Ascolani Yael J, Fuhr J D, Bocan G A, Daza Millone A, Tognalli N, Dos Santos Afonso M, Martiarena M L
Instituto Balseiro, Centro Atómico Bariloche (CNEA), Universidad Nacional de Cuyo , Avenida Exequiel Bustillo 9500, 8400 San Carlos de Bariloche, Argentina.
J Agric Food Chem. 2014 Oct 8;62(40):9651-6. doi: 10.1021/jf502979d. Epub 2014 Sep 29.
Glyphosate [N-phosphono-methylglycine (PMG)] is the most used herbicide worldwide, particularly since the development of transgenic glyphosate-resistant (GR) crops. Aminomethylphosphonic acid (AMPA) is the main glyphosate metabolite, and it may be responsible for GR crop damage upon PMG application. PMG degradation into AMPA has hitherto been reckoned mainly as a biological process, produced by soil microorganisms (bacteria and fungi) and plants. In this work, we use density functional calculations to identify the vibrational bands of PMG and AMPA in surface-enhanced Raman spectroscopy (SERS) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra experiments. SERS shows the presence of AMPA after glyphosate is deposited from aqueous solution on different metallic surfaces. AMPA is also detected in ATR-FTIR experiments when PMG interacts with metallic ions in aqueous solution. These results reveal an abiotic degradation process of glyphosate into AMPA, where metals play a crucial role.
草甘膦[N-膦酰基甲基甘氨酸（PMG）]是全球使用最广泛的除草剂，尤其是自转基因抗草甘膦（GR）作物问世以来。氨甲基膦酸（AMPA）是草甘膦的主要代谢产物，在施用PMG时，它可能是造成GR作物受损的原因。迄今为止，PMG降解为AMPA主要被认为是一个由土壤微生物（细菌和真菌）及植物产生的生物过程。在这项工作中，我们利用密度泛函计算来识别表面增强拉曼光谱（SERS）和衰减全反射傅里叶变换红外光谱（ATR-FTIR）实验中PMG和AMPA的振动谱带。SERS显示，草甘膦从水溶液沉积到不同金属表面后会出现AMPA。当PMG在水溶液中与金属离子相互作用时，在ATR-FTIR实验中也能检测到AMPA。这些结果揭示了草甘膦向AMPA的非生物降解过程，其中金属起着关键作用。
