Proteinase, Chitinase, and Chitosanase Activities in Germinating Spores of Piptocephalis virginiana

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Abstract
Optimum conditions for germination of axenic spores of the biotrophic mycoparasite, Piptocephalis virginiana were determined. Beside the addition of host extract into nutrient broth, shake cultures promoted considerably better germination than still cultures. Germinating spores of the mycoparasite produced intracellular proteinases capable of hydrolysing casein and haemoglobin at acidic, weakly acidic, and neutral pH. Amendment of nutrient broth with isolated host cell walls showed no increase in intracellular proteinase activity. Haemoglobin hydrolysis by intracellular proteinases was inhibited by phenylmethane sulfonyl fluoride (PMSF), di-isopropyl fluoro phosphate (DEP) and mercuric chloride, whereas caseinolysis was inhibited by N-.alpha.-p-tosyl-L-lysine chloromethylketone (TLCK) and mercuric chloride at pH 10. Enzyme extract from germinating spores also showed chitinase and chitosanase activities which were stimulated by the presence of isolated host cell walls in the nutrient medium. The possible role of these hydrolytic enzymes in biotrophic mycoparasitism is discussed.