Science 339, 704–707 (2013)

Credit: Vanessa Wahl

To guarantee reproductive success, plants regulate flowering to ensure that it occurs under optimal environmental and metabolic conditions. Leaves sense a lengthening photoperiod, which triggers production of FLOWERING LOCUS T (FT), a mobile florigen that induces flower development in the shoot apical meristem (SAM). Plants also sense whether they have sufficient energy resources for flowering, and mutations in genes involved in carbohydrate metabolism delay flowering. Wahl et al. now show that trehalose-6-phosphate (T6P) regulates several flowering pathways in Arabidopsis thaliana. Knockdown of TREHALOSE-6-PHOSPHATE SYNTHASE 1 (TPS1), the enzyme that synthesizes T6P, reduces T6P cellular concentrations and delays flowering. In wild-type plants, T6P concentrations correlate with carbohydrate abundance and undergo cycling with a diurnal period. However, in TPS1 mutants, the expression of FT is blocked, suggesting that TPS1 acts upstream of FT in regulating the photoperiod pathway in leaves. T6P also controls floral induction directly in the SAM. Microarray analysis of TPS1 mutants revealed that T6P partially regulates SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) proteins, known to be involved in age-dependent induction of flowering in the SAM. Though further research will be required to establish the molecular mechanism of T6P action in plants, the current study highlights an additional role of trehalose derivatives in regulating biological systems.