title: Response to copper excess in Arabidopsis thaliana: Impact on the root system architecture, hormone distribution, lignin accumulation and mineral profile.
abstract: Growth, in particular reorganization of the root system architecture, mineral homeostasis and root hormone distribution were studied in Arabidopsis thaliana upon copper excess. Five-week-old Arabidopsis plants growing in hydroponics were exposed to different Cu(2+) concentrations (up to 5 muM). Root biomass was more severely inhibited than shoot biomass and Cu was mainly retained in roots. Cu(2+) excess also induced important changes in the ionome. In roots, Mg, Ca, Fe and Zn concentrations increased, whereas K and S decreased. Shoot K, Ca, P, and Mn concentrations decreased upon Cu(2+) exposure. Further, experiments with seedlings vertically grown on agar were carried out to investigate the root architecture changes. Increasing Cu(2+) concentrations (up to 50 muM) reduced the primary root growth and increased the density of short lateral roots. Experiment of split-root system emphasized a local toxicity of Cu(2+) on the root system. Observations of GUS reporter lines suggested changes in auxin and cytokinin accumulations and in mitotic activity within the primary and secondary root tips treated with Cu(2+). At toxic Cu(2+) concentrations (50 muM), these responses were accompanied by higher root apical meristem death. Contrary to previous reports, growth on high Cu(2+) did not induce an ethylene production. Finally lignin deposition was detected in Cu(2+)-treated roots, probably impacting on the translocation of nutrients. The effects on mineral profile, hormonal status, mitotic activity, cell viability and lignin deposition changes on the Cu(2+)-induced reorganization of the root system architecture are discussed.
authors.affiliation: Laboratoire de Physiologie et de Génétique Moléculaire des Plantes, Université Libre de Bruxelles, CP242, boulevard du Triomphe, 1050 Brussels, Belgium.
authors.forename: Hélène
authors.initials: H
authors.lastname: Lequeux
authors.forename: Christian
authors.initials: C
authors.lastname: Hermans
authors.forename: Stanley
authors.initials: S
authors.lastname: Lutts
authors.forename: Nathalie
authors.initials: N
authors.lastname: Verbruggen
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D017360:Arabidopsis / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D018533:Biomass; D002118:Calcium / Q000378:metabolism; D003300:Copper / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D005030:Ethylenes / Q000378:metabolism; D018527:Hydroponics; D007501:Iron / Q000378:metabolism; D008031:Lignin / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism; D008345:Manganese / Q000378:metabolism; D008903:Minerals / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism; D046509:Tissue Culture Techniques; D015032:Zinc / Q000378:metabolism
chemical_list: D005030:Ethylenes; D008903:Minerals; D010937:Plant Growth Regulators; D010758:Phosphorus; D008345:Manganese; D013455:Sulfur; D003300:Copper; D008031:Lignin; C036216:ethylene; D007501:Iron; D008274:Magnesium; D015032:Zinc; D011188:Potassium; D002118:Calcium