Boosting Rice Resilience: Role of Biogenic Nanosilica in Reducing Arsenic Toxicity and Defending against Herbivore

The use of nanoparticles is a promising ecofriendly strategy for mitigating both abiotic and biotic stresses. However, the physiological and defense response mechanisms of plants exposed to multiple stresses remain largely unexplored. Herein, we examined how foliar application of biogenic nanosilica (BNS) impacts rice plant growth, molecular defenses, and metabolic responses when subjected to arsenic (As) toxicity and infested by the insect <i>Chilo suppressalis</i>. We show that BNS significantly increased shoot and root silicon accumulation but reduced the shoot As content by 34.7% under herbivory. Additionally, BNS reduced <i>C. suppressalis</i> larval weight gain by 34.5 and 12.3% without and with As stress, respectively. Importantly, BNS enhanced antioxidant enzyme activity under As stress, herbivore attack, and combined pressures, surpassing the effects of traditional silicate fertilizers. BNS ultimately increased rice shoot biomass by 8.2-23.4% under the respective stress conditions compared to the control treatment. Moreover, while As stress alone diminished the plant's resistance to herbivores, BNS application countered this effect by increasing detoxifying compound (e.g., glutathione) production and antioxidant enzyme activity. This study highlights the impact of biotic and abiotic stress interactions on BNS-enhanced plant resilience mechanisms in rice plants, reallocating resources to counter heavy metal toxicity and herbivore damage in agroecosystems.