Abstract:

To explore the composition and structure of Arthrinium phaeospermum toxins which cause wilt of the tender leaves and twigs of a hybrid bamboo (Bambusa pervariabilis×Dendrocalamopsis grandis), the crude toxic proteins were extracted from the bacterium by liquid culture, ammonium sulfate precipitation and polyethylene glycol concentration. One composition (P₃) with pathogenic activity was obtained by Sephadex G-100 gel chromatography and Q sepharose fast flow anion exchange resin. The sequencing result of P₃ showed that the 7-ammonia-acids sequence at the N-terminal end was H₂N-Ala-Gln-Ser-Val-Pro-Tyr-Gly, which had high homology with the precursor of subtilisin protease from Bacillus subtilis by the homophyly retrieval in NCBI. The molecular weight of P₃ (27 kD) was very close to that of subtilisin protease. The pathogenicity experiment of P₃ indicated that it could cause the same typical symptom as that of the pathogen, but the reaction was quicker than that of the pathogen itself. The effectively originative concentration was 5-10 μg·mL^-1, and the higher the concentration, the stronger the pathogenicity.

Key words: Arthrinium phaeospermum, toxin, protein, pathogenic activity, Bambusa pervariabilis×, Dendrocalamopsis grandis