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from violet cress. Their exon sequences show ;90% nucleotide similarity with Arabidopsis LFYand 99% similarity to each other. We used in situ hybridization to study vcLFY expression in violet cress. The patterns were very similar to LFY in Arabidopsis except for stronger expression in the shoot apical meristem outside of the region of flower meristem initiation. It is possible that the relatively diffuse expression of vcLFY contributes to the lack of bract suppression in violet cress. Additionally, the earliest flowers produced by violet cress express vcLFY, suggesting that accelerated flowering in violet cress could also result from changes in the regulation of vcLFY. The placement of flowers on a plant has profound ecological significance. It is, therefore, desirable that we understand how flower disposition is regulated in a given species and how it becomes modified in the course of evolution. The approach taken in this paper is to compare a well-studied model system, Arabidopsis [Arabidopsis thaliana (L.)Heynh.], with another member of Brassicaceae, violet cress [Jonopsidium acaule (Desf.)Rchb.]. Whereas Arabidopsisflowers are borne on elongated, leafless, inflorescences, violet cress flowers emerge from the axils of rosette leaves (Figs. 1‐2). Here we explore the possible role of a floral meristem identity gene, LEAFY (LFY), in the evolution of rosette flowering. The vegetative phase of development in Arabidopsis, violet cress, and almost all other Brassicaceae involves the formation of a rosette: a series of spirally arranged leaves with relatively short internodes. The meristems in the axils of these rosette leaves have the potential to pro |
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