Hegedüs A, Erdei S, Horváth G
Department of Molecular Plant Biology, Faculty of Horticultural Science, Szent István University, P.O. Box 53, H-1518, Budapest, Hungary
Plant Sci. 2001 May;160(6):1085-1093. doi: 10.1016/s0168-9452(01)00330-2.
Cadmium(Cd) stress induced alterations in the activities of several representatives of the enzymatic antioxidant defense system such as guiacol peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were comparatively studied in green and greening barley seedlings that represent two different stages of plant development. Although roots were the main site of Cd accumulation, 1.5-3% of Cd was translocated into leaves and it induced oxidative damage which was indicated by the reduced chlorophyll and increased malondialdehyde content of the leaves. In roots of both types of seedlings exposed to various Cd concentrations, the APX activity was enhanced without any increase in the activity of POD. In leaves, however, elevated activities of both POD and APX could be observed. In roots of green seedlings at high concentration of Cd, the APX activity was reduced on the fourth day of culture but no inhibition was found in the POD activity. Leaf CAT which mainly represented the peroxisomal enzyme activity did not display any changes under Cd stress. Our results show that at both developmental stages barley seedlings exhibit a well-defined activity of the enzymatic antioxidant system, which operates differentially in roots and shoots subjected to Cd stress.
在代表植物发育两个不同阶段的绿色和正在变绿的大麦幼苗中，对镉（Cd）胁迫诱导的几种酶促抗氧化防御系统代表酶（如愈创木酚过氧化物酶（POD）、过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX））活性的变化进行了比较研究。虽然根部是镉积累的主要部位，但1.5%-3%的镉会转运到叶片中，并诱导氧化损伤，这表现为叶片叶绿素含量降低和丙二醛含量增加。在暴露于不同镉浓度的两种类型幼苗的根部，APX活性增强，而POD活性没有任何增加。然而，在叶片中，可以观察到POD和APX的活性都升高。在高浓度镉处理下的绿色幼苗根部，培养第四天时APX活性降低，但未发现POD活性受到抑制。主要代表过氧化物酶体酶活性的叶片CAT在镉胁迫下没有表现出任何变化。我们的结果表明，在两个发育阶段，大麦幼苗的酶促抗氧化系统都表现出明确的活性，在受到镉胁迫的根和芽中其运作方式不同。
