Three metabolites of indole-3-acetic acid (IAA), N-(6-hydroxyindol-3-ylacetyl)-phenylalanine (6-OH-IAA-Phe), N-(6-hydroxyindol-3-ylacetyl)-valine (6-OH-IAA-Val), and 1-O-(2-oxoindol-3- ylacetyl)-β-d-glucopyranose (OxIAA-Glc), were found by a liquid chromatography- electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS)-based search for oxidative IAA metabolites during the vegetative growth of Arabidopsis. Their structures ...