Antioxidant System of Scutellum During Germination and Early Growth of Maize Seedlings

Maize is among the world’s three most important cereals because it is used for human consumption and agricultural feed. The embryo in monocotyledons contains a cotyledon that is the scutellum, which in Chalqueño maize constitutes approximately 80% of the embryo’s mass. The activation of metabolism during germination is accompanied by the production of reactive oxygen species, which must be maintained at a low level to avoid damage. Little is known about the oxidative state of the scutellum, but it is important to understand the control of oxidative stress during the final phase of germination and the embryo–seedling transition. Among the enzymes involved are class III peroxidase (POX), catalase (CAT), and superoxide dismutase (SOD), which were observed in the scutella of isolated imbibed embryos between 0 and 36 h. The activity of SOD fluctuated over a baseline value. The activity of class III POX was greater than that of CAT, showing differences between them in germination and postgermination. The activities of CAT and POX increased during germination (0 to 18 h), stabilized towards the final phase of germination (18 to 24 h), and then increased again in postgermination (24 to 36 h). The POX activity is a biochemical marker of the scutellum metabolism and marks the transition from germination to the embryo–seedling transition.