Détermination de l'identité isotopique de l'azote fixé par le Frankia associé au genre Alnus

1988 ◽  
Vol 66 (7) ◽  
pp. 1241-1247 ◽  
Author(s):  
A. M. Domenach ◽  
F. Kurdali ◽  
C. Danière ◽  
R. Bardin
Keyword(s):  
Nitrogen Fixation ◽  
Symbiotic Nitrogen Fixation ◽  
Alnus Glutinosa ◽  
Natural Ecosystem ◽  
Free Medium ◽  
Fixed Nitrogen ◽  
Aerial Parts ◽  
Reference Plant ◽  
N Enrichment ◽  
N Natural Abundance

To use the 15N natural abundance method to evaluate the symbiotic nitrogen fixation by actinorhizal trees, it is necessary to determine the isotopic identity of assimilated nitrogen from two sources: the soil and the air. This study reports an isotopic value of fixed nitrogen by two alder species (Alnus incana (L.) Moench and Alnus glutinosa (L.) Gaertn. growing on nitrogen-free medium in greenhouse experiments. The δ15N value of the aerial parts was −2. This value was stable with time and did not depend on the Frankia strains used. This value could be used to estimate the nitrogen fixation in the natural ecosystem. Other parameters such as the mobilization of nitrogen reserves and the choice of the reference plant must be investigated to apply this method. The nodules of these two alder species were enriched in 15N relative to the rest of the plant but there was no relationship between symbiotic effectiveness of Frankia strains and 15N enrichment of nodules. On the other hand, for naturally growing trees, an enrichment in 15N was found primarily in the vesicles of nodules that are the sites of nitrogen fixation.

Symbiosomes: temporary moonlighting organelles

2014 ◽  
Vol 460 (1) ◽  
pp. 1-11 ◽  
Author(s):  
David W. Emerich ◽  
Hari B. Krishnan
Keyword(s):  
Nitrogen Fixation ◽  
Symbiotic Nitrogen Fixation ◽  
Infected Plant ◽  
Plant Cells ◽  
Fixed Nitrogen ◽  
Moonlighting Proteins ◽  
Biological Nitrogen ◽  
Structural Entity ◽  
Leguminous Host

Symbiosomes are a unique structural entity that performs the role of biological nitrogen fixation, an energy-demanding process that is the primary entryway of fixed nitrogen into the biosphere. Symbiosomes result from the infection of specific rhizobial strains into the roots of an appropriate leguminous host plant forming an organ referred to as a nodule. Within the infected plant cells of the nodule, the rhizobia are encased within membrane-bounded structures that develop into symbiosomes. Mature symbiosomes create an environment that allows the rhizobia to differentiate into a nitrogen-fixing form called bacteroids. The bacteroids are surrounded by the symbiosome space, which is populated by proteins from both eukaryotic and prokaryotic symbionts, suggesting this space is the quintessential component of symbiosis: an inter-kingdom environment with the single purpose of symbiotic nitrogen fixation. Proteins associated with the symbiosome membrane are largely plant-derived proteins and are non-metabolic in nature. The proteins of the symbiosome space are mostly derived from the bacteroid with annotated functions of carbon metabolism, whereas relatively few are involved in nitrogen metabolism. An appreciable portion of both the eukaryotic and prokaryotic proteins in the symbiosome are also ‘moonlighting’ proteins, which are defined as proteins that perform roles unrelated to their annotated activities when found in an unexpected physiological environment. The essential functions of symbiotic nitrogen fixation of the symbiosome are performed by co-operative interactions of proteins from both symbionts some of which may be performing unexpected roles.

Symbiotic nitrogen fixation in a tropical rainforest: 15 N natural abundance measurements supported by experimental isotopic enrichment

2006 ◽  
Vol 173 (1) ◽  
pp. 154-167 ◽  
Author(s):  
Thijs L. Pons ◽  
Kristel Perreijn ◽  
Chris Van Kessel ◽  
Marinus J. A. Werger
Keyword(s):  
Nitrogen Fixation ◽  
Tropical Rainforest ◽  
Symbiotic Nitrogen Fixation ◽  
Natural Abundance ◽  
Isotopic Enrichment ◽  
N Natural Abundance

scholarly journals Nodulation and Nitrogen Fixation of Pongamia pinnata

2017 ◽  
Vol 4 (1) ◽  
pp. 1-12
Author(s):  
Phoebe N. Calica
Keyword(s):  
Nitrogen Fixation ◽  
Symbiotic Nitrogen Fixation ◽  
Current Knowledge ◽  
Fixed Nitrogen ◽  
Qualitative And Quantitative ◽  
Naturally Occurring ◽  
Reduction Assay ◽  
Quantitative Results ◽  
Preliminary Study ◽  
Growth And Reproduction

