While the antimicrobial activity of silver nanoparticles (AgNPs) is well established, the phytostimulatory and/or phytotoxic influences of AgNPs in closed tissue culture vessels is more controversial, to some extent. This is because numerous research papers have been published that ultimately conclude apparently contradictory results. In this paper, the physiological responses which AgNPs induce are studied in both tobacco micro-shoots and tobacco seedlings via the utilization of a number of morphological, biochemical, and molecular approaches. This report provides direct evidence that AgNPs positively regulate growth response in tobacco via a curtailing of ethylene production and an inhibition of the general ethylene signaling pathway. Tobacco seedlings exposed to media supplemented with high concentrations of AgNPs (150 μg mL⁻¹) were shown to exhibit a hypersensitivity response. However, when compared to the control, tobacco seedlings exposed to sub-lethal concentrations of AgNPs (50 μg mL⁻¹) displayed increased leaf fresh weight and plant height, as well as a 6-fold increase to root length. Inductively coupled plasma mass spectrometry (ICP-MS) confirmed the presence of silver ions (Ag⁺) in AgNP-treated tobacco leaves, and given that silver is known to be a potent inhibitor of ethylene action, this result led us to question whether AgNPs might be inhibiting ethylene receptor expression. Subsequent qRT-PCR testing in tobacco tissue treated with 50 μg mL⁻¹ AgNP revealed a downregulation of ETR1, ERS1, and CTR1, which are all key ethylene signaling genes, as well as a downregulation of an important downstream ethylene-synthesizing gene, ACS2. This clearly established that the increase to root length in response to AgNPs might be occurring via an AgNP-dependent suppression of ethylene signaling genes. Further, gas chromatography analysis confirmed that tobacco planted on media supplemented with sub-lethal concentrations of AgNPs exhibited a reduction of gaseous ethylene production in closed in vitro vessels. Plants exposed to a higher concentration of AgNPs in their media did not show any additional inhibitory effects, with regard to ethylene production. Nonetheless, ultimately, the collective data implies that AgNPs inhibit various aspects of the ethylene signaling pathway, in addition to inhibiting the production of ethylene itself, and both of these inhibitions occur in a dose-dependent manner.

虽然银纳米粒子 (AgNPs) 的抗菌活性已得到充分证实，但在一定程度上，AgNPs 在封闭组织培养容器中的植物刺激和/或植物毒性影响更具争议性。这是因为已发表的大量研究论文最终得出了明显矛盾的结果。在本文中，通过利用许多形态学、生化和分子方法，研究了 AgNPs 在烟草微芽和烟草幼苗中诱导的生理反应。该报告提供了直接证据，表明 AgNPs 通过减少乙烯生产和抑制一般乙烯信号通路积极调节烟草的生长反应。烟草幼苗暴露于添加高浓度 AgNPs (150 μg/mL) 的培养基中^-1 ) 表现出超敏反应。然而，与对照相比，暴露于亚致死浓度的 AgNPs (50 μg mL ^-1 ) 的烟草幼苗显示出增加的叶子鲜重和植物高度，以及增加 6 倍的根长。电感耦合等离子体质谱 (ICP-MS) 证实了银离子 (Ag ⁺ ) 在经过 AgNP 处理的烟叶中的存在，并且鉴于已知银是乙烯作用的有效抑制剂，这一结果使我们质疑 AgNPs可能是抑制乙烯受体表达。随后在用 50 μg mL ^-1 AgNP处理的烟草组织中进行的 qRT-PCR 检测显示ETR1、ERS1和CTR1，它们都是关键的乙烯信号基因，以及重要的下游乙烯合成基因ACS2的下调。这清楚地表明，响应 AgNPs 的根长度增加可能是通过 AgNP 依赖性抑制乙烯信号基因来发生的。此外，气相色谱分析证实，在补充有亚致死浓度的 AgNPs 的培养基上种植的烟草在封闭的体外实验中表现出气体乙烯产量的减少。船只。在其培养基中暴露于更高浓度的 AgNPs 的植物在乙烯生产方面没有表现出任何额外的抑制作用。尽管如此，最终，集体数据表明，除了抑制乙烯本身的产生之外，AgNPs 还抑制乙烯信号通路的各个方面，并且这两种抑制都以剂量依赖性方式发生。