Nitrogenase activity in response to restricted shoot growth in Alnus incana

1983 ◽  
Vol 61 (11) ◽  
pp. 2949-2955 ◽  
Author(s):  
Kerstin Huss-Danell ◽  
Anita Sellstedt
Keyword(s):  
Root Biomass ◽  
Shoot Growth ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Alnus Incana ◽  
Nitrogen Fixing ◽  
Combined Nitrogen ◽  
Carbon Compounds ◽  
Source Sink ◽  
Nitrogen Percentage

In the Alnus–Frankia symbiosis the nitrogen-fixing root nodules are one of the sinks for carbon compounds newly formed in photosynthesis and exported from the leaves (source). The competition for assimilates between shoot tips and root nodules was studied by reducing shoot growth. Cloned plants of Alnus incana (L.) Moench were grown without combined nitrogen in a growth chamber. Shoot growth was inhibited by excision of all buds or by induced dormancy. The experiments showed an increased root biomass in the treated plants, indicating a changed source–sink balance. The treatments never caused an increased nitrogenase activity (C2H2-dependent C2H4 production); rather it was decreased. The nitrogenase activity was always correlated with leaf areas. It was also correlated with growth, which is shown by the similar nitrogen percentage in intact and treated plants.

Characterization of an ineffective actinorhizal microsymbiont, Frankia sp. EuI1 (Actinomycetales)

1980 ◽  
Vol 26 (9) ◽  
pp. 1072-1089 ◽  
Author(s):  
Dwight Baker ◽  
William Newcomb ◽  
John G. Torrey
Keyword(s):  
Host Range ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Host Cells ◽  
Vesicle Formation ◽  
Nitrogen Fixing ◽  
Elaeagnus Umbellata

The actinomycete, Frankia sp. EuI1, isolated from root nodules of Elaeagnus umbellata is an infective endophyte but which lacks the ability to form an effective nitrogen-fixing symbiosis with its host. This ineffective organism can be distinguished easily from other frankiae, in vitro, on the basis of size, morphology, and the elaboration of a diffusible pigment. Cross-inoculation studies indicated that the host range of this symbiont is narrow and probably restricted to the Elaeagnaceae. In all cases of nodulation the symbiosis never developed nitrogenase activity and the microsymbiont never produced endophytic vesicles within the infected host cells. Sporangia were produced in vivo and in vitro so the morphogenetic block is apparently restricted to vesicle formation.

Evolution of nitrogen-fixing symbioses

1985 ◽  
Vol 85 (3-4) ◽  
pp. 215-237 ◽  
Author(s):  
J. I. Sprent ◽  
J. A. Raven
Keyword(s):  
Root Nodules ◽  
Land Plants ◽  
Oxygenic Photosynthesis ◽  
Ecological Niches ◽  
Energy Costs ◽  
Nitrogen Fixing ◽  
Infection Structure ◽  
Combined Nitrogen ◽  
High Level ◽  
Biological Nitrogen

SynopsisBecause of both the energy costs and the slowness of the reactions of the nitrogenase complex compared with those involving some form of combined nitrogen (oxidised or reduced), we argue that the evolution of nitrogen-fixing organisms required an environment which was very limited in combined nitrogen. This is thought to have occurred after phototrophy evolved, but before water was used as a hydrogen donor (and therefore oxygen was present in the atmosphere). After oxygenic photosynthesis evolved, the need for a high level of biological nitrogen-fixation remained, since abiotic inputs were insufficient to keep pace with the rapidly evolving biomass (flora and fauna). Symbiotic fixation probably first evolved in the form of casual associations between cyanobacteria and most other groups of plants. By inhabiting the sporophytic generation of evolving land plants (cycads in particular), protection against nitrogenase-inactivating oxygen and a more desiccating environment was achieved simultaneously.We envisage nodulated plants arising by the transfer ofnifgenes into tumour-forming bacteria. In the case of legumes, these would be ancestors of extant agrobacteria, which gain entry into their hostsviawounds. Co-evolution of symbionts from nitrogen-fixing tumours has taken several routes, leading to extant nodules differing in mode of infection, structure and physiology. Evolution towards optimisation of oxygen usage is continuing.Nitrogen-fixing symbiosis in animal systems is only advantageous in specialised ecological niches in which wood is the sole dietary intake. In the case of shipworms, the symbiosis has many of the advanced features associated with nitrogen fixing root nodules.