Nitrogen is one of the most important nutrients required by plants as a major component of all nucleic acids and proteins such as enzymes which control and enable their growth and reproduction. While much research has been conducted on the legume tree Pongamia (a candidate source for renewable biofuel), there is only a handful of studies on the mechanisms and regulation of nitrogen fixation, which is considered as one of the most important domestication traits that needs to be investigated.  Steps to optimize the symbiotic nitrogen fixation of Pongamia is, firstly, to select the best rhizobial isolates as inoculum among the naturally-occurring pool of bacteria in soils across Queensland. There have been reports on rhizobia nodulating Pongamia isolated from Western Australia and India but not in Queensland, Australia. This study is the first to report such rhizobia isolates that nodulated Pongamia.  Secondly, is to establish efficient nodulation by studying the factors such as nitrate and salinity. The published literature has provided extensive details on the effects of these factors in nodulation and their mechanisms in various legumes. However, only one preliminary study was published from our laboratory; the present study is the in-depth continuation of that effort. Lastly, nitrogen fixation in Pongamia must be assessed to determine if fixed nitrogen is sufficient to support its growth and reproduction. Acetylene reduction assay is the simplest and most common method of assessing fixed nitrogen but in this research, different methods were explored in order to compare both qualitative and quantitative results. This review summarises the current knowledge related to Pongamia, rhizobia, nodulation and nitrogen fixation.

scholarly journals Testing Whether Pre-Pod-Fill Symbiotic Nitrogen Fixation in Soybean Is Subject to Drift or Selection Over 100 Years of Soybean Breeding

2021 ◽  
Vol 3 ◽  
Author(s):  
Malinda S. Thilakarathna ◽  
Davoud Torkamaneh ◽  
Robert W. Bruce ◽  
Istvan Rajcan ◽  
Godfrey Chu ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Symbiotic Nitrogen Fixation ◽  
Root Nodules ◽  
Field Trials ◽  
Direct Selection ◽  
Oilseed Crop ◽  
Fixed Nitrogen ◽  
Soybean Breeding ◽  
Soybean Cultivars ◽  
The Impact

Soybean [Glycine max (L.) Merr.] is the world's leading legume crop and the largest oilseed crop. It forms a symbiotic relationship with rhizobia bacteria residing in root nodules that provide fixed nitrogen to host plants through symbiotic nitrogen fixation (SNF). In soybean, it has been widely reported that the highest SNF occurs at the pod-filling stage, associated with the peak demand for nitrogen. However, the majority of seed nitrogen is derived from remobilizing root/shoot nitrogen, representing cumulative SNF from the seedling stage to the pre-pod-fill stage. Therefore, the question arises as to whether there has also been selection for improved SNF at these earlier stages, or whether pre-pod-fill SNF traits have drifted. To test this hypothesis, in this study, pre-pod SNF-related traits were evaluated in soybean cultivars that span 100 years of breeding selection in the Canadian Province of Ontario. Specifically, we evaluated SNF traits in 19 pedigree-related historical cultivars and 25 modern cultivars derived from the University of Guelph soybean breeding program. Field trials were conducted at Woodstock, Ontario, Canada in 2016 and 2017, and various SNF-related traits were measured at pre-pod-fill stages (R1-R3), including nitrogen fixation capacity. Considerable variation was observed among Canadian soybean cultivars released over the past 100 years for pre-pod-fill nitrogen fixation. The modern soybean cultivars had similar or moderately higher pre-pod-fill SNF compared to the historical lines in terms of the percentage of nitrogen derived from the atmosphere (%Ndfa) and total shoot fixed nitrogen. These findings suggest that, despite no direct selection by breeders, pre-pod-fill nitrogen fixation, and associated SNF traits have been maintained and possibly improved in modern soybean breeding. However, the low level of pre-pod-fill SNF in some modern cultivars, and generally wide variation observed in SNF between them, suggest some level of genetic drift for this trait in some pedigrees. Specific historical and modern soybean cultivars were identified as potential parents to enable targeted breeding for improved pre-pod-fill SNF. This retrospective study sheds light on our understanding of the impact of decades of recent selective breeding on pre-pod-fill nitrogen fixation traits in soybean in a temperate environment.

