title: Conservation and canalization of gene expression during angiosperm diversification accompany the origin and evolution of the flower.
abstract: The origin and rapid diversification of the angiosperms (Darwin's "Abominable Mystery") has engaged generations of researchers. Here, we examine the floral genetic programs of phylogenetically pivotal angiosperms (water lily, avocado, California poppy, and Arabidopsis) and a nonflowering seed plant (a cycad) to obtain insight into the origin and subsequent evolution of the flower. Transcriptional cascades with broadly overlapping spatial domains, resembling the hypothesized ancestral gymnosperm program, are deployed across morphologically intergrading organs in water lily and avocado flowers. In contrast, spatially discrete transcriptional programs in distinct floral organs characterize the more recently derived angiosperm lineages represented by California poppy and Arabidopsis. Deep evolutionary conservation in the genetic programs of putatively homologous floral organs traces to those operating in gymnosperm reproductive cones. Female gymnosperm cones and angiosperm carpels share conserved genetic features, which may be associated with the ovule developmental program common to both organs. However, male gymnosperm cones share genetic features with both perianth (sterile attractive and protective) organs and stamens, supporting the evolutionary origin of the floral perianth from the male genetic program of seed plants.
authors.affiliation: Department of Biology and Florida Museum of Natural History, University of Florida, Gainesville, FL 32611, USA. achander@ufl.edu
authors.forename: André S
authors.initials: AS
authors.lastname: Chanderbali
authors.forename: Mi-Jeong
authors.initials: MJ
authors.lastname: Yoo
authors.forename: Laura M
authors.initials: LM
authors.lastname: Zahn
authors.forename: Samuel F
authors.initials: SF
authors.lastname: Brockington
authors.forename: P Kerr
authors.initials: PK
authors.lastname: Wall
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Gitzendanner
authors.forename: Victor A
authors.initials: VA
authors.lastname: Albert
authors.forename: James
authors.initials: J
authors.lastname: Leebens-Mack
authors.forename: Naomi S
authors.initials: NS
authors.lastname: Altman
authors.forename: Hong
authors.initials: H
authors.lastname: Ma
authors.forename: Claude W
authors.initials: CW
authors.lastname: dePamphilis
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Soltis
authors.forename: Pamela S
authors.initials: PS
authors.lastname: Soltis
mesh_terms: D017360:Arabidopsis / Q000235:genetics; D016000:Cluster Analysis; D029784:Cycas / Q000235:genetics; D019143:Evolution, Molecular; D035264:Flowers / Q000235:genetics*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D014644:Genetic Variation; D019684:Magnoliopsida / Q000145:classification / Q000235:genetics*; D031654:Nuphar / Q000235:genetics; D027421:Persea / Q000235:genetics; D010802:Phylogeny; D013045:Species Specificity; D032481:Zamiaceae / Q000235:genetics