Diversity of symbiotic rhizobia resident in Canadian soils

2003 ◽  
Vol 83 (Special Issue) ◽  
pp. 311-319 ◽  
Author(s):  
D. Prévost and E. S P. Bromfield
Keyword(s):  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum ◽  
Genetic Manipulation ◽  
Genotypic Variation ◽  
Natural Soil ◽  
Symbiotic Association ◽  
Canadian Soils ◽  
Plant Growth Promoting ◽  
Rhizobial Species ◽  
Biological Nitrogen

The dependency of agriculture on nitrogen fertilizer inputs is associated with adverse effects on the environment and human health. The importance of biological nitrogen fixation by rhizobia in symbiotic association with legumes is underscored by its potential to reduce or replace chemical fertilizer inputs. This paper reviews research on the diversity of the symbiotic rhizobia resident in Canadian soils. Research has focussed on phenotypic and genotypic variation (e.g., nitrogen fixing efficacy, nodulating competitiveness, host range, adaptation to cool climate) within rhizobial species with the objective of selecting efficient strains for use in inoculants for legume crops. The genetic diversity of rhizobia resident in Canadian soils has been reported only for Sinorhizobium meliloti, Rhizobium leguminosarum and Mesorhizobium spp. There is a need for further studies on populations of other rhizobial species, particularly those associated with native legumes. Exploiting the diversity present in natural soil populations via selection and genetic manipulation should permit the development of superior strains for use in legume inoculants. Other rhizobial traits that may be exploited include plant growth-promoting activity and ability to degrade pollutants. Key words: Symbiotic rhizobia, diversity, Canadian soils

scholarly journals Biosynthesis of UDP-xylose and UDP-arabinose in Sinorhizobium meliloti 1021: first characterization of a bacterial UDP-xylose synthase, and UDP-xylose 4-epimerase

Microbiology ◽  
2011 ◽  
Vol 157 (1) ◽  
pp. 260-269 ◽  
Author(s):  
Xiaogang Gu ◽  
Sung G. Lee ◽  
Maor Bar-Peled
Keyword(s):  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum ◽  
Glucuronic Acid ◽  
Functional Studies ◽  
H Nmr ◽  
New Information ◽  
Genes Encoding ◽  
Rhizobial Species ◽  
Insight Into

Sinorhizobium meliloti is a soil bacterium that fixes nitrogen after being established inside nodules that can form on the roots of several legumes, including Medicago truncatula. A mutation in an S. meliloti gene (lpsB) required for lipopolysaccharide synthesis has been reported to result in defective nodulation and an increase in the synthesis of a xylose-containing glycan. Glycans containing xylose as well as arabinose are also formed by other rhizobial species, but little is known about their structures and the biosynthetic pathways leading to their formation. To gain insight into the biosynthesis of these glycans and their biological roles, we report the identification of an operon in S. meliloti 1021 that contains two genes encoding activities not previously described in bacteria. One gene encodes a UDP-xylose synthase (Uxs) that converts UDP-glucuronic acid to UDP-xylose, and the second encodes a UDP-xylose 4-epimerase (Uxe) that interconverts UDP-xylose and UDP-arabinose. Similar genes were also identified in other rhizobial species, including Rhizobium leguminosarum, suggesting that they have important roles in the life cycle of this agronomically important class of bacteria. Functional studies established that recombinant SmUxs1 is likely to be active as a dimer and is inhibited by NADH and UDP-arabinose. SmUxe is inhibited by UDP-galactose, even though this nucleotide sugar is not a substrate for the 4-epimerase. Unambiguous evidence for the conversions of UDP-glucuronic acid to UDP-α-d-xylose and then to UDP-β-l-arabinose (UDP-arabinopyranose) was obtained using real-time 1H-NMR spectroscopy. Our results provide new information about the ability of rhizobia to form UDP-xylose and UDP-arabinose, which are then used for the synthesis of xylose- and arabinose-containing glycans.

scholarly journals Expression of an Exogenous 1-Aminocyclopropane-1-Carboxylate Deaminase Gene in Sinorhizobium meliloti Increases Its Ability To Nodulate Alfalfa

