1
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Klepa MS, diCenzo GC, Hungria M. Comparative genomic analysis of Bradyrhizobium strains with natural variability in the efficiency of nitrogen fixation, competitiveness, and adaptation to stressful edaphoclimatic conditions. Microbiol Spectr 2024; 12:e0026024. [PMID: 38842312 PMCID: PMC11218460 DOI: 10.1128/spectrum.00260-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Accepted: 05/01/2024] [Indexed: 06/07/2024] Open
Abstract
Bradyrhizobium is known for fixing atmospheric nitrogen in symbiosis with agronomically important crops. This study focused on two groups of strains, each containing eight natural variants of the parental strains, Bradyrhizobium japonicum SEMIA 586 (=CNPSo 17) or Bradyrhizobium diazoefficiens SEMIA 566 (=CNPSo 10). CNPSo 17 and CNPSo 10 were used as commercial inoculants for soybean crops in Brazil at the beginning of the crop expansion in the southern region in the 1960s-1970s. Variants derived from these parental strains were obtained in the late 1980s through a strain selection program aimed at identifying elite strains adapted to a new cropping frontier in the central-western Cerrado region, with a higher capacity of biological nitrogen fixation (BNF) and competitiveness. Here, we aimed to detect genetic variations possibly related to BNF, competitiveness for nodule occupancy, and adaptation to the stressful conditions of the Brazilian Cerrado soils. High-quality genome assemblies were produced for all strains. The core genome phylogeny revealed that strains of each group are closely related, as confirmed by high average nucleotide identity values. However, variants accumulated divergences resulting from horizontal gene transfer, genomic rearrangements, and nucleotide polymorphisms. The B. japonicum group presented a larger pangenome and a higher number of nucleotide polymorphisms than the B. diazoefficiens group, possibly due to its longer adaptation time to the Cerrado soil. Interestingly, five strains of the B. japonicum group carry two plasmids. The genetic variability found in both groups is discussed considering the observed differences in their BNF capacity, competitiveness for nodule occupancy, and environmental adaptation.IMPORTANCEToday, Brazil is a global leader in the study and use of biological nitrogen fixation with soybean crops. As Brazilian soils are naturally void of soybean-compatible bradyrhizobia, strain selection programs were established, starting with foreign isolates. Selection searched for adaptation to the local edaphoclimatic conditions, higher efficiency of nitrogen fixation, and strong competitiveness for nodule occupancy. We analyzed the genomes of two parental strains of Bradyrhizobium japonicum and Bradyrhizobium diazoefficiens and eight variant strains derived from each parental strain. We detected two plasmids in five strains and several genetic differences that might be related to adaptation to the stressful conditions of the soils of the Brazilian Cerrado biome. We also detected genetic variations in specific regions that may impact symbiotic nitrogen fixation. Our analysis contributes to new insights into the evolution of Bradyrhizobium, and some of the identified differences may be applied as genetic markers to assist strain selection programs.
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Affiliation(s)
- Milena Serenato Klepa
- Soil Biotechnology Laboratory, Embrapa Soja, Londrina, Paraná, Brazil
- CNPq, Brasília, Brazil
| | | | - Mariangela Hungria
- Soil Biotechnology Laboratory, Embrapa Soja, Londrina, Paraná, Brazil
- CNPq, Brasília, Brazil
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2
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Knights HE, Ramachandran VK, Jorrin B, Ledermann R, Parsons JD, Aroney STN, Poole PS. Rhizobium determinants of rhizosphere persistence and root colonization. THE ISME JOURNAL 2024; 18:wrae072. [PMID: 38690786 PMCID: PMC11103875 DOI: 10.1093/ismejo/wrae072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 04/16/2024] [Accepted: 04/23/2024] [Indexed: 05/03/2024]
Abstract
Bacterial persistence in the rhizosphere and colonization of root niches are critical for the establishment of many beneficial plant-bacteria interactions including those between Rhizobium leguminosarum and its host legumes. Despite this, most studies on R. leguminosarum have focused on its symbiotic lifestyle as an endosymbiont in root nodules. Here, we use random barcode transposon sequencing to assay gene contributions of R. leguminosarum during competitive growth in the rhizosphere and colonization of various plant species. This facilitated the identification of 189 genes commonly required for growth in diverse plant rhizospheres, mutation of 111 of which also affected subsequent root colonization (rhizosphere progressive), and a further 119 genes necessary for colonization. Common determinants reveal a need to synthesize essential compounds (amino acids, ribonucleotides, and cofactors), adapt metabolic function, respond to external stimuli, and withstand various stresses (such as changes in osmolarity). Additionally, chemotaxis and flagella-mediated motility are prerequisites for root colonization. Many genes showed plant-specific dependencies highlighting significant adaptation to different plant species. This work provides a greater understanding of factors promoting rhizosphere fitness and root colonization in plant-beneficial bacteria, facilitating their exploitation for agricultural benefit.
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Affiliation(s)
- Hayley E Knights
- Department of Biology, University of Oxford, Oxford OX1 3RB, United Kingdom
| | | | - Beatriz Jorrin
- Department of Biology, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Raphael Ledermann
- Department of Biology, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Jack D Parsons
- Department of Biology, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Samuel T N Aroney
- Department of Biology, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Philip S Poole
- Department of Biology, University of Oxford, Oxford OX1 3RB, United Kingdom
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3
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Granada Agudelo M, Ruiz B, Capela D, Remigi P. The role of microbial interactions on rhizobial fitness. FRONTIERS IN PLANT SCIENCE 2023; 14:1277262. [PMID: 37877089 PMCID: PMC10591227 DOI: 10.3389/fpls.2023.1277262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 09/22/2023] [Indexed: 10/26/2023]
Abstract
Rhizobia are soil bacteria that can establish a nitrogen-fixing symbiosis with legume plants. As horizontally transmitted symbionts, the life cycle of rhizobia includes a free-living phase in the soil and a plant-associated symbiotic phase. Throughout this life cycle, rhizobia are exposed to a myriad of other microorganisms that interact with them, modulating their fitness and symbiotic performance. In this review, we describe the diversity of interactions between rhizobia and other microorganisms that can occur in the rhizosphere, during the initiation of nodulation, and within nodules. Some of these rhizobia-microbe interactions are indirect, and occur when the presence of some microbes modifies plant physiology in a way that feeds back on rhizobial fitness. We further describe how these interactions can impose significant selective pressures on rhizobia and modify their evolutionary trajectories. More extensive investigations on the eco-evolutionary dynamics of rhizobia in complex biotic environments will likely reveal fascinating new aspects of this well-studied symbiotic interaction and provide critical knowledge for future agronomical applications.
