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Soto-Valenzuela JO, Ormeño-Orrillo E, Zúñiga-Dávila D. Diversidad de rizobios y fijación biológica de nitrógeno en aislados de Clitoria brachystegia, en remanentes de bosque seco tropical de Ecuador y Perú. REV MEX BIODIVERS 2021. [DOI: 10.22201/ib.20078706e.2021.92.3426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Ramírez MDA, España M, Aguirre C, Kojima K, Ohkama-Ohtsu N, Sekimoto H, Yokoyama T. Burkholderia and Paraburkholderia are Predominant Soybean Rhizobial Genera in Venezuelan Soils in Different Climatic and Topographical Regions. Microbes Environ 2019; 34:43-58. [PMID: 30773514 PMCID: PMC6440732 DOI: 10.1264/jsme2.me18076] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Accepted: 10/25/2018] [Indexed: 11/12/2022] Open
Abstract
The climate, topography, fauna, and flora of Venezuela are highly diverse. However, limited information is currently available on the characterization of soybean rhizobia in Venezuela. To clarify the physiological and genetic diversities of soybean rhizobia in Venezuela, soybean root nodules were collected from 11 soil types located in different topographical regions. A total of 395 root nodules were collected and 120 isolates were obtained. All isolates were classified in terms of stress tolerance under different concentrations of NaCl and Al3+. The tolerance levels of isolates to NaCl and Al3+ varied. Based on sampling origins and stress tolerance levels, 44 isolates were selected for further characterization. An inoculation test indicated that all isolates showed the capacity for root nodulation on soybean. Based on multilocus sequence typing (MLST), 20 isolates were classified into the genera Rhizobium and Bradyrhizobium. The remaining 24 isolates were classified into the genus Burkholderia or Paraburkholderia. There is currently no evidence to demonstrate that the genera Burkholderia and Paraburkholderia are the predominant soybean rhizobia in agricultural fields. Of the 24 isolates classified in (Para) Burkholderia, the nodD-nodB intergenic spacer regions of 10 isolates and the nifH gene sequences of 17 isolates were closely related to the genera Rhizobium and Bradyrhizobium, respectively. The root nodulation numbers of five (Para) Burkholderia isolates were higher than those of the 20 α-rhizobia. Furthermore, among the 44 isolates tested, one Paraburkholderia isolate exhibited the highest nitrogen-fixation activity in root nodules.
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Affiliation(s)
- María Daniela Artigas Ramírez
- United Graduate School of Agriculture, Tokyo University of Agriculture and Technology (TUAT)Saiwai-cho 3–5–8, Fuchu, Tokyo 183–8509Japan
| | | | | | - Katsuhiro Kojima
- Faculty of Agriculture, Tokyo University of Agriculture and Technology183–8509Japan
| | - Naoko Ohkama-Ohtsu
- Institute of Agriculture, Tokyo University of Agriculture and Technology (TUAT)Saiwai-cho 3–5–8, Fuchu, Tokyo 183–8509Japan
| | - Hitoshi Sekimoto
- Faculty of Agriculture, Utsunomiya UniversityUtsunomiya 321–8505Japan
| | - Tadashi Yokoyama
- Institute of Agriculture, Tokyo University of Agriculture and Technology (TUAT)Saiwai-cho 3–5–8, Fuchu, Tokyo 183–8509Japan
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Beukes CW, Stępkowski T, Venter SN, Cłapa T, Phalane FL, le Roux MM, Steenkamp ET. Crotalarieae and Genisteae of the South African Great Escarpment are nodulated by novel Bradyrhizobium species with unique and diverse symbiotic loci. Mol Phylogenet Evol 2016; 100:206-218. [DOI: 10.1016/j.ympev.2016.04.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 03/30/2016] [Accepted: 04/07/2016] [Indexed: 12/21/2022]
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Tian R, Parker M, Seshadri R, Reddy T, Markowitz V, Ivanova N, Pati A, Woyke T, Baeshen M, Baeshen N, Kyrpides N, Reeve W. High-quality permanent draft genome sequence of Bradyrhizobium sp. Ai1a-2; a microsymbiont of Andira inermis discovered in Costa Rica. Stand Genomic Sci 2015; 10:33. [PMID: 26380037 PMCID: PMC4571121 DOI: 10.1186/s40793-015-0007-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 04/16/2015] [Indexed: 11/30/2022] Open
Abstract
Bradyrhizobium sp. Ai1a-2 is is an aerobic, motile, Gram-negative, non-spore-forming rod that was isolated from an effective nitrogen fixing root nodule of Andira inermis collected from Tres Piedras in Costa Rica. In this report we describe, for the first time, the genome sequence information and annotation of this legume microsymbiont. The 9,029,266 bp genome has a GC content of 62.56% with 247 contigs arranged into 246 scaffolds. The assembled genome contains 8,482 protein-coding genes and 102 RNA-only encoding genes. This rhizobial genome was sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project proposal.
