NaHS increases the activity of α-amylase in incubation medium of barley aleurone layers in the absence (a) and presence ((b), (c)) of GA. Barley aleurone layers isolated from treated embryoless half grains are incubated in 0, 0.005, 0.05, 0.25, or 0.5 mM NaHS for 24 h ((a), (b)). After incubation, aleurone layers are placed on agar-starch medium (containing 4% agar and 0.1% starch) for 16 h. Agar plates are stained with I2-KI solution to detect the activity of α-amylase (a). (b) shows native PAGE analysis of α-amylase activity in incubation medium surrounding the aleurone layers. (c) indicates secreted α-amylase activity in incubation medium surrounding barley aleurone layers treated with water (control), GA, or GA + NaHS (GA + H2S) at different times of incubation. Data in (c) are expressed as means ± SD of three independent experiments with three replicates of 20 embryoless half grains per treatment.