GATA-type transcription factor MaNsdD regulates host cuticle penetration in Metarhizium acridum via a CAP gene MaCap2

NsdD is a well-established transcription factor regulating conidiation in filamentous fungi. Although NsdD has been implicated in the virulence of pathogenic fungi, its underlying molecular mechanisms remain elusive.

The median lethal time of the NsdD deletion mutant (ΔMaNsdD) was notably extended by 3.078 ± 0.004 days compared to the wild-type (WT) after topical inoculation. In contrast, intrahemocoel injection assays showed no significant virulence defect in ΔMaNsdD, indicating that ΔMaNsdD is more impaired in host penetration than in causing systemic infection. Further experiments demonstrated that the reduced penetration ability in ΔMaNsdD stems from a severe lack of intracellular lipid droplets and glycerol, which ultimately decreases appressorial turgor pressure. Transcriptomic analysis revealed that MaNsdD influences the phenylalanine pathway and affects the expression of many virulence-related genes. Among the differentially expressed genes, we identified a CAP family gene, MaCap2. Deleting MaCap2 significantly reduced fungal virulence due to impaired penetration ability. Additional validation through quantitative polymerase chain reaction (qPCR), yeast one-hybrid, and electrophoretic mobility shift assays confirmed that MaNsdD directly binds to the MaCap2 promoter and regulates its expression, establishing MaCap2 as a direct downstream target in the MaNsdD-controlled network that regulates virulence.

Our findings demonstrate that MaNsdD promotes host cuticle penetration in Metarhizium acridum through regulating MaCap2 expression. © 2025 Society of Chemical Industry.