Ca^(2+)对过量Fe^(2+)胁迫下水稻保护酶活性及膜脂过氧化的影响

Effect of Ca^(2+) on Antioxidant Enzymes and Lipid Peroxidation in Rice under Excessive Fe ^(2+) Stress

采用水培法研究了不同浓度 Ca2 +在过量 Fe2 +胁迫下对水稻生长、保护酶 (SOD、POD、CAT)活性及脂质过氧化的影响。结果表明 ,Fe2 +供应正常时 ,10 0～ 30 0 m g kg- 1 Ca2 +的水培液能不同程度地促进水稻生长 ,提高 SOD、POD活性 ,而对 CAT的影响不大 ,高钙 (4 0 0 mg kg- 1 )供应则会加剧脂质过氧化。在过量 Fe2 +胁迫下 ,10 0～ 30 0 m g kg- 1 Ca2 +能较好地促进 Azucena的地上部及根系的干物质积累量 ,对 IR6 4的干物质积累量则以 30 0 mg kg- 1 Ca2 + 供应为最佳。适量的 Ca2 + 供应能提高植物体内 SOD、POD和 CAT的活性或使之保持在较高水平上 ,并使 MDA含量维持在较低水平。Ca2 +能较好地提高粳稻 Azucena对过量 Fe2 +胁迫的耐性。表明适合浓度 Ca2 +供应提高水稻耐铁毒能力的原因之一 ,在于增强了植株活性氧清除能力和对生物膜结构的稳定作用。

A solution culture was conducted to study the ameliorating effect of Ca 2+ on excessive Fe 2+ stress on a tolerant genotype (Azucena) and a sensitive genotype (IR64) of rice and their associated physiological variations such as the activities of several protective enzymes, lipid peroxidation and biomass accumulation of rice cultivars were also investigated. The results showed that under normal Fe 2+ level, Ca 2+ concentration at 100—300 mg kg -1 could increase plant growth and SOD and POD activity, with little effect on CAT activity. Ca 2+ concentration at 400 mg kg -1 obviously enhanced lipid peroxidation. Under excessive Fe 2+ stress, ameliorating effect of Ca 2+ at 100 mg kg -1 level was observed, which was indicated by the increase of shoot and root biomass. Moreover normal levels of SOD, POD and CAT activities were maintained or/and enhanced, with a reduction of lipid peroxidation. The mitigative effect of Ca 2+ on excessive Fe 2+ stress was more pronounced in Azucena than in IR64. The above results strongly suggested that the elimination of active oxygen and maintenance of membrane stability accounted to some extent for the mechanism of ameliorating effect of Ca 2+ on excessive Fe 2+ stress.