Department of Biochemistry, Kansas State University, Manhattan, KS 66506, USA.
J Environ Qual. 2011 May-Jun;40(3):719-30. doi: 10.2134/jeq2010.0143.
Infrared microspectroscopy (IMS) is emerging as an important analytical tool for the structural analysis of biological tissue. This report describes the use of IMS coupled to a synchrotron source combined with principal components analysis (PCA) to monitor the fate and effect of dinitrotoluenes in the roots of maize and sunflower plants. Infrared imaging revealed that maize roots metabolized 2,4-dinitrotoluene (DNT) and 2,6-DNT. The DNTs and their derivative aromatic amines were predominantly associated with epidermis and xylem. Both isomers of DNT altered the structure and production of pectin and pectic polysaccharides in maize and sunflower plant roots. Infrared peaks diagnostic for aromatic amines were seen at the 5 mg L concentrations for both DNTs in maize and sunflower treated tissue. However, only infrared peaks for nitro groups, not aromatic amines, were present in the maize treated at 10 mg L For sunflower, the 10 mg L level was toxic and also produced very dark root systems making spectra difficult to obtain. Maize and sunflower seem unable to metabolize effectively at concentrations higher than about 5 mg L DNT in hydroponic solution. Based on the results of this study, IMS combined with PCA can be an effective means of determining the fate and metabolism of organic contaminants in plant tissue when isotopically labeled compounds are not available.
红外显微光谱学（IMS）正成为生物组织结构分析的重要分析工具。本报告描述了将 IMS 与同步辐射源耦合并结合主成分分析（PCA）用于监测二硝基甲苯在玉米和向日葵植物根部的命运和影响。红外成像显示，玉米根代谢 2,4-二硝基甲苯（DNT）和 2,6-DNT。DNTs 及其衍生的芳香胺主要与表皮和木质部有关。两种 DNT 异构体都改变了玉米和向日葵植物根中原果胶和果胶多糖的结构和产量。在玉米和向日葵处理组织中，DNTs 的浓度为 5 mg/L 时就可以看到诊断性的芳香胺红外峰。然而，只有在浓度为 10 mg/L 的玉米处理组织中存在用于检测硝基基团的红外峰，而不是芳香胺。对于向日葵，10 mg/L 的浓度是有毒的，并且还会产生非常暗的根系，使得光谱难以获得。玉米和向日葵似乎无法在水培溶液中有效代谢浓度高于约 5 mg/L 的 DNT。基于这项研究的结果，当无法获得同位素标记化合物时，IMS 结合 PCA 可以成为确定植物组织中有机污染物命运和代谢的有效手段。
