Background: The genus Aquilegia is an emerging model system in plant evolutionary biology predominantly because of its
wide variation in floral traits and associated floral ecology. The anatomy of the Aquilegia flower is also very distinct. There
are two whorls of petaloid organs, the outer whorl of sepals and the second whorl of petals that form nectar spurs, as well
as a recently evolved fifth whorl of staminodia inserted between stamens and carpels.
Methodology/Principal Findings: We designed an oligonucleotide microarray based on EST sequences from a mixed tissue,
normalized cDNA library of an A. formosa x A. pubescens F2 population representing 17,246 unigenes. We then used this array
to analyze floral gene expression in late pre-anthesis stage floral organs from a natural A. formosa population. In particular, we
tested for gene expression patterns specific to each floral whorl and to combinations of whorls that correspond to traditional
and modified ABC model groupings. Similar analyses were performed on gene expression data of Arabidopsis thaliana whorls
previously obtained using the Ath1 gene chips (data available through The Arabidopsis Information Resource).
Conclusions/Significance: Our comparative gene expression analyses suggest that 1) petaloid sepals and petals of A.
formosa share gene expression patterns more than either have organ-specific patterns, 2) petals of A. formosa and A.
thaliana may be independently derived, 3) staminodia express B and C genes similar to stamens but the staminodium
genetic program has also converged on aspects of the carpel program and 4) staminodia have unique up-regulation of
regulatory genes and genes that have been implicated with defense against microbial infection and herbivory. Our study
also highlights the value of comparative gene expression profiling and the Aquilegia microarray in particular for the study of
floral evolution and ecology.
Voelckel, C., Borevitz, J. O., Kramer, E. M., & Hodges, S. A. (2010). Within and between Whorls: Comparative Transcriptional Profiling of Aquilegia and Arabidopsis. Plos One, 5(3), e9735. doi: 10.1371/journal.pone.0009735
2010 Voelckel et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This work was funded under a National Science Foundation grant to SA Hodges (http://www.nsf.gov/awardsearch/showAward.do?AwardNumber
= 0412727). C Voelckel acknowledges funding from the Alexander von Humboldt Foundation through a Feodor Lynen Fellowship. The funders had no role in
study design, data collection and analysis, decision to publish, or preparation of the manuscript.