In the absence of SA induction, non-transformed onion epidermal cells did not show
GUS staining (Figure 5a) whereas onion epidermal cells transformed with the CaMV35S
promoter (positive control) did show staining (Figure 5b). Onion epidermal cells transformed by
pCAMBIA1301-Ah-Chi-P showed light staining without SA induction (Fig. 5c), but displayed deeper
staining after SA induction (Fig. 5d). Thus, Ah-Chi-P is a promoter that can be induced by SA.
Onion epidermal cells transformed with the 5'-deleted promoters P1 to P5 were also stained after
SA induction (Figure 5e-i). The intensity of staining varied depending on the sequences deleted,
indicating differences in the levels of activity driven by promoters P1 to P5
.