玉米发芽过程中Cd和硫醇化合物相互作用的研究

The Interaction Between Cd and Thiol Compounds During the Maize Seed Germination

随着现代工业的发展,重金属镉(Cd)对农作物的污染情况日趋严重,作为广泛传播的污染物,Cd易于通过土壤被农作物吸收。为了研究玉米对毒性金属积累、暴露响应和耐受机制,以探讨玉米发芽过程中Cd与硫醇化合物相互作用机理为目的,利用毛细管电泳等分析技术,研究了Cd对玉米发芽势、发芽率的影响,培养液中Cd2+对玉米种子中Cd含量的影响,Cd-硫醇化合物吸收光谱和玉米种子中硫醇化合物含量水平。结果表明,发芽率和发芽势呈无规律性变化;当玉米经过含Cd2+培养液浸泡时,存在着Cd2+在二者间的相互迁移作用,且迁移作用呈线性关系(5 d除外);当Cd与硫醇化合物共存时,Cd-硫醇化合物吸收光谱暗示形成金属硫蛋白;硫醇化合物含量随Cd的存在呈现先增加后减少的变化规律,Cd2+浓度为50μmol.L-1时含量达最大值,更高浓度时,其含量降至低于空白对照样品值。研究结果表明,不同种类的硫醇化合物含量可间接指示金属Cd对植物种子发芽毒害影响程度。

The heavy metal Cd is present in varying amounts in agricultural crops.It is a widely spread pollutant.With the development of industry,it can reach high levels in agricultural soils and easily be assimilated by plants.During the bio-process of maize germination,capillary electrophoresis and other modern analytical techniques were used to explore the interaction mechanism between Cd and thiol compounds.Cd impacted maize germination viability,germination rate,culture medium Cd2＋ impacted the Cd content of maize seeds,the Cd-thiol compounds absorption spectra and thiol compounds content in maize seed were investigated.The results of our experiments suggested that the germination rate and germination viability changed irregularly with the increase of Cd2＋ concentration and cultivating days.The intermigration of Cd2＋ occurred when the maize immersed the culture medium containing Cd2＋,and the migration had a linear relationship（except for 5 days）with the increase of Cd2＋.Under the co-existence of Cd and thiol compounds,the Cd-thiol compounds absorption spectra implied the formation of Metallothionein.The content of thiol compounds increased and then decreased with Cd existence.The content reached maximum value as Cd2＋ concentration was 50 μmol·L-1.When Cd2＋ concentration was higher,the content decreased significantly below the level of the untreated control sample.The compounds were the indicators of the effect of Cd on the formation of potential heavy metal responsing on plant seed germinating.