title: Polyamine oxidase activity contributes to sustain maize leaf elongation under saline stress.
abstract: The possible involvement of apoplastic reactive oxygen species produced by the oxidation of free polyamines in the leaf growth of salinized maize has been studied here. Salt treatment increased the apoplastic spermine and spermidine levels, mainly in the leaf blade elongation zone. The total activity of polyamine oxidase was up to 20-fold higher than that of the copper-containing amine oxidase. Measurements of H(2)O(2), *O(2)(-), and HO* production in the presence or absence of the polyamine oxidase inhibitors 1,19-bis-(ethylamine)-5,10,15 triazanonadecane and 1,8-diamino-octane suggest that, in salinized plants, the oxidation of free apoplastic polyamines by polyamine oxidase by would be the main source of reactive oxygen species in the elongation zone of maize leaf blades. This effect is probably due to increased substrate availability. Incubation with 200 microM spermine doubled segment elongation, whereas the addition of 1,19-bis-(ethylamine)-5,10,15 triazanonadecane and 1,8-diamino-octane to 200 microM spermine attenuated and reversed the last effect, respectively. Similarly, the addition of MnCl(2) (an *O(2)(-) dismutating agent) or the HO* scavenger sodium benzoate along with spermine, annulled the elongating effect of the polyamine on the salinized segments. As a whole, the results obtained here demonstrated that, under salinity, polyamine oxidase activity provides a significant production of reactive oxygen species in the apoplast which contributes to 25-30% of the maize leaf blade elongation.
authors.affiliation: Unidad de Biotecnología 1, Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús/Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de General San Martín (IIB-INTECH/CONICET-UNSAM), Camino de Circunvalación Laguna, Chascomús, Argentina. andresrodriguez@intech.gov.ar
authors.forename: Andrés Alberto
authors.initials: AA
authors.lastname: Rodríguez
authors.forename: Santiago Javier
authors.initials: SJ
authors.lastname: Maiale
authors.forename: Ana Bernardina
authors.initials: AB
authors.lastname: Menéndez
authors.forename: Oscar Adolfo
authors.initials: OA
authors.lastname: Ruiz
mesh_terms: D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000378:metabolism*; D018515:Plant Leaves / Q000201:enzymology / Q000254:growth & development* / Q000502:physiology; D010940:Plant Proteins / Q000378:metabolism*; D012965:Sodium Chloride / Q000378:metabolism*; D013312:Stress, Physiological; D003313:Zea mays / Q000201:enzymology* / Q000254:growth & development / Q000502:physiology; D000097667:Polyamine Oxidase
chemical_list: D000587:Oxidoreductases Acting on CH-NH Group Donors; D010940:Plant Proteins; D012965:Sodium Chloride; D000097667:Polyamine Oxidase