Transcriptomic insights into unisexual flower development in Cannabis sativa: conserved gene networks and perianth identity in male flowers

Background: Cannabis sativa , a dioecious species characterized by striking sexual dimorphism and exceptional sexual plasticity, presents a powerful model for exploring floral development and the evolution of dioecy. The unique male and female flowers each feature a single perianth whorl that differs significantly in structure and developmental trajectory, raising key questions about organ identity and developmental regulation that remain largely unresolved. Results: We demonstrate that male flowers undergo more extensive transcriptional reprogramming than female flowers, suggesting a more complex developmental trajectory. Analysis of MADS-box gene expression reveals that, despite sexual dimorphism and structural reduction, both sexes conform to the canonical ABCDE model of floral organ identity, indicating unisexual flower development relies on conserved regulatory networks. Critically, by integrating molecular and morphological evidence, we demonstrate that the male perianth exhibits petal-like identity, addressing a longstanding uncertainty in Cannabis organ morphology. Conclusions: This study provides molecular and morphological evidence strongly suggesting that the male Cannabis perianth possesses petaloid characteristics, offering a new perspective on a key floral trait. Our findings demonstrate that despite structural reduction and unisexual development, Cannabis employs conserved ABCDE regulatory networks, suggesting that B-class genes link petal and stamen development. This work establishes a developmental-genetic framework for understanding dioecy evolution and highlights how wind pollination may drive perianth reduction while maintaining underlying genetic programs.