scholarly journals Oxidative Stress Produced by Paraquat Reduces Nitrogen Fixation in Soybean-Bradyrhizobium diazoefficiens Symbiosis by Decreasing Nodule Functionality

Nitrogen ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 30-40
Author(s):  
Germán Tortosa ◽  
Sergio Parejo ◽  
Juan J. Cabrera ◽  
Eulogio J. Bedmar ◽  
Socorro Mesa
Keyword(s):  
Oxidative Stress ◽  
Nitrogen Fixation ◽  
Symbiotic Nitrogen Fixation ◽  
Dry Weight ◽  
Fixed Nitrogen ◽  
Biotic And Abiotic Stresses ◽  
Free Living ◽  
Soybean Plants ◽  
Soil Metal ◽  
Free Living Conditions

Soybean (Glycine max.) is one of the most important legumes cultivated worldwide. Its productivity can be altered by some biotic and abiotic stresses like global warming, soil metal pollution or over-application of herbicides like paraquat (1,1’-dimethyl-4,4’-bipyridinium dichloride). In this study, the effect of oxidative stress produced by paraquat addition (0, 20, 50 and 100 µM) during plant growth on symbiotic nitrogen fixation (SNF) and functionality of Bradyrhizobium diazoefficiens-elicited soybean nodules were evaluated. Results showed that the 50 µM was the threshold that B. diazoefficiens can tolerate under free-living conditions. In symbiosis with soybean, the paraquat addition statistically reduced the shoot and root dry weight of soybean plants, and number and development of the nodules. SNF was negatively affected by paraquat, which reduced total nitrogen content and fixed nitrogen close to 50% when 100 µM was added. These effects were due to the impairment of nodule functionality and the increased oxidative status of the nodules, as revealed by the lower leghaemoglobin content and the higher lipid peroxidation in soybean nodules from paraquat-treated plants.

Frankiasymbiosis as a source of nitrogen in forestry: a case study of symbiotic nitrogen-fixation in a mixed Alnus-Picea plantation in Scotland

1985 ◽  
Vol 85 (3-4) ◽  
pp. 263-282 ◽  
Author(s):  
D. C. Malcolm ◽  
J. E. Hooker ◽  
C. T. Wheeler
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Availability ◽  
Symbiotic Nitrogen Fixation ◽  
Clay Soil ◽  
Alnus Glutinosa ◽  
Preliminary Evidence ◽  
Rooting Depth ◽  
Alnus Rubra ◽  
Mixed Stands ◽  
Different Strains

SynopsisAlnus rubragrowing in the field in Scotland is nodulated effectively by local strains ofFrankia. Strains which have been isolated fromAlnus rubraat Lennox Forest show different growth medium requirements and colony morphology compared with isolates fromAlnus glutinosaand several different strains have been isolated from the same locality. Preliminary evidence suggests that some spore negative, northwest AmericanFrankiastrains may be more effective than local spore positive crushed nodule inoculum for nitrogen-fixation inAlnus rubra.On the moderately fertile clay soil of Lennox Forest, a mixed plantation of alternatePicea silchensisandAlnus rubrashowed no improvement in growth of spruce compared with pure spruce plots. However, the presence of alder increased upper soil nitrogen status by 585 kg ha ' which approximates the standard 150 kg N ha 'of fertiliser nitrogen applied in practice to nitrogen deficient stands at about 5-year intervals. Although the alder had penetrated the subsoil, there was no apparent effect on spruce rooting depth in the mixed stands in this high clay soil. In addition to nitrogen content, the total phosphorus of the upper soil horizons was improved in the mixed plots by an estimated 3–6 kg ha-1y1and it is suggested that this phosphorus may be brought from the subsoil by the deeper rooting alder and deposited on the surface in its litter.Although improved growth of spruce in mixture withAlnus rubrais only likely where pure spruce stands are stressed for nutrients, the potential benefits of symbiotic nitrogen-fixation in silvicultural practice make it desirable to investigate other species and provenances ofAlnussuited to British conditions, to achieve maximum symbiotic fixation of nitrogen by selection and inoculation with superior strains ofFrankiaand to include such plants in trials of mixtures on sites where nitrogen-availability may be critical.

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