Silicon Immunity to Nematodes: Indication of Primary Defence Mechanisms in Phytonematodes Interactions

Abstract

Reduction of global crop losses due to plant-parasitic nematodes (PPNs) has been achieved by executing numerous efficient management tactics. One such strategy is the addition of silicon (Si), which is known to increase plant resistance to nematodes. Si is an efficient plant growth regulator and governs various defense mechanisms in plant-nematode interactions. Genes encoding aquaporin-type channels like nodulin 26-like intrinsic protein (NIPs) and silicon transporters (Lsi1, Lsi2, Lsi3, and Lsi6) encourage the uptake of silicic acid by plant roots. These processes include the creation of a physical barrier, activating enzymes related to defense, synthesis of antimicrobial compounds, and transcriptional regulation of defense genes. Avoiding nematode proliferation, gall formation, and disease severity has been shown with Si-based chemicals including SiO₂, SiO₂NPs, nano-chelated Si fertilizer, sodium silicate, and sodium metasilicate. It has been proven that Si buildup in epidermal tissue may be responsible for the reinforcement of plant resistance to nematode infection. It acts as a pre-formed defense barrier before nematode penetration, hence inducing resistance against various nematodes. It is known that Si taken by plants forms a binary coating at the epidermal cell wall, strengthening the cell wall and fighting against nematode infections. This element resulted in the formation of a thick layer beneath the cuticle, which decreased the cell wall's susceptibility to nematode enzymatic breakdown and reduced nematode infection in agricultural and horticultural crops by acting as a physical barrier on plant tissues. This review emphasizes in detail the physical, biochemical, and molecular mechanisms involved in plant-nematode interactions to gain a better understanding of what way Si contributes to these protective effects. Furthermore, this analysis seeks to evaluate the necessity of Si-based approaches for better plant-nematode disease management as well as the possibility of Si applications to strengthen plant resistance against nematodes sustainably.