PLANT PHYSIOLOGY , Vol 113, Issue 2 431-439, Copyright © 1997 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Acetaldehyde Is a Causal Agent Responsible for Ethanol-Induced Ripening Inhibition in Tomato Fruit
J. C. Beaulieu, G. Peiser and M. E. Saltveit
Department of Vegetable Crops, Mann Laboratory, University of California, Davis, California 95616-8631
Inhibition of tomato (Lycopersicon esculentum Mill.) fruit ripening by
exogenously applied ethanol was shown to be caused by elevated endogenous
levels of acetaldehyde (AA). Exposure of excised pericarp discs of
mature-green tomato fruit to ethanol or AA vapors produced elevated levels
of both compounds in the tissue, but only the levels of AA were associated
with ripening inhibition. Ripening inhibition was dependent on both the
applied concentration and the duration of exposure. Discs treated with
inhibitory levels of AA had levels of ethanol that were elevated but below
that associated with inhibition of ripening. The in vivo activity of
alcohol dehydrogenase was inhibited 40 to 60% by 4-methylpyrazole (4-MP), a
competitive inhibitor of this enzyme. The inhibitory effect of ethanol on
ripening was reduced by the simultaneous application of 4-MP. Tissue
treated with 4-MP plus AA vapors had higher endogenous levels of AA and
ripening was inhibited longer than in tissue without 4-MP. The tissue AA
level resulting from ethanol or AA application appears to be the critical
determinant of ripening inhibition.