Inactivity of Hexitols & Hexoses in Biosynthesis of Auxin From Tryptophan

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Abstract
Certain sugar alcohols, like auxins, interact synergistically with kinins in the growth of carrot phloem tissue. Since phenolic ortho-diols form oxidants that convert tryptophan to auxin, the morphogenic action of hexitols in tissue cultures could conceivably come from an increase in auxin supply. Enzyme preparations were made from tissues of carrot, Coleus, mung bean, Avena, and mouse liver. These preparations could convert tryptophan. Under conditions of substrate saturation and linear rates of indoleacetic acid (IAA) formation, the addition of D-sorbitol, m-inositol, D-glucose, fructose and sucrose caused no acceleration of the production of either IAA or of other auxins. It is inferred that the hexitols interact with kinin-like factors in some manner other than by converting tryptophan to auxin. The inactivity of the carbohydrates tested suggests that a carbocyclic as well as unsaturated ring structure is required by the vicinal hydroxy compounds that degrade tryptophan to IAA.