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Affiliation(s)
- Rui Tian
- Centre for Rhizobium Studies, Murdoch University, Murdoch, Australia
| | - Matthew Parker
- Binghamton University, State University of New York, New York, USA
| | - Rekha Seshadri
- DOE Joint Genome Institute, Walnut Creek, California USA
| | - Tbk Reddy
- DOE Joint Genome Institute, Walnut Creek, California USA
| | - Victor Markowitz
- Biological Data Management and Technology Center, Lawrence Berkeley National Laboratory, Berkeley, California USA
| | | | - Amrita Pati
- DOE Joint Genome Institute, Walnut Creek, California USA
| | - Tanja Woyke
- DOE Joint Genome Institute, Walnut Creek, California USA
| | - Mohammed Baeshen
- Center of Nanotechnology, King Abdulaziz University, Jeddah, Saudi Arabia ; Department of Biological Sciences, Faculty of Science, Jeddah University, Jeddah, Saudi Arabia
| | - Nabih Baeshen
- Center of Nanotechnology, King Abdulaziz University, Jeddah, Saudi Arabia ; Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Nikos Kyrpides
- DOE Joint Genome Institute, Walnut Creek, California USA ; Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Wayne Reeve
- Centre for Rhizobium Studies, Murdoch University, Murdoch, Australia
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Zilli JE, Baraúna AC, da Silva K, De Meyer SE, Farias ENC, Kaminski PE, da Costa IB, Ardley JK, Willems A, Camacho NN, Dourado FDS, O'Hara G. Bradyrhizobium neotropicale sp. nov., isolated from effective nodules of Centrolobium paraense. Int J Syst Evol Microbiol 2014; 64:3950-3957. [PMID: 25205796 DOI: 10.1099/ijs.0.065458-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Root nodule bacteria were isolated from Centrolobium paraense Tul. grown in soils from the Amazon region, State of Roraima (Brazil). 16S rRNA gene sequence analysis of seven strains (BR 10247(T), BR 10296, BR 10297, BR 10298, BR 10299, BR 10300 and BR 10301) placed them in the genus Bradyrhizobium with the closest neighbours being the type strains of Bradyrhizobium paxllaeri (98.8 % similarity), Bradyrhizobium icense (98.8 %), Bradyrhizobium lablabi (98.7 %), Bradyrhizobium jicamae (98.6 %), Bradyrhizobium elkanii (98.6 %), Bradyrhizobium pachyrhizi (98.6 %) and Bradyrhizobium retamae (98.3 %). This high similarity, however, was not confirmed by the intergenic transcribed spacer (ITS) 16S-23S rRNA region sequence analysis nor by multi-locus sequence analysis. Phylogenetic analyses of five housekeeping genes (dnaK, glnII, gyrB, recA and rpoB) revealed Bradyrhizobium iriomotense EK05(T) ( = LMG 24129(T)) to be the most closely related type strain (95.7 % sequence similarity or less). Chemotaxonomic data, including fatty acid profiles [major components being C16 : 0 and summed feature 8 (18 : 1ω6c/18 : 1ω7c)], DNA G+C content, slow growth rate and carbon compound utilization patterns, supported the placement of the novel strains in the genus Bradyrhizobium. Results of DNA-DNA relatedness studies and physiological data (especially carbon source utilization) differentiated the strains from the closest recognized species of the genus Bradyrhizobium. Symbiosis-related genes for nodulation (nodC) and nitrogen fixation (nifH) placed the novel species in a new branch within the genus Bradyrhizobium. Based on the current data, these seven strains represent a novel species for which the name Bradyrhizobium neotropicale sp. nov. is proposed. The type strain is BR 10247(T) ( = HAMBI 3599(T)).
