Virus-induced RNA silencing of a mitochondrial carrier reduces the virulence of a vascular wilt fungus in tomato

: Verticillium dahliae, the causal agent of Verticillium wilt, is among the most destructive vascular pathogens of crops worldwide. Despite its economic relevance, the molecular foundations of its pathogenicity remain only partially understood. Here, we investigated the role of VdFOW1 (VDAG_03947), a mitochondrial carrier gene encoding a YHM2-like transporter homologous to Fusarium oxysporum FOW1, which has previously been demonstrated to be essential for virulence. By employing a Tobacco mosaic virus-based virus-induced gene silencing (VIGS) system, we generated VdFOW1-silenced mutants in both defoliating (V323) and non-defoliating (V10) isolates of V. dahliae. Silencing led to a pronounced decrease in VdFOW1 transcript accumulation, without affecting fungal growth, hyphal morphology, or conidiation. However, when tested on tomato plants, the silenced isolates exhibited a striking reduction in disease severity compared to the wild-type and control strains. These results identify VdFOW1 as a pivotal determinant of V. dahliae virulence and suggest that mitochondrial metabolism plays a conserved and critical role in vascular wilt pathogenesis. Beyond its mechanistic insight, this work establishes the feasibility of RNA-based functional tools for probing and potentially mitigating fungal diseases.