Small-sized graphene oxide/Chelidonium majus nanocomposite: A potent antifungal agent against plant pathogenic fungi

Plant diseases present a severe threat to global agricultural productivity and ecological stability, driving the need for effective and environmentally benign antifungal agents. However, conventional synthetic fungicides raise concerns about resistance and non-target toxicity, prompting exploration of plant-derived alternatives. In this study, we developed a nanocomposite system (Cmce-SGO) by integrating Chelidonium majus crude extract (Cmce) with small-sized graphene oxide (SGO). The optimized formulations exhibited pronounced synergistic activity against Fusarium graminearum ( FG ), Fusarium oxysporum ( FO ) and Corynespora cassiicola ( CC ), with EC 50 values of 1190 ppm (1.19 mg·mL −1 ), 2030 ppm (2.03 mg·mL −1 ), and 750 ppm (0.75 mg·mL −1 ), respectively—representing 11.5–34.8% improvement over the extract alone. Mechanistic investigations revealed that the antifungal action involves disruption of mycelial morphology, impairment of cell membrane integrity, and induction of intracellular macromolecule leakage, as substantiated by transcriptomic analyses. Pot experiments demonstrated that Cmce-SGO achieved 85.7% control efficacy against cucumber Fusarium wilt, significantly outperforming Cmce (71.4%) and SGO (14.3%). Comprehensive biosafety assessments showed no phytotoxicity to cucumber seedlings and low acute toxicity to zebrafish (LC 50 > 19 mg·mL −1 , with a safety margin exceeding 10-fold relative to effective concentrations. By integrating a renewable botanical extract with a multifunctional carbon nanocarrier, this work establishes a multi-target, low-toxicity nano-fungicide that offers a sustainable and complementary alternative to conventional synthetic pesticides for integrated crop protection.