Florigen family chromatin recruitment, competition and target genes

<jats:title>Abstract</jats:title><jats:p>Plants monitor seasonal cues, such as day-length, to optimize life history traits including onset of reproduction and inflorescence architecture<jats:sup>1–3</jats:sup>. Florigen family transcriptional co-regulators TERMINAL FLOWER 1 (TFL1) and FLOWERING LOCUS T (FT) antagonistically regulate these vital processes<jats:sup>4–6</jats:sup>yet how TFL1 and FT execute their roles and what the mechanism is for their antagonism remains poorly understood. We show genome-wide, that TFL1 is recruited to the chromatin by the bZIP transcription factor FLOWERING LOCUS D (FD) in<jats:italic>Arabidopsis</jats:italic>. We find that seasonal cue-mediated upregulation of FT competes TFL1 from chromatin-bound FD at key target loci. We identify the master regulator of floral fate,<jats:italic>LEAFY</jats:italic>(<jats:italic>LFY</jats:italic>) as a target under dual opposite regulation by TFL1 and FT. Exonic bZIP motifs in<jats:italic>LFY</jats:italic>are critical for repression by TFL1, upregulation by FT and adoption of floral fate. Transcriptomic identification of target genes directly repressed by the TFL1-FD complex not only identifies key regulators of onset of reproduction and floral fate, but reveals that TFL1-FD repress sugar and hormone signalling pathways and chromatin regulators. Our data provide mechanistic insight into how florigen family member sculpt inflorescence architecture, a trait important for reproductive success and yield.</jats:p>