scholarly journals Root Nodules on Podocarpus Lawrencei and Their Ecological Significance

1964 ◽  
Vol 17 (1) ◽  
pp. 44 ◽  
Author(s):  
FJ Bergersen ◽  
AB Costin
Keyword(s):  
Nitrogen Fixation ◽  
Slow Growth ◽  
Root Nodules ◽  
General Structure ◽  
Intracellular Bacteria ◽  
Atmospheric Nitrogen ◽  
Ecological Significance ◽  
Anatomical Studies ◽  
Isotopic Method ◽  
Mode Of Development

Nodulated roots from P. lawrencei growing on a scree on Mt. Ginini, near Canberra, have been shown by the isotopic method to fix atmospheric nitrogen. The importance of this in a plant which is a pioneer of exposed, rocky situations is discussed. Although significant, the amount of nitrogen fixed by the detached nodulated roots wa�s low: this may have been due to the small proportion of nodules with active tissue, but it is also consistent with the slow growth observed for this species. The nodulated roots also evolved hydrogen u.s observed during nitrogen fixation by legume nodules. Anatomical studies of the Podocarpu8 nodules confirmed early accounts of their general structure and mode of development but the symbiont was clearly a non-septate filamentous organism: no intracellular bacteria were observed.

The inorganic biochemistry of molybdoenzymes

1988 ◽  
Vol 21 (3) ◽  
pp. 299-329 ◽  
Author(s):  
Robert C. Bray
Keyword(s):  
Nitrogen Fixation ◽  
Trace Element ◽  
Xanthine Oxidase ◽  
Biological Nitrogen Fixation ◽  
Root Nodules ◽  
Atmospheric Nitrogen ◽  
Mammalian Enzyme ◽  
The 1950S ◽  
Biological Nitrogen

Molybednum-containing enzymes (Coughlan, 1980; Spiro, 1985) occupy a significant place in the development of the field now termed inorganic biochemistry. The importance of the metal as a biological trace element depends on its involvement in the known, and perhaps other as yet unknown, molybdoenzymes. That it plays a role in biological nitrogen fixation, the process whereby the enzyme nitrogenase in the root nodules of plants converts atmospheric nitrogen into ammonia, was recognized in the 1930s. The metal is also a constituent of a variety of other enzymes, having first been found in a mammalian enzyme, xanthine oxidase, in the 1950s.

scholarly journals Mutation in the ntrR Gene, a Member of the vap Gene Family, Increases the Symbiotic Efficiency of Sinorhizobium meliloti

2001 ◽  
Vol 14 (7) ◽  
pp. 887-894 ◽  
Author(s):  
Boglárka Oláh ◽  
Erno Kiss ◽  
Zoltán Györgypál ◽  
Judit Borzi ◽  
Gyöngyi Cinege ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Pathogenic Bacteria ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Nifh Gene ◽  
Dry Weight ◽  
Nodule Occupancy ◽  
Gene Encoding ◽  
Symbiotic Efficiency ◽  
Host Interactions

In specific plant organs, namely the root nodules of alfalfa, fixed nitrogen (ammonia) produced by the symbiotic partner Sinorhizobium meliloti supports the growth of the host plant in nitrogen-depleted environment. Here, we report that a derivative of S. meliloti carrying a mutation in the chromosomal ntrR gene induced nodules with enhanced nitrogen fixation capacity, resulting in an increased dry weight and nitrogen content of alfalfa. The efficient nitrogen fixation is a result of the higher expression level of the nifH gene, encoding one of the subunits of the nitrogenase enzyme, and nifA, the transcriptional regulator of the nif operon. The ntrR gene, controlled negatively by its own product and positively by the symbiotic regulator syrM, is expressed in the same zone of nodules as the nif genes. As a result of the nitrogen-tolerant phenotype of the strain, the beneficial effect of the mutation on efficiency is not abolished in the presence of the exogenous nitrogen source. The ntrR mutant is highly competitive in nodule occupancy compared with the wild-type strain. Sequence analysis of the mutant region revealed a new cluster of genes, termed the “ntrPR operon,” which is highly homologous to a group of vap-related genes of various pathogenic bacteria that are presumably implicated in bacterium-host interactions. On the basis of its favorable properties, the strain is a good candidate for future agricultural utilization.

scholarly journals NITROGEN FIXATION BY EXCISED SOY BEAN ROOT NODULES

1954 ◽  
Vol 208 (1) ◽  
pp. 29-39
Author(s):  
M.H. Aprison ◽  
Wayne E. Magee ◽  
R.H. Burris
Keyword(s):  
Nitrogen Fixation ◽  
Root Nodules ◽  
Bean Root

Systemic control of nodule formation by the plant N demand requires autoregulation dependent and independent mechanisms

2021 ◽  
Author(s):  
Marjorie Pervent ◽  
Ilana Lambert ◽  
Marc Tauzin ◽  
Alicia Karouani ◽  
Martha Nigg ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Nodule Formation ◽  
Atmospheric Nitrogen ◽  
Plant Nitrogen ◽  
Systemic Signaling ◽  
Systemic Control ◽  
Whole Plant ◽  
Strong Control ◽  
Mutant Genes ◽  
N Demand

Abstract In legumes interacting with rhizobia the formation of symbiotic organs involved in the acquisition of atmospheric nitrogen is depending of the plant nitrogen (N) demand. We used Medicago truncatula plants cultivated in split-root systems to discriminate between responses to local and systemic N signalings. We evidenced a strong control of nodule formation by systemic N-signaling but obtained no clear evidence of a local control by mineral nitrogen. Systemic signaling of the plant N demand controls numerous transcripts involved in the root transcriptome reprogramming associated to early rhizobia interaction and nodule formation. SUNN has an important role in this control but major systemic N signaling responses remained active in the sunn mutant. Genes involved in the activation of nitrogen fixation are regulated by systemic N signaling in the mutant, explaining why the hypernodulation phenotype is not associated to a higher nitrogen fixation of the whole plant. The control of the transcriptome reprogramming of nodule formation by systemic N signaling requires other pathway(s) that parallel the SUNN/CLE pathway.

