The production and role of reactive oxygen species (ROS) in the expanding zone of maize (Zea mays) leaf blades were investigated. ROS release along the leaf blade was evaluated by embedding intact seedlings in 2′,7′-dichlorofluorescein-containing agar and examining the distribution of 2′,7′-dichlorofluorescein fluorescence along leaf 4, 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 were used to assess the role of ROS in leaf elongation. The distribution of cerium perhydroxide deposits in electron micrographs indicated hydrogen peroxide (H₂O₂) presence in the apoplast. 2′,7′-Dichlorofluorescein 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. Segments from the elongation zone 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 H₂O₂ is necessary for leaf elongation, but it could not be distinguished whether H₂O₂, or other ROS, are the actual active agents.

Drought inhibits cell division and expansion in the maize leaf growth zone by reducing antioxidant levels and increases photosynthetic capacity to allow for enh

Water loss from roots back into drying soil is a problem of practical importance in plants growing under conditions of very low substrate water pote

The Poaceae is one of the most important Angiosperm families, in terms of morphological diversity, ecology and economic importance. Species within this family show a very wide variation in terms of salinity tolerance. Salt secretion through salt glands plays a significant role in regulating ion balance, contributing to salinity tolerance. This review focuses on salt glands in the Poaceae family and their role in the salinity tolerance. In Poaceae microhairs have been observed in all subfamilies, except Pooideae, but functioning salt glands are reported only in genera belonging to the Chloridoideae subfamily. Structural, ultrastructural and physiological features of salt glands are summarized and discussed and the use of salt glands as potential target features for improving salt tolerance of crops is considered.