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Affiliation(s)
- Jerri E Zilli
- Embrapa Agrobiologia, Rodovia BR 465 km 07, Seropédica, Rio de Janeiro 23891-000, Brazil
| | - Alexandre C Baraúna
- Universidade Federal Rural do Rio de Janeiro, Rodovia BR 465 km 07, Seropédica, Rio de Janeiro 23890-000, Brazil
| | - Krisle da Silva
- Embrapa Roraima, Rodovia BR 174 km 08, Boa Vista, Roraima 69301-970, Brazil
| | - Sofie E De Meyer
- Laboratory of Microbiology, Department of Biochemistry and Microbiology (WE10), Ghent University, K. L. Ledeganckstraat 35, B-9000 Ghent, Belgium
- Centre for Rhizobium Studies, Murdoch University, 90 South Street, Murdoch 6150, Western Australia, Australia
| | - Eliane N C Farias
- Embrapa Roraima, Rodovia BR 174 km 08, Boa Vista, Roraima 69301-970, Brazil
| | - Paulo E Kaminski
- Embrapa Roraima, Rodovia BR 174 km 08, Boa Vista, Roraima 69301-970, Brazil
| | - Ismaele B da Costa
- Embrapa Roraima, Rodovia BR 174 km 08, Boa Vista, Roraima 69301-970, Brazil
| | - Julie K Ardley
- Centre for Rhizobium Studies, Murdoch University, 90 South Street, Murdoch 6150, Western Australia, Australia
| | - Anne Willems
- Laboratory of Microbiology, Department of Biochemistry and Microbiology (WE10), Ghent University, K. L. Ledeganckstraat 35, B-9000 Ghent, Belgium
| | - Natália N Camacho
- Embrapa Agrobiologia, Rodovia BR 465 km 07, Seropédica, Rio de Janeiro 23891-000, Brazil
| | - Fernanda Dos S Dourado
- Embrapa Agrobiologia, Rodovia BR 465 km 07, Seropédica, Rio de Janeiro 23891-000, Brazil
| | - Graham O'Hara
- Centre for Rhizobium Studies, Murdoch University, 90 South Street, Murdoch 6150, Western Australia, Australia
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Parker MA, Rousteau A. Mosaic origins of Bradyrhizobium legume symbionts on the Caribbean island of Guadeloupe. Mol Phylogenet Evol 2014; 77:110-5. [DOI: 10.1016/j.ympev.2014.04.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 04/04/2014] [Accepted: 04/08/2014] [Indexed: 11/28/2022]
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Ardley JK, Reeve WG, O'Hara GW, Yates RJ, Dilworth MJ, Howieson JG. Nodule morphology, symbiotic specificity and association with unusual rhizobia are distinguishing features of the genus Listia within the Southern African crotalarioid clade Lotononis s.l. ANNALS OF BOTANY 2013; 112:1-15. [PMID: 23712451 PMCID: PMC3690986 DOI: 10.1093/aob/mct095] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 03/25/2013] [Indexed: 05/02/2023]
Abstract
BACKGROUND AND AIMS The legume clade Lotononis sensu lato (s.l.; tribe Crotalarieae) comprises three genera: Listia, Leobordea and Lotononis sensu stricto (s.s.). Listia species are symbiotically specific and form lupinoid nodules with rhizobial species of Methylobacterium and Microvirga. This work investigated whether these symbiotic traits were confined to Listia by determining the ability of rhizobial strains isolated from species of Lotononis s.l. to nodulate Listia, Leobordea and Lotononis s.s. hosts and by examining the morphology and structure of the resulting nodules. METHODS Rhizobia were characterized by sequencing their 16S rRNA and nodA genes. Nodulation and N2 fixation on eight taxonomically diverse Lotononis s.l. species were determined in glasshouse trials. Nodules of all hosts, and the process of infection and nodule initiation in Listia angolensis and Listia bainesii, were examined by light microscopy. KEY RESULTS Rhizobia associated with Lotononis s.l. were phylogenetically diverse. Leobordea and Lotononis s.s. isolates were most closely related to Bradyrhizobium spp., Ensifer meliloti, Mesorhizobium tianshanense and Methylobacterium nodulans. Listia angolensis formed effective nodules only with species of Microvirga. Listia bainesii nodulated only with pigmented Methylobacterium. Five lineages of nodA were found. Listia angolensis and L. bainesii formed lupinoid nodules, whereas nodules of Leobordea and Lotononis s.s. species were indeterminate. All effective nodules contained uniformly infected central tissue. Listia angolensis and L. bainesii nodule initials occurred on the border of the hypocotyl and along the tap root, and nodule primordia developed in the outer cortical layer. Neither root hair curling nor infection threads were seen. CONCLUSIONS Two specificity groups occur within Lotononis s.l.: Listia species are symbiotically specific, while species of Leobordea and Lotononis s.s. are generally promiscuous and interact with rhizobia of diverse chromosomal and symbiotic lineages. The seasonally waterlogged habitat of Listia species may favour the development of symbiotic specificity.
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Affiliation(s)
- Julie K Ardley
- Centre for Rhizobium Studies, Murdoch University, Murdoch WA 6150, Australia.