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Affiliation(s)
- Margarita Granada Agudelo
- Laboratoire des Interactions Plantes Microbes Environnement (LIPME), Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Bryan Ruiz
- Laboratoire des Interactions Plantes Microbes Environnement (LIPME), Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Delphine Capela
- Laboratoire des Interactions Plantes Microbes Environnement (LIPME), Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Philippe Remigi
- Laboratoire des Interactions Plantes Microbes Environnement (LIPME), Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
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4
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Young JPW, Jorrin B, Moeskjær S, James EK. Rhizobium brockwellii sp. nov., Rhizobium johnstonii sp. nov. and Rhizobium beringeri sp. nov., three genospecies within the Rhizobium leguminosarum species complex. Int J Syst Evol Microbiol 2023; 73. [PMID: 37486744 DOI: 10.1099/ijsem.0.005979] [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: 07/25/2023] Open
Abstract
Genomic evidence indicates that the
Rhizobium leguminosarum
species complex comprises multiple distinct species, perhaps 18 or more. Of the five earliest genospecies (gs) to be described, only two have formal names: R. leguminosarum sensu stricto (gsE) and
Rhizobium ruizarguesonis
(gsC). Here, we provide formal descriptions and names for the other three genospecies, based on the publicly available genome sequences for multiple strains of each species: Rhizobium brockwellii sp. nov. (gsA, 37 strains, type strain CC275eT=LMG 6122T = ICMP 2163T=NZP 561T = PDDCC 2163T=HAMBI 13T), Rhizobium johnstonii sp. nov. (gsB, 54 strains, type strain 3841T = LMG 32736T=DSM 114642T) and Rhizobium beringeri sp. nov. (gsD, 8 strains, type strain SM51T = LMG 32895T = DSM 115206T). Each species forms a well-supported clade in a phylogeny based on 120 concatenated core genes. All strains have average nucleotide identity (ANI) above 96 % with the relevant type strain and below 96 % with all other type strains. Each species is characterised by a number of genes that are absent or rare in other species.
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Affiliation(s)
- J Peter W Young
- Department of Biology, University of York, York YO10 5DD, UK
| | - Beatriz Jorrin
- Department of Biology, University of Oxford, Oxford OX1 3RB, UK
| | - Sara Moeskjær
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Euan K James
- Ecological Sciences, The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK
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5
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Lepetit M, Brouquisse R. Control of the rhizobium-legume symbiosis by the plant nitrogen demand is tightly integrated at the whole plant level and requires inter-organ systemic signaling. FRONTIERS IN PLANT SCIENCE 2023; 14:1114840. [PMID: 36968361 PMCID: PMC10033964 DOI: 10.3389/fpls.2023.1114840] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 02/16/2023] [Indexed: 06/18/2023]
Abstract
Symbiotic nodules formed on legume roots with rhizobia fix atmospheric N2. Bacteria reduce N2 to NH4 + that is assimilated into amino acids by the plant. In return, the plant provides photosynthates to fuel the symbiotic nitrogen fixation. Symbiosis is tightly adjusted to the whole plant nutritional demand and to the plant photosynthetic capacities, but regulatory circuits behind this control remain poorly understood. The use of split-root systems combined with biochemical, physiological, metabolomic, transcriptomic, and genetic approaches revealed that multiple pathways are acting in parallel. Systemic signaling mechanisms of the plant N demand are required for the control of nodule organogenesis, mature nodule functioning, and nodule senescence. N-satiety/N-deficit systemic signaling correlates with rapid variations of the nodules' sugar levels, tuning symbiosis by C resources allocation. These mechanisms are responsible for the adjustment of plant symbiotic capacities to the mineral N resources. On the one hand, if mineral N can satisfy the plant N demand, nodule formation is inhibited, and nodule senescence is activated. On the other hand, local conditions (abiotic stresses) may impair symbiotic activity resulting in plant N limitation. In these conditions, systemic signaling may compensate the N deficit by stimulating symbiotic root N foraging. In the past decade, several molecular components of the systemic signaling pathways controlling nodule formation have been identified, but a major challenge remains, that is, to understand their specificity as compared to the mechanisms of non-symbiotic plants that control root development and how they contribute to the whole plant phenotypes. Less is known about the control of mature nodule development and functioning by N and C nutritional status of the plant, but a hypothetical model involving the sucrose allocation to the nodule as a systemic signaling process, the oxidative pentose phosphate pathway, and the redox status as potential effectors of this signaling is emerging. This work highlights the importance of organism integration in plant biology.
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Xavier GR, Jesus EDC, Dias A, Coelho MRR, Molina YC, Rumjanek NG. Contribution of Biofertilizers to Pulse Crops: From Single-Strain Inoculants to New Technologies Based on Microbiomes Strategies. PLANTS (BASEL, SWITZERLAND) 2023; 12:954. [PMID: 36840302 PMCID: PMC9962295 DOI: 10.3390/plants12040954] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/14/2023] [Accepted: 02/16/2023] [Indexed: 06/18/2023]
Abstract
Pulses provide distinct health benefits due to their low fat content and high protein and fiber contents. Their grain production reaches approximately 93,210 × 103 tons per year. Pulses benefit from the symbiosis with atmospheric N2-fixing bacteria, which increases productivity and reduces the need for N fertilizers, thus contributing to mitigation of environmental impact mitigation. Additionally, the root region harbors a rich microbial community with multiple traits related to plant growth promotion, such as nutrient increase and tolerance enhancement to abiotic or biotic stresses. We reviewed the eight most common pulses accounting for almost 90% of world production: common beans, chickpeas, peas, cowpeas, mung beans, lentils, broad beans, and pigeon peas. We focused on updated information considering both single-rhizobial inoculation and co-inoculation with plant growth-promoting rhizobacteria. We found approximately 80 microbial taxa with PGPR traits, mainly Bacillus sp., B. subtilis, Pseudomonas sp., P. fluorescens, and arbuscular mycorrhizal fungi, and that contributed to improve plant growth and yield under different conditions. In addition, new data on root, nodule, rhizosphere, and seed microbiomes point to strategies that can be used to design new generations of biofertilizers, highlighting the importance of microorganisms for productive pulse systems.
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Affiliation(s)
| | | | - Anelise Dias
- Departamento de Fitotecnia, Instituto de Agronomia, Universidade Federal Rural do Rio de Janeiro, UFRRJ, Rodovia BR-465, Km 7, Seropédica 23890-000, RJ, Brazil
| | | | - Yulimar Castro Molina
- Programa de Pós-graduação em Microbiologia Agrícola, Universidade Federal de Lavras, UFLA, Trevo Rotatório Professor Edmir Sá Santos, Lavras 37203-202, MG, Brazil
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7
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Bartoli C, Boivin S, Marta M, Gris C, Gasciolli V, Gaston M, Auriac MC, Debellé F, Cottret L, Carlier A, Masson-Boivin C, Lepetit M, Lefebvre B. Rhizobium leguminosarum symbiovar viciae strains are natural wheat endophytes that can stimulate root development. Environ Microbiol 2022; 24:5509-5523. [PMID: 35920038 DOI: 10.1111/1462-2920.16148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 07/21/2022] [Accepted: 07/22/2022] [Indexed: 11/26/2022]
Abstract
Although rhizobia that establish a nitrogen-fixing symbiosis with legumes are also known to promote growth in non-legumes, studies on rhizobial associations with wheat roots are scarce. We searched for Rhizobium leguminosarum symbiovar viciae (Rlv) strains naturally competent to endophytically colonize wheat roots. We isolated 20 strains from surface-sterilized wheat roots, and found a low diversity of Rlv compared to that observed in the Rlv species complex. We tested the ability of a subset of these Rlv for wheat root colonization when co-inoculated with other Rlv. Only a few strains, including those isolated from wheat roots, and one strain isolated from pea nodules, were efficient in colonizing roots in co-inoculation conditions, while all the strains tested in single strain inoculation conditions were found to colonize the surface and interior of roots. Furthermore, Rlv strains isolated from wheat roots were able to stimulate root development and early arbuscular mycorrhizal fungi colonization. These responses were strain and host genotype dependent. Our results suggest that wheat can be an alternative host for Rlv; nevertheless, there is a strong competition between Rlv strains for wheat root colonization. In addition, we showed that Rlv are endophytic wheat root bacteria with potential ability to modify wheat development.
