1999 Volume 65 Issue 6 Pages 629-634
Production of the phytotoxin coronatine was investigated among Pseudomonas syringae pathovars using 55 bacterial strains including 46 pathotype strains. To detect production of coronatine, a bioassay was performed using potato tuber. The presence of the cfl gene, one of the coronatine-production genes, was also detected by PCR. As a result, we found new producers of coronatine in six pathotype strains of six pathovars of P. syringae pv. aesculi, pv. berberidis, pv. cannabina, pv. coronafaciens, pv. ulmi and pv. zizaniae in addition to five pathovars of pv. atropurpurea, pv. glycinea, pv. maculicola, pv. morsprunorum and pv. tomato which had been previously reported as producers. One of these bacteria, P, syringae pv. coronafaciens is known to be a tabtoxin producer. In the pathotype strain, however, the PCR product of a portion of tabA, which is one of the tabtoxin production genes, was not detected, in spite of the detection of that PCR product in seven other strains of the same pathovar. Furthermore, the pathotype strain did not form lesions on oats in a way similar to that mentioned in the original description, while the other seven strains did. Because the pathotype strain (MAFF 302257=ICMP 3113) does not exhibit generally recognized characteristics of the pathovar for pathogenicity and toxin production, strain MAFF 302257 (=ICMP 3113) is not suitable as the pathotype.