Unusual localization of nod and nif genes in Rhizobium leguminosarum bv. viciae

1997 ◽  
Vol 43 (4) ◽  
pp. 399-402 ◽  
Author(s):  
Sylvie-Isabelle Mazurier ◽  
Gisele Laguerre
Keyword(s):  
Plasmid Dna ◽  
Genomic Dna ◽  
Rhizobium Leguminosarum ◽  
Large Plasmid ◽  
Nif Genes ◽  
Symbiotic Genes ◽  
Nod Genes ◽  
Symbiotic Plasmid ◽  
Wild Strains ◽  
Sym Plasmid

Genomic DNA from seven strains of Rhizobium leguminosarum bv. viciae isolated from nodules of field-grown lentils showed homology to nod and nif gene probes, whereas plasmid DNA did not hybridize with these probes. The results suggest that symbiotic genes could be located on the chromosome or perhaps on a very large plasmid that could not be resolved in Eckhardt gels. Each strain contained one plasmid that hybridized with a pSym isolated from a R. leguminosarum strain of the same field population. This finding led us to hypothesize that the nod and nif genes of the seven strains might have originated from a Sym plasmid and have been integrated into another replicon. The ability to nodulate vetch was confirmed for all of the seven strains. Thus, wild strains of R. leguminosarum bv. viciae that nodulate vetch carry nod and nif genes either on the chromosome or on an extrachromosomal replicon of size much larger than the pSyms hitherto described.Key words: Rhizobium leguminosarum, nod genes, nif genes, chromosome, symbiotic plasmid, megaplasmid.

scholarly journals Symbiotic Plasmid Rearrangement in Rhizobium leguminosarum bv. viciae VF39SM

2001 ◽  
Vol 183 (6) ◽  
pp. 2141-2144 ◽  
Author(s):  
Xue-Xian Zhang ◽  
Bob Kosier ◽  
Ursula B. Priefer
Keyword(s):  
Parent Strain ◽  
Rhizobium Leguminosarum ◽  
Plasmid Profile ◽  
The Other ◽  
Dna Fragments ◽  
Symbiotic Genes ◽  
Symbiotic Plasmid ◽  
Other Hand

ABSTRACT A rearrangement between the symbiotic plasmid (pRleVF39d) and a nonsymbiotic plasmid (pRleVF39b) in Rhizobium leguminosarumbv. viciae VF39 was observed. The rearranged derivative showed the same plasmid profile as its parent strain, but hybridization to nod, fix, and nif genes indicated that most of the symbiotic genes were now present on a plasmid corresponding in size to pRleVF39b instead of pRleVF39d. On the other hand, some DNA fragments originating from pRleVF39b now hybridized to the plasmid band at the position of pRleVF39d. These results suggest that a reciprocal but unequal DNA exchange between the two plasmids had occurred.

Expression of the symbiotic plasmid from Rhizobium leguminosarum biovar trifolii in Sphingobacterium multivorum

1994 ◽  
Vol 40 (10) ◽  
pp. 873-879 ◽  
Author(s):  
M. Fenton ◽  
B. D. W. Jarvis
Keyword(s):  
Gene Transfer ◽  
White Clover ◽  
Microscopic Examination ◽  
Rhizobium Leguminosarum ◽  
Atmospheric Nitrogen ◽  
Symbiotic Genes ◽  
Symbiotic Plasmid ◽  
Spontaneous Transfer ◽  
Inoculant Strain ◽  
Rhizobium Leguminosarum Biovar Trifolii

An inoculant strain of Rhizobium leguminosarum biovar trifolii containing a Tn5 marked symbiotic plasmid transferred this plasmid by conjugation to Sphingobacterium multivorum, an organism that can be found in soil. The transconjugant bacteria nodulated the roots of white clover (Trifolium repens) seedlings but did not fix atmospheric nitrogen. Microscopic examination revealed abnormal nodule structures. Bacteria isolated from the nodules were shown to be closely related to the recipient S. multivorum and Southern blots of genomic digests probed with nodA DNA confirmed that the transconjugants contained symbiotic genes. This is the first report of the spontaneous transfer, by conjugation, of a symbiotic plasmid from R. leguminosarum biovar trifolii to S. multivorum.Key words: Rhizobium, Sphingobacterium, nodulation, nod gene transfer.

