Beyond the ABCs: ternary complex formation in the control of floral organ identity

The production of a flower requires several events to occur. A floral meris tem must form, boundaries must be set to enable discrete primordia to arise and the primordia must adopt the correct organ identity. Homeotic mutants, whose organs adopt inappropriate identities for their position within the flower, have helped the construction of a simple combinatorial model to exp lain how floral organ identity is defined. However, recent experiments sugg est that the regulation of floral organ identity is more complex than was p reviously apparent. The simple interactions are becoming more complex and t he universal applicability of the model less clear.