Figure 2. gusA expression patterns observed between transformed IEs treated with 2,4-D and those not treated with 2,4-D prior to bombardment.

(A) Randomly selected IEs assayed for gusA activity.
(B) In the presence of the gusA gene, substrate produced blue deposits as indicated by blue stains observed in successfully transformed cells and tissues. On the other hand, the absence of blue stain indicates the absence of gusA gene, which failed to produce blue deposit.
(C) Shades of blue stains (indicating gusA expression) were detected on transformed IEs spreading over the entire IEs treated with 2,4-D prior to bombardment. Prominent longitudinal blue stains probably along vascular bundles were also detected in 2,4-D treated IEs. No blue spot or stains were detected on all non-transformed sample (control).
(D) Only localized blue spots (distinct and isolated) were observed on IEs not treated with 2,4-D prior to bombardment. (E)Plantlets regenerated showed no difference in growth between those from double bombarded IEs (left) and from single bombardment (right).