title: Effects of lead on the growth, lead accumulation and physiological responses of Pluchea sagittalis.
abstract: This work aimed to study the process of stress adaptation in root and leaves of different developmental stages (apex, middle and basal regions) of Pluchea sagittalis (Lam.) Cabrera plants grown under exposure to five Pb levels (0, 200, 400, 600 and 1000 μM) for 30 days. Pb concentration and content in roots, stems, and leaves of different developmental stages increased with external Pb level. Consumption of nutrient solution, transpiration ratio, leaf fresh weight, leaf area, and shoot length decreased upon addition of Pb treatments. However, dry weight of shoot parts and roots did not decrease upon addition of Pb treatments. Based on index of tolerance, the roots were much more tolerant to Pb than shoots. δ-aminolevulinic acid dehydratase activity was decreased by Pb treatments, whereas carotenoid and chlorophyll concentrations were not affected. Lipid peroxidation and hydrogen peroxide concentration both in roots and leaves increased with increasing Pb levels. Pb treatments increased ascorbate peroxidase activity in all plant parts, while superoxide dismutase activity increased in leaves and did not change in roots. Catalase activity in leaves from the apex shoot was not affected by Pb, but in other plant parts it was increased. Pb toxicity caused increase in non-protein thiol groups concentration in shoot parts, whereas no significant difference was observed in roots. Both root and shoot ascorbic acid concentration increased with increasing Pb level. Therefore, it seems that Pb stress triggered an efficient defense mechanism against oxidative stress in P. sagittalis but its magnitude was depending on the plant organ and of their physiological status. In addition, these results suggest that P. sagittalis is Pb-tolerant. In conclusion, P. sagittalis is able to accumulate on average 6730 and 550 μg Pb g(-1) dry weight, respectively, in the roots and shoot, a physiological trait which may be exploited for the phytoremediation of contaminated soils and waters.
authors.affiliation: Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS 97105-900, Brazil.
authors.forename: Liana Veronica
authors.initials: LV
authors.lastname: Rossato
authors.forename: Fernando Teixeira
authors.initials: FT
authors.lastname: Nicoloso
authors.forename: Júlia Gomes
authors.initials: JG
authors.lastname: Farias
authors.forename: Denise
authors.initials: D
authors.lastname: Cargnelluti
authors.forename: Luciane Almeri
authors.initials: LA
authors.lastname: Tabaldi
authors.forename: Fabiane Goldschmidt
authors.initials: FG
authors.lastname: Antes
authors.forename: Valderi Luiz
authors.initials: VL
authors.lastname: Dressler
authors.forename: Vera Maria
authors.initials: VM
authors.lastname: Morsch
authors.forename: Maria Rosa Chitolina
authors.initials: MR
authors.lastname: Schetinger
mesh_terms: D060387:Ascorbate Peroxidases / Q000187:drug effects / Q000378:metabolism; D001205:Ascorbic Acid / Q000378:metabolism; D019659:Asteraceae / Q000187:drug effects* / Q000254:growth & development; D001673:Biodegradation, Environmental; D002338:Carotenoids / Q000032:analysis / Q000378:metabolism; D002734:Chlorophyll / Q000032:analysis / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D007854:Lead / Q000032:analysis* / Q000493:pharmacokinetics*; D015227:Lipid Peroxidation / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development; D013482:Superoxide Dismutase / Q000187:drug effects / Q000378:metabolism
chemical_list: D002734:Chlorophyll; D007854:Lead; D002338:Carotenoids; D006861:Hydrogen Peroxide; D060387:Ascorbate Peroxidases; D013482:Superoxide Dismutase; D001205:Ascorbic Acid