P. sojae was cultured on PDA media for 10–14 days. Three agar plugs (0.6 cm diameter) were cut from the actively growing edges of the plates and inoculated into 5 mL PDB. The inoculated PDB were then incubated by shaking at 150 rpm and 25 °C for 3 days. One-fifth volume (1 mL) of PDB culture was subsequently removed from the liquid culture and replaced with 1 mL (10 μg/μL) of the EtOAc extract of KACC 40557. The same volume of acetone–water (1:9, v/v) was added to the liquid culture instead of the extract as a control. The cultures were incubated with shaking at 150 rpm and 25 °C for 0.5, 1, 6 and 12 h, after which the mycelia were harvested and RNA was extracted using an RNeasy plant mini kit (Qiagen, Valencia, CA, USA).