SPECIFIC 16S RIBOSOMAL-RNA-TARGETED OLIGONUCLEOTIDE PROBE AGAINST CLAVIBACTER-MICHIGANENSIS SUBSP SEPEDONICUS

In this article we report on the polymerase chain reaction amplificati on of a partial 16S rRNA gene from the plant pathogenic bacterium Clav ibacter michiganensis subsp. sepedonicus. A partial sequence (about 40 0 base pairs) of the e;ene was determined that covered two variable re gions important for oligonucleotide probe development. A specific 24me r oligonucleotide probe targeted against the V6 region of 16S rRNA was designed. Specificity of the probe was determined using dot blot hybr idization. Under stringent conditions (60 degrees C), the probe hybrid ized with all 16 Cl. michiganensis subsp. sepedonicus strains tested. Hybridization did not occur with 32 plant pathogenic and saprophytic b acteria used as controls under the same conditions. Under less stringe nt conditions (55 degrees C) the related Clavibacter michiganensis sub sp. insidiosus, Clavibacter michiganensis subsp. nebraskensis, and Cla vibacter michiganensis subsp. tesselarius also showed hybridization. A t even lower stringency (40 degrees C), all Cl. michiganensis subspeci es tested including Clavibacter michiganensis subsp. michiganensis sho wed hybridization signal, suggesting that under these conditions the p robe may be used as a species-specific probe for Cl. michiganensis.