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Physiology and Biochemistry

The Multi-Component Extracellular Polysaccharide of Clavibacter michiganense subsp. insidiosum. Neal K. Van Alfen, Department of Biology, Utah State University, Logan 84322-4500; Brent D. McMillan, and Paul Dryden. Department of Biology, Utah State University, Logan 84322-4500. Phytopathology 77:496-501. Accepted for publication 12 September 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-496.

Extracellular polysaccharides (EPS) of many plant pathogenic bacteria are considered to be important virulence factors. A role in virulence expression for the EPS of Clavibacter (Corynebacterium) michiganense subsp. insidiosum has been proposed, but relatively little is known of the nature of this EPS beyond its basic repeating unit. We report here that the EPS of this pathogen consists of three different components, one EPS (component I) is an aggregate of another, 5 MDa EPS (component II). At least nine polypeptides are also associated with the component I aggregate. Component III (22 kDa) is different from the other two in its sugar composition and varies among strains and cultures from different media.

Additional keywords: bacterial wilt of alfalfa, Medicago sativa.