表油菜素内酯对黄瓜幼苗下胚轴过氧化物酶和IAA氧化酶活性的影响

黄瓜幼苗用0.1～1 ppm表油菜素内酯(epiBR)处理1～3d后,下胚轴中过氧化物酶活性明显低于对照;随着处理浓度的增加和处理时间的延长,与对照之间的差别愈趋增大。当浓度高于1ppm时,过氧化物酶的活性不再继续降低。表油菜素内醋对过氧化物酶活性的这种抑制作用需经约1O h的滞后期。IAA氧化酶的活性变化与过氧化物酶相似,epiBR处理时间愈长酶活性增加愈趋缓慢。 经IAA处理的下胚轴,过氧化物酶和IAA氧化酶的活性变化与对照无明显差异。这提示油菜素内酯与IAA促进生长可能是通过不同的作用方式。

Effects of Epibrassinolide on the Activities of Peroxidase and IAA Oxidase in Hypocotyl of Cucumber Seedlings

It was shown that epibrassinolide (epiBR)played an important role in the elongation of thehypocotyls of light--grown cucumber seedlings.However, the activity of peroxidase wasincreased in the etiolated hypocotyls treatedby epiBR. The decrease of peroxidase activityin green hypocotyls depended upon the epiBRdosage. EpiBR could markedly inhibit theenzyme activity even at 0. 1 ppm. When theconcentration of epiBR was above 1 ppm, the pero-xidase activity almost ceased to reduce. Thechange of IAA oxidase activity was similarto that of peroxidase. But, both activities didnot secm to be affected distinctly when the cucum-ber seedling segments were incubated with IAA.Generally, the effect of epiBR was found after thetreatment 10 hours. It is suggested that the promotion of thegrowth of cucumber hypocotyls by epiBR andIAA may be regulated by different modes.