不同镉耐性水稻非蛋白巯基及镉的亚细胞和分子分布

采用镉(Cd)耐性不同的水稻品种N07-6和N07-63,通过室内水培试验,比较了50μmol·L-1Cd胁迫下水稻的非蛋白巯基(NPT)、Cd的亚细胞和分子分布的差异。结果表明,Cd处理后,两品种水稻植株Cd含量存在明显差异,N07-63根部向地上部转移的Cd显著少于N07-6。Cd胁迫诱导了两个品种NPT含量的增加,N07-63的增幅显著高于N07-6。Cd绝大部分分布在水稻的细胞壁和细胞可溶部分。N07-63茎叶和根部细胞壁结合的Cd占总Cd的比例高于N07-6,而细胞可溶部分Cd的比例低于N07-6。从Cd的分子分布来看,水稻茎叶细胞可溶部分的Cd一部分与大分子量蛋白质结合,其余大部分与植物螯合肽(PCs)结合,而根细胞可溶部分的Cd绝大部分与PCs络合,N07-63的Cd-PCs结合程度高于N07-6。由此说明,与N07-6相比,N07-63细胞壁对Cd的束缚和细胞可溶部分Cd-PCs的络合程度更高,Cd的毒害效应更小,向地上部转运的Cd更少。

Non-protein Thiols,Subcellular and Molecular Distribution of Cadmium in Two Rice Cultivars with Difference Tolerance

A hydroponic experiment was conducted to study the content of non-protein thiols(NPT),subcellular and molecular distributions of Cd in the two rice cultivars(N07-6 and N07-63)with different tolerance treated with 50 μmol·L-1 Cd.The results showed that Cd contents differed clearly in two rice eultivars after Cd treatment.The amount of Cd translocated from root to shoot in N07-63 was significantly lower than that in N07-6.Cadmium induced increases of NPT contents for the two eultivars,and the increment of N07-63 was significantly higher than N07-6.Most Cd was distributed in the cell wall and cellular soluble fractions.Compared with N07-6,N07-63 had higher proportions of total Cd in the cell wall of shoot and root,but lower in the cellular soluble fractions.From the molecular distribution of Cd in rice,we observed that Cd was associated partly with proteins with large molecular weight in shoot cellular soluble fraction.The rest was mainly bound to phytocbelatins(PCs).However,most Cd was complexed with PCs in the soluble fraction of rice root cells,and the association between Cd and PCs was stronger in N07-63 than that in N07-6.Therefore,Cd toxicity and translocation were lower in N07-63 due to the more Cd binding in the cell wall and more chelation between Cd and PCs in the cellular soluble fraction.