Silicon-coated carbon quantum dots composite nanomaterials mediate pest resistance activation in tobacco (Nicotiana tabacum).

Background: Plant resistance inducers based on nanomaterials (NMs) are a cutting-edge and promising field of interdisciplinary research, focused on developing environmentally and ecologically friendly alternatives for protecting crops. Studies have shown that NMs composed of silicon (SiO) and carbon quantum dots (CDs) can help plants better withstand various environmental and pest-related stresses.

Results: We synthesized and characterized SiO-coated CDs (SiO@CDs) NMs that were found to be absorbed by tobacco leaves. Our research demonstrated that spraying tobacco leaves with a solution containing 100 mg/L SiO@CDs was more effective in promoting plant growth and controlling pest populations, specifically adult aphids compared to using either CDs or SiO alone at the same concentration. The group treated with SiO@CDs achieved a significant 71% mortality of adult aphids after just 7 days, which was significantly different from the control group. Mechanistically, SiO@CDs enhanced both the plant's physical resistance by utilizing Si, and stimulated the production of chemical defense compounds (such as salicylic acid), thereby improving aphid resistance. Additionally, the application of SiO@CDs significantly reduced oxidative stress in the leaves caused by aphid infestation, bolstered the activity of antioxidant enzymes like superoxide dismutase and peroxidase, and reduced malondialdehyde accumulation. Our biosafety experiments indicated that the SiO@CDs were less toxic and safer for non-target organisms in the environment, as well as for human cells.

Conclusion: This study demonstrates that SiO@CDs exhibit excellent performance as a multifunctional insecticide in managing aphid-induced plant pest infestations, highlighting their promising and environmentally friendly potential in pest control and agroecosystem optimization.