We used an anti-indole acetic acid (IAA or auxin) monoclonal antibody-based immunocytochemical procedure to monitor IAA level in Arabidopsis tissues. Using immunocytochemistry and the IAA-driven beta-glucuronidase (GUS) activity of Aux/IAA promoter::GUS constructs to detect IAA distribution, we investigated the role of polar auxin transport in vascular differentiation during leaf development in...

The concentration of free indoleacetic acid (IAA) is high in cotton (Gossypium hirsutum L.) fruiting forms before anthesis, but is low at and for a few days after anthesis. Amide-linked and ester IAA were measured in fruiting forms at 9, 6, and 3 days before anthesis; at anthesis; and at 2, 4, 7, and 9 days after anthesis to determine if free IAA decreased because it was converted to a conjugat...

Avena coleoptile curvature is promoted by indoleacetic acid (IAA) IAA-glucoside, and IAA-inositol when these substances are applied in agar to the decapitated apical end of deseeded plantlets. Absorption of [(3)H]IAA-inositol over a wide range of concentrations during the 20 hour period of incubation is only 20 to 50% of the applied amount, compared with 85 to 92% of uptake of the applied [(3)H...

A subset of children develops persistent insulin autoantibodies (IAA; almost always as the only islet autoantibody) without evidence of progression to diabetes. The aim of the current study was the development and characterization of the performance of a nonradioactive fluid phase IAA assay in relation to standard IAA radioassay. We developed a nonradioactive IAA assay where bivalent IAA cross-...

Evidence that indoleacetic acid (IAA) conjugates are metabolized via enzyme-catalyzed hydrolysis to free IAA and that their biological activities are related to the rates at which they are hydrolyzed by the tissue is presented. These conclusions are based on the following observations. Slow but continuous decarboxylation of the IAA moiety of IAA-l-alanine and IAA-glycine occurs when these conju...

The physiological activity of exogenous 4-Cl-IAA, as compared to IAA, was examined in maize coleoptile segments. It was found that in this model system 4-Cl-IAA is much more active in the stimulation of elongation than IAA. Simultaneous measurements of growth and external pH indicated that administration of either IAA or 4-Cl-IAA resulted in medium acidification. The kinetics of the pH changes,...

Three auxin analogs, 4-, 5-, and 6-azido-3-indoleacetic acid (4-N(3)-IAA, 5-N(3)-IAA, and 6-N(3)-IAA) have been synthesized for use as fluorescent photoaffinity labeling agents. The pK(a) values of these compounds (4-N(3)-IAA, 4.67; 5-N(3)-IAA, 4.65; 6-N(3)-IAA, 4.66; all +/- 0.04) are experimentally indistinguishable from the pK(a) of 3-indoleacetic acid (IAA, 4.69 +/- 0.04). The auxin activit...

The variation of indole-3-acetic acid (IAA) transport along Lupinus albus L. hypocotyls was studied using decapitated seedlings and excised sections. To confirm that the mobile species was IAA and not IAA metabolites, dual isotope-labeled IAAs, [5-(3)H]IAA + [1-(14)C]IAA, were used. After apical application to decapitated seedlings, the longitudinal distribution of both isotopes at different tr...