FIG 9.

The proposed model of fengycin BS155 action in M. grisea hyphal cells. Fengycin BS155 interacts with the fungal hyphal cell membrane and enters the intracellular space (step 1). Fengycin BS155 damages the plasma membranes and then induces dysfunction of organelles and a burst of ROS (step 2). Fengycin BS155 reduces the MMP and downregulates the activities of ROS-scavenging enzymes (such as CAT and SOD), which in turn facilitates the production of additional ROS (step 3). Fengycin BS155 also induces DNA condensation, leading to the upregulation of DNA repair protein expression (step 4). Fengycin BS155 causes PARP cleavage (step 5), which is an important representative clue for hyphal cell apoptosis. Altogether, the organelle dysfunction, accumulation of ROS, and chromatin condensation induced by fengycin BS155 finally lead to cell death.