THE PHYTOPATHOGENIC FUNGUS CLADOSPORIUM-FULVUM IS NOT SENSITIVE TO THE CHITINASE AND BETA-1,3-GLUCANASE DEFENSE PROTEINS OF ITS HOST, TOMATO

Inoculation of tomato (Lycopersicon esculentum) with an avirulent race of Cladosporium fulvum results in a substantial increase in extra- and intracellular chitinases and beta-1,3-glucanases in the host. In this communication we describe the purification of a 27 kDa, extracellular chitinase [isoelectric point (pI) < 4.8] and two intracellular chitinases (30 and 32 kDa, pI 9.1 and pI > 10, respectively), from C. fulvum-infected tomato leaves. Assessment of the antifungal activity of crude protein preparations from such leaves, containing a complete set of the extra- and intracellular tomato chitinases and beta-1,3-glucanases, by in vitro bioassays, revealed that the Lest Fungus Trichoderma viride is highly sensitive to the hydrolytic enzymes. The antifungal activity was found to reside in the basic, intracellular isoforms of the chitinases and beta-1,S-glucanases. The acidic, extracellular enzymes did not show any antifungal activity. Germinated conidia of C.fulvum were not inhibited by crude preparations of chitinase and beta-1,3-glucanase; even at high concentrations these preparations showed no antifungal activity against C.fulvum. The apparent insensitivity of C. fulvum to tomato chitinases and beta-1,S-glucanases in in vitro bioassays and the role of these enzymes in resistance of tomato against C. fulvum, are discussed.