Integrative control of plant sex determination: Genes, hormones, and environment.

Plant sex determination involves the integration of genetic networks, hormonal signaling and environmental cues. This review synthesizes current understanding, highlighting two conserved pathways for unisexual flower formation: Type I (post-initiation organ abortion) and Type II (primordial suppression). Floral organ identity is genetically orchestrated by the ABCDE model and specific sex-determining genes. The core hormonal mechanism centers on antagonistic interactions between gibberellin (promoting male) and ethylene (promoting female), mediated by regulators like DELLA and EIN3/EIN2. These hormones integrate endogenous balances and environmental signals to control downstream transcription factors and sex gene expression. Environmental factors such as light, temperature and nutrients can significantly modulate sex expression, often overriding genetic programs via epigenetic mechanisms (e.g.,photoperiod-induced DNA methylation) and metabolic shifts, enabling phenotypic plasticity for reproductive fitness. Despite advances, gaps remain in transcriptional regulation, network integration, and species-specific adaptations. Future work should integrate gene editing (e.g., CRISPR-Cas9) and systems biology to deepen understanding of sexual plasticity by elucidating the transcriptional regulation of sex-determining genes and their interactions with hermaphroditic floral programs. This framework emphasizes unifying genetic hierarchies, hormonal dynamics and environmental plasticity for a comprehensive model.