Phylogenetic placement of uncultured Ceanothus microsymbionts using 16S rRNA gene sequences

Full-length 16S rDNA sequences were amplified directly from the nodules of Ceanothus americanus L. and Ceanothus thyrsiflorus Eschsch, using the polymerase chain reaction. Sequences were determined using an automated sequencer, compared against those in GenBank, and assembled into consensus sequences. The sequences were aligned with other full-length Frankia 16S rDNA sequences available from the data base. Phylogenetic trees were obtained using three different algorithms: neighbor joining, parsimony, and the maximum-likelihood method. All three methods showed that these Ceanothus L. microsymbionts were most closely related to the microsymbiont associated with Dryas drummondii Richardson ex Hook. Lvs, rather than Frankia isolated from the Elaeagnaceae.