Fig. 1

Model of Hd3a/FT action in rice and Arabidopsis. Hd3a/FT protein is synthesized in the vascular tissue of the leaf and transported through phloem tissue. Hd3a/FT protein is unloaded from the end of the vascular tissue and enters into the SAM through the cells just below the SAM. Several lines of evidence suggest that Hd3a/FT protein interacts with the bZIP transcription factor FD, which directly binds promoter region of floral meristem identity gene AP1. Hd3a/FT is a strong candidate for florigen.