Indoleacetic Acid Oxidizing Enzyme & Inhibitors from Light-Grown Cotton

As one aspect of a study of abscission in the cotton plant, we have been interested in the possible presence of an indoleacetic acid (IAA) oxidase in the aerial portions of the green plant. The need for investigation was indicated by the possibility that IAA oxidase could affect the decline in detectable auxin in cotton which occurs just prior to leaf fall (1, 2). A study was initiated after noting that although there is evidence for the occurrence of IAA in cotton (3, 12), a preliminary attempt to demonstrate IAA oxidase was unsuccessful (13). Furthermore, information on the occurrence of the enzyme in other -green tissues was relatively limited and an unequivocal function of the enzyme in higher plants has not been clearly established. This paper presents evidence for the occurrence of an IAA oxidase in cotton and some characteristics of the enzyme and an inhibitor(s).