豌豆叶绿体脂氧合酶活性与叶片衰老及膜脂过氧化作用的关系

The Lipoxygenase Activity of Pea Chloroplasts in Relation to Leaf Senescence and Membrane Lipid Peroxidation

豌豆叶绿体脂氧合酶(LOX)活性在连体叶片衰老过程中变化不大。ABA处理离体叶片2d叶绿体LOX活性升高,处理时间延长活性下降。抗氧化剂α-生育酚、谷胱甘肽、没食子酸丙酯抑制豌豆叶绿体LOX活性。脂质过氧化产物丙二醛对豌豆叶绿体LOX和大豆纯LOX-1的活性均有抑制作用,大豆LOX-1能促进离体豌豆叶绿体膜脂过氧化作用。因此,豌豆叶绿体LOX可能参与叶片衰老过程中叶绿体膜结构和功能的改变,又受膜脂过氧化产物的制约。

Chloroplast LOX activity, lipid peroxidation and chlorophyll content in attached pea leaves at different positions and in detached pea leaves treated with ABA were investigated for understanding the relationship between chloroplast LOX activity and leaf-senescence. It was observed that during leaf senescence the MDA content in chloroplasts increased, but the chloroplast LOX activity remained at lower level. The changes of chloroplast LOX activities in senescing detached leaves paralleled with the results obtained from the intact plants except that the transient increased within 2 days after treatment. The results indicated that there was no apparent direct relationship between leaf senescence and the chloroplast LOX activity. The antioxidants α-toco pherol, GSH and propyl gallate inhibited the LOX activity of pea chloroplast. MDA, a product of lipid peroxidation, also inhibited the activity of chloroplast LOX and that of purified soybean LOX-1. Soybean LOX-1 stimulated lipid peroxidation of isolated chloroplasts. MDA and LFP in chloroplasts accumulated with an increase of the concentration of soybean LOX-1. According to these results, a possilble relationship between the LOX activity and lipid peroxidation during leaf senescence was discussed.