title: Characterization of the Amaranthus palmeri Physiological Response to Glyphosate in Susceptible and Resistant Populations.
abstract: The herbicide glyphosate inhibits the plant enzyme 5-enolpyruvylshikimate3-phosphate synthase (EPSPS) in the aromatic amino acid (AAA) biosynthetic pathway. The physiologies of an Amaranthus palmeri population exhibiting resistance to glyphosate by EPSPS gene amplification (NC-R) and a susceptible population (NC-S) were compared. The EPSPS copy number of NC-R plants was 47.5-fold the copy number of NC-S plants. Although the amounts of EPSPS protein and activity were higher in NC-R plants than in NC-S plants, the AAA concentrations were similar. The increases in total free amino acid and in AAA contents induced by glyphosate were more evident in NC-S plants. In both populations, the EPSPS protein increased after glyphosate exposure, suggesting regulation of gene expression. EPSPS activity seems tightly controlled in vivo. Carbohydrate accumulation and a slight induction of ethanol fermentation were detected in both populations.
authors.affiliation: Departamento Ciencias del Medio Natural, Universidad Pública de Navarra , Campus Arrosadı́a, E-31006 Pamplona, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Fernández-Escalada
authors.affiliation: Departamento Ciencias del Medio Natural, Universidad Pública de Navarra , Campus Arrosadı́a, 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 Arrosadı́a, E-31006 Pamplona, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Zabalza
authors.affiliation: Departamento Ciencias del Medio Natural, Universidad Pública de Navarra , Campus Arrosadı́a, E-31006 Pamplona, Spain.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Royuela
mesh_terms: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase / Q000235:genetics / Q000378:metabolism; D027721:Amaranthus / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D018628:Gene Dosage; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D053209:Herbicide Resistance; D006540:Herbicides / Q000494:pharmacology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D000097797:Glyphosate
chemical_list: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D005998:Glycine; D006540:Herbicides; D010940:Plant Proteins; D000097797:Glyphosate
keywords: carbohydrate accumulation; ethanol fermentation; free amino acid accumulation; herbicide resistance; physiological effects