Ferrous ions (Fe²⁺) in the rhizosphere play an indispensable role in the interaction between plants and nanoparticles (NPs). Here, we investigated the effect of Fe²⁺ (3 mM) on the dynamic adsorption, uptake and accumulation of CuO NPs (100 mg L⁻¹) by rice plants using μ-XRF combined with metabolomics. The results show that the Cu content adsorbed by roots at 72 h was reduced by 71% compared to that at 6 h with the formation of sufficient amorphous iron plaque induced by Fe²⁺, which was consistent with the inverse changes of Fe and Cu intensities in μ-XRF mappings. Furthermore, the absorbed Cu contents in the roots and shoots were dramatically reduced by 90.3% and 47.2% compared to those exposed to only NPs at 72 h, respectively, due to the presence of Fe²⁺. The supply of Fe²⁺ triggered the decline in Cu contents of the roots and shoots from 6 h to 72 h by up to 81.5% and 41.3%. Metabolomics analysis indicates that Fe²⁺ markedly downregulated abundant organic acids and amino acids with respect to the control and NP treatment, but significantly upregulated fatty acids compared to the NP treatment, thus lessening the Cu accumulation in rice. This study provides new ideas for alleviating the stress caused by NPs in plants.

中文翻译：

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亚铁离子通过诱导铁斑块和调节暴露于CuO纳米颗粒的水稻植物的代谢来抑制Cu的吸收和积累

根际中的亚铁离子（Fe ²⁺）在植物与纳米颗粒（NP）之间的相互作用中起着不可或缺的作用。在这里，我们使用μ-XRF和代谢组学研究了Fe ²⁺（3 mM）对水稻植株对CuO NPs（100 mg L ^-1）的动态吸附，吸收和积累的影响。结果表明，通过在72小时根吸附在Cu含量降低了71％相比，在6小时与由铁引起的足够的无定形铁斑的形成²⁺，这与μ-XRF映射中Fe和Cu强度的逆变化一致。此外，与在72 h只暴露于NPs的根相比，由于存在Fe ²⁺，根和茎中吸收的Cu含量分别显着降低了90.3％和47.2％。Fe ²⁺的供应导致根和芽的Cu含量从6 h下降到72 h，分别降低了81.5％和41.3％。代谢组学分析表明，相对于对照和NP处理，Fe ²⁺显着下调了丰富的有机酸和氨基酸，但是与NP处理相比，Fe ²⁺显着上调了脂肪酸，从而减少了水稻中的Cu积累。这项研究为减轻植物中NPs引起的胁迫提供了新思路。