chinese Academy of SciencesShanghai, China
- *Correspondence: Jerome Verdier
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Rey T, Laporte P, Bonhomme M, Jardinaud MF, Huguet S, Balzergue S, Dumas B, Niebel A, Jacquet C. MtNF-YA1, A Central Transcriptional Regulator of Symbiotic Nodule Development, Is Also a Determinant of Medicago truncatula Susceptibility toward a Root Pathogen. FRONTIERS IN PLANT SCIENCE 2016; 7:1837. [PMID: 27994614 PMCID: PMC5137509 DOI: 10.3389/fpls.2016.01837] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 11/22/2016] [Indexed: 05/20/2023]
Abstract
Plant NF-Y transcription factors control a wide array of biological functions enabling appropriate reproductive and developmental processes as well as adaptation to various abiotic and biotic environments. In Medicago truncatula, MtNF-YA1 was previously identified as a key determinant for nodule development and establishment of rhizobial symbiosis. Here, we highlight a new role for this protein in compatibility to Aphanomyces euteiches, a root pathogenic oomycete. The Mtnf-ya1-1 mutant plants showed better survival rate, reduced symptoms, and increased development of their root apparatus as compared to their wild-type (WT) background A17. MtNF-YA-1 was specifically up-regulated by A. euteiches in F83005.5, a highly susceptible natural accession of M. truncatula while transcript level remained stable in A17, which is partially resistant. The role of MtNF-YA1 in F83005.5 susceptibility was further documented by reducing MtNF-YA1 expression either by overexpression of the miR169q, a microRNA targeting MtNF-YA1, or by RNAi approaches leading to a strong enhancement in the resistance of this susceptible line. Comparative analysis of the transcriptome of WT and Mtnf-ya1-1 led to the identification of 1509 differentially expressed genes. Among those, almost 36 defense-related genes were constitutively expressed in Mtnf-ya1-1, while 20 genes linked to hormonal pathways were repressed. In summary, we revealed an unexpected dual role for this symbiotic transcription factor as a key player in the compatibility mechanisms to a pathogen.
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Affiliation(s)
- Thomas Rey
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, UPSCastanet Tolosan, France
- *Correspondence: Thomas Rey,
| | - Philippe Laporte
- Institut National de la Recherche Agronomique, Laboratoire des Interactions Plantes-Microorganismes, UMR441Castanet-Tolosan, France
- Centre National de la Recherche Scientifique, Laboratoire des Interactions Plantes-Microorganismes, UMR2594Castanet-Tolosan, France
| | - Maxime Bonhomme
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, UPSCastanet Tolosan, France
| | - Marie-Françoise Jardinaud
- Institut National de la Recherche Agronomique, Laboratoire des Interactions Plantes-Microorganismes, UMR441Castanet-Tolosan, France
- Centre National de la Recherche Scientifique, Laboratoire des Interactions Plantes-Microorganismes, UMR2594Castanet-Tolosan, France
| | - Stéphanie Huguet
- POPS Transcriptomic Platform – Institute of Plant Sciences Paris-Saclay IPS2, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université Paris-Sud, Université d’Évry Val-d’Essonne, Université Paris Diderot, Sorbonne Paris-Cite, Universite Paris-SaclayOrsay, France
| | - Sandrine Balzergue
- POPS Transcriptomic Platform – Institute of Plant Sciences Paris-Saclay IPS2, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université Paris-Sud, Université d’Évry Val-d’Essonne, Université Paris Diderot, Sorbonne Paris-Cite, Universite Paris-SaclayOrsay, France
| | - Bernard Dumas
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, UPSCastanet Tolosan, France
| | - Andreas Niebel
- Institut National de la Recherche Agronomique, Laboratoire des Interactions Plantes-Microorganismes, UMR441Castanet-Tolosan, France
- Centre National de la Recherche Scientifique, Laboratoire des Interactions Plantes-Microorganismes, UMR2594Castanet-Tolosan, France
| | - Christophe Jacquet
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, UPSCastanet Tolosan, France
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Loss of the nodule-specific cysteine rich peptide, NCR169, abolishes symbiotic nitrogen fixation in the Medicago truncatula dnf7 mutant. Proc Natl Acad Sci U S A 2015; 112:15232-7. [PMID: 26401023 DOI: 10.1073/pnas.1500777112] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Host compatible rhizobia induce the formation of legume root nodules, symbiotic organs within which intracellular bacteria are present in plant-derived membrane compartments termed symbiosomes. In Medicago truncatula nodules, the Sinorhizobium microsymbionts undergo an irreversible differentiation process leading to the development of elongated polyploid noncultivable nitrogen fixing bacteroids that convert atmospheric dinitrogen into ammonia. This terminal differentiation is directed by the host plant and involves hundreds of nodule specific cysteine-rich peptides (NCRs). Except for certain in vitro activities of cationic peptides, the functional roles of individual NCR peptides in planta are not known. In this study, we demonstrate that the inability of M. truncatula dnf7 mutants to fix nitrogen is due to inactivation of a single NCR peptide, NCR169. In the absence of NCR169, bacterial differentiation was impaired and was associated with early senescence of the symbiotic cells. Introduction of the NCR169 gene into the dnf7-2/NCR169 deletion mutant restored symbiotic nitrogen fixation. Replacement of any of the cysteine residues in the NCR169 peptide with serine rendered it incapable of complementation, demonstrating an absolute requirement for all cysteines in planta. NCR169 was induced in the cell layers in which bacteroid elongation was most pronounced, and high expression persisted throughout the nitrogen-fixing nodule zone. Our results provide evidence for an essential role of NCR169 in the differentiation and persistence of nitrogen fixing bacteroids in M. truncatula.
