Identification and phylogenetic analysis of Burkholderia cepacia complex bacteria isolated from rot of onion bulbs in Tohoku region of Japan

Abstract

Burkholderia cepacia complex (Bcc) bacterial isolates from onion bulbs with rot in the Tohoku region of Japan were identified using a pathogenicity test, phenotypic characterization, restriction fragment length polymorphism (RFLP) analysis, and phylogenetic analyses based on 16S rRNA and housekeeping genes. Onion isolates caused a rot on onion bulbs similar to the field rot. Phenotypic properties of onion isolates were consistent with those of Bcc strains reported previously. The RFLP analysis using recA gene PCR amplicon from the onion isolates showed five distinct banding patterns. On the basis of phylogenetic analyses using 16S rRNA gene and housekeeping genes gyrB, rpoD, and recA, onion isolates were identified as B. cepacia, B. cenocepacia, B. ambifaria, and B. pyrrocinia, members of Bcc. In the phylogenetic tree constructed using the housekeeping gene sequences, onion isolates and reference strains producing a purple nondiffusible pigment formed a group in the B. cepacia branch. B. ambifaria and B. pyrrocinia caused rot symptoms on onion the same as those caused by B. cepacia and B. cenocepacia strains.