Ammonium effects on function and structure of nitrogen-fixing root nodules of Alnus incana (L.) Moench

Planta ◽  
1982 ◽  
Vol 156 (4) ◽  
pp. 332-340 ◽  
Author(s):  
Kerstin Huss-Danell ◽  
Anita Sellstedt ◽  
Anita Flower-Ellis ◽  
Michael Sj�str�m
Keyword(s):  
Root Nodules ◽  
Alnus Incana ◽  
Nitrogen Fixing

scholarly journals Bacterial IAA-Delivery into Medicago Root Nodules Triggers a Balanced Stimulation of C and N Metabolism Leading to a Biomass Increase

2019 ◽  
Vol 7 (10) ◽  
pp. 403 ◽  
Author(s):  
Roberto Defez ◽  
Anna Andreozzi ◽  
Silvia Romano ◽  
Gabriella Pocsfalvi ◽  
Immacolata Fiume ◽  
...  
Keyword(s):  
Plant Growth ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Soluble Sugars ◽  
Plant Growth Promoting Rhizobacteria ◽  
Nitrogen Fixing ◽  
Genomic Changes ◽  
N Metabolism ◽  
C And N ◽  
Biomass Increase

Indole-3-acetic acid (IAA) is the main auxin acting as a phytohormone in many plant developmental processes. The ability to synthesize IAA is widely associated with plant growth-promoting rhizobacteria (PGPR). Several studies have been published on the potential application of PGPR to improve plant growth through the enhancement of their main metabolic processes. In this study, the IAA-overproducing Ensifer meliloti strain RD64 and its parental strain 1021 were used to inoculate Medicago sativa plants. After verifying that the endogenous biosynthesis of IAA did not lead to genomic changes during the initial phases of the symbiotic process, we analyzed whether the overproduction of bacterial IAA inside root nodules influenced, in a coordinated manner, the activity of the nitrogen-fixing apparatus and the photosynthetic function, which are the two processes playing a key role in legume plant growth and productivity. Higher nitrogen-fixing activity and a greater amount of total nitrogen (N), carbon (C), Rubisco, nitrogen-rich amino acids, soluble sugars, and organic acids were measured for RD64-nodulated plants compared to the plants nodulated by the wild-type strain 1021. Furthermore, the RD64-nodulated plants showed a biomass increase over time, with the highest increment (more than 60%) being reached at six weeks after infection. Our findings show that the RD64-nodulated plants need more substrate derived from photosynthesis to generate the ATP required for their increased nitrogenase activity. This high carbohydrate demand further stimulates the photosynthetic function with the production of molecules that can be used to promote plant growth. We thus speculate that the use of PGPR able to stimulate both C and N metabolism with a balanced C/N ratio represents an efficient strategy to obtain substantial gains in plant productivity.

scholarly journals FORMATION AND FUNCTIONING OF SYMBIOTIC SYSTEMS OF SOYA – BRADYRHIZOBIUM JAPONICUM FOR THE INFLUENCE OF COMPLEXES OF NANOPARTICLES OF CARBOXYLATES OF MICROELEMENTS

2019 ◽  
Vol 29 ◽  
pp. 12-20
Author(s):  
S. Ya. Kots ◽  
L. I. Rybachenko ◽  
P. P. Pukhtayevych ◽  
K. A. Mokrytsky
Keyword(s):  
Nitrogenase Activity ◽  
Root Nodules ◽  
Abiotic Factors ◽  
Nitrogen Fixing ◽  
Highly Active ◽  
Food And Feed ◽  
Environmentally Safe ◽  
Soybean Plants ◽  
Feed Protein ◽  
High Yields

Objective. To study the effect of combined preparations based on highly active strains of Brad-yrhizobium japonicum and complexes of carboxylates of trace elements germanium, molybdenum, and ferrum on a symbiotic apparatus of soybean plants, in order to increase the efficiency of bacte-rial inoculants. Methods. Gas chromatography, microbiological, physiological. Results. The com-bination of a microbiological preparation based on efficient strains of nodule bacteria with complexes of nanoparticles of carboxylates Mo, Fe, Ge was found to promote the enhancement of nodulation activity, provide growth of mass of root nodules, activate the nitrogen-fixing activity of symbiotic soybean systems. When use the preparation combined with germanium and molyb-denum compounds, nitrogenase activity increases by 23–63 %, in combination with inoculum with germanium and ferrum nanocarboxylates — by 14–21 % depending on the phases of soybean or-ganogenesis. The complex application of biological and abiotic factors influencing the formation and functioning of symbiotic nitrogen-fixing systems contributes to the improvement of plant mor-phometric parameters and provides high yields of this crop. At the same time, it was established that germanium carboxylate complexes with molybdenum carboxylate, as well as germanium nanocarboxylates, should be used as effective stimulants for the formation of seed productivity of soybean plants and nitrogen-fixing activity of symbiotic systems created with their participation. In the experiment, soybean yield under the combination of B. japonicum with germanium and molyb-denum nanocarboxylates increased by 10 %, and by 13 % — under the complex application of bac-terial inoculum with germanium and ferrum carboxylate nanoparticles. Conclusion. Application of these complexes of nanocomponents in microbiological production technologies will allow plants to be supplied with additional nutritional elements, forming effective plant-microbial systems and ob-taining high and stable crops of environmentally safe food and feed protein.

