Effects of FT on FD during the transition to flowering at the SAM in Arabidopsis thaliana

The transition to flowering is a crucial step in the plant life cycle that is controlled by multiple endogenous and environmental cues, including hormones, sugars, temperature, and photoperiod. Permissive photoperiod induces FLOWERING LOCUS T (FT) in the phloem companion cells of leaves. The FT protein then acts as a florigen that is transported to the shoot apical meristem (SAM) where it physically interacts with the bZIP transcription factor FD and 14-3-3 proteins. However, despite the importance of FD for promoting flowering, its direct transcriptional targets are largely unknown. Here we applied ChIP-seq and RNA-seq to identify targets of FD at the genome scale and assess the contribution of FT to binding DNA. We further investigated the ability of FD to form protein complexes with FT and TFL1 through the interaction with 14-3-3 proteins. Importantly, we observe direct binding of FD to targets involved in the jasmonate signaling pathway, which so far had not been directly linked to the regulation of flowering time. Our study confirms FD as central regulator of the floral transition at the shoot meristem and provides evidence for crosstalk between the regulation of flowering and jasmonate signaling.