Assays of the role of VdGAL4 in the normal vegetative growth and conidial production of V. dahliae. (A) Colony morphology of WT, ΔVdGAL4, and C-ΔVdGAL4 strains in PDA at 25°C for 14 days. (B) Morphology of the conidia of all tested strains under scanning electron microscope. Bar, 5 μm. (C) Growth diameter of all tested strains shown in panel A. (D) The conidial production of all tested strains after 5 days on Czapek-Dox medium. (E) Conidial germination rate of all tested strains. (F) Mycelium morphology of all tested strains under light microscope. Bar, 200 μm. The error bar represents standard error of the mean. *, P < 0.05; **, P < 0.01.