Abstract：
Melatonin (Mel) is a phytohormone that plays a crucial role in various plant processes, including stress response. Despite numerous studies on the role of Mel in stress resistance, its significance in plants exposed to benzalkonium chloride (BAC) pollution remains unexplored. BAC, a common antiseptic, poses a threat to terrestrial plants due to its widespread use and inefficient removal, leading to elevated concentrations in the environment. This study investigated the impact of BAC (0.5 mg L-1) pollution on wild-type Col-0 and snat2 knockout mutant Arabidopsis lines, revealing reduced growth, altered water relations, and gas exchange parameters. On the other hand, exogenous Mel (100 μM) treatments mitigated BAC-induced phytotoxicity and increased the growth rate by 1.8-fold in Col-0 and 2-fold in snat2 plants. snat2 mutant seedlings had a suppressed carbon assimilation rate (A) under normal conditions, but BAC contamination led to further A repression by 71% and 48% in Col-0 and snat2 leaves, respectively. However, Mel treatment on stressed plants was successful in improving Fv/Fm and increased the total photosynthesis efficiency by regulating photochemical reactions. Excessive H2O2 accumulation in the guard cells of plants exposed to BAC pollution was detected by confocal microscopy. Mel treatments triggered almost all antioxidant enzyme activities (except POX) in both Arabidopsis lines under stress. This enhanced antioxidant activity, facilitated by foliar Mel application, contributed to the alleviation of oxidative damage, regulation of photosynthesis reactions, and promotion of plant growth in Arabidopsis. In addition to corroborating results observed in many agricultural plants regarding the development of tolerance to environmental stresses, this study provides novel insights into the action mechanisms of Mel under the emerging pollutant benzalkonium chloride.
摘要：
褪黑素（Mel）是一种植物激素，在各种植物过程中起着至关重要的作用，包括应激反应。尽管大量研究了梅尔在抗应激中的作用，其在暴露于苯扎氯铵（BAC）污染的植物中的重要性仍未被探索。BAC,一种常见的防腐剂,由于其广泛使用和低效去除，对陆地植物构成威胁，导致环境中浓度升高。本研究调查了BAC（0.5mgL-1）污染对野生型Col-0和snat2敲除突变拟南芥系的影响，揭示增长减少，改变了水的关系，和气体交换参数。另一方面,外源Mel（100μM）处理减轻了BAC诱导的植物毒性，并使Col-0和snat2植物的生长速率提高了1.8倍。在正常条件下，snat2突变体幼苗的碳同化率（A）受到抑制，但是BAC污染导致Col-0和Snat2叶片中进一步的A抑制分别为71％和48％，分别。然而,对胁迫植物的Mel处理成功地改善了Fv/Fm，并通过调节光化学反应提高了总光合作用效率。通过共聚焦显微镜检测到暴露于BAC污染的植物的保卫细胞中过量的H2O2积累。在胁迫下，Mel处理触发了两个拟南芥品系中几乎所有的抗氧化酶活性（POX除外）。这种增强的抗氧化活性，通过叶面梅尔应用促进，有助于减轻氧化损伤，光合作用反应的调节，和促进拟南芥的植物生长。除了在许多农业植物中观察到的关于对环境压力的耐受性发展的确证结果之外，这项研究为新兴污染物苯扎氯铵下Mel的作用机制提供了新的见解。
