Flower development in the asterid lineage.

A complete understanding of the genetic control of flower development requires a comparative approach, involving species from across the angiosperm lineage. Using the accessible model plant Arabidopsis thaliana many of the genetic pathways that control development of the reproductive growth phase have been delineated. Research in other species has added to this knowledge base, revealing that, despite the myriad of floral forms found in nature, the genetic blueprint of flower development is largely conserved. However, these same studies have also highlighted differences in the way flowering is controlled in evolutionarily diverse species. Here, we review flower development in the eudicot asterid lineage, a group of plants that diverged from the rosid family, which includes Arabidopsis, 120 million years ago. Work on model species such as Antirrhinum majus, Petunia hybrida, and Gerbera hybrida has prompted a reexamination of textbook models of flower development; revealed novel mechanisms controlling floral gene expression; provided a means to trace evolution of key regulatory genes; and stimulated discussion about genetic redundancy and the fate of duplicated genes.