Kang Yun-Yan, Guo Shi-Rong, Duan Jiu-Ju, Hu Xiao-Hui
College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.
Zhi Wu Sheng Li Yu Fen Zi Sheng Wu Xue Xue Bao. 2006 Oct;32(5):535-42.
Seedlings of a hypoxia-resistant cultivar, Lübachun 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). O(-*)(2) and H(2)O(2) 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 (Fig.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.
以耐低氧品种绿霸春4号和低氧敏感品种中农8号黄瓜幼苗为试材，采用根系供液的方式，研究了外源24-表油菜素内酯（EBR）对低氧胁迫下黄瓜幼苗根系脂质过氧化、主要抗氧化酶和无氧呼吸酶活性及其时间进程的影响。低氧胁迫显著抑制根系生长，外源EBR处理可缓解这种抑制作用（图1、2）。低氧胁迫下，根系中O(-*)(2)和H(2)O(2)水平及脂质过氧化显著增加，外源EBR处理可抑制这种增加（图3）。EBR处理提高了低氧胁迫下的超氧化物歧化酶（SOD）和过氧化物酶（POD）活性（图4）。低氧增强了乳酸脱氢酶（LDH）、乙醇脱氢酶（ADH）和丙酮酸脱羧酶（PDC）的活性，而EBR处理显著提高了ADH活性，但降低了LDH活性（图5）。低氧胁迫处理与“低氧+EBR”处理之间的过氧化氢酶（CAT）和PDC活性无显著差异（图4、5）。从本研究结果可以得出结论，EBR处理可显著减轻低氧胁迫对幼苗根系的氧化损伤，并增强乙醇发酵。
