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Isolation and characterization of symbiotic mutants of bradyrhizobium sp. (arachis) strain NC92: mutants with host-specific defects in nodulation and nitrogen fixation

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http://jb.asm.org/cgi/reprint/169/5/2177.pdf
 
Title Isolation and characterization of symbiotic mutants of bradyrhizobium sp. (arachis) strain NC92: mutants with host-specific defects in nodulation and nitrogen fixation
 
Creator Wilson, K J
Anjaiah, V
Nambiar, P T C
Ausubel, F M
 
Subject Agriculture-Farming, Production, Technology, Economics
 
Description Random transposon TnS mutagenesis of Bradyrhizobium sp. (Arachis) strain NC92, a member of the cowpea cross-inoculation group, was carried out, and kanamycin-resistant transconjugants were tested for their symbiotic phenotype on three host plants: groundnut, siratro, and pigeonpea. Two nodulation (Nodphenotype) mutants were isolated. One is unable to nodulate all three hosts and appears to contain an insertion in one of the common nodulation genes (nodABCD); the other is a host-specific nodulation mutant that fails to nodulate pigeonpea, elicits uninvaded nodules on siratro, and elicits normal, nitrogen-fixing nodules on groundnut. In addition, nine mutants defective in nitrogen fixation (Fix- phenotype) were isolated. Three fail to supply symbiotically fixed nitrogen to all three host plants. Surprisingly, nodules elicited by one of these mutants exhibit high levels of acetylene reduction activity, demonstrating the presence of the enzyme nitrogenase. Three more mutants have partially effective phenotypes (Fix') in symbiosis with all three host plants. The remaining three mutants fail to supply fixed nitrogen to one of the host plants tested while remaining partially or fully effective on the other two hosts; two of these mutants are Fix- in pigeonpea and Fix' on groundnut and on siratro, whereas the other one is Fix- on groundnut but Fix' on siratro and on pigeonpea. These latter mutants also retain significant nodule acetylene reduction activity, even in the ineffective symbioses. Such bacterial host-specific fixation (Hsf) mutants have not previously been reported Fix' on groundnut and on siratro, whereas the other one is Fix- on groundnut but Fix' on siratro and on pigeonpea. These latter mutants also retain significant nodule acetylene reduction activity, even in the ineffective symbioses. Such bacterial host-specific fixation (Hsf) mutants have not previously been reported.
 
Publisher American Society for Microbiology
 
Date 1987
 
Type Article
PeerReviewed
 
Format application/pdf
 
Language en
 
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Identifier http://oar.icrisat.org/1435/1/Journal_of_Bacteriology_169%285%29_2177-2186_1987.pdf
Wilson, K J and Anjaiah, V and Nambiar, P T C and Ausubel, F M (1987) Isolation and characterization of symbiotic mutants of bradyrhizobium sp. (arachis) strain NC92: mutants with host-specific defects in nodulation and nitrogen fixation. Journal of Bacteriology, 169 (5). pp. 2177-2186.