硒对水稻镉毒性的影响及其机制的研究

Alleviation by Selenium of Cadmium Toxicity to Rice and Its Mechanisms

为探究外源四价硒[Se(Ⅳ)]对水稻镉(Cd)吸收和分布的影响,采用水培试验方法,参考稻田土壤淹水后硒的主要存在形态,研究外源Se(Ⅳ)对不同浓度Cd处理下水稻Cd吸收、转运的影响及其解毒机制。结果表明,在低浓度Cd处理(0.5μmol·L-1)下,外源Se(Ⅳ)对水稻Cd的积累和分布影响不显著,但在高浓度Cd处理(5.0μmol·L-1)下,外源Se(Ⅳ)会显著降低水稻对Cd的吸收和转运。不同浓度Cd处理均会增加水稻对Se的吸收,影响Se在水稻体内的分布,并且显著减少Se向地上部的转运。Cd、Se复合处理会导致水稻地下部非蛋白巯基(NPT)含量增加,同时改变Cd在地下部的亚细胞分布,使细胞壁组分的Cd含量上升,细胞可溶物质组分和细胞器组分的Cd含量下降,从而减少Cd向茎叶的转运,降低地上部的膜脂过氧化程度。由于试验所选用的水稻品种对Cd、Se抗性较强,不同处理下水稻地上部抗氧化酶活性与总抗氧化容量差异均不显著,且水稻生物量及表型特征也无显著差异。

Minimizing cadmium（Cd）accumulation in rice grain is crucial to food safety. In this study, a hydroponic experiment was performed to investigate the effects of exogenous selenite[Se（Ⅳ）], a dominant Se species in rice paddy soils after flooding, on Cd absorption,translocation and detoxification in rice under different Cd concentrations. Selenite markedly reduced Cd accumulation and translocation in rice in high Cd（5.0 μmol·L^-1）treatment but had no significant influence in low Cd（0.5 μmol·L^-1）treatment. However, Cd at both low and high concentrations increased Se absorption but reduced Se transport to the aboveground part of rice. Combined Cd-Se treatment enhanced root non-protein thiol（NPT） concentrations, changed Cd subcellular distributions in rice root, with increased Cd in cell walls and de-creased Cd in cellular organelles and soluble fractions, thus reducing Cd translocation to the aboveground and lipid peroxidation in the cell membrane of rice shoot. Due to the strong tolerance of the rice cultivar to Se and Cd, the activities of antioxidant enzymes and total anti-oxidation capacity in rice shoot did not differ significantly among various treatments, and rice biomass and phenotypic characteristics were unaffected either.