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Affiliation(s)
- Claudia Bartoli
- IGEPP, INRAE, Institut Agro, Univ Rennes, 35653, Le Rheu, France.,LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Stéphane Boivin
- Laboratoire des Symbioses Tropicales et Méditerranéennes INRAE, IRD, CIRAD, University of Montpellier, Montpellier SupAgro Montpellier, France
| | - Marchetti Marta
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Carine Gris
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | | | - Mégane Gaston
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Marie-Christine Auriac
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France.,FRAIB-TRI Imaging Platform Facilities, Université de Toulouse, CNRS, 24 chemin de Borderouge, Castanet-Tolosan, France
| | - Frédéric Debellé
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Ludovic Cottret
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Aurélien Carlier
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | | | - Marc Lepetit
- Laboratoire des Symbioses Tropicales et Méditerranéennes INRAE, IRD, CIRAD, University of Montpellier, Montpellier SupAgro Montpellier, France.,Institut Sophia Agrobiotech INRAE, CNRS, University Côte d'azur, Sophia Antipolis, France
| | - Benoit Lefebvre
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
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8
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Hsouna J, Gritli T, Ilahi H, Ellouze W, Mansouri M, Chihaoui SA, Bouhnik O, Missbah El Idrissi M, Abdelmoumen H, Wipf D, Courty PE, Bekki A, Tambong JT, Mnasri B. Genotypic and symbiotic diversity studies of rhizobia nodulating Acacia saligna in Tunisia reveal two novel symbiovars within the Rhizobium leguminosarum complex and Bradyrhizobium. Syst Appl Microbiol 2022; 45:126343. [PMID: 35759954 DOI: 10.1016/j.syapm.2022.126343] [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: 02/21/2022] [Revised: 05/08/2022] [Accepted: 06/12/2022] [Indexed: 11/15/2022]
Abstract
Acacia saligna is an invasive alien species that has the ability to establish symbiotic relationships with rhizobia. In the present study, genotypic and symbiotic diversity of native rhizobia associated with A. saligna in Tunisia were studied. A total of 100 bacterial strains were selected and three different ribotypes were identified based on rrs PCR-RFLP analysis. Sequence analyses of rrs and four housekeeping genes (recA, atpD, gyrB and glnII) assigned 30 isolates to four putative new lineages and a single strain to Sinorhizobium meliloti. Thirteen slow-growing isolates representing the most dominant IGS (intergenic spacer) profile clustered distinctly from known rhizobia species within Bradyrhizobium with the closest related species being Bradyrhizobium shewense and Bradyrhizobium niftali, which had 95.17% and 95.1% sequence identity, respectively. Two slow-growing isolates, 1AS28L and 5AS6L, had B. frederekii as their closest species with a sequence identity of 95.2%, an indication that these strains could constitute a new lineage. Strains 1AS14I, 1AS12I and 6AS6 clustered distinctly from known rhizobia species but within the Rhizobium leguminosarum complex (Rlc) with the most closely related species being Rhizobium indicum with 96.3% sequence identity. Similarly, the remaining 11 strains showed 96.9 % and 97.2% similarity values with R. changzhiense and R. indicum, respectively. Based on nodC and nodA phylogenies and cross inoculation tests, these 14 strains of Rlc species clearly diverged from strains of Sinorhizobium and Rlc symbiovars, and formed a new symbiovar for which the name sv. "salignae" is proposed. Bacterial strains isolated in this study that were taxonomically assigned to Bradyrhizobium harbored different symbiotic genes and the data suggested a new symbiovar, for which sv. "cyanophyllae" is proposed. Isolates formed effective nodules on A. saligna.
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Affiliation(s)
- Jihed Hsouna
- Laboratory of Legumes and Sustainable Agroecosystems, Centre of Biotechnology of Borj-Cédria, BP 901 Hammam-lif 2050, Tunisia
| | - Takwa Gritli
- Laboratory of Legumes and Sustainable Agroecosystems, Centre of Biotechnology of Borj-Cédria, BP 901 Hammam-lif 2050, Tunisia
| | - Houda Ilahi
- Laboratory of Legumes and Sustainable Agroecosystems, Centre of Biotechnology of Borj-Cédria, BP 901 Hammam-lif 2050, Tunisia
| | - Walid Ellouze
- Agriculture and Agri-Food Canada, 4902 Victoria Avenue North, Vineland Station, Ontario L0R 2E0, Canada.
| | - Maroua Mansouri
- Laboratory of Legumes and Sustainable Agroecosystems, Centre of Biotechnology of Borj-Cédria, BP 901 Hammam-lif 2050, Tunisia
| | - Saif-Allah Chihaoui
- Laboratory of Legumes and Sustainable Agroecosystems, Centre of Biotechnology of Borj-Cédria, BP 901 Hammam-lif 2050, Tunisia
| | - Omar Bouhnik
- Faculty of Sciences, Centre de Biotechnologies Végétale et Microbienne, Biodiversité et Environnement, Mohammed V University, Rabat, Morocco
| | - Mustapha Missbah El Idrissi
- Faculty of Sciences, Centre de Biotechnologies Végétale et Microbienne, Biodiversité et Environnement, Mohammed V University, Rabat, Morocco
| | - Hanaa Abdelmoumen
- Faculty of Sciences, Centre de Biotechnologies Végétale et Microbienne, Biodiversité et Environnement, Mohammed V University, Rabat, Morocco
| | - Daniel Wipf
- Agroécologie, Institut Agro Dijon, CNRS, Univ. Bourgogne, INRAE, Univ. Bourgogne Franche-Comté, F-21000 Dijon, France
| | - Pierre Emmanuel Courty
- Agroécologie, Institut Agro Dijon, CNRS, Univ. Bourgogne, INRAE, Univ. Bourgogne Franche-Comté, F-21000 Dijon, France
| | - Abdelkader Bekki
- Laboratory of Rhizobia Biotechnology and Plant Breeding, University Oran1, Es Senia 31000, Algeria
| | - James T Tambong
- Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, Ontario K1A 0C6, Canada
| | - Bacem Mnasri
- Laboratory of Legumes and Sustainable Agroecosystems, Centre of Biotechnology of Borj-Cédria, BP 901 Hammam-lif 2050, Tunisia.
