PCR detection of Clavibacter michiganensis subsp sepedonicus-infected tuber samples in a plate capture assay

The speed and sensitivity of PCR-based assays allow shorter turnaround time s for the detection of pathogens for which culture and serological methods are difficult or unavailable. PCR was performed with primer sets Cms50 and Cms72, designed previously by Mills et at. (1997) through subtractive hybri dization to detect Clavibacter michiganensis subspecies sepedonicus (Cms). In bacterial suspensions, fewer than three cells/10 ul reaction were detect ed after PCR amplicons were hybridized with specific DIG-labeled DNA probes in an enzyme-linked oligonucleosorbent assay (ELOSA). In naturally infecte d tuber samples representing three cultivars of potato, the diagnostic sens itivity of PCR/ELOSA was 96%, while the specificity exceeded 99%. PCR/ELOSA detected Cms in infected tuber samples with equal sensitivity regardless o f colony morphology, potato cultivar, or primer sets.