Overview of herbicide mechanisms of action.
Commercial herbicides exhibit many different mechanisms of action. Several enzymes involved in biosynthesis of amino acids are sites of action for herbicides. A large number of different herbicide classes inhibit photosynthesis by binding to the quinone-binding protein, D-1, to prevent photosynthetic electron transfer. Several different types of herbicides apparently cause accumulation of photodynamic porphyrins by inhibiting protoporphyrinogen oxidase. Bipyridyliums and heteropentalenes cause the production of superoxide radicals by energy diversion from photosystem I of photosynthesis. Lipid synthesis is the site of action of a broad array of herbicides used in controlling monocot weeds. Herbicides of several classes apparently act by inhibiting mitosis through direct interaction with tubulin. Several other molecular sites of herbicide action are known. Despite a growing body of knowledge, the exact molecular sites of action of many herbicides are unknown. Some herbicides are known to have more than one site of action. Virtually all knowledge of herbicide structure-activity relationships is semiempirical. In addition to site of action structure-activity relationships, herbicide structure and chemical properties also strongly influence absorption, translocation, bioactivation, and environmental stability. Considering how little is known about all the potential sites of herbicide action, it is unlikely that during the next decade more than a relatively small number of site-specific herbicide structure-activity relationships will be developed.
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U.S. Department of Agriculture, Southern Weed Science Laboratory, Stoneville, MS 38776.
D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D000095:Acetolactate Synthase / Q000037:antagonists & inhibitors; D019883:Alkyl and Aryl Transferases; D000596:Amino Acids / Q000096:biosynthesis; D002338:Carotenoids / Q000096:biosynthesis; D005609:Free Radicals; D005974:Glutamate-Ammonia Ligase / Q000037:antagonists & inhibitors; D006540:Herbicides / Q000737:chemistry / Q000145:classification / Q000493:pharmacokinetics / Q000494:pharmacology*; D008055:Lipids / Q000096:biosynthesis; D008870:Microtubules / Q000187:drug effects; D008938:Mitosis / Q000187:drug effects; D010088:Oxidoreductases / Q000037:antagonists & inhibitors; D044925:Oxidoreductases Acting on CH-CH Group Donors; D010573:Pesticide Residues; D010788:Photosynthesis / Q000187:drug effects; D045322:Photosynthetic Reaction Center Complex Proteins / Q000037:antagonists & inhibitors; D045331:Photosystem I Protein Complex; D010940:Plant Proteins / Q000037:antagonists & inhibitors; D050768:Protoporphyrinogen Oxidase; D013329:Structure-Activity Relationship; D013481:Superoxides / Q000378:metabolism; D014166:Transferases / Q000037:antagonists & inhibitors
D000596:Amino Acids; D005609:Free Radicals; D006540:Herbicides; D008055:Lipids; D010573:Pesticide Residues; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010940:Plant Proteins; D013481:Superoxides; D002338:Carotenoids; D010088:Oxidoreductases; D044925:Oxidoreductases Acting on CH-CH Group Donors; D050768:Protoporphyrinogen Oxidase; D014166:Transferases; D000095:Acetolactate Synthase; D019883:Alkyl and Aryl Transferases; D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D005974:Glutamate-Ammonia Ligase