Florigen sequestration keeps plants from flowering in the cold

Temperature-dependent sequestration of florigen into the lipid membranes of plant vascular cells keeps plants from flowering when it’s too cold, according to a new study. Understanding how plants respond to temperature and how ambient temperature drives the reproductive cycle of flowering plants may provide important insight into the effects of climate change on agricultural production. Plants often improve their ability to survive and reproduce by monitoring key environmental cues, such as day length and ambient temperature – using the information to modulate stages in growth and development, including when to grow flowers and initiate their reproductive program. Florigen – a plant hormone that initiates flower growth – is produced in leaf cells when days become longer. It moves through the plant, where it induces the development of flowers at the shoot apical meristem. One of the widely conserved characteristics of florigen is its ability to bind to lipids. The purpose of this function, however, has remained largely unknown. In this study, Hendry Susila and colleagues evaluated the activity of the florigen FLOWERING LOCUS T (FT) and how intracellular lipid membranes regulate the transport of this protein to modulate the timing of flowering. Using the flowering plant Arabidopsis thaliana as a model, Susila et al. show that FT binds with the phosopholipid phosphatidylglycerol, which sequesters the florigen in membrane compartments within phloem cells at low temperature, delaying flowering during cold conditions. This lipid binding is less favored at higher temperatures, allowing FT to be released into the plant’s shoots to drive flowering. Yvon Jaillais and François Parcy discuss the study and its findings in a related Perspective.