Fig. 9

WRKY1 can also promote SA biosynthesis by positively regulating the EPS1 gene to defend against PM. A Observations of the overall powdery mildew lesions on leaf surfaces were made 7 days after PM inoculation. Subsequently, leaves were stained with trypan blue and examined for spores and mycelia using a super-depth stereomicroscope. Ri-WRKY1 represents RNAi-silenced WRKY1 plants, OE-WRKY1 represents WRKY1-overexpressing plants, and EV represents empty vector control plants. Black and white scale bars represent 1 cm and 1 mm, respectively. B Spore counts and leaf area measurements were taken for all leaves of the entire plant 7 days after PM inoculation to calculate spore density per unit leaf area. C Endogenous SA content in WRKY1-silenced and overexpressing lines. D The position of the W-box element in the promoter and its mutated sequence are displayed. Y1H analysis indicates that WRKY1 specifically binds to the W-box element of the EPS1 promoter. Selection medium contains SD/-Leu medium supplemented with 0 and 100 ng/mL aureobasidin A. E EMSA analysis demonstrates the specific binding of WRKY1 to the W-box element of the EPS1 promoter. Competitor refers to the unlabeled biotin probe. The mutated W-box element sequence corresponds to that in Figure D. F and G LUC analysis indicates that WRKY1 positively regulates the activity of the EPS1 promoter-driven LUC. The mutated W-box element sequence corresponds to that in Figure D. H Endogenous SA content in EPS1-overexpressing lines. OE-EPS1 represents EPS1-overexpressing plants, and EV represents empty vector control plants. The data represent the means and standard deviations of three independent replicate experiments. Asterisks (*) indicate significant differences from the control (Student’s t test, **P < 0.01)