Neighbor-joining (Saitou and Nei 1987) phylogenetic tree calculated with ClustalX 1.83 (Thompson et al. 1997) from 16S rRNA gene sequences. Distances were corrected for multiple substitutions (Kimura 1980); otherwise, default settings were used. Numbers give bootstrap support values from 1000 bootstrapped samples. The outgroup used is Streptomyces coelicolor (NC003888). Accession numbers for the organisms are given after the name and species number as given in Normand and Fernandez (2007). In the case of the unisolated cluster 2 frankiae, the host plant genus from which 16S rRNA gene sequences were amplified is given. Distances in the bar are in substitutions/site.