表油菜素内酯对绿豆幼叶衰老的促进作用

Enhancement of Senescence by Epibrassinolide in Leaves of Mung Beau Seedling

表油菜素内酯（ｅｐｉＢＲ）０．０５ｍｇ／Ｌ能促进绿豆幼叶的衰老，其叶绿素和蛋白质含量均明显低于对照。绿豆幼叶经ｅｐｉＢＲ处理后，可使过氧化物酶活性明显增加，但同工酶谱无变化；超氧化物歧化酶（ＳＯＤ）和过氧化氢酶（ＣＡＴ）活性随ｅｐｉＢＲ处理时间的延长而降低。ｅｐｉＢＲ能促进丙二醛（ＭＤＡ）含量增加，而其含量与ＳＯＤ和ＣＡＴ活性是显著负相关。

The study showed that epibrassinolide (epiBR) 0. 05 mg/L could stimulate the senescence of light-grown mung bean seedling leaves. The contents of chlorophyll and protein in leaves treated with epiBR decreased more rapidly than those of the control (Fig. 1A, B). The study also revealed that the activity of peroxidase in leaves of mung bean seedling was promoted by epiBR (Fig. 2). The activities of both superoxide dismutase (SOD ) and catalase (CAT) were inhibited by epiBR (Fig. 4A, B),the latter to a greater extent. On the other hand, the level of malonaldehyde (MDA ) markedly increased during the senescence of leaves (Fig. 6 ), and the MDA of leaves showed negative correlation with the activities of SOD and CAT (Fig. 5A,B).These results suggested that activated oxygen may play an importent role in the senescence of plant tissue and be regulated directly or indirectly by epiBR.