Genome-Wide Characterization of PEBP, FD, and GRF Families in Amomum villosum Lour. and Their Potential Roles in Flowering

A detailed understanding of the molecular mechanisms governing the flowering time of Amomum villosum Lour., a medicinal plant within the Zingiberaceae family, is currently lacking. In modern plants, the florigen activation complex (FAC), which includes PEBP, FD/bZIP, and GRF proteins, is known to regulate flowering. In this study, we identified 13 PEBP, 5 FD, and 19 GRF genes within the A. villosum genome and conducted phylogenetic, structural and promoter analysis. Notably, cross-species protein–protein interaction predictions and yeast two-hybrid assays uncovered an unexpected interaction pattern: an AREB3-like FD protein (AvFD5) and a GRF protein (AvGRF13) directly interact with specific PEBP members, whereas canonical FD-like proteins (AvFD1 and AvFD4) did not, which contrasts with the classical rice FAC model (Hd3a-14-3-3-OsFD1). These results imply that FAC assembly in A. villosum may involve alternative components or regulatory mechanisms, potentially indicating lineage-specific divergence within monocots. This research represents the first systematic characterization of FAC core gene families in A. villosum and Zingiberaceae, laying the groundwork for understanding flowering time regulation and facilitating future molecular breeding efforts in this economically significant plant.