镉胁迫对镉敏感水稻突变体活性氧代谢及抗氧化酶活性的影响

Effects of cadmium stress on reactive oxygen species metabolism and antioxidant enzyme activities in Cd-sensitive mutant rice seedlings

镉是一种常见的环境有毒重金属元素,不仅影响植物的生长和发育,而且还通过食物链危害人类健康。因此研究镉对植物的影响、分析植物逆境生理过程,对损伤和抗逆机理研究具有重要意义。以镉敏感水稻突变体和野生型(OryzasativaL.)为材料,采用营养液培养实验,研究了不同浓度镉对水稻叶片活性氧代谢及抗氧化酶化系统的影响。结果表明:镉胁迫使水稻叶片超氧阴离子(O2??)、过氧化氢(H2O2)、丙二醛(MDA)含量增加,且突变体的增加幅度明显大于野生型。随着镉浓度的提高,超氧化物歧化酶(SOD)和过氧化物酶(G-POD)活性均表现为先上升后下降,但SOD活性的变化更明显;过氧化氢酶(CAT)活性则呈一直下降的趋势。在较高镉浓度胁迫下(>5μmolL-1),突变体叶片的SOD、CAT活性均明显低于野生型。研究结果表明,随着镉胁迫浓度的增加,突变体叶片积累更多的活性氧,产生严重的氧化胁迫,引起了更高程度的膜脂过氧化,这可能是突变体对镉胁迫更敏感的生理原因之一。

Cadmium （Cd） is one of the most common environmental poisonous heavy metal elements, which not only affects adversely the plant growth and development, but also causes harmful effects on human health by food chains at high concentration. It is important to study the mechanism for resistance to Cd damage in plant. The reactive oxygen species metabolism and antioxidant enzyme system in the leaves of Cd-sensitive mutant and wild type rice （Oryza sativa L. subsp. Japonica, cv. Zhonghua 11） were studied with a hydroponic experiment under different Cd concentrations. The results showed that the addition of Cd in the nutrient solution increased the contents of superoxide dismutase （O2-·）, H2O2 and malondialdehyde （MDA）, which would be more pronounced in the mutant than those of wild type. The activities of SOD were firstly increased, then decreased with the increased concentration of Cd, while the activities of catalase （CAT） were decreased. The activities of SOD and CAT in the mutant were significantly lower than those in the wild type under relative higher Cd treatment （〉5 μmol·L^-1）. Our results indicated that Cd caused more accumulation of reactive oxygen species and oxidative stress and more level of lipid peroxidation in the mutant at higher Cd concentrations, which might be a physiological explanation for sensitiveity to Cd.