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Zhong C, Hu G, Hu C, Xu C, Zhang Z, Ning K. Comparative genomics analysis reveals genetic characteristics and nitrogen fixation profile of Bradyrhizobium. iScience 2024; 27:108948. [PMID: 38322985 PMCID: PMC10845061 DOI: 10.1016/j.isci.2024.108948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 09/12/2023] [Accepted: 01/15/2024] [Indexed: 02/08/2024] Open
Abstract
Bradyrhizobium is a genus of nitrogen-fixing bacteria, with some species producing nodules in leguminous plants. Investigations into Bradyrhizobium have recently revealed its substantial genetic resources and agricultural benefits, but a comprehensive survey of its genetic diversity and functional properties is lacking. Using a panel of various strains (N = 278), this study performed a comparative genomics analysis to anticipate genes linked with symbiotic nitrogen fixation. Bradyrhizobium's pan-genome consisted of 84,078 gene families, containing 824 core genes and 42,409 accessory genes. Core genes were mainly involved in crucial cell processes, while accessory genes served diverse functions, including nitrogen fixation and nodulation. Three distinct genetic profiles were identified based on the presence/absence of gene clusters related to nodulation, nitrogen fixation, and secretion systems. Most Bradyrhizobium strains from soil and non-leguminous plants lacked major nif/nod genes and were evolutionarily more closely related. These findings shed light on Bradyrhizobium's genetic features for symbiotic nitrogen fixation.
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Affiliation(s)
- Chaofang Zhong
- Key Laboratory of Wildlife Evolution and Conservation in Mountain Ecosystem of Guangxi, College of Environmental and Life Sciences, Nanning Normal University, Nanning 530001, China
| | - Gang Hu
- Key Laboratory of Wildlife Evolution and Conservation in Mountain Ecosystem of Guangxi, College of Environmental and Life Sciences, Nanning Normal University, Nanning 530001, China
| | - Cong Hu
- Key Laboratory of Wildlife Evolution and Conservation in Mountain Ecosystem of Guangxi, College of Environmental and Life Sciences, Nanning Normal University, Nanning 530001, China
| | - Chaohao Xu
- Key Laboratory of Wildlife Evolution and Conservation in Mountain Ecosystem of Guangxi, College of Environmental and Life Sciences, Nanning Normal University, Nanning 530001, China
| | - Zhonghua Zhang
- Key Laboratory of Wildlife Evolution and Conservation in Mountain Ecosystem of Guangxi, College of Environmental and Life Sciences, Nanning Normal University, Nanning 530001, China
| | - Kang Ning
- Key Laboratory of Molecular Biophysics of the Ministry of Education, Hubei Key Laboratory of Bioinformatics and Molecular-imaging, Department of Bioinformatics and Systems Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
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Abe JNA, Dhungana I, Nguyen NH. Legume-nodulating rhizobia are widespread in soils and plants across the island of O'ahu, Hawai'i. PLoS One 2023; 18:e0291250. [PMID: 37695782 PMCID: PMC10495000 DOI: 10.1371/journal.pone.0291250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 08/23/2023] [Indexed: 09/13/2023] Open
Abstract
Legumes and their interaction with rhizobia represent one of the most well-characterized symbioses that are widespread across both natural and agricultural environments. However, larger distribution patterns and host associations on isolated Pacific islands with many native and introduced hosts have not been well-documented. Here, we used molecular and culturing techniques to characterize rhizobia from soils and 24 native and introduced legume species on the island of O'ahu, Hawai'i. We chose two of these isolates to inoculate an endemic legume tree, Erythina sandwicensis to measure nodulation potentials and host benefits. We found that all rhizobia genera can be found in the soil, where only Cupriavidus was found at all sites, although at lower abundance relative to other more common genera such as Rhizobium (and close relatives), Bradyzhizobium, and Devosia. Bradyrhizobium was the most common nodulator of legumes, where the strain Bradyrhizobium sp. strain JA1 is a generalist capable of forming nodules on nine different host species, including two native species. In greenhouse nursery inoculations, the two different Bradyrhizobium strains successfully nodulate the endemic E. sandwicensis; both strains equally and significantly increased seedling biomass in nursery inoculations. Overall, this work provides a molecular-based framework in which to study potential native and introduced rhizobia on one of the most isolated archipelagos on the planet.
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Affiliation(s)
- Jonathan N. A. Abe
- Department of Tropical Plant and Soil Sciences, University of Hawaiʻi at Mānoa, Honolulu, HI, United States of America
| | - Ishwora Dhungana
- Department of Tropical Plant and Soil Sciences, University of Hawaiʻi at Mānoa, Honolulu, HI, United States of America
| | - Nhu H. Nguyen
- Department of Tropical Plant and Soil Sciences, University of Hawaiʻi at Mānoa, Honolulu, HI, United States of America
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Pulido-Suárez L, Notario Del Pino J, Díaz-Peña FJ, Perdomo-González A, González-Rodríguez ÁM, León-Barrios M. High Diversity of Bradyrhizobial Species Fix Nitrogen with Woody Legume Spartocytisus supranubius in a High Mountain Ecosystem. Microorganisms 2023; 11:1244. [PMID: 37317218 DOI: 10.3390/microorganisms11051244] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 05/02/2023] [Accepted: 05/05/2023] [Indexed: 06/16/2023] Open
Abstract
The symbiosis between rhizobia and legumes is of pivotal importance in nitrogen-poor ecosystems. Furthermore, as it is a specific process (most legumes only establish a symbiosis with certain rhizobia), it is of great interest to know which rhizobia are able to nodulate key legumes in a specific habitat. This study describes the diversity of the rhizobia that are able to nodulate the shrub legume Spartocytisus supranubius in the harsh environmental conditions of the high mountain ecosystem of Teide National Park (Tenerife). The diversity of microsymbionts nodulating S. supranubius was estimated from a phylogenetic analysis of root nodule bacteria isolated from soils at three selected locations in the park. The results showed that a high diversity of species of Bradyrhizobium and two symbiovars can nodulate this legume. Phylogenies of ribosomal and housekeeping genes showed these strains distributed into three main clusters and a few isolates on separate branches. These clusters consist of strains representing three new phylogenetic lineages of the genus Bradyrhizobium. Two of these lineages belong to the B. japonicum superclade, which we refer to as B. canariense-like and B. hipponense-like, as the type strains of these species are the closest species to our isolates. The third main group was clustered within the B. elkanii superclade and is referred to as B. algeriense-like as B. algeriense is its closest species. This is the first time that bradyrhizobia of the B. elkanii superclade have been reported for the canarian genista. Furthermore, our results suggest that these three main groups might belong to potential new species of the genus Bradyrhizobium. Analysis of the soil physicochemical properties of the three study sites showed some significant differences in several parameters, which, however, did not have a major influence on the distribution of bradyrhizobial genotypes at the different locations. The B. algeriense-like group had a more restrictive distribution pattern, while the other two lineages were detected in all of the soils. This suggests that the microsymbionts are well adapted to the harsh environmental conditions of Teide National Park.
