title: Oxidative stress and phytochelatin characterisation in bread wheat exposed to cadmium excess.
abstract: In this work, we first investigated if the bread wheat (Triticum aestivum L.) cv. Albimonte can be defined as "shoot cadmium excluder"--by comparing the cadmium (Cd) content in leaves and roots and by calculating the shoot-to-root Cd concentration ratio. Furthermore, we evaluated if the exposure to Cd excess could generate oxidative stress in leaves and roots of this cv., in terms of hydrogen peroxide (H(2)O(2)) accumulation, NAD(P)H oxidation rate, and variations in reduced glutathione (GSH) content and peroxidase (POD, EC 1.11.1.7) activity. Finally, we surveyed possible quali- quantitative differences in thiol-peptide compound pattern between roots and leaves, in order to verify whether phytochelatins (PCs) and related thiol-peptides could contribute in limiting the Cd-induced oxidative stress. Unambiguous characterisation of PCs and related forms present in the root samples was obtained by electrospray ionisation mass spectrometry (ESI-MS) and ESI-tandem MS (ESI-MS/MS). Our results indicate that in leaves the stress generated by the low accumulation of Cd (due to a moderate translocation in planta) seems to be counteracted by the antioxidant response and by the PC biosynthesis. On the contrary, in roots, in spite of the elevated presence of PCs and related thiol-peptide-compounds, the excess of Cd causes a decline in the antioxidant protection of the organ, with the consequent generation of considerable amounts of H(2)O(2), a direct agent of oxidative stress.
authors.affiliation: Dipartimento di Chimica e Biotecnologie Agrarie, Università di Pisa, via del Borghetto 80, 56124 Pisa, Italy.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Ranieri
authors.forename: Antonella
authors.initials: A
authors.lastname: Castagna
authors.forename: Francesca
authors.initials: F
authors.lastname: Scebba
authors.forename: Maria
authors.initials: M
authors.lastname: Careri
authors.forename: Ingrid
authors.initials: I
authors.lastname: Zagnoni
authors.forename: Giovanni
authors.initials: G
authors.lastname: Predieri
authors.forename: Massimo
authors.initials: M
authors.lastname: Pagliari
authors.forename: Luigi Sanità
authors.initials: LS
authors.lastname: di Toppi
mesh_terms: D002104:Cadmium / Q000633:toxicity*; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D005978:Glutathione / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D013058:Mass Spectrometry; D008667:Metalloproteins / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology*; D009195:Peroxidase / Q000378:metabolism; D054811:Phytochelatins; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism*; D014908:Triticum / Q000187:drug effects / Q000378:metabolism*
chemical_list: D008667:Metalloproteins; D002104:Cadmium; D009249:NADP; D054811:Phytochelatins; D006861:Hydrogen Peroxide; D009195:Peroxidase; D005978:Glutathione