Abstract
Two seed lots of <em>Acer saccharinum</em> (recalcitrant), with an initial moisture content of 50% and 55%, were stored at +3<sup>o</sup>C for 6 months. After this time, their viability (measured as germinability) reached 100% and 30%, respectively. In embryo axes and cotyledons extracted from seeds, two major low molecular antioxidants were assayed: ascorbate (ASA and DHA) and glutathione (GSH and GSSG); and activities of enzymes of the ascorbate-glutathione cycle were measured: ascorbate peroxidase (APO) (E.C. 1.11.1.11), monodehydroascorbate reductase (MR) (E.C. 1.6.5.4), dehydroascorbate reductase (DHAR) (E.C. 1.8.5.1), and glutathione reductase (GR) (E.C. 1.6.4.2.). GSH and GSSG contents of embryo axes of stored seeds decreased, as compared to the control (fresh, non-stored seeds), but a larger decrease was observed in seeds with 30% viability. In cotyledons, a particularly high increase in the GSH content in relation to the control was observed in seeds with 100% viability, while the GSSG content was significantly lower in both stored seed lots than in the control. The ASA level was twice as high in seeds with 30% viability as in the control, both in embryo axes and in cotyledons. The activity of enzymes of the ascorbate-glutathione cycle was higher in embryo axes than in cotyledons. In embryo axes of seeds with 100% viability, enzyme activities were slightly lower than in the control, while in those of seeds with 30% viability, their activities were higher than in the control. The observed changes in activities of enzymes of the ascorbate-glutathione cycle and in ascorbate and glutathione levels suggest that the stored seeds of <em>A. saccharinum</em> have an active antioxidant system, which plays an important role in maintaining their viability during storage.
Highlights
Seeds of Acer saccharinum are a classic example of recalcitrant seeds, i.e. they cannot be dried below a relatively high threshold level of moisture content without a substantial decrease in viability
Seeds of A. saccharinum belong to the recalcitrant category
We found that Ascorbic acid (ASA) and DHA content of seeds with 100% viability did not differ significantly from the control, both in embryo axes and in cotyledons (Fig. 2)
Summary
Seeds of Acer saccharinum are a classic example of recalcitrant seeds, i.e. they cannot be dried below a relatively high threshold level of moisture content without a substantial decrease in viability. Its main role is to act as an intracellular redox buffer (Bartosz 1993) It participates in sulphur metabolism, limits and protects cells against effects of oxidative stress, and takes part in detoxification of xenobiotic components (Potters et al 2002). This cycle is observed in chloroplasts (Asada 1992), and in the cytosol, mitochondria and peroxisomes (Potters et al 2002) It involves specific enzymes, such as ascorbate peroxidase (APO), monodehydroascorbate reductase (MR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) (Bowler et al 1992; Foyer et al 1994; Arrigoni 1994; Torres et al 1997; De Gara and Tommasi 1999; de Pinto et al 1999). The active cooperation of enzymes and high levels of low molecular antioxidants may prevent the loss of metabolic balance in cells, maintaining their redox status at a high level In this way, the excessive production of ROS is counteracted by their increased scavenging. The aim of this study was to analyse changes in the activity of the ascorbate-glutathione cycle during storage of A. saccharinum seeds and to assess how these changes can affect the maintenance of seed viability during storage
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
