title: Effects of Cd2+ on K+, Ca2+ and N uptake in two halophytes Sesuvium portulacastrum and Mesembryanthemum crystallinum: consequences on growth.
abstract: One of the limits of Cd2+-phytoextraction is the high toxicity of this metal to plants. Growth restriction, chlorosis and necrosis are usually accompanied with a large disturbance of the uptake of essential elements. This work aims to study the effects of cadmium (Cd2+) on potassium (K+), calcium (Ca2+) and nitrogen (N) acquisition, and their consequences on growth in two halophytes species: Sesuvium portulacastrum and Mesembryanthemum crystallinum. Seedlings were grown for 30 days in split-root conditions. One half of the root system was immersed in complete nutrient solution (Basal medium (B)) supplemented with 100 microM Cd2+, and the other half was immersed in a Cd2+-free medium, containing all nutrients (B/Cd plants) or deprived of potassium ((B-K)/Cd) or calcium ((B-Ca)/Cd) or nitrogen ((B-N)/Cd). Using this approach, we demonstrated that K+ and Ca2+ uptake was impaired in roots exposed to Cd2+. Concerning N, we noticed no indication of uptake inhibition by Cd2+. However, restriction of K+ uptake by roots was compensated by an increase in the K+-use efficiency, so that growth was not inhibited. Calcium uptake was strongly limited by Cd2. This inhibition was accompanied by a reduction in growth of ((B-Ca)/Cd) plants. Thus, we conclude that Cd2+ limits growth of both halophytes through restriction imposed on Ca2+ uptake. We suggest that the increase of Ca2+ availability in soils could improve the growth of both species in the presence of Cd2+. This would be essential for improving their utility for extraction of this metal by from salty contaminated soils.
authors.affiliation: Laboratoire d'Adaptation des Plantes aux Stress Abiotiques, Centre de Biotechnologie, BP 901, Hammam-Lif 2050, Tunisia.
authors.forename: Tahar
authors.initials: T
authors.lastname: Ghnaya
authors.forename: Inès
authors.initials: I
authors.lastname: Slama
authors.forename: Dorsaf
authors.initials: D
authors.lastname: Messedi
authors.forename: Claude
authors.initials: C
authors.lastname: Grignon
authors.forename: Mohamed Habib
authors.initials: MH
authors.lastname: Ghorbel
authors.forename: Chedly
authors.initials: C
authors.lastname: Abdelly
mesh_terms: D035722:Aizoaceae / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D002104:Cadmium / Q000633:toxicity*; D002118:Calcium / Q000378:metabolism*; D035723:Mesembryanthemum / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism
chemical_list: D002104:Cadmium; D009584:Nitrogen; D011188:Potassium; D002118:Calcium