title: Diversification of CYCLOIDEA expression in the evolution of bilateral flower symmetry in Caprifoliaceae and Lonicera (Dipsacales).
abstract: OBJECTIVE
  The expression of floral symmetry genes is examined in the CYCLOIDEA lineage following duplication, and these are linked to changes in flower morphology. The study focuses on Dipsacales, comparing DipsCYC2 gene expression in Viburnum (radially symmetrical Adoxaceae) to members of early-diverging lineages of the bilaterally symmetrical Caprifoliaceae (Diervilla and Lonicera).
  
  
  METHODS
  Floral tissue from six species, which included dorsal, lateral and ventral regions of the corolla, was dissected. RNA was extracted from these tissues and each copy of DipsCYC2 was amplified with reverse transcriptase PCR.
  
  
  RESULTS
  Members of DipsCYC2 were expressed across the corolla in the radially symmetrical Viburnum plicatum. A shift to bilaterally symmetrical flowers at the base of the Caprifoliaceae was accompanied by a duplication of the DipsCYC2 gene, resulting in DipsCYC2A and DipsCYC2B, and by loss of expression of both of these copies in the ventral petal. In Lonicera (Caprifolieae), there is a shift from flowers with two dorsally and three ventrally oriented corolla lobes to a clear differentiation of dorsal, lateral and ventral lobes. This shift entailed a decoupling of expression of DipsCYC2A and DipsCYC2B; DipsCYC2B continues to be expressed in the dorsal and lateral lobes, while DipsCYC2A expression is restricted to just the two dorsal lobes. A reversion to more radially symmetrical flowers within Lonicera was accompanied by a re-expansion of expression of both DipsCYC2A and DipsCYC2B.
  
  
  CONCLUSIONS
  The transition to bilateral symmetry in Caprifoliaceae involved: (a) duplication of an ancestral DipsCYC2 gene; (b) the loss of expression of both of these copies in the ventral petal; and (c) changes in the zone of expression, with one copy continuing to be expressed across the dorsal and lateral petals, and the other copy becoming restricted in expression to the dorsal corolla lobes.
authors.affiliation: Department of Biological Sciences, St John's University, Jamaica, NY 11439, USA. howarthd@stjohns.edu
authors.forename: Dianella G
authors.initials: DG
authors.lastname: Howarth
authors.forename: Tiago
authors.initials: T
authors.lastname: Martins
authors.forename: Edward
authors.initials: E
authors.lastname: Chimney
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Donoghue
mesh_terms: D031003:Adoxaceae / Q000033:anatomy & histology / Q000235:genetics*; D001483:Base Sequence; D005075:Biological Evolution; D027922:Caprifoliaceae / Q000033:anatomy & histology / Q000235:genetics*; D035264:Flowers / Q000033:anatomy & histology / Q000235:genetics*; D020440:Gene Duplication; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D018749:RNA, Plant / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D018749:RNA, Plant