The Flowering Hormone Florigen Accelerates Secondary Cell Wall Biogenesis to Harmonize Vascular Maturation with Reproductive Development

The protein hormone florigenis a universal systemicinducer of flowering that also functions as a generic growth terminator across flowering plants. To understand the developmental rational for its pleiotropicfunctions and to uncover the deep cellular systems mobilized by florigenbeyond flowering we explored termination of radial expansion of stems. Employing the power of tomato genetics along with RNAseq and histological validations we show that endogenous, mobile, or induced florigenaccelerates secondary cell wallbiogenesis (SCWB), and hence vascular maturation, independently of flowering. This finding is supported by a systemic florigenantagonist from the non-flowering Ginkgo biloba, which arrests SCWB and by MADS and MIF genes downstream of florigenthat similarly suppress or enhance, respectively, vascular maturation independent of flowering. By accelerating SCWB, florigenreprograms the distribution of resources, signals and mechanical loadsrequired for the ensuing reproductive phase it had originally set into motion.