In this study, nanoplastic (NPs) at environmentally relevant concentration (0.001% w/w) had no effect on the growth of rice, while significantly elevated the phytotoxicity of As (III) by 9.4–22.8% based on the endpoints of biomass and photosynthesis. Mechanistically, NPs at 0.001% w/w enhanced As accumulation in the rice shoots and roots by 70.9% and 24.5%, respectively. Reasons of this finding can was that (1) the co-exposure with As and NPs significantly decreased abscisic acid content by 16.0% in rice, with subsequent increasing the expression of aquaporin related genes by 2.1- to 2.7-folds as compared with As alone treatment; (2) the presence of NPs significantly inhibited iron plaque formation on rice root surface by 22.5%. We firstly demonstrated that “Trojan horse effect” had no contribution to the enhancement of As accumulation by NPs exposure. Additionally, NPs disrupted the salicylic acid, jasmonic acid, and glutathione metabolism, which subsequently enhancing the oxidation (7.0%) and translocation (37.0%) of As, and reducing arsenic detoxification pathways (e.g., antioxidative system (28.6–37.1%), As vacuolar sequestration (36.1%), and As efflux (18.7%)). Our findings reveal that the combined toxicity of NPs and traditional contaminations should be considered for realistic evaluations of NPs.

中文翻译：

---

纳米塑料对水稻（Oryza sativa L.）砷毒性加剧的机制洞察：植物激素和谷胱甘肽代谢调节

在这项研究中，环境相关浓度（0.001％w/w）的纳米塑料（NP）对水稻的生长没有影响，但根据生物量和终点指标，As（III）的植物毒性显着提高了 9.4-22.8％。光合作用。从机理上讲，0.001% w/w 的 NP 分别使水稻芽和根中砷的积累分别提高了 70.9% 和 24.5%。这一发现的原因可能是（1）与单独使用 As 相比，As 和 NP 的共同暴露显着降低了水稻中的脱落酸含量 16.0%，随后水通道蛋白相关基因的表达量增加了 2.1 至 2.7 倍治疗; (2) NPs的存在显着抑制了水稻根部表面铁斑的形成22.5%。我们首先证明了“特洛伊木马效应”对于NPs暴露对As积累的增强没有贡献。此外，纳米颗粒扰乱了水杨酸、茉莉酸和谷胱甘肽代谢，随后增强了砷的氧化（7.0%）和易位（37.0%），并减少了砷的解毒途径（例如抗氧化系统（28.6-37.1%），作为液泡隔离（36.1%），和作为外流（18.7%）。我们的研究结果表明，对纳米颗粒进行实际评估时应考虑纳米颗粒和传统污染物的综合毒性。