<i>DhTmp1</i> , a Zn(II) ₂ Cys ₆ Transcription Factor, Negatively Regulates Pathogenicity in <i>Dactylellina haptotyla</i> by Repressing Nematocidal Metabolite Biosynthesis

Fungal pathogenesis and development are regulated by transcription factors. Here, we characterized <i>DhTmp1</i> in the nematode-trapping fungus <i>Dactylellina haptotyla</i> as a negative regulator of predation. Its deletion impaired fungal growth and stress tolerance yet enhanced pathogenicity, while overexpression yielded opposite phenotypes. Integrated transcriptomic and metabolomic analyses revealed that <i>DhTmp1</i> deletion upregulated secondary metabolism biosynthetic genes, increasing the abundance of nematocidal metabolites 4-hydroxy benzaldehyde (4-HBA) and 6-chloro-1<i>H</i>-indole-3-carboxaldehyde (6-Cl-ICA), which exhibited potent activity against <i>Meloidogyne incognita</i> and <i>Caenorhabditis elegans</i>, respectively. The 48 h LC₅₀ values for 4-HBA and 6-Cl-ICA against <i>M. incognita</i> and <i>C. elegans</i> values were 29.65 and 92.71 μg/mL, respectively. Furthermore, pot experiments demonstrated that Δ<i>DhTmp1</i> achieved 74.33% control efficiency against <i>M. incognita</i> compared with the PDB-treated control, outperforming the wild-type strain by ∼20.6%. Our findings reveal that <i>DhTmp1</i> negatively regulates fungal predation by modulating secondary metabolite synthesis, suggesting that its manipulation could optimize this fungus for the biocontrol of <i>M. incognita</i>.