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Floral ontogeny in soybean (Glycine max) is governed by multilayered regulatory hierarchies that integrate phytohormonal cues with precisely choreographed gene-expression programs. Yet, the transcriptomic architecture underpinning this continuum remains only partially resolved. Here, we generated a strand-specific, high-depth temporal transcriptome atlas of soybean inflorescences spanning four morphologically defined stadiums (Stadium 0–Stadium 3). We detected transcriptional activity for 60,889 loci; pairwise stadium contrasts revealed 4000–7000 differentially expressed genes, with the most extensive reprogramming coinciding with the onset of anthesis (Stadium 2). Unsupervised clustering delineated ~600 genes peaking at the pre-anthesis phase (Stadium 1), a cohort enriched for transcriptional regulators and floral organ-identity determinants. Stadium-resolved gene-set enrichment and KEGG mapping uncovered dynamic modulation of canonical hormone-signaling pathways—including auxin, cytokinin, gibberellin, abscisic acid, ethylene, jasmonate, and salicylate circuits—reflecting shifting developmental priorities. Forty-five MADS-box transcription factor genes were expressed; notably, JOINTLESS was strongly induced at anthesis, while the root-predominant factor GmNMH7 exhibited unexpected floral expression, implicating a hitherto unappreciated role in reproductive development. Quantitative RT-PCR of representative loci corroborated RNA-seq measurements. This high-resolution atlas refines our understanding of the hormonal and genetic circuitry of soybean floral morphogenesis, furnishing molecular targets for engineering flowering time and inflorescence architecture under fluctuating environmental conditions.
Virág et al. (Fri,) studied this question.