title: 2,4-Dichlorophenoxyacetic acid promotes S-nitrosylation and oxidation of actin affecting cytoskeleton and peroxisomal dynamics.
abstract: 2,4-Dichlorophenoxyacetic acid (2,4-D) is a synthetic auxin used as a herbicide to control weeds in agriculture. A high concentration of 2,4-D promotes leaf epinasty and cell death. In this work, the molecular mechanisms involved in the toxicity of this herbicide are studied by analysing in Arabidopsis plants the accumulation of reactive oxygen species (ROS) and nitric oxide (NO), and their effect on cytoskeleton structure and peroxisome dynamics. 2,4-D (23 mM) promotes leaf epinasty, whereas this process was prevented by EDTA, which can reduce ·OH accumulation. The analysis of ROS accumulation by confocal microscopy showed a 2,4-D-dependent increase in both H2O2 and O2·(-), whereas total NO was not affected by the treatment. The herbicide promotes disturbances on the actin cytoskeleton structure as a result of post-translational modification of actin by oxidation and S-nitrosylation, which could disturb actin polymerization, as suggested by the reduction of the F-actin/G-actin ratio. These effects were reduced by EDTA, and the reduction of ROS production in Arabidopsis mutants deficient in xanthine dehydrogenase (Atxdh) gave rise to a reduction in actin oxidation. Also, 2,4-D alters the dynamics of the peroxisome, slowing the speed and shortening the distances by which these organelles are displaced. It is concluded that 2,4-D promotes oxidative and nitrosative stress, causing disturbances in the actin cytoskeleton, thereby affecting the dynamics of peroxisomes and some other organelles such as the mitochondria, with xanthine dehydrogenase being involved in ROS production under these conditions. These structural changes in turn appear to be responsible for the leaf epinasty.
authors.affiliation: Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín, CSIC, Apartado 419, 18080 Granada, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Rodríguez-Serrano
authors.affiliation: Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín, CSIC, Apartado 419, 18080 Granada, Spain.
authors.forename: D M
authors.initials: DM
authors.lastname: Pazmiño
authors.affiliation: School of Biological & Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK.
authors.forename: I
authors.initials: I
authors.lastname: Sparkes
authors.affiliation: School of Biological & Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK.
authors.forename: A
authors.initials: A
authors.lastname: Rochetti
authors.affiliation: School of Biological & Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK.
authors.forename: C
authors.initials: C
authors.lastname: Hawes
authors.affiliation: Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín, CSIC, Apartado 419, 18080 Granada, Spain.
authors.forename: M C
authors.initials: MC
authors.lastname: Romero-Puertas
authors.affiliation: Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín, CSIC, Apartado 419, 18080 Granada, Spain luisamaria.sandalio@eez.csic.es.
authors.forename: L M
authors.initials: LM
authors.lastname: Sandalio
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology*; D008841:Actin Cytoskeleton / Q000187:drug effects* / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D016877:Oxidants / Q000494:pharmacology; D010084:Oxidation-Reduction / Q000187:drug effects; D020675:Peroxisomes / Q000187:drug effects* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D026082:Singlet Oxygen / Q000378:metabolism
chemical_list: D016877:Oxidants; D017382:Reactive Oxygen Species; D026082:Singlet Oxygen; D015084:2,4-Dichlorophenoxyacetic Acid; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D009584:Nitrogen
keywords: 2; 4-D; Actin; ROS; S-nitrosylation; cytoskeleton; nitric oxide; peroxisomes; xanthine dehydrogenase.