Glutathione half-cell reduction potential and a-tocopherol as viability markers during the prolonged storage of Suaeda maritima seeds

Antioxidants protect seeds from oxidative damage during storage, supporting the maintenance of seed viability and the ability to germinate post-storage. No data on antioxidants during long-term storage are available for the seeds of the halophyte Suaeda maritima. Therefore, changes in lipid-soluble antioxidants in the tocopherol family (a-, ?-, d-tocopherol), were investigated in seeds stored for up to 16 years at 4°C at a seed moisture content of 10–13%, as well as changes in the water-soluble antioxidant glutathione (GSH) and electrolyte leakage. Seed oil content was also measured and determined to be 22%. During the first 3 years of storage, seed viability remained high and the concentration of total tocopherol was stable. Thereafter, both seed viability and a-tocopherol concentration rapidly decreased and electrolyte leakage increased, while ?-tocopherol and d-tocopherol concentrations did not correlate with seed viability. Although the concentrations of neither GSH nor glutathione disulphide (GSSG) alone were correlated with seed viability, the glutathione half-cell reduction potential (EGSSG/2GSH) was strongly correlated with viability throughout storage and increased before the onset of viability loss. Hence, in this species EGSSG/2GSH appeared to be an ‘early warning’ system preceding viability loss while a-tocopherol concentration changed concomitantly with viability.