Once a pathogen, always a pathogen? Not so—the fungus Pseudozyma flocculosa provides an intriguing example of a pathogen that took a different route (reviewed in Bélanger et al., 2012). Initially isolated from a powdery-mildew–infected leaf, P. flocculosa acts as a strong antagonist of powdery mildews (Erysiphales) and was thus developed as a biocontrol agent. However, the mechanism by which it...