Conformity and diversity among field isolates of Rhizobium leguminosarum bv. viciae, bv. trifolii, and bv. phaseoli revealed by DNA hybridization using chromosome and plasmid probes

1993 ◽  
Vol 39 (4) ◽  
pp. 412-419 ◽  
Author(s):  
Gisèle Laguerre ◽  
Eric Geniaux ◽  
Sylvie Isabelle Mazurier ◽  
Raquel Rodriguez Casartelli ◽  
Noëlle Amarger
Keyword(s):  
Host Plant ◽  
Plant Species ◽  
Plasmid Dna ◽  
Dna Hybridization ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Plant Host ◽  
Host Plant Species ◽  
Symbiotic Plasmid ◽  
Chromosomal Type

A study was made of 113 bacterial isolates from root nodules of peas, lentils, red clover, and French beans, which had been grown in the same soil. Plasmid band profiles visualized in Eckhardt gels were analysed in relation to DNA hybridization patterns obtained by probing restricted total cellular DNA in Southern blots. Rhizobium leguminosarum chromosomal probes (plac12, pCOS309.1) and various symbiotic plasmid (nod gene region) probes were used. Dominant plasmid DNA hybridization patterns and more frequent combinations of plasmid patterns and chromosomal types were found among the isolates of each host plant species; the occurrence of alternative combinations indicated that genetic transfer and recombination among members of this soil population had taken place. About 40% of all isolates belonged to the same chromosomal type. Isolates of the same chromosomal type were often found with cryptic plasmids of the same size in different host plant species. Although isolates could not be assigned to their respective plant host groups using chromosomal probes alone, this was generally possible using symbiotic plasmid probes and the results were in complete accordance with plant tests. However, there was a group of bean isolates in which no homology to any of the R. leguminosarum probes was detected under the conditions of high stringency used. Other exceptional isolates of beans conformed in probe tests and subsequent plant host specificity tests better to biovars viciae or trifolii than to biovar phaseoli; thus, the nodulation of beans (i.e., Phaseolus vulgaris) in the field appears less subject to stringent control of specificity than that of other host plant species. It was also noted that the nod gene regions probed showed greater diversity in isolates of biovars viciae and trifolii than in biovar phaseoli.Key words: Rhizobium leguminosarum, genetic diversity, plasmid, DNA hybridization, restriction fragment length polymorphism.

Contribution of the Symbiotic Plasmid to the Competitiveness of Rhizobium leguminosarum

Microbiology ◽  
1983 ◽  
Vol 129 (10) ◽  
pp. 2973-2977 ◽  
Author(s):  
N. J. Brewin ◽  
E. A. Wood ◽  
J. P. W. Young
Keyword(s):  
Rhizobium Leguminosarum ◽  
Symbiotic Plasmid

scholarly journals Distribution of O-acetyl groups in the exopolysaccharide synthesized by Rhizobium leguminosarum strains is not determined by the Sym plasmid

1991 ◽  
Vol 266 (15) ◽  
pp. 9556-9564
Author(s):  
H.C. Cremers ◽  
M. Batley ◽  
J.W. Redmond ◽  
A.H. Wijfjes ◽  
B.J. Lugtenberg ◽  
...  
Keyword(s):  
Rhizobium Leguminosarum ◽  
Sym Plasmid

scholarly journals A paradoxical synergism between Resveratrol and copper (II) with respect to degradation of DNA and RNA

F1000Research ◽  
2015 ◽  
Vol 4 ◽  
pp. 1145 ◽  
Author(s):  
Siddharth Subramaniam ◽  
Iqbal Vohra ◽  
Aishwarya Iyer ◽  
Naveen K Nair ◽  
Indraneel Mittra
Keyword(s):  
Synergistic Effect ◽  
Plasmid Dna ◽  
Genomic Dna ◽  
Oxygen Species ◽  
Molar Ratios ◽  
Dna Cleaving ◽  
Dna And Rna ◽  
Fixed Concentration ◽  
Anti Cancer ◽  
Low Levels

Resveratrol (R), a plant polyphenol, is known to reduce Cu (II) to Cu (I) generating reactive oxygen species that can cleave plasmid DNA. Here we report a surprising observation of a paradoxical synergistic effect between R and Cu whereby plasmid DNA cleaving / degrading activity of R-Cu increased progressively as the ratio of R to Cu was increased i.e., the concentration of Cu was successively reduced with respect to a fixed concentration R. Whereas cleavage of plasmid DNA occurred at low molar ratios of R to Cu, at higher ratios, complete degradation of DNA was achieved. By further increasing the ratio, whereby the concentration of Cu was reduced to very low levels, the DNA degrading activity of R-Cu was lost. This paradoxical synergistic effect is also seen with respect to eukaryotic genomic DNA and RNA. Since R-Cu may have anti-cancer and anti-viral activities, our findings may not only help to improve the therapeutic efficacy of R-Cu but also reduce its toxic side effects with the use of low concentration of Cu.

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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