title: Fermentation and alternative oxidase contribute to the action of amino acid biosynthesis-inhibiting herbicides.
abstract: Acetolactate synthase inhibitors (ALS-inhibitors) and glyphosate (GLP) are two classes of herbicide that act by the specific inhibition of an enzyme in the biosynthetic pathway of branched-chain or aromatic amino acids, respectively. The physiological effects that are detected after application of these two classes of herbicides are not fully understood in relation to the primary biochemical target inhibition, although they have been well documented. Interestingly, the two herbicides' toxicity includes some common physiological effects suggesting that they kill the treated plants by a similar pattern despite targeting different enzymes. The induction of aerobic ethanol fermentation and alternative oxidase (AOX) are two examples of these common effects. The objective of this work was to gain further insight into the role of fermentation and AOX induction in the toxic consequences of ALS-inhibitors and GLP. For this, Arabidopsis T-DNA knockout mutants of alcohol dehydrogenase (ADH) 1 and AOX1a were used. The results found in wild-type indicate that both GLP and ALS-inhibitors reduce ATP production by inducing fermentation and alternative respiration. The main physiological effects in the process of herbicide activity upon treated plants were accumulation of carbohydrates and total free amino acids. The effects of the herbicides on these parameters were less pronounced in mutants compared to wild-type plants. The role of fermentation and AOX regarding pyruvate availability is also discussed.
authors.affiliation: Departamento Ciencias del Medio Natural, Universidad Pública de Navarra, Campus Arrosadía, E-31006 Pamplona, Spain.
authors.forename: Amaia
authors.initials: A
authors.lastname: Zulet
authors.affiliation: Departamento Ciencias del Medio Natural, Universidad Pública de Navarra, Campus Arrosadía, E-31006 Pamplona, Spain.
authors.forename: Miriam
authors.initials: M
authors.lastname: Gil-Monreal
authors.affiliation: Departamento Ciencias del Medio Natural, Universidad Pública de Navarra, Campus Arrosadía, E-31006 Pamplona, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Zabalza
authors.affiliation: Institute of Biology 1, RWTH Aachen University, Worringerweg 1, D 52074 Aachen, Germany.
authors.forename: Joost T
authors.initials: JT
authors.lastname: van Dongen
authors.affiliation: Departamento Ciencias del Medio Natural, Universidad Pública de Navarra, Campus Arrosadía, E-31006 Pamplona, Spain. Electronic address: royuela@unavarra.es.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Royuela
mesh_terms: D000095:Acetolactate Synthase / Q000037:antagonists & inhibitors / Q000235:genetics; D000596:Amino Acids / Q000096:biosynthesis; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000037:antagonists & inhibitors / Q000235:genetics; D005285:Fermentation; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006540:Herbicides / Q000494:pharmacology*; D024101:Mitochondrial Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D016254:Mutagenesis, Insertional; D010088:Oxidoreductases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D010940:Plant Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D019289:Pyruvic Acid / Q000378:metabolism; D000097797:Glyphosate; D000099188:Alternative Oxidase
chemical_list: D000095:Acetolactate Synthase; D000596:Amino Acids; D029681:Arabidopsis Proteins; D005998:Glycine; D006540:Herbicides; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010100:Oxygen; D010940:Plant Proteins; D019289:Pyruvic Acid; D000097797:Glyphosate; D000099188:Alternative Oxidase
keywords: Acetolactate synthase inhibitors; Arabidopsis thaliana; Ethanol fermentation; Glyphosate; Physiological effects