FIG 4.

Deletion of VdMRTF1 in Verticillium dahliae increases its virulence on tobacco seedlings. (A) 1-month-old tobacco seedlings (Nicotiana benthamiana) were inoculated and incubated for 10 min with a 10⁶-conidium/mL suspension of the wild-type VdLs.17, ΔVdMRTF1, and ΔVdMRTF1-C strains. Controls (CK) were mock-inoculated with distilled water. Disease symptoms of tobacco seedlings were photographed at 15 dpi. (B) Disease symptoms of tobacco seedlings were photographed at 35 dpi. (C) Disease symptoms of tobacco seedlings were scored visually on a scale from 0 to 4 at 15 dpi and 35 dpi (0 represents no symptoms, 1 represents one third of leaves with chlorosis or wilting, 2 represents one half leaves with chlorosis or wilting, 3 represents two thirds of leaves with chlorosis or wilting, and 4 represents more than 85% leaves with chlorosis or wilting). The results were based on three independent replicates. Asterisks indicate significant differences (**P < 0.01). (D) Line chart showing the disease index of tobacco seedlings inoculated with wild-type VdLs.17, ΔVdMRTF1, and ΔVdMRTF1-C strains. The results were based on three independent replicates. Error bars represent the standard deviations based on three independent replicates. Asterisks indicate significant differences (**P < 0.01).