Expression of the HAE::GUS abscission zone marker is displaced in as1 medial sepals. Images of wild-type and mutant flowers (stage 17) histochemically stained for β-Glucuronidase (GUS) activity. Medial (A-D) and lateral (E-H) views are shown. A/E: In wild-type flowers, HAE regulatory regions direct expression of GUS in discrete domains of the remaining sepal (se), petal (pe) and stamen (st) abscission zone cells. B/F: In as1-20 flowers, GUS is expressed in an inverted V-shaped proximal region of the medial sepals (B), and in the remaining petal and lateral sepal stubs (B/F). C/D/G/H: Expression of GUS expands beyond the enlarged sepal abscission zones of as1-20 bp-1 (C/G) and bp-1 (D/H) flowers into the distal pedicels. Scale bars: 200 μm.