Fig. 4. Complementation of Arabidopsis B-class mutants ap3 and pi by their maize orthologs. (A-E) Arabidopsis flowers of (A) wild type, (B) ap3-3 mutant, (C) ap3-3 with AP3pro:Si1 transgene, (D) pi-1 mutant with AP3pro:Zmm16 transgene (note white sepal margins), and (E) ap3-3 pi-1 double mutant with both AP3pro:Si1 and AP3pro:Zmm16 transgenes (note white petals and sepals). (F-J) Scanning electron microscopy (SEM) of flowers from the same plants from which the flowers shown in A-E were obtained, in the same order. (K-O) SEM of abaxial petal or second whorl organ epidermis from flowers shown in F-J, in the same order. Cells of wild-type petal epidermis (K) are rounded and no guard cells are present. Cells of second whorl `sepal' epidermis of ap3-3 mutant (L) are elongated and irregular, with many guard cells. Rescued mutants (M-O) have epidermal cells that are intermediate in shape between those seen in K and L, with occasional guard cells. Note the lack of elongated epidermal cells characteristic of sepals. Arrows in L, N and O indicate guard cells. Scale bars: 0.5 mm in F-J; 50 µm in K-O.