Nanoparticles are receiving many interests due to their broad efficiency in mitigating environmental stresses. The purpose of this research was to study the potential of selenium-nanoparticles (Se-NPs) to mitigate the adverse effects of salt stress on growth, physiology, and gene expression of Melissa officinalis. The pot experiment was conducted in a factorial based on completely randomized design (CRD) with three Se-NPs concentrations (0, 50, and 100 mg L⁻¹) and four salinity levels (0, 50, 100, and 150 mM NaCl). The foliar spray of Se-NPs improved the growth of M. officinalis plants at different salinity concentrations, from which the most effective was 50 mg L⁻¹. Plant growth decreased by progressing salinity concentration so that the minimum growth was observed at 150 mM NaCl. The Se-NPs improved salt tolerance in M. officinalis by decreasing lipid peroxidation through increased activity of antioxidant enzymes viz. superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX). Furthermore, exposure to Se-NPs enhanced the transcript levels of phenylalanine ammonia-lyase and rosmarinic acid (RA) synthase genes in lemon balm plants under salt conditions. Plants treated with 100 mg L⁻¹ Se-NPs at non-saline conditions revealed the highest RA accumulation. According to the findings, we suggest both 100 mg L⁻¹ Se-NPs to alleviate the adverse effects of salinity on in the M. officinalis, as well as the biosynthesis pathway of RA as a valuable secondary metabolite.

纳米粒子因其在减轻环境压力方面的广泛效率而受到许多关注。本研究的目的是研究硒纳米颗粒 (Se-NPs) 在减轻盐胁迫对Melissa officinalis 的生长、生理和基因表达的不利影响方面的潜力。盆栽实验是在基于完全随机设计 (CRD) 的因子中进行的，具有三个 Se-NPs 浓度（0、50 和 100 mg L ^-1）和四个盐度水平（0、50、100 和 150 mM NaCl） . Se-NPs的叶面喷洒促进了不同盐度浓度下厚朴植物的生长，其中最有效的是50 mg L ^-1. 植物生长随着盐度浓度的增加而降低，因此在 150 mM NaCl 下观察到最小生长。硒纳米粒改善耐盐巴戟通过增加的抗氧化酶活性即降低脂质过氧化反应。超氧化物歧化酶 (SOD)、过氧化氢酶 (CAT) 和过氧化物酶 (POX)。此外，在盐条件下，暴露于 Se-NPs 提高了柠檬香脂植物中苯丙氨酸解氨酶和迷迭香酸 (RA) 合酶基因的转录水平。在非盐水条件下用 100 mg L ^-1 Se-NPs处理的植物显示出最高的 RA 积累。根据调查结果，我们建议均为100毫克的L ^-1硒纳米粒子，以减轻在盐度的不利影响巴戟，以及作为有价值的次级代谢物的 RA 的生物合成途径。