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Rajnovic I, Ramírez-Bahena MH, Kajic S, Igual JM, Peix Á, Velázquez E, Sikora S. Rhizobium croatiense sp. nov. and Rhizobium redzepovicii sp. nov., two new species isolated from nodules of Phaseolus vulgaris in Croatia. Syst Appl Microbiol 2022; 45:126317. [DOI: 10.1016/j.syapm.2022.126317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/01/2022] [Accepted: 03/02/2022] [Indexed: 10/18/2022]
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10
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Youseif SH, Abd El-Megeed FH, Abdelaal AS, Ageez A, Martínez-Romero E. Plant-microbe-microbe interactions influence the faba bean nodule colonization by diverse endophytic bacteria. FEMS Microbiol Ecol 2021; 97:6381688. [PMID: 34610117 DOI: 10.1093/femsec/fiab138] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 09/30/2021] [Indexed: 11/14/2022] Open
Abstract
Legume root nodules harbor rhizobia and other non-nodulating endophytes known as nodule-associated bacteria (NAB) whose role in the legume symbiosis is still unknown. We analysed the genetic diversity of 34 NAB isolates obtained from the root nodules of faba bean grown under various soil conditions in Egypt using 16S rRNA and concatenated sequences of three housekeeping genes. All isolates were identified as members of the family Enterobacteriaceae belonging to the genera Klebsiella, Enterobacter and Raoultella. We identified nine enterobacterial genospecies, most of which have not been previously reported as NAB. All isolated strains harbored nifH gene sequences and most of them possessed plant growth-promoting (PGP) traits. Upon co-inoculation with an N2 fixing rhizobium (Rlv NGB-FR128), two strains (Enterobacter sichanensis NGB-FR97 and Klebsiella variicola NGB-FR116) significantly increased nodulation, growth and N-uptake of faba bean plants over the single treatments or the uninoculated control. The presence of these enterobacteria in nodules was significantly affected by the host plant genotype, symbiotic rhizobium genotype and endophyte genotype, indicating that the nodule colonization process is regulated by plant-microbe-microbe interactions. This study emphasizes the importance of nodule-associated enterobacteria and suggests their potential role in improving the effectiveness of rhizobial inoculants.
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Affiliation(s)
- Sameh H Youseif
- Department of Microbial Genetic Resources, National Gene Bank, Agricultural Research Center (ARC), Giza 12619, Egypt
| | - Fayrouz H Abd El-Megeed
- Department of Microbial Genetic Resources, National Gene Bank, Agricultural Research Center (ARC), Giza 12619, Egypt
| | - Ali S Abdelaal
- Department of Genetics, Faculty of Agriculture, Damietta University, Damietta 34517, Egypt
| | - Amr Ageez
- Agricultural Genetic Engineering Research Institute, Agricultural Research Center (ARC), Giza 12619, Egypt.,Faculty of Biotechnology, MSA University, 6th of October City 12451, Egypt
| | - Esperanza Martínez-Romero
- Programa de Ecología Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, Mexico
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11
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Bellabarba A, Bacci G, Decorosi F, Aun E, Azzarello E, Remm M, Giovannetti L, Viti C, Mengoni A, Pini F. Competitiveness for Nodule Colonization in Sinorhizobium meliloti: Combined In Vitro-Tagged Strain Competition and Genome-Wide Association Analysis. mSystems 2021. [PMID: 34313466 DOI: 10.1101/2020.09.15.298034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023] Open
Abstract
Associations between leguminous plants and symbiotic nitrogen-fixing rhizobia are a classic example of mutualism between a eukaryotic host and a specific group of prokaryotic microbes. Although this symbiosis is in part species specific, different rhizobial strains may colonize the same nodule. Some rhizobial strains are commonly known as better competitors than others, but detailed analyses that aim to predict rhizobial competitive abilities based on genomes are still scarce. Here, we performed a bacterial genome-wide association (GWAS) analysis to define the genomic determinants related to the competitive capabilities in the model rhizobial species Sinorhizobium meliloti. For this, 13 tester strains were green fluorescent protein (GFP) tagged and assayed versus 3 red fluorescent protein (RFP)-tagged reference competitor strains (Rm1021, AK83, and BL225C) in a Medicago sativa nodule occupancy test. Competition data and strain genomic sequences were employed to build a model for GWAS based on k-mers. Among the k-mers with the highest scores, 51 k-mers mapped on the genomes of four strains showing the highest competition phenotypes (>60% single strain nodule occupancy; GR4, KH35c, KH46, and SM11) versus BL225C. These k-mers were mainly located on the symbiosis-related megaplasmid pSymA, specifically on genes coding for transporters, proteins involved in the biosynthesis of cofactors, and proteins related to metabolism (e.g., fatty acids). The same analysis was performed considering the sum of single and mixed nodules obtained in the competition assays versus BL225C, retrieving k-mers mapped on the genes previously found and on vir genes. Therefore, the competition abilities seem to be linked to multiple genetic determinants and comprise several cellular components. IMPORTANCE Decoding the competitive pattern that occurs in the rhizosphere is challenging in the study of bacterial social interaction strategies. To date, the single-gene approach has mainly been used to uncover the bases of nodulation, but there is still a knowledge gap regarding the main features that a priori characterize rhizobial strains able to outcompete indigenous rhizobia. Therefore, tracking down which traits make different rhizobial strains able to win the competition for plant infection over other indigenous rhizobia will improve the strain selection process and, consequently, plant yield in sustainable agricultural production systems. We proved that a k-mer-based GWAS approach can efficiently identify the competition determinants of a panel of strains previously analyzed for their plant tissue occupancy using double fluorescent labeling. The reported strategy will be useful for detailed studies on the genomic aspects of the evolution of bacterial symbiosis and for an extensive evaluation of rhizobial inoculants.
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Affiliation(s)
- Agnese Bellabarba
- Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
- Genexpress Laboratory, Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
| | - Giovanni Bacci
- Department of Biology, University of Florencegrid.8404.8, Sesto Fiorentino, Italy
| | - Francesca Decorosi
- Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
- Genexpress Laboratory, Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
| | - Erki Aun
- Department of Bioinformatics, Institute of Molecular and Cell Biology, University of Tartugrid.10939.32, Tartu, Estonia
| | - Elisa Azzarello
- Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
| | - Maido Remm
- Department of Bioinformatics, Institute of Molecular and Cell Biology, University of Tartugrid.10939.32, Tartu, Estonia
| | - Luciana Giovannetti
- Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
- Genexpress Laboratory, Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
| | - Carlo Viti
- Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
- Genexpress Laboratory, Department of Agronomy, Food, Environmental and Forestry (DAGRI), University of Florencegrid.8404.8, Sesto Fiorentino, Italy
| | - Alessio Mengoni
- Department of Biology, University of Florencegrid.8404.8, Sesto Fiorentino, Italy
| | - Francesco Pini
- Department of Biology, University of Bari Aldo Morogrid.7644.1, Bari, Italy
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12
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Mendoza-Suárez M, Andersen SU, Poole PS, Sánchez-Cañizares C. Competition, Nodule Occupancy, and Persistence of Inoculant Strains: Key Factors in the Rhizobium-Legume Symbioses. FRONTIERS IN PLANT SCIENCE 2021; 12:690567. [PMID: 34489993 PMCID: PMC8416774 DOI: 10.3389/fpls.2021.690567] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Accepted: 07/19/2021] [Indexed: 05/06/2023]
Abstract
Biological nitrogen fixation by Rhizobium-legume symbioses represents an environmentally friendly and inexpensive alternative to the use of chemical nitrogen fertilizers in legume crops. Rhizobial inoculants, applied frequently as biofertilizers, play an important role in sustainable agriculture. However, inoculants often fail to compete for nodule occupancy against native rhizobia with inferior nitrogen-fixing abilities, resulting in low yields. Strains with excellent performance under controlled conditions are typically selected as inoculants, but the rates of nodule occupancy compared to native strains are rarely investigated. Lack of persistence in the field after agricultural cycles, usually due to the transfer of symbiotic genes from the inoculant strain to naturalized populations, also limits the suitability of commercial inoculants. When rhizobial inoculants are based on native strains with a high nitrogen fixation ability, they often have superior performance in the field due to their genetic adaptations to the local environment. Therefore, knowledge from laboratory studies assessing competition and understanding how diverse strains of rhizobia behave, together with assays done under field conditions, may allow us to exploit the effectiveness of native populations selected as elite strains and to breed specific host cultivar-rhizobial strain combinations. Here, we review current knowledge at the molecular level on competition for nodulation and the advances in molecular tools for assessing competitiveness. We then describe ongoing approaches for inoculant development based on native strains and emphasize future perspectives and applications using a multidisciplinary approach to ensure optimal performance of both symbiotic partners.
