title: Differences in Al tolerance between Plantago algarbiensis and P. almogravensis reflect their ability to respond to oxidative stress.
abstract: We evaluated the impact of low pH and aluminum (Al) on the leaves and roots of Plantago almogravensis Franco and Plantago algarbiensis Samp., focusing on energy partitioning in photosystem II, H₂O₂ levels, lipid peroxidation, electrolyte leakage (EL), protein oxidation, total soluble protein content and antioxidant enzyme activities. In both species, Al triggered more changes in oxidative metabolism than low pH alone, particularly in the roots. We found that Al increased the levels of H₂O₂ in P. algarbiensis roots, but reduced the levels of H₂O₂ in P. almogravensis leaves and roots. Neither low pH nor Al affected the spatial heterogeneity of chlorophyll fluorescence, the maximum photochemical efficiency of PSII (Fv/Fm), the actual quantum efficiency of PSII (ϕPSII) or the quantum yields of regulated (ϕNPQ) and nonregulated (ϕNO) energy dissipation, and there was no significant change in total soluble protein content and EL. In P. algarbiensis, Al increased the carbonyl content and the activities of superoxide dismutase (SOD) and catalase (CAT) in the roots, and also CAT, ascorbate peroxidase and guaiacol peroxidase activities in the leaves. In P. almogravensis, Al reduced the level of malondialdehyde in the roots as well as SOD activity in the leaves and roots. We found that P. almogravensis plantlets could manage the oxidative stress caused by low pH and Al, whereas the P. algarbiensis antioxidant system was unable to suppress Al toxicity completely, leading to the accumulation of H₂O₂ and consequential protein oxidation in the roots.
authors.affiliation: IBB/CGB, Faculty of Sciences and Technology, University of Algarve, Campus de Gambelas, Ed. 8, 8005-139, Faro, Portugal.
authors.forename: Neusa
authors.initials: N
authors.lastname: Martins
authors.forename: Maria Leonor
authors.initials: ML
authors.lastname: Osório
authors.forename: Sandra
authors.initials: S
authors.lastname: Gonçalves
authors.forename: Júlio
authors.initials: J
authors.lastname: Osório
authors.forename: Anabela
authors.initials: A
authors.lastname: Romano
mesh_terms: D000535:Aluminum / Q000008:administration & dosage / Q000494:pharmacology*; D000975:Antioxidants / Q000378:metabolism; D060387:Ascorbate Peroxidases / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D004573:Electrolytes / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D015227:Lipid Peroxidation / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects*; D009195:Peroxidase / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D010943:Plantago / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D004573:Electrolytes; D006861:Hydrogen Peroxide; D000535:Aluminum; C121048:guaiacol peroxidase; D060387:Ascorbate Peroxidases; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase