Integrated transcriptomic and metabolomic analysis reveals zinc oxide nanoparticles associated modulation of salt stress responses in Glycyrrhiza uralensis

The depletion of wild <i>Glycyrrhiza</i> resources has made artificial cultivation essential; however, soil salinization severely limits the yield and quality of <i>G. uralensis</i>. Zinc oxide nanoparticles (ZnO NPs) exhibit promising potential in phytoremediation, yet their regulatory mechanisms under salt stress remain unclear. In this study, <i>Glycyrrhiza uralensis</i> was used to investigate the effects of salt stress and the modulating effects of ZnO NPs. Our results showed that ZnO NPs application enhanced salt accumulation in <i>Glycyrrhiza uralensis</i> while maintaining photosynthetic performance and root growth. Integrated transcriptomic and metabolomic analyses revealed that salt stress disrupted phenylpropanoid and flavonoid biosynthesis pathways, leading to detectable alterations in root metabolic profiles. Moreover, ZnO NPs modulated root metabolite accumulation and related gene expression, which further affected root metabolites and activated plant defense systems, contributing to enhanced root system adaptation and overall plant resilience under salt stress. These findings suggest that ZnO NPs treatment is associated with improved salt stress performance in <i>G. uralensis</i> under the present experimental conditions. This study provides insights into the potential application of ZnO nanoparticles in improving salt tolerance, thereby offering a promising strategy for the sustainable cultivation of <i>Glycyrrhiza uralensis</i> in saline-alkali soils.