Figure 5.

Profiling of IAA Metabolites after Feeding with Radiolabeled IAA.

Radioactivity profiles are shown for IAA metabolites in extracts from whole seedlings (A), intact root tips (B), and isolated root tip protoplasts (C) after feeding 7-DAG Arabidopsis wild-type Col-0 seedlings with [1′-¹⁴C]IAA. IAA and its metabolites were separated using HPLC, and the radioactivity in dpm was monitored using scintillation counting. After feeding of whole seedlings (A), almost all of the [1′-¹⁴C]IAA that was taken up was rapidly degraded to radioactive oxIAA-Glc (peak 1), oxIAA (peak 2), IAA-Asp (peak 3), IAA-Glu (peak 4), and IAA-Ala (peak 5), and very little radioactive IAA (peak 6) was remaining in the extract. Radioactive IAA applied to excised roots was quickly transported down to the root apex and metabolized into mainly oxIAA and oxIAA-Glc (B). In isolated protoplasts, oxIAA was the major metabolite observed (C).