Phylogenetic Analysis of the "ECE" (CYC/TB1) Clade Reveals Duplications Predating the Core Eudicots

Flower symmetry is of special interest in understanding angiosperm evolution and ecology. Evidence from the Antirrhineae (snapdragon and relatives) indicates that several TCP gene-family transcription factors, especially CYCLOIDEA (CYC) and DICHOTOMA (DICH), play a role in specifying dorsal identity...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2006-06, Vol.103 (24), p.9101-9106
Main Authors: Howarth, Dianella G., Donoghue, Michael J.
Format: Article
Language:English
Subjects:
Angiosperms
Antirrhinum - anatomy & histology
Antirrhinum - classification
Antirrhinum - genetics
Asterales
Bayes Theorem
Biological Sciences
Botany
Caprifoliaceae
Cycloidea
DNA-Binding Proteins
Ecology
Evolution
Evolution, Molecular
Flower buds
Flowers
Flowers & plants
Flowers - genetics
Flowers - physiology
Gene Duplication
Gene expression
Genes
Lonicera morrowii
Molecular Sequence Data
Petals
Phylogenetics
Phylogeny
Plant ecology
Plant Proteins - genetics
Plants
Taxa
Transcription Factors - genetics
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Summary:Flower symmetry is of special interest in understanding angiosperm evolution and ecology. Evidence from the Antirrhineae (snapdragon and relatives) indicates that several TCP gene-family transcription factors, especially CYCLOIDEA (CYC) and DICHOTOMA (DICH), play a role in specifying dorsal identity in the corolla and androecium of monosymmetric (bilateral) flowers. Studies of rosid and asterid angiosperms suggest that orthologous TCP genes may be important in dorsal identity, but there has been no broad phylogenetic context to determine copy number or orthology. Here, we compare published data from rosids and asterids with newly collected data from ranunculids, caryophyllids, Saxifragales, and Asterales to ascertain the phylogenetic placement of major duplications in the "ECE" (CYC/TB1) clade of TCP transcription factors. Bayesian analyses indicate that there are three major copies of "CYC" in the ECE clade, and that duplications leading to these copies predate the core eudicots. CYC1 contains no subsequent duplications and may not be expressed in floral tissue. CYC3 exhibits similar patterns of duplication to CYC2 in several groups. Using RT-PCR, we show that, in flowers of Lonicera morrowii (Caprifoliaceae), DipsCYC2B is expressed in the four dorsal petals and not in the ventral petal. DipsCYC3B is expressed in flower and petal primordia, possibly most strongly in the ventral petal.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0602827103