Fig. 4.

Interaction between PsCYCs and SYP1, floral diagrams, and the establishment of floral zygomorphy. (a–f) syp1 mutants and syp1-1 in different genetic backgrounds. Front and side views of flowers and flattened petals from wild type and mutants are shown. (a) Wild-type pea flower. (b) syp1-1 flower bears symmetrical lateral and ventral petals (white arrow). The ventral petals possess a keel structure. Yellow arrow: the additional ventral petal, which is cut along the edge of the keel. (c) syp1-2 flower with symmetrical lateral petals (white arrow). (d) lst1-1 syp1-1 flower displays an additive phenotype. (e) k-1 syp1-1 flower has abnormal dorsal petals (white arrow). (f) k-1 lst1-1 syp1-1 flower has radial symmetry with five ventralized symmetrical petals. In d–f, all ventralized petals were cut to make them flat. (Scale bar, 10 mm.) (g) Floral diagrams of wild type and various default states in Antirrhinum and pea. In wild type, both flowers have three distinct petals and possess DV (red lines with arrow) and IN asymmetry (broken lines). In the ventralized (−DV) default forms, all petals of pea flower manifest IN asymmetry, whereas those of Antirrhinum are symmetric. In syp1, the (−IN) default form still possesses DV asymmetry. In k lst1 syp1, the (−DV−IN) default form displays radial symmetry. Based on work on Lotus, another radial symmetry form is expected when PsCYCs are ectopically expressed, and all petals mimic the dorsal. Furthermore, flowers with left-right asymmetry could be found as the variation of (−DV) default form. (h) Functions and interactions of DV and IN regulators in pea. DV and IN asymmetries are separately controlled by PsCYCs and SYP1. PsCYCs can suppress the manifestation of IN asymmetry and couple IN with DV asymmetry. SYP1 can interact with PsCYCs to regulate organ primordium initiation, presumably modifying DV orientation. The interaction of SYP1 and PsCYCs is important for zygomorphic development in legumes.