Abstract
High performance liquid chromatography of extracts of tomato (Lycopersicon esculentum Mill.) incubated with a relatively low concentration (4 μm) of [1-14C]indole-3-acetic acid (IAA) revealed the presence of two major polar metabolites. Hydrolysis of the two metabolites with 7 n NaOH yielded the same compound, which had a retention time similar to that of ring-expanded oxindole-3-acetic acid (OxIAA) on high performance liquid chromatography. The identity of the indolic moiety of these conjugates as OxIAA was further confirmed by gas chromatography-mass spectrometry. Chromatography of the two OxIAA conjugates on a calibrated Bio-Gel P-2 column indicated that their molecular weights are about 1200 and 1000. Aspartic acid and glutamic acid were the major amino acids detected in acid hydrolysates of the two conjugates. Increasing the concentration of IAA in the incubation medium resulted in an increase in the formation of indole-3-acetylaspartic acid (IAAsp) with a concomitant decrease in the formation of the two OxIAA conjugates. Feeding experiments with labeled IAAsp and OxIAA showed that IAAsp and not OxIAA is the precursor of these conjugates. The data obtained indicate that exogenous IAA is converted in tomato pericarp tissue to high molecular weight conjugates, presumably peptides, of OxIAA via the oxidation of IAAsp. The oxidation of IAAsp seems to be a rate-limiting step in the formation of these conjugates from exogenous IAA.
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- Bandurski R. S., Schulze A. Concentration of Indole-3-acetic Acid and Its Derivatives in Plants. Plant Physiol. 1977 Aug;60(2):211–213. doi: 10.1104/pp.60.2.211. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bialek K., Cohen J. D. Isolation and Partial Characterization of the Major Amide-Linked Conjugate of Indole-3-Acetic Acid from Phaseolus vulgaris L. Plant Physiol. 1986 Jan;80(1):99–104. doi: 10.1104/pp.80.1.99. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Epstein E., Baldi B. G., Cohen J. D. Identification of Indole-3-Acetylglutamate from Seeds of Glycine max L. Plant Physiol. 1986 Jan;80(1):256–258. doi: 10.1104/pp.80.1.256. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Nonhebel H. M., Kruse L. I., Bandurski R. S. Indole-3-acetic acid catabolism in Zea mays seedlings. Metabolic conversion of oxindole-3-acetic acid to 7-hydroxy-2-oxindole-3-acetic acid 7'-O-beta-D-glucopyranoside. J Biol Chem. 1985 Oct 15;260(23):12685–12689. [PubMed] [Google Scholar]
- Wiesman Z., Riov J., Epstein E. Characterization and Rooting Ability of Indole-3-Butyric Acid Conjugates Formed during Rooting of Mung Bean Cuttings. Plant Physiol. 1989 Nov;91(3):1080–1084. doi: 10.1104/pp.91.3.1080. [DOI] [PMC free article] [PubMed] [Google Scholar]