Inhibition of lipid synthesis by diclofop-methyl is age dependent in roots of oat and corn.
1993
Di Tomaso J.M. | Stowe A.E. | Brown P.H.
The effect of diclofop-methyl on lipid synthesis in entire oat (Avena sativa L. "Prior") and corn (Zea mays L. "3377 Pioneer") roots, in 1-cm corn root tips, and in corn shoots were examined at 24-hr intervals within a 4-day period. In addition, the de novo synthesis of specific lipids was compared in untreated and diclofop-methyl-treated whole roots and 1-cm root tips of corn seedlings. The overall rate of [14C]acetic acid incorporation into lipids in the entire root system of both oat and corn was not affected by diclofop-methyl. This response was evident up to 96 hr after treatment, despite a complete reduction in root growth 24 hr after herbicide exposure. In contrast, incorporation of [14C]acetic acid into lipids was greatly reduced in corn root tips (70% inhibition) after 24 hr and in corn shoots (52% inhibition) after a 48-hr treatment period. Thin-layer chromatographic separation and subsequent quantification of radiolabeled lipids indicated that 0.8 micromolar diclofop-methyl primarily inhibited the synthesis of di- and triglycerides in both root tips and in intact roots. However, the incorporation of [14C]acetic acid into several other lipids, including glycolipids and phospholipids, was stimulated in mature root tissues treated with diclofop-methyl. This supports the view that mature root tissues of sensitive species are not damaged by growth-inhibiting concentrations of diclofop-methyl and that herbicidal activity must be coupled to growth processes.
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