Effect of Water Stress on Membrane-lipid Peroxidation and Protective Enzymes in Maize Seedings
Tang Lianshun Li Guangmin (Dept. of Agron. , Hebei Agri. Univ., Baoding, China)
The effects of water stress induced by PEG(MW 1500) solutions on relative water content (RWC), permeability of plasma membrane, membranelipid peroxidation, and activities of protective enzymes: superoxide dismutase (SOD), catalase(CAT), peroxidase(POD) of the different droughtresistant maize cultivars (drought-resistant Ji-Dan No. 24 and drought-sensitive Yan-Dan No. 4) were studied. The results showed that under-0.75 MPa PEG and -1.25 MPa PEG rapid water stress, RWC decreased while permeability of plasma membrane, malondialdehyde (MDA) content, and activlties of SOD, CAT, POD increased. But under -2.00 MPa PEG rapid water stress, RWC decreased rapidly, with permeability of plasma membrane, MDA content increasing sharply while activities of SOD and CAT decreased, with POD activities increasing slowly, when the osmotic potential of PEG solutions decreased stepwise to simulate slow speed water stress, RWC, permeability of plasma membrane and MDA content changed sharply, and activities of SOD, CAT and POD increased obviousely before -1.25 MPa PEG treatment, but RWC decreased obviousely, permeability of plasma membrane and MDA content increased sharply with activities of SOD, CAT and POD decreasing after -1.25 MPa PEG treatment. The rates of changes of the above between two cultivars were different. It is suggested that there appears to be a close correlation between the activities of protective enzymes (SOD, CAT, POD), membrane-lipid peroxidation and permeability of plasma membrane under water stress.