Changes in Superoxide Dismutase, Catalase and Glutathione Reductase Activities in Sunflower Seeds during Accelerated Ageing and Subsequent Priming

Abstract

Sunflower (Helianthus annuus L.) seeds progressively lost their germination ability during accelerated ageing. Seed deterioration was associated with an increase in malondialdehyde (MDA) and conjugated diene contents, suggesting that lipid peroxidation was involved in loss of seed viability. Accelerated ageing also resulted in a decrease in the activity of the detoxifying enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR), SOD activity being the least affected.

The initial germination ability of aged seeds was progressively restored by a subsequent osmopriming with a polyethylene glycol-6000 solution (−2 MPa). This treatment resulted in a decrease in lipid peroxidation, estimated by MDA and conjugated diene contents. It was also associated with a progressive increase in SOD, CAT and GR activities, which reached levels similar to those found in unaged seeds. Our results clearly demonstrate that sunflower seed deterioration during accelerated ageing is closely related to a decrease in the activities of detoxifying enzymes and to an increase in lipid peroxidation. The reversibility of these biochemical events during osmopriming suggests that the cell detoxifying system, by preventing accumulation of toxic forms of oxygen, might play a key role in seed resistance to deterioration.