Storage elicits a fast antioxidant enzyme activity in Araucaria angustifolia embryos

Storage of recalcitrant seeds leads to the initiation of subcellular damage or to the initiation of germination process, and both may result in viability loss. This study aimed to elucidate the biochemical basis of embryos survival of Araucaria angustifolia recalcitrant seeds during storage. After harvesting, seeds were stored at ambient conditions (without temperature and humidity control) and in a cold chamber (temperature of 10 ± 3 °C, and relative humidity of 45 ± 5 %). Moisture content, viability, H2O2 content, lipid peroxidation, protein content, and activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), at 0, 15, 45 and 90 days of storage, were evaluated. Seed viability reduced about 40 % during the storage period accompanied by a reduction in soluble protein (about 64 % of reduction) in both storage conditions, and increased lipid peroxidation (about 115 % and 66 % for ambient and cold chamber conditions, respectively). H2O2 content used as a marker of oxidative stress was reduced during the period, possibly controlled by the action of CAT and APX, for which increased activities were observed. The results allowed the identification of seven SOD isoenzymes (one Mn-SOD, five Fe-SOD and one Cu/Zn-SOD), whose activities also increased in response to storage. Some biochemical damage resulting from storage was observed, but viability reduction was not due to failure of enzymatic protection mechanisms.