2-Hydroxy-4-methoxybenzaldehyde (HMB) disrupts ergosterol biosynthesis, redox metabolism, and DON biosynthesis of Fusarium graminearum revealed by transcriptome analysis

The phytopathogenic fungus <i>Fusarium graminearum</i> causes Fusarium head blight, which threatens agricultural yield and human health. We previously demonstrated that a plant-derived natural compound, 2-hydroxy-4-methoxybenzaldehyde (HMB), can inhibit <i>F. graminearum</i>. This study continued to investigate its antifungal mechanism. Compared to the control, HMB treatment at the minimum inhibitory concentration (MIC) significantly reduced ergosterol levels by 61.78%, indicating compromised fungal membrane integrity. Concurrently, intracellular reactive oxygen species (ROS) levels increased 22-fold, accompanied by a 146.03% increase in hydrogen peroxide (H₂O₂) content. Meanwhile, superoxide dismutase (SOD) activity increased, while catalase (CAT) activity declined, suggesting a marked change of redox metabolism upon HMB exposure. In addition, Quantitative Real-time PCR (qRT-PCR) analysis revealed that HMB treatment significantly regulated the expression of genes participating in ergosterol biosynthesis (<i>Erg2</i>, <i>Erg5</i>, <i>Erg6</i>, etc.), DON biosynthesis (up to 16 genes), the redox system (<i>MnSOD</i>, <i>Cu/ZnSOD</i>, <i>GSS</i>, and <i>CAT</i>), global regulators (<i>LaeA</i>, <i>VeA</i>, and <i>VelB</i>), and stress signaling pathways (<i>Hog1</i>, <i>Ssk1</i>, <i>Ssk2</i>, and <i>Pbs2</i>). These findings revealed the in-depth antifungal mechanism of HMB and proposed that HMB holds potential as an antifungal agent.