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Affiliation(s)
| | - Stig U. Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Philip S. Poole
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
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13
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Fields B, Moffat EK, Harrison E, Andersen SU, Young JPW, Friman VP. Genetic variation is associated with differences in facilitative and competitive interactions in the Rhizobium leguminosarum species complex. Environ Microbiol 2021; 24:3463-3485. [PMID: 34398510 DOI: 10.1111/1462-2920.15720] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 07/08/2021] [Accepted: 08/10/2021] [Indexed: 12/01/2022]
Abstract
Competitive and facilitative interactions influence bacterial community composition, diversity and functioning. However, the role of genetic diversity for determining interactions between coexisting strains of the same, or closely related, species remains poorly understood. Here, we investigated the type (facilitative/inhibitory) and potential underlying mechanisms of pairwise interactions between 24 genetically diverse bacterial strains belonging to three genospecies (gsA,C,E) of the Rhizobium leguminosarum species complex. Interactions were determined indirectly, based on secreted compounds in cell-free supernatants, and directly, as growth inhibition in cocultures. We found supernatants mediated both facilitative and inhibitory interactions that varied greatly between strains and genospecies. Overall, gsE strains indirectly suppressed growth of gsA strains, while their own growth was facilitated by other genospecies' supernatants. Similar genospecies-level patterns were observed in direct competition, where gsA showed the highest susceptibility and gsE the highest inhibition capacity. At the genetic level, increased gsA susceptibility was associated with a non-random distribution of quorum sensing and secondary metabolite genes across genospecies. Together, our results suggest that genetic variation is associated with facilitative and competitive interactions, which could be important ecological mechanisms explaining R. leguminosarum diversity.
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Affiliation(s)
| | - Emma K Moffat
- Department of Biology, University of York, York, UK.,Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Ellie Harrison
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Stig U Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
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14
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Competitiveness for Nodule Colonization in Sinorhizobium meliloti: Combined In Vitro-Tagged Strain Competition and Genome-Wide Association Analysis. mSystems 2021; 6:e0055021. [PMID: 34313466 PMCID: PMC8407117 DOI: 10.1128/msystems.00550-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Associations between leguminous plants and symbiotic nitrogen-fixing rhizobia are a classic example of mutualism between a eukaryotic host and a specific group of prokaryotic microbes. Although this symbiosis is in part species specific, different rhizobial strains may colonize the same nodule. Some rhizobial strains are commonly known as better competitors than others, but detailed analyses that aim to predict rhizobial competitive abilities based on genomes are still scarce. Here, we performed a bacterial genome-wide association (GWAS) analysis to define the genomic determinants related to the competitive capabilities in the model rhizobial species Sinorhizobium meliloti. For this, 13 tester strains were green fluorescent protein (GFP) tagged and assayed versus 3 red fluorescent protein (RFP)-tagged reference competitor strains (Rm1021, AK83, and BL225C) in a Medicago sativa nodule occupancy test. Competition data and strain genomic sequences were employed to build a model for GWAS based on k-mers. Among the k-mers with the highest scores, 51 k-mers mapped on the genomes of four strains showing the highest competition phenotypes (>60% single strain nodule occupancy; GR4, KH35c, KH46, and SM11) versus BL225C. These k-mers were mainly located on the symbiosis-related megaplasmid pSymA, specifically on genes coding for transporters, proteins involved in the biosynthesis of cofactors, and proteins related to metabolism (e.g., fatty acids). The same analysis was performed considering the sum of single and mixed nodules obtained in the competition assays versus BL225C, retrieving k-mers mapped on the genes previously found and on vir genes. Therefore, the competition abilities seem to be linked to multiple genetic determinants and comprise several cellular components. IMPORTANCE Decoding the competitive pattern that occurs in the rhizosphere is challenging in the study of bacterial social interaction strategies. To date, the single-gene approach has mainly been used to uncover the bases of nodulation, but there is still a knowledge gap regarding the main features that a priori characterize rhizobial strains able to outcompete indigenous rhizobia. Therefore, tracking down which traits make different rhizobial strains able to win the competition for plant infection over other indigenous rhizobia will improve the strain selection process and, consequently, plant yield in sustainable agricultural production systems. We proved that a k-mer-based GWAS approach can efficiently identify the competition determinants of a panel of strains previously analyzed for their plant tissue occupancy using double fluorescent labeling. The reported strategy will be useful for detailed studies on the genomic aspects of the evolution of bacterial symbiosis and for an extensive evaluation of rhizobial inoculants.
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15
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Gourion B, Ratet P. Avoidance of detrimental defense responses in beneficial plant-microbe interactions. Curr Opin Biotechnol 2021; 70:266-272. [PMID: 34252756 DOI: 10.1016/j.copbio.2021.06.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 06/07/2021] [Accepted: 06/15/2021] [Indexed: 12/21/2022]
Abstract
In the environment microbes interact with plants and provide them with benefits that include protection against biotic and abiotic stresses as well as improved nutrition. However, plants are also exposed to parasites and pathogens. To manage appropriate responses, evolution has resulted in improved tolerance of plants to beneficial microbes while keeping the ability to recognize detrimental ones and to develop defense responses. Here we review the mechanisms involved in these interactions. We also discuss how the interactions might be handled to improve crop resistance to pathogens without losing the ability to establish beneficial interactions.
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Affiliation(s)
- Benjamin Gourion
- LIPME, Université de Toulouse, INRAE, CNRS, Castanet-Tolosan, France
| | - Pascal Ratet
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France; Institute of Plant Sciences Paris-Saclay IPS2, Paris Diderot, Sorbonne Paris-Cité, Bâtiment 630, 91405, Orsay, France.
