Overexpression of MdWRKY75 enhances apple resistance to Fusarium solani. A) Phenotype of plants overexpressing MdWRKY75 in the roots under F. solani treatment. Scale bar = 10 cm. B) Observation of MdWRKY75-overexpressing roots under F. solani treatment. The black arrow indicates the wound. Scale bar = 100 μm. C) Height of plants overexpressing MdWRKY75 in the roots under F. solani treatment. D) Vitality of MdWRKY75-overexpressing roots under F. solani treatment. E) REL of MdWRKY75-overexpressing roots under F. solani treatment. WT-pBIN, GL3 transformed with an empty vector containing the GFP tag; WRKY75 OE 1–6, different MdWRKY75-overexpressing root lines. Data are shown as means ± standard deviation (Sd) with three biological replicates. Different letters indicate significant differences between treatments based on Student's t-test (*P ≤ 0.05; **P ≤ 0.01).