Gold Nanoparticles Modulate Root Architecture and Nutrient Homeostasis During Early Soybean Growth

Abstract This study investigates how gold nanoparticles (AuNPs) influence early growth and nutrient homeostasis in soybean ( Glycine max ), with emphasis on root system architecture and ionomic regulation. Plants were cultivated under controlled conditions and exposed to 160 mg L − 1 citrate-stabilized AuNPs (~ 19 nm). Morphophysiological parameters and elemental profiles were evaluated to assess growth responses and nutrient dynamics. AuNP exposure did not induce visible toxicity but significantly enhanced root branching and elongation, accompanied by increases in fresh biomass (ca. 24% in leaves, 20% in stems, and 33% in roots) and plant height (+ 13%). Gold accumulation was restricted to roots (1.66 mg kg − 1 ), with no detectable translocation to aerial tissues. Ionomic analysis revealed a selective reconfiguration of nutrient homeostasis, including increased Mg (+ 52%) and Fe (+ 17%) in roots, alongside reductions in Zn, Cu, and Mn. Multivariate analysis (PCA – Principal Component Analysis) confirmed distinct ionomic signatures between treated and control plants, primarily driven by root-associated responses. These findings suggest that AuNPs may modulate early plant development through root-centered ionomic reprogramming, potentially involving shifts in nutrient uptake and redox-related processes. The combined enhancement of root architecture and biomass, despite minimal nanoparticle accumulation, is consistent with a hormesis-like response under the tested conditions. Rather than establishing agronomic applicability, this work provides a hypothesis-generating framework linking nanoparticle exposure to coordinated changes in nutrient balance and growth regulation in plants.