Adaptation of nitrogenase to varying oxygen tension and the role of the vesicle in root nodules of Alnus incana ssp. rugosa

1988 ◽  
Vol 66 (9) ◽  
pp. 1772-1779 ◽  
Author(s):  
Warwick B. Silvester ◽  
Janet K. Silvester ◽  
John G. Torrey
Keyword(s):  
Flow System ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Major Change ◽  
Dark Field ◽  
Alnus Incana ◽  
Major Barrier ◽  
Dark Field Microscopy ◽  
Nodule Morphology

Growth of Alnus incana ssp. rugosa plants with root systems at Po2 levels of 5, 21, and 40 kPa showed no significant differences among treatments over a 6-week period. Nitrogenase activity of attached nodulated foot systems run in an opencuvette continuous-flow system generally was responsive to Po2 over a broad range around the optimum. Plants expressed acetylene-induced and oxygen-induced transient declines in nitrogenase activity, from which they spontaneously recovered. Nitrogenase activity was seldom stable at any one Po2 during assay with apparent adaptation to both above- and below-ambient Po2 Nodule morphology showed quantitative decreases in aeration pathways as ambient Po2 was increased, with air spaces in the cortex and infected tissue being significantly affected. The major change in response to Po2 was the change in vesicle structure. Vesicles from nodules at low Po2 showed a vanishingly thin vesicle envelope under dark-field microscopy, while at high Po2 vesicles appeared very bright and apparently thickened. The results suggest that the major barrier to O2 diffusion in Alnus nodules is the vesicle envelope of the bacterium.

scholarly journals Paraburkholderia phymatum Homocitrate Synthase NifV Plays a Key Role for Nitrogenase Activity during Symbiosis with Papilionoids and in Free-Living Growth Conditions

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 952
Author(s):  
Paula Bellés-Sancho ◽  
Martina Lardi ◽  
Yilei Liu ◽  
Sebastian Hug ◽  
Marta Adriana Pinto-Carbó ◽  
...  
Keyword(s):  
Nitrogenase Activity ◽  
Root Nodules ◽  
Growth Conditions ◽  
Lysine Biosynthesis ◽  
Metabolome Analysis ◽  
Plant Host ◽  
Free Living ◽  
Bacterial Enzyme ◽  
Homocitrate Synthase ◽  
Iron Molybdenum Cofactor

Homocitrate is an essential component of the iron-molybdenum cofactor of nitrogenase, the bacterial enzyme that catalyzes the reduction of dinitrogen (N2) to ammonia. In nitrogen-fixing and nodulating alpha-rhizobia, homocitrate is usually provided to bacteroids in root nodules by their plant host. In contrast, non-nodulating free-living diazotrophs encode the homocitrate synthase (NifV) and reduce N2 in nitrogen-limiting free-living conditions. Paraburkholderia phymatum STM815 is a beta-rhizobial strain, which can enter symbiosis with a broad range of legumes, including papilionoids and mimosoids. In contrast to most alpha-rhizobia, which lack nifV, P. phymatum harbors a copy of nifV on its symbiotic plasmid. We show here that P. phymatum nifV is essential for nitrogenase activity both in root nodules of papilionoid plants and in free-living growth conditions. Notably, nifV was dispensable in nodules of Mimosa pudica despite the fact that the gene was highly expressed during symbiosis with all tested papilionoid and mimosoid plants. A metabolome analysis of papilionoid and mimosoid root nodules infected with the P. phymatum wild-type strain revealed that among the approximately 400 measured metabolites, homocitrate and other metabolites involved in lysine biosynthesis and degradation have accumulated in all plant nodules compared to uninfected roots, suggesting an important role of these metabolites during symbiosis.

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