Fig. 1

Septins regulate the formation of melanized microsclerotia. a Colony phenotype of the wild-type strain XS11 and mutants (ΔVdSep3, ΔVdSep4, ΔVdSep5, and ΔVdSep6) on complete medium (CM). Conidial suspension (10⁶ conidia/mL) of each strain was dropped onto a glass slide covered with CM and incubated at 25 °C for 5 days. Bar = 0.28 cm. b Microscopic observation of microsclerotial development at 4, 8, and 12 days of incubation. Bar = 20 μm. c Colony phenotype of the indicated strains on nitrocellulose membrane overlayed on basal medium (BM). Conidial suspension (10⁶ conidia/mL) of each strain was dropped onto the membrane and incubated at 25 °C. Bar = 3 cm. d Melanized areas of the colonies were determined using ImageJ at 35 days of incubation. Error bars represent standard deviations based on three independent replicates. Asterisks indicate significant differences (**, P < 0.01). e Evaluation of relative expression levels of the genes involved in melanin synthesis in V. dahliae via RT-qPCR. The average gene expression values were normalized against the V. dahliae β-tubulin gene. Error bars represent standard deviation based on four independent technical replicates, and the determined ΔΔCt values were shown in the bottom panel (**, P < 0.01)