Silica nanoparticles enhanced seed germination and seedling growth of drought-stressed wheat by modulating antioxidant enzymes and mitigating lipid peroxidation†

Drought imposes severe constraints on wheat production, especially when stress occurs at the seedling stage. Silica nanoparticles (SiNPs) could alleviate drought stress; however, their precise regulation mechanism in wheat remains largely unknown. This study examined the biological effects of SiNP200 (200 mg L⁻¹ SiNPs) on drought-stressed seeds and seedlings. Under drought stress, SiNP200 enhanced the germination rate, potential, radical length, and shoot length. Further analysis showed that SiNP200 upregulated the expression of TaSOD, TaAPX, TaPOD, TaP5CS, and TaSWEET, thereby activating antioxidant enzymes, including superoxide dismutase, peroxide dismutase, and ascorbate, while also promoting the synthesis of osmotic regulators such as proline and soluble sugars. Notably, a decrease in MDA content was observed, and Schiff reagent and Evans blue staining confirmed that SiNP200 mitigated lipid peroxidation and improved plasma membrane integrity in drought-stressed wheat. These findings highlight the pivotal role of SiNP200 in enhancing wheat drought tolerance through the activation of ROS scavenging systems, reduction of lipid peroxidation, and alleviation of osmotic stress. This study demonstrated that SiNPs can enhance wheat seed germination and seedling development under drought stress, thereby providing a theoretical basis for the application of SiNP-based fertilizers.