Fernández Escalada, Manuel

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https://academica-e.unavarra.es/handle/2454/49012

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Fernández Escalada

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Manuel

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Ciencias del Medio Natural

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750641

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810924

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2017 - 20193
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Subject: DAHPS ×

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Now showing 1 - 3 of 3
  • Thumbnail Image
    PublicationOpen Access
    The pattern of shikimate pathway and phenylpropanoids after inhibition by glyphosate or quinate feeding in pea roots
    (Elsevier, 2017) Zabalza Aznárez, Ana; Orcaray Echeverría, Luis; Fernández Escalada, Manuel; Zulet González, Ainhoa; Royuela Hernando, Mercedes; Ciencias del Medio Natural; Natura Ingurunearen Zientziak; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
    The shikimate pathway is a metabolic route for the biosynthesis of aromatic amino acids (AAAs) (i.e. phenylalanine, tyrosine, and tryptophan). A key enzyme of shikimate pathway (5-enolpyruvylshikimate-3-phosphate synthase, EPSPS) is the target of the widely used herbicide glyphosate. Quinate is a compound synthesized in plants through a side branch of the shikimate pathway. Glyphosate provokes quinate accumulation and exogenous quinate application to plants shows a potential role of quinate in the toxicity of the herbicide glyphosate. Based on this, we hypothesized that the role of quinate accumulation in the toxicity of the glyphosate would be mediated by a deregulation of the shikimate pathway. In this study the effect of the glyphosate and of the exogenous quinate was evaluated in roots of pea plants by analyzing the time course of a full metabolic map of several metabolites of shikimate and phenylpropanoid pathways. Glyphosate application induced an increase of the 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase (DAHPS, first enzyme of the shikimate pathway) protein and accumulation of metabolites upstream of the enzyme EPSPS. No common effects on the metabolites and regulation of shikimate pathway were detected between quinate and glyphosate treatments, supporting that the importance of quinate in the mode of action of glyphosate is not mediated by a common alteration of the regulation of the shikimate pathway. Contrary to glyphosate, the exogenous quinate supplied was probably incorporated into the main trunk from the branch pathway and accumulated in the final products, such as lignin, concomitant with a decrease in the amount of DAHPS protein.
  • Thumbnail Image
    PublicationOpen Access
    Enhancement of glyphosate efficacy on Amaranthus palmeri by exogenous quinate application
    (Elsevier, 2019) Zulet González, Ainhoa; Fernández Escalada, Manuel; Zabalza Aznárez, Ana; Royuela Hernando, Mercedes; Institute for Multidisciplinary Research in Applied Biology - IMAB; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
    Glyphosate is a widely used herbicide targeting the enzyme 5-enolpyruvylshikimate 3-phosphate synthase (EPSPS) in the aromatic amino acid biosynthesis pathway (shikimate pathway) and provoking accumulation of quinate, a secondary metabolite synthesized through a side branch of this pathway. The objective of this work was to evaluate whether the efficacy of glyphosate activity in Amaranthus palmeri is enhanced by quinate application one day after herbicide treatment. To this end, one glyphosate-sensitive and one glyphosate-resistant (due to EPSPS gene amplification) population of A. palmeri were used. The 3- day time course study of the quinate treatment alone showed quinate, Tyr and Phe accumulation in both populations. When the herbicide was applied alone at 0.25× the recommended dose, no phytotoxicity or glyphosate effects were detected in the sensitive population 3 days after treatment, but the combined treatment with quinate was lethal, and markers of herbicide activity at the amino acid level could be detected. In the resistant population, an important metabolic perturbation in the flux of the shikimate pathway was detected in the combined treatment. These results raise the possibility of the joint application of quinate and glyphosate to enhance glyphosate efficacy while lowering doses in the sensitive population.
  • Thumbnail Image
    PublicationOpen Access
    Efecto del glifosato y de diferentes intermediarios metabólicos en la regulación de la ruta del siquimato
    (Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2017) Zulet González, Ainhoa; Fernández Escalada, Manuel; Gil Monreal, Miriam; Zabalza Aznárez, Ana; Royuela Hernando, Mercedes; Ciencias del Medio Natural; Natura Ingurunearen Zientziak; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
    En este estudio se han abordado los mecanismos de regulación de la ruta del siquimato en la biosíntesis de los aminoácidos aromáticos. Para ello se han comparado el contenido de siquimato y de los enzimas EPSPS (5-enolpiruvilsiquimato- 3-fosfato sintasa) y DAHPS (3-Deoxi-D-arabino-heptulosonato-7-fosfato sintasa, enzima de entrada a la ruta) en hojas de dos poblaciones de Amaranthus palmeri (una sensible y otra resistente al glifosato) incubadas con glifosato y/o con diferentes intermediarios de la ruta (siquimato, quinato, fosfoenolpiruvato, y aminoácidos aromáticos). En ambas poblaciones se dieron similares efectos regulatorios de los intermediarios, evidenciando que la sobreexpresión de EPSPS no modifica de manera significativa la regulación general de la ruta. El enzima DAHPS se confirma como enzima clave en la regulación y en la respuesta al glifosato; su síntesis es inhibida por los productos finales de la ruta y por el quinato, y su regulación puede explicar la acumulación de siquimato tras la aplicación de glifosato.