Molecular Relatedness Among Cryptic Plasmids inPseudomonas syringaepv.glycinea

Abstract

Molecular homology was detected among the plasmids harbored by 6 pathogenic strains of P. syringae pathovar glycinea. By using the Southern blot technique, radioactive plasmid DNA probe prepared from strain LR 100 hybridized to 55-75% of the EcoRI-generated fragments of the other 5 strains. The reciprocal reaction was performed between membrane-bound EcoRI-digested LR100 plasmid DNA and plasmid probe prepared from 4 of the other strains. Each of these probes hybridized to 3 specific EcoRI fragments from plasmid pMC11 and 1 fragment from plasmid pMC10. From 1-9 other bands showed homology with specific probes. This interrelationship among the plasmids was not detected by visual examination of the EcoRI fingerprints, although similarities between the restriction patterns of some plasmids were clearly evident.