Para-dichlorobenzene inhibits Fusarium oxysporum f. sp. cubense tropical race 4 by inducing membrane damage, mitochondrial dysfunction, and transcriptional reprogramming

Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), the causal agent of Fusarium wilt, poses a serious threat to global banana and plantain production. This study investigated the toxicological impact of 1,4-dichlorobenzene (p-DCB), a halogenated aromatic compound from biocontrol bacteria Streptomyces misionensis TF78, on the virulent Foc TR4 strain, combining morphological and transcriptomic analyses. Fungal mycelia were exposed to 2.67 g/L p-DCB for 12, 48, and 96 h, separately, after which structural alterations and gene expression changes were evaluated. Genome-wide transcriptional profiles were characterized using RNA sequencing, and 20 differentially expressed genes (DEGs) were validated through quantitative real-time PCR (qRT-PCR). The results demonstrated that p-DCB treatment significantly (p < 0.01) reduced the colony growth diameter of Foc TR4 and caused severe mycelial damage, structural ablation, a significant decrease in spore germination rates (p < 0.01), and a 38–62% increase in electrolyte leakage compared to the control, indicating severe membrane disruption. A total of 6,411, 5,696, and 3,981 DEGs were identified at 12, 48, and 96 h after p-DCB treatment, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated enrichment of endoplasmic reticulum and glycosylation pathways linked to membrane remodeling and mitochondrial dysfunction. Notably, genes encoding ATP synthase and electron transport chain complexes, including NADH: ubiquinone oxidoreductase, ubiquinol: cytochrome c reductase, and cytochrome c oxidase, were significantly (fold change ≥ 4, p < 0.01) upregulated. In sterol biosynthesis, most genes (ERG25, ERG26, ERG6) were upregulated, while ERG8 was downregulated. This study provides a comprehensive overview of altered sterol biosynthesis, oxidative stress accumulation, lipid remodeling, and membrane damage in Foc TR4 under p-DCB-induced stress. These findings establish p-DCB as a membrane-targeting antifungal compound and highlight molecular targets that may inform improved disease management strategies.