水分胁迫对玉米幼苗膜脂过氧化及保护酶的影响

PEG模拟水分胁迫过程中,在胁迫强度较轻、胁迫时间较短、胁迫速度缓慢时,玉米幼苗叶片相对含水量 (RWC) 下降较慢,超氧化物歧化酶 (SOD)过氧化氢酶 (CAT)、过氧化物酶 (POD) 活性上升,脂质过氧化作用较轻,膜相对透性增加较小;在胁迫强度较重、胁迫时间较长、胁迫速度较快时,玉米叶片RWC下降较快,SOD、CAT活性下降、脂质过氧化作用加强、膜透性增大。抗旱性不同的两品种在RWC、质膜透性、丙二醛 (MDA) 含量、SOD、CAT、POD活性上存在着明显的差异。这表明水分胁迫过程中,叶片保护酶系统和脂质过氧化作用、膜透性间存在着一定的相互关系。

Effect of Water Stress on Membrane-lipid Peroxidation and Protective Enzymes in Maize Seedings

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.