Phenotypic Diversity in Strains of Pseudomonas solanacearum Isolated from a Single Potato Field in Northeastern Florida. R. J. McLaughlin, Graduate Research Assistant, Department of Plant Pathology, University of Wisconsin, Madison 53706. L. Sequeira, Professor, Department of Plant Pathology, University of Wisconsin, Madison 53706. Plant Dis. 73:960-964. Accepted for publication 26 June 1989. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1989. DOI: 10.1094/PD-73-0960.

Eighty-five strains of Pseudomonas solanacearum isolated from diseased tubers and soil samples from a 0.3-ha field near Hastings, Florida, were heterogeneous for antibiotic production and sensitivity, pathogenicity, and carbohydrate utilization. Major variation was noted in antibiotic production and strain aggressiveness. All strains belonged to race 1, biovar 1. Eight strains belonged to one of three groups: 1) weakly aggressive to potato cultivars Atlantic (susceptible) and Ontario (moderately resistant), 2) highly aggressive to both potato cultivars, and 3) highly aggressive to Atlantic but weakly pathogenic toward Ontario. All strains were aggressive pathogens to the tomato cultivar Rutgers and the eggplant cultivar Black Beauty. Although the Florida strains belonged to biovar 1, they differed in ability to oxidize galactose, arabinose, and lactose. All strains elicited the hypersensitive response in leaves of the tobacco cultivar Bottom Special. When the 85 strains were tested for antibiotic production against 26 indicator strains, there were 23 phenotypes for antibiotic production and 12 for antibiotic sensitivity. Forty-six of the strains belonged to four groups that differed in ability to produce antibiotics against three of the indicator strains. Differences in antibiotic production and sensitivity were also evident among 13 strains tested against 10 exotic strains of P. solanacearum.

Keyword(s): bacteriocins, potato brown rot.