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26
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Lang C, Long SR. Transcriptomic Analysis of Sinorhizobium meliloti and Medicago truncatula Symbiosis Using Nitrogen Fixation-Deficient Nodules. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:856-868. [PMID: 25844838 DOI: 10.1094/mpmi-12-14-0407-r] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The bacterium Sinorhizobium meliloti interacts symbiotically with legume plant hosts such as Medicago truncatula to form nitrogen-fixing root nodules. During symbiosis, plant and bacterial cells differentiate in a coordinated manner, resulting in specialized plant cells that contain nitrogen-fixing bacteroids. Both plant and bacterial genes are required at each developmental stage of symbiosis. We analyzed gene expression in nodules formed by wild-type bacteria on six plant mutants with defects in nitrogen fixation. We observed differential expression of 482 S. meliloti genes with functions in cell envelope homeostasis, cell division, stress response, energy metabolism, and nitrogen fixation. We simultaneously analyzed gene expression in M. truncatula and observed differential regulation of host processes that may trigger bacteroid differentiation and control bacterial infection. Our analyses of developmentally arrested plant mutants indicate that plants use distinct means to control bacterial infection during early and late symbiotic stages.
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Affiliation(s)
- Claus Lang
- Department of Biology, Stanford University, Stanford, CA 94305-5020, U.S.A
| | - Sharon R Long
- Department of Biology, Stanford University, Stanford, CA 94305-5020, U.S.A
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van Zeijl A, Op den Camp RHM, Deinum EE, Charnikhova T, Franssen H, Op den Camp HJM, Bouwmeester H, Kohlen W, Bisseling T, Geurts R. Rhizobium Lipo-chitooligosaccharide Signaling Triggers Accumulation of Cytokinins in Medicago truncatula Roots. MOLECULAR PLANT 2015; 8:1213-26. [PMID: 25804975 DOI: 10.1016/j.molp.2015.03.010] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 03/12/2015] [Accepted: 03/15/2015] [Indexed: 05/20/2023]
Abstract
Legume rhizobium symbiosis is initiated upon perception of bacterial secreted lipo-chitooligosaccharides (LCOs). Perception of these signals by the plant initiates a signaling cascade that leads to nodule formation. Several studies have implicated a function for cytokinin in this process. However, whether cytokinin accumulation and subsequent signaling are an integral part of rhizobium LCO signaling remains elusive. Here, we show that cytokinin signaling is required for the majority of transcriptional changes induced by rhizobium LCOs. In addition, we demonstrate that several cytokinins accumulate in the root susceptible zone 3 h after rhizobium LCO application, including the biologically most active cytokinins, trans-zeatin and isopentenyl adenine. These responses are dependent on calcium- and calmodulin-dependent protein kinase (CCaMK), a key protein in rhizobial LCO-induced signaling. Analysis of the ethylene-insensitive Mtein2/Mtsickle mutant showed that LCO-induced cytokinin accumulation is negatively regulated by ethylene. Together with transcriptional induction of ethylene biosynthesis genes, it suggests a feedback loop negatively regulating LCO signaling and subsequent cytokinin accumulation. We argue that cytokinin accumulation is a key step in the pathway leading to nodule organogenesis and that this is tightly controlled by feedback loops.
