FIG. 3.

Comparison of nosZ (A) and 16S rRNA (B) phylogenies. Boxes 1 to 6 display examples of closely related species clustering together in the nosZ tree. Not all sequences of Azospirillum sp. cluster together in the nosZ tree. Neighbor-joining trees were constructed from nucleotide sequences of nosZ and 16S fragments with approximate lengths of 700 and 1,400 bp, respectively. The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (500 replicates) is shown next to the branches. Bootstrap supports below 50% are not shown. The bars represent estimated sequence dissimilarities of 5% (A) and 2% (B).