The transcription factor PdSte12 contributes to Penicillium digitatum virulence during citrus fruit infection

The postharvest pathogen Penicillium digitatum is responsible for green mold decay on citrus fruit causing important economic losses. To examine possible elements involved in fungal pathogenesis/virulence and fungicide resistance, identification and functional characterization of PdSte12, a particular type of C2H2 fungal transcription factor was carried out. PdSte12 was functionally inactivated through homologous recombination. The deletant fungal strains (ΔPdSte12) failed to cause green mold decay on citrus fruit. ΔPdSte12 mutants exhibited reduced growth and impaired conidiogenesis during fungal infection towards citrus fruit. Additionally, PdSte12 was characterized via overexpression transformants, showing higher infectivity rate in a low virulence P. digitatum strain, providing evidence of PdSte12's role in virulence. Moreover, fungicide sensitivity evaluation showed that PdSte12 was not involved in fungicide resistance as other transcription factors are. These results indicate that the PdSte12 transcription factor controls invasive growth and asexual reproduction as the major virulence function.