表油菜素内酯对黄瓜子叶过氧化物酶活性和可溶性蛋白含量的影响

０．５ｍｇ／Ｌ的表油菜素内酯（ｅｐｉ－ＢＲ）能显著地促进黄瓜子叶叶绿素ａ、叶绿素ｂ的含量和叶绿素ａ／叶绿素ｂ比值的下降，表明ｅｎｉ－ＢＲ能促进子叶的衰老。从过氧化物酶（ＰＯＤ）的活性测定及同工酶谱发现ｅｐｉ－ＢＲ可提高其活性，暗示它可能通过提高子叶ＰＯＤ的活性而加速子叶叶绿素的降解。另一方面，ｅｐｉ－ＢＲ促进子时可溶性蛋白含量的下降，其中主要是ＲｕＢＰ羧化酶含量的下降，同时，ｅｐｉ－ＢＲ引起子叶游离氨基酸的累积。

Effect of epi-BR on Activity of Peroxidase and Soluble Protein Content of Cucumber Cotyledon

It is shown that epi-brassinolide (epi-BR, 0. 5mg/L), a new synthetic brassinolide, significantly reduced the content of chlorophyll a, chlorophyll b in cucumber cotyledons (Figs. 1, 2 )and the ratio of chlorophyll a/ chlorophyll b (Fig. 3 ). Furhter studies (Figs. 4, 5) showed that in the cotyledons epi-BR increased the activity of peroxidsse (POD), which is involved in the breakdown of the chlorophyll. It is suggested that epi-BR promotes the degradation of chlorophyll in cucumber cotyledons through increasing the activity of POD. In addition, epi-BR decreased the content of soluble protein in cucumber cotyledons (mainly the RuBPcase) (Fial. 6, 7) and caused the accumulation of free amino acids (Fig. 8). All of these effects of epiBR on cucumber cotyledons indicates that epi-BR accelerated the senescence of cucumber cotyledons.