Correlation of virulence with secretion in vitro of three wall-degrading enzymes in isolates of Sclerotinia fructigena obtained after mutagen treatment.

Correlation and regression analyses were carried out between the virulence (expressed as growth rate in apple fruits) and the secretion in vitro of three host wall-degrading enzymes by 119 isolates of Sclerotinia fructigena, most of which had been obtained following exposure of conidia to N-methyl-N'-nitro-N-nitroso-guanidine. Virulence was found to be significantly correlated (P less than 0-01) with alpha-L-arabinofuranosidase, but not with pectin esterase or, where enzyme interdependence had been statistically eliminated, with polygalacturonase. Approximately 35% of the total variability in virulence could be accounted for in terms of the three enzymes.