A Distal CCAAT/NUCLEAR FACTOR Y Complex Promotes Chromatin Looping at the FLOWERING LOCUS T Promoter and Regulates the Timing of Flowering in Arabidopsis

For many plant species, reproductive success relies on the proper timing offlowering, and photoperiod provides a key environmental input. Photoperiod-dependentflowering depends on timely expression of FLOWERING LOCUS T(FT); however, the coordination of variouscis-regulatory elements in the FT promoter is notwell understood. Here, we provide evidence that long-distance chromatin loops bringdistal enhancer elements into close association with the proximal promoter elementsbound by CONSTANS (CO). Additionally, we show that NUCLEAR FACTOR Y (NF-Y) binds aCCAAT box in the distal enhancer element and thatCCAAT disruption dramatically reduces FTpromoter activity. Thus, we propose the recruitment model of photoperiod-dependentflowering where NF-Y complexes, bound at the FT distal enhancerelement, help recruit CO to proximal cis-regulatory elements andinitiate the transition to reproductive growth.