Silencing the SL-biosynthetic genes GbCCD7 and GbCCD8b reduced resistance to V. dahliae in cotton. A and B) Expression of GbCCD7 and GbCCD8b in roots of GbCCD7-silenced (TRV:GbCCD7) and GbCCD8b-silenced (TRV:GbCCD8b) Hai7124 cotton plants. Data are means ± SD of three biological replicates (n = 3; three independent plants/biological replicate). The expression value of TRV:00 was normalized as 1. Asterisks indicate statistically significant differences between TRV:00 and TRV:GbCCD7 or TRV:GbCCD8b plants as determined by a Student's t-test (**P < 0.01). C and D) Representative pictures of O. aegyptiaca seed germination (C) and germination percentages (D) under the treatments with the extracts from roots of TRV:00 (control), TRV:GbCCD7, and TRV:GbCCD8b plants. Bar = 5 mm. Data are means ± SD of three biological replicates (n = 3; ≥30 seeds/biological replicate). E) Albino phenotype of the cotton plants inoculated with TRV:GbCLA vector after 14 d. F) Disease symptoms of TRV:00, TRV:GbCCD7, and TRV:GbCCD8b seedlings at 21 dpi with V. dahliae. G–J) Disease indices (G), stem anatomy (H), lesion area percentages (I), and fungal renewal cultivation levels (J) in TRV:00, TRV:GbCCD7, and TRV:GbCCD8b cotton plants shown in (F). Bar = 2 mm (stem anatomy), Bar = 2 cm (fungal renewal cultivation). Data are means ± SD of three biological replicates (n = 3; ≥25 stem cuttings/biological replicate). Different letters indicate statistical differences among different genotypes as determined by a one-way ANOVA analysis using the Tukey's HSD test (P < 0.05). dpi, day-post-inoculation.