Endophytic Expression of nif Genes of Azoarcus sp. Strain BH72 in Rice Roots

Transcriptional fusions of gusA and gfp to the nifH gene as well as immunogold labeling with antibodies against the iron protein of nitrogenase revealed high nitrogenase gene expression levels of the endophyte Azoarcus sp. strain BH72 inside infected rice roots (Oryza sativa) in the laboratory. Thus, environmental conditions inside rice roots are permissive for endophytic nitrogen fixation in bacterial microcolonies in the aerenchyma.