Catabolism of 3-indole acetic acid in protoplasts from etiolated seedlings of scots pine (Pinus sylvestris L.).

Protoplasts preparated from dark grown seedlings of Pinus sylvestris L. were incubated with 3-indole (1-(14)C) acetic acid and 3-indole (2-(14)C) acetic acid (IAA). Three catabolites were consistently produced in the (2-(14)C) IAA feeds, one of which co-chromatographed with 3-indole methanol on reversed phase high performance liquid chromatography (HPLC). Protoplasts feed with (1-(14)C) IAA produced only one labelled catabolite. The non-decarboxylated compound formed was highly polar on reversed phase HPLC, both in the ion suppression and the ion pair mode. The substance was not hydrolysable at pH 11 and 100° indicating that it is not a conjugated form. Effects of time of incubation, pH and the cofactors hydrogen peroxide and 2,4-dichlorphenol on the catabolic rate of IAA are discussed.