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Abstract:
In flowering plants, the homeotic gene AGAMOUS (AG) and its orthologs control the development of the reproductive floral organs, stamens and carpels. In the reference plant Arabidopsis thaliana, sequences necessary and sufficient for AG expression in the center of flowers are located in the second intron, which is about 3 kb in size. This intron contains binding sites for two transcription factors, LEAFY (LFY) and WUSCHEL (WUS), which are direct activators of AG, as well as several other putative regulatory elements. We have used phylogenetic footprinting along with functional tests to examine the conservation and divergence of cis-regulatory elements in the AG intron. Although there is little obvious sequence conservation outside the Brassicaceae, except for an AAGAAT box and a pair of CCAATCA boxes, the intron from cucumber AG has at least partial activity in Arabidopsis. Within the Brassicaceae, several other motifs, but not the LFY and WUS binding sites previously identified, are highly conserved. The significance of these other conserved motifs has been confirmed by reporter gene analysis.
