Nanotechnology has a wide range of applications, and the pollution and toxicity of their overuse must also be taken seriously. The dual effects of cerium oxide nanoparticles (CeO₂ NPs) on alfalfa (Medicago sativa L.) through regulating programmed cell death (PCD) were investigated. Herein, foliar spray of CeO₂ NPs on alfalfa revealed a dose-dependent effect of CeO₂ NPs. CeO₂ NPs at low concentrations had a positive effect but those at high concentrations had phytotoxicity. Specifically, 100 mg L⁻¹ CeO₂ NPs improved the morphology, biomass, pigments, photosynthesis, stomatal opening, ultrastructure, osmotic and redox homeostasis, the antioxidant enzyme and the anti-PCD genes, and several hormones, accompanied by lower PCD-promoting gene expression and cellular features. Conversely, 1000 mg L⁻¹ CeO₂ NPs induced PCD by causing oxidative damage, along with negative morphology, reduced quality, high Ce accumulation, weak photosynthesis, stomatal closure, lipid peroxidation, apoptosis, impaired cellular ultrastructure, DNA fragmentation, osmotic and redox instability, gene alterations, and hormonal fluctuations. Overall, alfalfa responds to the duality of CeO₂ NPs by controlling PCD, which is regulated by a complex network. This study proposes a fresh outlook on the rational utilization of CeO₂ NPs, the promotion of sustainable agriculture, and the prevention of environmental pollution caused by nanomaterials.

中文翻译：

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关于叶面施用氧化铈纳米粒子对苜蓿（Medicago sativa L.）生长的双向影响的多重见解


纳米技术有着广泛的应用领域，但过度使用其带来的污染和毒性也必须引起重视。研究了氧化铈纳米粒子（CeO ₂ NPs）通过调节程序性细胞死亡（PCD）对苜蓿（Medicago sativa L.）的双重作用。在此，在苜蓿上叶面喷施 CeO ₂ NPs 揭示了 CeO ₂ NPs 的剂量依赖性效应。 CeO ₂ NPs在低浓度时具有积极作用，但在高浓度时具有植物毒性。具体而言，100 mg·L ⁻¹ CeO ₂ NPs 改善了形态、生物量、色素、光合作用、气孔开放、超微结构、渗透和氧化还原稳态、抗氧化酶和抗 PCD 基因和多种激素，并伴有较低的 PCD 促进基因表达和细胞特征。相反，1000 mg·L ⁻¹ CeO ₂ NPs 通过引起氧化损伤诱导 PCD，并伴有形态负性、质量降低、Ce 积累高、光合作用弱、气孔关闭、脂质过氧化、细胞凋亡、细胞超微结构受损、DNA 碎片、渗透压和氧化还原不稳定性、基因改变和激素波动。总体而言，苜蓿通过控制 PCD 来响应 CeO ₂ NPs 的二元性，而 PCD 受复杂网络的调节。该研究对CeO ₂ 纳米颗粒的合理利用、促进可持续农业、防止纳米材料造成的环境污染提出了新的展望。