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Koppell JH, Parker MA. Phylogenetic clustering of Bradyrhizobium symbionts on legumes indigenous to North America. Microbiology (Reading) 2012; 158:2050-2059. [DOI: 10.1099/mic.0.059238-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Jonathan H. Koppell
- Department of Biological Sciences, State University of New York, Binghamton, NY 13902, USA
| | - Matthew A. Parker
- Department of Biological Sciences, State University of New York, Binghamton, NY 13902, USA
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Ormeño-Orrillo E, Rogel-Hernández MA, Lloret L, López-López A, Martínez J, Barois I, Martínez-Romero E. Change in land use alters the diversity and composition of Bradyrhizobium communities and led to the introduction of Rhizobium etli into the tropical rain forest of Los Tuxtlas (Mexico). MICROBIAL ECOLOGY 2012; 63:822-834. [PMID: 22109095 DOI: 10.1007/s00248-011-9974-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 10/24/2011] [Indexed: 05/31/2023]
Abstract
Nitrogen-fixing bacteria of the Bradyrhizobium genus are major symbionts of legume plants in American tropical forests, but little is known about the effects of deforestation and change in land use on their diversity and community structure. Forest clearing is followed by cropping of bean (Phaseolus vulgaris) and maize as intercropped plants in Los Tuxtlas tropical forest of Mexico. The identity of bean-nodulating rhizobia in this area is not known. Using promiscuous trap plants, bradyrhizobia were isolated from soil samples collected in Los Tuxtlas undisturbed forest, and in areas where forest was cleared and land was used as crop fields or as pastures, or where secondary forests were established. Rhizobia were also trapped by using bean plants. Bradyrhizobium strains were classified into genospecies by dnaK sequence analysis supported by recA, glnII and 16S-23S rDNA IGS loci analyses. A total of 29 genospecies were identified, 24 of which did not correspond to any described taxa. A reduction in Bradyrhizobium diversity was observed when forest was turned to crop fields or pastures. Diversity seemed to recover to primary forest levels in secondary forests that derived from abandoned crop fields or pastures. The shifts in diversity were not related to soil characteristics but seemingly to the density of nodulating legumes present at each land use system (LUS). Bradyrhizobium community composition in soils was dependent on land use; however, similarities were observed between crop fields and pastures but not among forest and secondary forest. Most Bradyrhizobium genospecies present in forest were not recovered or become rare in the other LUS. Rhizobium etli was found as the dominant bean-nodulating rhizobia present in crop fields and pastures, and evidence was found that this species was introduced in Los Tuxtlas forest.
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Stępkowski T, Watkin E, McInnes A, Gurda D, Gracz J, Steenkamp ET. Distinct Bradyrhizobium [corrected] communities nodulate legumes native to temperate and tropical monsoon Australia. Mol Phylogenet Evol 2012; 63:265-77. [PMID: 22230030 DOI: 10.1016/j.ympev.2011.12.020] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2011] [Revised: 12/14/2011] [Accepted: 12/19/2011] [Indexed: 11/29/2022]
Abstract
Geographic isolation and growing climate aridity played major roles in the evolution of Australian legumes. It is likely that these two factors also impacted on the evolution of their root-nodule bacteria. To investigate this issue, we applied a multilocus sequence analysis (MLSA) approach to examine Bradyrhizobium isolates originating from temperate areas of Western Australia (WA) and the tropical-monsoon area of the Northern Territory (NT). The isolates were mostly collected from the nodules of legumes belonging to tribes, genera and species endemic or native to Australia. Phylogenetic analyses of sequences for the housekeeping atpD, dnaK, glnII, gyrB, recA and 16S rRNA genes and nodulation nodA gene revealed that most isolates belonged to groups that are distinct from non-Australian Bradyrhizobium isolates, which is in line with earlier studies based on 16S rRNA gene sequence analyses. Phylogenetic analysis of the nodA data allowed identification of five major Clades among the WA and NT isolates. All WA isolates grouped in a subgroup I.1 of Clade I with strains originating from temperate eastern Australia. In contrast, the NT isolates formed part of Clades I (subgroup I.2), III (subgroup III.3), IV, V and X. Of these nodA clades, Clade I, Clade IV, Clade X presumably have an Australian origin. Overall, these data demonstrate that the impact of geographic isolation of the Australian landmass is manifested by the presence of numerous unique clusters in housekeeping and nodulation gene trees. In addition, the intrinsic climate characteristics of temperate WA and tropical-monsoon NT were responsible for the formation of distinct legume communities selecting for unrelated Bradyrhizobium groups.
