There is more than one way to flower. In the thale cress, Arabidopsis thaliana, the well characterized FT gene encodes a pro-flowering protein that travels from leaf to shoot in response to changes in day length.
Now, Detlef Weigel and his colleagues at the Max Planck Institute for Developmental Biology in Tübingen, Germany, show that another pathway regulated by microRNAs — molecules that prevent translation of messenger RNAs into proteins — can stimulate flowering independently of daylight cues.
They find that levels of microRNA-156 decline as the plant ages, parallelling a rise in expression of the genes it seems to silence. The products of these genes, called SPLs, set off floral development.