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 purified from European chestnut (Castanea sativa Mill.) plantlets grown in vitro. Three of the proteins C2, C3 and C4 have chitinase activity. C3 from its N-terminal sequence is a Class I basic chitinase with high sequence homology with other Class I chitinases from chestnut cotyledons and other plants. Antifungal tests showed that C1, C3 and C4 inhibit hyphal growth of the chestnut blight fungus Cryphonectria parasitica in culture. The proteins were much more effective in inhibiting the hypovirulent form of the fungus than the virulent form, suggesting that the Hypovirus induced effect on virulence may be due to changes in the susceptibility of C. parasitica to host defense responses. (C) 1999 Academic Press.