Nitrogen-fixing Leguminous Symbioses. Nitrogen Fixation: Origins, Applications and Research Progress. Volume 7. Edited by M. J. Dilworth, E. K. James, J. I. Sprent and W. E. Newton. A. A. Dordrecht, The Netherlands: Springer Science. (2008), pp. 402, £115.50. ISBN 97-1-4020-3545-6.

2009 ◽  
Vol 45 (2) ◽  
pp. 239-240 ◽  
Author(s):  
Ron Wheatley
Keyword(s):  
Nitrogen Fixation ◽  
The Netherlands ◽  
Research Progress ◽  
Nitrogen Fixing

scholarly journals Research Progress and Perspectives of Nitrogen Fixing Bacterium,Gluconacetobacter diazotrophicus, in Monocot Plants

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
N. Eskin ◽  
K. Vessey ◽  
L. Tian
Keyword(s):  
Nitrogen Fixation ◽  
Research Progress ◽  
Research Development ◽  
Complex Root ◽  
Gluconacetobacter Diazotrophicus ◽  
Plant Origin ◽  
Nitrogen Fixing ◽  
Intercellular Spaces ◽  
The Past ◽  
Plant Crop

Gluconacetobacter diazotrophicusis a nitrogen fixing bacterium originally found in monocotyledon sugarcane plants in which the bacterium actively fixes atmosphere nitrogen and provides significant amounts of nitrogen to plants. This bacterium mainly colonizes intercellular spaces within the roots and stems of plants and does not require the formation of the complex root organ like nodule. The bacterium is less plant/crop specific and indeedG. diazotrophicushas been found in a number of unrelated plant species. Importantly, as the bacterium was of monocot plant origin, there exists a possibility that the nitrogen fixation feature of the bacterium may be used in many other monocot crops. This paper reviews and updates the research progress ofG. diazotrophicusfor the past 25 years but focuses on the recent research development.

scholarly journals Plasmids Related to the Symbiotic Nitrogen Fixation Are Not Only Cooperated Functionally but Also May Have Evolved over a Time Span in Family Rhizobiaceae

2020 ◽  
Vol 12 (11) ◽  
pp. 2002-2014
Author(s):  
Ling-Ling Yang ◽  
Zhao Jiang ◽  
Yan Li ◽  
En-Tao Wang ◽  
Xiao-Yang Zhi
Keyword(s):  
Nitrogen Fixation ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Symbiotic Nitrogen Fixation ◽  
Gene Families ◽  
Time Span ◽  
Soil Conditions ◽  
Gene Gain ◽  
Nitrogen Fixing ◽  
Pan Genome

Abstract Rhizobia are soil bacteria capable of forming symbiotic nitrogen-fixing nodules associated with leguminous plants. In fast-growing legume-nodulating rhizobia, such as the species in the family Rhizobiaceae, the symbiotic plasmid is the main genetic basis for nitrogen-fixing symbiosis, and is susceptible to horizontal gene transfer. To further understand the symbioses evolution in Rhizobiaceae, we analyzed the pan-genome of this family based on 92 genomes of type/reference strains and reconstructed its phylogeny using a phylogenomics approach. Intriguingly, although the genetic expansion that occurred in chromosomal regions was the main reason for the high proportion of low-frequency flexible gene families in the pan-genome, gene gain events associated with accessory plasmids introduced more genes into the genomes of nitrogen-fixing species. For symbiotic plasmids, although horizontal gene transfer frequently occurred, transfer may be impeded by, such as, the host’s physical isolation and soil conditions, even among phylogenetically close species. During coevolution with leguminous hosts, the plasmid system, including accessory and symbiotic plasmids, may have evolved over a time span, and provided rhizobial species with the ability to adapt to various environmental conditions and helped them achieve nitrogen fixation. These findings provide new insights into the phylogeny of Rhizobiaceae and advance our understanding of the evolution of symbiotic nitrogen fixation.

scholarly journals Genomic characterization and computational phenotyping of nitrogen-fixing bacteria isolated from Colombian sugarcane fields

