scholarly journals New Rhizobium leguminosarum bv. trifolii isolates: Evaluation of competitiveness for clover nodule occupancy

2011 ◽  
Vol 52 (No. 10) ◽  
pp. 441-448 ◽  
Author(s):  
T. Šimon ◽  
J. Salava
Keyword(s):  
Nitrogen Fixation ◽  
Rhizobium Leguminosarum ◽  
Random Amplified Polymorphic Dna ◽  
The Other ◽  
Pot Experiment ◽  
Nodule Occupancy ◽  
Inoculum Level ◽  
Highly Efficient ◽  
Inoculum Dose ◽  
Beginning Of Flowering

An interrelationship between introduced and indigenous rhizobia focused on their competitiveness in nodulation was evaluated in a soil pot experiment. Clover seeds were inoculated by six different gradual concentrations of inoculum of two effective Rhizobium leguminosarum bv. trifolii isolates (inoculation strains 1/2 and 14/2). At the beginning of flowering, clover plants were removed from the pots, and nodules from each pot representing different degrees of inoculum level were taken for reisolate cultivation. The PCR technique was used for the identification of rhizobial reisolates, random amplified polymorphic DNA product patterns were acquired and analysed. Nodule occupation by inoculation strains or indigenous Rhizobium leguminosarum bv. trifolii strains was assessed by comparing the number of nodules formed by inoculation or indigenous strains and inoculation strains competitiveness was calculated. Nodule occupancy by the inoculation strain 1/2 increased sharply with the increase in inoculum dose, whereas in inoculation strain 14/2 more nodules were formed gradually starting from low inoculum level. Competitiveness of inoculation strain 1/2 was calculated as low and was documented by an absence of nodule occupancy in four inoculation levels. On the other hand, competitiveness of the inoculation strain 14/2 was considerably higher, and even in low inoculum dose this strain was more competitive than native rhizobia. Although both the inoculation strains 1/2 and 14/2 were found highly efficient in nitrogen fixation, only the strain 14/2 was able to manifest this characteristic due to the higher competitiveness when applied in lower doses.

Phylogenetic grouping and identification of Rhizobium isolates on the basis of random amplified polymorphic DNA profiles

1993 ◽  
Vol 39 (7) ◽  
pp. 665-673 ◽  
Author(s):  
John J. Dooley ◽  
Stephen P. Harrison ◽  
Lance R. Mytton ◽  
Malcolm Dye ◽  
Ann Cresswell ◽  
...  
Keyword(s):  
Rhizobium Leguminosarum ◽  
Rhizobium Meliloti ◽  
Random Amplified Polymorphic Dna ◽  
Dna Amplification ◽  
Distinct Group ◽  
Principal Coordinate Analysis ◽  
The Other ◽  
Phylogenetic Grouping ◽  
Dna Profiles ◽  
Selection Of

Through the use of a single, random 15mer as a primer, between 1 and 12 DNA amplification products were obtained per strain from a selection of 84 Rhizobium and Bradyrhizobium isolates. A principal-coordinate analysis was used to analyse the resulting amplified DNA profiles and it was possible to assign isolates to specific groupings. Within the species Rhizobium leguminosarum, the biovar phaseoli formed a distinct group from the other biovars of the species, viciae and trifolii, which grouped together. Isolates of Rhizobium meliloti and Bradyrhizobium species formed their own clear, specific groups. Although it was possible to identify individual isolates on the basis of differences in their amplified DNA profiles, there was evidence that some amplified segments were conserved among individuals at the biovar and species levels.Key words: Rhizobium, DNA amplification, random primers.

Highly efficient nitrogen fixation enabled by an atmospheric pressure rotating gliding arc

2021 ◽  
Author(s):  
Hang Chen ◽  
Angjian Wu ◽  
Stéphanie Mathieu ◽  
Peihan Gao ◽  
Xiaodong Li ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Atmospheric Pressure ◽  
Gliding Arc ◽  
Highly Efficient

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.

