We have created transgenic Arabidopsis plants in which a gene encoding the cell-autonomous diphtheria toxin A chain (DT-A) was expressed under the control of the LEAFY (LFY) promoter. This promoter is active both in emerging leaf primordia and young flowers, with the highest activity in flowers. The majority of LFY::DT-A plants had normal vegetative development but lacked flowers, demonstrating that relatively widespread activity of a promoter does not exclude its possible use for ablating selected tissues, as long as differences in activity levels between different tissues are significant. We also found that flowers were replaced by empty bracts in LFY::DT-A plants, suggesting that flower-derived signals normally suppress bract development in Arabidopsis.