ABSTRACT
Silicon (Si) is considered as a quasi-essential element for the plant system, but its beneficial effects on growth and stress tolerance have been recorded in a wide variety of agricultural and horticultural crops. However, Si-mediated molecular regulation of physiological processes by the mediation of gene expression, particularly under stressed conditions, has been dealt with in a limited number of plants. Similarly, the prophylactic mechanism of Si against several pathogen attacks has been attributed to the secondary metabolism in plants. Silicon triggers vital secondary metabolite biosynthetic pathways such as the phenylpropanoid and terpenoid pathways for the accumulation of antimicrobial compounds or phytoalexins. In this chapter, the Si-mediated regulations of genes and secondary metabolites under abiotic and biotic stress are discussed.
