OCCURRENCE OF MULTIPLE FORMS OF ELICITINS IN PHYTOPHTHORA-CRYPTOGEA

The phytopathogenic fungus Phytophthora cryptogea produces large amoun ts of cryptogein, a proteinaceous elicitor of active defences in tobac co, which induces a hypersensitive-like response and acquired resistan ce to the compatible pathogen Phytophthora parasitica var. nicotinae. We found that P. cryptogea actually synthesizes at least three isoform s of cryptogein, differing by their pI. These three isoforms were puri fied and were tested on tobacco. The major form is a basic protein, cr yptogein B, which was identified to the previously described cryptogei n. The two other forms, A1 and A2, are acidic and resemble other acidi c elicitins already characterized, by their behaviour in electrophores is, their amino-acid sequence and by their ability to induce resistanc e in tobacco plants with limited or no phytotoxic symptoms.