ALTERATIONS IN LIPID-COMPOSITION, LIPID-PEROXIDATION AND ANTIOXIDATIVE PROTECTION DURING SENESCENCE IN DROUGHT-STRESSED PLANTS AND NON-DROUGHT STRESSED PLANTS OF PISUM-SATIVUM

Pea (Pisum sativum) plants were deprived of water for successive perio ds. The aging process in control plants was followed simultaneously. L eaves were sampled from plants of different age. The lipid content and composition, lipid peroxidation and activities of enzymes implicated in anti-oxidative defence, superoxide dismutase and glutathione reduct ase were analysed. The drought treatment caused the senescence to star t earlier and being more rapid. An increase in the activities of super oxide dismutase and glutathione reductase was found at the onset of se nescence, followed by a decrease at advanced senescence. The polar acy l lipids decreased and the neutral acyl lipids increased during senesc ence in both treatments. The drought stressed and non-drought stressed plants showed a similar pattern of changes during senescence, though of different magnitude and rate. However, there was a relatively highe r proportion of neutral lipids in the leaves of drought stressed plant s compared to non-drought stressed plants, accompanied by a lower leve l of lipid peroxidation, which might indicate an inhibition in the deg radation of neutral lipids.