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Physiology and Biochemistry

Isolation From Three Species of Colletotrichum of Glucan-Containing Polysaccharides That Elicit Browning and Phytoalexin Production in Bean. Anne J. Anderson, Assistant Professor of Plant Pathology, Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331; Phytopathology 68:189-194. Accepted for publication 14 June 1977. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-189.

Glucan-containing polysaccharides from three species of Colletotrichum initiate symptoms of a defense response (browning and phytoalexin production) in bean, Phaseolus vulgaris. Two species, C. trifoli and C. destructivum, were not pathogenic on bean whereas the third, C. lindemuthianum, was a bean pathogen. The polysaccharides were obtained from culture filtrates and were not adsorbed by anion and cation exchange resins. Gel filtration on Agarose 5 M showed that each Colletotrichum sp. produced a high-molecular-weight fraction rich in glucan that initiated the symptoms when less than 10^–7 g of glucose equivalents was applied to bean cotyledons. Lower-molecular-weight fractions from each species were active on bean. These fractions contained glucose, mannose, and galactose; those from C. trifoli and C. destructivum also contained rhamnose.