Effect of several stresses on GUS expression in Prom280:GUS and Prom290:GUS lines. Ten-day-old Arabidopsis seedlings were grown on MS agar at 21°C and incubated for 6 h to high light (800 μmol m-2 s-1). For other stress conditions, Arabidopsis plants were cultivated on MS agar supplemented with 50 mM NaCl, 0.1 μM MV, 100 mM mannitol or 1.3 mg/mL elicitors. GUS activity was quantified in whole aerial part using MU as substrate. Each point on the bar represents a single replicate (blue bars for Prom280:GUS line and red bars for Prom290:GUS line). Asterisks (**) indicate significant differences between treatments and controls according to Student's t-Test at P < 0.05. Note the scale difference between Prom280:GUS and Prom290:GUS lines.