THE FLOWERING-TIME GENE FT AND REGULATION OF FLOWERING IN ARABIDOPSIS

Transition from vegetative to reproductive development (flowering) is one of the most important decisions during the post-embryonic developm ent of flowering plants. More than twenty loci are known to regulate t his process in Arabidopsis. Some of these flowering-time genes may act at the shoot apical meristem to regulate its competence to respond to floral inductive signals and floral evocation. Genetic and phenotypic analyses of mutants suggest that the late-flowering gene FT may be a good candidate for such genes. To test this, we have cloned the FT gen e using a FT-deficiency line associated with a T-DNA insertion. Cloned genes and loss-of-function mutants in hand, it is now possible to ana lyse the role of FT and other genes in flowering at the biochemical an d cellular levels as well as at the genetic level. The deduced FT prot ein has homology with TFL1 and CEN proteins believed to be involved in regulation of inflorescence meristem identity. Phylogenetic analysis suggests that the FT group and the TFL1/CEN group of genes diverged be fore the diversification of major angiosperm clades. This raises the i nteresting question of the evolutionary relationship between the regul ation of vegetative/reproductive switching in the shoot apical meriste m and the regulation of inflorescence architecture in angiosperms.