不同Cd积累基因型烟草中Cd的亚细胞分布及化学形态

Subcellular Distribution and Chemical Forms of Cd in Two Tobacco Genotypes with Different Cd Accumulating Pattern

采用苗期水培试验,以Cd积累模式不同的两个烟草基因型普通烟草品种K326(根系和叶片积累)和黄花烟草品种N.rustica(根系积累)为试材,比较了不同Cd浓度下(1μmol/L和50μmol/L)两个基因型烟草根系和叶片中Cd的亚细胞分布和化学赋存形态。结果表明:①Cd浓度1μmol/L时,K326表现为根系和叶片积累,N.rustica以根系积累为主;高Cd浓度下两者均显示根系积累特性。②Cd浓度1μmol/L时,K326和N.rustica中Cd主要结合于可溶组分中,且两个基因型烟草中Cd在可溶组分中的积累比例高低与相应部位Cd积累总量大小相一致。表明Cd在可溶组分中截留比例可能是造成普通烟草和黄花烟草Cd积累特征不同的影响因素之一。③两个基因型烟草根系中Cd以乙醇提取态为主,叶片中Cd主要以氯化钠结合态和去离子水结合态存在。提高Cd处理浓度,Cd存在由活性强的化学形态向活性弱的形态转化的趋势。但在两基因型烟草中Cd的化学形态没有明显的的种间差异,表明两基因型烟草对Cd积累的差异与其化学赋存形态关系不大。

An experiment on hydroponic seedlings was carried out to study the subcellular distribution and chemical forms of Cd in the root system and leaves of two tobacco genotypes（K326 and N.Rustica） with different Cd accumulation pattern at different Cd treatment level（1 and 50 μmol/L）.The results showed that： 1） At low level,Cd accumulated in root system and leaves of K326,while accumulated mainly in root system of N.rustica.At high level,Cd mainly accumulated in root system of both varieties.2） At low level,Cd mainly bound to the soluble fraction in both varieties,which accounted for about 70% of the total Cd content.The Cd retention by cell wall increased significantly in K326 at high Cd level.3） The binding proportion of Cd in soluble fraction always identical with the Cd content in respective parts,which indicated that the difference of binding ability in soluble fraction might be one of the major factors affecting Cd accumulation in the two genotypes.4） Ethanol-extractable Cd in root systems of K326 and N.rustica accounted for 72.15% and 71.36% of the total Cd,respectively,it was the main chemical form of Cd in root system.In leaves,Cd mainly existed in the forms of binding to NaCl and deionized water.No significant difference was observed between the chemical forms of Cd in the two genotypes,which indicated that Cd accumulation in tobacco was not relevant to its chemical form.