Gibberellin pathway remodeling accompanies ethylene-driven sex reversal in Cannabis sativa.

INTRODUCTION: Sex expression in Cannabis sativa is determined by XX/XY sex chromosomes but remains plastic, with ethylene inhibition inducing male flowers on XX plants and ethylene release inducing female flowers on XY plants. Although ethylene is a central regulator of this process, the contribution of the gibberellin (GA) pathway to cannabis sex reversal remains poorly defined. METHODS: We reconstructed the GA biosynthesis, regulation, and signaling pathway in C. sativa using orthology-based searches, and profiled GA-related gene expression during chemically induced sex reversal through transcriptomic analyses spanning the vegetative baseline, early post-treatment leaves, and developing flowers. RESULTS: Orthology-based searches identified 50 putative C. sativa GA-related genes distributed across the genome, with 11 on the X chromosome, including six in the non-recombining region. Expression profiles were broadly similar between XX and XY plants at day 0, weakly perturbed at day 1, and strongly structured by floral phenotype at day 14. Early responses were limited to downregulation of CsGA3ox1 in ethephon-treated XY plants and CsGASA1 in STS-treated XX plants. By day 14, sex reversal was associated with differential expression of CsGA1, multiple GA20ox orthologs, CsGID1B, CsSLY2, and several GASA genes, indicating broad remodeling of GA-related transcription. DISCUSSION: These results show that ethylene-pathway manipulation is associated with time- and phenotype-dependent changes in GA-related gene expression, pointing to a contribution of the GA pathway to cannabis sex reversal.