Early detection of Phoma lingam infection in oilseed winter rape Before visible symptoms appear

A chlorophyll fluorescence technique enabled early detection of disturbances in the activity of the photosynthet- ic apparatus under Phoma lingam infection. The photosynthetic apparatus of leaves and cotyledons exhibited a negative response to P. lingam inoculation. The effect disappeared more rapidly in leaves, which were not inoc- ulated directly, than in cotyledons, which were inoculated directly. Photosynthetic apparatus disturbances were detected in cotyledons and leaves as early as 24 h after inoculation. Photosynthetic apparatus activity can be affected by the level of hydrogen peroxide, which in cotyledons probably was an element of the hypersensitive response and in leaves could induce an increase in pathogenesis-related proteins, chitinase and β -1,3-glucanase.