Abstract
Hemp possesses significant healthcare value due to its rich composition of unsaturated fatty acids and a distinctive golden ratio of linoleic acid to α-linolenic acid. As a promising special-oil crop, it holds substantial potential for development and utilization. However, the regulatory mechanisms underlying its lipid metabolic pathways remain poorly understood. In this study, the independently bred hemp seed variety Longdama No. 9 was used to construct a regulatory network of the fatty-acid and lipid metabolisms through integrative transcriptomic and lipidomic analysis. Transcriptomic profiling revealed differentially expressed genes (DEGs) involved in lipid biosynthesis across various tissues. In leaves, DEGs associated with glycerolipid synthesis were generally upregulated compared to in roots and seeds. In seeds, DEGs involved in fatty-acid synthesis and triacylglycerol (TAG) assembly were predominantly upregulated. Meanwhile, root tissues showed a higher abundance of upregulated DEGs related to phospholipid biosynthesis. Lipidomic analysis further highlighted tissue-specific lipid distributions. The galactolipid monogalactosyldiacylglycerol (MGDG) was most abundant in the leaves. While phosphatidylglycerol (PG) had the highest molar percentage in the seeds, most other major phospholipids were predominantly found in the roots. The prevalence of the C36:6 molecular species in the MGDG and digalactosyldiacylglycerol (DGDG) indicates that hemp is a typical 18:3 plant. The combined transcriptomic and lipidomic analysis revealed that tissue-specific transcriptional regulation contributes to the unique lipid profile of hemp. These findings provide valuable insights into the regulation of lipid metabolism in hemp and identify key genes involved in oil biosynthesis, which can lay a theoretical foundation for the development and utilization of hemp as a special-oil crop.