Nitrogen fixation in legume root nodules: biochemical studies with soybean

1969 ◽  
Vol 172 (1029) ◽  
pp. 401-416 ◽  
Keyword(s):  
Nitrogen Fixation ◽  
Root Nodule ◽  
Root Nodules ◽  
Reducing Power ◽  
Nitrogen Fixing ◽  
Nodule Bacteria ◽  
Stages Of Growth ◽  
Host Cytoplasm ◽  
Photosynthetic Product ◽  
Power And Energy

It is now clear from studies with soybean root nodules that the nitrogen fixing activity resides in the bacteroids which are the symbiotic form of the root nodule bacteria. These develop as a result of a complex series of changes in metabolism and structure which occur in the bacteria during the final stages of growth within membrane-enclosed vesicles in the host cytoplasm. Nitrogenase appears when these changes are complete. The primary product of nitrogen fixation is NH 3 , which in intact nodules, is rapidly transformed into α -amino compounds which are used by the host plant. In suspensions of bacteroids and in cell-free extracts prepared from them, the reaction terminates in NH 3 , which is released into the medium. Free O 2 , which is required for the production of energy for nitrogen fixation by nodules and by bacteroid suspensions, also causes inactivation of the nitrogen fixing system and exerts important kinetic influences upon the reaction. Reducing power and energy for the reduction of N 2 to NH 3 is provided by a photosynthetic product from the host in nodules; in bacteroid suspensions, a substrate such as succinate is required. In cell-free extracts, requirements for energy and reductant are met by ATP and dithionite. The natural reductant has not yet been identified. A schematic representation of various factors which affect nitrogen fixation in nodules, bacteroid suspensions and cell-free extracts is presented.

scholarly journals Expression Map for Genes Involved in Nitrogen and Carbon Metabolism in Alfalfa Root Nodules

1999 ◽  
Vol 12 (6) ◽  
pp. 526-535 ◽  
Author(s):  
Gian B. Trepp ◽  
Stephen J. Temple ◽  
Bruna Bucciarelli ◽  
Li Fang Shi ◽  
Carroll P. Vance
Keyword(s):  
Nitrogen Fixation ◽  
Glutamine Synthetase ◽  
Carbon Metabolism ◽  
Root Nodule ◽  
Root Nodules ◽  
Constitutive Expression ◽  
Nodule Development ◽  
Relative Distribution ◽  
Nitrogen Fixing ◽  
Alfalfa Root

During root nodule development several key genes involved in nitrogen fixation and assimilation exhibit enhanced levels of expression. However, little is known about the temporal and spatial distribution patterns of these transcripts. In a systematic study the transcripts for 13 of the essential enzymes involved in alfalfa (Medicago sativa) root nodule nitrogen and carbon metabolism were localized by in situ hybridization. A serial section approach allowed the construction of a map that reflects the relative distribution of these transcripts. In 33-day-old root nodules, the expression of nifH, NADH-dependent glutamate synthase (NADH-GOGAT; EC 1.4.1.14) and a cytosolic isoform of glutamine synthetase (GS13; GS; EC 6.3.1.2) were localized predominantly in a 5- to 15-cell-wide region in the distal part of the nitrogen-fixing zone. This zone was also the region of high expression for leghemoglobin, a second cytosolic glutamine synthetase isoform (GS100), aspartate aminotransferase-2 (AAT-2; EC 2.6.1.1), asparagine synthetase (AS; 6.3.5.4), phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31), and sucrose synthase (SuSy; EC 2.4.1.13). This suggests that, in 33-day-old alfalfa root nodules, nitrogen fixation is restricted to this 5- to 15-cell-wide area. The continued significant expression of the GS100 subclass of GS and AS in the proximal part of the nitrogen-fixing zone implicates these gene products in nitrogen remobilization. A low constitutive expression of NADH-dependent glutamate dehydrogenase (NADH-GDH; EC 1.4.1.2) was observed throughout the nodule. The transcript distribution map will be used as a navigational tool to assist in developing strategies for the genetic engineering of alfalfa root nodules for enhanced nitrogen assimilation.

scholarly journals A New Species of Devosia That Forms a Unique Nitrogen-Fixing Root-Nodule Symbiosis with the Aquatic Legume Neptunia natans (L.f.) Druce

2002 ◽  
Vol 68 (11) ◽  
pp. 5217-5222 ◽  
Author(s):  
Raul Rivas ◽  
Encarna Velázquez ◽  
Anne Willems ◽  
Nieves Vizcaíno ◽  
Nanjappa S. Subba-Rao ◽  
...  
Keyword(s):  
Root Nodule ◽  
Root Nodules ◽  
Infection Process ◽  
Nitrogen Fixing ◽  
Rhizobium Tropici ◽  
Rdna Sequences ◽  
Root Nodule Symbiosis ◽  
16S Rdna Sequences ◽  
The Common ◽  
Nodule Symbiosis

