Molecular integration of seasonal temperature signals in flowering time control

Abstract

Many plants sense and respond to temperature signals over long seasonal timescales to robustly time the transition to reproductive development — a process that will have to cope with the rapidly changing climate. Decades of genetic and molecular analyses have identified many genes influencing flowering in response to environmental signals. Among these, the regulation of one gene, FLOWERING LOCUS C (FLC), is central to requiring and responding to the prolonged cold of winter, aligning flowering with spring. Recent advances in our mechanistic understanding of FLC regulation suggest that, in contrast to a classic temperature signalling cascade, different aspects of natural fluctuating temperatures are monitored in parallel over various timescales and integrated through chromatin memory mechanisms, providing a robust way to accommodate climate variation. Dissecting the complexity and the source of adaptive variation in these flowering mechanisms helps in understanding the consequences of climate change with far-reaching implications for crop improvement. Plants must accurately time flowering by integrating seasonal temperature cues to ensure reproductive success. This Review describes how two mechanisms — rapid transcriptional responses and long-term epigenetic memory — work together in parallel to robustly control flowering time, and it highlights that variation in these processes provides important information for the future of crops under a changing climate.