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Adaptive Evolution of Rhizobial Symbiosis beyond Horizontal Gene Transfer: From Genome Innovation to Regulation Reconstruction. Genes (Basel) 2023; 14:genes14020274. [PMID: 36833201 PMCID: PMC9957244 DOI: 10.3390/genes14020274] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 01/22/2023] Open
Abstract
There are ubiquitous variations in symbiotic performance of different rhizobial strains associated with the same legume host in agricultural practices. This is due to polymorphisms of symbiosis genes and/or largely unexplored variations in integration efficiency of symbiotic function. Here, we reviewed cumulative evidence on integration mechanisms of symbiosis genes. Experimental evolution, in concert with reverse genetic studies based on pangenomics, suggests that gain of the same circuit of key symbiosis genes through horizontal gene transfer is necessary but sometimes insufficient for bacteria to establish an effective symbiosis with legumes. An intact genomic background of the recipient may not support the proper expression or functioning of newly acquired key symbiosis genes. Further adaptive evolution, through genome innovation and reconstruction of regulation networks, may confer the recipient of nascent nodulation and nitrogen fixation ability. Other accessory genes, either co-transferred with key symbiosis genes or stochastically transferred, may provide the recipient with additional adaptability in ever-fluctuating host and soil niches. Successful integrations of these accessory genes with the rewired core network, regarding both symbiotic and edaphic fitness, can optimize symbiotic efficiency in various natural and agricultural ecosystems. This progress also sheds light on the development of elite rhizobial inoculants using synthetic biology procedures.
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Liebrenz K, Gómez C, Brambilla S, Frare R, Stritzler M, Maguire V, Ruiz O, Soldini D, Pascuan C, Soto G, Ayub N. Whole-Genome Resequencing of Spontaneous Oxidative Stress-Resistant Mutants Reveals an Antioxidant System of Bradyrhizobium japonicum Involved in Soybean Colonization. MICROBIAL ECOLOGY 2022; 84:1133-1140. [PMID: 34782938 DOI: 10.1007/s00248-021-01925-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 11/09/2021] [Indexed: 06/13/2023]
Abstract
Soybean is the most inoculant-consuming crop in the world, carrying strains belonging to the extremely related species Bradyrhizobium japonicum and Bradyrhizobium diazoefficiens. Currently, it is well known that B. japonicum has higher efficiency of soybean colonization than B. diazoefficiens, but the molecular mechanism underlying this differential symbiotic performance remains unclear. In the present study, genome resequencing of four spontaneous oxidative stress-resistant mutants derived from the commercial strain B. japonicum E109 combined with molecular and physiological studies allowed identifying an antioxidant cluster (BjAC) containing a transcriptional regulator (glxA) that controls the expression of a catalase (catA) and a phosphohydrolase (yfbR) related to the hydrolysis of hydrogen peroxide and oxidized nucleotides, respectively. Integrated synteny and phylogenetic analyses supported the fact that BjAC emergence in the B. japonicum lineage occurred after its divergence from the B. diazoefficiens lineage. The transformation of the model bacterium B. diazoefficiens USDA110 with BjAC from E109 significantly increased its ability to colonize soybean roots, experimentally recapitulating the beneficial effects of the occurrence of BjAC in B. japonicum. In addition, the glxA mutation significantly increased the nodulation competitiveness and plant growth-promoting efficiency of E109. Finally, the potential applications of these types of non-genetically modified mutant microbes in soybean production worldwide are discussed.
