Loss of seed viability has been associated with deteriorative processes that are partly caused by oxidative damage. The breaking of dormancy, a seed trait that prevents germination in unfavourable seasons, has also been associated with oxidative processes. It is neither clear how much overlap exists between these mechanisms nor is the specific roles played by oxygen and reactive oxygen species.
Morscher et al. study antioxidant profiles in fresh (dormant) or after-ripened (non-dormant) sunflower (Helianthus annuus) embryos subjected to controlled deterioration under ambient or elevated O2, and find that dormancy breaking and viability loss correlate with significant oxidation of the cellular redox environment, assessed via glutathione redox state, changes in antioxidant enzyme activities and protein carbonylation. On the other hand, the lipid environment remains rather stable, even in dead seeds. High O2 concentrations accelerate dormancy alleviation, but surprisingly do not accelerate the rate of viability loss.
This article appears in the special issue ROS and NO Reactions in Plants.