有机质在土壤和水环境中广泛存在，对污染物的环境行为及生态毒性影响较大。目前，人们对有机质影响重金属的植物毒性及相关机制缺乏了解。日前，中国林业科学研究院亚林所陈光才副研究员研究了可溶性有机质对金属氧化物Nd2O3（三氧化二钕，纳米颗粒、微米颗粒和离子）的植物毒性影响机制并取得进展。相关成果发布于《纳米毒理学》。

科研人员发现，Nd2O3显著降低水培体系中植物的生长及对硫、钙、钾和镁等矿质元素的吸收，营养液中添加小分子量有机质单宁酸能显著减轻Nd2O3颗粒的植物毒性。他们从金属氧化物颗粒的环境行为、植物生理生化响应、植物基因表达水平等层次揭示了可溶性有机质缓解Nd2O3纳米/微米颗粒植物毒性的机制：单宁酸把Nd2O3纳米/微米颗粒的表面电荷从正变副，减少了其在根系表面的吸附、根系吸收和积累，单宁酸恢复了植物受Nd2O3抑制的硫、钙、钾和镁的吸收、转运；单宁酸调高了一些抗氧化酶基因的表达水平、提高了抗氧化酶的活性来清除超氧自由基，从而减轻了Nd2O3的植物毒性。

该结果对于深入了解不同形态重金属的植物毒性、有机质缓解重金属植物毒性机制方面具有重要意义。（来源：科学网 彭科峰）

Tannic acid alleviates bulk and nanoparticle Nd₂O₃ toxicity in pumpkin: a physiological and molecular response

Abstract  The effect of dissolved organic matter (DOM) on nanoparticle toxicity to plants is poorly understood. In this study, tannic acid (TA) was selected as a DOM surrogate to explore the mechanisms of neodymium oxide NPs (Nd₂O₃ NPs) phytotoxicity to pumpkin (Cucurbita maxima). The results from the tested concentrations showed that 100 mg L⁻¹ Nd₂O₃ NPs were significantly toxic to pumpkin in term of fresh biomass, and the similar results from the bulk particles and the ionic treatments were also evident. Exposure to 100 mg L⁻¹ of Nd₂O₃ NPs and BPs in 1/5 strength Hoagland’s solution not only significantly inhibited pumpkin growth, but also decreased the S, Ca, K and Mg levels in plant tissues. However, 60 mg L⁻¹ TA significantly moderated the observed phytotoxicity, decreased Nd accumulation in the roots, and notably restored S, Ca, K and Mg levels in NPs and BPs treated pumpkin. TA at 60 mg L⁻¹ increased superoxide dismutase (SOD) activity in both roots (17.5%) and leaves (42.9%), and catalase (CAT) activity (243.1%) in the roots exposed to Nd₂O₃ NPs. This finding was confirmed by the observed up-regulation of transcript levels of SOD and CAT in Nd₂O₃ NPs treated pumpkin analyzed by quantitative reverse transcription polymerase chain reaction. These results suggest that TA alleviates Nd₂O₃ BPs/NPs toxicity through alteration of the particle surface charge, thus reducing the contact and uptake of NPs by pumpkin. In addition, TA promotes antioxidant enzymatic activity by elevating the transcript levels of genes involved in ROS scavenging. Our results shed light on the mechanisms underlying the influence of DOM on the bioavailability and toxicity of NPs to terrestrial plants.

原文链接：http://www.tandfonline.com/doi/full/10.1080/17435390.2016.1202349