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Plant Physiology 70:162-167 (1982) © 1982 American Society of Plant Biologists Ethylene Biosynthesis and Cadmium Toxicity in Leaf Tissue of Beans (Phaseolus vulgaris L.) 1School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511
Stress ethylene production in bean (Phaseolus vulgaris L., cv. Taylor's Horticultural) leaf tissue was stimulated by Cd2+ at concentrations above 1 micromolar. Cd2+-induced ethylene biosynthesis was dependent upon synthesis of 1-aminocyclopropane-1-carboxylic acid (ACC) by ACC synthase. Activity of ACC synthase and ethylene production rate peaked at 8 h of treatment. The subsequent decline in enzyme activity was most likely due to inactivation of the enzyme by Cd2+, which inhibited ACC synthase activity in vitro at concentrations as low as 0.1 micromolar. Decrease in ethylene production rate was accompanied by leakage of solutes and increasing inhibition of ACC-dependent ethylene production. Ca2+, present during a 2-hour preincubation, reduced the effect of Cd2+ on leakage and ACC conversion. This suggests that Cd2+ exerts its toxicity through membrane damage and inactivation of enzymes. The possibility of an indirect stimulation of ethylene biosynthesis through a wound signal from injured cells is discussed.
2 Present address: Institute of Plant Physiology, University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland. 1 Supported by a Swiss National Science Foundation Postdoctoral Fellowship. This article has been cited by other articles:
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