Fig. 3. AS1 represses the expression of BP in the Arabidopsis gynoecium. (A) In situ localization of AS1 mRNA in a cross section of a Col pistil (stage 10), showing strong expression in valves and lower levels in replum. (B) A control section of a Col pistil (stage 10) hybridized with a sense probe, showing no signal. (C-G) Staining from the KNAT1::GUS-18 reporter in Col and as1-1. In the wild-type background, staining is restricted to the replum, valve margin and style of stage 12 gynoecia (C,E), and the same staining is seen in a fruit at stage 15 (G). In the as1-1 background, valves of stage 12 gynoecia show ectopic expression of BP (D,F). (H,I) Staining from the KNAT1::GUS-1 reporter allows the detection of variations in expression intensity, and shows that BP expression in the replum of stage 15 fruits is more intense in the as1-1 mutant (I) than in the wild-type (H) background. All gynoecia and fruits are in the ER background. Scale bars: 1 mm in G; 0.5 mm in H,I; 200 µm in C,D; 100 µm in A,B,E,F. r, replum; st, style; v, valve.