Philosoph‐Hadas, S., Dept of Fruit and Vegetable Storage, Agricultural Research Organization, Volcani Center, Bet Dagan, 50250, Israel
Meir, S., Dept of Fruit and Vegetable Storage, Agricultural Research Organization, Volcani Center, Bet Dagan, 50250, Israel
Aharoni, N., Dept of Fruit and Vegetable Storage, Agricultural Research Organization, Volcani Center, Bet Dagan, 50250, Israel

Ethylene biosynthesis in leaf discs of tobacco (Nicotiana tabacum L. cv. Xanthi), as measured by the conversion of L‐[3,4‐14C]‐methionine to 14C2H4, was markedly inhibited by exogenous ethylene. This inhibition was accompanied by a decrease in total (free + conjugated) content of 1‐aminocyclopropane‐1‐carboxylic acid (ACC), most of which appeared in its conjugated inactive form. The autoinhibitory effect of ethylene was reversible and could be relieved by Ag+. The Ag+‐treated leaf discs, with or without ethylene, contained only free ACC at an increased level. The results suggest that in tobacco leaves, the autoinhibition of ethylene production resulted from reduction in the availability of free ACC, through both suppression of ACC formation and increased ACC conjugation. Copyright © 1985, Wiley Blackwell. All rights reserved