Fig. 1. Phenotypes of wild type, cuc1 cuc2, pin1 and pin1 cuc1 cuc2. (A-H) 4-day-old seedlings of wild type (A,B), cuc1 cuc2 (C,D), pin1-3 (E,F) and pin1-3 cuc1 cuc2 (G,H). In B,D and H, seedlings were cleared to visualize the vascular pattern. A wild-type seedling has two symmetrically arranged, completely separated cotyledons (A) and each cotyledon contains a single mid-vein (B, arrows). cuc1 cuc2 has two bilaterally symmetrical cotyledons, as revealed by two splits at the top (arrowheads in C,D) and a vascular pattern similar to wild type (D). Arrow in D indicates one of the two mid veins (the other one is out of focus). pin1 shows variable phenotypes including two completely separated cotyledons (E), partial fusion and increased number of cotyledons (F, left and center) and a wide collar-shaped cotyledon (F, right). The fused part is indicated by arrowheads. pin1 cuc1 cuc2 shows a radially symmetrical morphology as revealed by complete cotyledon fusion (G) and evenly distributed vascular bundles (H). (I-L) Scanning electron micrograph images of wild-type (I), cuc1 cuc2 (J), pin1-3 (K) and pin1-3 cuc1 cuc2 (L) embryos. Note that two splits are apparent at the top of a cup-shaped cotyledon in cuc1 cuc2 (J, arrowheads) while no such split is found in pin1 cuc1 cuc2 (L).