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 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.

scholarly journals Genome Sequence of Bradyrhizobium tropiciagri Strain CNPSo 1112 T , Isolated from a Root Nodule of Neonotonia wightii

2015 ◽  
Vol 3 (6) ◽  
Author(s):  
Jakeline Renata Marçon Delamuta ◽  
Douglas Fabiano Gomes ◽  
Renan Augusto Ribeiro ◽  
Ligia Maria Oliveira Chueire ◽  
Renata Carolini Souza ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Stress Tolerance ◽  
Genome Sequence ◽  
Root Nodule ◽  
Draft Genome ◽  
Uptake Hydrogenase ◽  
Nitrogen Fixing ◽  
Circular Chromosome ◽  
Coding Sequences ◽  
Large Genome

CNPSo 1112 T is a nitrogen-fixing symbiont of perennial soybean, a tropical legume forage. Its draft genome indicates a large genome with a circular chromosome and 9,554 coding sequences (CDSs). Operons of nodulation, nitrogen fixation, and uptake hydrogenase were present in the symbiotic island, and the genome encompasses several CDSs of stress tolerance.

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.

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 The importance of Rhizobium, Agrobacterium, Bradyrhizobium, Herbaspirillum, Sinorhizobium in sustainable agricultural production

2021 ◽  
Vol 49 (3) ◽  
pp. 12183
Author(s):  
Mohamad H. SHAHRAJABIAN ◽  
Wenli SUN ◽  
Qi CHENG
Keyword(s):  
Nitrogen Fixation ◽  
Cell Division ◽  
Nitrogen Content ◽  
Root Hair ◽  
Agricultural Production ◽  
Soil Bacteria ◽  
Organic Nitrogen ◽  
Nitrogen Fixing ◽  
Review Of The Literature ◽  
Nod Factor

Rhizobia which are soil bacteria capable of symbiosis with legume plants in the root or stem nodules and perform nitrogen fixation. Rhizobial genera include Agrobacterium, Allorhizobium, Aminobacter, Azorhizobium, Bradyrhizobium, Devosia, Mesorhizobium, Methylobacterium, Microvirga, Ochrobacterum, Phyllobacterium, Rhizobium, Shinella and Ensifer (Sinorhizobium). Review of the literature was carried out using the keywords Rhizobium, Agrobacterium, Bradyrhizobium, Herbaspirillum and Sinorhizobium. Rhizobial nodulation symbioses steps are included flavonoid signaling, Nod factor induction, and Nod factor perception, root hair responses, rhizobial infection, cell division and formation of nitrogen-fixing nodule. Rhizobium improves sustainable production by boosting organic nitrogen content.

scholarly journals Pangenomics of the Symbiotic Rhizobiales. Core and Accessory Functions Across a Group Endowed with High Levels of Genomic Plasticity

2021 ◽  
Vol 9 (2) ◽  
pp. 407
Author(s):  
Riccardo Rosselli ◽  
Nicola La Porta ◽  
Rosella Muresu ◽  
Piergiorgio Stevanato ◽  
Giuseppe Concheri ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Core Genome ◽  
Reference Genome ◽  
Ammonia Nitrogen ◽  
Nitrogen Fixing ◽  
Genomic Plasticity ◽  
The Core ◽  
Core Proteins ◽  
Protein Functions ◽  
Core Genes

Pangenome analyses reveal major clues on evolutionary instances and critical genome core conservation. The order Rhizobiales encompasses several families with rather disparate ecological attitudes. Among them, Rhizobiaceae, Bradyrhizobiaceae, Phyllobacteriacreae and Xanthobacteriaceae, include members proficient in mutualistic symbioses with plants based on the bacterial conversion of N2 into ammonia (nitrogen-fixation). The pangenome of 12 nitrogen-fixing plant symbionts of the Rhizobiales was analyzed yielding total 37,364 loci, with a core genome constituting 700 genes. The percentage of core genes averaged 10.2% over single genomes, and between 5% to 7% were found to be plasmid-associated. The comparison between a representative reference genome and the core genome subset, showed the core genome highly enriched in genes for macromolecule metabolism, ribosomal constituents and overall translation machinery, while membrane/periplasm-associated genes, and transport domains resulted under-represented. The analysis of protein functions revealed that between 1.7% and 4.9% of core proteins could putatively have different functions.

