Ribosomal Ribonucleic Acid Cistron Similarities of Phytopathogenic Pseudomonas Species

Deoxyribonucleic acid (DNA)-ribosomal ribonucleic acid (rRNA) hybridizations were carried out between 23S 14C- or 3H-labeled rRNAs from type strains Pseudomonas fluorescens ATCC 13525, Pseudomonas acidovorans ATCC 15668, Pseudomonas solanacearum ATCC 11696, and Xanthomonas campestris NCPPB 528 and DNA from one or more strains of several taxonomically assigned or unassigned phytopathogenic Pseudomonas species. The strains were assigned to one of the following rRNA branches: (i) the P. fluorescens rRNA branch (the authentic pseudomonads), containing also Pseudomonas agarici, Pseudomonas amygdali, Pseudomonas asplenii, Pseudomonas caricapapayae, Pseudomonas cichorii, Pseudomonas corrugata, Pseudomonas fuscovaginae, Pseudomonas marginalis (P. marginalis pathovar marginalis, P. marginalis pathovar alfalfae, and P. marginalis pathovar pastinacae), Pseudomonas meliae, the Pseudomonas syringae group (including “Pseudomonas aceris,” “Pseudomonas antirrhini,” “Pseudomonas apii,” “Pseudomonas berberidis,” “Pseudomonas cannabina,” “Pseudomonas coronafaciens”, “Pseudomonas eriobotryae,” “Pseudomonas lapsa,” “Pseudomonas maculicela” “Pseudomonas oryzicola,” “Pseudomonas panici,” “Pseudomonas passfflorae,” “Pseudomonas primulae,” “Pseudomonas ribicola,” “Pseudomonas sesami,” “Pseudomonas striafaciens,” P. syringae, “Pseudomonas ulmi,” and “Pseudomonas viburni”), Pseudomonas tolaasii, Pseudomonas viridiflava, and “Pseudomonas washingtoniae;” (ii) the P. solanacearum rRNA branch, containing P. solanacearum, Pseudomonas andropogonis (synonym, “Pseudomonas stizolobii”), Pseudomonas caryophylli, Pseudomonas cepacia, Pseudomonas gladioli (synonyms, “Pseudomonas alliicola” and “Pseudomonas marginata”), Pseudomonas glumae, Pseudomonas rubrisubalbicans, and Pseudomonas woodsii; (iii) the P. acidovorans rRNA branch, containing also “Pseudomonas alboprecipitans” (synonym of Pseudomonas avenae), Pseudomonas pseudoalcaligenes subsp. citrulli, Pseudomonas rubrilineans, and “Pseudomonas setariae;” and (iv) the Xanthomonas rRNA branch, containing X. campestris, Pseudomonas betle, “Pseudomonas gardneri,” Pseudomonas hibiscicola, “Pseudomonas mangiferaeindicae,” “Pseudomonas viticola,” and “Pseudomonas vitiswoodrowii.” Pseudomonas flectens and Pseudomonas cissicola definitely have to be removed from the genus Pseudomonas. Pseudomonas cattleyae, and “Pseudomonas viridilivida” are heterogeneous and require additional examination.