On the Fixation of Atmospheric Nitrogen by Phoma Radicis Callunae, including a New Method for Investigating Nitrogenfixation in Micro-Organisms

1928 ◽  
Vol 6 (2) ◽  
pp. 167-189
Author(s):  
W. NEILSON JONES ◽  
M. LLEWELLYN SMITH
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Starvation ◽  
Molecular Nitrogen ◽  
Mycorrhizal Fungus ◽  
Growth Period ◽  
Calluna Vulgaris ◽  
Atmospheric Nitrogen ◽  
Free Medium ◽  
New Apparatus ◽  
Micro Organisms

(1) Evidence from chemical analyses of seeds of Calluna mdgaris and of seedlings grown on a nitrogen-free medium confirms the view that this plant can obtain nitrogenous supplies from the air, probably in the form of molecular nitrogen, in sufficient amount to prevent the advent of any symptoms of nitrogen starvation. (2) A new apparatus for the investigation of nitrogen-fixation by micro-organisms is described. (3) Using the above apparatus, experiments on the mycorrhizal fungus of Calluna vulgaris are described in which this organism was grown in pure culture on a nitrogen-free medium with and without a supply of molecular nitrogen. The evidence obtained indicates that the amount of glucose used by the fungus during growth, and the amount of nitrogen contained in the culture at the end of the growth period are greater under the former condition. It is concluded that the fungus in question can utilise the molecular nitrogen of the air in some degree under the conditions of the experiments, although these were not the most favourable possible for nitrogen-fixation. It is considered that the results obtained justify an extension of these experiments using a strain of the fungus freshly extracted from the Calluna plant.

scholarly journals Multimodal Spectroscopic Imaging of Pea Root Nodules to Assess the Nitrogen Fixation in the Presence of Biofertilizer Based on Nod-Factors

2021 ◽  
Vol 22 (23) ◽  
pp. 12991
Author(s):  
Katarzyna Susniak ◽  
Mikolaj Krysa ◽  
Dominika Kidaj ◽  
Monika Szymanska-Chargot ◽  
Iwona Komaniecka ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Mass Spectrometry Imaging ◽  
Root Nodules ◽  
Spectroscopic Imaging ◽  
Ionization Mass ◽  
Nod Factors ◽  
Pea Root ◽  
Ft Ir ◽  
Ir And Raman ◽  
Apparent Distribution

Multimodal spectroscopic imaging methods such as Matrix Assisted Laser Desorption/Ionization Mass Spectrometry Imaging (MALDI MSI), Fourier Transform Infrared spectroscopy (FT-IR) and Raman spectroscopy were used to monitor the changes in distribution and to determine semi quantitatively selected metabolites involved in nitrogen fixation in pea root nodules. These approaches were used to evaluate the effectiveness of nitrogen fixation by pea plants treated with biofertilizer preparations containing Nod factors. To assess the effectiveness of biofertilizer, the fresh and dry masses of plants were determined. The biofertilizer was shown to be effective in enhancing the growth of the pea plants. In case of metabolic changes, the biofertilizer caused a change in the apparent distribution of the leghaemoglobin from the edges of the nodule to its centre (the active zone of nodule). Moreover, the enhanced nitrogen fixation and presumably the accelerated maturation form of the nodules were observed with the use of a biofertilizer.

Morphological and biochemical changes in peanut nodules during photosynthate stress

1992 ◽  
Vol 38 (6) ◽  
pp. 526-533 ◽  
Author(s):  
A. B. M. Siddique ◽  
A. K. Bal
Keyword(s):  
Nitrogen Fixation ◽  
Root Nodules ◽  
Ultrastructural Level ◽  
Malate Synthase ◽  
Morphological Evidence ◽  
Lipid Bodies ◽  
Biochemical Status ◽  
Short Period ◽  
Infected Cells ◽  
Ultrastructural Damage

Nitrogen fixation in legume root nodules is believed to be supported by the supply of photosynthate of the current photoperiod. However, in peanut nodules, prolonged periods of darkness or detopping do not disrupt nitrogen fixation for at least 48 h. During this period, nodule oleosomes (lipid bodies) have been shown to decrease in number within the infected cells, and it has been suggested that lipids from oleosomes are mobilized to maintain the energy and carbon requirements of the nitrogen-fixing nodules. We present morphological evidence, at the ultrastructural level, for the utilization of oleosomes during photosynthate stress. The biochemical status of the nodule has also been assessed and correlated with ultrastructure. For comparison cowpea nodules were used that totally lacked oleosomes. In peanut nodules leghemoglobin and total protein remained unchanged along with integrated ultrastructure on nodule cells for 48 h, whereas in cowpea a decline in proteins with ultrastructural damage became apparent within a very short period of photosynthate stress. In peanut nodules empty or partially empty oleosomes were taken as evidence for their utilization during the stress period. Key words: N2 fixation, photosynthate stress, lipid bodies, catalase, malate synthase, peanut nodule, β-oxidation.

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