2种蓖麻对镉的吸收及解毒机制研究

Mechnisms of cadmium absorption and detoxicity of two castors

蓖麻对镉(Cd)有明显的富集能力,并对镉污染的土壤有一定的修复效果,探究蓖麻体内镉的解毒机制非常重要。选择镉高富集的蓖麻品种淄博8号(ZB-8)和镉低富集蓖麻品种航蓖8号(HB-8)进行比较性研究。结果发现,从耐性指数看,ZB-8比HB-8具有较高的耐性。对蓖麻叶片中亚细胞组分进行分析,发现ZB-8的叶片中镉主要结合在金属富集颗粒及热稳定蛋白,其叶片中生物解毒组分的含量显著高于HB-8(P<0.01)。同时对ZB-8和HB-8叶片、木质部和韧皮部液中谷胱甘肽(GSH)和植物络合素(PCs)含量进行分析,发现HB-8韧皮部GSH含量显著高于ZB-8,且HB-8木质部液及韧皮部液中PCs含量均显著高于ZB-8(P<0.01)。木质部和韧皮部液中高浓度的PCs与镉结合,可能降低了镉在HB-8中的迁移能力,从而导致镉在HB-8叶片中富集量较ZB-8低。同时ZB-8叶片中较高浓度PCs降低了镉在其体内的毒性。

To investigate the mechanisms of cadmium absorption and detoxicity of castor（Ricinus communisL.）, two castor cultivars（ZB-8 and HB-8） were used for hydroponic experiments. The results indicated that both cultivars had a high tolerance to Cd. The investigation of subcellular Cd partitioning showed that Cd was mainly accumulated in the heat stable protein and cellular debris fractions in the leaf of ZB-8, and the biologically detoxified fraction（BDM） of ZB-8 was significantly higher than that in HB-8（P〈0.01）. The contents of GSH and PCs in the xylem, phloem and leaf of the two cultivars were also determined. The results showed that GSH content in the phloem of HB-8 was significantly higher than that in ZB-8, and the PCs contents in the xylem and phloem of HB-8 were both significantly higher than those in ZB-8（P〈0.01）. The higher tolerance of ZB-8 compared with HB-8 could be attributed to the higher PCs levels in the leaf. The higher contents of PCs and GSH in the xylem and phloem of HB-8 decreased Cd transport ability from the root to the shoot.