The role of polyamines in maize leaf growth under salinity

ANDRES RODRIGUEZ; OSCAR RUIZ; SANTIAGO MAIALE

Mar del PLata, Bs As, Argentina

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2007

The reduction of leaf expansion is one of the primary effects of salt stress. In previous works, we showed that apoplastic reactive oxygen species (ROS) are necessary for leaf extension in maize. Decreased ROS concentration in the elongation zone (EZ) contributes to the reduction in maize leaf growth under salinity. Also, the polyamines (PAs) are low Mr organic polycations, involved in plant growth and development. Apoplastic PAs oxidation produce H2O2 (ROS). The PAs levels increase in plants under salinity. The purpose of this work was to assess the role of PAs in elongation growth in the expanding zone (EZ) of maize leaf blades, subjected to saline stress. Analysis of PAs in EZ segments (EZS) with highest elongation in control and significant difference with salinized plants did not show changes in total PAs. However, the levels of individual PAs changed, being observed lowest and highest level of putrescine and spermine (spm) respectively in salinized EZS, indicating a displacement of status to superior PAs, like spm. Parallelly, in elongation assays, salinized SEZ tried with BE-4-4-4-4, an inhibitor of polyamine oxidase (PAO), catalytic enzyme of spm, reduced elongation in 25%. These preliminary results could indicate that the H2O2 from the spm oxidation in apoplast, contributes to the maize leaf growth under salinity.