FT-like genes in Cannabis and hops: sex specific expression and copy-number variation may explain flowering time variation

Cannabis sativa is a fascinating, yet under-researched, species. To facilitate the global expansion of C. sativa cultivation a greater understanding of flowering time control is crucial. The PEBP gene family consists of universal promoters and repressors of flowering, with homologs of FLOWERING LOCUS T (FT) being highly conserved key regulators of flowering. FT encodes florigen, and balancing the florigen and anti-florigen signals is key for fine-tuning a crop’s flowering to local climatic conditions. Here, we provide an in-depth characterisation of the PEBP gene family in C. sativa and the closely related species H. lupulus. Phylogenetic analysis reveals expansion of FT and TFL1/CEN clades in the Cannabaceae. The retention of the duplicated PEBP genes may be of functional significance, with divergent sequences and expression patterns hinting at signatures of sub-functionalisation. We speculate that duplicated PEBP genes have been crucial to the evolution of photoperiod insensitivity and sexually dimorphic flowering in C. sativa and harnessing the available genetic variation for these traits will be key for establishing C. sativa as a crop for the future.