Evidence for a primary role of active oxygen species in induction of host cell death during infection of bean leaves with Botrytis cinerea.

摘要

Experiments were conducted to find direct evidence for the involvement of active oxygen species (AOS) in the initiation of infection by B. cinerea. Leaf discs of bean (Phaseolus vulgaris) genotypes 1 (N 90598), 2 (N 90563 Huron), 12 (1642114/I) and14 (416664/S) were inoculated with isolates of B. cinerea of varying virulence. A hydrogen peroxide assay was used to detect H2O2 in the incubation medium and in infected leaf discs. The effects of scavengers on infection were also tested in leaf disc inoculation experiments. In situ generated OH radicals were detected by an assay based on oxidative degradation of 2-deoxyribose. Peaks of H2O2 within 48 h and of OH radicals within 24 h of inoculation were positively associated with the aggressiveness ofB. cinerea isolates. B. cinerea isolates, particularly aggressive isolates, suppressed plant peroxidase activity. H2O2 accumulated more rapidly in infected leaf discs than in the incubation medium. AOS scavengers reduced the severity of infection by B. cinerea. It is concluded that the toxic effects of elevated levels of H2O2 and OH radicals during early stages of infection induce host cell death. A possible role for AOS in plant resistance is suggested.