VIEW ARTICLE

Physiology and Biochemistry

Properties of the Extracellular Polysaccharides of Clavibacter michiganense subsp. insidiosum That May Affect Pathogenesis. Neal K. Van Alfen, Department of Biology, Utah State University, Logan 84322-4500; Brent D. McMillan, and Yeelan Wang. Department of Biology, Utah State University, Logan 84322-4500. Phytopathology 77:501-505. Accepted for publication 12 September 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-501.

The extracellular polysaccharide (EPS) of Clavibacter (Corynebacterium) michiganense subsp. insidiosum consists of three different sized components. Each of these EPS components reduced transpiration of alfalfa cuttings when introduced into the cut stem. The largest component accumulated in stems of cuttings and was unable to pass through leaf traces. This EPS component was too large to pass through pit membranes of alfalfa stems. The 5 MDa component likewise was unable to pass through leaf traces but is of a size that could allow it to pass through pit membranes of alfalfa stems. The smallest EPS component (22 kDa) passes freely through pit membranes and accumulates in leaves. EPS production was found to be regulated rather than constitutive, being produced primarily during stationary phase of growth. This implies that it may not be important in the initial events of host-pathogen interactions.