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16
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Ilahi H, Hsouna J, Ellouze W, Gritli T, Chihaoui SA, Barhoumi F, Najib Elfeddy M, Bachkouel S, Ouahmane L, Tambong JT, Mnasri B. Phylogenetic study of rhizobia nodulating pea (Pisum sativum) isolated from different geographic locations in Tunisia. Syst Appl Microbiol 2021; 44:126221. [PMID: 34119907 DOI: 10.1016/j.syapm.2021.126221] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 05/12/2021] [Accepted: 05/24/2021] [Indexed: 11/28/2022]
Abstract
Nodulated Pisum sativum plants showed the presence of native rhizobia in 16 out of 23 soil samples collected especially in northern and central Tunisia. A total of 130 bacterial strains were selected and three different ribotypes were revealed after PCR-RFLP analysis. Sequence analyses of rrs and four housekeeping genes (recA, atpD, dnaK and glnII) assigned 35 isolates to Rhizobium laguerreae, R. ruizarguesonis, Agrobacterium radiobacter, Ensifer meliloti and two putative genospecies. R. laguerreae was the most dominant species nodulating P. sativum with 63%. The isolates 21PS7 and 21PS15 were assigned to R. ruizarguesonis, and this is the first report of this species in Tunisia. Two putative new lineages were identified, since strains 25PS6, 10PS4 and 12PS15 clustered distinctly from known rhizobia species but within the R. leguminosarum complex (Rlc) with the most closely related species being R. indicum with 96.4% sequence identity. Similarly, strains 16PS2, 3PS9 and 3PS18 showed 97.4% and 97.6% similarity with R. sophorae and R. laguerreae, respectively. Based on 16S-23S intergenic spacer (IGS) fingerprinting, there was no clear association between the strains and their geographic locations. According to nodC and nodA phylogenies, strains of Rlc species and, interestingly, strain 8PS18 identified as E. meliloti, harbored the symbiotic genes of symbiovar viciae and clustered in two different clades showing heterogeneity within the symbiovar. All these strains nodulated and fixed nitrogen with pea plants. However, the strains belonging to A. radiobacter and the two remaining strains of E. meliloti were unable to nodulate P. sativum, suggesting that they were non-symbiotic strains. The results of this study further suggest that the Tunisian Rhizobium community is more diverse than previously reported.
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Affiliation(s)
- Houda Ilahi
- Laboratory of Legumes and Sustainable Agroecosystems, Centre of Biotechnology of Borj-Cédria, BP 901, Hammam-lif 2050, Tunisia
| | - Jihed Hsouna
- Laboratory of Legumes and Sustainable Agroecosystems, Centre of Biotechnology of Borj-Cédria, BP 901, Hammam-lif 2050, Tunisia
| | - Walid Ellouze
- Agriculture and Agri-Food Canada, Vineland Station, Ontario L0R 2E0, Canada
| | - Takwa Gritli
- Laboratory of Legumes and Sustainable Agroecosystems, Centre of Biotechnology of Borj-Cédria, BP 901, Hammam-lif 2050, Tunisia
| | - Saif-Allah Chihaoui
- Laboratory of Legumes and Sustainable Agroecosystems, Centre of Biotechnology of Borj-Cédria, BP 901, Hammam-lif 2050, Tunisia
| | - Fathi Barhoumi
- Laboratory of Legumes and Sustainable Agroecosystems, Centre of Biotechnology of Borj-Cédria, BP 901, Hammam-lif 2050, Tunisia
| | - Mohamed Najib Elfeddy
- Phytobacteriology Laboratory, Plant Protection Research Unit, CRRA Marrakesh, National Institute for Agronomical Research, Marrakesh 40000, Morocco
| | - Sarra Bachkouel
- Research Support and Technology Transfer Unity, Centre of Biotechnology of Borj-Cédria, BP 901, Hammam-lif 2050, Tunisia
| | - Lahcen Ouahmane
- Laboratory of Microbial Biotechnologies, Agrosciences and Environment, Faculty of Science Semlalia, Cadi Ayyad University, Marrakesh 40000, Morocco
| | - James T Tambong
- Agriculture and Agri-Food Canada, Ottawa, Ontario K1A 0C6, Canada
| | - Bacem Mnasri
- Laboratory of Legumes and Sustainable Agroecosystems, Centre of Biotechnology of Borj-Cédria, BP 901, Hammam-lif 2050, Tunisia.
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17
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Quides KW, Weisberg AJ, Trinh J, Salaheldine F, Cardenas P, Lee HH, Jariwala R, Chang JH, Sachs JL. Experimental evolution can enhance benefits of rhizobia to novel legume hosts. Proc Biol Sci 2021; 288:20210812. [PMID: 34034525 PMCID: PMC8150021 DOI: 10.1098/rspb.2021.0812] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Legumes preferentially associate with and reward beneficial rhizobia in root nodules, but the processes by which rhizobia evolve to provide benefits to novel hosts remain poorly understood. Using cycles of in planta and in vitro evolution, we experimentally simulated lifestyles where rhizobia repeatedly interact with novel plant genotypes with which they initially provide negligible benefits. Using a full-factorial replicated design, we independently evolved two rhizobia strains in associations with each of two Lotus japonicus genotypes that vary in regulation of nodule formation. We evaluated phenotypic evolution of rhizobia by quantifying fitness, growth effects and histological features on hosts, and molecular evolution via genome resequencing. Rhizobia evolved enhanced host benefits and caused changes in nodule development in one of the four host–symbiont combinations, that appeared to be driven by reduced costs during symbiosis, rather than increased nitrogen fixation. Descendant populations included genetic changes that could alter rhizobial infection or proliferation in host tissues, but lack of evidence for fixation of these mutations weakens the results. Evolution of enhanced rhizobial benefits occurred only in a subset of experiments, suggesting a role for host–symbiont genotype interactions in mediating the evolution of enhanced benefits from symbionts.
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Affiliation(s)
- Kenjiro W Quides
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, USA
| | - Alexandra J Weisberg
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA
| | - Jerry Trinh
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, USA
| | - Fathi Salaheldine
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, USA
| | - Paola Cardenas
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, USA
| | - Hsu-Han Lee
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, USA
| | - Ruchi Jariwala
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, USA
| | - Jeff H Chang
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA
| | - Joel L Sachs
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, USA.,Department of Microbiology and Plant Pathology, University of California, Riverside, CA, USA.,Institute for Integrative Genome Biology, University of California, Riverside, CA, USA
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18
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Alfalfa for a Sustainable Ovine Farming System: Proposed Research for a New Feeding Strategy Based on Alfalfa and Ecological Leftovers in Drought Conditions. SUSTAINABILITY 2021. [DOI: 10.3390/su13073880] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In the past 10 years, the average demand for meat and milk across the world has significantly increased, especially in developing countries. Therefore, to support the production of animal-derived food products, a huge quantity of feed resources is needed. This paper does not present original research, but rather provides a conceptual strategy to improve primary production in a sustainable way, in relation to forthcoming issues linked to climate change. Increases in meat and milk production could be achieved by formulating balanced diets for ovines based on alfalfa integrated with local agricultural by-products. As the central component of the diet is alfalfa, one goal of the project is increasing the yield of alfalfa in a sustainable way via inoculating seeds with symbiotic rhizobia (i.e., Sinorhizobium meliloti). Seed inoculants are already present on the market but have not been optimized for arid soils. Furthermore, a part of the project is focused on the selection of elite symbiotic strains that show increased resistance to salt stress and competitiveness. The second component of the experimental diets is bio-waste, especially that obtained from olive oil manufacturing (i.e., pomace). The addition of agro-by-products allows us to use such waste as a resource for animal feeding, and possibly, to modulate rumen metabolism, thereby increasing the nutritional quality of milk and meat.
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19
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Abstract
Rhizobia are a phylogenetically diverse group of soil bacteria that engage in mutualistic interactions with legume plants. Although specifics of the symbioses differ between strains and plants, all symbioses ultimately result in the formation of specialized root nodule organs which host the nitrogen-fixing microsymbionts called bacteroids. Inside nodules, bacteroids encounter unique conditions that necessitate global reprogramming of physiological processes and rerouting of their metabolism. Decades of research have addressed these questions using genetics, omics approaches, and more recently computational modelling. Here we discuss the common adaptations of rhizobia to the nodule environment that define the core principles of bacteroid functioning. All bacteroids are growth-arrested and perform energy-intensive nitrogen fixation fueled by plant-provided C4-dicarboxylates at nanomolar oxygen levels. At the same time, bacteroids are subject to host control and sanctioning that ultimately determine their fitness and have fundamental importance for the evolution of a stable mutualistic relationship.
