MOLECULAR CHARACTERIZATION OF FIELD ISOLATES OF PSEUDOMONAS-SYRINGAE PV GLYCINEA DIFFERING IN CORONATINE PRODUCTION

Coronatine-producing and non-producing strains of Pseudomonas syringae pv. glycinea have been examined. We found a connection between copper resistance and synthesis of coronatine. Published data implied that t hese properties may be encoded on different plasmids. Production of co ronatine and copper resistance were also found to be correlated for pv . glycinea in 19 field-isolates from leaf spots of plants in a soybean field and in 28 strains of a bacterial culture collection. Genomic di versity within pv. glycinea was investigated by plasmid profiling, DNA hybridization studies and PCR analysis. All strains unable to produce coronatine (cor-) were sensitive to copper ions and showed no homolog y to DNA from plasmid pSAY1, which carries a gene cluster for steps in coronatine production. In addition, cor- strains could be distinguish ed from coronatine-producing strains by a single unique band when ampl ified by random primer PCR. Plasmid profiles of strains isolated from field-populations during 1983, 1985 and 1990 showed that coronatine-pr oducing and non-producing strains were present. The plasmid patterns a lso varied in 28 strains examined from a culture collection. No correl ation between plasmid patterns and race specificity was observed. Cosm id pSAY1 proved to be an effective probe for detection of the coronati ne synthesis genes and also revealed polymorphisms in coronatine produ cing strains of pv. glycinea.