Plant materials

Seedlings of maize (Zea mays L. inbred line Huayu 5, provided by Hubei Provincial Seed Group Co.,LTD) were sterilized and germinated, and then grown with water culture method for 72h at 25°C, no light condition and 70% relative humidity [29]. The 100 nM OA (S1786, Beyotime) was applied to stimulate the root of maize seedlings, based on the working concentration in maize reported by Sheen (1993) [25]. To initiate planned treatment, 3d-old seedlings were distributed into two groups, which were treated with distilled water and 100 nM OA respectively. After 24 h, 48 h and 72 h, leaves from different conditions were collected and processed for different assays.