(Aand B) Confocal projections of the IM (A) (same as Figure 1A) and the VM of a seedling 5DAS (B) showing expression pattern of REV-2 ×YPet (red), KAN1−2 × GFP (green) and PIN1-CFP (blue). Primordium (P) and incipient primordium (i) stages are numbered from i3-P2 in (A) based on convention described in (Heisler et al., 2005). Leaves in (B) are numbered starting from oldest to youngest. (C–L) Magnified views of i3 (C), i2 (E), i1 (G), P1(I) and P2 (K) marked in (A); Longitudinal optical sections of i3 (D), i2 (F), i1 (H), P1(J) and P2 (L) along the dashed lines marked in (A) showing gradual changes in REV and KAN1 expression during different stages of floral bract development. Note the presence of a gap between REV and KAN1 expression in the youngest incipient primordium i3 (white arrowheads in (C) and (D)) and extension of REV at a later stage into the developing primordium i2 (E and F). At the next stage i1, REV expression starts to decrease in the surrounding cells (white arrowheads in (G) and (H)). At P1 stage, in the regions where PIN1 polarities have reversed away completely from the primordium, REV expression reduces further (I and J) and KAN1 expression starts to re-appear (white arrowheads in I). At the next stage P2, KAN1 expression is re-established in the vicinity of the primordium (white arrowhead in (K)), REV expression is restricted to the center of the primordium and a gap between REV and KAN1 expression re-appears (white arrowheads in L). (M–R) Magnified views of leaf 5 (M), leaf 4 (O), and leaf 3 (Q) marked in (B); Longitudinal optical sections of leaf 5 (N), leaf 4 (P), and leaf 3 (R) along the dashed lines marked in (B) showing gradual changes in REV and KAN1 expression during different stages of leaf primordium development. Again, note the presence of a gap between REV and KAN expression in the youngest leaf primordium 5 (white arrowheads in (M) and (N)) and extension of REV at a later stage into the developing primordium 4 (O and P), while KAN 1 expression appears relatively static (O and P). At a later stage, REV expression decreases adaxial to the primordium (Q and R) as KAN1 expression starts to appear (white arrowheads in Q) and a gap between REV and KAN1 expression is re-established (white arrowheads in R). Scale bars 20 μm (A), 15 μm (B) and 5 μm (C–R).