Abstract
N-(3', 5'-dichlorophenyl)-1, 2-dimethylcyclo propane-1, 2-dicarboximide, S-7131 (Sumilex®), inhibited remarkably the mycelial growth and conidial germination of Botrytis cinerea in a liquid nutrient medium, causing unusual swelling of hyphae and shortening of their internodes at its sublethal concentrations, and bursting cells at the lethal concentrations. Bursting of cells which was observed 2 to 3hr after the treatment of the fungicide was the earliest morphological response. This was observed on growing cells but not on resting cells. The hyphal cells treated with S-7131 burst similarly under high osmotic pressure. In the presence of S-7131, protoplasts obtained from the hyphae of B. cinerea were stable and regeneratedcell wall-like structures, which were observed under a phase-contrast microscope after osmotic shock. The results suggest that S-7131 neither affects the cell wall and the cell membrane by its direct action norinhibits the synthesis of the cell wall. S-7131 probably causes bursting of cells as an indirect effect.
