FE, a phloem-specific Myb protein, regulates the long-distance transport of the mobile floral signal FT

FLOWERING LOCUS T (FT) represents the essential component of florigen that promotes flowering in response to seasonal changes in day-length. In Arabidopsis, the FT protein is produced in the leaves and transported through the phloem to the shoot apex. However, the molecular basis underlying this FT movement remains elusive. Here, we identify a phloem-specific protein, FE, as a crucial regulator of the long-distance transport of FT. The fe-1 mutation abolishes the transport of FT to the shoot apex. Our data indicate that FE plays a pivotal role in the export of FT into the phloem via up-regulation of several downstream targets including a plasmodesmata-localized synaptotagmin-like protein and a metallochaperone protein.