Figure 1.

The phas promoter drives expression in seed embryo but not in leaf tissue. (A) Transcriptional activity detected by run-on analysis using nuclei from mid-maturation embryos or leaves from a tobacco plant containing a single copy of −1470phas/uidA. Labeled run-on RNA was hybridized to a slot blot containing plasmid DNA encoding GUS or 18S ribosomal RNA. (B) Histochemical staining of a representative seed embryo and a leaf from the plant used in A. Blue color reveals accumulated GUS protein.