Production of Plant Cell Wall Degrading Enzymes byPhoma medicaginisf. sp.pinodella

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Abstract
Infection of Austrian winter peas (Pisum sativum var. arvense) by Phoma medicaginis f. sp. pinodella resulted in necrosis and stem girdling. Extracts prepared from diseased pea stems contained enzymes that degraded xylan, CM-cellulose, pectin, galactan and arabinogalactan, as well as exoglycosidases specific for hydrolysis of .alpha.-linked galactose and .beta.-linked xylose and glucose. Extracts of healthy stem tissues contained lower levels, if any, of these enzymes. During culture of P. medicaginis f. sp. pinodella on isolated pea leaf and stem cell walls, enzymes similar to those detected in diseased pea tissues were secreted sequentially. Identical patterns of enzyme production were obtained with cultures grown on cell walls isolated from young or old stems. In contrast, inoculation studies with the fungus showed colonization of young stems only.