Ethylene Production by Cytoplasmic Particles from Apple and Tomato Fruits in the Presence of Thiomalic and Thioglycolic Acid

Abstract

DESPITE several tracer studies^1,2 and the use of very sensitive techniques for the detection of ethylene^3,4, there has been no clear indication of a biosynthetic pathway that can evolve ethylene in fruits. Spencer⁵ reported ethylene production by cytoplasmic particles from tomato fruit in the presence of malate and co-factors. This suggested that the biosynthesis of ethylene could be related to the metabolism of organic acids in the cells. Tracer experiments by Burg², however, showed no evidence linking ethylene evolution to Krebs cycle metabolism. Meigh et al.⁴ could not detect ethylene in incubation mixtures containing apple mitochondria, malate and co-factors. The latter experiments are especially significant since they used apple mitochondria known to metabolize Krebs-cycle substrates, and the system for detecting ethylene was considerably more sensitive than that used in any of the other investigations. It therefore appears that ethylene synthesis in fruits must be associated with some other aspect of organic acid metabolism.