Free-radical-induced lipid peroxidation in seeds

From the practical standpoint, it is desirable to prolong the shelf life of seeds not only under optimum conditions of storage but also under suboptimal conditions. Production of radicals and their intermediates during storage of low or high lipid-containing seeds, and their relationship to seed aging is poorly understood. Reactions involving free radicals are an inherent feature of seed deterioration. Evidence suggests that degradation of lipids in deteriorating seeds, releasing free fatty acids, initiates oxidative deterioration by providing substrate for lipoxygenase. Membranes are primary targets of free radical attack. Recent studies showed that low-vigor embryos contained significantly higher levels of free radicals than high-vigor ones, while embryos from medium-vigor lots showed intermediate values. Pretreatment of seeds with an appropriate ratio of vitamin C to vitamin E may result in a synergistic defense response to oxidative lipid damage and, thus, may prevent seed deterioration to some extent. Indeed, knowledge of identification, isolation, cloning, and plant transformation of genes controlling unsaturated fatty acid metabolism in relation to lipid peroxidation (seed aging) will be an added advantage for post-harvest seed storage technology.