Results and Discussion
Transient GUS gene expression analysis. Initially two promoters,
the 35S RNA promoter from cauliflower mosaic virus (CaMV)
and the actin 1 (Act1) promoter from rice, fused to gusA were
analyzed. The 35S and Act1 promoters have been previously demonstrated
to direct high levels of gene expression in transformed dicots
and monocots, respectively (McElroy et al., 1990; Zhang et al.,
1991). We expected that GUS expression in Gladiolus would be
highest from the Act1 promoter since this promoter is most active
in monocots while the CaMV 35S promoter is relatively inactive
in monocots. Surprisingly, transient GUS expression levels in
bombarded Gladiolus cells were nearly 5-fold higher from the
CaMV 35S, promoter than from the Act1 promoter