Ahara as Pathya and Apathya in Amlapitta - A Review.

2017 ◽  
Vol 2 (1) ◽  
Author(s):  
Rakshith . ◽  
Shivakumar . ◽  
Sreeharsha . ◽  
Divyasree .
Keyword(s):  
Physical Health ◽  
Review Article ◽  
The Other ◽  
Social Health ◽  
Present Review ◽  
Common Disease ◽  
The Core ◽  
Common Disorder ◽  
The Common

The core principles in Ayurveda give prime importance to Agni, Prakriti, Ahara (food) and Vihara (lifestyle) in maintaining health. Present era people are scheduled to one or the other works due to which they are following unrightful food and habits which lead the manifestation of one of the common disorder which troubles person a lot - Amlapitta. By excess “Hurry, Worry and Curry” GIT disorders are the most common, not only affecting physical health but also psychological and social health. Amlapitta is one of that and it is a burning problem of the whole World. Amalpitta is composed of word Amla and Pitta. Amlapitta is a very common disease caused by Vidagdha Pitta with features like Amlodgara, Tiktodgara, Hrit, Kantha Daha etc. Pathya recommended in Amlapitta are Yava, Godhuma, Purana Shali, Mudga Yusha, Lajasaktu etc. Apathya recommended in Amlapitta are Navanna, Avidugdha, Masha, Kulattha, Dadhi and etc. So this present review article throws light on Pathya (conducive) and Apathya (non conducive) in Amlapitta.

The Logicism of Frege, Dedekind, and Russell

2009 ◽  
Author(s):  
William Demopoulos ◽  
Peter Clark
Keyword(s):  
A Priori ◽  
The Core ◽  
Common Thread ◽  
Synthetic A Priori ◽  
The Common

This article is organized around logicism's answers to the following questions: What is the basis for our knowledge of the infinity of the numbers? How is arithmetic applicable to reality? Why is reasoning by induction justified? Although there are, as is seen in this article, important differences, the common thread that runs through all three of the authors discussed in this article their opposition to the Kantian thesis that reflection on reasoning with mere concepts (i.e., without attention to intuitions formed a priori) can never succeed in providing satisfactory answers to these three questions. This description of the core of the view differs from more usual formulations which represent the opposition to Kant as an opposition to the contention that mathematics in general, and arithmetic in particular, are synthetic a priori rather than analytic.

scholarly journals Plasmids Related to the Symbiotic Nitrogen Fixation Are Not Only Cooperated Functionally but Also May Have Evolved over a Time Span in Family Rhizobiaceae

2020 ◽  
Vol 12 (11) ◽  
pp. 2002-2014
Author(s):  
Ling-Ling Yang ◽  
Zhao Jiang ◽  
Yan Li ◽  
En-Tao Wang ◽  
Xiao-Yang Zhi
Keyword(s):  
Nitrogen Fixation ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Symbiotic Nitrogen Fixation ◽  
Gene Families ◽  
Time Span ◽  
Soil Conditions ◽  
Gene Gain ◽  
Nitrogen Fixing ◽  
Pan Genome

Abstract Rhizobia are soil bacteria capable of forming symbiotic nitrogen-fixing nodules associated with leguminous plants. In fast-growing legume-nodulating rhizobia, such as the species in the family Rhizobiaceae, the symbiotic plasmid is the main genetic basis for nitrogen-fixing symbiosis, and is susceptible to horizontal gene transfer. To further understand the symbioses evolution in Rhizobiaceae, we analyzed the pan-genome of this family based on 92 genomes of type/reference strains and reconstructed its phylogeny using a phylogenomics approach. Intriguingly, although the genetic expansion that occurred in chromosomal regions was the main reason for the high proportion of low-frequency flexible gene families in the pan-genome, gene gain events associated with accessory plasmids introduced more genes into the genomes of nitrogen-fixing species. For symbiotic plasmids, although horizontal gene transfer frequently occurred, transfer may be impeded by, such as, the host’s physical isolation and soil conditions, even among phylogenetically close species. During coevolution with leguminous hosts, the plasmid system, including accessory and symbiotic plasmids, may have evolved over a time span, and provided rhizobial species with the ability to adapt to various environmental conditions and helped them achieve nitrogen fixation. These findings provide new insights into the phylogeny of Rhizobiaceae and advance our understanding of the evolution of symbiotic nitrogen fixation.

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