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 antioxi dant protective systems were studied in pea (Pisum sativum L.) chlorop lasts. The level of POL, as dependent on the balance between pro-and a ntioxidant systems, changed during plant growth and development. A sha rp increase in the content of hydroperoxides and a decrease in the act ivity of glutathione reductase were observed at the stage of flower bu d 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-an tioxidants 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 bot h the activity of superoxide dismutase and the content of carotenoids. In another antioxidant system, however, the activity of glutathione r eductase and the level of reduced glutathione declined under this stre ss. The data obtained allowed us to consider the POL and antioxidant p rotective systems in chloroplasts as a factor in the development of th e primary response of plant cells to heat shock.