A Time and a Place for a Flower

Abstract

Early plant responses to spring environmental signals, such as day length or vernalization, occur in the leaves, but the flowers form at a meristem that shifts from vegetative to floral growth. The mysterious mobile mediator between these two sites has been called "florigen." Wigge et al. and Abe et al. investigated the integration of floral initiation signals in Arabidopsis (see the Perspective by Blázquez). Flowering locus T ( FT ) is expressed in leaves in response to environmental changes conducive to flowering. Meanwhile, the meristem is primed to be ready for floral production by expression of a transcription factor, FD. Together, FT and FD activate floral identity genes. Whether FT actually is the mobile mediator remains unclear, but these two genes together do integrate the "when" and the "where" of the flowering response. P. A. Wigge, M. C. Kim, K. E. Jaeger, W. Busch, M. Schmid, J. U. Lohmann, D. Weigel, Integration of spatial and temporal information during floral induction in Arabidopsis . Science 309 , 1056-1059 (2005). [Abstract] [Full Text] S. Abe, Y. Kobayashi, S. Yamamoto, Y. Daimon, A. Yamaguchi, Y. Ikeda, H. Ichinoki, M. Notaguchi, K. Goto, T. Araki, FD, a bZIP protein mediating signals from the floral pathway integrator FT at the shoot apex. Science 309 , 1052-1056 (2005). [Abstract] [Full Text] M. A. Blázquez, The right time and place for making flowers. Science 309 , 1024-1025 (2005). [Summary] [Full Text]