Efficacious role of silica nanoparticles in improving growth and yield of wheat under drought stress through stress-gene upregulation

Climate change is now evident and severe water shortage due to unpredictable raining season along with extended summers is expected to hamper crop production across the globe. Application of nanoparticle based formulations is one of the most sought after approach that is being explored currently to alleviate drought stress impact on plants. The present study was aimed to evaluate the potential of biosynthesized silica nanoparticles (silica NPs) in improving the drought tolerance of wheat. Four different concentrations of silica NPs (30, 60, 90, and 120 ppm) were used to treat wheat plants grown under two irrigation regimes- 50% soil moisture content (drought) and 100% soil moisture content (well-watered). The induced drought caused a prominent reduction in both - the crop yield and the morphological parameters of the crop. Foliar application of silica NPs at all concentrations, increased the plant's tolerance towards water stress but 60 ppm concentration was found to be most effective amongst all. After treatment with silica NPs at 60 ppm concentration, the plant height increased by 8.28%, spikes per plant by 98%, seeds per spike by 12.4%, and thousand seed weight by 37.5% as compared to the control. Besides this, expression levels of four drought-stress responsive genes-ABC1, Wdhn13, CHP, and EXP2 was also studied. We observed an enhanced expression of all the stress genes after treatment with silica nanoparticles in wheat plants grown under water deficient conditions, clearly supporting the influence of NP treatment at gene/molecular level. In nutshell, we conclude that silica nanoparticles have the potential to significantly ameliorate the negative impact of drought stress by reviving plant growth and modulating gene expression.