The Effect of Benomyl on the Fine Structure of Botrytis fabae

SUMMARY: Conidia of Botrytis fabae germinate in the presence of sublethal concentrations of benomyl to produce swollen and distorted germ tubes which branch more frequently than those of normal conidia. Multiple germ-tube emergence also occurs to a greater extent in treated conidia. The orientation of organelles towards the hyphal tip is disorganized in benomyl-treated germ tubes. Endoplasmic reticulum which occurs as multiple strands surrounding the nuclei in normal germinating spores is broken up into a fragmented network. Part of the endoplasmic reticulum occurs as strands and vesicles close to the plasmalemma, a configuration which corresponds closely to the situation in resting conidia. The findings inchemically fixed sections are confirmed by the appearance of freeze-etched replicas. Benomyl treatment seems to stimulate lomasome formation, and freeze-etched treated nuclei appear deeply lobed and convoluted.