Summary and Additional Reading

Fatty acid synthesis and elongation are highly important pathways in plants because the endproducts are critical components of membranes, cutinsuberin, and waxes.  Fatty acid synthesis (chain length up to 18 carbons) is inhibited by the aryloxyphenoxy propionate and cyclohexanedione herbicide families, which inhibit acetyl CoA-carboxylase (ACCase), the first enzyme of the pathway.  Fatty acid elongation (16 and 18 carbon fatty acids are elongated up to 34 carbons) is inhibited by the carbamothioate and chloroacetamide herbicides.  Resistance to these groups of herbicides has been selected for in several weedy species.  The resistance mechanisms are varied, ranging from an altered enzyme binding site (most ACCase resistance), to enhanced herbicide metabolism (other ACCase resistant biotypes), to reduced metabolic activation of a pro-herbicide (carbamothioate resistance).  


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