Transcriptomic and physiological evidence for magnolol antifungal activity against fusarium oxysporum f. sp. cubense tropical race 4.

Banana Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense Tropical Race 4 (Foc TR4), ranks among the most devastating soil-borne fungal diseases. Prolonged use of single-target fungicides can lead to environmental contamination, resistance evolution, and limited efficacy due to the narrow range of target sites. Therefore, discovering an environmentally friendly fungicide with a novel mechanism of action and multiple targets is crucial for achieving sustainable disease management of banana Fusarium wilt. In this study, six plant-derived compounds were screened for antifungal activity, identifying magnolol (MAG) as the most effective inhibitor, with an EC50 value of 18.17 μg·mL-1. MAG significantly suppressed mycelial growth and conidial germination in vitro and markedly reduced disease incidence and severity in banana seedlings. Integrated transcriptomic and physiological analyses revealed that MAG disrupts membrane integrity, redox homeostasis, and energy metabolism, accompanied by suppression of RNA processing and ribosome biogenesis. Ultrastructural damage, membrane depolarization, and the study of antioxidant enzyme activity further confirmed the severe membrane disruption and the induction of ROS accumulation. Moreover, MAG exhibited broad-spectrum antifungal activity against multiple Fusarium oxysporum formae speciales and Foc races. Collectively, these findings highlight the multi-target antifungal mechanism of MAG, positioning it as a promising and eco-friendly candidate for controlling banana Fusarium wilt, offering a sustainable alternative to conventional chemical treatments. The broad-spectrum activity and low toxicity of MAG make it a potentially key component in future disease management strategies, particularly in reducing pesticide dependence and environmental pollution.