Rewiring of LEUNIG_HOMOLOG interaction networks marks regulatory shifts from meristem to organ growth in Arabidopsis flowers.

LEUNIG (LUG) and LEUNIG_HOMOLOG (LUH) are Groucho/Tup1-type transcriptional co-regulators in Arabidopsis thaliana that act redundantly across multiple developmental and environmental response pathways. Their specific contributions to flower development, however, have remained unclear due to embryonic lethality of double mutants. Here, we show that LUH associates with distinct sets of transcription factors and chromatin-associated proteins in a developmentally dynamic manner. Chromatin occupancy and protein interactions shift from a meristem-focused network during early floral patterning to an organogenesis-oriented state as primordia initiate and expand. Reduced promoter-proximal LUH binding coincides with this proliferative phase, suggesting a transient reconfiguration of LUH activity. By later stages, LUH activity is amplified alongside organ differentiation programs. Together with LUG, LUH modulates gene expression programs that are essential for establishing floral organ patterning. These findings reveal how dynamic co-regulator assemblies contribute to the temporal coordination of growth and spatial pattern formation in Arabidopsis flowers.