Suppression of the oxidative burst as pathogenicity factor of Botrytis cinerea (abstract only)

Citation:Unger C., Kleta S., von Tiedemann A. (2002): Suppression of the oxidative burst as pathogenicity factor of Botrytis cinerea (abstract only). Plant Protect. Sci., 38: 240-240.
The oxidative burst is initiated by a strong increase of superoxide radicals. Superoxide radicals are thought to trigger the hypersensitive response as prerequisite of plant defence. So far, these mechanisms are described for an interaction of plants with avirulent phytopathogenic bacteria and biotrophic fungi, which have to suppress the plant oxidative burst as prerequisite for a successful infection. On bean leaf discs inoculation with different isolates of B. cinerea leads to 5 different symptoms, indicating different pathotypes. Two pathotypes are aggressive indicated by growing lesions, whereas non-aggressive isolates initiate dark brown spots, indicating a hypersensitive-like response. In bean suspension cells generation of superoxide was found to be below the control level after inoculation with aggressive isolates. Inoculation with the non-aggressive types initiates a very strong increase of superoxide radicals. In aggressive isolates the burst suppression was associated with a decrease in peroxidase activity. On non-inoculated bean leaf discs small amounts of superoxide radicals were produced and visualized by NBT-staining. After inoculation with aggressive isolates the production of superoxide was suppressed in a 2–3 mm zone around the growing lesions. A transfer of intercellular fluid from this zone also led to an inhibition of the superoxide production without killing the tissue. The same phenomenon was observed after transfer of suspension cell culture filtrate inoculated with aggressive isolates B. cinerea about 30 hpi.

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