Confocal microscopic analysis of AP1:GFP localisation in inflorescence meristem and early flower bud stages. (A) Overview of an inflorescence with the inflorescence meristem and early flower bud stages 1 to 6 indicated. AP1:GFP protein is detected as green signal in a red autofluorescent background. (B) Detail of the inflorescence meristem in (A) showing that the AP1:GFP signal starts in a few cells in stage 1 flower buds and spreads to all cell layers in flower bud stage 2 and 3. The asterisk denotes AP1:GFP signal in nuclei of the adjacent stage 2 flower bud projecting through the overlying inflorescence meristem tissue. (C) Detail of a late stage 3 flower bud showing AP1:GFP signal in all cell layers of the four sepals and the floral meristem. (D) Detail of a stage 4 flower bud showing the highest AP1:GFP signal in the tips of the four sepals and lower signal at positions where the petals will emerge. The signal in whorl 3 and whorl 4 is reducing, although the signal does remain in whorl 4. (1–6) flower bud stages; (FM) floral meristem; (IM) inflorescence meristem; (p) petal; (s) sepal; (w4) whorl 4. Scale bar of (A) 50 μm and scale bars of (B-D) 25 μm.