Figure 7. Model depicting UFO activation of LFY and their roles in the early stages of lateral meristem development.

A. UFO (blue) is expressed in the peripheral zone of the shoot apical (SAM) and inflorescence (IM) meristems. UFO is later induced in the centre of stage 2 floral meristems and its expression domain is restricted to the second and third whorls during later stages [17], [34]. LFY expression (shades of orange) is initiated in the P0 leaf primordium and progressively increases in the later stages; its expression becoming prominent when floral meristems are initiated. The UFO and LFY expression domains overlap in the lateral P0 and P1 leaf primordia in the SAM, in stage 0 floral primordia in the IM, and in the petal, stamen and carpel whorls upon establishment [8], [36]. B. LFY activity is enhanced by UFO in the emerging lateral meristems/primordia within the peripheral zones of the meristems to ensure their establishment and fating. Lower LFY activity without UFO promotes the organogenesis of the primordia during later stages.