Timing is everything in plant development. The central role of floral repressors

Progress in understanding the molecular basis of flowering time control has revealed that floral repressors play a central role in modulating the floral transition and are essential to prevent the precocious onset of flowering. A number of cellular processes including chromatin remodeling, selective protein degradation, and transcriptional regulation mediated by transcription factors are involved in repressing the initiation of flowering. Floral repressors interact at different levels with floral inductive pathways and prevent the premature onset of flowering that could impact negatively on the reproductive success of plants. Despite recent advances, further studies will be needed to understand how the interactions between floral repressors and the regulatory networks involved in the control of flowering time have evolved in different species. Recent data suggest that a diversity of regulatory proteins act as central floral repressors in different plants, and even in those species where regulatory modules are conserved new elements that modulate the function of these pathways have been recruited to mediate specific adaptive responses. The development of genomic tools and predictive models that can integrate large datasets related to the flowering behavior of plant species will facilitate the characterization of the repressor mechanisms underlying flowering responses, a trait with implications in the yield of crop species. In a scenario of global climate change, an in depth understanding of these gene circuits will be essential for the development of crop varieties with improved yield.

• Floral repressors are essential for precise control of flowering time.
• A regulatory module for the photoperiodic control of flowering is widely conserved, although new elements have been recruited to this pathway in different plant species.
• Plants have developed different strategies to establish a block to flowering that is suppressed during the vernalization response.
• Chromatin remodeling processes play a central role in the repression of key flowering time genes.