title: A multiple-level study of metal tolerance in Salix fragilis and Salix aurita clones.
abstract: The response of two willow clones (Salix fragilis (Sf) and Salix aurita (Sa)) to the presence of metals (Zn, Cu, Cd, Ni) was studied. Rooted cuttings were planted in control and contaminated soil. After 100days, different parameters (biomass, chlorophyll fluorescence (Fv/Fm), pigment and sugar concentrations, electrolyte leakage and proteome-level changes) were analyzed. The growth of Sa was not influenced by metals whereas Sf produced significantly less biomass when exposed to the pollutants. Furthermore, although Sa did not show a growth reduction in the presence of metals, the overall view of the physiological results among others the changes in the accumulation of sugars and pigments indicated that metals had a more severe impact on this clone. The response at the proteome level confirmed these observations. The growth reduction and the proteomic changes in Sf indicate that this clone adjusts its metabolism to maintain cellular homeostasis. Sa on the contrary maintains growth but the physiological and proteomics data suggests that this can only be done at the cost of cellular deregulation. Therefore high biomass is not linked with a good tolerance strategy. In a long-term study the survival of Sa might be compromised making it a poorer candidate for phytoremediation efforts.
  
  
  CONCLUSIONS
  In the last centuries human activity has resulted in the dispersal of heavy metals with potential phytotoxic effects over large areas. The increased knowledge of the responses of Salix-species, a group of trees with potential as biomass producer but also as phytoremediation agent, when growing on metal-polluted substrate provided by this study has the potential to help in the improved selection of clones with more or less potential for these aims. Contrary to most studies the trees in the current study were exposed to a mixture of metals, thereby facing a closer resemblance to the situation on soils polluted by human activity. Whereas many papers focused on the two main phenotypic characteristics (biomass and accumulation), fewer papers studied proteomic and physiological parameters which allow to have a global view of the tolerance of probable willow candidates for phytoremediation purposes. Our data demonstrates that higher biomass production in presence of metals is not necessarily linked with higher tolerance whereas growth reduction might indicate longer long-term tolerance. In the long term and in the purpose of a future use in phytoremediation, the survival of this high producer clone could be compromised.
authors: Soil and Water Systems Unit, Gembloux Agro-Bio Tech, University of Liège, 2, Passage des Déportés, B-5030 Gembloux, Belgium. Electronic address: aevlard@gmail.com.
authors: Aricia
authors: A
authors: Evlard
authors: Centre de Recherche Public - Gabriel Lippmann, Department Environment Agrobiotechnologies, 41, Rue du Brill, L-4422 Belvaux, Luxembourg. Electronic address: sergeant@lippmann.lu.
authors: Kjell
authors: K
authors: Sergeant
authors: Centre de Recherche Public - Gabriel Lippmann, Department Environment Agrobiotechnologies, 41, Rue du Brill, L-4422 Belvaux, Luxembourg. Electronic address: printz@lippmann.lu.
authors: Bruno
authors: B
authors: Printz
authors: Centre de Recherche Public - Gabriel Lippmann, Department Environment Agrobiotechnologies, 41, Rue du Brill, L-4422 Belvaux, Luxembourg. Electronic address: guignard@lippmann.lu.
authors: Cédric
authors: C
authors: Guignard
authors: Centre de Recherche Public - Gabriel Lippmann, Department Environment Agrobiotechnologies, 41, Rue du Brill, L-4422 Belvaux, Luxembourg. Electronic address: renaut@lippmann.lu.
authors: Jenny
authors: J
authors: Renaut
authors: Soil and Water Systems Unit, Gembloux Agro-Bio Tech, University of Liège, 2, Passage des Déportés, B-5030 Gembloux, Belgium. Electronic address: Bruno.Campanella@ulg.ac.be.
authors: Bruno
authors: B
authors: Campanella
authors: Soil and Water Systems Unit, Gembloux Agro-Bio Tech, University of Liège, 2, Passage des Déportés, B-5030 Gembloux, Belgium. Electronic address: roger.paul@ulg.ac.be.
authors: Roger
authors: R
authors: Paul
authors: Centre de Recherche Public - Gabriel Lippmann, Department Environment Agrobiotechnologies, 41, Rue du Brill, L-4422 Belvaux, Luxembourg. Electronic address: hausman@lippmann.lu.
authors: Jean-Francois
authors: JF
authors: Hausman
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D001673:Biodegradation, Environmental; D018533:Biomass; D002734:Chlorophyll / Q000378:metabolism; D002999:Clone Cells; D005453:Fluorescence; D008670:Metals / Q000633:toxicity*; D018517:Plant Roots / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D040901:Proteomics; D032108:Salix / Q000737:chemistry / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012989:Soil Pollutants / Q000633:toxicity*
chemical_list: D008670:Metals; D012989:Soil Pollutants; D002734:Chlorophyll
keywords: Abiotic stress; Fluorescence; Metal trace elements; Pigment; Proteomics; Willow