Antifungal properties of chitinases from Castanea sativa against hypovirulent and virulent strains of the chestnut blight fungus Cryphonectria parasitica

Four proteins (C1, C2, C3 and C4) with a chitin binding domain have been pu rified from European chestnut (Castanea sativa Mill.) plantlets grown in vi tro. Three of the proteins C2, C3 and C4 have chitinase activity. C3 from i ts N-terminal sequence is a Class I basic chitinase with high sequence homo logy with other Class I chitinases from chestnut cotyledons and other plant s. Antifungal tests showed that C1, C3 and C4 inhibit hyphal growth of the chestnut blight fungus Cryphonectria parasitica in culture. The proteins we re much more effective in inhibiting the hypovirulent form of the fungus th an the virulent form, suggesting that the Hypovirus induced effect on virul ence may be due to changes in the susceptibility of C. parasitica to host d efense responses. (C) 1999 Academic Press.