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Affiliation(s)
- Laura Pulido-Suárez
- Department of Biochemistry, Microbiology, Genetics and Cellular Biology, University of La Laguna, 38200 San Cristóbal de La Laguna, Spain
| | - Jesús Notario Del Pino
- Department of Animal Biology, Soil Science and Geology, University of La Laguna, 38200 San Cristóbal de La Laguna, Spain
| | - Francisco J Díaz-Peña
- Department of Animal Biology, Soil Science and Geology, University of La Laguna, 38200 San Cristóbal de La Laguna, Spain
| | - Adolfo Perdomo-González
- Department of Animal Biology, Soil Science and Geology, University of La Laguna, 38200 San Cristóbal de La Laguna, Spain
| | - Águeda M González-Rodríguez
- Department of Botany, Ecology and Plant Physiology, University of La Laguna, 38200 San Cristóbal de La Laguna, Spain
| | - Milagros León-Barrios
- Department of Biochemistry, Microbiology, Genetics and Cellular Biology, University of La Laguna, 38200 San Cristóbal de La Laguna, Spain
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Denitrification by Bradyrhizobia under Feast and Famine and the Role of the bc1 Complex in Securing Electrons for N 2O Reduction. Appl Environ Microbiol 2023; 89:e0174522. [PMID: 36662572 PMCID: PMC9972998 DOI: 10.1128/aem.01745-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Rhizobia living as microsymbionts inside nodules have stable access to carbon substrates, but also must survive as free-living bacteria in soil where they are starved for carbon and energy most of the time. Many rhizobia can denitrify, thus switch to anaerobic respiration under low O2 tension using N-oxides as electron acceptors. The cellular machinery regulating this transition is relatively well known from studies under optimal laboratory conditions, while little is known about this regulation in starved organisms. It is, for example, not known if the strong preference for N2O- over NO3- reduction in bradyrhizobia is retained under carbon limitation. Here, we show that starved cultures of a Bradyrhizobium strain with respiration rates 1 to 18% of well-fed cultures reduced all available N2O before touching provided NO3-. These organisms, which carry out complete denitrification, have the periplasmic nitrate reductase NapA but lack the membrane-bound nitrate reductase NarG. Proteomics showed similar levels of NapA and NosZ (N2O reductase), excluding that the lack of NO3- reduction was due to low NapA abundance. Instead, this points to a metabolic-level phenomenon where the bc1 complex, which channels electrons to NosZ via cytochromes, is a much stronger competitor for electrons from the quinol pool than the NapC enzyme, which provides electrons to NapA via NapB. The results contrast the general notion that NosZ activity diminishes under carbon limitation and suggest that bradyrhizobia carrying NosZ can act as strong sinks for N2O under natural conditions, implying that this criterion should be considered in the development of biofertilizers. IMPORTANCE Legume cropped farmlands account for substantial N2O emissions globally. Legumes are commonly inoculated with N2-fixing bacteria, rhizobia, to improve crop yields. Rhizobia belonging to Bradyrhizobium, the microsymbionts of several economically important legumes, are generally capable of denitrification but many lack genes encoding N2O reductase and will be N2O sources. Bradyrhizobia with complete denitrification will instead act as sinks since N2O-reduction efficiently competes for electrons over nitrate reduction in these organisms. This phenomenon has only been demonstrated under optimal conditions and it is not known how carbon substrate limitation, which is the common situation in most soils, affects the denitrification phenotype. Here, we demonstrate that bradyrhizobia retain their strong preference for N2O under carbon starvation. The findings add basic knowledge about mechanisms controlling denitrification and support the potential for developing novel methods for greenhouse gas mitigation based on legume inoculants with the dual capacity to optimize N2 fixation and minimize N2O emission.
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Awuni GA, Reynolds DB, Dodds D, Denwar NN, Abdulai AL, Asungre PA, Yahaya I, Goldsmith PD. Lime, inoculum, and phosphorous input supplementation under rain-fed soybean in Ghana's northern savannas. FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 2023. [DOI: 10.3389/fsufs.2023.992644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
IntroductionRecent prices in soybean have spurred interest in motivating growers into input integration to improve yields across the northern savannas of Ghana. This requires more knowledge of input integration to increase soybean yield and profitability across production areas.Materials and methodA 3-yr study was conducted in three locations at Manga, Nyankpala, and Wa in Ghana's northern savanna to identify the best-yielding input combination under a rain-fed environment. The experiment used “Jenguma” soybean cultivar with lime, inoculum, and phosphorus in a 2 × 2 × 2 factorial arrangement with four replications. Eight treatment combinations (control included) were used to assess soybean yield, yield components, rain use efficiency, and economic profitability. The single-input application of lime (T1), inoculum (T2), and phosphorus (T4) was the low-input, lime × inoculum (T3), lime × phosphorus (T5), and (inoculum × phosphorus) (T6) as medium input, T7 (lime × inoculum × phosphorus) was high input, and a no-input treatment (control).ResultsThe soils were inherently low in fertility, and weather variability during the reproductive stages was a significant limiting factor to improving grain yield across locations. Grain yield was highest in 2017 at Manga and Nyankpala, but in 2019 at Wa. Except at Manga, grain yield and rain use efficiency (RUE) were highest in the high input system (T7). However, marginal net benefits (MNB) and marginal rate of returns (MRR) were highest in the low input system (T2) across locations. The low (T1) and medium (T3) input systems (except Nyankpala) were dominant for MNB and MRR due to the high cost of the lime product.DiscussionThese results suggest that smallholder farmers prefer low input (T2) with the least cost of production and the highest marginal net benefit and marginal rate of returns. Nevertheless, producers would have to evaluate their resource base and the cost of nutrient integration for sustainability.ConclusionThis paper recommends further studies on lime rates to determine profitability, lime's long-term (residual) effect, and the synergic impact of inoculum and phosphorus.
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Nzila A, Musa MM, Afuecheta E, Al-Thukair A, Sankaran S, Xiang L, Li QX. Benzo[A]Pyrene Biodegradation by Multiple and Individual Mesophilic Bacteria under Axenic Conditions and in Soil Samples. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:1855. [PMID: 36767220 PMCID: PMC9914810 DOI: 10.3390/ijerph20031855] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 12/29/2022] [Accepted: 01/04/2023] [Indexed: 06/18/2023]
Abstract
To date, only a handful of bacterial strains that can independently degrade and utilize benzo[a]pyrene (BaP) as the sole carbon source has been isolated and characterized. Here, three new bacterial strains-JBZ1A, JBZ2B, and JBZ5E-were isolated from contaminated soil and, using 16S rRNA sequencing, were identified as Brad rhizobium japonicum, Micrococcus luteus, and Bacillus cereus, respectively. The growth ability of each individual strain and a consortium of all strains in the presence of BaP (4-400 µmol·L-1, pH 7, 37 °C) was identified by the doubling time (dt). The results illustrate that dt decreased with increasing BaP concentrations for individual strains and the consortium. The optimum growth conditions of the consortium were 37 °C, 0.5% NaCl (w/v), and pH 7. Under these conditions, the degradation rate was 1.06 µmol·L-1·day-1, whereas that of individual strains ranged from 0.9 to 0.38 µmol·L-1·day-1. B. cereus had the strongest contribution to the consortium's activity, with a degradation rate of 0.9 µmol·L-1·day-1. The consortium could also remove BaP spiked with soil but at a lower rate (0.01 µmol L-1.day-1). High-performance liquid chromatography-high-resolution tandem mass spectrometry permitted the detection of the metabolites of these strains, and a biodegradation pathway is proposed.
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Affiliation(s)
- Alexis Nzila
- Department of Bioengineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
- Interdisciplinary Research Center for Membranes and Water Security, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
| | - Musa M. Musa
- Department of Chemistry, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
- Interdisciplinary Research Center for Refining and Advanced Chemicals, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
| | - Emmanuel Afuecheta
- Departments of Mathematics, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
| | - Assad Al-Thukair
- Department of Bioengineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
| | - Saravanan Sankaran
- Department of Bioengineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
| | - Lei Xiang
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Qing X. Li
- Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, Honolulu, HI 96822, USA
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Mortuza MF, Djedidi S, Ito T, Agake SI, Sekimoto H, Yokoyama T, Okazaki S, Ohkama-Ohtsu N. Genetic and Physiological Characterization of Soybean-Nodule-Derived Isolates from Bangladeshi Soils Revealed Diverse Array of Bacteria with Potential Bradyrhizobia for Biofertilizers. Microorganisms 2022; 10:2282. [PMID: 36422352 PMCID: PMC9698105 DOI: 10.3390/microorganisms10112282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 11/05/2022] [Accepted: 11/15/2022] [Indexed: 12/13/2023] Open
Abstract
Genetic and physiological characterization of bacteria derived from nodules of leguminous plants in the exploration of biofertilizer is of paramount importance from agricultural and environmental perspectives. Phylogenetic analysis of the 16S rRNA gene of 84 isolates derived from Bangladeshi soils revealed an unpredictably diverse array of nodule-forming and endosymbiotic bacteria-mostly belonging to the genus Bradyrhizobium. A sequence analysis of the symbiotic genes (nifH and nodD1) revealed similarities with the 16S rRNA gene tree, with few discrepancies. A phylogenetic analysis of the partial rrn operon (16S-ITS-23S) and multi-locus sequence analysis of atpD, glnII, and gyrB identified that the Bradyrhizobium isolates belonged to Bradyrhizobium diazoefficiens, Bradyrhizobium elkanii, Bradyrhizobium liaoningense and Bradyrhizobium yuanmingense species. In the pot experiment, several isolates showed better activity than B. diazoefficiens USDA110, and the Bho-P2-B2-S1-51 isolate of B. liaoningense showed significantly higher acetylene reduction activity in both Glycine max cv. Enrei and Binasoybean-3 varieties and biomass production increased by 9% in the Binasoybean-3 variety. Tha-P2-B1-S1-68 isolate of B. diazoefficiens significantly enhanced shoot length and induced 10% biomass production in Binasoybean-3. These isolates grew at 1-4% NaCl concentration and pH 4.5-10 and survived at 45 °C, making the isolates potential candidates for eco-friendly soybean biofertilizers in salty and tropical regions.
