油菜素内酯对低氧胁迫黄瓜幼苗根系线粒体抗氧化系统及其细胞超微结构的影响

Effects of Brassinolide on the Mitochondria Antioxidant System and Cellular Ultrastructure of Cucumber Seedling Roots under Hypoxic Stress

以黄瓜品种‘中农6号’为试材,采用营养液水培,研究了24–表油菜素内酯(EBR)在低氧胁迫下对黄瓜幼苗根系线粒体抗氧化系统及其细胞超微结构的影响。结果表明:低氧胁迫下黄瓜幼苗根系线粒体超氧阴离子(O2x)产生速率、过氧化氢(H2O2)和丙二醛(MDA)含量显著升高,根系活力下降,根尖细胞受到伤害,处理第3天其SOD、POD、CAT酶活性均受到诱导而高于对照,随着处理时间延长至6d时又显著低于对照;而低氧胁迫下在营养液中添加EBR可在较长时间内维持较高的SOD、POD、CAT等抗氧化酶活性,降低产生速率、H2O2和MDA含量,提高根系活力,减轻根尖细胞受伤程度。可见油菜素内酯对缓解低氧胁迫对黄瓜幼苗根系线粒体抗氧化系统及其超微结构的影响均有良好的效应,可有效缓解低氧胁迫造成的伤害。

A hydroponic experiment was conducted to investigate the effects of exogenous 24-epibrassinolide（EBR）on the mitochondria antioxidant system and cellular ultrastructure in seedlings roots of cucumber（Cucumis sativus L.‘Zhongnong 6’）under hypoxic stress. Under the stress,the superoxide anion（）production rate,contents of hydrogen peroxide（H2O2）and malondialdehyde（MDA） were significantly enhanced,while the root activity was decreased,and the root tip cells were damaged. Compared with the control,the activities of SOD,POD and CAT were induced and were higher at 3 d, but significantly decreased at 6 d by hypoxic stress. However,EBR treatment could keep higher activities of SOD,POD and CAT for a longer time,reduce the generation of ,H2O2 and MDA contents,increasethe root activity,and release the damage of root tip cells. The results suggested that exogenous EBR could play a positive role in regulating the mitochondria antioxidant system and keeping cellular ultrastructure of cucumber seedling roots,and alleviate the damage of hypoxic stress.