Zinc-loaded mesoporous silica nanoparticles mitigate salinity stress in wheat seedlings through silica-zinc uptake, osmotic balance, and ROS detoxification

Abiotic stresses like salinity and micronutrient deficiency majorly affect wheat productivity. Applying mesoporous silica nanoparticles (MSiNPs) as a smart micronutrient delivery system can facilitate better stress management and nutrient delivery in this context. In this purview, we investigated the potential of MSiNPs and Zn-loaded MSiNPs (Zn-MSiNPs) on the growth and physiology of wheat seedlings exposed to salinity stress (200 mM NaCl). Initially, the FESEM, DLS, and BET analysis portrayed nanoparticles' spherical shape, nano-size, and negatively charged mesoporous surface. A sustained release of Zn+2 from Zn-MSiNPs at 30 °C, diffused light, and pH 7 was perceived with a 96.57% release after 10 days. Further, the mitigation of NaCl stress in the wheat seedlings was evaluated with two different concentrations, each of MSiNPs and Zn-MSiNPs (1 g/L and 5 g/L), respectively. A meticulous improvement in the germination and growth of wheat seedlings was observed when treated with both MSiNPs and Zn-MSiNPs. A considerable increase in chlorophyll, total protein, and sugar content was in consort with a substantial decline in MDA, electrolyte leakage, and ROS accumulation, showcasing the nanomaterials' palliating effects. Most importantly, the K+/Na+ ratio in shoots increased significantly by 3.43 and 4.37 folds after being treated with 5 g/L Zn-MSiNPs, compared to their respective control sets (0 and 200 mM NaCl). Therefore, it can be concluded that the Zn-MSiNPs can effectively restrain the effects of salinity stress on wheat seedlings.