类芦根细胞壁对铅的吸附固定机制

为探究类芦对Pb的耐性机制,采用对根细胞壁化学改性处理,测定Pb吸附动力学。结果表明,通过酯化改性去除部分羟基官能团后的根细胞壁对Pb~(2+)的吸附量相对降低了68.1%,其次为通过果胶酶改性去除部分果胶和通过甲基化改性去除部分氨基后的细胞壁,对Pb2+的吸附量相对降低48.9%与41.1%。利用傅里叶红外光谱分析,再结合FTIR图可得出,果胶提供的羟基基团、纤维素和半纤维素提供的羧基基团以及细胞壁蛋白提供的氨基官能团都是类芦固定Pb~(2+)的重要位点。研究表明,细胞壁组分中的羟基、羧基和氨基可以提供Pb结合位点,特别是羟基官能团可以使细胞壁对Pb具有较高的吸附固定能力,这也是类芦能够抵御Pb胁迫的一种重要机制。

Lead adsorption and fixation mechanisms in root cell walls of Neyraudia reynaudiana

Neyraudia reynaudiana is a plant with a large biomass, low soil nutrient tolerance, and high enrichment ability for the heavy metal Pb. In order to study the Pb tolerance mechanisms of Neyraudia reynaudiana, the root cell wall was studied by chemical modification, and the Pb adsorption kinetics were determined. The results show that, first, the amount of Pb²⁺ adsorbed by the root cell wall was reduced by 68.1% after partial hydroxyl functional group removal by esterification. Second, pectinase removed some of the pectin from the cell wall, after partial amino group removal by methylation. These two processes decreased the amount of Pb adsorbed by 48.9% and 41.1%, respectively. Fourier infrared spectroscopy was used to study the Pb²⁺ adsorption capacity of different components of the Neyraudia reynaudiana cell wall. The hydroxyl group provided by pectin, the carboxyl group provided by cellulose and hemicellulose, and the amino functional group provided by cell wall proteins, are all important sites for Neyraudia reynaudiana to immobilize Pb²⁺. This shows that the hydroxyl group, carboxyl group and amino group can all provide Pb binding sites in the cell wall; in particular, the hydroxyl functional group enables the cell wall to have a high Pb adsorption and immobilization ability, and constitutes an important mechanism for Neyraudia reynaudiana to resist Pb stress.