INVESTIGADORES
MAIALE Santiago Javier
congresos y reuniones científicas
Título:
Polyamine oxidase activity contributes to uphold maize leaf elongation under saline stress
Autor/es:
RODRÍGUEZ ANDRES; MAIALE SANTIAGO; MENÉNDEZ ANA; RUIZ OSCAR
Lugar:
Rosario, Pcia. Santa Fe
Reunión:
Congreso; 13 Reunion Latinoamericana y27 RAFV; 2008
Resumen:
The investigation focused on the role of the production of apoplastic reactive oxygen species (aROS) by polyamines (PAs) oxidation on leaf growth of maize plants grown under salinity. Results: Levels of apoplastic PAs (aPAs), spermidine (Spd), and spermine (Spm) increased due to salt treatment, particularly in the elongation zone (EZ) of salinized leaf blade. Amine oxidases (AOs) were present in the EZ and maturation zones (MZ) and no difference was observed in the total AOs levels in vivo under salt stress. Polyamine oxidase (PAO) was the main AO activity present in the apoplast, whereas salinity raised PAO activity in the EZ probably because of the simultaneous rise in aPAs concentrations. The presence of reduced superoxide radical (·O2-) amounts in salt-treated leaves suggested the occurrence of some production mechanism alternative to that of NADPH oxidase (NOX), which results strongly affected by salinity. Analysis of ROS production under saline condition showed that O2- and hydroxyl radical (HO·) were mainly associated with the EZ and produced through aPAs oxidation by PAO. Assays on blade segment elongation showed that Spm stimulated elongation under conditions where NOX activity was reduced by salinity or by the presence of diphenyleneiodonium (DPI). The fact that such stimulation was reversed by the addition of PAO inhibitor 1,19-bis-(ethylamine)-5,10,15 triazanonadecane (SL-11061), or ROS scavengers, reinforces this hypothesis. Conclusions: The obtained results indicate that aPAs accumulation under saline stress and their oxidation by PAO may constitute an alternative ROS source to sustain leaf blade growth in salinity