title: The effects of salt stress cause a diversion of basal metabolism in barley roots: possible different roles for glucose-6-phosphate dehydrogenase isoforms.
abstract: In this study the effects of salt stress and nitrogen assimilation have been investigated in roots of hydroponically-grown barley plants exposed to 150 mM NaCl, in presence or absence of ammonium as the sole nitrogen source. Salt stress determines a diversion of root metabolism towards the synthesis of osmolytes, such as glycine betaine and proline, and increased levels of reduced glutathione. The metabolic changes triggered by salt stress result in a decrease in both activities and protein abundance of key enzymes, namely GOGAT and PEP carboxylase, and in a slight increase in HSP70. These variations would enhance the requirement for reductants supplied by the OPPP, consistently with the observed increase in total G6PDH activity. The involvement and occurrence of the different G6PDH isoforms have been investigated, and the kinetic properties of partially purified cytosolic and plastidial G6PDHs determined. Bioinformatic analyses examining co-expression profiles of G6PDHs in Arabidopsis and barley corroborate the data presented. Moreover, the gene coding for the root P2-G6PDH isoform was fully sequenced; the biochemical properties of the corresponding protein were examined experimentally. The results are discussed in the light of the possible distinct roles and regulation of the different G6PDH isoforms during salt stress in barley roots.
authors.affiliation: Università di Napoli Federico II, Dipartimento di Biologia, Via Cinthia, 6, I-80126 Napoli, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Cardi
authors.affiliation: Università di Napoli Federico II, Dipartimento di Biologia, Via Cinthia, 6, I-80126 Napoli, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Castiglia
authors.affiliation: Università di Napoli Federico II, Dipartimento di Biologia, Via Cinthia, 6, I-80126 Napoli, Italy.
authors.forename: Myriam
authors.initials: M
authors.lastname: Ferrara
authors.affiliation: Università di Napoli Federico II, Dipartimento di Biologia, Via Cinthia, 6, I-80126 Napoli, Italy.
authors.forename: Gea
authors.initials: G
authors.lastname: Guerriero
authors.affiliation: Institute of Biosciences and BioResources - CNR, Via P. Castellino 111, I-80128 Napoli, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Chiurazzi
authors.affiliation: Università di Napoli Federico II, Dipartimento di Biologia, Via Cinthia, 6, I-80126 Napoli, Italy. Electronic address: sergio.esposito@unina.it.
authors.forename: Sergio
authors.initials: S
authors.lastname: Esposito
mesh_terms: D000595:Amino Acid Sequence; D064751:Ammonium Compounds / Q000378:metabolism / Q000494:pharmacology; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D001481:Basal Metabolism / Q000187:drug effects*; D015153:Blotting, Western; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D005954:Glucosephosphate Dehydrogenase / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D005970:Glutamate Synthase / Q000378:metabolism; D050884:HSP72 Heat-Shock Proteins / Q000378:metabolism; D001467:Hordeum / Q000235:genetics / Q000378:metabolism*; D007527:Isoenzymes / Q000145:classification / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D010730:Phosphoenolpyruvate Carboxylase / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D064751:Ammonium Compounds; D050884:HSP72 Heat-Shock Proteins; D007527:Isoenzymes; D010940:Plant Proteins; D012965:Sodium Chloride; D005954:Glucosephosphate Dehydrogenase; D005970:Glutamate Synthase; D010730:Phosphoenolpyruvate Carboxylase
keywords: Abiotic stress; Hordeum vulgare; Oxidative pentose phosphate pathway; Plant roots