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Luz K. Medina-Cordoba ◽  
Aroon T. Chande ◽  
Lavanya Rishishwar ◽  
Leonard W. Mayer ◽  
Lina C. Valderrama-Aguirre ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Nitrogen Fixation ◽  
Plant Growth ◽  
Phosphate Solubilization ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria ◽  
Promising Tool ◽  
A Genome ◽  
Plant Growth Promoting ◽  
Growth Promoting

AbstractPrevious studies have shown the sugarcane microbiome harbors diverse plant growth promoting microorganisms, including nitrogen-fixing bacteria (diazotrophs), which can serve as biofertilizers. The genomes of 22 diazotrophs from Colombian sugarcane fields were sequenced to investigate potential biofertilizers. A genome-enabled computational phenotyping approach was developed to prioritize sugarcane associated diazotrophs according to their potential as biofertilizers. This method selects isolates that have potential for nitrogen fixation and other plant growth promoting (PGP) phenotypes while showing low risk for virulence and antibiotic resistance. Intact nitrogenase (nif) genes and operons were found in 18 of the isolates. Isolates also encode phosphate solubilization and siderophore production operons, and other PGP genes. The majority of sugarcane isolates showed uniformly low predicted virulence and antibiotic resistance compared to clinical isolates. Six strains with the highest overall genotype scores were experimentally evaluated for nitrogen fixation, phosphate solubilization, and the production of siderophores, gibberellic acid, and indole acetic acid. Results from the biochemical assays were consistent and validated computational phenotype predictions. A genotypic and phenotypic threshold was observed that separated strains by their potential for PGP versus predicted pathogenicity. Our results indicate that computational phenotyping is a promising tool for the assessment of bacteria detected in agricultural ecosystems.

Nitrogen fixation

1976 ◽  
Vol 274 (934) ◽  
pp. 341-358 ◽  
Keyword(s):  
Nitrogen Fixation ◽  
Metabolic Regulation ◽  
Higher Plants ◽  
Focal Point ◽  
Nitrogenase Activity ◽  
Nitrogen Fixing ◽  
Blue Green Algae ◽  
International Biological Programme ◽  
The 1960S ◽  
Biological Programme

The International Biological Programme served as a focal point for studies on biological nitrogen fixation during the 1960s. The introduction of the acetylene reduction technique for measuring nitrogenase activity in the field led to estimates becoming available of the contribution of lichens, blue-green algae, nodulated non-legumes and bacterial-grass associations, as well as of legumes. Other studies carried out on the physiology and biochemistry of the process led to the eventual purification and characterization of the nitrogenase enzyme. These studies, collectively, provided the springboard for current work, so essential in view of the present energy crisis, on how to increase the use and efficiency of nitrogen-fixing plants, on the metabolic regulation of the nitrogenase enzyme and on the genetics of the nitrogen-fixing process, both in higher plants and in free-living micro-organisms.

scholarly journals Αναπρογραμματισμός του μεταβολισμού του Lotus japonicus σε μεταγραφικό, βιοχημικό και μεταβολομικό επίπεδο κατά τη συμβιωτική αζωτοδέσμευση

2016 ◽  
Author(s):  
Χρυσάνθη Καλλονιάτη
Keyword(s):  
Nitrogen Fixation ◽  
Metabolite Profiling ◽  
Symbiotic Nitrogen Fixation ◽  
Sulfur Metabolism ◽  
Lotus Japonicus ◽  
Nitrogen Fixing ◽  
Model Legume ◽  
Whole Plant ◽  
Plant Level ◽  
Molecular And Biochemical Mechanisms

