Abstract
Metabolism of indole-3-acetic acid (IAA) in Arabidopsis was quantitatively analyzed. The metabolites covered were: IAA-Asp, IAA-Glu, IAA-glucose, 2-oxoindole-3-acetic acid (OxIAA), OxIAA-Asp, and OxIAA-Glu. Standard samples of IAA-Asp and -Glu were synthesized by the condensation of IAA with the respective amino acids. IAA-glucose was synthesized using tetrabenzylglucosylimidate as a reagent. OxIAA was prepared by oxidation of IAA, which was then condensed with amino acids to afford OxIAA-Asp and -Glu. The sample tissues from 2-week-old Arabidopsis were soaked in methanol, and then in 90% methanol in water. Combined extracts were partially purified using C18-solid-phase extraction cartridge. The fraction containing target compounds was subjected to LC/MS/MS operated in multiple reaction monitoring mode. The levels of above metabolites were determined according to the calibration curves. Furthermore, novel metabolites of IAA were searched for by using MS/MS detection modes in combination. The presence of previously undescribed metabolites was suggested.
