Ethylene induced isoperoxidase changes during fiber formation in postharvest asparagus

Excision of asparagus spears triggered increased peroxidase activity and a shift in isozyme species. Changes in peroxidase occurred within 8 hr after harvest at the cut end of the spear and progressed to the tip end after 24 hr storage at 20 °C and 85% relative humidity. Isozyme changes were accelerated by exogenous ethylene gas. Ethylene production by cut spears and rate of spear toughening were greatest when spears were cut above ground. It is suggested that wound ethylene triggers a shift in peroxidase isozymes which participate in lignin biosynthesis and results in spear toughening after harvest.