2004 ◽  
Vol 70 (10) ◽  
pp. 5891-5897 ◽  
Author(s):  
Wenbo Ma ◽  
Trevor C. Charles ◽  
Bernard R. Glick
Keyword(s):  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum ◽  
Higher Plants ◽  
Regulatory Gene ◽  
Regulatory Protein ◽  
Acc Deaminase ◽  
Plasmid Vector ◽  
Plant Growth Promoting Rhizobacteria ◽  
Infection Threads ◽  
Plant Growth Promoting

ABSTRACT 1-Aminocyclopropane-1-carboxylate (ACC) deaminase has been found in various plant growth-promoting rhizobacteria, including rhizobia. This enzyme degrades ACC, the immediate precursor of ethylene, and thus decreases the biosynthesis of ethylene in higher plants. The ACC deaminase of Rhizobium leguminosarum bv. viciae 128C53K was previously reported to be able to enhance nodulation of peas. The ACC deaminase structural gene (acdS) and its upstream regulatory gene, a leucine-responsive regulatory protein (LRP)-like gene (lrpL), from R. leguminosarum bv. viciae 128C53K were introduced into Sinorhizobium meliloti, which does not produce this enzyme, in two different ways: through a plasmid vector and by in situ transposon replacement. The resulting ACC deaminase-producing S. meliloti strains showed 35 to 40% greater efficiency in nodulating Medicago sativa (alfalfa), likely by reducing ethylene production in the host plants. Furthermore, the ACC deaminase-producing S. meliloti strain was more competitive in nodulation than the wild-type strain. We postulate that the increased competitiveness might be related to utilization of ACC as a nutrient within the infection threads.

BENEFITS OF NITROGENFIXATION TO THE NITROGENFIXING BACTERIA

2021 ◽  
pp. 42-43
Author(s):  
Shriya Phadnis
Keyword(s):  
Soil Bacteria ◽  
Agricultural Sector ◽  
Nitrogen Starvation ◽  
Review Article ◽  
Symbiotic Association ◽  
Symbiotic Relationship ◽  
Enzymatic Conversion ◽  
Mutualistic Symbiosis ◽  
Biological Nitrogen

The state of some plants being deprived from the availability of nitrogen causing nitrogen starvation leads to the phenomenon of Biological Nitrogen Fixation . Microorganisms are employed to enhance the availability of nitrogen to these plants. The major N2 - xing systems involve the symbiotic association between rhizobia soil bacteria and legumes. The enzymatic conversion of free nitrogen to ammonia occurs as a part of this symbiotic relationship. The signicant role of this phenomenon is enhancing the fertility of the soil and in the growth of the host plant that would otherwise be nitrogen limiting. This process has fascinated researchers in the agricultural sector for the yield of legume crops. This review article focuses on the benets that Rhizobium earns on being in mutualistic symbiosis with the leguminous plants.

scholarly journals Prevalence of the Rhizobium etli-Like Allele in Genes Coding for 16S rRNA among the Indigenous Rhizobial Populations Found Associated with Wild Beans from the Southern Andes in Argentina

1998 ◽  
Vol 64 (9) ◽  
pp. 3520-3524 ◽  
Author(s):  
O. Mario Aguilar ◽  
María Verónica López ◽  
Pablo M. Riccillo ◽  
Ramón A. González ◽  
Marcela Pagano ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rdna ◽  
Rhizobium Leguminosarum ◽  
Symbiotic Association ◽  
Rhizobium Etli ◽  
Center Of Origin ◽  
Wild Bean ◽  
Northwest Argentina ◽  
Bean Plants ◽  
Wild Beans

ABSTRACT A collection of rhizobial isolates from nodules of wild beans,Phaseolus vulgaris var. aborigineus, found growing in virgin lands in 17 geographically separate sites in northwest Argentina was characterized on the basis of host range, growth, hybridization to a nifH probe, analysis of genes coding for 16S rRNA (16S rDNA), DNA fingerprinting, and plasmid profiles. Nodules in field-collected wild bean plants were largely dominated by rhizobia carrying the 16S rDNA allele of Rhizobium etli. A similar prevalence of the R. etli allele was observed among rhizobia trapped from nearby soil. Intragroup diversity of wild bean isolates with either R. etli-like or Rhizobium leguminosarum bv. phaseoli-like alleles was generally found across northwest Argentina. The predominance of the R. etliallele suggests that in this center of origin of P. vulgaris the coevolution of Rhizobium spp. and primitive beans has resulted in this preferential symbiotic association.

