Analysis of [¹⁴C] indole‐3‐acetic acid metabolites from the primary roots of Zea mays seedlings using reverse‐phase high‐performance liquid chromatography

Abstract

Methanolic extracts of Zea mays L. cv. Fronica root segments which had been incubated in [14C] indole‐3‐acetie acid were analysed by reverse‐phase high‐performance liquid chromatography. Metabolism of indole‐3‐acetic acid was found to be rapid and extensive with at least 11 products apparent after a 2 h incubation. A comparison of metabolites of [1‐14C]– and [2‐14C] IAA, calculations of 14CO2 evolution, and data on the polarity of products indicated that decarboxylation had not occurred. An average of 34% of the radioactivity remained associated with the indole‐3‐acetic acid peak.

Auxin Metabolism in the Root Apical Meristem

“…The reason for this conclusion is evident when one considers the plant materials (primarily shoot tissues) recently used to study auxin catabolism (Normanly, 1997;Ö stin et al, 1998). Root tissues have rarely been employed, and, when occasionally used, either the terminal 1 to 4 mm was excised prior to initiating IAA turnover experiments or the entire plant was extracted, which could lead to a masking of any decarboxylation occurring in the small amounts of tissue comprising the root tips (Nonhebel et al, 1983;Sztein et al, 1995). Additionally, when decarboxylation products have been detected in extracts, these products have often been viewed as resulting from experimentally induced (artifactual) exposure of auxin to peroxidases (Bandurski et al, 1995;Normanly, 1997;Ö stin et al, 1998).…”

Anions Activate the Oxidation of Indoleacetic Acid by Peroxidases from Tomato and Other Sources

“…The in vitro reaction catalyzed by horseradish peroxidase involves decarboxylation of IAA to yield 3-methyleneoxindole and other products (18). Although up to ten products have been identified in seedlings supplied radiolabeled IAA, the most prominent was oxindoleacetic acid (17,22). Oxindoleacetic acid has also been identified as an endogenous component of maize (23).…”

A Novel Metabolic Pathway for Indole-3-Acetic Acid in Apical Shoots of Populus tremula (L.) x Populus tremuloides (Michx.)

“…Early studies on IAA metabolism were focused mainly on in vitro peroxidase-catalyzed decarboxylative metabolism, and this pathway is now well characterized (see Sandberg et al, 1987a strated the importance of nondecarboxylative IAA metabolism in many plant tissues ( e g Davies, 1973;Nonhebel et al, 1983Nonhebel et al, , 1985bWiese and Grambow, 1986;Emstsen et al, 1987;Monteiro et al, 1988). In Zea mays, nondecarboxylative metabolism of IAA to 7-Gluc-OxIAA via OxIAA and 7-OHOxIAA has been established Bandurski, 1981, 1983;Nonhebel and Bandurski, 1984;Nonhebel et al, 1985a;Lewer, 1987;Lewer and Bandurski, 1987).…”