A pistillate-biased epidermal regulatory program underlies glandular trichome development in Cannabis sativa

Abstract/SummaryGlandular trichomes are specialized epidermal structures on Cannabis sativa L. inflorescences that synthesize and store cannabinoids and terpenoids, making them central to the species economic and medicinal value. Although trichome development is a multistage genetic process, its regulatory basis in C. sativa remains poorly understood, particularly with respect to sexual dimorphism and sex plasticity. Here, we combined orthology-based gene discovery with transcriptomic profiling to investigate trichome development across four floral phenotypes: female flowers (FF), male flowers (MF), induced male flowers on XX plants (IMF), and induced female flowers on XY plants (IFF). Using trichome development-related genes from Arabidopsis thaliana, a model for unicellular non-glandular trichome development, and Solanum lycopersicum, a model for multicellular glandular trichomes, we identified and mapped 53 candidate C. sativa trichome development regulator genes (CsTDRGs). The CsTDRG set did not support a simple Arabidopsis- or tomato-like model, but instead included Arabidopsis-like epidermal fate components, including MBW-related regulators and GL2, alongside tomato-like multicellular trichome regulators, including MIXTA-like, HD-ZIP IV, WOX, MTR, GRAS, and hormone-associated candidates. RNA-seq analysis showed that CsTDRG expression was more strongly associated with floral phenotype than chromosomal sex. Genes with preferential expression in pistillate tissues were CsTT8, CsMYC1/GL3, CsGL2, CsYABBY4 and CsMIXTA-like1/MYB106, whereas CsMTR1, CsGRAS9, and CsCKX3 were upregulated in male (MF and IMF) flower. These findings suggest that sexually dimorphic trichome development in C. sativa reflects differential regulation of a shared developmental toolkit that combines conserved epidermal fate components with multicellular and glandular trichome regulatory modules.