Ethylene-Like Activity of Isocyanides

Benzyl isocyanide, cyclohexyl isocyanide, benzyl isocyanate, methyl isocyanate, benzyl isothiocyanate, and methyl isothiocyanate were each tested for ethylene-like activity in a pea (Pisum sativum) growth assay. Only the isocyanides gave an ethylene-like response; the concentration that gave a half-maximal response was approximately 10 to 15 microliters per liter for each isocyanide, and this activity was inhibited by norbornadiene, a competitive inhibitor of ethylene action. Since the isocyanides did not promote endogenous ethylene production, it was concluded that the isocyanides acted directly to give an ethylene-like response. The isocyanides were further shown to elicit ethylene-like activity in a potato (Solanum tuberosum) tuber respiration assay, in a carnation (Dianthus caryophyllus) senescence assay and in a carrot (Daucus carota L.) isocoumarin formation assay. The feasibility of employing azido derivatives of benzyl isocyanide to photoaffinity label ethylene receptors in vivo is discussed.