Pectin Methyl-trans-eliminase as the Maceration Factor of Sclerotinia fructigena and Its Significance in Brown Rot of Apple

Abstract

SUMMARY: Good correlation between pectin methyl-trans-eliminase (PTE) activity and the ability to macerate plant tissue slices was found in fractions obtained from culture filtrates of the fungus Sclerotinia fructigena by gel filtration on dextran gel, or by ion-exchange chromatography. The presence of two isoenzymes was indicated, one of which was markedly activated by sodium polypectate or potato extract. Endo-polygalacturonase and α-L-arabinofuranosidase activities were not correlated with macerating ability. Negligible amounts of PTE were, however, detected in extracts of apple fruitlets rotted by S. fructigena; the pH optima of the enzyme components in the culture filtrates differed greatly from the pH of apple tissue. For this and other reasons PTE would appear to have little, and at most very localized, significance in the infection of apple fruits by S. fructigena.