One of the major molecules studied in the Blackman lab is FLOWERING LOCUS T (FT), a pretty amazing protein. Its expression is induced in the leaf only under the certain day lengths that tell the plant that the best time of the season for flowering has arrived. FT protein must then move out of the leaf through the plant’s vasculature to the shoot apex. There, it will turn on genes that essentially tell the apical cells to stop developing into leaves and shoots and start developing into floral structures. Even though we’ve known FT does this for over a decade, the means by which it moves from the leaf to the apex have remained virtually unknown. A recent paper in Nature Plants solves part of this mobility mystery by showing that a molecule called SODIUM POTASSIUM ROOT DEFECTIVE 1 (NaKR1) is required for FT to move up the phloem of the plant vasculature to the apex. This comes in addition to another protein, FTIP1, that gets it out of the leaf and into the phloem, but the molecule that gets FT from where NaKR1 leaves it in the phloem just below the apex and then into the apical cells still remains to be discovered. Check out the paper to see how they showed NaKR1 does this important and intricate job of transporting its key cargo for transmitting the floral induction signal.
--Ben Blackman