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Affiliation(s)
- Karen Liebrenz
- Instituto de Agrobiotecnología Y Biología Molecular (INTA-CONICET), Buenos Aires, Argentina
- Instituto de Genética (IGEAF), INTA, De los Reseros S/N, Castelar C25(1712), Buenos Aires, Argentina
| | - Cristina Gómez
- Instituto de Agrobiotecnología Y Biología Molecular (INTA-CONICET), Buenos Aires, Argentina
- Instituto de Genética (IGEAF), INTA, De los Reseros S/N, Castelar C25(1712), Buenos Aires, Argentina
| | - Silvina Brambilla
- Instituto de Agrobiotecnología Y Biología Molecular (INTA-CONICET), Buenos Aires, Argentina
- Instituto de Genética (IGEAF), INTA, De los Reseros S/N, Castelar C25(1712), Buenos Aires, Argentina
| | - Romina Frare
- Instituto de Agrobiotecnología Y Biología Molecular (INTA-CONICET), Buenos Aires, Argentina
- Instituto de Genética (IGEAF), INTA, De los Reseros S/N, Castelar C25(1712), Buenos Aires, Argentina
| | - Margarita Stritzler
- Instituto de Agrobiotecnología Y Biología Molecular (INTA-CONICET), Buenos Aires, Argentina
- Instituto de Genética (IGEAF), INTA, De los Reseros S/N, Castelar C25(1712), Buenos Aires, Argentina
| | - Vanina Maguire
- Instituto Tecnológico Chascomús (INTECH-CONICET), Buenos Aires, Argentina
| | - Oscar Ruiz
- Instituto Tecnológico Chascomús (INTECH-CONICET), Buenos Aires, Argentina
| | - Diego Soldini
- Estación Experimental Agropecuaria Marcos Juárez, INTA, Córdoba, Argentina
| | - Cecilia Pascuan
- Instituto de Agrobiotecnología Y Biología Molecular (INTA-CONICET), Buenos Aires, Argentina
- Instituto de Genética (IGEAF), INTA, De los Reseros S/N, Castelar C25(1712), Buenos Aires, Argentina
| | - Gabriela Soto
- Instituto de Agrobiotecnología Y Biología Molecular (INTA-CONICET), Buenos Aires, Argentina
- Instituto de Genética (IGEAF), INTA, De los Reseros S/N, Castelar C25(1712), Buenos Aires, Argentina
| | - Nicolás Ayub
- Instituto de Agrobiotecnología Y Biología Molecular (INTA-CONICET), Buenos Aires, Argentina.
- Instituto de Genética (IGEAF), INTA, De los Reseros S/N, Castelar C25(1712), Buenos Aires, Argentina.
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Liebrenz K, Frare R, Gómez C, Pascuan C, Brambilla S, Soldini D, Maguire V, Carrio A, Ruiz O, McCormick W, Soto G, Ayub N. Multiple ways to evade the bacteriostatic action of glyphosate in rhizobia include the mutation of the conserved serine 90 of the nitrogenase subunit NifH to alanine. Res Microbiol 2022; 173:103952. [PMID: 35436545 DOI: 10.1016/j.resmic.2022.103952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 04/03/2022] [Accepted: 04/08/2022] [Indexed: 11/30/2022]
Abstract
The genome resequencing of spontaneous glyphosate-resistant mutants derived from the soybean inoculant E109 allowed identifying genes most likely associated with the uptake (gltL and cya) and metabolism (zigA and betA) of glyphosate, as well as with nitrogen fixation (nifH). Mutations in these genes reduce the lag phase and improve nodulation under glyphosate stress. In addition to providing glyphosate resistance, the amino acid exchange Ser90Ala in NifH increased the citrate synthase activity, growth rate and plant growth-promoting efficiency of E109 in the absence of glyphosate stress, suggesting roles for this site during both the free-living and symbiotic growth stages.
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Affiliation(s)
- Karen Liebrenz
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), Buenos Aires, Argentina; Instituto de Genética (IGEAF), Buenos Aires, Argentina
| | - Romina Frare
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), Buenos Aires, Argentina; Instituto de Genética (IGEAF), Buenos Aires, Argentina
| | - Cristina Gómez
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), Buenos Aires, Argentina; Instituto de Genética (IGEAF), Buenos Aires, Argentina
| | - Cecilia Pascuan
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), Buenos Aires, Argentina; Instituto de Genética (IGEAF), Buenos Aires, Argentina
| | - Silvina Brambilla
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), Buenos Aires, Argentina; Instituto de Genética (IGEAF), Buenos Aires, Argentina
| | - Diego Soldini
- Estación Experimental Agropecuaria Marcos Juárez, INTA, Córdoba, Argentina
| | - Vanina Maguire
- Instituto Tecnológico Chascomús (INTECH-CONICET), Buenos Aires, Argentina
| | - Alejandro Carrio
- Estación Experimental Agropecuaria Marcos Juárez, INTA, Córdoba, Argentina
| | - Oscar Ruiz
- Instituto Tecnológico Chascomús (INTECH-CONICET), Buenos Aires, Argentina
| | - Wayne McCormick
- Ottawa Research and Development Centre (AAFC), Ottawa, ON, Canada
| | - Gabriela Soto
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), Buenos Aires, Argentina; Instituto de Genética (IGEAF), Buenos Aires, Argentina
| | - Nicolás Ayub
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), Buenos Aires, Argentina; Instituto de Genética (IGEAF), Buenos Aires, Argentina.
