The Arabidopsis AGL8 MADS box gene is expressed in inflorescence meristems and is negatively regulated by APETALA1.

MADS box genes encode putative transcription factors that play important roles in plant and animal development. In plants, MADS box genes are involved in the early step of specifying floral meristem identity as well as the later step of determining the fate of floral organ primordia. Here, we describe the isolation and characterization of a new MADS box gene from Arabidopsis, designated AGL8. Although AGL8 RNA does not accumulate during vegetative growth, it accumulates to high levels in the inflorescence apical meristem as well as in the inflorescence stem and cauline leaves. AGL8 RNA is excluded from the young flower primordia that arise on the flanks of the inflorescence meristem but later accumulates in the walls of the developing carpels. The lack of AGL8 RNA in floral meristems is due in part to the action of another MADS box gene, APETALA1, because AGL8 RNA does accumulate in apetala1 mutant flower primordia.