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Affiliation(s)
- Md Firoz Mortuza
- United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology (TUAT), Saiwai-cho 3-5-8, Fuchu-shi, Tokyo 183-8509, Japan
- Institute of Food and Radiation Biology, Atomic Energy Research Establishment, Bangladesh Atomic Energy Commission, Ganakbari, Savar, Dhaka 1207, Bangladesh
| | - Salem Djedidi
- Faculty of Agriculture, Tokyo University of Agriculture and Technology (TUAT), Saiwai-cho 3-5-8, Fuchu-shi, Tokyo 183-8509, Japan
| | - Takehiro Ito
- United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology (TUAT), Saiwai-cho 3-5-8, Fuchu-shi, Tokyo 183-8509, Japan
| | - Shin-ichiro Agake
- Institute of Global Innovation Research, Tokyo University of Agriculture and Technology (TUAT), Harumi-cho 3-8-1, Fuchu-shi, Tokyo 183-8509, Japan
| | - Hitoshi Sekimoto
- Faculty of Agriculture, Utsunomiya University, Utsunomiya-shi, Tochigi 321-8505, Japan
| | - Tadashi Yokoyama
- Institute of Agriculture, Tokyo University of Agriculture and Technology (TUAT), Saiwai-cho 3-5-8, Fuchu-shi, Tokyo 183-8509, Japan
- Faculty of Food and Agricultural Sciences, Fukushima University, Kanayagawa 1, Fukushima-shi, Fukushima 960-1248, Japan
| | - Shin Okazaki
- Institute of Agriculture, Tokyo University of Agriculture and Technology (TUAT), Saiwai-cho 3-5-8, Fuchu-shi, Tokyo 183-8509, Japan
| | - Naoko Ohkama-Ohtsu
- Institute of Global Innovation Research, Tokyo University of Agriculture and Technology (TUAT), Harumi-cho 3-8-1, Fuchu-shi, Tokyo 183-8509, Japan
- Institute of Agriculture, Tokyo University of Agriculture and Technology (TUAT), Saiwai-cho 3-5-8, Fuchu-shi, Tokyo 183-8509, Japan
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Castellano-Hinojosa A, Mora C, Strauss SL. Native Rhizobia Improve Plant Growth, Fix N 2, and Reduce Greenhouse Emissions of Sunnhemp More than Commercial Rhizobia Inoculants in Florida Citrus Orchards. PLANTS (BASEL, SWITZERLAND) 2022; 11:3011. [PMID: 36432740 PMCID: PMC9695096 DOI: 10.3390/plants11223011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 11/04/2022] [Accepted: 11/05/2022] [Indexed: 06/16/2023]
Abstract
Sunnhemp (Crotalaria juncea L.) is an important legume cover crop used in tree cropping systems, where there is increased interest by growers to identify rhizobia to maximize soil nitrogen (N) inputs. We aimed to isolate and identify native rhizobia and compare their capabilities with non-native rhizobia from commercial inoculants to fix atmospheric dinitrogen (N2), produce and reduce nitrous oxide (N2O), and improve plant growth. Phylogenetic analyses of sequences of the 16S rRNA and recA, atpD, and glnII genes showed native rhizobial strains belonged to Rhizobium tropici and the non-native strain to Bradyrhizobium japonicum. Plant nodulation tests, sequencing of nodC and nifH genes, and the acetylene-dependent ethylene production assay confirmed the capacity of all strains to nodulate sunnhemp and fix N2. Inoculation with native rhizobial strains resulted in significant increases in root and shoot weight and total C and N contents in the shoots, and showed greater N2-fixation rates and lower emissions of N2O compared to the non-native rhizobium. Our results suggest that native rhizobia improve plant growth, fix N2, and reduce greenhouse emissions of sunnhemp more than commercial rhizobia inoculants in Florida citrus orchards.
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Ferreira-Neto JRC, de Araújo FC, de Oliveira Silva RL, de Melo NF, Pandolfi V, Frosi G, de Lima Morais DA, da Silva MD, Rivas R, Santos MG, de Tarso Aidar S, Morgante CV, Benko-Iseppon AM. Dehydration response in Stylosanthes scabra: Transcriptional, biochemical, and physiological modulations. PHYSIOLOGIA PLANTARUM 2022; 174:e13821. [PMID: 36345266 DOI: 10.1111/ppl.13821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 10/22/2022] [Accepted: 11/01/2022] [Indexed: 06/16/2023]
Abstract
Stylosanthes scabra, popularly known as stylo, is native to the Brazilian Caatinga semiarid region and stands out as a drought-tolerant shrub forage crop. This work provides information about the plant response during the first 48 h of water deficit, followed by a rehydration treatment. Besides root transcriptomics data, 13 physiological or biochemical parameters were scrutinized. Additionally, RNA-Seq annotated transcripts not associated with the "Viridiplantae" clade were taxonomically categorized. It was found that S. scabra quickly perceives and recovers from the oscillations of the imposed water regime. Physiologically, mechanisms that minimize evapotranspiration or protect the photosynthetic apparatus stood out. Biochemically, it was found that the root tissue invests in synthesizing compounds that can act as osmolytes (proline and sugars), emphasizing the importance of osmoregulation to water deficit acclimation. Consistently, transcriptome and qPCR analyses showed that a set of enriched biological processes with upregulated (UR) transcripts were involved in protective functions against reactive oxygen species or encoding enzymes of important metabolic pathways, which might contribute to S. scabra response to water deficit. Additionally, several UR kinases and transcription factors were identified. Finally, in an innovative approach, some naturally occurring microbial groups (such as Schizosaccharomyces, Bradyrhizobium, etc.) were identified in the S. scabra roots. This study reveals insights into the physiological, biochemical, and molecular mechanisms underlying the S. scabra response to water deficit and provides candidate genes that may be useful in developing drought-tolerant crop varieties through biotechnological applications.
