24-表油菜素内酯对低氧胁迫下黄瓜根系抗氧化系统及无氧呼吸酶活性的影响

Effects of 24-Epibrassinolide on Antioxidant System and Anaerobic Respiratory Enzyme Activities in Cucumber Roots under Hypoxia Stress

用营养液水培,研究了根际低氧胁迫下24-表油菜素内酯(EBR)对2个抗低氧能力不同的黄瓜品种根系中抗氧化系统及无氧呼吸酶活性的影响。结果表明,在低氧胁迫下,EBR处理显著提高了低氧胁迫下2品种黄瓜幼苗根系SOD、POD及ADH活性,降低了O2-·、H2O2和MDA含量、LDH活性及‘中农八号’根系PDC活性,而对‘绿霸春四号’根系PDC及2个品种CAT活性无明显影响,表明外源EBR处理通过促进低氧胁迫下根系中抗氧化酶和ADH活性的提高,降低LDH活性及ROS含量,增强植株抗低氧胁迫的能力。

Seedlings of a hypoxia-resistant cultivar, Ltibachun No.4, and a hypoxia-sensitive cultivar, Zhongnong No.8, were applied by feeding roots. The effects of exogenous 24-epibrassinolide （EBR） on lipid peroxidation, activities of major antioxidant enzymes and anaerobic respiratory enzymes and their time courses were investigated in cucumber seedling roots under hypoxia stress. Root growth was significantly inhibited under hypoxia stress, which was improved by exogenous EBR application （Figs. 1, 2）. （O2·^- and H2O2 level and lipid peroxidation were significantly increased in the roots upon exposure to hypoxia stress, which were inhibited by exogenous EBR application （Fig.3）. EBR treatment increased SOD and POD activities under hypoxia stress （Fig.4）. Hypoxia enhanced the activities of lactate dehydrogenase （LDH）,alcohol dehydrogenase （ADH） and pyruvate decarboxylase （PDC） whereas EBR treatment significantly increased ADH activity, but decreased LDH activity （Fig.5）. There was no significant difference in CAT and PDC activities between the hypoxia stress treatment and ＂hypoxia＋EBR＂ treatment （Figs.4, 5）. From the results obtained in this work it can be concluded that oxidative damage on seedling roots by hypoxia stress can be considerably alleviated, and alcohol fermentation can be enhanced by EBR treatment.