Antifungal properties of lectin and new chitinases from potato tubers.

We have purified from potato tubers, the lectin STA devoid of chitinase activity and two chitinases devoid of lectin activity. Both enzymes are 16 kDa glycoproteins, and probably belong to a new family of plant chitinases. The respective antifungal properties of lectin and chitinases were studied by following their effects against early developmental stages of Fusarium oxysporum, a fungal potato pathogen. Here we demonstrate that: (1) lectin does not inhibit mycelial growth but irreversibly inhibits conidia germination and alters the germ tubes; and (2) chitinases block mycelial growth as well as conidia germination and lyse germ tubes.