title: Short-term phytotoxicity in Brassica napus (L.) in response to pre-emergently applied metazachlor: A microcosm study.
abstract: In accordance with realistic application approaches, a short-term 1-factorial experiment was set up to investigate the phytotoxic impact of pre-emergent application of the chloroacetamide herbicide metazachlor on Brassica napus. In addition to morphological parameters, the underlying processes that ultimately determine the extent of herbicide-induced phytotoxicity (i.e., herbicide metabolization and cellular antioxidant defense) were examined. The present study demonstrated that metazachlor provoked fasciation of the leaves closely after emergence, which might be linked to its mode of action whereby cell division is impaired through the inhibition of very long chain fatty acid synthesis. The increased activities of antioxidative enzymes and metabolites in leaf tissue indicated the presence of reactive oxygen species under the influence of metazachlor. This resulted in oxidative damage in the form of membrane lipid peroxidation. Simultaneously, the increased activity of glutathione S-transferase and the shift in glutathione redox state suggested activation of the detoxification metabolism. This occurred, however, at the expense of growth, with a temporary reduction in plant height and weight after application. The results indicated that metazachlor disappeared within 3 mo to 4 mo after application, which resulted in the recovery of the crop. In conclusion, metazachlor induces phytotoxicity in the short term, either directly through its mode of action or indirectly through the induction of oxidative stress, which resulted in a temporary reduction in growth. Environ Toxicol Chem 2017;36:59-70. © 2016 SETAC.
authors.affiliation: Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium.
authors.forename: Hanne
authors.initials: H
authors.lastname: Vercampt
authors.affiliation: Department of Plant Physiology and Biochemistry, Agricultural University of Plovdiv, Plovdiv, Bulgaria.
authors.forename: Lyubka
authors.initials: L
authors.lastname: Koleva
authors.affiliation: Department of Plant Physiology and Biochemistry, Agricultural University of Plovdiv, Plovdiv, Bulgaria.
authors.forename: Andon
authors.initials: A
authors.lastname: Vassilev
authors.affiliation: Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium.
authors.forename: Jaco
authors.initials: J
authors.lastname: Vangronsveld
authors.affiliation: Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium.
authors.forename: Ann
authors.initials: A
authors.lastname: Cuypers
mesh_terms: D000081:Acetamides / Q000378:metabolism / Q000633:toxicity*; D000975:Antioxidants / Q000378:metabolism; D029688:Brassica napus / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005982:Glutathione Transferase / Q000378:metabolism*; D006540:Herbicides / Q000378:metabolism / Q000633:toxicity*; D018384:Oxidative Stress / Q000187:drug effects*; D010860:Pigments, Biological / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors
chemical_list: D000081:Acetamides; D000975:Antioxidants; D006540:Herbicides; D010860:Pigments, Biological; D017382:Reactive Oxygen Species; D005982:Glutathione Transferase; C521990:metazachlor
keywords: Brassica napus; Metazachlor; Phytotoxicity; Stress response; Toxic effect