A homolog of NO APICAL MERISTEM is an immediate target of the floral homeotic genes APETALA3/PISTILLATA

To understand how homeotic genes affect morphogenesis and differentiation, their target genes must be identified. In Arabidopsis flowers, the homeotic protein heterodimer APETALA3/PISTILLATA is necessary for petal and stamen formation. Here, AP3/PI function was put under posttranslational control to analyze its immediate effect on the floral mRNA population, with indirect effects blocked by cycloheximide. Using differential display, a target gene of AP3/PI was identified (NAP: NAC-LIKE, ACTIVATED BY AP3/PI), which is homologous to genes required for meristem establishment and separation of floral organs. The expression pattern of NAP and the phenotypes caused by its mis-expression suggest that it functions in the transition between growth by cell division and cell expansion in stamens and petals.