title: Involvement of the ethylene-signalling pathway in sugar-induced tolerance to the herbicide atrazine in Arabidopsis thaliana seedlings.
abstract: Soluble sugars can induce tolerance to otherwise lethal concentrations of the herbicide atrazine in Arabidopsis thaliana seedlings. This sugar-induced tolerance involves modifications of gene expression which are likely to be related to sugar and xenobiotic signal transduction. Since it has been suggested that ethylene- and sugar-signalling pathways may interact, the effects of glucose (Glc) and sucrose (Suc) on seedling growth and tolerance to atrazine were analysed in etr1-1, ein2-1, ein4, and sis1/ctr1-12 ethylene-signalling mutant backgrounds, where key steps of ethylene signal transduction are affected. Both ethylene-insensitive and ethylene-constitutive types of mutants were found to be affected in sugar-induced chlorophyll accumulation and root growth and in sugar-induced tolerance to atrazine. Interactions between ethylene and sugars were thus shown to take place during enhancement of seedling growth by low-to-moderate (up to 80 mM) sugar concentrations. The strong impairment of sugar-induced atrazine tolerance in etr1-1, ein2-1, and ein4 mutants demonstrated that this tolerance required active signalling pathways and could not be ascribed to mere metabolic effects nor to mere growth enhancement. Sugar-induced atrazine tolerance thus seemed to involve activation by sugar and atrazine of hexokinase-independent sugar signalling pathways and of ethylene signalling pathways, resulting in derepression of hexokinase-mediated Glc repression and in induction of protection mechanisms against atrazine injury.
authors.affiliation: Centre National de la Recherche Scientifique, Université de Rennes 1, UMR 6553 ECOBIO, Campus de Beaulieu, bâtiment 14A, F-35042 Rennes Cedex, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Sulmon
authors.forename: Gwenola
authors.initials: G
authors.lastname: Gouesbet
authors.forename: Abdelhak
authors.initials: A
authors.lastname: El Amrani
authors.forename: Ivan
authors.initials: I
authors.lastname: Couée
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000502:physiology*; D001280:Atrazine / Q000494:pharmacology*; D002241:Carbohydrates / Q000494:pharmacology / Q000502:physiology; D004361:Drug Tolerance; D005030:Ethylenes / Q000378:metabolism*; D006540:Herbicides / Q000494:pharmacology; D010788:Photosynthesis / Q000187:drug effects; D036226:Seedlings / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D002241:Carbohydrates; D005030:Ethylenes; D006540:Herbicides; C036216:ethylene; D001280:Atrazine