DhTmp1, a Zn(II)2Cys6 Transcription Factor, Negatively Regulates Pathogenicity in Dactylellina haptotyla by Repressing Nematocidal Metabolite Biosynthesis

Fungal pathogenesis and development are regulated by transcription factors. Here, we characterized DhTmp1 in the nematode-trapping fungus Dactylellina haptotyla 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 DhTmp1 deletion upregulated secondary metabolism biosynthetic genes, increasing the abundance of nematocidal metabolites 4-hydroxy benzaldehyde (4-HBA) and 6-chloro-1H-indole-3-carboxaldehyde (6-Cl-ICA), which exhibited potent activity against Meloidogyne incognita and Caenorhabditis elegans, respectively. The 48 h LC50 values for 4-HBA and 6-Cl-ICA against M. incognita and C. elegans values were 29.65 and 92.71 μg/mL, respectively. Furthermore, pot experiments demonstrated that ΔDhTmp1 achieved 74.33% control efficiency against M. incognita compared with the PDB-treated control, outperforming the wild-type strain by ∼20.6%. Our findings reveal that DhTmp1 negatively regulates fungal predation by modulating secondary metabolite synthesis, suggesting that its manipulation could optimize this fungus for the biocontrol of M. incognita.