title: Cadmium accumulation and strategies to avoid its toxicity in roots of the citrus rootstock Citrumelo.
abstract: In order to assess implications of Cd-induced oxidative stress in roots of the citrus rootstock Citrumelo, seedlings were hydroponically exposed to two relatively realistic Cd concentrations during 7 days. Our results showed that increasing Cd concentrations in external solution were associated with higher Cd accumulations in roots. At 5μM Cd the accumulation of Cd in roots was over 70-f higher than in aerial part (stem+leaves). Malondialdehyde (MDA), superoxide radical (O(2)(*-)), hydrogen peroxide (H(2)O(2)) and lipoxygenase activity (LOX) increased in Cd-exposed roots, suggesting a metal-induced oxidative stress. The Cd treatment enhanced the activity of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and guaiacol-type peroxidase (G-POD), as well as the content of secondary metabolites i.e. soluble phenolics (SPs) and lignin. Histochemical analyses of roots showed that Cd, H(2)O(2), (O(2)(*-)), lignin and G-POD displayed a similar location pattern. Almost all analyzed parameters showed a similar dynamic tendency with increases under 5μM Cd followed by decreases under 10μM Cd, suggesting that a complex coordinated Cd-defensive mechanism is operating in Citrumelo roots exposed to environmental realistic Cd concentrations.
authors.affiliation: Instituto de Ecología, Fundación Miguel Lillo, Miguel Lillo 251, CP 4000, Tucumán, Argentina.
authors.forename: Griselda
authors.initials: G
authors.lastname: Podazza
authors.forename: Marta
authors.initials: M
authors.lastname: Arias
authors.forename: Fernando E
authors.initials: FE
authors.lastname: Prado
mesh_terms: D002104:Cadmium / Q000378:metabolism / Q000633:toxicity; D002374:Catalase / Q000378:metabolism; D002957:Citrus / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D018384:Oxidative Stress; D009195:Peroxidase / Q000378:metabolism; D010636:Phenols / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D018547:Plant Stems / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D012989:Soil Pollutants / Q000378:metabolism / Q000633:toxicity*; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism
chemical_list: D010636:Phenols; D012989:Soil Pollutants; D002104:Cadmium; D013481:Superoxides; D008315:Malondialdehyde; D006861:Hydrogen Peroxide; C121048:guaiacol peroxidase; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase