Genome-wide characterization of MADS-box genes reveals CsaSOC1 as a key regulator of flowering in Cannabis sativa L

Abstract

This study identified 57 CsaMADS genes in Cannabis sativa L., characterized the expression and homology of key candidates CsaSOC1 and CsaFUL, and confirmed their protein interaction, thereby providing a molecular basis for investigating flowering regulation. MADS-box transcription factors are central regulators of plant growth and development, particularly in floral morphogenesis and the control of flowering time. In this study, we identified 57 MADS-box genes in hemp (Cannabis sativa L.) and classified them into Type I (22 genes) or Type II (35 genes) groups, which were further categorized into 15 distinct subfamilies. Genes within the same subfamily exhibited similar exon-intron structures and highly conserved protein motifs. Evolutionary analysis of MADS-box family members revealed that seven tandem and seven segmental duplication events had contributed to the expansion of the MADS-box gene family in hemp. Promoter analysis uncovered numerous cis-acting elements associated with light responsiveness, phytohormone signaling (including auxin and gibberellin), and environmental stress responses. Transcriptomic profiling showed that most CsaMADS-box genes are highly expressed in floral tissues, supporting their roles in reproductive development. Notably, a SOC1-like gene, CsaSOC1, was identified as a potential flowering integrator, and its physical interaction with CsaFUL was confirmed by yeast two-hybrid and luciferase complementation assays. Together, these results provide a comprehensive genomic overview of the MADS-box gene family in hemp and establish a valuable foundation for future functional studies of flowering regulation.

Keywords: Cannabis sativa L. (hemp); Flowering regulation; Expression profiling; Gene duplication; Genome-wide analysis; MADS-box transcription factors; Protein–protein interaction.