Vorobets N. Endogenous mechanisms in plant to lead detoxification by the ascorbate-glutathione system participation

3. Object: adaptive mechanisms in plant to lead. It is shown, that the presence of lead ions in concentration 10-3- 10-8 M in medium conduct to changes in metabolic process, increases of malondialdehyde and hydrogen peroxide content. It is established the inhibitory effect of high dose of lead (10-3 M) on glutamate dehydrogenase, glutamine synthetase, aspartate amino transferase and alanine amino transferase. Pool and correlation between violaxanthin cycle pigments change in exceed lead ions level. Perhaps this cycle is implicated in protection against damage by lead. The decrease in water status of the plant takes place in high dose lead medium supplied condition (10-3 M). A high ascorbic acid content during the first stages of germination and growth is a strategy developed in seed of plants to cope with an increased level of reactive oxygen species induced by lead ions. Analysis of enzymes activity proved that the ascorbic acid-glutathione cycle (especially ascorbate peroxidase activity) is stimulated to counteract the injurious effects of lead in sunflower and bean under germination and early growth period. Dehydroascorbate reductase and glutathione reductase contribute to maintaining a high level of ascorbic acid and to avoiding the accumulation of dehydroascorbic acid. Introduction: in educative establishments of medical and biological profile; branch: biology.