干旱胁迫对大豆苗期叶片保护酶活性和膜脂过氧化作用的影响

以2个不同耐旱性的大豆品种为试材,研究了干旱胁迫对大豆苗期叶片保护酶活性和膜脂过氧化作用的影响及其与耐旱性的关系。结果表明,随着干旱胁迫的加强,质膜透性和丙二醛(MDA)含量逐渐增加,超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性表现为先升后降的趋势。轻度胁迫下质膜透性和MDA含量增幅较小,重度胁迫时增幅达显著或极显著水平。经相关性分析可知,MDA含量与质膜透性呈极显著正相关;SOD和CAT活性分别在胁迫的第2d和第3d时达到峰值,而后下降,第6d时酶活性明显低于对照;而POD活性在第3、4d时达到峰值,而后下降,第6d时仍略高于对照,维持较高水平。耐旱性品种比不耐旱性品种具有较低的质膜透性和MDA含量,同时具有较高的SOD、CAT和POD活性。

Effects of Drought Stress on Protective Enzymes Activities and Membrane Lipid Peroxidation in Leaves of Soybean Seedlings

The effects of drought stress on the protective enzymes activities and membrane lipid peroxidation in leaves of soybean seedlings and their relations with drought tolerance were studied using two drought-tolerant cultivars.The results showed that under severe drought stress,permeability of plasma membrane and content of malondialdephyde(MDA)increased gradually,and activities of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT)increased first then decreased.Under mild drought stress,permeability of plasma membrane and content of MDA increased a little,while,under severe drought stress,the increasing was significant or very significant.The correlation analysis showed that there was a highly significant positive correlation between content of MDA and permeability of plasma membrane.The activities of SOD and CAT were the highest at the second day and the third day respectively,then decreased,obviously lower than that of the control at the sixth day;but the activity of POD being the highest at the third or fourth day,then decreased,still higher than that of the control at the sixth day,maintaining high level.The drought-tolerant cultivars had lower permeability of plasma membrane and content of MDA than the drought-sensitive,with higher activities of SOD,POD and CAT.