title: Lipids and NADPH-dependent superoxide production in plasma membrane vesicles from roots of wheat grown under copper deficiency or excess.
abstract: The effects of in vivo copper on the lipid composition of root plasma membrane and the activities of membrane-bound enzymes, such as NADPH-dependent oxidases and lipoxygenase, were studied. Plants were grown in hydroponic culture for 11 d without Cu supply or in the presence of 50 microM Cu. Control plants were supplied with 0.3 microM Cu. Growth of roots was severely affected in the 50 microM Cu-grown plants, whereas roots grown in Cu-deficient solution did not show any difference in comparison with the control. The 50 microM Cu concentration caused an increase in the leakage of K(+) ions as well. Excess metal supply resulted in a decrease in the total lipid content of plasma membrane, a higher phospholipid amount and a reduction of steryl lipids (free sterols, steryl glycosides and acylated steryl glycosides). Cu depletion in the growth solution had only a slight effect on the plasma membrane lipid composition. In comparison with the control, only the excess of Cu caused a decrease in the lipid to protein ratio as well as a change in the phospholipid composition, with a lower phosphatidylcholine to phosphatidylethanolamine ratio. The degree of unsaturation of root plasma membranes decreased following the 0 Cu treatment and even more after the 50 microM Cu supply. Plasma membranes of wheat grown under metal deficiency and excess showed increased NADPH-dependent superoxide-producing oxidase activities, whereas membrane-bound lipoxygenase was not increased or activated due to Cu treatments. The consequences of changes in plasma membrane lipid composition and activated oxygen production as a result of Cu treatments are discussed.
authors.affiliation: Dipartimento di Chimica e Biotecnologie Agrarie, Università degli Studi di Pisa, Via del Borghetto, 80, 56124 Pisa, Italy.
authors.forename: M F
authors.initials: MF
authors.lastname: Quartacci
authors.forename: E
authors.initials: E
authors.lastname: Cosi
authors.forename: F
authors.initials: F
authors.lastname: Navari-Izzo
mesh_terms: D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002855:Chromatography, Thin Layer; D003300:Copper / Q000008:administration & dosage / Q000172:deficiency / Q000494:pharmacology*; D005227:Fatty Acids / Q000032:analysis; D017343:Genes, Plant; D066298:In Vitro Techniques; D008055:Lipids / Q000032:analysis / Q000096:biosynthesis*; D008084:Lipoxygenase / Q000378:metabolism; D009249:NADP / Q000096:biosynthesis*; D019255:NADPH Oxidases / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D018517:Plant Roots / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D011188:Potassium / Q000032:analysis; D013481:Superoxides / Q000378:metabolism*; D014908:Triticum / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D008055:Lipids; D013481:Superoxides; D009249:NADP; D003300:Copper; D008084:Lipoxygenase; D019255:NADPH Oxidases; D011188:Potassium; D010100:Oxygen