A GENETIC FRAMEWORK FOR FLORAL PATTERNING

The initial steps of newer development involve two classes of consecut ively acting regulatory genes. Meristem-identity genes, which act earl y to control the initiation of flowers, are expressed throughout the i ncipient floral primordium. Homeotic genes, which act later to specify the identify of individual floral organs, are expressed in distinct d omains within the flower. The link between the two classes of genes ha s remained unknown so far. Here we show that the meristem-identity gen e LEAN has a role in controlling homeotic genes that is separable from its role in specifying floral fate. On the basis of our observation t hat LEAFY activates different homeotic genes through distinct mechanis ms, we propose a genetic framework for the control of floral patternin g.