Antigenic anomaly in a naturally occurring nonfluidal strain ofCorynebacterium sepedonicum

A nonfluidal strain (SSNF50) ofCorynebacterium sepedonicum (=Clavibacter michiganense subsp.sepedonicum) was isolated from potato (Solanum tuberosum) stems from Idaho. A precipitin band common to other strains was not detected in Ouchterlony double diffusion (ODD) tests of SSNF50. SSNF50 was indistinguishable from fluidal strain SS20 ofC. sepedonicum with respect to latent period in eggplant or potato, reaction in latex agglutination and fluorescent antibody stain, and level of population in infected potato stems. Latent period of infection in potato from nonfluidal strain SSNF201, isolated in the laboratory from a culture of fluidal strain SS20, was longer than that of SS20 or SSNF50 despite similar pathogen population levels. A precipitin band common to ODD tests of SS20 and SSNF50 was not detected in tests of SSNF201. SSNF50 is the first nonfluidal strain ofC. sepedonicum to be isolated from potatoes.