Feasibility of using silica (NaSiO and SiONPs) to mitigate mercury in transgenic soybeans grown in contaminated soils and respective effects on nutrient homeostasis.

This study aimed to investigate the potential of Silicon (SiONPs and NaSiO) to mitigate Hg absorption, accumulation, and toxicity in transgenic soybean plants. By analyzing Hg speciation, total Hg content, physiological characteristics, anatomical structures, and the homeostasis of macro (P, S, Ca, K, and Mg) and micro (Cu, Fe, Mn, Zn) nutrients, the impact of Si against Hg-induced stress was assessed. Plants were cultivated under six treatments: water, SiONPs, NaSiO, NaSiO + HgCl, SiONPs + HgCl, and HgCl. The addition of silicon to the soil, both in the form of nanoparticles and in its soluble form, did not negatively impact plant development. SiO NPs reduced Hg concentration in roots by 17% (RR) and 29% (INTACTA) and NaSiO by 15% and 37%. In leaves, Hg reductions were 25% with SiONPs and 22% with NaSiO for RR variety, while INTACTA showed decreases of 14% and 34%. Only Hg(II) species were found, indicating no Hg methylation in soil or plants. PCA revealed that Hg, alone or with Si, altered nutrient absorption. Morphological analyses showed that SiONPs and NaSiO reduced Hg toxicity at the cellular level, highlighting their potential to mitigate heavy metal contamination in crops.