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20
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Young JPW, Moeskjær S, Afonin A, Rahi P, Maluk M, James EK, Cavassim MIA, Rashid MHO, Aserse AA, Perry BJ, Wang ET, Velázquez E, Andronov EE, Tampakaki A, Flores Félix JD, Rivas González R, Youseif SH, Lepetit M, Boivin S, Jorrin B, Kenicer GJ, Peix Á, Hynes MF, Ramírez-Bahena MH, Gulati A, Tian CF. Defining the Rhizobium leguminosarum Species Complex. Genes (Basel) 2021; 12:111. [PMID: 33477547 PMCID: PMC7831135 DOI: 10.3390/genes12010111] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/08/2021] [Accepted: 01/13/2021] [Indexed: 01/21/2023] Open
Abstract
Bacteria currently included in Rhizobium leguminosarum are too diverse to be considered a single species, so we can refer to this as a species complex (the Rlc). We have found 429 publicly available genome sequences that fall within the Rlc and these show that the Rlc is a distinct entity, well separated from other species in the genus. Its sister taxon is R. anhuiense. We constructed a phylogeny based on concatenated sequences of 120 universal (core) genes, and calculated pairwise average nucleotide identity (ANI) between all genomes. From these analyses, we concluded that the Rlc includes 18 distinct genospecies, plus 7 unique strains that are not placed in these genospecies. Each genospecies is separated by a distinct gap in ANI values, usually at approximately 96% ANI, implying that it is a 'natural' unit. Five of the genospecies include the type strains of named species: R. laguerreae, R. sophorae, R. ruizarguesonis, "R. indicum" and R. leguminosarum itself. The 16S ribosomal RNA sequence is remarkably diverse within the Rlc, but does not distinguish the genospecies. Partial sequences of housekeeping genes, which have frequently been used to characterize isolate collections, can mostly be assigned unambiguously to a genospecies, but alleles within a genospecies do not always form a clade, so single genes are not a reliable guide to the true phylogeny of the strains. We conclude that access to a large number of genome sequences is a powerful tool for characterizing the diversity of bacteria, and that taxonomic conclusions should be based on all available genome sequences, not just those of type strains.
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Affiliation(s)
| | - Sara Moeskjær
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark;
| | - Alexey Afonin
- Laboratory for Genetics of Plant-Microbe Interactions, ARRIAM, Pushkin, 196608 Saint-Petersburg, Russia;
| | - Praveen Rahi
- National Centre for Microbial Resource, National Centre for Cell Science, Pune 411007, India;
| | - Marta Maluk
- Ecological Sciences, The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK; (M.M.); (E.K.J.)
| | - Euan K. James
- Ecological Sciences, The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK; (M.M.); (E.K.J.)
| | - Maria Izabel A. Cavassim
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA;
| | - M. Harun-or Rashid
- Biotechnology Division, Bangladesh Institute of Nuclear Agriculture (BINA), Mymensingh 2202, Bangladesh;
| | - Aregu Amsalu Aserse
- Ecosystems and Environment Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, FI-00014 Helsinki, Finland;
| | - Benjamin J. Perry
- Department of Microbiology and Immunology, University of Otago, Dunedin 9016, New Zealand;
| | - En Tao Wang
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad De México 11340, Mexico;
| | - Encarna Velázquez
- Departamento de Microbiología y Genética, Universidad de Salamanca, Instituto Hispanoluso de Investigaciones Agrarias (CIALE), Unidad Asociada Grupo de Interacción planta-microorganismo (Universidad de Salamanca-IRNASA-CSIC), 37007 Salamanca, Spain; (E.V.); (R.R.G.)
| | - Evgeny E. Andronov
- Department of Microbial Monitoring, ARRIAM, Pushkin, 196608 Saint-Petersburg, Russia;
| | - Anastasia Tampakaki
- Department of Crop Science, Agricultural University of Athens, Iera Odos 75, Votanikos, 11855 Athens, Greece;
| | - José David Flores Félix
- CICS-UBI—Health Sciences Research Centre, University of Beira Interior, 6201-506 Covilhã, Portugal;
| | - Raúl Rivas González
- Departamento de Microbiología y Genética, Universidad de Salamanca, Instituto Hispanoluso de Investigaciones Agrarias (CIALE), Unidad Asociada Grupo de Interacción planta-microorganismo (Universidad de Salamanca-IRNASA-CSIC), 37007 Salamanca, Spain; (E.V.); (R.R.G.)
| | - Sameh H. Youseif
- Department of Microbial Genetic Resources, National Gene Bank (NGB), Agricultural Research Center (ARC), Giza 12619, Egypt;
| | - Marc Lepetit
- Institut Sophia Agrobiotech, UMR INRAE 1355, Université Côte d’Azur, CNRS, 06903 Sophia Antipolis, France;
| | - Stéphane Boivin
- Laboratoire des Symbioses Tropicales et Méditerranéennes, UMR INRAE-IRD-CIRAD-UM2-SupAgro, Campus International de Baillarguet, TA-A82/J, CEDEX 05, 34398 Montpellier, France;
| | - Beatriz Jorrin
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK;
| | - Gregory J. Kenicer
- Royal Botanic Garden Edinburgh, 20A Inverleith Row, Edinburgh EH3 5LR, UK;
| | - Álvaro Peix
- Instituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA-CSIC), Unidad Asociada Grupo de Interacción Planta-Microorganismo (Universidad de Salamanca-IRNASA-CSIC), 37008 Salamanca, Spain;
| | - Michael F. Hynes
- Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada;
| | - Martha Helena Ramírez-Bahena
- Departamento de Didáctica de las Matemáticas y de las Ciencias Experimentales. Universidad de Salamanca, 37008 Salamanca, Spain;
| | - Arvind Gulati
- Microbial Prospection, CSIR-Institute of Himalayan Bioresource Technology, Palampur (H.P.) 176 061, India;
| | - Chang-Fu Tian
- State Key Laboratory of Agrobiotechnology, Rhizobium Research Center, and College of Biological Sciences, China Agricultural University, Beijing 100193, China;
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21
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Analysis of the Interaction between Pisum sativum L. and Rhizobium laguerreae Strains Nodulating This Legume in Northwest Spain. PLANTS 2020; 9:plants9121755. [PMID: 33322342 PMCID: PMC7763339 DOI: 10.3390/plants9121755] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/08/2020] [Accepted: 12/09/2020] [Indexed: 01/01/2023]
Abstract
Pisum sativum L. (pea) is one of the most cultivated grain legumes in European countries due to the high protein content of its seeds. Nevertheless, the rhizobial microsymbionts of this legume have been scarcely studied in these countries. In this work, we analyzed the rhizobial strains nodulating the pea in a region from Northwestern Spain, where this legume is widely cultivated. The isolated strains were genetically diverse, and the phylogenetic analysis of core and symbiotic genes showed that these strains belong to different clusters related to R. laguerreae sv. viciae. Representative strains of these clusters were able to produce cellulose and cellulases, which are two key molecules in the legume infection process. They formed biofilms and produced acyl-homoserine lactones (AHLs), which are involved in the quorum sensing regulation process. They also exhibited several plant growth promotion mechanisms, including phosphate solubilization, siderophore, and indole acetic acid production and symbiotic atmospheric nitrogen fixation. All strains showed high symbiotic efficiency on pea plants, indicating that strains of R. laguerreae sv. viciae are promising candidates for the biofertilization of this legume worldwide.
