Metabolomic and transcriptomic analyses provide new insights into the health benefits of hemp seeds (Cannabis sativa) in the Bama region of China

Hemp seeds Cannabis sativa L. have a variety of health benefits. They are widely consumed and used for the production of cooking oil. Hemp seeds have long been consumed by inhabitants of the Bama longevity villages in China, and they are thought to contribute to the high longevity of the local people. The gene editing and molecular breeding of hemp seeds have been greatly limited by our lack of understanding of the molecular regulation and accumulation of metabolites in hemp seeds at different stages of maturity. Here, we conducted metabolomic and transcriptomic analyses of hemp seeds from the Bama region at four maturity stages. The metabolomic analysis revealed that hemp seeds from the Bama region contain a greater number of flavonoid metabolites compared with seven other varieties from other regions in China. Some of the metabolites with the greatest health benefits include cannflavin, trigonelline, citric acid, vitexin, choline alfoscerate, and choline, and these might contribute to the high longevities of the Bama people. K means clustering analysis revealed two main groups of metabolites. The expression of genes and the accumulation of metabolites gradually decreased during the seed maturation process according to transcriptomic and metabolomic analyses, respectively. Genes and metabolites that regulate the maturity of hemp seeds were enriched in the following Kyoto Encyclopedia of Genes and Genomes pathways Flavonoid biosynthesis, MAPK signaling pathway plant, and Fatty acid biosynthesis. Weighted gene coexpression network analysis revealed two genes involved in regulating the accumulation of the main metabolites in hemp seeds; transcription factor association analysis revealed 221 transcription factor genes that are involved in regulating the accumulation of the main metabolites in hemp seeds. The results of our study provide valuable data on the metabolites and expression profiles of genes in hemp seeds during the seed maturation process.