promoter in rice is located in the phloem of the leaf along with the Hd3a mRNA. However, the Hd3a protein is found in neither of these places but instead accumulates in the SAM which shows that Hd3a protein is first translated in leaves and then transported to the SAM via the phloem where floral transition is initiated; the same results occurred when looked at Arabidopsis. These results conclude that FT/Hd3a is the florigen signal that induces floral transition in plants. Upon this conclusion, it became important to understand the process by which the FT protein causes floral transition once it reaches the SAM. The first clue came with looking at models from Arabidposis which suggested that a bZIP domain containing transcription factor, FD, is somehow interacting with FT to form a transcriptional complex that activates floral genes. Studies using rice found that there is an interaction between Hd3a and OsFD1, homologs of FT and FD respectively, that is mediated by the 14-3-3 protein GF14c. The 14-3-3 protein acts as intracellular florigen receptor that interacts directly with Hd3a and OsFD1 to form a tri-protein complex called the florigen activation complex (FAC) because it is essential for florigen function. The FAC works to activate genes needed to initiate flowering at the SAM; flowering genes in Arabidopsis include AP1, SOC1 and several SPL genes, which are targeted by a microRNA and in rice the flowering gene is OsMADS15 (a homolog of AP1). Antiflorigen Florigen is regulated by the action of an antiflorigen. Antiflorigens are hormones that are encoded by the same genes for florigen that work to counteract its function. The antiflorigen in Arabidopsis is TERMINAL FLOWER1 (TFL1) and in tomato it is SELF PRUNING (SP). Research history Florigen was first described by Soviet Armenian plant physiologist Mikhail Chailakhyan, who in 1937 demonstrated that floral induction can be transmitted through a graft from an induced plant to one that has not been induced to flower. Anton Lang showed that several long-day plants and biennials could be made to flower by treatment with gibberellin, when grown under a non-flower-inducing (or non-inducing) photoperiod. This led to the suggestion that florigen may be made up of two classes of flowering hormones: Gibberellins and Anthesins. It was later postulated that during non-inducing photoperiods, long-day plants produce anthesin, but no gibberellin while short-day plants produce gibberellin but no anthesin. However, these findings did not account for the fact