Natural Inhibitors of Fungal Polygalacturonases in Infected Fruit Tissues

Abstract

Isoelectric focusing of extracts of plum and peach tissue infected with Monilinia spp. revealed the presence of polygalacturonase even though little or no activity was detectable in crude extracts prior to fractionation. Mixing experiments confirmed the presence of an inhibitor of polygalacturonase which was separable from the enzyme by isoelectric focusing. The inhibitor was macromolecular, polydisperse and heat-labile, and its activity was destroyed by trypsin. Similar inhibitors. were found in other host-pathogen combinations.