Efficient Modulation of Catalytic Performance of Electrocatalytic Nitrogen Reduction with Transition Metal Anchored N/O-codoped Graphene by Coordination Engineering

2021 ◽  
Author(s):  
Xiaolin Wang ◽  
Li-Ming Yang
Keyword(s):  
Nitrogen Fixation ◽  
Transition Metal ◽  
High Throughput ◽  
First Principles ◽  
High Throughput Screening ◽  
Catalytic Performance ◽  
Nitrogen Reduction ◽  
Highly Efficient ◽  
First Time

We for the first time report the discovery of a series of highly efficient electrocatalysts, i.e., transition metal anchored N/O-codoped graphene, for nitrogen fixation via high-throughput screening combined with first-principles...

scholarly journals The use of random amplified polymorphic DNA to evaluate the genetic variability of Ponkan mandarin (Citrus reticulata Blanco) accessions

2000 ◽  
Vol 23 (1) ◽  
pp. 169-172 ◽  
Author(s):  
Helvécio Della Coletta Filho ◽  
Marcos Antonio Machado ◽  
M. Luiza P.N. Targon ◽  
Jorgino Pompeu Jr.
Keyword(s):  
Genetic Variability ◽  
Rapd Analysis ◽  
Random Amplified Polymorphic Dna ◽  
Point Mutations ◽  
The Other ◽  
Citrus Reticulata ◽  
Random Primers ◽  
Citrus Reticulata Blanco ◽  
Ponkan Mandarin

RAPD analysis of 19 Ponkan mandarin accessions was performed using 25 random primers. Of 112 amplification products selected, only 32 were polymorphic across five accessions. The absence of genetic variability among the other 14 accessions suggested that they were either clonal propagations with different local names, or that they had undetectable genetic variability, such as point mutations which cannot be detected by RAPD.

scholarly journals Regulation and characterization of mutants of fixABCX in Rhizobium leguminosarum.

2021 ◽  
Author(s):  
Isabel Webb ◽  
Jiabao Xu ◽  
Carmen Sanchez-Cañizares ◽  
Ramakrishnan Karunakaran ◽  
Vinoy Ramachandran ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Rhizobium Leguminosarum ◽  
Redox Balance ◽  
Rna Seq ◽  
Wild Type ◽  
Transcription Start Sites ◽  
Sym Plasmid ◽  
Microaerobic Conditions ◽  
Type Infection

Symbiosis between Rhizobium leguminosarum and Pisum sativum requires tight control of redox balance in order to maintain respiration under the microaerobic conditions required for nitrogenase, whilst still producing the eight electrons and sixteen molecules of ATP needed for nitrogen fixation. FixABCX, electron transfer flavoproteins essential for nitrogen fixation, are encoded on the Sym plasmid (pRL10), immediately upstream of nifA, which encodes the general transcriptional regulator of nitrogen fixation. There is a symbiotically-regulated NifA-dependent promoter upstream of fixA (PnifA1), as well as an additional basal constitutive promoter driving background expression of nifA (PnifA2). These were confirmed by 5’-end mapping of transcription start sites using differential (d) RNA-seq. Complementation of polar fixAB and fixX mutants (Fix- strains) confirmed expression of nifA from PnifA1 in symbiosis. Electron microscopy combined with single-cell Raman microspectroscopy characterization of fixAB mutants revealed previously unknown heterogeneity in bacteroid morphology within a single nodule. Two morphotypes of mutant fixAB bacteroids were observed. One was larger than wild-type bacteroids and contained high levels of polyhydroxy-3-butyrate, a complex energy/reductant storage product. A second bacteroid phenotype was morphologically and compositionally different and resembled wild-type infection thread cells. From these two characteristic fixAB mutant bacteroid morphotypes, inferences can be drawn on the metabolism of wild-type nitrogen-fixing bacteroids.

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