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Affiliation(s)
- José Ribamar Costa Ferreira-Neto
- Laboratório de Genética e Biotecnologia Vegetal, Departamento de Genética, Centro de Biociências, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Flávia Czekalski de Araújo
- Laboratório de Genética e Biotecnologia Vegetal, Departamento de Genética, Centro de Biociências, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Roberta Lane de Oliveira Silva
- Laboratório de Genética e Biotecnologia Vegetal, Departamento de Genética, Centro de Biociências, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | | | - Valesca Pandolfi
- Laboratório de Genética e Biotecnologia Vegetal, Departamento de Genética, Centro de Biociências, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Gabriella Frosi
- Départament de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | | | - Manassés Daniel da Silva
- Laboratório de Genética Molecular, Departamento de Genética, Centro de Biociências, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Rebeca Rivas
- Laboratório de Genética Molecular, Departamento de Genética, Centro de Biociências, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Mauro Guida Santos
- Laboratório de Fisiologia Vegetal, Departamento de Botânica, Centro de Biociências, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Saulo de Tarso Aidar
- Empresa Brasileira de Pesquisa Agropecuária (SEMIÁRIDO), Petrolina, Pernambuco, Brazil
| | | | - Ana Maria Benko-Iseppon
- Laboratório de Genética e Biotecnologia Vegetal, Departamento de Genética, Centro de Biociências, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
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Bitire TD, Abberton M, Oyatomi O, Babalola OO. Effect of Bradyrhizobium japonicum Strains and Inorganic Nitrogen Fertilizer on the Growth and Yield of Bambara Groundnut (Vigna subterranea (L.) Verdc) Accessions. FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 2022. [DOI: 10.3389/fsufs.2022.913239] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
This study was set up to compare the inoculation of Bradyrhizobium japonicum strains and the application of nitrogen (N) fertilizers (urea with 46% nitrogen) on the growth and yield of Bambara groundnut accessions. The study results suggest that the benefits of Bradyrhizobium japonicum (B. japonicum) strain inoculation are greater and that the strain could reduce reliance and the excess amount spent by farmers to procure inorganic fertilizers and avoid the negative effect of N fertilizer on the environment after its use. Field studies were conducted in two different geographical locations, in Ibadan (Ib) and Ikenne (Ik), Nigeria, during the rainy season between August and December in 2019 and 2020. The experiment was arranged in a randomized complete block design (RCBD) in both locations and seasons and was replicated three times, with each block representing each replicate. It had a 10 × 6 factorial arrangement with one block holding the 10 accessions of Bambara groundnut inoculated with four B. japonicum strains. The second block had N fertilizer application and the third control block was without inoculation or fertilizer application. The 10 accessions of Bambara groundnut used in the study were as follows: TVSu-378, TVSu-506, TVSu-787, TVSu-1606, TVSu-1698, TVSu-1739, TVSu-710, TVSu-365, TVSu-475, and TVSu-305. Six seeds of each accession were coated with each of the four B. japonicum strains, namely, FA3, USDA110, IRJ2180A, and RACA6, before planting them in the field in both locations during the rainy season. In the next block, urea as N fertilizer (46% nitrogen) was applied to the uninoculated seedlings of accessions of Bambara groundnut 2 weeks after planting (WAP). The third block was the control with zero inoculation and zero fertilizer application. Data collected were subjected to an analysis of variance and mean and were separated using Duncan's Multiple Range Test (DMRT) at a p > 0.05 level of probability. It was found that FA3 inoculation significantly enhanced the growth traits of the accessions than other strains and N fertilizer application. In both locations and seasons, at 7 weeks after planting (WAP) and 12 WAP, plant height (19.54 and 22.71 cm), number of branches (33.63 and 62.77), number of leaves (116.54 and 209.25), terminal leaf length (5.62 and 6.00 cm), and width (2.09 and 2.56 cm) were recorded. The yield and yield components recorded at harvest were as follows: pod length (13.27 cm), pod width (9.08 mm), seed length (9.39 mm), seed width (6.92 mm), weight of 100 seeds (56.85 g), and yield/ha (750.72 kg). The yield and yield components were also significantly influenced by the inoculation of FA3 and RACA6 than other inoculated strains and N fertilizer application in both locations and seasons.
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Wekesa C, Jalloh AA, Muoma JO, Korir H, Omenge KM, Maingi JM, Furch ACU, Oelmüller R. Distribution, Characterization and the Commercialization of Elite Rhizobia Strains in Africa. Int J Mol Sci 2022; 23:ijms23126599. [PMID: 35743041 PMCID: PMC9223902 DOI: 10.3390/ijms23126599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/07/2022] [Accepted: 06/09/2022] [Indexed: 02/04/2023] Open
Abstract
Grain legumes play a significant role in smallholder farming systems in Africa because of their contribution to nutrition and income security and their role in fixing nitrogen. Biological Nitrogen Fixation (BNF) serves a critical role in improving soil fertility for legumes. Although much research has been conducted on rhizobia in nitrogen fixation and their contribution to soil fertility, much less is known about the distribution and diversity of the bacteria strains in different areas of the world and which of the strains achieve optimal benefits for the host plants under specific soil and environmental conditions. This paper reviews the distribution, characterization, and commercialization of elite rhizobia strains in Africa.
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Affiliation(s)
- Clabe Wekesa
- Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular Botany and Plant Physiology, Friedrich-Schiller-University Jena, Dornburger Str. 159, 07743 Jena, Germany; (C.W.); (K.M.O.); (A.C.U.F.)
| | - Abdul A. Jalloh
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, Nairobi 00100, Kenya;
| | - John O. Muoma
- Department of Biological Sciences, Masinde Muliro University of Science and Technology, P.O. Box 190, Kakamega 50100, Kenya;
| | - Hezekiah Korir
- Crops, Horticulture and Soils Department, Egerton University, P.O. Box 536, Egerton 20115, Kenya;
| | - Keziah M. Omenge
- Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular Botany and Plant Physiology, Friedrich-Schiller-University Jena, Dornburger Str. 159, 07743 Jena, Germany; (C.W.); (K.M.O.); (A.C.U.F.)
| | - John M. Maingi
- Department of Biochemistry, Microbiology and Biotechnology, Kenyatta University, P.O. Box 43844, Nairobi 00100, Kenya;
| | - Alexandra C. U. Furch
- Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular Botany and Plant Physiology, Friedrich-Schiller-University Jena, Dornburger Str. 159, 07743 Jena, Germany; (C.W.); (K.M.O.); (A.C.U.F.)
| | - Ralf Oelmüller
- Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular Botany and Plant Physiology, Friedrich-Schiller-University Jena, Dornburger Str. 159, 07743 Jena, Germany; (C.W.); (K.M.O.); (A.C.U.F.)
- Correspondence: ; Tel.: +49-3641949232
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Adjei JA, Aserse AA, Yli-Halla M, Ahiabor BDK, Abaidoo RC, Lindstrom K. Phylogenetically diverse Bradyrhizobium genospecies nodulate Bambara groundnut (Vigna subterranea L. Verdc) and soybean (Glycine max L. Merril) in the northern savanna zones of Ghana. FEMS Microbiol Ecol 2022; 98:fiac043. [PMID: 35404419 PMCID: PMC9329091 DOI: 10.1093/femsec/fiac043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 03/30/2022] [Accepted: 04/08/2022] [Indexed: 11/25/2022] Open
Abstract
A total of 102 bacterial strains isolated from nodules of three Bambara groundnut and one soybean cultivars grown in nineteen soil samples collected from northern Ghana were characterized using multilocus gene sequence analysis. Based on a concatenated sequence analysis (glnII-rpoB-recA-gyrB-atpD-dnaK), 54 representative strains were distributed in 12 distinct lineages, many of which were placed mainly in the Bradyrhizobium japonicum and Bradyrhizobium elkanii supergroups. Twenty-four of the 54 representative strains belonged to seven putative novel species, while 30 were conspecific with four recognized Bradyrhizobium species. The nodA phylogeny placed all the representative strains in the cosmopolitan nodA clade III. The strains were further separated in seven nodA subclusters with reference strains mainly of African origin. The nifH phylogeny was somewhat congruent with the nodA phylogeny, but both symbiotic genes were mostly incongruent with the core housekeeping gene phylogeny indicating that the strains acquired their symbiotic genes horizontally from distantly related Bradyrhizobium species. Using redundancy analysis, the distribution of genospecies was found to be influenced by the edaphic factors of the respective sampling sites. In general, these results mainly underscore the high genetic diversity of Bambara groundnut-nodulating bradyrhizobia in Ghanaian soils and suggest a possible vast resource of adapted inoculant strains.
