scholarly journals Identification and characterization of the Rhizobium meliloti ntrC gene: R. meliloti has separate regulatory pathways for activation of nitrogen fixation genes in free-living and symbiotic cells.

1987 ◽  
Vol 169 (4) ◽  
pp. 1423-1432 ◽  
Author(s):  
W W Szeto ◽  
B T Nixon ◽  
C W Ronson ◽  
F M Ausubel
Keyword(s):  
Nitrogen Fixation ◽  
Rhizobium Meliloti ◽  
Free Living ◽  
Regulatory Pathways ◽  
Identification And Characterization ◽  
Nitrogen Fixation Genes

Expression of the nodulation and nitrogen fixation genes in Rhizobium meliloti during development

Genome ◽  
1989 ◽  
Vol 31 (1) ◽  
pp. 354-360 ◽  
Author(s):  
San Chiun Shen ◽  
Shui Ping Wang ◽  
Guan Qiao Yu ◽  
Jia Bi Zhu
Keyword(s):  
Nitrogen Fixation ◽  
Rhizobium Meliloti ◽  
Abnormal Development ◽  
Wild Type ◽  
Free Living ◽  
Nod Genes ◽  
Nodule Initiation ◽  
Fix Genes ◽  
Nitrogen Fixation Genes

Genes that specify nodulation (nod genes) are only active in the free-living rhizobia or in the nodule initiation state of rhizobia. As soon as the repression of nod genes occurs in the bacteroids of the nodule, nifA is induced, while ntrC is inactivated and thus the nifA-mediated nif/fix genes are turned on. Limitation of available oxygen brings about the induction of nifA, which reflects the actual status of nif/fix gene activities in symbiotic state of rhizobia. Oxygen thus appears to be a major symbiotic signal to the expression of bacteroid nif/fix genes. Mutation of nifA or shortage of nifA product in wild-type rhizobia caused by the inhibition of multicopy nifH/fixA promoters leads to an abnormal development of nodules and premature degradation of bacteroids in nodules.Key words: nitrogen fixation, nodulation, nif/fix regulation, nifA mutant.

scholarly journals Novel European free-living, non-diazotrophic Bradyrhizobium isolates from contrasting soils that lack nodulation and nitrogen fixation genes – a genome comparison

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Frances Patricia Jones ◽  
Ian M. Clark ◽  
Robert King ◽  
Liz J. Shaw ◽  
Martin J. Woodward ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Genome Comparison ◽  
Free Living ◽  
A Genome ◽  
Nitrogen Fixation Genes

Identification and characterization of insertion sequence ISRm1 in Rhizobium meliloti JJ1c10

1987 ◽  
Vol 33 (4) ◽  
pp. 314-321 ◽  
Author(s):  
Roger Wheatcroft ◽  
Robert J. Watson
Keyword(s):  
High Frequency ◽  
Insertion Sequence ◽  
Symbiotic Nitrogen Fixation ◽  
Rhizobium Meliloti ◽  
Base Pairs ◽  
Target Region ◽  
Meliloti Strain ◽  
Nodc Gene ◽  
Identification And Characterization

ISRm1, an insertion sequence present in Rhizobium meliloti strain 1021, has been identified as the cause of the Nod− phenotypes in two mutants of another strain, JJ1c10. The insertions were found to be at different sites, though only about 100 base pairs apart within the nodC gene. ISRm1 causes no mutations in the nifHDK gene region of strain JJ1c10, as it does at high frequency in strain 1021. In JJ1c10 ISRm1 inserted at high frequency into a region of the genome adjacent to copies of other reiterated DNA segments. The target region was not required for symbiotic nitrogen fixation.

Mobilization of a Rhizobium meliloti megaplasmid carrying nodulation and nitrogen fixation genes into other rhizobia and Agrobacterium

1982 ◽  
Vol 188 (3) ◽  
pp. 433-439 ◽  
Author(s):  
A. Kondorosi ◽  
E. Kondorosi ◽  
C. E. Pankhurst ◽  
W. J. Broughton ◽  
Z. Banfalvi
Keyword(s):  
Nitrogen Fixation ◽  
Rhizobium Meliloti ◽  
Nitrogen Fixation Genes
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