Hydroxyl radical scavengers inhibit lateral-type sclerotial differentiation and growth in phytopathogenic fungi

The effect of certain hydroxyl radical scavengers (dimethyl sulfoxide, p-ni trosodimethylaniline, ethanol, benzoate, salicylate and thiourea) was studi ed on lateral sclerotial differentiation and growth of Sclerotium rolfsii a nd Sclerotinia minor. At low growth noninhibiting scavenger concentrations there was a scavenger dose- and reaction rate-correlation with increased sc lerotial differentiation delay and inhibition. Higher scavenger concentrati ons further inhibited sclerotial differentiation and finally arrested growt h, providing antioxidant antifungal alternatives to traditional fungicides. Salicylate and p-nitrosodimethylaniline (with the highest hydroxyl radical reaction rates) were the most effective inhibitors of sclerotial different iation and growth. These data strongly support our theory which suggests th at oxygen free radicals are responsible for sclerotial differentiation in f ungi.