ABSTRACT Rhizobia are the common bacterial symbionts that form nitrogen-fixing root nodules in legumes. However, recently other bacteria have been shown to nodulate and fix nitrogen symbiotically with these plants. Neptunia natans is an aquatic legume indigenous to tropical and subtropical regions and in African soils is nodulated by Allorhizobium undicola. This legume develops an unusual root-nodule symbiosis on floating stems in aquatic environments through a unique infection process. Here, we analyzed the low-molecular-weight RNA and 16S ribosomal DNA (rDNA) sequence of the same fast-growing isolates from India that were previously used to define the developmental morphology of the unique infection process in this symbiosis with N. natans and found that they are phylogenetically located in the genus Devosia, not Allorhizobium or Rhizobium. The 16S rDNA sequences of these two Neptunia-nodulating Devosia strains differ from the only species currently described in that genus, Devosia riboflavina. From the same isolated colonies, we also located their nodD and nifH genes involved in nodulation and nitrogen fixation on a plasmid of approximately 170 kb. Sequence analysis showed that their nodD and nifH genes are most closely related to nodD and nifH of Rhizobium tropici, suggesting that this newly described Neptunia-nodulating Devosia species may have acquired these symbiotic genes by horizontal transfer.

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.

Distribution, frequency of occurrence and symbiotic properties of the Australian native legume Trigonella suavissima Lindl. and its associated root-nodule bacteria

2010 ◽  
Vol 32 (4) ◽  
pp. 395 ◽  
Author(s):  
J. Brockwell ◽  
Catherine M. Evans ◽  
Alison M. Bowman ◽  
Alison McInnes
Keyword(s):  
Root Nodule ◽  
Clay Soils ◽  
Frequency Of Occurrence ◽  
Nitrogen Fixing ◽  
Nodule Bacteria ◽  
River Systems ◽  
Root Nodule Bacteria ◽  
North East ◽  
Inland River ◽  
Native Legume

Trigonella suavissima Lindl. is an Australian native legume belonging to the tribe Trifolieae. It is an ephemeral species that is widely distributed in the arid interior of the continent where it occurs, following periodic inundation, on clay soils of the watercourse country of the Channel Country (far-western Queensland, north-east South Australia and north-western New South Wales). T. suavissima is the only member of its tribe that is endemic to Australia. Likewise, its root-nodule bacteria (Sinorhizobium sp.) may be the only member of its taxonomic group (S. meliloti, S. medicae) that is an Australian native. The distribution and frequency of occurrence of T. suavissima and the size of soil populations (density) of Sinorhizobium were monitored at 64 locations along inland river systems of the Channel Country. Measurements were made of (i) the nitrogen-fixing effectiveness of the symbioses between T. suavissima and strains of its homologous Sinorhizobium and (ii) the nitrogen-fixing effectiveness of the symbioses between legumes symbiotically related to T. suavissima and diverse strains of Sinorhizobium. It was concluded that the distribution and frequency of occurrence of T. suavissima is soil related. The species is most widespread on fine-textured clay soils with deep, self-mulching surfaces and high moisture-holding capacity. By contrast, the occurrence of T. suavissima is sporadic in the upper reaches of the inland river systems where the soils are poorly structured clays with lower moisture-holding capacity. Sinorhizobium is most abundant where the plant is most common. The nitrogen-fixing symbioses between T. suavissima and strains of Sinorhizobium isolated from soils across the region were consistently effective and often highly effective. Some of these strains fixed a little nitrogen with lucerne (Medicago sativa L.). T. suavissima also had some symbiotic (nitrogen-fixing) affinity with an exotic Trigonella (T. arabica Del.). The economic value of T. suavissima (and its symbiosis with Sinorhizobium) to the beef industry in the Channel Country is discussed.

scholarly journals FrankiaDiversity in Host Plant Root Nodules Is Independent of Abundance or Relative Diversity ofFrankiaPopulations in Corresponding Rhizosphere Soils

2017 ◽  
Vol 84 (5) ◽  
Author(s):  
Seifeddine Ben Tekaya ◽  
Trina Guerra ◽  
David Rodriguez ◽  
Jeffrey O. Dawson ◽  
Dittmar Hahn
Keyword(s):  
Host Plant ◽  
Root Nodule ◽  
Root Nodules ◽  
Actinorhizal Plants ◽  
Nodule Formation ◽  
Nitrogen Fixing ◽  
Content Type ◽  
Rhizosphere Soils ◽  
Root Nodule Formation ◽  
Host Infection

