Developmental and Structural Section
Howarth, Dianella G. , Donoghue, Michael J. .
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 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” clade (CYC/TB1) 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.
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1 - Yale University, Department Ecology & Evolutionary Biology, Po Box 208105, New Haven, Connecticut, 06520-8105, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 312/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 10:45 AM