Genome-wide identification and characterization of CONSTANS-like transcription factors reveal that three CsCOLs regulate the cannabinoid biosynthesis in Cannabis

Abstract

Cannabis (Cannabis sativa L.) has been cultivated as a versatile industrial crop for millennia, serving for food, fiber, and medicine. Cannabinoids are characteristic medicinal active compounds in cannabis, mainly being rich in female inflorescences. CONSTANS-like (COL) transcription factors are primarily involved in the photoperiod process of flowering plants. However, knowledge about their regulatory mechanism for secondary metabolites is limited. Eleven CsCOLs were identified from the cannabis genome based on the phylogenetic relationship and conserved domains in this study. The number of CsCOLs in cannabis showed apparent contraction and their functional divergence. CsCOL1, CsCOL5, and CsCOL7 exhibited high expression in flowers and bracts and their overexpression elevated the content of CBDA and CBGA by promoting the expression of related structural genes involved in cannabinoid biosynthesis. In addition, CsCOL7 was bound to the promoters of four structural genes, including CsAAE, CsOLS, CsPT4, and CsCBDAS, to regulate their gene expression in the manner of repressing the upstream and activating the downstream genes. CsCOL1 positively regulated the expression of CsPT4 and CsCBDAS. In addition, CsCOL5 positively regulated the expression of CsOLS and CsPT4 via binding of their promoters. Here, we explored the potential transcription regulation mechanism of CsCOLs in cannabinoid biosynthesis in C. sativa for the first time, even though a more profound investigation should be conducted in cannabis plants in the future. The findings expanded the knowledge of COLs in regulating secondary metabolites and provided insights into CsCOLs in cannabinoid biosynthesis.