title: Changes in ligno-suberization of cell walls of tomato hairy roots produced by salt treatment: the relationship with the release of a basic peroxidase.
abstract: A highly basic peroxidase isoenzyme was shown to be released to the culture medium of tomato (Lycopersicon esculentum) hairy roots grown in Murashige-Skoog (MS) liquid medium when it was supplemented with 100 mM NaCl. In this paper we demonstrate that this enzyme is ionically bound to cell walls and that the release was a consequence of the continuous agitation of the tissue in a high ionic strength medium with salt addition. In order to establish the physiological role of this isoenzyme we partially purified it, and we analysed its kinetic properties as coniferyl alcohol peroxidase. The peroxidase isoenzyme showed a high catalytic efficiency for this substrate, which suggests that it would be associated with the ligno-suberization process. To confirm the involvement of this isoenzyme in that process, we studied the pattern of ligno-suberization of the tissue under different conditions of growth. Our results suggest that this basic peroxidase would be indeed involved in ligno-suberization since its leakage from cell walls, induced by 100 mM NaCl in liquid MS, caused less ligno-suberization of exo and endodermis. On the contrary, more ligno-suberization was seen in cell walls when the hairy roots were grown in a salt-supplemented MS solid medium without contact with it, a condition in which the release of the isoenzyme would be avoided. Thus, through the changes produced by the release of the enzyme from its site of action, we could demonstrate the physiological role of this peroxidase in the processing of root cell walls, being part of control mechanisms of ion and water fluxes through the root.
authors.affiliation: Departamento de Biología Molecular, FCEFQyN, Universidad Nacional de Río Cuarto, Ruta No. 36, Km 601 (CP 5800), Río Cuarto, Córdoba, Argentina. mtalano@exa.unrc.edu.ar
authors.forename: Melina Andrea
authors.initials: MA
authors.lastname: Talano
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Agostini
authors.forename: María I
authors.initials: MI
authors.lastname: Medina
authors.forename: Herminda
authors.initials: H
authors.lastname: Reinoso
authors.forename: María del Carmen
authors.initials: Mdel C
authors.lastname: Tordable
authors.forename: Horacio A
authors.initials: HA
authors.lastname: Tigier
authors.forename: Silvia Milrad
authors.initials: SM
authors.lastname: de Forchetti
mesh_terms: D002473:Cell Wall / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D007527:Isoenzymes / Q000378:metabolism; D018551:Solanum lycopersicum / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology* / Q000378:metabolism; D010544:Peroxidases / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology* / Q000187:drug effects*; D021381:Protein Transport / Q000187:drug effects; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D007527:Isoenzymes; D012965:Sodium Chloride; D010544:Peroxidases