An ELISA Test for Bacterial Ring Rot of Potato with a New Monoclonal Antibody. S. H. De Boer, Agriculture Canada, Vancouver Research Station, 6660 NW Marine Drive, Vancouver, BC, Canada, V6T 1X2. A. Wieczorek, and A. Kummer. Agriculture Canada, Vancouver Research Station, 6660 NW Marine Drive, Vancouver, BC, Canada, V6T 1X2. Plant Dis. 72:874-878. Accepted for publication 2 June 1988. Copyright 1988 Department of Agriculture, Government of Canada. DOI: 10.1094/PD-72-0874.

A monoclonal antibody was produced to an extracellular soluble fraction of a culture of Corynebacterium sepedonicum and used in several serological testing procedures. The antibody reacted with C. sepedonicum antigen in enzyme-linked immunosorbent assay (ELISA), immunodiffusion, and latex agglutination, but not in immunofluorescence tests. In ELISA, it reacted with all strains of C. sepedonicum tested, but not with any other plant pathogenic corynebacteria. However, it did cross-react with one of 12 unidentified bacteria that had been previously selected from among many strains isolated from potato on the basis of serological cross-reaction with C. sepedonicum polyclonal antiserum. The ELISA test applied to potato tubers was highly sensitive, giving positive reactions at greater than 10^-6 dilution of tissue extracts from ring rot-infected tubers. Furthermore, apparent contamination of healthy tubers from an external source was detected.