Involvement of nifA and glnB genes in expression of nitrogen fixation genes in Azospirillum brasilense
Résumé
Using promoter fusions to lacZ as reporter gene, regulation of nif gene expression was studied in Azospirillum brasilense Sp7, in free-living state and during association of Azospirillum brasilense with wheat. In both conditions, nif gene expression requires NifA and the glnB product. The same protocol was successfully used to show that auxotrophic mutants (glnA, trpC, trpD) were impaired in the colonisation efficiency as compared to the wild type, whereas a nifA-Tn5 mutant was not.