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Frare R, Pascuan C, Galindo-Sotomonte L, McCormick W, Soto G, Ayub N. Exploring the Role of the NO-Detoxifying Enzyme HmpA in the Evolution of Domesticated Alfalfa Rhizobia. MICROBIAL ECOLOGY 2022; 83:501-505. [PMID: 33966095 DOI: 10.1007/s00248-021-01761-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 04/19/2021] [Indexed: 06/12/2023]
Abstract
We have previously shown the extensive loss of genes during the domestication of alfalfa rhizobia and the high nitrous oxide emission associated with the extreme genomic instability of commercial inoculants. In the present note, we describe the molecular mechanism involved in the evolution of alfalfa rhizobia. Genomic analysis showed that most of the gene losses in inoculants are due to large genomic deletions rather than to small deletions or point mutations, a fact consistent with recurrent DNA double-strand breaks (DSBs) at numerous locations throughout the microbial genome. Genetic analysis showed that the loss of the NO-detoxifying enzyme HmpA in inoculants results in growth inhibition and high DSB levels under nitrosative stress, and large genomic deletions in planta but not in the soil. Therefore, besides its known function in the effective establishment of the symbiosis, HmpA can play a critical role in the preservation of the genomic integrity of alfalfa rhizobia under host-derived nitrosative stress.
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Affiliation(s)
- Romina Frare
- Instituto de Agrobiotecnología y Biología Molecular (INTA-CONICET), Buenos Aires, Argentina
- Instituto de Genética (INTA), De Los Reseros S/N, Castelar C25(1712), Buenos Aires, Argentina
| | - Cecilia Pascuan
- Instituto de Agrobiotecnología y Biología Molecular (INTA-CONICET), Buenos Aires, Argentina
- Instituto de Genética (INTA), De Los Reseros S/N, Castelar C25(1712), Buenos Aires, Argentina
| | - Luisa Galindo-Sotomonte
- Instituto de Agrobiotecnología y Biología Molecular (INTA-CONICET), Buenos Aires, Argentina
- Instituto de Genética (INTA), De Los Reseros S/N, Castelar C25(1712), Buenos Aires, Argentina
| | - Wayne McCormick
- Ottawa Research and Development Centre (AAFC), Ottawa, ON, Canada
| | - Gabriela Soto
- Instituto de Agrobiotecnología y Biología Molecular (INTA-CONICET), Buenos Aires, Argentina
- Instituto de Genética (INTA), De Los Reseros S/N, Castelar C25(1712), Buenos Aires, Argentina
| | - Nicolás Ayub
- Instituto de Agrobiotecnología y Biología Molecular (INTA-CONICET), Buenos Aires, Argentina.
- Instituto de Genética (INTA), De Los Reseros S/N, Castelar C25(1712), Buenos Aires, Argentina.
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Primo ED, Cossovich S, Nievas F, Bogino P, Humm EA, Hirsch AM, Giordano W. Exopolysaccharide production in Ensifer meliloti laboratory and native strains and their effects on alfalfa inoculation. Arch Microbiol 2019; 202:391-398. [PMID: 31680188 DOI: 10.1007/s00203-019-01756-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 10/07/2019] [Accepted: 10/22/2019] [Indexed: 01/22/2023]
Abstract
Bacterial surface molecules have an important role in the rhizobia-legume symbiosis. Ensifer meliloti (previously, Sinorhizobium meliloti), a symbiotic Gram-negative rhizobacterium, produces two different exopolysaccharides (EPSs), termed EPS I (succinoglycan) and EPS II (galactoglucan), with different functions in the symbiotic process. Accordingly, we undertook a study comparing the potential differences in alfalfa nodulation by E. meliloti strains with differences in their EPSs production. Strains recommended for inoculation as well as laboratory strains and native strains isolated from alfalfa fields were investigated. This study concentrated on EPS-II production, which results in mucoid colonies that are dependent on the presence of an intact expR gene. The results revealed that although the studied strains exhibited different phenotypes, the differences did not affect alfalfa nodulation itself. However, subtle changes in timing and efficacy to the effects of inoculation with the different strains may result because of other as-yet unknown factors. Thus, additional research is needed to determine the most effective inoculant strains and the best conditions for improving alfalfa production under agricultural conditions.