ABSTRACTActinorhizal plants form nitrogen-fixing root nodules in symbiosis with soil-dwelling actinobacteria within the genusFrankia, and specificFrankiataxonomic clusters nodulate plants in corresponding host infection groups. In same-soil microcosms, we observed that some host species were nodulated (Alnus glutinosa,Alnus cordata,Shepherdia argentea,Casuarina equisetifolia) while others were not (Alnus viridis,Hippophaë rhamnoides). Nodule populations were represented by eight different sequences ofnifHgene fragments. Two of these sequences characterized frankiae inS. argenteanodules, and three others characterized frankiae inA. glutinosanodules. Frankiae inA. cordatanodules were represented by five sequences, one of which was also found in nodules fromA. glutinosaandC. equisetifolia, while another was detected in nodules fromA. glutinosa. Quantitative PCR assays showed that vegetation generally increased the abundance of frankiae in soil, independently of the target gene (i.e.,nifHor the 23S rRNA gene). Targeted Illumina sequencing ofFrankia-specificnifHgene fragments detected 24 unique sequences from rhizosphere soils, 4 of which were also found in nodules, while the remaining 4 sequences in nodules were not found in soils. Seven of the 24 sequences from soils represented >90% of the reads obtained in most samples; the 2 most abundant sequences from soils were not found in root nodules, and only 2 of the sequences from soils were detected in nodules. These results demonstrate large differences between detectableFrankiapopulations in soil and those in root nodules, suggesting that root nodule formation is not a function of the abundance or relative diversity of specificFrankiapopulations in soils.IMPORTANCEThe nitrogen-fixing actinobacteriumFrankiaforms root nodules on actinorhizal plants, with members of specificFrankiataxonomic clusters nodulating plants in corresponding host infection groups. We assessedFrankiadiversity in root nodules of different host plant species, and we related specific populations to the abundance and relative distribution of indigenous frankiae in rhizosphere soils. Large differences were observed between detectableFrankiapopulations in soil and those in root nodules, suggesting that root nodule formation is not a function of the abundance or relative diversity of specificFrankiapopulations in soils but rather results from plants potentially selecting frankiae from the soil for root nodule formation. These data also highlight the necessity of using a combination of different assessment tools so as to adequately address methodological constraints that could produce contradictory data sets.

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 Loss of the nodule-specific cysteine rich peptide, NCR169, abolishes symbiotic nitrogen fixation in the Medicago truncatula dnf7 mutant

2015 ◽  
Vol 112 (49) ◽  
pp. 15232-15237 ◽  
Author(s):  
Beatrix Horváth ◽  
Ágota Domonkos ◽  
Attila Kereszt ◽  
Attila Szűcs ◽  
Edit Ábrahám ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Medicago Truncatula ◽  
Symbiotic Nitrogen Fixation ◽  
Root Nodules ◽  
Nitrogen Fixing ◽  
In Planta ◽  
Functional Roles ◽  
Absolute Requirement ◽  
Cell Layers

Host compatible rhizobia induce the formation of legume root nodules, symbiotic organs within which intracellular bacteria are present in plant-derived membrane compartments termed symbiosomes. In Medicago truncatula nodules, the Sinorhizobium microsymbionts undergo an irreversible differentiation process leading to the development of elongated polyploid noncultivable nitrogen fixing bacteroids that convert atmospheric dinitrogen into ammonia. This terminal differentiation is directed by the host plant and involves hundreds of nodule specific cysteine-rich peptides (NCRs). Except for certain in vitro activities of cationic peptides, the functional roles of individual NCR peptides in planta are not known. In this study, we demonstrate that the inability of M. truncatula dnf7 mutants to fix nitrogen is due to inactivation of a single NCR peptide, NCR169. In the absence of NCR169, bacterial differentiation was impaired and was associated with early senescence of the symbiotic cells. Introduction of the NCR169 gene into the dnf7-2/NCR169 deletion mutant restored symbiotic nitrogen fixation. Replacement of any of the cysteine residues in the NCR169 peptide with serine rendered it incapable of complementation, demonstrating an absolute requirement for all cysteines in planta. NCR169 was induced in the cell layers in which bacteroid elongation was most pronounced, and high expression persisted throughout the nitrogen-fixing nodule zone. Our results provide evidence for an essential role of NCR169 in the differentiation and persistence of nitrogen fixing bacteroids in M. truncatula.

