title: Lead tolerance of water hyacinth (Eichhornia crassipes Mart. - Pontederiaceae) as defined by anatomical and physiological traits.
abstract: This study aimed at verifying the lead tolerance of water hyacinth and at looking at consequent anatomical and physiological modifications. Water hyacinth plants were grown on nutrient solutions with five different lead concentrations: 0.00, 0.50, 1.00, 2.00 and 4.00 mg L-1 by 20 days. Photosynthesis, transpiration, stomatal conductance and the Ci/Ca rate were measured at the end of 15 days of experiment. At the end of the experiment, the anatomical modifications in the roots and leaves, and the activity of antioxidant system enzymes, were evaluated. Photosynthetic and Ci/Ca rates were both increased under all lead treatments. Leaf anatomy did not exhibit any evidence of toxicity effects, but showed modifications of the stomata and in the thickness of the palisade and spongy parenchyma in the presence of lead. Likewise, root anatomy did not exhibit any toxicity effects, but the xylem and phloem exhibited favorable modifications as well as increased apoplastic barriers. All antioxidant system enzymes exhibited increased activity in the leaves, and some modifications in roots, in the presence of lead. It is likely, therefore, that water hyacinth tolerance to lead is related to anatomical and physiological modifications such as increased photosynthesis and enhanced anatomical capacity for CO2 assimilation and water conductance.
authors.affiliation: Universidade Federal de Lavras, Departamento de Biologia, Campus Universitário, Lavras, MG, Brasil.
authors.forename: Fabricio J
authors.initials: FJ
authors.lastname: Pereira
authors.affiliation: Universidade Federal de Lavras, Departamento de Biologia, Campus Universitário, Lavras, MG, Brasil.
authors.forename: Evaristo M de
authors.initials: EM
authors.lastname: Castro
authors.affiliation: Universidade Federal de Lavras, Departamento de Biologia, Campus Universitário, Lavras, MG, Brasil.
authors.forename: Cynthia de
authors.initials: Cd
authors.lastname: Oliveira
authors.affiliation: Universidade Federal de Lavras, Departamento de Biologia, Campus Universitário, Lavras, MG, Brasil.
authors.forename: Marinês F
authors.initials: MF
authors.lastname: Pires
authors.affiliation: Universidade Federal de Lavras, Departamento de Biologia, Campus Universitário, Lavras, MG, Brasil.
authors.forename: Marcio P
authors.initials: MP
authors.lastname: Pereira
authors.affiliation: Universidade Federal de Lavras, Departamento de Ciência do Solo, Campus Universitário, Lavras, MG, Brasil.
authors.forename: Silvio J
authors.initials: SJ
authors.lastname: Ramos
authors.affiliation: Universidade Federal de Lavras, Departamento de Ciência do Solo, Campus Universitário, Lavras, MG, Brasil.
authors.forename: Valdemar
authors.initials: V
authors.lastname: Faquin
mesh_terms: D031806:Eichhornia / Q000033:anatomy & histology / Q000145:classification / Q000187:drug effects* / Q000502:physiology; D007854:Lead / Q000494:pharmacology*; D010788:Photosynthesis / Q000187:drug effects*; D018515:Plant Leaves / Q000166:cytology / Q000187:drug effects; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects
chemical_list: D007854:Lead