Silicon-mediated abiotic and biotic stress mitigation in plants: Underlying mechanisms and potential for stress resilient agriculture.

Silicon (Si) is a beneficial macronutrient for plants. The Si supplementation to growth media mitigates abiotic and biotic stresses by regulating several physiological, biochemical and molecular mechanisms. The uptake of Si from the soil by root cells and subsequent transport are facilitated by Lsi1 (Low silicon1) belonging to nodulin 26-like major intrinsic protein (NIP) subfamily of aquaporin protein family, and Lsi2 (Low silicon 2) belonging to putative anion transporters, respectively. The soluble Si in the cytosol enhances the production of jasmonic acid, enzymatic and non-enzymatic antioxidants, secondary metabolites and induces expression of genes in plants under stress conditions. Silicon has been found beneficial in conferring tolerance against biotic and abiotic stresses by scavenging the reactive oxygen species (ROS) and regulation of different metabolic pathways. In the present review, Si transporters identified in various plant species and mechanisms of Si-mediated abiotic and biotic stress tolerance have been presented. In addition, role of Si in regulating gene expression under various abiotic and biotic stresses as revealed by transcriptome level studies has been discussed. This provides a deeper understanding of various mechanisms of Si-mediated stress tolerance in plants and may help in devising strategies for stress resilient agriculture.