Biochemical assay kits

The seedlings of control and transgenic maize were germinated in Petri dishes for 3 days under dark conditions. After germination, control and transgenic maize seeds were transplanted in seedling trays filled with fertile soil and placed in a greenhouse (16 h light/8 h dark photoperiod, 25 °C). When the seedlings grew to the three-leaf stage, they were treated with drought stress by withholding watering. The plants received water after approximately 14 days, and the survival rate of the plants was determined 3 days later. Leaves of the 14-day-old maize were collected. The leaves were weighed after 0, 0.5, 1, 1.5, 2, and 4 h at room temperature, respectively. The leaves were then dried in an oven at 65 °C for 24 h; their dry weights were recorded and the water-loss rates were calculated as water loss (%) = (initial fresh weight − final fresh weight)/initial fresh weight × 100. Chlorophyll content was determined using the SPAD-502 Chlorophyll Meter. The MDA content, CAT activity, and SOD activity were determined using biochemical assay kits (Solarbio, Beijing, China). Anthocyanin content was measured using the method established by Drumm-Herrel and Mohr (1982) [55 (link)]. All samples had three biological replicates. Normally watered plants were used as the control in all experiments.