American Journal of Botany 92(8): 1284–1293. 2005. DUPLICATION OF FLORAL REGULATORY GENES IN THE LAMIALES1

Duplication of some floral regulatory genes has occurred repeatedly in angiosperms, whereas others are thought to be single-copy in most lineages. We selected three genes that interact in a pathway regulating floral development conserved among higher tricolpates (LFY/FLO, UFO/FIM, and AP3/DEF) and screened for copy number among families of Lamiales that are closely related to the model species Antirrhinum majus. We show that two of three genes have duplicated at least twice in the Lamiales. Phylogenetic analyses of paralogs suggest that an ancient whole genome duplication shared among many families of Lamiales occurred after the ancestor of these families diverged from the lineage leading to Veronicaceae (including the single-copy species A. majus). Duplication is consistent with previous patterns among angiosperm lineages for AP3/DEF, but this is the first report of functional duplicate copies of LFY/FLO outside of tetraploid species. We propose Lamiales taxa will be good models for understanding mechanisms of duplicate gene pres-ervation and how floral regulatory genes may contribute to morphological diversity. Key words: floral regulatory genes; gene duplication; Lamiales. Morphological innovations are thought to frequently involve divergence among duplicated genes that comprise key genetic pathways regulating development (Raff, 1996; Carroll et al., 2001). Though most evidence comes from comparisons among animals, a similar pattern is beginning to emerge for flowerin