GUS enzymatic activity in back-transformed lines of the dessert banana 'Grande Naine' carrying uidA gene fusion to the full-length promoter sequence 17-1 or the positive control maize ubiquitin promoter. Each entry is the average ± standard error (± SE) result of three independent measurements after correction for the background obtained by untransformed controls. Cultures transformed with the empty control vector pCAMBIA-1391Z were not distinguishable from untransformed controls. (A) GUS enzymatic activity assay of LT treated (8°C for 10 h) transgenic (undifferentiated) cell colonies (stage I) 6 months after back-transformation. For each entry, at least 30 independent cell colonies (170 mg fresh weight in total) were pooled. The SE for the activity of promoter sequence 17-1 at 26°C was zero. (B) GUS enzymatic activity assay of LT treated (8°C for 18 h) transgenic in vitro plants (stage III), 19 months after transformation. For each independent line proteins were extracted from at least 250 mg leaf (L) and 200 mg root (R) tissue. The SE for the activity of promoter sequence 17-1 in root tissue of line no. 2 is not visible (only ± 5 and ± 3, at 26°C and 8°C, respectively).