Metabolism of diclofop-methyl (-2-[4-(2′ ,4′-dichlorophenoxy)phenoxy] propanoate) in cell suspensions of diploid wheat (Triticum monococcum).

The metabolism of the herbicide, diclofop-methyl (methyl-2-[4-(2',4'-dichlorophenoxy)phenoxy]propanoate, in cell suspensions of resistant diploid wheat (Triticum monococcum L.) was determined 1, 8, and 24 h after treatment with 14C-diclofop-methyl. The 14C-labeled products were identified by thin layer chromatographic comparisons to appropriate standards. Eight hours after treatment with 5 μM diclofop-methyl in 0.8% acetone (neither of which were toxic to the cell suspensions) 87.2% (84.0% methanol soluble, 3.2% methanol insoluble) of the total 14C recovered (90.4%) was in the cells and 12.8% was in the medium. Major metabolites found in methanol extracts of the cells were diclofop (2-[4-(2',4'- dichlorophenoxy)phenoxy]propionic acid), diclofop hydroxylated at an undetermined position on the 2,4-dichlorophenyl ring (ring-OH diclofop), and conjugates of ring-OH diclofop. Acid hydrolysis of the conjugated metabolite(s) yielded ring-OH diclofop and diclofop. Twenty-four hours after treatment 70-75% of the total 14C recovered was present as conjugated metabolites. With the exception of ring-OH diclofop, all metabolites present in the cells were also recovered from the medium. A metabolite found in low concentrations in the medium that yielded diclofop upon hydrolysis was identified as an ester conjugate. Toxic concentrations of diclofop-methyl (10 and 20μM) had no effect on the metabolism of the herbicide, although the rate of uptake was slower than for cells treated with 5 μM herbicide. The products of diclofop-methyl metabolism in cell suspensions of T. monococcum were compared to previous data from T. aestivum intact plant metabolism of diclofop-methyl. [ABSTRACT FROM AUTHOR]