A procedure was developed for introducing tritium into the side chain of the abscisic acid (ABA) molecule. The reaction was carried out in dioxane in the presence of the Lindlar catalyst. The yield ...of the labeled product was 70% and the molar radioactivity was 44 Ci/mol. The tritium-labeled abscisic acid analogue was found to be a growth substrate for soil bacteria that incorporate a radioactive label into cellular metabolites. The absorption of the label by bacteria from the side chain of abscisic acid is more than an order of magnitude higher than that for labeling in the cyclohexene moiety. The results indicate the existence of a previously unknown metabolism pathway of ABA in microorganisms.
