Inhibition of Ethylene Synthesis and Action in Ripening Tomato Fruit by Ethanol Vapors

Exposure of whole fruit, slices, or pericarp disks of tomato ( Lycopersicon esculentum Mill.) to 0.5 to 3.0 ml absolute ethanol vaporized in a 4-Iiter container for 3 hr significantly reduced the climacteric rise in CO 2 and C 2 H 4 production, lycopene synthesis, and chlorophyll loss. Inhibition of ripening occurred whether fruit were at the mature-green or breaker-turning stage. Whole fruit recovered and ripened normally after a delay that was related to the tissue ethanol concentration. Treated slices did not ripen normally, and exposure to 16 μl C 2 H 4 /liter did not promote ripening. The level of ACC was 14-fold higher in treated slices, while C 2 H 4 production was reduced 70%. Treatments with AVG and ACC indicated that ethanol inhibited ACC conversion to C 2 H 4 . Chemical names used: 1-aminocyclopropane-1-carboxylic acid (ACC); [ S -( E )]-2-amino-4-(2-aminoethoxy)-3-butyric acid (AVG).