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Affiliation(s)
- Tomasz Stępkowski
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61 704 Poznań, Poland.
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Mishra RPN, Tisseyre P, Melkonian R, Chaintreuil C, Miché L, Klonowska A, Gonzalez S, Bena G, Laguerre G, Moulin L. Genetic diversity of Mimosa pudica rhizobial symbionts in soils of French Guiana: investigating the origin and diversity of Burkholderia phymatum and other beta-rhizobia. FEMS Microbiol Ecol 2011; 79:487-503. [PMID: 22093060 DOI: 10.1111/j.1574-6941.2011.01235.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 10/14/2011] [Accepted: 10/19/2011] [Indexed: 12/01/2022] Open
Abstract
The genetic diversity of 221 Mimosa pudica bacterial symbionts trapped from eight soils from diverse environments in French Guiana was assessed by 16S rRNA PCR-RFLP, REP-PCR fingerprints, as well as by phylogenies of their 16S rRNA and recA housekeeping genes, and by their nifH, nodA and nodC symbiotic genes. Interestingly, we found a large diversity of beta-rhizobia, with Burkholderia phymatum and Burkholderia tuberum being the most frequent and diverse symbiotic species. Other species were also found, such as Burkholderia mimosarum, an unnamed Burkholderia species and, for the first time in South America, Cupriavidus taiwanensis. The sampling site had a strong influence on the diversity of the symbionts sampled, and the specific distributions of symbiotic populations between the soils were related to soil composition in some cases. Some alpha-rhizobial strains taxonomically close to Rhizobium endophyticum were also trapped in one soil, and these carried two copies of the nodA gene, a feature not previously reported. Phylogenies of nodA, nodC and nifH genes showed a monophyly of symbiotic genes for beta-rhizobia isolated from Mimosa spp., indicative of a long history of interaction between beta-rhizobia and Mimosa species. Based on their symbiotic gene phylogenies and legume hosts, B. tuberum was shown to contain two large biovars: one specific to the mimosoid genus Mimosa and one to South African papilionoid legumes.
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Haubensak KA, D’Antonio CM. The importance of nitrogen-fixation for an invader of a coastal California grassland. Biol Invasions 2010. [DOI: 10.1007/s10530-010-9904-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Distribution patterns of shrubby N-fixers and non-N fixers in an arid valley in Southwest China: implications for ecological restoration. Ecol Res 2010. [DOI: 10.1007/s11284-009-0685-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Vinuesa P, Rojas-Jiménez K, Contreras-Moreira B, Mahna SK, Prasad BN, Moe H, Selvaraju SB, Thierfelder H, Werner D. Multilocus sequence analysis for assessment of the biogeography and evolutionary genetics of four Bradyrhizobium species that nodulate soybeans on the asiatic continent. Appl Environ Microbiol 2008; 74:6987-96. [PMID: 18791003 PMCID: PMC2583495 DOI: 10.1128/aem.00875-08] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Accepted: 09/07/2008] [Indexed: 01/12/2023] Open
Abstract
A highly supported maximum-likelihood species phylogeny for the genus Bradyrhizobium was inferred from a supermatrix obtained from the concatenation of partial atpD, recA, glnII, and rpoB sequences corresponding to 33 reference strains and 76 bradyrhizobia isolated from the nodules of Glycine max (soybean) trap plants inoculated with soil samples from Myanmar, India, Nepal, and Vietnam. The power of the multigene approach using multiple strains per species was evaluated in terms of overall tree resolution and phylogenetic congruence, representing a practical and portable option for bacterial molecular systematics. Potential pitfalls of the approach are highlighted. Seventy-five of the isolates could be classified as B. japonicum type Ia (USDA110/USDA122-like), B. liaoningense, B. yuanmingense, or B. elkanii, whereas one represented a novel Bradyrhizobium lineage. Most Nepalese B. japonicum Ia isolates belong to a highly epidemic clone closely related to strain USDA110. Significant phylogenetic evidence against the monophyly of the of B. japonicum I and Ia lineages was found. Analysis of their DNA polymorphisms revealed high population distances, significant genetic differentiation, and contrasting population genetic structures, suggesting that the strains in the Ia lineage are misclassified as B. japonicum. The DNA polymorphism patterns of all species conformed to the expectations of the neutral mutation and population equilibrium models and, excluding the B. japonicum Ia lineage, were consistent with intermediate recombination levels. All species displayed epidemic clones and had broad geographic and environmental distribution ranges, as revealed by mapping climate types and geographic origins of the isolates on the species tree.
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Affiliation(s)
- Pablo Vinuesa
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México UNAM, Cuernavaca CP 62210, Morelos, México.
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