A Pair of Related Genes with Antagonistic Roles in Mediating Flowering Signals

Flowering in Arabidopsis is promoted via several interacting pathways. A pho-toperiod-dependent pathway relays signals from photoreceptors to a tran-scription factor gene, CONSTANS (CO), which activates downstream meristem identity genes such as LEAFY (LFY). F T, together with LFY, promotes ßowering and is positively regulated by CO. Loss of F T causes delay in ßowering, whereas overexpression of F T results in precocious ßowering independent of CO or photoperiod. F T acts in part downstream of CO and mediates signals for ßowering in an antagonistic manner with its homologous gene, TERMINAL FLOWER1 (TFL1). In higher plants, flowering—the transition from vegetative to reproductive growth phase—is controlled via several interacting pathways influenced by both endogenous fac-tors and environmental conditions. In Arabi-dopsis, a photoperiod-dependent pathwa