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Affiliation(s)
- Josephine A Adjei
- Department of Crop and Soil Sciences, Faculty of Agriculture, Kwame Nkrumah University of Science and Technology, PMB, Kumasi, Ghana
- Faculty of Biological and Environmental Sciences, University of Helsinki, FIN-00014 Helsinki, Finland
- Council for Scientific and Industrial Research, Savanna Agricultural Research Institute, PO Box 52, Tamale, Ghana
| | - Aregu A Aserse
- Faculty of Biological and Environmental Sciences, University of Helsinki, FIN-00014 Helsinki, Finland
| | - Markku Yli-Halla
- Department of Agricultural Sciences, University of Helsinki, FIN-00014 Helsinki, Finland
| | - Benjamin D K Ahiabor
- Council for Scientific and Industrial Research, Savanna Agricultural Research Institute, PO Box 52, Tamale, Ghana
| | - Robert C Abaidoo
- Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology, PMB, Kumasi, Ghana
- International Institute of Tropical Agriculture, PMB 5320, Ibadan, Nigeria
| | - Kristina Lindstrom
- Faculty of Biological and Environmental Sciences, University of Helsinki, FIN-00014 Helsinki, Finland
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Sun L, Zhang Z, Dong X, Tang Z, Ju B, Du Z, Wang E, Xie Z. Bradyrhizobium aeschynomenes sp. nov., a root and stem nodule microsymbiont of Aeschynomene indica. Syst Appl Microbiol 2022; 45:126337. [DOI: 10.1016/j.syapm.2022.126337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 05/15/2022] [Accepted: 05/23/2022] [Indexed: 10/18/2022]
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Bender FR, Nagamatsu ST, Delamuta JRM, Ribeiro RA, Nogueira MA, Hungria M. Genetic variation in symbiotic islands of natural variant strains of soybean Bradyrhizobium japonicum and Bradyrhizobium diazoefficiens differing in competitiveness and in the efficiency of nitrogen fixation. Microb Genom 2022; 8:000795. [PMID: 35438622 PMCID: PMC9453064 DOI: 10.1099/mgen.0.000795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Accepted: 02/07/2022] [Indexed: 11/18/2022] Open
Abstract
Soybean is the most important legume cropped worldwide and can highly benefit from the biological nitrogen fixation (BNF) process. Brazil is recognized for its leadership in the use of inoculants and two strains, Bradyrhizobium japonicum CPAC 15 (=SEMIA 5079) and Bradyrhizobium diazoefficiens CPAC 7 (=SEMIA 5080) compose the majority of the 70 million doses of soybean inoculants commercialized yearly in the country. We studied a collection of natural variants of these two strains, differing in properties of competitiveness and efficiency of BNF. We sequenced the genomes of the parental strain SEMIA 566 of B. japonicum, of three natural variants of this strain (S 204, S 340 and S 370), and compared with another variant of this group, strain CPAC 15. We also sequenced the genome of the parental strain SEMIA 586 of B. diazoefficiens, of three natural variants of this strain (CPAC 390, CPAC 392 and CPAC 394) and compared with the genome of another natural variant, strain CPAC 7. As the main genes responsible for nodulation (nod, noe, nol) and BNF (nif, fix) in soybean Bradyrhizobium are located in symbiotic islands, our objective was to identify genetic variations located in this region, including single nucleotide polymorphisms (SNPs) and insertions and deletions (indels), that could be potentially related to their different symbiotic phenotypes. We detected 44 genetic variations in the B. japonicum strains and three in B. diazoefficiens. As the B. japonicum strains have gone through a longer period of adaptation to the soil, the higher number of genetic variations could be explained by survival strategies under the harsh environmental conditions of the Brazilian Cerrado biome. Genetic variations were detected in genes enconding proteins such as a dephospho-CoA kinase, related to the CoA biosynthesis; a glucosamine-fructose-6-phosphate aminotransferase, key regulator of the hexosamine biosynthetic pathway; a LysR family transcriptional regulator related to nodulation genes; and NifE and NifS proteins, directly related to the BNF process. We suggest potential genetic variations related to differences in the symbiotic phenotypes.
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Affiliation(s)
- Flavia Raquel Bender
- Department of Biotechnology, Universidade Estadual de Londrina, C.P. 10011, 86057-970 Londrina, Paraná, Brazil
- Soil Biotechnology Laboratory, Embrapa Soja, C.P. 4006, 86085-981, Londrina-PR, Brazil
| | - Sheila Tiemi Nagamatsu
- Division of Human Genetics, Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Jakeline Renata Marçon Delamuta
- Soil Biotechnology Laboratory, Embrapa Soja, C.P. 4006, 86085-981, Londrina-PR, Brazil
- CNPq, SHIS QI 1 Conjunto B, Blocos A, B, C e D, Lago Sul, 71605-001, Brasília, Federal District, Brazil
| | - Renan Augusto Ribeiro
- CNPq, SHIS QI 1 Conjunto B, Blocos A, B, C e D, Lago Sul, 71605-001, Brasília, Federal District, Brazil
| | - Marco Antonio Nogueira
- Soil Biotechnology Laboratory, Embrapa Soja, C.P. 4006, 86085-981, Londrina-PR, Brazil
- CNPq, SHIS QI 1 Conjunto B, Blocos A, B, C e D, Lago Sul, 71605-001, Brasília, Federal District, Brazil
| | - Mariangela Hungria
- Department of Biotechnology, Universidade Estadual de Londrina, C.P. 10011, 86057-970 Londrina, Paraná, Brazil
- Soil Biotechnology Laboratory, Embrapa Soja, C.P. 4006, 86085-981, Londrina-PR, Brazil
- CNPq, SHIS QI 1 Conjunto B, Blocos A, B, C e D, Lago Sul, 71605-001, Brasília, Federal District, Brazil
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Dlamini ST, Jaiswal SK, Mohammed M, Dakora FD. Studies of Phylogeny, Symbiotic Functioning and Ecological Traits of Indigenous Microsymbionts Nodulating Bambara Groundnut (Vigna subterranea L. Verdc) in Eswatini. MICROBIAL ECOLOGY 2021; 82:688-703. [PMID: 33606087 DOI: 10.1007/s00248-021-01684-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 01/06/2021] [Indexed: 06/12/2023]
Abstract
Rhizobial microsymbionts of grain legumes are ubiquitous in soils and exhibit a wide range of diversity with respect to colony morphology, genetic variability, biochemical characteristics, and phylogenetic relationships. This study assessed the phylogenetic positions of rhizobial microsymbionts of Bambara groundnut from Eswatini exhibiting variations in morpho-physiology, adaptive characteristics, and N2-fixing efficiency. The isolates' ERIC-PCR profiles revealed the presence of high genetic variation among them. These test isolates also exhibited differences in pH tolerance and IAA production. Multilocus sequence analysis based on the 16S rRNA, atpD, glnII, gyrB, and recA gene sequences of representative test isolates closely aligned them to the type strains of Bradyrhizobium arachidis, B. manausense, B. guangdongense, B. elkanii, and B. pachyrhizi. However, some isolates showed a high divergence from the known reference type strains, indicating that they may represent species yet to be properly characterized and described. Functional characterization in the glasshouse revealed that most of the isolates from the contrasting Agro-ecologies of Eswatini were efficient in N2 fixation, and therefore elicited greater stomatal conductance and photosynthetic rates in the homologous Bambara groundnut. Of the 75 isolates tested, 51% were more effective than the commercial Bradyrhizobium sp. strain CB756, with relative symbiotic effectiveness ranging from 138 to 308%. The findings of this study indicated that the analysis of housekeeping genes and functional traits of Bambara-nodulating microsymbionts can provide a clear view for understanding and predicting rhizobial community structure across environmental gradients.
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Affiliation(s)
- Sibusiso T Dlamini
- Department of Crop Sciences, Tshwane University of Technology, Pretoria, South Africa
| | - Sanjay K Jaiswal
- Department of Chemistry, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa.
| | - Mustapha Mohammed
- Department of Crop Sciences, Tshwane University of Technology, Pretoria, South Africa
- Department of Chemistry, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa
| | - Felix D Dakora
- Department of Chemistry, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa.
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Gnangui SLE, Fossou RK, Ebou A, Amon CER, Koua DK, Kouadjo CGZ, Cowan DA, Zézé A. The Rhizobial Microbiome from the Tropical Savannah Zones in Northern Côte d'Ivoire. Microorganisms 2021; 9:microorganisms9091842. [PMID: 34576737 PMCID: PMC8472840 DOI: 10.3390/microorganisms9091842] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 08/17/2021] [Accepted: 08/21/2021] [Indexed: 01/04/2023] Open
Abstract
Over the past decade, many projects have been initiated worldwide to decipher the composition and function of the soil microbiome, including the African Soil Microbiome (AfSM) project that aims at providing new insights into the presence and distribution of key groups of soil bacteria from across the African continent. In this national study, carried out under the auspices of the AfSM project, we assessed the taxonomy, diversity and distribution of rhizobial genera in soils from the tropical savannah zones in Northern Côte d’Ivoire. Genomic DNA extracted from seven sampled soils was analyzed by sequencing the V4-V5 variable region of the 16S rDNA using Illumina’s MiSeq platform. Subsequent bioinformatic and phylogenetic analyses showed that these soils harbored 12 out of 18 genera of Proteobacteria harboring rhizobia species validly published to date and revealed for the first time that the Bradyrhizobium genus dominates in tropical savannah soils, together with Microvirga and Paraburkholderia. In silico comparisons of different 16S rRNA gene variable regions suggested that the V5-V7 region could be suitable for differentiating rhizobia at the genus level, possibly replacing the use of the V4-V5 region. These data could serve as indicators for future rhizobial microbiome explorations and for land-use decision-making.
