The role of ethanol and acetaldehyde in flower senescence and fruit ripening - A review

Ethanol and acetaldehyde are present in carnation flowers during the senesc ence process. If applied to cut carnations, flower longevity is increased. These same compounds are found in increasing concentrations during fruit ri pening, and the application of acetaldehyde can promote the ripening proces s. If the natural concentrations are increased by means of external applica tion of either acetaldehyde or ethanol, ripening of some fruits may be inhi bited. Acetaldehyde apparently inhibits the formation of ethylene, by preve nting the action of ACC synthase and ACC oxidase. Low concentrations of eth anol may prevent normal climacteric respiration from occurring. If ethanol is present in high concentrations, it leads to increased membrane permeabil ity and damages the lipid bilayers, where the site of ethylene action is su spected to be. The effect of both acetaldehyde and ethanol on binding sites , respiration and ethylene production are reviewed. An attempt is also made to provide some understanding of the interrelationship between ethanol and acetaldehyde. The role played by alcohol dehydrogenase in this relationshi p remains largely unexplored.