Cellulase activity and ethylene in ripening strawberry and apple fruits

A six-fold increase in cellulase activity, measured as the reduction in viscosity of carboxymethyl cellulose, was associated with maturation and softening in strawberry fruit. Applied ethylene did not increase cellulase levels in harvested strawberry fruit. This agrees with earlier findings that ethylene does not appear to regulate strawberry ripening. In apple, an ethylene-sensitive fruit, a decrease in cellulase activity was observed in fruit allowed to ripen on the tree.