Elicitin 172 from an isolate of Phytophthora nicotianae pathogenic to tomato

Elicitin 172, an acid protein with elicitor activity, has been isolated in true form from culture filtrates of Phytophthora nicotianae, the causal agent of crown and root rot of tomato (Lycopersicon esculentum). The M(r) (10,349 +/- 1) of the purified protein, determined by ES-MS, is identical to that calculated for parasiticein using the mean isotopic composition and assuming the occurrence of three disulfide bridges. The primary structure of elicitin 172, determined using also MALDI-MS experiments, shows complete identity with parasiticein, with elicitin 310 and a cloned elicitin gene from P. parasitica (= P. nicotianae), confirming conservation of the elicitin sequence within a single species. The protein induces necrosis (hypersensitive reaction) on tobacco, but no symptoms on tomato, when applied on the leaves. Tomato pretreated with elicitin 172 was affected by P. nicotianae, as well as by the phytotoxic aggregates, naturally occurring with the elicitin in the non permeated dialysis fraction of culture filtrates. Finally, the elicitin induce protection of capsicum (Capsicum annuum) and vegetable marrow (Cucurbita pepo) from P. capsici.