Reporter gene assays in stably transformed Arabidopsis plants. A: Histochemical localization of GUS expression in transgenic Arabidopsis plant carrying 3xFORCA-pCAMBIA. a, 4 day-old seedling; b, 10 day-old plant; c, 30 day-old plant showing GUS staining in pollen grains and sepals; d, Silique showing GUS activity at the top of developing peduncle; e, control 4 day-old seedling carrying the 35Smin-pCAMBIA;f-k, 7 day-old seedlings treated with 0.05% EtOH (f, h and j) or a 24 h SA (1 mM) treatment (g, i and k) under different light conditions: continuous light (f-g), normal light (h-i), or continuous dark (j-k). B: Fluorometric analysis of GUS specific activities in protein extracts of 3xFORCA-pCAMBIA plants. Ten day-old plants were treated by either continuous light (CL), normal light (NL) or continuous dark (CD) for three days. After two days light treatment, plants were sprayed with 0.05% EtOH (grey bars) or 1 mM SA (white bars) and shock frozen for protein extraction. Mean and standard error were calculated from six pooled data points generated in three independent experiments, each with two transgenic lines. Based on T-tests all differences between mock and SA-treated samples were significant (p = 9.82E-06 for CL; p = 0.038 for NL and p = 0.0053 for CD). Differences between mock-treated CL and NL samples were also significant (p = 0.0014).