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Affiliation(s)
- Sara Laetitia Elphège Gnangui
- Laboratoire de Biotechnologies Végétale et Microbienne (LBVM), Unité Mixte de Recherche et d’Innovation en Sciences Agronomiques et Génie Rural, Institut National Polytechnique Felix Houphouët-Boigny, Yamoussoukro 1093, Côte d’Ivoire; (S.L.E.G.); (A.E.); (C.E.R.A.); (A.Z.)
| | - Romain Kouakou Fossou
- Laboratoire de Biotechnologies Végétale et Microbienne (LBVM), Unité Mixte de Recherche et d’Innovation en Sciences Agronomiques et Génie Rural, Institut National Polytechnique Felix Houphouët-Boigny, Yamoussoukro 1093, Côte d’Ivoire; (S.L.E.G.); (A.E.); (C.E.R.A.); (A.Z.)
- Correspondence:
| | - Anicet Ebou
- Laboratoire de Biotechnologies Végétale et Microbienne (LBVM), Unité Mixte de Recherche et d’Innovation en Sciences Agronomiques et Génie Rural, Institut National Polytechnique Felix Houphouët-Boigny, Yamoussoukro 1093, Côte d’Ivoire; (S.L.E.G.); (A.E.); (C.E.R.A.); (A.Z.)
- Équipe Bioinformatique, Département de Formation et de Recherche Agriculture et Ressources Animales, Institut National Polytechnique Félix Houphouët-Boigny, Yamoussoukro 1313, Côte d’Ivoire;
| | - Chiguié Estelle Raïssa Amon
- Laboratoire de Biotechnologies Végétale et Microbienne (LBVM), Unité Mixte de Recherche et d’Innovation en Sciences Agronomiques et Génie Rural, Institut National Polytechnique Felix Houphouët-Boigny, Yamoussoukro 1093, Côte d’Ivoire; (S.L.E.G.); (A.E.); (C.E.R.A.); (A.Z.)
| | - Dominique Kadio Koua
- Équipe Bioinformatique, Département de Formation et de Recherche Agriculture et Ressources Animales, Institut National Polytechnique Félix Houphouët-Boigny, Yamoussoukro 1313, Côte d’Ivoire;
| | - Claude Ghislaine Zaka Kouadjo
- Laboratoire Central de Biotechnologies, Centre National de la Recherche Agronomique, 01 Abidjan 1740, Côte d’Ivoire;
| | - Don A. Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa;
| | - Adolphe Zézé
- Laboratoire de Biotechnologies Végétale et Microbienne (LBVM), Unité Mixte de Recherche et d’Innovation en Sciences Agronomiques et Génie Rural, Institut National Polytechnique Felix Houphouët-Boigny, Yamoussoukro 1093, Côte d’Ivoire; (S.L.E.G.); (A.E.); (C.E.R.A.); (A.Z.)
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Development of an Illumina-based analysis method to study bradyrhizobial population structure-case study on nitrogen-fixing rhizobia associating with cowpea or peanut. Appl Microbiol Biotechnol 2021; 105:6943-6957. [PMID: 34453562 DOI: 10.1007/s00253-021-11525-2] [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: 02/16/2021] [Revised: 08/04/2021] [Accepted: 08/07/2021] [Indexed: 10/20/2022]
Abstract
Bradyrhizobia are Gram-negative soil bacteria that regroup a growing number of species. They are widespread in nature and recovered from various biomes that may be explained by a high genetic diversity in this genus. Among the numerous metabolic properties they can harbor, the nitrogen fixation resulting from the association with plants among which important crop legumes (soya bean, peanut, cowpea …) is of great interest, notably in a context of sustainable development. Metabarcoding is widely applied to study biodiversity from complex microbial communities. Here, we demonstrate that using a new species-specific and highly polymorphic 16S-23S rRNA intergenic spacer barcode, we could rapidly estimate the diversity of bradyrhizobial populations that associate with cowpea and peanut plants, two crop legumes of major interest in Senegal. Application of the method on indigenous bradyrhizobia associated with peanut and cowpea grown in soils collected in the center of the peanut basin shows that Bradyrhizobium vignae is a dominant symbiont. We also showed that the two plant species associate with distinct community profiles and that strains introduced by inoculation significantly modified the population structure with these two plants suggesting that application of elite strains as inoculants may well ensure optimized symbiotic performance. This approach may further be used to study the diversity of bradyrhizobia from contrasting agro-eco-climatic zones, to test whether the plant genotype influences the association outputs as well as to estimate the competitiveness for nodule occupancy and the fate of elite strains inoculated in the field.Key points• An amplicon sequencing approach targeting the Bradyrhizobium genus was developed.• Diversity of cowpea and peanut bradyrhizobia from cultivated soils was identified.• The method is well suited to test the competitiveness of defined Bradyrhizobium inoculants.
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Simbine MG, Mohammed M, Jaiswal SK, Dakora FD. Functional and genetic diversity of native rhizobial isolates nodulating cowpea (Vigna unguiculata L. Walp.) in Mozambican soils. Sci Rep 2021; 11:12747. [PMID: 34140555 PMCID: PMC8211668 DOI: 10.1038/s41598-021-91889-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 05/26/2021] [Indexed: 02/05/2023] Open
Abstract
Identification and symbiotic characterization of indigenous rhizobial isolates are the basis for inoculant formulations needed for sustainable grain legume production. This study screened for morpho-genetic diversity of indigenous cowpea nodulating rhizobia in farmers' fields across two contrasting agroecological zones of Northern Mozambique. The photosynthetic function induced by the isolates in their homologous cowpea was assessed. The results showed high genetic variability among the isolates based on morphology and ERIC-PCR fingerprinting. The trap cowpea genotype did not influence the diversity of isolates collected from the two different agroecologies, suggesting that the cowpea-rhizobia compatibility may be conserved at species level. Phylogenetic analysis of the 16S rRNA gene assigned representative rhizobial isolates to species in the Bradyrhizobium and Rhizobium genera, with some isolates showing high divergence from the known reference type strains. The isolates from both agroecologies highly varied in the number and biomass of nodules induced in the homologous cowpea, resulting in variable plant growth and photosynthetic activities. A total of 72% and 83% of the isolates collected from the agroecological zones 7 and 8 were respectively classified as highly effective candidates with > 80% relative effectiveness compared to plants fertilized with nitrate, indicating that elite native strains populated the studied soils. Moreover, the top 25% of high N2-fixing isolates from the two agroecologies recorded relative effectiveness ranging from 115 to 154%, values higher than the effectiveness induced by the commercial Bradyrhizobium sp. strain CB756. These strains are considered as having potential for use in inoculant formulations. However, future studies should be done to assess the ecologically adaptive traits and symbiotic performance under field conditions.
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Affiliation(s)
- Margarida G. Simbine
- grid.412810.e0000 0001 0109 1328Department of Crop Sciences, Tshwane University of Technology, Private Bag X680, Pretoria, 0001 South Africa
| | - Mustapha Mohammed
- grid.412810.e0000 0001 0109 1328Department of Crop Sciences, Tshwane University of Technology, Private Bag X680, Pretoria, 0001 South Africa ,grid.442305.40000 0004 0441 5393Department of Crop Science, University for Development Studies, P.O. Box TL1882, Tamale, Ghana ,grid.412810.e0000 0001 0109 1328Department of Chemistry, Tshwane University of Technology, Arcadia campus, 175 Nelson Mandela Drive, Private Bag X680, Pretoria, 0001 South Africa
| | - Sanjay K. Jaiswal
- grid.412810.e0000 0001 0109 1328Department of Chemistry, Tshwane University of Technology, Arcadia campus, 175 Nelson Mandela Drive, Private Bag X680, Pretoria, 0001 South Africa
| | - Felix D. Dakora
- grid.412810.e0000 0001 0109 1328Department of Chemistry, Tshwane University of Technology, Arcadia campus, 175 Nelson Mandela Drive, Private Bag X680, Pretoria, 0001 South Africa
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Gitonga NM, Njeru EM, Cheruiyot R, Maingi JM. Genetic and Morphological Diversity of Indigenous Bradyrhizobium Nodulating Soybean in Organic and Conventional Family Farming Systems. FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 2021. [DOI: 10.3389/fsufs.2020.606618] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Organic farming systems are gaining popularity as agronomically and environmentally sound soil management strategies with potential to enhance soil microbial diversity and fertility, environmental quality and sustainable crop production. This work aimed at understanding the effect of organic and conventional farming on the diversity of soybean nodulating bradyrhizobia species. Field trapping of indigenous soybean Bradyrhizobium was done by planting promiscuous soybeans varieties SB16 and SC squire as well as non-promiscuous Gazelle in three organic and three conventional farms in Tharaka-Nithi County of Kenya. After 45 days of growth, 108 nodule isolates were obtained from the soybean nodules and placed into 13 groups based on their morphological characteristics. Genetic diversity was done by polymerase chain reaction (PCR) targeting 16S rDNA gene using universal primers P5-R and P3-F and sequencing was carried out using the same primer. High morphological and genetic diversity of the nodule isolates was observed in organic farms as opposed to conventional farms. There was little or no genetic differentiation between the nodule isolates from the different farms with the highest molecular variation (91.12%) being partitioned within populations as opposed to among populations (8.88%). All the isolates were identified as bradyrhizobia with close evolutionary ties with Bradyrhizobium japonicum and Bradyrhizobium yuanminense. Organic farming systems favor the proliferation of bradyrhizobia species and therefore a suitable environmentally friendly alternative for enhancing soybean production.
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do Nascimento TR, Sena PTS, Oliveira GS, da Silva TR, Dias MAM, de Freitas ADS, Martins LMV, Fernandes-Júnior PI. Co-inoculation of two symbiotically efficient Bradyrhizobium strains improves cowpea development better than a single bacterium application. 3 Biotech 2021; 11:4. [PMID: 33269188 DOI: 10.1007/s13205-020-02534-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 10/29/2020] [Indexed: 12/30/2022] Open
Abstract
The co-inoculation of Bradyrhizobium with other non-bradyrhizobial strains was already assessed on cowpea, but the co-inoculation of two Bradyrhizobium strains was not tested up to now. This study aimed to evaluate the cowpea growth, N accumulation, and Bradyrhizobium competitiveness of the elite strain B. pachyrhizi BR 3262 when co-inoculated with other efficient Bradyrhizobium from the Brazilian semiarid region. Three potted-plant experiments were carried out. In the first assay, 35 efficient Bradyrhizobium isolates obtained from the semiarid region of Brazil were co-inoculated with the elite strains B. pachyrhizi BR 3262. The experiment was conducted in gnotobiotic conditions. The plant growth, nodulation, N nutritional variables, and nodular occupation were assessed. Under gnotobiotic and non-sterile soil conditions, ten selected bacteria plus the elite strain B. yuanmingense BR 3267 were used at the second and third experiments, respectively. The cowpea was inoculated with the 11 bacteria individually or co-inoculated with BR 3262. The plant growth and N nutritional variables were assessed. A double-layer medium spot method experiment was conducted to evaluate the interaction among the co-inoculated strains in standard and diluted YMA media. The co-inoculation treatments showed the best efficiency when compared to the treatments inoculated solely with BR 3262. This strain occupied a low amount of cowpea nodules ranging from 5 to 67.5%. The treatments with lower BR 3262 nodule occupancy showed the best results for the shoot nitrogen accumulation. The culture experiment showed that four bacteria inhibited the growth of BR 3262. In contrast, seven strains from the soils of Brazilian semiarid region were benefited by the previous inoculation of this strain. In the second and third experiments, the results indicated that all 11 co-inoculated treatments were more efficient than the single inoculation, proofing the best performance of the dual inoculation of Bradyrhizobium on cowpea.
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Affiliation(s)
- Tailane Ribeiro do Nascimento
- Departamento de Tecnologia e Ciências Sociais, Universidade do Estado da Bahia, R. Edgard Chastinet, s/n, Juazeiro, BA Brazil
| | - Pâmella Thalita Souza Sena
- Departamento de Tecnologia e Ciências Sociais, Universidade do Estado da Bahia, R. Edgard Chastinet, s/n, Juazeiro, BA Brazil
| | - Gilmar Silva Oliveira
- Central Acadêmica, Universidade Estadual da Paraíba, R. Baraúnas 351, Campina Grande, PB Brazil
| | - Thaise Rosa da Silva
- Colegiado de Farmácia, Universidade Federal do Vale do São Francisco, Av. José de Sá Maniçoba, s/n, Petrolina, PE Brazil
| | - Marcos André Moura Dias
- Colegiado de Farmácia, Universidade Federal do Vale do São Francisco, Av. José de Sá Maniçoba, s/n, Petrolina, PE Brazil
| | | | - Lindete Míria Vieira Martins
- Departamento de Tecnologia e Ciências Sociais, Universidade do Estado da Bahia, R. Edgard Chastinet, s/n, Juazeiro, BA Brazil
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Wang C, Masoudi A, Wang M, Yang J, Shen R, Man M, Yu Z, Liu J. Community structure and diversity of the microbiomes of two microhabitats at the root-soil interface: implications of meta-analysis of the root-zone soil and root endosphere microbial communities in Xiong'an New Area. Can J Microbiol 2020; 66:605-622. [PMID: 32526152 DOI: 10.1139/cjm-2020-0061] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The diversity of the microbial compositions of the root-zone soil (the rhizosphere-surrounding soil) and root endosphere (all inner root tissues) of Pinus tabulaeformis Carr. and Ginkgo biloba L. were evaluated in Xiong'an New Area using high-throughput sequencing; the influence of the soil edaphic parameters on microbial community compositions was also evaluated. Our results showed that both the taxonomic and phylogenetic diversities of the root endosphere were lower than those of the root-zone soil, but the variation in the endosphere microbial community structure was remarkably higher than that of the root-zone soil. Spearman correlation analysis showed that the soil organic matter, total nitrogen, total phosphate, total potassium, ratio of carbon to nitrogen, and pH significantly explained the α-diversity of the bacterial community and that total nitrogen differentially contributed to the α-diversity of the fungal community. Variation partitioning analysis showed that plant species had a greater influence on microbial composition variations than did any other soil property, although soil chemical parameters explained more variation when integrated. Together, our results suggest that both plant species and soil chemical parameters played a critical role in shaping the microbial community composition.
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Affiliation(s)
- Can Wang
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, P.R. China
| | - Abolfazl Masoudi
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, P.R. China
| | - Min Wang
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, P.R. China
| | - Jia Yang
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, P.R. China
| | - Ruowen Shen
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, P.R. China
| | - Meng Man
- Library of Hebei Normal University, Hebei Normal University, Shijiazhuang 050024, P.R. China
| | - Zhijun Yu
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, P.R. China
| | - Jingze Liu
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, P.R. China
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Dabo M, Jaiswal SK, Dakora FD. Phylogenetic evidence of allopatric speciation of bradyrhizobia nodulating cowpea (Vigna unguiculata L. walp) in South African and Mozambican soils. FEMS Microbiol Ecol 2020; 95:5490326. [PMID: 31095296 PMCID: PMC6531793 DOI: 10.1093/femsec/fiz067] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 05/14/2019] [Indexed: 01/19/2023] Open
Abstract
The legume host and soil environment play a major role in establishing effective symbiosis with diverse rhizobia for plant growth promotion and nodule formation. The aim of this study was to assess the morpho-physiology, distribution and phylogenetic position of rhizobia nodulating cowpea from South Africa and Mozambique. The results showed that the isolates were highly diverse in their appearance on yeast mannitol agar plates. The isolates tested also showed an ability to produce IAA at concentrations ranging from 0.64 to 56.46 μg.ml−1 and to solubilise phosphorus at levels from 0 to 3.55 index. Canonical correspondence analysis showed that soil pH and mineral nutrients significantly influenced bradyrhizobial distribution. Analysis of BOX-PCR placed the isolates in eight major clusters with 0.01 to 1.00 similarity coefficient which resulted in 45 unique BOX-types. Phylogenetic analyses based on 16S rRNA, atpD, glnII, gyrB and recA gene sequences showed distinct novel evolutionary lineages within the genus Bradyrhizobium, with some of them being closely related to Bradyrhizobium kavangense, B. subterraneum and B. pachyrhizi. Furthermore, symbiotic gene phylogenies suggested that the isolates’ sym loci probably relates to the isolates’ geographical origin. The results indicated that geographical origin did affect the isolates’ phylogenetic placement and could be the basis for allopatric speciation
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Affiliation(s)
- Mamadou Dabo
- Department of Crop Sciences, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa
| | - Sanjay K Jaiswal
- Chemistry Department, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa
| | - Felix D Dakora
- Chemistry Department, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa
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Characterization of Bradyrhizobium strains indigenous to Western Australia and South Africa indicates remarkable genetic diversity and reveals putative new species. Syst Appl Microbiol 2020; 43:126053. [PMID: 31937424 DOI: 10.1016/j.syapm.2020.126053] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 12/30/2019] [Accepted: 01/01/2020] [Indexed: 01/01/2023]
Abstract
Bradyrhizobium are N2-fixing microsymbionts of legumes with relevant applications in agricultural sustainability, and we investigated the phylogenetic relationships of conserved and symbiotic genes of 21 bradyrhizobial strains. The study included strains from Western Australia (WA), isolated from nodules of Glycine spp. the country is one genetic center for the genus and from nodules of other indigenous legumes grown in WA, and strains isolated from forage Glycine sp. grown in South Africa. The 16S rRNA phylogeny divided the strains in two superclades, of B. japonicum and B. elkanii, but with low discrimination among the species. The multilocus sequence analysis (MLSA) with four protein-coding housekeeping genes (dnaK, glnII, gyrB and recA) pointed out seven groups as putative new species, two within the B. japonicum, and five within the B. elkanii superclades. The remaining eleven strains showed higher similarity with six species, B. lupini, B. liaoningense, B. yuanmingense, B. subterraneum, B. brasilense and B. retamae. Phylogenetic analysis of the nodC symbiotic gene clustered 13 strains in three different symbiovars (sv. vignae, sv. genistearum and sv. retamae), while seven others might compose new symbiovars. The genetic profiles of the strains evaluated by BOX-PCR revealed high intra- and interspecific diversity. The results point out the high level of diversity still to be explored within the Bradyrhizobium genus, and further studies might confirm new species and symbiovars.