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.

scholarly journals The reaction of self-fertile alfalfa lines to inoculation with nodule bacteria

2020 ◽  
Keyword(s):  
Nitrogen Fixation ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Growing Season ◽  
Dry Mass ◽  
Nodule Bacteria ◽  
Forage Crop ◽  
Nitrogen Fixation Activity ◽  
Fixation Activity ◽  
Different Strains

Under the conditions of a model pot experiments, the reaction of the self-fertile lines of alfalfa Kishvardy 46, Kishvardy 27, Vertus and Ziguen to inoculation with nodule bacteria Sinorhizobium meliloti AC48 and AC88 was studied. As a result of studies, it was found that the intensity of assimilation of N2 by symbiotic systems created with the participation of various genotypes of alfalfa and active strains of S. meliloti is one of the main factors that affects the vegetative mass yield of this important forage crop. Self-fertile lines of Medicago sativa L. plants, inoculated with different strains of rhizobia were characterized by higher rates of the mass formed on the root nodules, compared to the control plants of the alfalfa variety Yaroslavna. The traditional dynamics of nitrogen-fixation activity of root nodules was maintained in all the symbiotic systems studied by us, with low values in the stems formation stage and intensive growth in the budding and flowering stages. The highest level of nitrogen fixation and vegetative growth of plants (values of plants green and dry mass, roots and root nodules mass) was established by inoculation of alfalfa line Kishvardy 46 with strain S. meliloti AC48. During the growing season the indices of the mass of nodules formed on the roots of these plants were higher by 1.8–2.3 times, the green mass by 1.2–1.6 times and the height of the plants 1.2–1.4 times as compared to the control. In the flowering stages the nitrogen-fixation activity of the symbiotic complex of plants of the Kishvardy line 27 and nodule bacteria S. meliloti AC48 exceeded the values in the symbiotic systems formed with the participation of the same strain and plants of the Ziguen and Vertus lines by 13.0 and 39.4 %. The lowest values of nitrogen fixation activity were observed by inoculation of plants of the Vertus and Ziguen lines with active strains S. meliloti AC48 and AC88 compared to the symbioses formed by the plants of the Kishvardy lines 27 and 46, as well as of the control-variety Yaroslavna with the noted strains. A stimulating effect of inoculation of alfalfa seeds of different genotypes on the growth and development of plants was noted, as evidenced by the positive dynamics of the increase in above-ground mass, the accumulation of dry matter and higher than the control values (indicators) of plant height during the growing season.

STUDY OF THE BIOCOMPATIBILITY OF MUTANT STRAINS OF ROOT NODULE AND PGPR BACTERIA, PROMISING AS A BASIS OF MICROBIAL PREPARATIONS

2021 ◽  
Author(s):  
О.Н. ШЕМШУРА ◽  
Ж.Б. СУЛЕЙМЕНОВА ◽  
Ж.К. РАХМЕТОВА ◽  
Ж.Н. ШЕМШЕЕВА ◽  
Э.Т. ИСМАИЛОВА
Keyword(s):  
Bacillus Subtilis ◽  
Pseudomonas Putida ◽  
Mung Bean ◽  
Root Nodule ◽  
Nitrogen Fixing ◽  
Nodule Bacteria ◽  
Biological Product ◽  
Bean Plants ◽  
Combined Use ◽  
Mutant Strains

В статье приведены результаты исследования биосовместимости мутантных штаммов клубеньковых и PGPR бактерий (ризобактерий) с целью их совместного применения для культур маша и фасоли. По результатам проведенных исследований определены штаммы, проявившие контактную прогрессию и нейтралитет - Pseudomonas putidaМ-1 и Phyllobacterium sp. 35М; штаммы Bacillus subtilis М-2 и Chryseobacterium rhizoplanae 1М оказались наиболее перспективными в отношении совместного культивирования.Таким образом, подобраны консорциумы на основе мутантных штаммов азотфиксирующих и ростостимулирующих бактерий Pseudomonas putida М-1 и Chryseobacterium rhizoplanae для растений маша и Bacillus subtilis М-2 и Phyllobacterium sp. 35М - для растений фасоли. Полученные результаты открывают возможность комбинирования мутантных штаммов PGPR с ростостимулирующей активностью (Pseudomonas putida М-1, Bacillus subtilis М-2) и клубеньковыхбактерий (Phyllobacterium sp. 35М, Chryseobacterium rhizoplanae) с азотфиксирующей активностью с целью получения на их основе биопрепарата с сочетанными свойствами. The article presents the results of a study of the biocompatibility of mutant strains of nodule and PGPR bacteria with the aim of their combined use for mung bean and beans. According to the results of the studies, the strains that showed contact progression and neutrality were identified - Pseudomonas putida M-1 and Phyllobacterium sp. 35M; strains Bacillus subtilis M-2 and Chryseobacterium rhizoplanae 1M proved to be the most promising for co-cultivation. Thus, consortia were selected based on mutant strains of nitrogen-fixing and growth-stimulating bacteria Pseudomonas putida M-1 and Chryseobacterium rhizoplanae for mung bean and Bacillus subtilis M-2 and Phyllobacterium sp.35M for bean plants. The results obtained open up the possibility of combining mutant PGPR strains with growth-stimulating activity (Pseudomonas putida M-1, Bacillus subtilis M-2) and nodule bacteria with nitrogen-fixing activity (Phyllobacterium sp. 35M, Chryseobacterium rhizoplanae) in order to obtain a biological product with combined properties on their basis.

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