2026 年 76 巻 4 号 p. 331-340
The transition from mitotic proliferation to meiotic division is a defining developmental event in reproduction. In land plants, meiotic entry occurs within complex multicellular tissues and must be precisely coordinated with developmental cues. Recent studies have revealed that meiotic initiation is not a simple cell-cycle switch but is genetically and mechanistically separable from germ-founder cell specification, leading to the emerging concept that meiotic entry is governed by a hierarchical licensing system operating prior to irreversible commitment to meiosis. This review summarizes current knowledge of the developmental, metabolic, redox, and post-transcriptional mechanisms that establish meiotic competence in plants, and discuss how environmental and metabolic inputs, such as temperature and nitrogen availability, are linked to intracellular permissiveness through these mechanisms, ultimately converging on a meiotic commitment point that marks the transition to meiotic mode. Finally, it is proposed that meiotic entry in multicellular land plants represents a developmentally programmed engagement of intrinsic stress-response pathways evolutionarily originated in unicellular organisms. A deeper understanding of these mechanisms will provide a foundation for future studies improving reproductive stability and crop fertility under global climate change.
