Ethylene: A Factor in Defoliation Induced by Auxins

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Science  07 Mar 1969:
Vol. 163, Issue 3871, pp. 1067-1068
DOI: 10.1126/science.163.3871.1067


Aerial sprays of synthetic auxins defoliate many species of tropical trees. Treatment of Euonymus japonica leaves with the n-butyl ester of 2,4-dichlorophenoxyacetic acid causes premature senescence and leaf fall and stimulates ethylene production by the blade 5-to 25-fold. Exposure to ethylene alone similarly accelerates senescence and leaf fall. Evidence indicates that the defoliant action of auxin is mediated through the enhanced amounts of ethylene in the blade.