title: Pb-induced responses in Zygophyllum fabago plants are organ-dependent and modulated by salicylic acid.
abstract: Zygophyllum fabago is a promising species for restoring heavy metal (HM) polluted soils, although the mechanisms involved in HM tolerance in this non-model plant remain largely unknown. This paper analyses the extent to which redox-active compounds and enzymatic antioxidants in roots, stems and leaves are responsible for Pb tolerance in a metallicolous ecotype of Z. fabago and the possible influence of salicylic acid (SA) pretreatment (24 h, 0.5 mM SA) in the response to Pb stress. SA pretreatment reduced both the accumulation of Pb in roots and even more so the concentration of Pb in aerial parts of the plants, although a similar drop in the content of chlorophylls and in the maximum quantum yield of photosystem II was observed in both Pb- and SA-Pb-treated plants. Pb increased the endogenous free SA levels in all organs and this response was enhanced in root tissues upon SA pretreatment. Generally, Pb induced a reduction in catalase, ascorbate peroxidase and glutathione reductase specific activities, whereas dehydroascorbate reductase was increased in all organs of control plants. SA pretreatment enhanced the Pb-induced H2O2 accumulation in roots by up-regulating Fe-superoxide dismutase isoenzymes. Under Pb stress, the GSH redox ratio remained highly reduced in all organs while the ascorbic acid redox ratio dropped in leaf tissues where a rise in lipid peroxidation products and electrolyte leakage was observed. Finally, an organ-dependent accumulation of proline and β-carboline alkaloids was found, suggesting these nitrogen-redox-active compounds could play a role in the adaptation strategies of this species to Pb stress.
authors.affiliation: Department of Agricultural Science and Technology, Universidad Politécnica de Cartagena, Paseo Alfonso XIII 48, 30203 Cartagena, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: López-Orenes
authors.affiliation: Department of Agricultural Science and Technology, Universidad Politécnica de Cartagena, Paseo Alfonso XIII 48, 30203 Cartagena, Spain.
authors.forename: Ascensión
authors.initials: A
authors.lastname: Martínez-Pérez
authors.affiliation: Department of Agricultural Science and Technology, Universidad Politécnica de Cartagena, Paseo Alfonso XIII 48, 30203 Cartagena, Spain.
authors.forename: Antonio A
authors.initials: AA
authors.lastname: Calderón
authors.affiliation: Department of Agricultural Science and Technology, Universidad Politécnica de Cartagena, Paseo Alfonso XIII 48, 30203 Cartagena, Spain. Electronic address: mangeles.ferrer@upct.es.
authors.forename: María A
authors.initials: MA
authors.lastname: Ferrer
mesh_terms: D006861:Hydrogen Peroxide / Q000378:metabolism; D007854:Lead / Q000633:toxicity*; D020156:Salicylic Acid / Q000494:pharmacology*; D012989:Soil Pollutants / Q000633:toxicity*; D032445:Zygophyllum / Q000187:drug effects* / Q000378:metabolism
chemical_list: D012989:Soil Pollutants; D007854:Lead; D006861:Hydrogen Peroxide; D020156:Salicylic Acid
keywords: Alkaloids; Cellular redox state; Lead stress; Proline; Salicylic acid; Zygophyllum fabago