scholarly journals The Effect of pH Stress on the Survival of Rhizobium Trifolii and Sinorhizobium Meliloti in Vitro

2013 ◽  
Vol 70 (2) ◽  
pp. 449-450
Author(s):  
Monica NISTE ◽  
Roxana VIDICAN ◽  
Ioan ROTAR ◽  
Rodica POP
Keyword(s):  
Sinorhizobium Meliloti ◽  
Agar Medium ◽  
Rhizobium Trifolii ◽  
Ph Values ◽  
Optimum Ph ◽  
Yeast Extract Mannitol ◽  
Rhizobial Species ◽  
The Impact ◽  
Different Soils

Nitrogen-fixing symbiotic bacteria known as rhizobia can exist in different soils and adapt to different environmental conditions. The aim of this study was to determine the impact of pH on the growth of Rhizobium trifolii and Sinorhizobium meliloti. Rhizobial species were isolated using yeast extract mannitol agar medium) in which the pH values were adjusted to 5.0, 6.0, 8.0 and 9.0 by adding HCl and NaOH. The optimum pH for rhizobia is neutral or slightly alkaline (pH 8) and they are more sensitive to acidity. Sinorhizobium meliloti developed better in an acid medium compared to Rhizobium trifolii.

scholarly journals Quorum quenching activity of the PGPR Bacillus subtilis UD1022 alters nodulation efficiency of Sinorhizobium meliloti on Medicago truncatula

2020 ◽  
Author(s):  
Amanda Rosier ◽  
Pascale B. Beauregard ◽  
Harsh P. Bais
Keyword(s):  
Bacillus Subtilis ◽  
Plant Growth ◽  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Quorum Quenching ◽  
Agricultural System ◽  
Synergistic Activity ◽  
Sustainable Solutions ◽  
Plant Growth Promoting ◽  
Growth Promoting

AbstractPlant growth promoting rhizobacteria (PGPR) have enormous potential for solving some of the myriad challenges facing our global agricultural system. Intense research efforts are rapidly moving the field forward and illuminating the wide diversity of bacteria and their plant beneficial activities. In the development of better crop solutions using these PGPR, producers are including multiple different species of PGPR in their formulations in a ‘consortia’ approach. While the intention is to emulate more natural rhizomicrobiome systems, the aspect of bacterial interactions has not been properly regarded. By using a tri-trophic model of Medicago truncatula A17 Jemalong, its nitrogen (N)-fixing symbiont Sinorhizobium meliloti Rm8530 and the PGPR Bacillus subtilis UD1022, we demonstrate indirect influences between the bacteria affecting their plant growth promoting activities. Co-cultures of UD1022 with Rm8530 significantly reduced Rm8530 biofilm formation and downregulated quorum sensing (QS) genes responsible for symbiotically active biofilm production. This work also identifies the presence and activity of a quorum quenching lactonase in UD1022 and proposes this as the mechanism for non-synergistic activity of this model ‘consortium’. These interspecies interactions may be common in the rhizosphere and are critical to understand as we seek to develop new sustainable solutions in agriculture.

A rhizobial homolog of IHF stimulates transcription of dctA in Rhizobium leguminosarum but not in Sinorhizobium meliloti

Gene ◽  
1999 ◽  
Vol 238 (2) ◽  
pp. 489-500 ◽  
Author(s):  
John Sojda ◽  
Baohua Gu ◽  
Joon Lee ◽  
Timothy R Hoover ◽  
B.Tracy Nixon
Keyword(s):  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum

scholarly journals The Medicago truncatula N5 Gene Encoding a Root-Specific Lipid Transfer Protein Is Required for the Symbiotic Interaction with Sinorhizobium meliloti

2009 ◽  
Vol 22 (12) ◽  
pp. 1577-1587 ◽  
Author(s):  
Youry Pii ◽  
Alessandra Astegno ◽  
Elisa Peroni ◽  
Massimo Zaccardelli ◽  
Tiziana Pandolfini ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Lipid Transfer Protein ◽  
Symbiotic Association ◽  
Lipid Transfer ◽  
Symbiotic Interaction ◽  
Transgenic Roots ◽  
Transfer Protein ◽  
Small Proteins

The Medicago truncatula N5 gene is induced in roots after Sinorhizobium meliloti infection and it codes for a putative lipid transfer protein (LTP), a family of plant small proteins capable of binding and transferring lipids between membranes in vitro. Various biological roles for plant LTP in vivo have been proposed, including defense against pathogens and modulation of plant development. The aim of this study was to shed light on the role of MtN5 in the symbiotic interaction between M. truncatula and S. meliloti. MtN5 cDNA was cloned and the mature MtN5 protein expressed in Escherichia coli. The lipid binding capacity and antimicrobial activity of the recombinant MtN5 protein were tested in vitro. MtN5 showed the capacity to bind lysophospholipids and to inhibit M. truncatula pathogens and symbiont growth in vitro. Furthermore, MtN5 was upregulated in roots after infection with either the fungal pathogen Fusarium semitectum or the symbiont S. meliloti. Upon S. meliloti infection, MtN5 was induced starting from 1 day after inoculation (dpi). It reached the highest concentration at 3 dpi and it was localized in the mature nodules. MtN5-silenced roots were impaired in nodulation, showing a 50% of reduction in the number of nodules compared with control roots. On the other hand, transgenic roots overexpressing MtN5 developed threefold more nodules with respect to control roots. Here, we demonstrate that MtN5 possesses biochemical features typical of LTP and that it is required for the successful symbiotic association between M. truncatula and S. meliloti.

scholarly journals Inoculation with Different Nitrogen-Fixing Bacteria and Arbuscular Mycorrhiza Affects Grain Protein Content and Nodule Bacterial Communities of a Fava Bean Crop

Agronomy ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 768
Author(s):  
Virginia Sánchez-Navarro ◽  
Raúl Zornoza ◽  
Ángel Faz ◽  
Catalina Egea-Gilabert ◽  
Margarita Ros ◽  
...  
Keyword(s):  
Protein Content ◽  
Crop Yield ◽  
Rhizobium Leguminosarum ◽  
Grain Protein Content ◽  
Grain Protein ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria ◽  
Yield And Quality ◽  
Biological Nitrogen ◽  
Bean Crop

The introduction of nitrogen fixing bacteria (NFB) and arbuscular mycorrhizal fungi (AMF) into the soil is an advisable agricultural practice for the crop, since it enhances nutrient and water uptake and tolerance to biotic and abiotic stresses. The aim of this work was to study plant nutrition, biological nitrogen fixation (BNF) and crop yield and quality, after inoculating seeds with NFBs ((Rhizobium leguminosarum, Burkholderia cenocepacia, Burkholderia vietnamiensis)) and/or AMFs (Rhizophagus irregularis, Claroideoglomus etunicatum, Claroideoglomus claroideum and Funneliformis mosseae) in a fava bean crop in two seasons. The composition of the nodule bacterial community was evaluated by the high-throughput sequencing analysis of bacterial 16 S rRNA genes. It was found that microbial inoculation accompanied by a 20% decrease in mineral fertilization had no significant effect on crop yield or the nutritional characteristics compared with a non-inoculated crop, except for an increase in the grain protein content in inoculated plants. None of the inoculation treatments increased biological nitrogen fixation over a non-inoculated level. The bacterial rRNA analysis demonstrated that the genus Rhizobium predominated in all nodules, both in inoculated and non-inoculated treatments, suggesting the previous presence of these bacteria in the soil. In our study, inoculation with Rhizobium leguminosarum was the most effective treatment for increasing protein content in seeds, while Burkholderia sp. was not able to colonise the plant nodules. Inoculation techniques used in fava beans can be considered an environmentally friendly alternative, reducing the input of fertilizers, while maintaining crop yield and quality, with the additional benefit of increasing the grain protein content. However, further research is required on the selection and detection of efficient rhizobial strains under local field conditions, above all those related to pH and soil type, in order to achieve superior nitrogen-fixing bacteria.

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