Metabolism and distribution of dibutyl phthalate in wheat grown on different soil types

Herein, we investigated the distribution of dibutyl phthalate (DBP) in the tissues of wheat grown on DBP-contaminated soils and determined the activity of detoxifying enzymes [cytochrome P450 (P450) and glutathione S-transferase (GST)] in these tissues at different growth stages of wheat. The content of DBP in wheat grown on all soil types increased with increasing DBP stress concentration, and the DBP content of each tissue decreased as wheat growth progressed. Under the same conditions, the DBP content of roots exceeded that of leaves and stems, and the DBP content of all tissues decreased in the order of brown soil > fluvo-aquic soil > cinnamon soil. The decrease of DBP content with growth and the content of mono-n-butyl dicarboxylate (MBP, main metabolite of DBP) followed the order of cinnamon soil > fluvo-aquic soil > brown soil; the latter parameter initially increased and then decreased as growth progressed. The changes in P450 content and GST activities in wheat tissues were highly consistent with the corresponding changes in DBP and MBP content, except for the DBP stress level of 40 mg kg^-1 at the seedling stage. Based on the obtained results, it was speculated that P450 and GST were strongly involved in the metabolism of DBP in wheat: oxygen atoms were inserted into the aldehyde C-H bond of the species generated after hydrolysis of ester groups under the action of P450 to achieve hydrocarbon hydroxylation under mild conditions and generate MBP.