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22
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Fields B, Moeskjaer S, Friman VP, Andersen SU, Young JPW. MAUI-seq: Metabarcoding using amplicons with unique molecular identifiers to improve error correction. Mol Ecol Resour 2020; 21:703-720. [PMID: 33171018 DOI: 10.1111/1755-0998.13294] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 10/22/2020] [Accepted: 11/05/2020] [Indexed: 12/18/2022]
Abstract
Sequencing and PCR errors are a major challenge when characterizing genetic diversity using high-throughput amplicon sequencing (HTAS). We have developed a multiplexed HTAS method, MAUI-seq, which uses unique molecular identifiers (UMIs) to improve error correction by exploiting variation among sequences associated with a single UMI. Erroneous sequences are recognized because, across the data set, they are over-represented among the minor sequences associated with UMIs. We show that two main advantages of this approach are efficient elimination of chimeric and other erroneous reads, outperforming dada2 and unoise3, and the ability to confidently recognize genuine alleles that are present at low abundance or resemble chimeras. The method provides sensitive and flexible profiling of diversity and is readily adaptable to most HTAS applications, including microbial 16S rRNA profiling and metabarcoding of environmental DNA.
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Affiliation(s)
| | - Sara Moeskjaer
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | | | - Stig U Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
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23
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Youseif SH, Abd El-Megeed FH, Mohamed AH, Ageez A, Veliz E, Martínez-Romero E. Diverse Rhizobium strains isolated from root nodules of Trifolium alexandrinum in Egypt and symbiovars. Syst Appl Microbiol 2020; 44:126156. [PMID: 33232849 DOI: 10.1016/j.syapm.2020.126156] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 11/01/2020] [Accepted: 11/02/2020] [Indexed: 12/18/2022]
Abstract
Berseem clover (T. alexandrinum) is the main forage legume crop used as animal feed in Egypt. Here, eighty rhizobial isolates were isolated from root nodules of berseem clover grown in different regions in Egypt and were grouped by RFLP-16S rRNA ribotyping. Representative isolates were characterized using phylogenetic analyses of the 16S rRNA, rpoB, glnA, pgi, and nodC genes. We also investigated the performance of these isolates using phenotypic tests and nitrogen fixation efficiency assays. The majority of strains (<90%) were closely related to Rhizobium aegyptiacum and Rhizobium aethiopicum and of the remaining strains, six belonged to the Rhizobium leguminosarum genospecies complex and only one strain was assigned to Agrobacterium fabacearum. Despite their heterogeneous chromosomal background, most of the strains shared nodC gene alleles corresponding to symbiovar trifolii. Some of the strains closely affiliated to R. aegyptiacum and R. aethiopicum had superior nodulation and nitrogen fixation capabilities in berseem clover, compared to the commercial inoculant (Okadein®) and N-added treatments. R. leguminosarum strain NGB-CR 17 that harbored a nodC allele typical of symbiovar viciae, was also able to form an effective symbiosis with clover. Two strains with nodC alleles of symbiovar trifolii, R. aegyptiacum strains NGB-CR 129 and 136, were capable of forming effective nodules in Phaseolus vulgaris in axenic greenhouse conditions. This adds the symbiovar trifolii which is well-established in the Egyptian soils to the list of symbiovars that form nodules in P. vulgaris.
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Affiliation(s)
- Sameh H Youseif
- Department of Microbial Genetic Resources, National Gene Bank, Agricultural Research Center (ARC), Giza 12619, Egypt.
| | - Fayrouz H Abd El-Megeed
- Department of Microbial Genetic Resources, National Gene Bank, Agricultural Research Center (ARC), Giza 12619, Egypt
| | - Akram H Mohamed
- Department of Microbial Genetic Resources, National Gene Bank, Agricultural Research Center (ARC), Giza 12619, Egypt
| | - Amr Ageez
- Agricultural Genetic Engineering Research Institute, Agricultural Research Center (ARC), Giza 12619, Egypt; Faculty of Biotechnology, MSA University, 6 October City, Egypt
| | - Esteban Veliz
- Department of Plant Biology, University of California, Davis, Life Sciences Addition, 1 Shields Ave., Davis, CA, 95616, USA
| | - Esperanza Martínez-Romero
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, UNAM Cuernavaca, Morelos, Mexico
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24
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Liana T. Burghardt. THE NEW PHYTOLOGIST 2020; 228:24-25. [PMID: 33448399 DOI: 10.1111/nph.16869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
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25
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Efstathiadou E, Savvas D, Tampakaki AP. Genetic diversity and phylogeny of indigenous rhizobia nodulating faba bean (Vicia faba L.) in Greece. Syst Appl Microbiol 2020; 43:126149. [PMID: 33161357 DOI: 10.1016/j.syapm.2020.126149] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 08/19/2020] [Accepted: 09/19/2020] [Indexed: 12/16/2022]
Abstract
The genetic diversity and phylogeny of fast-growing rhizobia isolated from root nodules of Vicia faba grown in different geographical regions of Greece were assessed. Although Rhizobium leguminosarum sv. viciae is the most common symbiont of Vicia spp. in European soils, there is no available information on native rhizobia nodulating faba bean in Greece. Seventy bacterial strains were isolated and grouped into sixteen distinct profiles based on BOX-PCR fingerprinting. The phylogenetic affiliation was further defined by sequence analysis of the rrs and multilocus sequence analysis (MLSA) of three housekeeping genes (recA, atpD and gyrB). Fifty-eight isolates were affiliated with recently described genospecies gsF-2, represented by R. laguerreae FB206T, whereas six isolates were closely related to gsB and two isolates might belong to gsA. Two isolates assigned to R. hidalgonense and another two non-nodulating strains could not be assigned to any validly defined species and possibly belong to a new rhizobial lineage. Interestingly, R. laguerreae strains were commonly found at all sampling sites, suggesting that they could be the main symbionts of faba beans in Greek soils. According to the phylogenies of two symbiosis-related genes (nodC and nifH), all nodulating isolates belonged to symbiovar (sv.) viciae harboring four distinct nodC gene haplotypes and they were grouped into two clades together with strains assigned to R. laguerreae and genospecies of R. leguminosarum isolated from other countries and continents. This is the first report that R. hidalgonense strains belong to sv. viciae. No correlation was observed between the nodC haplotypes, geographic origin and chromosomal background of the isolates in the study.
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Affiliation(s)
- Evdoxia Efstathiadou
- Laboratory of General and Agricultural Microbiology, Department of Crop Science, Agricultural University of Athens, Iera Odos 75, Votanikos, 11855 Athens, Greece
| | - Dimitrios Savvas
- Laboratory of Vegetable Production, Department of Crop Science, Agricultural University of Athens, Iera Odos 75, Votanikos, 11855 Athens, Greece
| | - Anastasia P Tampakaki
- Laboratory of General and Agricultural Microbiology, Department of Crop Science, Agricultural University of Athens, Iera Odos 75, Votanikos, 11855 Athens, Greece.
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