Multifunctional Biochar Derived N-Doped Carbon Quantum Dots Induce Mitochondrial Dysfunction and Disrupt Energy Metabolism in Meloidogyne incognita

Given the increasing global threat of Meloidogyne incognita to crops coupled with the environmental and health risks associated with synthetic nematicides, current findings investigate a biochar-derived nanomaterial strategy that affects the energy metabolism of M. incognita. Carbon quantum dots (CQDs) derived from rice husk biochar (B-CQDs) were used to develop multifunctional nitrogen-doped CQDs (B-N@CQDs) as a sustainable nanonematicide. Among both undoped and N-doped CQDs, B-N@CQDs3 (300 μg/mL) exhibited nematocidal activity and significantly disrupted the physiological functions of M. incognita, achieving 68.4% mortality and suppressed key parasitic traits including locomotion, root penetration, and egg hatching. Mechanistic investigations revealed that B-N@CQDs3 induced pronounced oxidative stress in M. incognita leading to mitochondrial dysfunction, substantial ATP depletion up to 48.2%, and accumulation of lipofuscin in M. incognita juveniles (J₂). Transcriptome profiling further demonstrated broad disruption of genes associated with oxidative phosphorylation and fatty acid degradation, indicating the systemic impairment of bioenergetic pathways. To our knowledge, this is the first report demonstrating that B-N@CQDs3 specifically targets mitochondrial functioning and impacts fatty acid degradation pathways in M. incognita. In the greenhouse assay, soil application of B-N@CQDs3 significantly reduced nematode infection while improving plant growth and triggered antioxidant enzymes in tomatoes. Collectively, these findings establish B-N@CQDs a mitochondria-targeting nanonematicide capable of altering metabolic pathways in M. incognita. This work highlights the potential of sustainable biochar-derived carbon nanomaterials as a precision tool for next-generation eco-friendly plant protection.