低氧胁迫下苹果砧木根系的膜脂过氧化作用及其抗氧化机理

Membrane-lipid Peroxidation and Anti-oxidative Mechanism in Roots of Apple Stocks under Hypoxia Stress

采用营养液水培的方法,以苹果砧木平邑甜茶(Malus hupenensis Rehd.)和变叶海棠(Malus toringoides Rehd.)为试材,研究了低氧胁迫下两种苹果砧木根系的膜脂过氧化作用及其抗氧化系统的响应.结果表明,低氧胁迫下苹果砧木根系超氧阴离子(O2-˙)产生速率和过氧化氢(H2O2)含量增加,丙二醛(MDA)含量上升,且随时间延长呈快―慢―快的变化趋势.同时根系中超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)的活性增加,抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)的活性前期有所提高而后期降低并低于对照,抗坏血酸(AsA)和还原型谷胱甘肽(GSH)含量以及抗坏血酸/脱氢抗坏血酸(AsA/DHA)和还原性谷胱甘肽/氧化性谷胱甘肽(GSH/GSSG)比值在胁迫早期增加而后逐渐减少,中期和后期低于同期对照.变叶海棠根系细胞膜受到的氧化伤害大于平邑甜茶,其抗氧化系统的防御能力也弱于后者.说明低氧胁迫下苹果砧木根系活性氧(ROS)积累,细胞膜脂质过氧化加重,植株根系的抗氧化防御系统能在一定程度上减轻低氧胁迫所造成的膜伤害,但当胁迫持续加重时,植株将受到更大的氧化伤害.

By means of nutrient solution culture, Malus hupenensis Rehd and M. toringoides Rehd., which was high hypoxia-tolerant and hypoxia-sensitive respectively under hypoxia stress, were used to study the membrane-lipid peroxidation and anti-oxidative mechanism in their roots. The results showed that the generation rate of superoxide radical （O2^-） and content of hydrogen peroxide （H2O2） increased in the roots of apple stocks under hypoxia stress, and the content of malonaldehyde （MDA） increased as well. The changing trend was found as slow-fast-slow during the stress. At the same time, the activities ofperoxidse （POD）, superoxide dismutase （SOD） and catalase （CAT） increased during the stress, the activities of ascorbate peroxidase （APX） and glutathione reductase（GR） increased in early period of the stress, and then decreased in later period at a rate less than the control. The contents of antioxidants such as ascorbic acid （AsA） and glutathione （GSH）, the ratio of AsA and oxidative ascorbic acid （AsA/DHA）, the ratio of GSH and oxidative glutathione （GSH/GSSG） also increased in the early period, and then gradually decreased later, and were less than those of control in media and later period of stress. The oxidative damages to membrane in roots of M. toringoides were more serious than those of M. hupenensis, and the defense capability of anti-oxidative system of the former was less than that of the latter. The data indicated that the hypoxia stress led to the accumulation of reactive oxygen species （ROS） in the roots of apple stocks, so the membrane lipid peroxidation was more serious. The anti-oxidative system could reduce these damages to some extent, but when the stress continued over the limit, the plants would have greater oxidative damage. Fig 5, Ref 21