小麦叶片衰老过程中CAT和APX活力及其同工酶谱的变化

CHANGES OF ACTIVITIES AND ISOENZYMIC ZYMOGRAM OF CAT AND APX DURING SENESCENCE OF WHEAT LEAVES

小麦叶片在连体自然衰老和离体暗诱导衰老过程中，过氧化氢酶（ＣＡＴ）活力比抗坏血酸过氧化物酶（ＡＰＸ）活力下降得早。当ＣＡＴ活力处于较低水平时，ＡＰＸ仍然维持较高活力，且ＡＰＸ活力与Ｈ２Ｏ２含量呈显著负相关。经同工酶电泳分析，离体叶片暗诱导衰老过程中，ＣＡＴ同工酶带无增减，只是活性改变，而ＡＰＸ同工酶带则有增加。

The activity of ascorbate peroxidase (APX) decreased later than that of catalase (CAT) during the course of senescence of intact and detached wheat leaves. When the activity level of CAT was lower, that of APX still remained higher. The APX activity was negatively correlated with the content of hydrogen peroxide. Furthermore, two additional bands were found on the isozymogram of APX, while the band number of CAT was unchanged during the senescence of detached wheat leaves. All these suggested that APX might play a significant role in scavenging hydrogen peroxide during the middle and late senescence period of wheat leaves.