scholarly journals Relationship between root nodule nitrogen fixation of leguminous plants and oxygen.

Root Research ◽  
1996 ◽  
Vol 5 (3) ◽  
pp. 70-73 ◽  
Author(s):  
Shinji SHIMADA
Keyword(s):  
Nitrogen Fixation ◽  
Root Nodule ◽  
Leguminous Plants

Bradyrhizobium japonicum mutants defective in root-nodule bacteroid development and nitrogen fixation

1986 ◽  
Vol 144 (4) ◽  
pp. 355-366 ◽  
Author(s):  
B. Regensburger ◽  
L. Meyer ◽  
M. Filser ◽  
J. Weber ◽  
D. Studer ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Bradyrhizobium Japonicum ◽  
Root Nodule

Investigations on the root nodule bacteria of leguminous plants: XIX. Influence of various factors on the excretion of nitrogenous compounds from the nodules

1937 ◽  
Vol 27 (3) ◽  
pp. 332-348 ◽  
Author(s):  
Artturi Ilmari Virtanen ◽  
Synnöve von Hausen ◽  
Tauno Laine
Keyword(s):  
Amino Acids ◽  
Nitrogen Fixation ◽  
Root Nodule ◽  
Nitrogen Nutrition ◽  
Nitrogen Compounds ◽  
Nodule Bacteria ◽  
Fixed Nitrogen ◽  
Nitrogenous Compounds ◽  
Primary Products ◽  
Equal Effectiveness

1. It has been shown experimentally that the excretion of nitrogen noted by us in cultures of inoculated legumes takes place from the nodule bacteria, probably from the intranodular ones, and not from the roots. No excretion of amino acids occurs in cultures of uninoculated legumes growing on nitrate nitrogen.2. Our earlier hypothesis that the legumes receive their nitrogen nutrition from the nodules in the form of organic nitrogen compounds, particularly amino acids, is in perfect accord with our new observations concerning the process of excretion. All facts indicate that the amino acids concerned are primary products of the nitrogen fixation, and not breakdown products of proteins. Bond's valuable work along quite different lines produced results which support this conclusion. He, however, did not study the chemical nature of the nitrogen compounds in question.3. The excretion of nitrogen occurs in media capable of absorbing the excreted nitrogen compounds (cellulose, kaolin, sand, soil). The demonstration of the excretion is not possible in water cultures except when very large quantities of water are used. On the basis of these facts a hypothesis is advanced to explain the nature of the excretion.4. The term total fixed nitrogen has been used as an expression for the extent of nitrogen fixation, while the term extent of excretion is employed to indicate that percentage of the total fixed nitrogen which is excreted from the nodules.5. The extent of excretion depends largely on the strain used for inoculation. With strains of apparently equal effectiveness in nitrogen fixation, the extent of excretion may vary considerably, so that actually such strains differ in their effectiveness.

A STUDY OF THE DISTRIBUTION AND THE EFFECTS OF BACTERIOPHAGE OF ROOT NODULE BACTERIA IN THE SOIL

1957 ◽  
Vol 3 (2) ◽  
pp. 171-180 ◽  
Author(s):  
Janina Kleczkowska
Keyword(s):  
Nitrogen Fixation ◽  
Root Nodule ◽  
Surrounding Medium ◽  
Antigenic Structure ◽  
Bacterial Strains ◽  
Nodule Bacteria ◽  
Root Nodule Bacteria ◽  
Bacterial Mutants ◽  
Resistant Mutants ◽  
Bacterial Mixtures

Bacteriophage for clover nodule bacteria can be found on roots and nodules of all naturally grown clover plants and also in the soil surrounding the roots, but not in soil without clover plants. Alternative hosts for the phage of clover bacteria are pea bacteria, and vice versa. The bacteria and the phage are heterogeneous in the sense that only a proportion of strains of clover bacteria and of pea bacteria are susceptible to lysis by a given race of phage, and only a proportion of races of phage can lyse a given bacterial strain. There does not seem to be any association between the susceptibility of bacterial strains to lysis by phage and any other features such as antigenic structure and effectiveness in nitrogen fixation. There may be an association with avirulence, i.e. inability to infect the host plant. The behavior of phage–bacterial mixtures depends on the surrounding medium. The longevity of phage in soil or in a soil-like medium such as a vermiculite mixture is relatively short, and the effect of phage can be localized so that phage-susceptible bacteria and the phage can exist close to each other without any apparent interaction. However, as long as the phage is present, phage-resistant bacterial mutants are usually present also. The phage-resistant mutants may also be mutants in other respects such as effectiveness in nitrogen fixation. In the presence of weakened phage, bacterial mutants were found to occur that differ from the parent form in effectiveness but resemble it in susceptibility to the phage.

scholarly journals How rhizobia adapt to the nodule environment

2021 ◽  
Author(s):  
Raphael Ledermann ◽  
Carolin C. M. Schulte ◽  
Philip S. Poole
Keyword(s):  
Nitrogen Fixation ◽  
Soil Bacteria ◽  
Root Nodule ◽  
Computational Modelling ◽  
Diverse Group ◽  
Nitrogen Fixing ◽  
The Core ◽  
Physiological Processes ◽  
Mutualistic Relationship ◽  
The Common

Rhizobia are a phylogenetically diverse group of soil bacteria that engage in mutualistic interactions with legume plants. Although specifics of the symbioses differ between strains and plants, all symbioses ultimately result in the formation of specialized root nodule organs which host the nitrogen-fixing microsymbionts called bacteroids. Inside nodules, bacteroids encounter unique conditions that necessitate global reprogramming of physiological processes and rerouting of their metabolism. Decades of research have addressed these questions using genetics, omics approaches, and more recently computational modelling. Here we discuss the common adaptations of rhizobia to the nodule environment that define the core principles of bacteroid functioning. All bacteroids are growth-arrested and perform energy-intensive nitrogen fixation fueled by plant-provided C4-dicarboxylates at nanomolar oxygen levels. At the same time, bacteroids are subject to host control and sanctioning that ultimately determine their fitness and have fundamental importance for the evolution of a stable mutualistic relationship.

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