HUA1 and HUA2 are two members of the floral homeotic AGAMOUS pathway

The identities of the four floral organ types in an Arabidopsis flower are specified by the combinatorial activities of the floral homeotic A, B, and C function genes; AGAMOUS is the only known C function gene. We have identi fied two genes that interact with AG in the specification of floral structu re, HUA1 and HUA2, from a screen for enhancers of a weak ag allele, ag-4. H UA1 and HUA2 are involved in all aspects of AG function. HUA2 encodes a nov el protein that contains nuclear localization signals and signature motifs that suggest HUA2, like AG, may be a transcription factor. Molecular analys es suggest that HUA2 land possibly HUA1) acts to facilitate AG action at th e same hierarchical level as AG.