{
  "id": 3275759,
  "title": "Spatiotemporal Profiling of the Marchantia Sporophyte Reveals Ancestral Meristem Module and Dynamic Epigenetic Reprogramming during Early Embryogenesis",
  "url": "https://urgent.news/2026/08/25/spatiotemporal-profiling-of-the-marchantia-sporophyte-reveals",
  "topic": "science",
  "section": "Science",
  "published": "2026-08-25T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.08.24.746769v1?rss=1"
  },
  "original_language": "en",
  "account": "The emergence of a multicellular embryo marks a significant innovation in the evolution of land plants, and serves as the starting point for the diversification of complex life cycles with alternating haploid and diploid generations. In the liverwort Marchantia polymorpha, the sporophyte is simple and dependent on the gametophyte for nutrition, making it an ideal model for studying the ancestral programs of plant embryogenesis. A comprehensive spatiotemporal transcriptomic atlas of Marchantia sporophyte development was created, utilizing laser-assisted microdissection followed by RNA sequencing, which revealed seven distinct tissue types at three developmental stages. The young embryo exhibited unique gene expression patterns associated with early embryogenesis, sporogenous specification, and late tissue differentiation. The transcriptome of the embryonic stage was marked by the coordinated activation of auxin-response networks and cell-cycle regulators. The apical domain retained a conserved sporogenous expression profile, primarily defined by Class III HD-ZIP and HMG-box transcription factors. In contrast, hypobasal-derived tissues displayed pronounced functional specialization, with the foot enriched for metabolic and membrane transport functions, and the seta showing gene expression patterns indicative of cell proliferation. Phylotranscriptomic analysis unveiled a developmental hourglass pattern, characterized by a conserved mid-embryonic transcriptomic bottleneck dominated by evolutionarily ancient genes. This bottleneck indicates that the embryonic constraint predates the development of morphological complexity in land plants. Furthermore, through allele-specific expression analysis, it was observed that genome-wide paternal silencing was progressively established during embryogenesis, occurring independently from early Polycomb-mediated H3K27me3 marks. These findings shed light on the ancestral regulatory programs that underlie sporophyte development and provide a valuable resource for unraveling the evolutionary origins of plant embryogenesis.",
  "summary": "The emergence of a multicellular embryo was a key innovation in land plant evolution and stands at the beginning of the diversification of complex life cycles with an alternation of haploid gametophytic and diploid sporophytic generations that are multicellular. In the liverwort Marchantia polymorpha, the sporophyte remains simple and nutritionally dependent on the gametophyte, providing an…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}