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Ibny FYI, Jaiswal SK, Mohammed M, Dakora FD. Symbiotic effectiveness and ecologically adaptive traits of native rhizobial symbionts of Bambara groundnut (Vigna subterranea L. Verdc.) in Africa and their relationship with phylogeny. Sci Rep 2019; 9:12666. [PMID: 31477738 PMCID: PMC6718677 DOI: 10.1038/s41598-019-48944-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 08/13/2019] [Indexed: 11/09/2022] Open
Abstract
Bambara groundnut (Vigna subterranea L. Verdc.) is an indigenous, drought-tolerant, underutilized African food legume, with the ability to fix atmospheric N2 in symbiosis with soil bacteria called rhizobia. The aim of this study was to assess the morpho-physiological, symbiotic and phylogenetic characteristics of rhizobia nodulating Bambara groundnut in Ghana, Mali and South Africa. The morpho-physiologically diverse isolates tested were also found to exhibit differences in functional efficiency and phylogenetic positions. Based on Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR banding patterns, the isolates were grouped into eight major clusters. The concentrations of Ca, Na and K in soils had a significant (p ≤ 0.01) effect on the distribution of rhizobia. Though many isolates were symbiotically very effective, the effectiveness index varied markedly (p ≤ 0.05) among them. Moreover, the isolates also exhibited tolerance to a wide range of NaCl (0.5–7%), streptomycin (50–500 µg.ml−1), and kanamycin (25–150 µg.ml−1) concentrations. Additionally, these isolates could produce 0.02 to 69.71 µg.ml−1 of indole-3-acetic acid (IAA) in tryptophan-supplemented medium, as well as solubilize tri-calcium phosphate. Phylogenetic analysis of these rhizobial isolates using 16S rRNA, atpD, glnII, gyrB, recA and symbiotic (nifH and nodC) gene sequences revealed distinct and novel evolutionary lineages related to the genus Bradyrhizobium, with some of them being very close to Bradyrhizobium vignae, B. kavangense, B. subterraneum, B. elkanii and B. pachyrhizi.
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Affiliation(s)
- Fadimata Y I Ibny
- Department of Crop Sciences, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa
| | - Sanjay K Jaiswal
- Chemistry Department, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa.
| | - Mustapha Mohammed
- Department of Crop Sciences, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa
| | - Felix D Dakora
- Chemistry Department, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa.
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Ormeño-Orrillo E, Martínez-Romero E. A Genomotaxonomy View of the Bradyrhizobium Genus. Front Microbiol 2019; 10:1334. [PMID: 31263459 PMCID: PMC6585233 DOI: 10.3389/fmicb.2019.01334] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 05/28/2019] [Indexed: 11/13/2022] Open
Abstract
Whole genome analysis of the Bradyrhizobium genus using average nucleotide identity (ANI) and phylogenomics showed the genus to be essentially monophyletic with seven robust groups within this taxon that includes nitrogen-fixing nodule forming bacteria as well as free living strains. Despite the wide genetic diversity of these bacteria no indication was found to suggest that the Bradyrhizobium genus have to split in different taxa. Bradyrhizobia have larger genomes than other genera of the Bradyrhizobiaceae family, probably reflecting their metabolic diversity and different lifestyles. Few plasmids in the sequenced strains were revealed from rep gene analysis and a relatively low proportion of the genome is devoted to mobile genetic elements. Sequence diversity of recA and glnII gene metadata was used to theoretically estimate the number of existing species and to predict how many would exist. There may be many more species than those presently described with predictions of around 800 species in nature. Different arguments are presented suggesting that nodulation might have arose in the ancestral genus Bradyrhizobium.
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Affiliation(s)
- Ernesto Ormeño-Orrillo
- Laboratorio de Ecología Microbiana y Biotecnología, Departamento de Biología, Facultad de Ciencias, Universidad Nacional Agraria La Molina, Lima, Peru
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Avontuur JR, Palmer M, Beukes CW, Chan WY, Coetzee MPA, Blom J, Stępkowski T, Kyrpides NC, Woyke T, Shapiro N, Whitman WB, Venter SN, Steenkamp ET. Genome-informed Bradyrhizobium taxonomy: where to from here? Syst Appl Microbiol 2019; 42:427-439. [PMID: 31031014 DOI: 10.1016/j.syapm.2019.03.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 03/26/2019] [Accepted: 03/26/2019] [Indexed: 02/06/2023]
Abstract
Bradyrhizobium is thought to be the largest and most diverse rhizobial genus, but this is not reflected in the number of described species. Although it was one of the first rhizobial genera recognised, its taxonomy remains complex. Various contemporary studies are showing that genome sequence information may simplify taxonomic decisions. Therefore, the growing availability of genomes for Bradyrhizobium will likely aid in the delineation and characterization of new species. In this study, we addressed two aims: first, we reviewed the availability and quality of available genomic resources for Bradyrhizobium. This was achieved by comparing genome sequences in terms of sequencing technologies used and estimated level of completeness for inclusion in genome-based phylogenetic analyses. Secondly, we utilized these genomes to investigate the taxonomic standing of Bradyrhizobium in light of its diverse lifestyles. Although genome sequences differed in terms of their quality and completeness, our data indicate that the use of these genome sequences is adequate for taxonomic purposes. By using these resources, we inferred a fully resolved, well-supported phylogeny. It separated Bradyrhizobium into seven lineages, three of which corresponded to the so-called supergroups known for the genus. Wide distribution of key lifestyle traits such as nodulation, nitrogen fixation and photosynthesis revealed that these traits have complicated evolutionary histories. We present the first robust Bradyrhizobium species phylogeny based on genome sequence information for investigating the evolution of this important assemblage of bacteria. Furthermore, this study provides the basis for using genome sequence information as a resource to make important taxonomic decisions, particularly at the species and genus levels.
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Affiliation(s)
- Juanita R Avontuur
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa
| | - Marike Palmer
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa
| | - Chrizelle W Beukes
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa
| | - Wai Y Chan
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa; Biotechnology Platform, Agricultural Research Council Onderstepoort Veterinary Institute (ARC-OVI), Onderstepoort 0110, South Africa
| | - Martin P A Coetzee
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa
| | - Jochen Blom
- Bioinformatics and Systems Biology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Tomasz Stępkowski
- Autonomous Department of Microbial Biology, Faculty of Agriculture and Biology, Warsaw University of Life Sciences (SGGW), Poland
| | | | - Tanja Woyke
- DOE Joint Genome Institute, Walnut Creek, CA, United States
| | - Nicole Shapiro
- DOE Joint Genome Institute, Walnut Creek, CA, United States
| | - William B Whitman
- Department of Microbiology, University of Georgia, Athens, GA, United States
| | - Stephanus N Venter
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa
| | - Emma T Steenkamp
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa. http://emma.steenkamp.up.ac.za
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