Species-specific modulation of nitro-oxidative stress and root growth in monocots by silica nanoparticle pretreatment under copper oxide nanoparticle stress.

Background: Abiotic stressors such as heavy metals and nanoparticles pose significant challenges to sustainable agriculture, with copper oxide nanoparticles (CuO NPs) known to inhibit root growth and induce oxidative stress in plants. While silica nanoparticles (SiO₂ NPs) have been shown to increase abiotic stress tolerance, their role in mitigating CuO NP-induced stress in crops, especially monocots, remains poorly understood. This study addresses this critical knowledge gap by investigating how SiO₂ NP pretreatment modulates CuO NP-induced stress responses, with a particular focus on root growth inhibition and nitro-oxidative stress pathways.

Results: Using an in vitro semihydroponic system, seeds were pretreated with varying concentrations of SiO₂ NPs (100-800 mg/L) before exposure to CuO NPs at levels known to inhibit root growth by 50%. SiO₂ NP pretreatment alleviated CuO NP-induced root growth inhibition in sorghum, wheat, and rye but intensified it in triticale. These responses are associated with species-specific alterations in reactive signaling molecules, including a reduction in nitric oxide levels and an increase in hydrogen sulfide in sorghum, a decrease in superoxide anion levels in rye, and elevated hydrogen peroxide levels in wheat. Protein tyrosine nitration, a marker of nitro-oxidative stress, was reduced in most cases, further indicating the stress-mitigating role of SiO₂ NPs. These signaling molecules were selected for their established roles in mediating oxidative and nitrosative stress responses under abiotic stress conditions.

Conclusions: SiO₂ NP pretreatment modulates CuO NP-induced stress responses through species-specific regulation of reactive oxygen and nitrogen species, demonstrating its potential as a tool for enhancing crop resilience. These findings advance the understanding of nanoparticle‒plant interactions and provide a foundation for future applications of nanotechnology in sustainable agriculture.

Clinical trial number: Not applicable.