侧柏和国槐叶片中铅的化学形态与分布研究

为了解铅在植物体内的迁移转化规律,采用盆栽试验,结合细胞组分分离和化学形态提取技术,研究了不同外源铅浓度处理下（CK0mg.kg-1,A300mg.kg-1,B500mg.kg-1,C1000mg.kg-1,D2000mg.kg-1）侧柏和国槐不同器官的铅含量及其在两种植物叶片细胞中的分布和化学结合形态。结果表明：在铅胁迫下,侧柏和国槐的生物量均发生显著变化;两种植物体内的铅随着外源铅浓度的增加而显著增加,且主要分布在根部。侧柏和国槐叶片亚细胞中铅的含量分布及结合形态存在差异。细胞壁是铅在侧柏和国槐叶片细胞内的主要分布位点,其次是细胞核部分和叶绿体线粒体部分,可溶性部分最少,随着外源铅浓度的增加,细胞核部分的分配增加,可溶性部分减少,但侧柏叶片中细胞壁部分所占比例大于国槐叶片中细胞壁部分的百分率。两种植物叶片内均以NaCl提取态、HAc提取态和HCl提取态铅为主导形态,水和乙醇两种提取态铅的分配很少;随着外源铅浓度的增加,侧柏叶片中NaCl提取态铅先增加后减少,国槐叶片中NaCl提取态铅所占百分率不断增加。侧柏对铅的耐受能力强于国槐。

Chemical Forms and Distribution of Pb in the Leaves of Platycladus orientalis and Sophora japonica

A pot experiment combined with subcellular fractionation and chemical speciation sequential extraction techniques was carried out to study the lead（Pb）distribution and chemical forms in leaves of Platycladus orientalis and Sophora japonica under different Pb concentration（CK 0 mg.kg-1,A 300 mg.kg-1,B 500 mg.kg-1,C 1000 mg.kg-1,D 2000 mg.kg-1）.The result showed that the biomass of Platycladus orientalis and Sophora japonica changed significantly under Pb stress.Most of Pb was distributed in the roots of two plants,and which increased with the Pb concentration in soil.A difference was observed in subcellular distribution of Pb and its chemical forms between the two plants leaves under Pb stress.Most of Pb was found to be bound to cell wall in the leaves of Platycladus orientalis and Sophora japonica for all Pb treatments,and the proportion of Pb bound to cell wall was higher in Platycladus orientalis than Sophora japonica.Less Pb was distributed in soluble fractions for both plants.The proportion of cell nucleus raised with Pb concentration increased,whereas the proportion of soluble fractions decreased.For the chemical forms,NaCl,acetic acid and HCl-extractable Pb were predominated in the leaves of the two plants,while the proportion of water and ethanol-extractable Pb were little.Pb supply increased the proportion of NaCl-extractable Pb firstly,and which reduced in leaves of Platycladus orientalis thereafter.On the contrast,the proportion of NaCl-extractable Pb in leaves of Sophora japonica increased gradually with Pb supply increased.Based on these fingings,Platycladus orientalis was likely to possess a higher tolerance to Pb than Sophora japonica did.