Lipid peroxidation and antioxidant systems of protection against heat shock in pea (Pisum sativum L.) chloroplasts

Heat shock-induced lipid peroxidation (POL) and changes in the antioxidant protective systems were studied in pea (Pisum sativum L.) chloroplasts. The level of POL, as dependent on the balance between pro-and antioxidant systems, changed during plant growth and development. A sharp increase in the content of hydroperoxides and a decrease in the activity of glutathione reductase were observed at the stage of flower bud formation. Some decrease in the activity of antioxidant systems and increase in POL level were characteristic of the reproductive stages. Under hear shock (42 degrees C for 2 h), the balance of prooxidants-antioxidants shifted to POL activation, resulting in an increase in the content: of diene conjugates, hydroxyperoxides, and malonic dialdehyde. Adaptation to temperature stress resulted in the augmentation of both the activity of superoxide dismutase and the content of carotenoids. In another antioxidant system, however, the activity of glutathione reductase and the level of reduced glutathione declined under this stress. The data obtained allowed us to consider the POL and antioxidant protective systems in chloroplasts as a factor in the development of the primary response of plant cells to heat shock.