Abstract
The origin of the ethylene carbon skeleton in Penicillium digitatum appears to be intimately associated with the Krebs cycle acids, particularly the middle carbon atoms of dicarboxylic acids. Among the other compounds studied, certain carbon atoms of beta-alanine, propionic acid, and methionine can be incorporated into the ethylene carbon skeleton presumably by way of an indirect route via the Krebs cycle acids. Carbon atoms of acrylic acid, particularly C-2, were also found to be incorporated into the ethylene skeleton. Inhibition of ethylene but not respiratory CO(2) formation in the mold by cis-3-chloroacrylic acid at 1 x 10(-3)m pointed to the possibility that acrylic acid may be related to the precursor for ethylene.