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

Ethanol and acetaldehyde are present in carnation flowers during the senescence process. If applied to cut carnations, flower longevity is increased. These same compounds are found in increasing concentrations during fruit ripening, and the application of acetaldehyde can promote the ripening process. If the natural concentrations are increased by means of external application of either acetaldehyde or ethanol, ripening of some fruits may be inhibited. Acetaldehyde apparently inhibits the formation of ethylene, by preventing the action of ACC synthase and ACC oxidase. Low concentrations of ethanol may prevent normal climacteric respiration from occurring. If ethanol is present in high concentrations, it leads to increased membrane permeability and damages the lipid bilayers, where the site of ethylene action is suspected 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 relationship remains largely unexplored.