In vitro regulation of chitinase and chitin synthase activity of two mucoraceous hosts of a mycoparasite

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Abstract
Effects of partially purified preparations of proteinases extracted from Choanephora cucurbitarum and Phascolomyces articulosus, susceptible and resistant hosts of Piptocephalis virginiana, respectively, were studied in vitro on the activities of chitinase and chitin synthase of the same hosts. Both chitinase and chitin synthase are membrane bound, zymogenic, and activated by partial proteolysis. Host proteinases of acid and neutral type stimulated chitinase activity, but only the acid proteinase stimulated chitin synthase activity of the two hosts. Neutral proteinase of C. cucurbitarum inhibited its chitin synthase, whereas that of Ph. articulosus increased its chitin synthase activity. Partially purified preparations of neutral proteinase from the mycoparasite, Piptocephalis virginiana, however, enhanced chitinase and suppressed chitin synthase activity of both the hosts alike. The role of host proteinases in regulating the activity of chitinase and chitin synthase of the two host species is suggested.