ANALYSIS OF THE PHYLOGENETIC-RELATIONSHIPS OF STRAINS OF BURKHOLDERIA-SOLANACEARUM, PSEUDOMONAS-SYZYGII, AND THE BLOOD-DISEASE BACTERIUM OFBANANA BASED ON 16S RIBOSOMAL-RNA GENE-SEQUENCES

We determined nearly complete 16S rRNA gene sequences for 19 isolates of Burkholderia solanacearum, three isolates of the blood disease bact erium of bananas, and two isolates of Pseudomonas syzygii, the cause o f Sumatra disease of cloves, The dendrogram produced by comparing all of these sequences revealed that there were two divisions, which corre sponded to the results obtained previously in a restriction fragment l ength polymorphism analysis (D, Cook, E, Barlow, and L, Sequeira, Mel. Plant Microbe Interact, 2:113-121, 1989) and a total 16S ribosomal DN A (rDNA) sequence analysis of four isolates representing four biovars of B, solanacearum (X. Li, M. Dorsch, T. Del Dot, L. I, Sly, E, Stacke brandt, and A, C, Hayward, J, Appl, Bacteriol, 74:324-329, 1993), Divi sion 1 comprised biovars 3, 4, and 5 and an aberrant biovar 2 isolate (strain ACH0732), and division 2 included biovars 1, 2, and N2, the bl ood disease bacterium, and P, syzygii. Specific nucleotides at positio ns 458 to 460 (UUC) and 474 (A) characterized division 2, whereas in d ivision 1 the nucleotides at these positions were ACU and U, respectiv ely, However, strain ACH0732 had a U at position 458, as did division 2 isolates, and G instead of U at position 474, Division 2 consisted o f two subdivisions; one subdivision contained two B, solanacearum isol ates that originated from Indonesia, P. syzygii strains, and blood dis ease bacterium strains, and the other subdivision contained all of the other division 2 isolates. Within division 1, the level of 16S rDNA s equence similarity ranged from 99.8 to 100%, and within division 2, th e levels of 16S rDNA sequence similarity ranged from 99.1 to 100%. The division 1 isolates exhibited an average level of 16S rDNA sequence s imilarity to division 2 isolates of 99.3% (range, 99.1 to 99.5%), The occurrence of consistent polymorphisms in the 16S rDNA sequences of B, solanacearum strains, in particular unique 16S rDNA sequence differen ces in aberrant biovar 2 isolate ACH0732, and the occurrence of the In donesian subdivision of division 2 suggest that this group is a rapidl y evolving (tachytelic) group.