Media type: E-Article Title: The action of herbicides on fatty acid biosynthesis and elongation in barley and cucumber Contributor: Yang, Xueying; Guschina, Irina A; Hurst, Samantha; Wood, Sophie; Langford, Mike; Hawkes, Tim; Harwood, John L imprint: Wiley, 2010 Published in: Pest Management Science Language: English DOI: 10.1002/ps.1944 ISSN: 1526-498X; 1526-4998 Keywords: Insect Science ; Agronomy and Crop Science ; General Medicine Origination: Footnote: Description: <jats:title>Abstract</jats:title><jats:p><jats:bold>BACKGROUND:</jats:bold> Herbicides that affect lipid metabolism have been used commercially for many years. Here, napropamide, diphenamid, dimethachlor and cafenstrole are compared; these have all been classified by the Herbicide Resistance Action Committee (HRAC) as K<jats:sub>3</jats:sub> herbicides and inhibitors of cell division and/or synthesis of very‐long‐chain fatty acids (VLCFAs). In addition, spiro‐decanedione A and pinoxaden dione are compared as inhibitors of lipid synthesis through inhibition of acetyl‐CoA carboxylase (ACCase).</jats:p><jats:p><jats:bold>RESULTS:</jats:bold> Whereas the chloracetamide dimethachlor and the carboxyamide cafenstrole potently inhibited VLCFA synthesis in both barley and cucumber, the acetamides napropamide and diphenamid which are also classified as K<jats:sub>3</jats:sub> herbicides and likewise the unclassified herbicide cinmethylin did not. The graminicide pinoxaden dione inhibited <jats:italic>de novo</jats:italic> fatty acid synthesis in barley, but not in cucumber, and correspondingly inhibited the plastid form of maize ACCase much more than the cytosolic form (IC<jats:sub>50</jats:sub> values of 0.1 and 17 µ<jats:sc>M</jats:sc>). By contrast, spiro‐decanedione A exhibited herbicidal effects not only on grasses but also on broad leaves, strongly inhibited maize cytosolic ACCase and inhibited synthesis of VLCFAs in cucumber.</jats:p><jats:p><jats:bold>CONCLUSIONS:</jats:bold> The acetamides napropamide and diphenamid, which do not inhibit VLCFA synthesis, should be classified separately from K<jats:sub>3</jats:sub> herbicides that do. Pinoxaden dione and spiro‐decanedione A represent new classes of chemicals acting on plant lipid synthesis. Copyright © 2010 Society of Chemical Industry</jats:p>