Metabolomic and Transcriptomic Analyses Provide New Insights into Health-Promoting Metabolites from Cannabis Seeds Growing in the Bama Region of China

Abstract

Hemp seeds are consumed in “Bama longevity villages” in China and are believed to contribute to the locals’ longevity. However, the molecular breeding of hemp seeds is limited due to our lack of understanding of molecular regulation and metabolite accumulation at different maturity stages. Here, we conducted metabolomic and transcriptomic analyses of hemp seeds from the Bama region at four maturity stages (S1 to S4). In total, 1231 metabolites of 11 classes were detected in hemp seeds from S1–S4, including 233 flavonoids, 214 phenolic acids, 159 lipids, 118 amino acids and derivatives, 100 alkaloids, 100 organic acids, 71 nucleotides and derivatives, 43 lignans and coumarins, 14 terpenoids, 13 tannins, and 166 others. The metabolomic analysis of hemp seeds (from the Bama region) revealed a higher number of flavonoid metabolites compared with seven other varieties from other regions in China. Hemp seeds are rich in metabolites like cannflavin, trigonelline, citric acid, vitexin, choline alfoscerate, and choline, which may potentially contribute to the longevity of the Bama people. Through transcriptomic and metabolomic analyses, a gradual decrease in the overall expression pattern of genes and metabolite accumulation was observed during seed maturation. Weighted gene co-expression network analysis revealed that two genes (ncbi_115696993 and ncbi_115706674) are involved in regulating main metabolites, while transcription factor association analysis revealed that three transcription factor genes (MYB, NAC, and GRAS) are also involved in regulating the metabolites. The expression pattern of these five candidate genes was further verified by qPCR. Our study provides valuable insights into the metabolic substances during seed maturation and identifies candidate genes that could be utilized for future genetic engineering to enhance the endogenous biosynthesis of health-promoting metabolites in hemp seeds, potentially leading to improved nutritional and medicinal properties.