Showing papers by "John L. Harwood published in 1988"

Fluazifop, a grass-selective herbicide which inhibits acetyl-CoA carboxylase in sensitive plant species.

Abstract: Fluazifop is a grass-selective herbicide that appears to act by inhibiting fatty acid synthesis de novo in sensitive species. Results from four different types of experiment show that this inhibition is due to an action of fluazifop on acetyl-CoA carboxylase and not on fatty acid synthetase. The acetyl-CoA carboxylase from sensitive barley (Hordeum vulgare), but not from resistant pea (Pisum sativum), is inhibited by the R stereoisomer, a finding that agrees with the herbicidal specificity of fluazifop.

Effects of the selective herbicide fluazifop on fatty acid synthesis in pea (Pisum sativum) and barley (Hordeum vulgare).

Abstract: Concentrations of fluazifop-butyl sprayed on intact plants caused large decreases in the incorporation of radioactivity from [1-14C]acetate into lipids of barley (Hordeum vulgare) leaves and stems, but did not affect leaves or stems of pea (Pisum sativum). Labelling of all acyl lipids, but not pigments, was reduced. The effects of the active acid form, fluazifop, were also determined in leaf pieces and chloroplasts. Concentrations of (R,S)-fluazifop up to 100 microM had no affect upon quality or quantity of fatty acids produced from [1-14C]acetate in pea. In barley, however, 100 microM-(R,S)-fluazifop caused 89% (leaf) or 100% (chloroplasts) inhibition in labelling of fatty acids from [1-14C]acetate. Lower concentrations of fluazifop (less than 25 microM) caused incomplete inhibition and significant decreases in the proportion of C18 fatty acids synthesized, particularly by isolated chloroplasts. Synthesis of fatty acids from [2-14C]malonate was also inhibited (59%) in barley leaf tissue by 100 microM-(R,S)-fluazifop. The labelling pattern of products showed that elongation reactions were unaffected by the herbicide, but synthesis de novo was specifically diminished. By using resolved stereoisomers, it was found that the (R) isomer was the form which inhibited fatty acid synthesis, a finding that is in agreement with its herbicidal activity. These results suggest that inhibition of fatty acid synthesis de novo forms the basis for the selective mode of action of fluazifop.

Effects of heavy metals on lipid metabolism in marine algae

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