Integrated Transcriptome and Metabolome Analyses Reveal the Roles of MADS-Box Genes in Regulating Flower Development...

The MADS-box transcription factors play essential roles in various processes of plant growth and development. Here, we identified 107 MADS-box genes in Osmanthus fragrans Lour. genome (OfMADS), encoding proteins ranging from 61 to 608 amino acids. Phylogenetic analysis classified these genes into five subfamilies: MIKC*, MIKCC, Mα, Mβ, and Mγ, with conserved motif architectures within subfamilies. Tandem and whole-genome duplications were identified as key drivers of OfMADS expansion. Cis-regulatory element analysis revealed enrichment for hormone response and developmental regulatory motifs, implicating roles in growth and flowering processes. Transcriptome dynamics across six floral developmental stages (bolting to petal shedding) uncovered 78 differentially expressed OfMADS genes, including 16 exhibiting flower-specific expressions. Integrated metabolome profiling demonstrated robust correlations between critical OfMADS regulators and scent metabolites. This nexus suggests a potential role of these OfMADS in regulating specialized metabolite biosynthesis pathways. Our multi-omics study provides insights into the regulatory hierarchy of OfMADS in coordinating floral morphogenesis and the accumulation of economically significant metabolites in O. fragrans. These findings establish a foundation for subsequent functional validation and molecular breeding of horticultural traits.