Production of a host-specific toxin by germinating spores ofAlternaria brassicicola☆

摘要: Abstract Spore suspensions ofAlternaria brassicicolapathogenic toBrassicaspp. were incubated on the surface ofBrassicaleaves. The spore germination fluid was collected and examined for biological activity. In a detached leaf assay, induced water-soaking symptoms followed by brown necrotic lesions onBrassicaleaves susceptible to pathogen but did not cause visible non-host leaves. When spores of non-pathogenic speciesAlternaria alternatawere combined with inoculated leaves, could invadeBrassicaleaves, just as did. These results indicate thatA. brassicicolaproduces host-specific toxin(s) releases it during Toxin activity retained an ultrafiltration membrane 5 kDa cut off. toxin purified ion exchange chromatography gel filtration HPLC. molecular weight estimated be 35 SDS-polyacrylamide electrophoresis. heat labile also lost after treatment proteinase K. Thus, named AB-toxin is probably protein, first described among many toxins produced byAlternariaspecies.