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Affiliation(s)
- Emiliano D Primo
- Departamento de Biología Molecular, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina
| | - Sacha Cossovich
- Departamento de Biología Molecular, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina
| | - Fiorela Nievas
- Departamento de Biología Molecular, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina
| | - Pablo Bogino
- Departamento de Biología Molecular, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina
| | - Ethan A Humm
- Department of Molecular, Cell and Developmental Biology, University of California-Los Angeles, Los Angeles, USA
| | - Ann M Hirsch
- Department of Molecular, Cell and Developmental Biology, University of California-Los Angeles, Los Angeles, USA.,Molecular Biology Institute, University of California-Los Angeles, Los Angeles, USA
| | - Walter Giordano
- Departamento de Biología Molecular, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina.
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Brambilla S, Frare R, Soto G, Jozefkowicz C, Ayub N. Absence of the Nitrous Oxide Reductase Gene Cluster in Commercial Alfalfa Inoculants Is Probably Due to the Extensive Loss of Genes During Rhizobial Domestication. MICROBIAL ECOLOGY 2018; 76:299-302. [PMID: 29330647 DOI: 10.1007/s00248-018-1145-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 01/02/2018] [Indexed: 06/07/2023]
Abstract
As other legume crops, alfalfa cultivation increases the emission of the greenhouse gas nitrous oxide (N2O). Since legume-symbiotic nitrogen-fixing bacteria play a crucial role in this emission, it is important to understand the possible impacts of rhizobial domestication on the evolution of denitrification genes. In comparison with the genomes of non-commercial strains, those of commercial alfalfa inoculants exhibit low total genome size, low number of ORFs and high numbers of both frameshifted genes and pseudogenes, suggesting a dramatic loss of genes during bacterial domestication. Genomic analysis focused on denitrification genes revealed that commercial strains have perfectly conserved the nitrate (NAP), nitrite (NIR) and nitric (NOR) reductase clusters related to the production of N2O from nitrate but completely lost the nitrous oxide (NOS) reductase cluster (nosRZDFYLX genes) associated with the reduction of N2O to gas nitrogen. Based on these results, we propose future screenings for alfalfa-nodulating isolates containing both nitrogen fixation and N2O reductase genes for environmental sustainability of alfalfa production.
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Affiliation(s)
- Silvina Brambilla
- Instituto de Genética Ewald A. Favret (INTA), De los Reseros S/N, C25(1712), Castelar, Buenos Aires, Argentina
| | - Romina Frare
- Instituto de Genética Ewald A. Favret (INTA), De los Reseros S/N, C25(1712), Castelar, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, CABA, Argentina
| | - Gabriela Soto
- Instituto de Genética Ewald A. Favret (INTA), De los Reseros S/N, C25(1712), Castelar, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, CABA, Argentina
| | - Cintia Jozefkowicz
- Instituto de Genética Ewald A. Favret (INTA), De los Reseros S/N, C25(1712), Castelar, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, CABA, Argentina
| | - Nicolás Ayub
- Instituto de Genética Ewald A. Favret (INTA), De los Reseros S/N, C25(1712), Castelar, Buenos Aires, Argentina.
- Consejo Nacional de Investigaciones Científicas y Técnicas, CABA, Argentina.
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Stritzler M, Elba P, Berini C, Gomez C, Ayub N, Soto G. High-quality forage production under salinity by using a salt-tolerant AtNXH1-expressing transgenic alfalfa combined with a natural stress-resistant nitrogen-fixing bacterium. J Biotechnol 2018; 276-277:42-45. [DOI: 10.1016/j.jbiotec.2018.04.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Revised: 03/26/2018] [Accepted: 04/18/2018] [Indexed: 11/16/2022]
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