Silicon Nanoparticles and Apoplastic Protein Interaction: A Hypothesized Mechanism for Modulating Plant Growth and Immunity.

Silicon nanoparticles (SiNPs) have emerged as multifunctional tools in sustainable agriculture, demonstrating significant efficacy in promoting crop growth and enhancing plant resilience against diverse biotic and abiotic stresses. Although their ability to strengthen antioxidant defense systems and activate systemic immune responses is well documented, the fundamental mechanisms driving these benefits remain unclear. This review synthesizes emerging evidence to propose an innovative paradigm: SiNPs remodel plant redox signaling networks and stress adaptation mechanisms by forming protein coronas through apoplastic protein adsorption. We hypothesize that extracellular SiNPs may elevate apoplastic reactive oxygen species (ROS) levels by adsorbing and inhibiting antioxidant enzymes, thereby enhancing intracellular redox buffering capacity and activating salicylic acid (SA)-dependent defense pathways. Conversely, smaller SiNPs infiltrating symplastic compartments risk oxidative damage due to direct suppression of cytoplasmic antioxidant systems. Additionally, SiNPs may indirectly influence heavy metal transporter activity through redox state regulation and broadly modulate plant physiological functions via transcription factor regulatory networks. Critical knowledge gaps persist regarding the dynamic composition of protein coronas under varying environmental conditions and their transgenerational impacts. By integrating existing mechanisms of SiNPs, this review provides insights and potential strategies for developing novel agrochemicals and stress-resistant crops.