The Metabolism of Acetaldehyde by Plant Tissues

Apples and oranges can absorb appreciable amounts of acetaldehyde vapour, but acetaldehyde does not accumulate in the tissues, in the presence or absence of oxygen. When the fruit is given acetaldehyde the loss of carbon as CO2 + ethanol equals that lost from carbohydrate + acid+acetaldehyde. Part of the added acetaldehyde is reduced to ethanol by NADH2 and the rate of glycolysis is increased; the remainder is oxidized to CO2. Respiration of apples is limited by oxygen; the output of CO2 is only slightly increased at the beginning of the treatment with acetaldehyde, but afterwards it declines; acetaldehyde spares oxidation of carbohydrate. In oranges, availability of substrate limits respiration, and acetaldehyde stimulates CO2-production and O2-uptake. In the absence of oxygen, acetaldehyde is reduced to ethanol, and the quotient CO2/ethanol falls.