Symbiotic nitrogen fixation in legumes takes place in specialized organs called nodules,which become the main source of assimilated nitrogen for the whole plant. Symbiotic nitro‐gen fixation requires exquisite integration of plant and bacterial metabolism and involvesglobal changes in gene expression and metabolite accumulation in both rhizobia and thehost plant. In order to study the metabolic changes mediated by symbiotic nitrogen fixationon a whole‐plant level, metabolite levels were profiled by gas chromatography–mass spec‐trometry in nodules and non‐symbiotic organs of Lotus japonicus plants uninoculated or in‐oculated with M. loti wt,  ΔnifA or  ΔnifH fix‐ strains. Furthermore, transcriptomic andbiochemical approaches were combined to study sulfur metabolism in nodules, its link tosymbiotic nitrogen fixation, and the effect of nodules on whole‐plant sulfur partitioning andmetabolism. It is well established that nitrogen and sulfur (S) metabolism are tightly en‐twined and sulfur is required for symbiotic nitrogen fixation, however, little is known aboutthe molecular and biochemical mechanisms governing sulfur uptake and assimilation duringsymbiotic nitrogen fixation. Transcript profiling in Lotus japonicus was combined with quan‐tification of S‐metabolite contents and APR activity in nodules and in non‐symbiotic organsof plants uninoculated or inoculated with M. loti wt, ΔnifA or ΔnifH fix‐ strains. Moreover,sulfate uptake and its distribution into different plant organs were analyzed and 35S‐flux intodifferent S‐pools was monitored. Metabolite profiling revealed that symbiotic nitrogen fixa‐tion results in dramatic changes of many aspects of primary and secondary metabolism innodules which leads to global reprogramming of metabolism of the model legume on awhole‐plant level. Moreover, our data revealed that nitrogen fixing nodules represent athiol‐rich organ. Their high APR activity and 35S‐flux into cysteine and its metabolites in com‐bination with the transcriptional up‐regulation of several genes involved in sulfur assimila‐tion highlight the function of nodules as a new site of sulfur assimilation. The higher thiolcontent observed in non‐symbiotic organs of nitrogen fixing plants in comparison touninoculated plants cannot be attributed to local biosynthesis, indicating that nodules couldserve as a novel source of reduced sulfur for the plant, which triggers whole‐plant repro‐gramming of sulfur metabolism. Interestingly, the changes in metabolite profiling and theenhanced thiol biosynthesis in nodules and their impact on the whole‐plant sulfur, carbonand nitrogen economy are dampened in fix‐ plants, which in most respects metabolically re‐sembled uninoculated plants, indicating a strong interaction between nitrogen fixation andsulfur and carbon metabolism.

scholarly journals Novel Reiterated Fnr-Type Proteins Control the Production of the Symbiotic Terminal Oxidase cbb3 in Rhizobium etli CFN42

2007 ◽  
Vol 20 (10) ◽  
pp. 1241-1249 ◽  
Author(s):  
Manuel J. Granados-Baeza ◽  
Nicolás Gómez-Hernández ◽  
Yolanda Mora ◽  
María J. Delgado ◽  
David Romero ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Oxygen Affinity ◽  
Structural Similarity ◽  
Transcriptional Regulators ◽  
Terminal Oxidase ◽  
Nitrogen Fixing ◽  
Rhizobium Etli ◽  
High Oxygen Affinity ◽  
Key Genes

Symbiotic nitrogen-fixing bacteria express a terminal oxidase with a high oxygen affinity, the cbb3-type oxidase encoded by the fixNOQP operon. Previously, we have shown that, in Rhizobium etli CFN42, the repeated fixNOQP operons (fixNOQPd and fixNOQPf) have a differential role in nitrogen fixation. Only the fixNOQPd operon is required for the establishment of an effective symbiosis; microaerobic induction of this operon is under the control of at least three transcriptional regulators, FixKf, FnrNd, and FnrNchr, belonging to the Crp/Fnr family. In this work, we describe two novel Crp/Fnr-type transcriptional regulators (StoRd and StoRf, symbiotic terminal oxidase regulators) that play differential roles in the control of key genes for nitrogen fixation. Mutations either in stoRd or stoRf enhance the microaerobic expression of both fixNOQP reiterations, increasing also the synthesis of the cbb3-type oxidase in nodules. Despite their structural similarity, a differential role of these genes was also revealed, since a mutation in stoRd but not in stoRf enhanced both the expression of fixKf and the nitrogen-fixing capacity of R. etli CFN42.

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