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Affiliation(s)
- Arjan van Zeijl
- Department of Plant Sciences, Laboratory of Molecular Biology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Rik H M Op den Camp
- Department of Plant Sciences, Laboratory of Molecular Biology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Eva E Deinum
- Department of Plant Sciences, Laboratory of Molecular Biology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; Department of Systems Biophysics, FOM institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Tatsiana Charnikhova
- Department of Plant Sciences, Laboratory of Plant Physiology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Henk Franssen
- Department of Plant Sciences, Laboratory of Molecular Biology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Huub J M Op den Camp
- Department of Microbiology, IWWR, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Harro Bouwmeester
- Department of Plant Sciences, Laboratory of Plant Physiology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Wouter Kohlen
- Department of Plant Sciences, Laboratory of Molecular Biology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Ton Bisseling
- Department of Plant Sciences, Laboratory of Molecular Biology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; College of Science, King Saud University, Post Office Box 2455, Riyadh 11451, Saudi Arabia
| | - René Geurts
- Department of Plant Sciences, Laboratory of Molecular Biology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
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28
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Berrabah F, Ratet P, Gourion B. Multiple steps control immunity during the intracellular accommodation of rhizobia. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:1977-85. [PMID: 25682610 PMCID: PMC4378630 DOI: 10.1093/jxb/eru545] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 12/15/2014] [Accepted: 12/16/2014] [Indexed: 05/20/2023]
Abstract
Medicago truncatula belongs to the legume family and forms symbiotic associations with nitrogen fixing bacteria, the rhizobia. During these interactions, the plants develop root nodules in which bacteria invade the plant cells and fix nitrogen for the benefit of the plant. Despite massive infection, legume nodules do not develop visible defence reactions, suggesting a special immune status of these organs. Some factors influencing rhizobium maintenance within the plant cells have been previously identified, such as the M. truncatula NCR peptides whose toxic effects are reduced by the bacterial protein BacA. In addition, DNF2, SymCRK, and RSD are M. truncatula genes required to avoid rhizobial death within the symbiotic cells. DNF2 and SymCRK are essential to prevent defence-like reactions in nodules after bacteria internalization into the symbiotic cells. Herein, we used a combination of genetics, histology and molecular biology approaches to investigate the relationship between the factors preventing bacterial death in the nodule cells. We show that the RSD gene is also required to repress plant defences in nodules. Upon inoculation with the bacA mutant, defence responses are observed only in the dnf2 mutant and not in the symCRK and rsd mutants. In addition, our data suggest that lack of nitrogen fixation by the bacterial partner triggers bacterial death in nodule cells after bacteroid differentiation. Together our data indicate that, after internalization, at least four independent mechanisms prevent bacterial death in the plant cell. These mechanisms involve successively: DNF2, BacA, SymCRK/RSD and bacterial ability to fix nitrogen.
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Affiliation(s)
- Fathi Berrabah
- Institut des Sciences du Végétal, CNRS, Saclay Plant Sciences, Avenue de la Terrasse, 91198 Gif sur Yvette, France
| | - Pascal Ratet
- Institut des Sciences du Végétal, CNRS, Saclay Plant Sciences, Avenue de la Terrasse, 91198 Gif sur Yvette, France
| | - Benjamin Gourion
- Institut des Sciences du Végétal, CNRS, Saclay Plant Sciences, Avenue de la Terrasse, 91198 Gif sur Yvette, France
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29
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Ahsan N, Stevenson SE. Proteomic mapping for legume nodule organogenesis. Proteomics 2014; 14:153-4. [PMID: 24395658 DOI: 10.1002/pmic.201300552] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 12/16/2013] [Indexed: 11/08/2022]
Abstract
While genetic screens have identified mutants of the model legume Lotus japonicus that can nodulate in the absence of rhizobia, the lack of a proteome map is a major hindrance to understanding the functional protein networks associated with this nodulation process. In this issue of Proteomics, Dam et al. (Proteomics 2014, 14, 230-240) developed 2D gel-based reference maps of nodules and roots of Lotus and a spontaneous nodule formation mutant (snf1). Comparative proteomic analysis of roots and two developmental stages of nodules provide useful insights into tissue-specific mechanisms underlying nodule organogenesis. Additionally, a comparison of interspecies nodule proteomes displays that overlapping and individual mechanisms are associated with legume nodulation.
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Affiliation(s)
- Nagib Ahsan
- Department of Biochemistry and Interdisciplinary Plant Group, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO, USA
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