Nucleic Acid Homologies in the Genus Pseudomonas

On the basis of ribosomal ribonucleic acid homologies, the genus Pseudomonas can be divided into at least five distinct groups, some of which are as distantly related to each other as they are to Escherichia coli. One of these groups contains members of the genus Xanthomonas. The data presented support and extend the previous grouping based on deoxyribonucleic acid homologies and support the current view that the portion of the genome coding for ribosomal ribonucleic acid is more conserved in the course of evolution than the bulk of the genome.