INVESTIGADORES
RODRIGUEZ andres Alberto
congresos y reuniones científicas
Título:
Reactive Oxygen Species in The Elongation Zone of Maize Leaves are Necessary for Leaf Extension
Autor/es:
ANDRES RODRIGUEZ; KARINA GRUNBERG; EDITH TALEISNIK
Lugar:
Punta del Este, Uruguay
Reunión:
Congreso; XI Reunión Latinoamericana de Fisiología Vegetal, XXIV Reunión Argentina de Fisiología Vegetal, I Congreso Uruguayo de Fisiología Vegetal; 2002
Resumen:
The production and role of reactive oxygen species (ROS) in the expanding zone of maize (Zea mays L.) leaf blades were investigated. ROS release along the leaf blade was evaluated by embedding intact seedlings in 2´, 7´-dichlorofluorescin – containing agar and examining the distribution of fluorescence along leaf four, which was exposed by removing the outer leaves before embedding the seedling. Fluorescence was high in the expanding region, becoming practically non-detectable beyond 65 mm from the ligule, indicating high ROS production in the expansion zone. Segments obtained from the elongation zone of leaf 4 (SEZ), were used to assess the role of ROS in leaf elongation. The distribution of cerium perohydroxide deposits in electron micrographs indicated H2O2 presence in the apoplast. Fluorescence and apoplastic H2O2 accumulation were inhibited with diphenyleneiodonium (DPI), which also inhibited O·2- generation, suggesting a flavin containing enzyme activity such as NADPH oxidase was involved in ROS production. SEZ incubated in water grew 8% in 2 h. KI treatments, which scavenged H2O2 but did not inhibit O·2- production, did not modify growth. DPI significantly inhibited segment elongation, and the addition of H2O2 (50 or 500 μM) to the incubation medium partially reverted the inhibition caused by DPI. These results indicate that a certain concentration of ROS is necessary for leaf elongation.