Standard chemical toxicity testing guidelines using aquatic plant Lemna minor have been developed by several international standardisation organisations. Although being highly useful for regulatory purposes by focusing on traditional adverse endpoints, these tests provide limited information about the toxic mechanisms and modes of action (MoA). The present study aimed to use selected functional assays in L. minor after exposure to 3,5-dichlorophenol (3,5-DCP) as a model to characterise the toxic mechanisms causing growth inhibition and lethality in primary producers. The results demonstrated that 3,5-DCP caused concentration-dependent effects in chloroplasts and mitochondria. Uncoupling of oxidative phosphorylation (OXPHOS), reduction in chlorophyll (Chlorophyll a and b) content, reproduction rate and frond size were the most sensitive endpoints, followed by formation of reactive oxygen species (ROS), lipid peroxidation (LPO), reduction of carotenoid content and impairment of photosynthesis efficiency. Suppression of photosystem II (PSII) efficiency, electron transport rate (ETR), chlorophyll (a and b) contents and oxidative phosphorylation (OXPHOS) were closely correlated while ROS production and LPO were negative correlated with ETR, carotenoid content and growth parameters. A network of conceptual Adverse Outcome Pathways (AOPs) was developed to decipher the causal relationships between molecular, cellular, and apical adverse effects occurring in L. minor to form a basis for future studies with similar compounds.

几个国际标准化组织已经制定了使用水生植物Lemna minor的标准化学毒性测试指南。尽管这些测试通过关注传统的不良终点而对监管目的非常有用，但是这些测试提供的有关毒性机制和作用方式（MoA）的信息有限。本研究的目的是在暴露于3,5-二氯苯酚（3,5-DCP）后，在小L. L.中使用选定的功能测定法作为模型，以表征引起初级生产者生长抑制和致死性的毒性机制。结果表明3,5-DCP在叶绿体和线粒体中引起浓度依赖性作用。氧化磷酸化（OXPHOS）的解偶联，叶绿素（叶绿素a的减少）和b）的含量，再现速率和藻体尺寸是最敏感的端点，接着形成反应性氧物质（ROS），脂质过氧化（LPO），还原的类胡萝卜素含量和光合效率受损。抑制光系统II（PSII）的效率，电子传输速率（ETR），叶绿素（a和b）含量和氧化磷酸化（OXPHOS）密切相关，而ROS生成和LPO与ETR，类胡萝卜素含量和生长参数负相关。开发了概念性不良结果途径（AOP）网络，以解释在小L. L.中发生的分子，细胞和顶端不良反应之间的因果关系 为类似化合物的未来研究奠定基础。